tag:blogger.com,1999:blog-29521705600312585992024-03-17T08:16:13.576+00:00Exo CruiserExocruiser, mostly aerospace related material.Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.comBlogger193125tag:blogger.com,1999:blog-2952170560031258599.post-60996800405147471142019-02-27T14:56:00.004+00:002019-02-27T15:50:02.562+00:00NMEA 2000 Explained<span style="color: #274e13;"><i>["What this doesn't address is the fact that just becasue the NMEA 2000 network
is powered you still will have to run the power cable for chartplotter
or a GPS combo unit as the NMEA backbone, as this video states, doesn't
have much power.
When I installed my NMEA 2000 network I was under the assumption that the
NMEA network would power all my stuff and there would be no need for the
original power supply to be ran to back of chartpotter and other bigger
units.
great video but addressing what was said above would be great." -- "You can only give power to the little displays with the nmea alone." - /YouTube comments/] </i></span><br />
<br />
"NMEA 2000 (IEC 61162-3) is a low cost, moderate capacity (250 K- bits/second), bi-directional multi-transmitter/multi-receiver instrument network to interconnect marine electronic devices. /1/<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5mjeMOWysmjjTLRf1f6uZOvxptaFkh_VdT-JXBs6GsNNtt9wbj7WvBjQqkxvgMYXaKKC-Ua-n3JNiHavkfVOkY-cV6HnFSbiL5MbHJjLMKvfuwr2Kn517tXNc2HbQphKYDtTNrOlUIXzM/s1600/n2k+on+boat.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="391" data-original-width="800" height="195" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5mjeMOWysmjjTLRf1f6uZOvxptaFkh_VdT-JXBs6GsNNtt9wbj7WvBjQqkxvgMYXaKKC-Ua-n3JNiHavkfVOkY-cV6HnFSbiL5MbHJjLMKvfuwr2Kn517tXNc2HbQphKYDtTNrOlUIXzM/s400/n2k+on+boat.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. NMEA 2000 network.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The NMEA 2000 standard contains the requirements for the minimum implementation of a serial-data communications network to interconnect marine electronic equipment onboard vessels. Equipment designed to this standard will have the ability to share data, including commands and status, with other compatible equipment over a single signaling channel.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgftNYCc6PQGGuWPw1AXTt2bx1qFsjLSduyIYxbuf48t6DgMN_zNk711Q1pGHfHDZ8NYl1oMCk-Sr-GoyKBn0Nh5-O6NV3QB5RzRtzesv_HDFgD31Fi_RY131HVzI6gOXkHFWIZQocYKW1E/s1600/amphenolnmea2000Applications.png.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="658" data-original-width="970" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgftNYCc6PQGGuWPw1AXTt2bx1qFsjLSduyIYxbuf48t6DgMN_zNk711Q1pGHfHDZ8NYl1oMCk-Sr-GoyKBn0Nh5-O6NV3QB5RzRtzesv_HDFgD31Fi_RY131HVzI6gOXkHFWIZQocYKW1E/s400/amphenolnmea2000Applications.png.jpeg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 2. Networking a ship.</span></i></span></td></tr>
</tbody></table>
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Increasingly, modern marine electronic equipment requires data from multiple sources to enable the host of features and function that can be available to the mariner. Without a network standard to provide this data integration, equipment designers must provide multiple data inputs, which involve expense and additional wiring, or use devices that merge data onto a single channel. Individual systems on a vessel, such as engine machinery or navigation systems, perform relatively dedicated functions, often have real- time requirements measured in milli-seconds, and need fewer connected nodes. These systems tend to be smaller and more self-contained when compared to other vessel networks, and carry less data volume. Because this network application integrates inexpensive sensors and actuators into larger systems, the cost per node must be far less than in other shipboard applications. This network application is addressed by NMEA 2000 (IEC 61162-3).
<br />
<br />
YouTube video: <a href="https://youtu.be/7bDLVzoGI7s" target="_blank">"How NMEA 2000 Network Works"</a><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimKL8m1qseVuALl9DAGUoUZShOG8YUWY4zeCxBvmNGbn3JIRYDWsAqaRRb5S2Mqq7fsRkbmjV_XHlHJ6igvO4zTyZ4iuH6cJg03AQIaY9svOdHavFRCB0PLpPVPxex1EPPzBMwXdIdm2iD/s1600/Typical_NMEA2000_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="553" data-original-width="1049" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEimKL8m1qseVuALl9DAGUoUZShOG8YUWY4zeCxBvmNGbn3JIRYDWsAqaRRb5S2Mqq7fsRkbmjV_XHlHJ6igvO4zTyZ4iuH6cJg03AQIaY9svOdHavFRCB0PLpPVPxex1EPPzBMwXdIdm2iD/s400/Typical_NMEA2000_Diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. A basic NMEA 2000 network.</span></i></span></td></tr>
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<span style="color: #0c343d;"><b>NMEA 2000
</b></span><br />
<br />
Architecture:<br />
<ul>
<li>Bus (parallel) wiring configuration using 4-conductor twisted- pair wire to carry power to operate the interface and data signals.</li>
<li> Linear network with end terminations and multiple short-length drop cables connecting the backbone cable to individual nodes.
</li>
</ul>
<br />
<br />
Operation:
<br />
<ul>
<li>Network access: Carrier Sense/Multiple Access/Collision Arbitration using CAN (Controller Area Network).</li>
<li>Multi-master network operation (no central control node).
</li>
</ul>
<br />
Self-configuring.
<br />
<ul>
<li>Special network tools, desirable for diagnostic purposes, are not necessary for operation.
</li>
</ul>
<br />
<br />
Size:
<br />
<br />
<ul>
<li>Physical nodes: Up to 50 connections. </li>
<li>Functional nodes: Up to 254 network addresses. </li>
<li>Length: Up to 200 meters (at 250kbits/second bit rate).
</li>
</ul>
<br />
<br />
At the basic level, and in wide use, the older <a href="https://en.wikipedia.org/wiki/NMEA_0183" target="_blank">NMEA 0183</a> (IEC 61162-1) provides serial data distribution from a single transmitter to multiple receivers. Operating at 4800 bits/second this protocol has the capability of delivering approximately ten messages, or sentences, per second. This has generally proven adequate when a single device is broadcasting data for use by other equipment. But it quickly reaches a limit when systems start to combine data. However, its use is expected to continue well into the future for simpler applications, redundant or backup data connections, and when direct device-to-device connections are needed.<br />
<br />
YouTube video: <a href="https://youtu.be/wt29QnDUFZg" target="_blank">"NMEW 2000 Network Guide Video"</a><br />
<pic here="">
</pic>
<pic here=""></pic><br />
<pic here=""><br />
<span style="color: #0c343d;"><b> </b></span></pic><br />
<pic here=""><span style="color: #0c343d;"><b>THE PHYSICAL LAYER
</b></span><br /><br />
This layer defines the electrical and mechanical aspects of the physical link between network connections, and references characteristics of the CAN devices and network interfaces to be used in NMEA 2000. </pic><br />
<pic here=""></pic><br />
<pic here=""></pic><br />
<pic here=""></pic><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDaW95NsUCfDwHOpagX1tQuLWjHbXPdpDKndqI1a18VDlkbvLGmRGmDyF23_Kxlb3PR8b7bO0RTrwr0QuFL44eNkhpsBwkYM_qWobhaV-23h6rwo09RDwFBoHZrUj4LHZdrF6ENGhdSVIo/s1600/Shipboard_Networks_and_Interfaces.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="928" data-original-width="1207" height="306" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDaW95NsUCfDwHOpagX1tQuLWjHbXPdpDKndqI1a18VDlkbvLGmRGmDyF23_Kxlb3PR8b7bO0RTrwr0QuFL44eNkhpsBwkYM_qWobhaV-23h6rwo09RDwFBoHZrUj4LHZdrF6ENGhdSVIo/s400/Shipboard_Networks_and_Interfaces.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 4. Shipboard networks and interfaces.</span></i></span></td></tr>
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<pic here=""><br /></pic>
<pic here="">The electrical characteristics of the physical layer are dictated by the following:</pic><br />
<ul>
<li><pic here="">Media access uses CAN as defined by ISO 11898, Road Vehicles - Interchange of Digital Information, Controller Area Network (CAN) for High-speed Communication. </pic></li>
<li><pic here=""></pic><pic here="">CAN utilizes dominant/recessive bit transmission.</pic></li>
<li><pic here=""></pic><pic here="">Time delays and network loading limit bit rate and network length.</pic></li>
<li><pic here=""></pic><pic here="">Differential signaling improves noise immunity.</pic></li>
<li><pic here=""></pic><pic here="">Network single-point common signal reference controls ground voltage levels and reduces RFI.</pic><br /><pic here=""></pic></li>
</ul>
<pic here=""><br />
Differential signaling indicates that powered interface circuits and a signal-reference common to all nodes on the network is required. A single-point common reference is specified in order to avoid radio-interference caused by ground loops and to maintain control of ground-voltage levels between nodes such that they remain within the common-mode range (approximately +/-2.5 Volts) of the network transceiver circuits. An important change from previous draft versions allow the use of the vessels 12-Volt battery to power the network, if the length of the backbone cable and the number of nodes are small enough, instead of the use of a more expensive regulated power supply that was previously required. </pic><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTkGcRqnhFKHlUwZfGSLRKDuX5efQtf7tR6AEgU6IXgKMT_w-OaL1MitecyWmyTXXKoB79faecP3OvCJlfPtpc8JH25CD7UX6qk350K0S1CYxNDKq8xbswzYmN8a25URuLFHojJh8GNLJX/s1600/What_is_wanted.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="651" data-original-width="929" height="280" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTkGcRqnhFKHlUwZfGSLRKDuX5efQtf7tR6AEgU6IXgKMT_w-OaL1MitecyWmyTXXKoB79faecP3OvCJlfPtpc8JH25CD7UX6qk350K0S1CYxNDKq8xbswzYmN8a25URuLFHojJh8GNLJX/s400/What_is_wanted.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 5. Typical ground loop problem solved with optically isolated network.</span></i></span></td></tr>
</tbody></table>
<pic here=""><br /></pic>
<pic here="">Single-point power and common may be distributed via the network backbone cable as previously required, or for heavier current, by dedicated twisted-pair wires to individual devices. This feature allows equipment to draw additional operating current from the network power source and to be built with minimum interface complexity. In all cases the power and common for the interface circuits must not connect to other power or ground in a network device. This isolation may be achieved in a number of ways. One is by use of isolation circuits (e.g., optoisolators) within the device, either at the interface or at specific places where the equipment connects to other devices. Another way is by assuring that no power or ground connections, other than the network power and network common, connect to the device. The latter method is suitable for equipment such as displays or sensors that have no interfaces other than with the NMEA 2000 network, can draw all of their operating current from the network source, and have isolated packaging and mounting designs.
<br /><br />
The figure below illustrates a typical physical layer interface circuit using available transceiver integrated circuits meeting the requirements of ISO 11898. Ground isolation, illustrated with optoisolators, is shown between the network and the CAN controller and other device circuits (e.g., microprocessor and other circuits). However, as pointed out above, isolation from other circuits may be accomplished by other means. </pic><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaSXlIrR969J1bEoPeZkvK8glHBeFv6zbffMyqQ0VHi10wqQQKm8Wl83dXbAm9OmfeF6MjGySKQKgpsrXM4J8kb8adQRivBNkLYLzo1dg2aBK2qAwXKeihok1fxVS-rasqSkpmzHGWLm2h/s1600/Typical_Isolated_Network_Interface.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="485" data-original-width="929" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaSXlIrR969J1bEoPeZkvK8glHBeFv6zbffMyqQ0VHi10wqQQKm8Wl83dXbAm9OmfeF6MjGySKQKgpsrXM4J8kb8adQRivBNkLYLzo1dg2aBK2qAwXKeihok1fxVS-rasqSkpmzHGWLm2h/s400/Typical_Isolated_Network_Interface.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 6. Typical optically isolated network interface.</span></i></span></td></tr>
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<pic here=""></pic><br />
<br />
<pic here="">The illustrated transceiver circuit requires regulated +5 Volt power that is provided by the Regulator and Protection circuits. The purpose of the protective circuits is to prevent damage to the regulator and the interface circuits from overvoltage and reverse voltage. No permanent damage should result from a voltage level of +/-18.0 Volts or less applied between any two wires in the interface for an indefinite period of time or from miswiring the interface lines in any combination.
</pic><br />
<pic here=""></pic><br />
<pic here=""><br />
<pic here="">YouTube video: <a href="https://youtu.be/jYdfH0vhBuc" target="_blank">"Tips - Installing a NMEA 2000 Backbone on a Boat"</a> </pic></pic><br />
<br />
<br />
<pic here=""><pic here=""><span style="color: #0c343d;"><b>THE MAIN POINTS OF THE PHYSICAL LAYER
</b></span><br /><br />
<u><i>Environmental and Radio Frequency Interference
</i></u><br /><br />
NMEA 2000 implementations must meet the Durability and Resistance to Environmental Conditions described in Section 8 of IEC 60945 and meet the Unwanted Electromagnetic Emissions and the Immunity to Electromagneic Environment conditions of Sections 9 and 10 of IEC 60945. Shielded cables are recommended, and may be necessary to meet these latter requirements.
<br /><br />
<u><i>Ground Isolation
</i></u><br /><br />
AC and DC isolation is required between all of the terminals at the interface connector, with the network cables disconnected, and any other ships ground or voltage sources. As discussed above this can be accomplished with isolation devices such as opto-isolators or by wiring and packaging design. For most applications, except those with very low power needs, the isolated interface is the preferred implementation.
<br />
<br />
<u><i>Network Signaling
</i></u><br /><br />
The two signal lines carry differential signals measured with respect to the network power common. The signals on the network represent two states: Dominant state or Logic 0, and Recessive state or Logic 1, during the transmission of the Dominant state by one or more nodes the state of the network is Dominant. The interface must be designed so that the signal lines are in the Recessive state when node power is off.
<br /><br />
The AC and DC voltage parameters of the network signals are specified by ISO 11898. The nominal voltage levels are:
<br /><br />
Dominant state:</pic></pic><br />
<pic here=""><pic here=""> CAN+ = 3.5V CAN- = 1.5V V diff = CAN+ - CAN- = 2.0V
<br /><br />
Recessive state:</pic></pic><br />
<pic here=""><pic here=""> CAN+ = 2.5V CAN- = 2.5V V diff = CAN+ - CAN- = 0.0V
<br /><br />
Common Mode range: Difference in network common voltage between nodes:</pic></pic><br />
<pic here=""><pic here=""> -2.5 to +2.5 Volts
<br /><br />
<u><i>Network Power
</i></u><br /><br />
The interface circuits must operate over the range of 9.0 to 16.0 Volts DC. The voltage for the interface can either be supplied from the network backbone cable or supplied by a dedicated twisted-pair power cable connected only between a single node and the network power source (the vessels battery or one regulated power supply). The amount of current delivered by the network cable is limited. When a dedicated power connection is used the node is allowed to draw additional current but the connections must be labeled, and physically separated and isolated from other power and ground connections. Under no condition may the node power or ground be connected to other power or ground in the equipment.
<br /><br />
To aid in planning network installations manufacturers are required to specify the power rating for each connected device as a load equivalency number. The actual power source for the network can be either a single-point connection to the vessels battery or one or more isolated power supplies distributed along the network. The size and routing of the cables must be carefully considered. As the number of nodes with high load equivalency number increase, DC voltage loss in the cables quickly becomes the limiting factor for network length rather than the propagation time for the signals. For networks of shorter length and with a lower number of connected devices the ships battery may be used to power the network nodes directly. In place of the battery, electrically isolated regulated power supplies may be used if it is necessary to extend the size of the network.
<br /><br />
<u><i>Cables and Connectors
</i></u><br /><br />
Two methods are provided for connecting to the network backbone cable: a standard connector or barrier strips. These connections are used for connecting segments of backbone cable together, for connecting terminations at the two ends of the cable, for connecting the network power source, and for connecting nodes. The drop cable, the short cable running from the backbone connection to the node equipment, may connect to the equipment anyway the manufacturer chooses. It is the connections at the backbone that are controlled by the NMEA 2000 standard. </pic></pic><br />
<pic here=""><pic here=""><br /></pic></pic>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiQWAQOc5BaF3oiEMtJVA8bu8yI1oH0CrBCrb-L8M5_6POJRfXXqJqPlAJp6N9mmF46wFNDWYCu-IrSjqB7sA-CVvK0eo0-bNIOeAx9Nn7AO1NcsSZqufLXXiFhPidgjZF9Q2d8FqYqJMl/s1600/DSCN0785.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiQWAQOc5BaF3oiEMtJVA8bu8yI1oH0CrBCrb-L8M5_6POJRfXXqJqPlAJp6N9mmF46wFNDWYCu-IrSjqB7sA-CVvK0eo0-bNIOeAx9Nn7AO1NcsSZqufLXXiFhPidgjZF9Q2d8FqYqJMl/s400/DSCN0785.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 7. Typical "star" configuration. (The actual network is a short stub and all the devices connect to it with longer cables.)</span></i></span></td></tr>
</tbody></table>
<pic here=""><pic here=""></pic></pic><br />
<br />
<pic here=""><pic here="">Barrier strips are only recommended when the connections are made in a protected location, or when they are installed in a weatherproof enclosure, thus meeting the requirements for Resistance to Environmental Conditions for exposed equipment in IEC 60945. Barrier strips positions must be either numbered or color-coded in accordance with the definitions in the standard.
<br /><br />
The connector selected for the NMEA 2000 backbone is a 5-pin type used in industrial networks and is available from multiple sources (including Molex, Turck Inc., Methode Components, and Daniel Woodhead Company). The connector is available as a 3-port T connector, cable-end connector, bulkhead-mount connector and special configurations with internal termination resistors.
<br /><br />YouTube video: </pic></pic><a href="https://youtu.be/0DTKC4MIJ1U" target="_blank">"How to Install NMEA 2000 Boat Electronics System<pic here=""><pic here="">"</pic></pic></a><br />
<pic here=""><pic here=""></pic></pic><br />
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<pic here=""><pic here="">Cable specified for the network must meet both the characteristic impedance and propagation delay requirements for use as a transmission line, and also the wire-size needs of the DC power distribution function of the cable. The cable lengths on the network, the number of nodes connected, the distribution of the nodes, and the location of the power source connection(s) into the backbone cable determine the actual cable requirements in a particular installation. Two cable sizes are specified and can be used as needed in an installation. NMEA 2000 Heavy cable is 5-wire consisting of two shielded- twisted-pairs and a common shield drain wire. The wire pairs are No. 16 AWG (1.33 sq. mm) for DC power and No. 18 AWG (0.83 sq. mm) for signals. NMEA 2000 Light cable uses No. 22 (0.38 sq. mm) and No. 24 (0.24 sq. mm) respectively.
</pic></pic><br />
<pic here=""><pic here=""></pic></pic><br />
<pic here=""><pic here="">The cable specified has a defined color code, in the event that these colors are not available the substitute cable must be marked according to the standard."</pic></pic><br />
<pic here=""><pic here=""> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis19iSIr5zJsMRkhiRK7AUsXUiI5Rq5SrOEYioykwirNFmsCks0RRzUSs7BGsRgOexJDT3fFtnoB8G6fq2d6QxNUWCDZIaI_JHZb4Mbz6TLc9YhKD-u6CltkAOAwKtXmgSOZUkRsT_5-eV/s1600/NMEA-2000-micro-c-connector-pin-assignments-orientation.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="128" data-original-width="357" height="114" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis19iSIr5zJsMRkhiRK7AUsXUiI5Rq5SrOEYioykwirNFmsCks0RRzUSs7BGsRgOexJDT3fFtnoB8G6fq2d6QxNUWCDZIaI_JHZb4Mbz6TLc9YhKD-u6CltkAOAwKtXmgSOZUkRsT_5-eV/s320/NMEA-2000-micro-c-connector-pin-assignments-orientation.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 8. Typical connectors, running power and signal.</span></i></span></td></tr>
</tbody></table>
</pic></pic><br />
<br />
<span style="color: #274e13;"><i><pic here=""><pic here=""> ["</pic></pic></i></span><pic here=""><pic here=""><span style="color: #274e13;"><i>The solution to ground loop noise is to break the ground loop, or
otherwise prevent the current from flowing. The diagrams show several
solutions which have been used
" (Read more about <a href="https://en.wikipedia.org/wiki/Ground_loop_(electricity)" target="_blank">ground loops</a>.]</i></span></pic></pic><pic here=""><pic here=""> </pic></pic><br />
<br />
<span style="color: #274e13;"><i>[Below is an interesting video about the NMEA 2000 networking problems. In this case it is about the fact that there can only be one terminating resistor in the network at each end of it (2 all together). (And also other installations problems.)]</i></span><br />
<br />
YouTube video: <a href="https://youtu.be/gHe8HYuUUMY" target="_blank">"Mast Climbing Madness (Sailing Giraffe)"</a><br />
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<pic here=""><pic here=""><span style="color: #0c343d;"><b>RESOURCES
</b></span></pic></pic><br />
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<pic here=""><pic here=""><br />
/1/ Cassidy, Frank - "NMEA 2000 Explained - The Latest Word" - 1999 </pic></pic><br />
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<br />
<pic here=""><pic here="">/2/ Wikipedia<br /><br />
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<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-1367549987612784992018-08-10T00:04:00.001+01:002018-08-10T00:12:42.368+01:00JB11 Latest JetpackLooks like Jetpack people have again created a new version of their "real jetpack", real meaning that it really uses jets and not rockets like some earlier versions of jetpacks did.<span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><br /></span>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeCMYKc6d9Dg5Eu7SaKfc3ZSAsRpdh89g2ifvN04hfIrhDYShuIIOCaL2AfNu4FdzKjPzU488YNHZUWXCpOulYEXhUNhq6OXi4I67wuGt4pCAZDZZkbM27jmJt5_upBQrs5-WsStpaCzM-/s1600/JB11.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="699" data-original-width="423" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjeCMYKc6d9Dg5Eu7SaKfc3ZSAsRpdh89g2ifvN04hfIrhDYShuIIOCaL2AfNu4FdzKjPzU488YNHZUWXCpOulYEXhUNhq6OXi4I67wuGt4pCAZDZZkbM27jmJt5_upBQrs5-WsStpaCzM-/s400/JB11.png" width="241" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 1. Jetpack JB-11 uses multiple turbines for additional redundance. It can fly with one turbine inoperative.</i></span> </td></tr>
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<span style="background-color: white; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><span style="color: #0c343d;"><br /></span></span>
<span style="background-color: white; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><span style="color: #0c343d;"><br /></span></span>
<b><span style="color: #0c343d;">VIDEOS:</span></b><br />
<span style="background-color: white;"><span style="color: #0c343d;"><b><br /></b></span></span>
YouTube video: <a href="https://youtu.be/Kh1x6q21-HU" target="_blank">"World’s Most Advanced JetPack, the JB11 First EVER Flight at Goodwood Festival of Speed 2018"</a><br />
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<span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><br /></span>
<span style="background-color: white; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><b><span style="color: #0c343d;">RESOURCES:</span></b></span><br />
<span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"><br /></span>
<span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;">/1/ </span><span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;">h<a href="ttp://www.jetpackaviation.com/">ttp://www.jetpackaviation.com/</a></span></span><br />
<span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;"><br /></span></span>
<span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;">/2/ YouTube</span></span><br />
<span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;"><br /></span></span>
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<span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;">* * *</span></span></div>
<span style="color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif;"><span style="font-size: 12.61px; line-height: 18.915px;"><br /></span></span>Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-5493912261746601492018-08-09T22:49:00.000+01:002018-08-09T23:30:09.894+01:00Mars 2020 Rover<i><span style="color: #274e13;">[NASA will send a new rover to Mars year 2020 and also return some samples from Mars to Earth. The rover is similar to the Curiosity rover already there. Here are some facts about it - the video link at the end of this post is rather informative. /1/ /2/]</span></i><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvdU3w47GsCJXDRhX1gb9rDxSviz6RvFS4IhJMBVd2NEcVy3uD1lrXJN6ktZp9MNLqKRJUJI-RShCcse7Qo6sqmC_6uR_he-YEmthKGSfc0wl6LnlWG426i3dADQn3W3cHQA9wmJKvLg40/s1600/Computer-Design_Drawing_for_NASA%2527s_2020_Mars_Rover.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="975" data-original-width="1600" height="243" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvdU3w47GsCJXDRhX1gb9rDxSviz6RvFS4IhJMBVd2NEcVy3uD1lrXJN6ktZp9MNLqKRJUJI-RShCcse7Qo6sqmC_6uR_he-YEmthKGSfc0wl6LnlWG426i3dADQn3W3cHQA9wmJKvLg40/s400/Computer-Design_Drawing_for_NASA%2527s_2020_Mars_Rover.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 1. Computer-Design Drawing for NASA's 2020 Mars Rover</i></span></td></tr>
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<a name='more'></a><br />
"The as-yet unnamed <a href="https://en.wikipedia.org/wiki/Mars_2020" target="_blank">Mars 2020 mission</a> was announced by NASA on 4 December 2012 at the fall meeting of the <a href="https://en.wikipedia.org/wiki/American_Geophysical_Union" target="_blank">American Geophysical Union</a>in San Francisco. The rover's design is derived from the <a href="https://en.wikipedia.org/wiki/Curiosity_(rover)" target="_blank">Curiosity rover</a>, and will use many components already fabricated and tested, but it will carry different scientific instruments and a <a href="https://en.wikipedia.org/wiki/Core_drill" target="_blank">core drill</a>."<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIxGXM1NptY-5prOGeDiGVC-A8Cjh6tmxXq63a9DIaSIfqvrTxoEt5ula3ijssAU71gfzQs9A7Zp-o9DFEJS0pWigsDXhxWvSJry1x-Eoh4u51EFCCMPC6lisNmMCO5aO5EpOpbSHQsBZw/s1600/Mars_sample_returnjpl.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="996" data-original-width="960" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIxGXM1NptY-5prOGeDiGVC-A8Cjh6tmxXq63a9DIaSIfqvrTxoEt5ula3ijssAU71gfzQs9A7Zp-o9DFEJS0pWigsDXhxWvSJry1x-Eoh4u51EFCCMPC6lisNmMCO5aO5EpOpbSHQsBZw/s400/Mars_sample_returnjpl.jpg" width="385" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 2. Mars Sample Return is a proposed mission to return samples from the surface of Mars to Earth. The mission would use robotic systems and a Mars ascent rocket to collect and send samples of Martian rocks, soils and atmosphere to Earth for detailed chemical and physical analysis.</i></span></td></tr>
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"A key mission requirement for this rover is that it must help prepare NASA for its <a href="https://en.wikipedia.org/wiki/Mars_sample-return_mission" target="_blank">Mars sample-return mission</a> (MSR) campaign, which is needed before any <a href="https://en.wikipedia.org/wiki/Human_mission_to_Mars" target="_blank">crewed mission</a> takes place. Such effort would require three additional vehicles: an orbiter, a fetch rover, and a Mars ascent vehicle (MAV).</div>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg23Ti9HOGy12l4dfZ7GZ4IREmirxL0EnVpMymm6WDc90z7GVwwLXeQZ5ZPGokD9Ug8L8UfmEMv4gyD2neov0IUbCl7CqUQwGwlg2dxDlaWI4wNZQo4-HJtI9Q75O-iwuCIhiddLuJ0FTo1/s1600/PIA19672-Mars2020Rover-ScienceInstruments-20150610.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg23Ti9HOGy12l4dfZ7GZ4IREmirxL0EnVpMymm6WDc90z7GVwwLXeQZ5ZPGokD9Ug8L8UfmEMv4gyD2neov0IUbCl7CqUQwGwlg2dxDlaWI4wNZQo4-HJtI9Q75O-iwuCIhiddLuJ0FTo1/s400/PIA19672-Mars2020Rover-ScienceInstruments-20150610.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 3. Mars 2020 Rover - Science Instruments</i></span></td></tr>
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Dozens of samples would be collected and cached by the Mars 2020 rover, and would be left on the surface of Mars for possible later retrieval. A "fetch rover" would retrieve the sample caches and deliver them to a Mars ascent vehicle (MAV). In July 2018 NASA contracted <a href="https://en.wikipedia.org/wiki/Airbus" target="_blank">Airbus</a> to produce a "fetch rover" concept. The MAV would launch from Mars and enter a 500 km orbit and <a href="https://en.wikipedia.org/wiki/Space_rendezvous" target="_blank">rendezvous</a> with a <a href="https://en.wikipedia.org/wiki/Mars_2022_orbiter" target="_blank">new Mars orbiter</a>. The sample container would be transferred to an Earth entry vehicle (EEV) which would bring it to Earth, enter the atmosphere under a parachute and hard-land for retrieval and analyses in specially designed safe laboratories."<br />
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<br />
<b><span style="color: #0c343d;">VIDEOS</span></b></div>
<div>
<br />
YouTube video: <a href="https://youtu.be/0M7VvnaoIVY" target="_blank">"The Mars 2020 Rover (collab with Fraser Cain) | Answers With Joe"</a><br />
<br />YouTube video: <a href="https://youtu.be/RNnJBKR9lqY" target="_blank">"Mars sample return"</a><div>
<br />YouTube video: <a href="https://youtu.be/BCAhhJmMB9M" target="_blank">"Mars Sample Return Simulation : sample retrieval and transfer"</a><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; margin: 0px; text-transform: none; white-space: normal; word-spacing: 0px;">
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<br />YouTube video: <a href="https://youtu.be/EE4ThqABoMo" target="_blank">"Mars Rover Sample Return Mission (1988)"</a></div>
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<div>
<b><span style="color: #0c343d;">RESOURCES</span></b></div>
<div>
<br /></div>
<div>
/1/ Wikipedia <a href="https://en.wikipedia.org/wiki/Mars_2020" target="_blank">Mars 2020 Mission</a></div>
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/2/ YouTube</div>
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Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-63844624154974056772018-04-02T04:08:00.000+01:002018-04-02T18:59:40.896+01:00Apollo On-board Guidance History (Part 16, Apollo Control Systems)<i><span style="color: #274e13;">[This article is based mainly on D.G. Hoag's paper about Apollo's on-board Guidance, Navigation, and Control System history /10/]</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
APOLLO ON-BOARD GN(et)CS HISTORY /10/<br />
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<i><span style="color: #4c1130;">"This account is written from the point of view of one who experienced the hectic but exciting years. An enormous amount of material has been left out for practical reasons, and many worthy names regretfully remain unmentioned. Technical details have been deliberately played down: they can be found in the bibliography. The overall message is simple: In an incredible and audacious task, the landing of men on the moon, the guidance equipment for the mission was created out of primitive principles, prolific imagination, and a lot of hard work." -- Hoag, D.G.
</span></i><br />
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<b><span style="color: #0c343d;">The Beginnings /10/
</span></b><br />
<br />
"The forerunner of the Apollo guidance, navigation, and control system (GNetCS)), is found in an unmanned spacecraft and mission study started in 1957 by the <a href="https://en.wikipedia.org/wiki/Charles_Stark_Draper_Laboratory" target="_blank"><b><i>Instrumentation Laboratory at MIT</i></b></a> under a contract with the <a href="https://en.wikipedia.org/wiki/Air_Force_Satellite_Control_Facility" target="_blank"><b><i>Air Force Ballistic Missile Division</i></b></a>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbMCm7rW2jVy2y605X7H8dqqv22K3-fQkWNNQMhEIosaPkJ-SBSj7QBOD6Sr5QPRGO7XN5Sanbz_qFD4gJdIOXo2ycZVqbZC4ugLZm8jIA0DWDVByxxyzYyQ4vmgT5AM_vo4hyCcKUMplk/s1600/Trageser_Laning_Battin.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="652" data-original-width="615" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbMCm7rW2jVy2y605X7H8dqqv22K3-fQkWNNQMhEIosaPkJ-SBSj7QBOD6Sr5QPRGO7XN5Sanbz_qFD4gJdIOXo2ycZVqbZC4ugLZm8jIA0DWDVByxxyzYyQ4vmgT5AM_vo4hyCcKUMplk/s400/Trageser_Laning_Battin.png" width="376" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Milton Trageser (left), Hal Laning and Richard Battin</i></span></td></tr>
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<a name='more'></a><br />
The small Instrumentation Lab team for this study, led by <b><i>Milton Trageser</i></b> and supported by <a href="https://en.wikipedia.org/wiki/Avco" target="_blank"><b><i>AVCO Corporation</i></b></a>, the <a href="https://en.wikipedia.org/wiki/MIT_Lincoln_Laboratory" target="_blank"><b><i>MIT Lincoln Laboratory</i></b></a>, and <a href="https://en.wikipedia.org/wiki/Thiokol" target="_blank"><b><i>Thiocol Chemical Corporation</i></b></a>, produced a complete design of a 150 kg autonomous spacecraft which would take a close-up height resolution photo of Mars.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8QpXczKP6LPzjAg1n_qo2AM_DR4scjkiT1nW8D2G8tNjww_T_u9Nkp9OoNZ9y0LuHfH9vyPn_Puk4-7BN4DqcrTp705NjZKnEzaSVpZrSoEG16QrRWdSEFdIZw-lRVlnR2-0XPtrWV0eR/s1600/DickBattin%2540380x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="380" data-original-width="380" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8QpXczKP6LPzjAg1n_qo2AM_DR4scjkiT1nW8D2G8tNjww_T_u9Nkp9OoNZ9y0LuHfH9vyPn_Puk4-7BN4DqcrTp705NjZKnEzaSVpZrSoEG16QrRWdSEFdIZw-lRVlnR2-0XPtrWV0eR/s400/DickBattin%2540380x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i><span style="color: #cc0000; font-size: small;">Dr. Richard Battin</span></i></td></tr>
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<i><span style="color: #274e13;">YouTube video:</span></i> <a href="https://youtu.be/ieiEoTo8-XY" target="_blank"><b><i>"Battin: A Funny Thing Happened on the way to the Moon"</i></b></a><br />
<br />
This Mars prope had several new features, later incorporated in the Apollo system, including a space sextant to make periodic navigation angle measurements between pairs of celestial objects: the sun, the near planets, and selected stars.<br />
<br />
The guidance technique utilized original formulations designed by <b><i><a href="https://en.wikipedia.org/wiki/J._Halcombe_Laning" target="_blank">Dr. J. Halcombe Laning</a></i></b> and <b><i><a href="https://en.wikipedia.org/wiki/Richard_Battin" target="_blank">Dr. Richard Battin</a></i></b> to operate a small rocket at appropriate times to put the spacecraft on a corrected trajectory which would utilize the Martian gravity during the close passage and thereby send the spacecraft with its Mars picture on a path back to Earth for physical recovery.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUc-e0eTT5WqLkaFy7IesXI3C7hWgmwdEOtyGpLeGzLITnulOiW6hR8C3cL8AV7Fq6SmTXZtLdv_GTDJn46qz59TOnMvnqikqdm4KI9HOEPyJPg2G7rApBtX1B_p5HvtDN5mIDGDu4LnTl/s1600/HalLaning%2540380x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="380" data-original-width="380" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUc-e0eTT5WqLkaFy7IesXI3C7hWgmwdEOtyGpLeGzLITnulOiW6hR8C3cL8AV7Fq6SmTXZtLdv_GTDJn46qz59TOnMvnqikqdm4KI9HOEPyJPg2G7rApBtX1B_p5HvtDN5mIDGDu4LnTl/s400/HalLaning%2540380x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Halcombe Laning</i></span></td></tr>
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<br />
Spacecraft attitude control was to be accomplished by torquing small <a href="https://en.wikipedia.org/wiki/Reaction_wheel" target="_blank"><b><i>momentum wheels</i></b></a> with the use of the solar pressure force on adjustable sun vanes to drive the average speed of these wheels toward zero.<br />
<br />
Overall autonomous operation was managed on-board by a small general purpose digital computer configured by its designer, <b><i>Dr. Raymond Alonso</i></b>, for very low power drain except at the occasional times needing fast computation speed. A special feature of this computer was the pre-wired, read-only memory called a <a href="https://en.wikipedia.org/wiki/Core_rope_memory" target="_blank"><b><i>core rope</i></b></a>, a configuration of particularly high storage density requiring only one magnetic core per word of memory.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdFa9erq0ltRaxPTBWYO37qpqE-Pzq1jYrBp2JOmvvCQ9_AkH48XoF_jwWrM45_XlpSJ7O3Yn7AeocnS_xshKs-_asnNy9pnVnpIJlt_sHNpKBlRBxTxsDCMLh-Ur2bpKl-6KpPVqPEV7n/s1600/Dr_Raymond_Alonso.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="757" data-original-width="951" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdFa9erq0ltRaxPTBWYO37qpqE-Pzq1jYrBp2JOmvvCQ9_AkH48XoF_jwWrM45_XlpSJ7O3Yn7AeocnS_xshKs-_asnNy9pnVnpIJlt_sHNpKBlRBxTxsDCMLh-Ur2bpKl-6KpPVqPEV7n/s400/Dr_Raymond_Alonso.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Raymond Alonso in the MIT film <a href="https://youtu.be/YIBhPsyYCiM" target="_blank">"Computer for Apollo"</a></i></span></td></tr>
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A four volume report of this work was published in July, 1959, and presented to the Air Force Sponsors. However, since the Air Force was disengaging from civilian space development, endeavors to interest NASA were undertaken.<br />
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<a href="https://en.wikipedia.org/wiki/Guyford_Stever" target="_blank"><b><i>Dr. H. Guyford Stever</i></b></a>, then an MIT professor, arranged a presentation with <a href="https://en.wikipedia.org/wiki/Hugh_Latimer_Dryden" target="_blank"><b><i>Dr. Hugh Dryden</i></b></a>, NASA Deputy Administrator, which took place on September 15. (Dryden did not hear their talks. The MIT Laboratory team was upstaged by the presence of <a href="https://en.wikipedia.org/wiki/Nikita_Khrushchev" target="_blank"><b><i>Premier Kruschev</i></b></a> that day visiting in Washington.)
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipEX8uTbOH-vVp1YxY9lFqw3bHld3s4j6FeOuMW6nQJ_1UtRz8ne9lPjrSx8jUZoVN7YZnpH7dQGEa-NmFozviYXt8HU14CIyjysKyGS7aZYYhhWpqAZj86H9Cihq4pAwCYhg-O4VOpRkz/s1600/NACA%2527s_Special_Committee_on_Space_Technology_1958.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1200" data-original-width="1500" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipEX8uTbOH-vVp1YxY9lFqw3bHld3s4j6FeOuMW6nQJ_1UtRz8ne9lPjrSx8jUZoVN7YZnpH7dQGEa-NmFozviYXt8HU14CIyjysKyGS7aZYYhhWpqAZj86H9Cihq4pAwCYhg-O4VOpRkz/s400/NACA%2527s_Special_Committee_on_Space_Technology_1958.png" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>NACA's Special Committee on Space Technology, called the Stever Committee after its chairman, Guyford Stever, meets at Lewis, May 26, 1958.<br />Left to right (1 - 16), <br />(1) Edward R. Sharp, Director of Lewis Laboratory;<br /> (2) Colonel Norman C Appold, US Air Force,<br /> (3) Abraham Hyatt, Bureau of Aeronautics, Navy;<br />(4) Hendrik W Bode, Director, Bell Telephone Labs.;<br /> (5) W Randolph Lovelace II, Lovelace Foundation.,<br /> (6) S. K Hoffman, General Manager, Rocketdyne Division, NAA;<br /> (7) Milton U Clauser, Director, The Ramo-Wooldridge Corp.,<br />(8) H. Julian Allen, Chief, High Speed Flight Research, NACA Ames,<br />(9) Robert R. Gilruth, Assistant Director, NACA Langley,<br />(10) J. R. Dempsey, Manager. Convair-Astronautics;<br />(11) Carl B. Palmer, Secretary to Committee, NACA Headquarters,<br />(12) H. Guyford Stever, Chairman, Associate Dean of Engineering, MIT,<br />(13) Hugh L. Dryden (ex officio), Director, NACA;<br />(14) Dale R. Corson, Department of Physics, Cornell University;<br />(15) Abe Silverstein, Associate Director, NACA Lewis;<br />(16) Wernher von Braun, Director, Army Ballistic Missile Agency.</i></span></td></tr>
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On November 10, 1959 NASA sent a letter of intent to contract the Instrumentation Laboratory for a $50,000 study to start immediately. The stated purpose was that this study would contribute to the efforts of <a href="https://en.wikipedia.org/wiki/Jet_Propulsion_Laboratory" target="_blank"><b><i>NASA's Jet Propulsion Laboratory</i></b></a> in conducting unmanned space missions to Mars, Venus, and the Earth's moon scheduled in Vega and Centaur missions in the next few years.<br />
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A relationship between MIT and JPL did not evolve. JPL's approach to these deep space missions involved close ground base control with their large antenna tracking and telemetry systems, considerably different from the <b><i>onboard self sufficiency</i></b> method which the MIT group advocated and could best support.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-tIFtbDcTefOxARHGkTiue7xXs_mMvff6I1ZL1jrfg_vMzqGb-b7HegLpvnulxR7hL2E3R-2ZQFQZJcr3bgetRWf9C7Sa5TELR-mZf7j3yRu4C2bVNkzueMWFK9PQmTsnLREYOSFEyTUZ/s1600/Atlas-Centaur-AC3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="973" data-original-width="1574" height="246" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-tIFtbDcTefOxARHGkTiue7xXs_mMvff6I1ZL1jrfg_vMzqGb-b7HegLpvnulxR7hL2E3R-2ZQFQZJcr3bgetRWf9C7Sa5TELR-mZf7j3yRu4C2bVNkzueMWFK9PQmTsnLREYOSFEyTUZ/s400/Atlas-Centaur-AC3.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Atlas-Centaur AC3</i></span></td></tr>
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The Instrumentation Laboratory report on the NASA study appeared in four volumes in April, 1960. It described the design of a 35 kg pod comprising a self contained guidance, navigation and control system intended for mounting on Centaur vehicles to support a variety of space missions.<br />
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A <b><i>space sextant</i></b>, similar to but improved over the Mars probe study, was to make the autonomous navigation measurements.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNVxaqXfpPct3th-xtMoAf0rAW3rKGiywm5SQTdJX7q36kjbnr00H2QiXViTxqwrC4JjlkD1OSA8ZMu4E_YuCIgDOAkw406MD7rbi2l5MDTNFYcaxPAdLU4HykdyqXNX8UtLsDUjJzqtRw/s1600/sextant_idea.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="748" data-original-width="904" height="330" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNVxaqXfpPct3th-xtMoAf0rAW3rKGiywm5SQTdJX7q36kjbnr00H2QiXViTxqwrC4JjlkD1OSA8ZMu4E_YuCIgDOAkw406MD7rbi2l5MDTNFYcaxPAdLU4HykdyqXNX8UtLsDUjJzqtRw/s400/sextant_idea.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Schematic of a sextant. By adjusting the index arm and mirror the user can superimpose the horizon and star and then read the angle on the scale and micrometer.</i></span></td></tr>
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<i><span style="color: #274e13;">[A space sextant is very much similar to a normal sextant. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of <a href="https://en.wikipedia.org/wiki/Celestial_navigation" target="_blank">celestial navigation</a>. ]</span></i><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiecbucurSOWpLz11AI0a-ikTjKntcGJXFiqv2VJ8v_MgmYwLTDZQ00Ytiw8PY275Sk398PIR1Fms4UGApQlMK3uCtGIDnEWFSKYifz3DCqfEapUqdRC70PdxKqUVcaQQpkIT5wiWJDUKdT/s1600/Atlas-Centauri-move.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="733" data-original-width="895" height="327" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiecbucurSOWpLz11AI0a-ikTjKntcGJXFiqv2VJ8v_MgmYwLTDZQ00Ytiw8PY275Sk398PIR1Fms4UGApQlMK3uCtGIDnEWFSKYifz3DCqfEapUqdRC70PdxKqUVcaQQpkIT5wiWJDUKdT/s400/Atlas-Centauri-move.png" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The first Atlas-Centaur, Vehicle F-1 (Atlas 104D and Centaur F-1), arrived at Cape Canaveral in October 1961 and was erected at the newly completed LC-36A, a pad built specifically for A/C flights. </i></span></td></tr>
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Two single axis <a href="https://en.wikipedia.org/wiki/Gyroscope" target="_blank"><b><i>gyros</i></b></a> and an <a href="https://en.wikipedia.org/wiki/Accelerometer" target="_blank"><b><i>accelerometer</i></b></a> were part of the design for angle and velocity change measurement. A wide ranging examination of deep space trajectory studies was reported by Laning and Battin to show needed injection velocities, transfer times, and target planet approach paths.<br />
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A variable time-of-arrival guidance scheme was formulated by Battin to improve the maneuver fuel use. He also worked out strategies for optimum navigation measurement schedules with the sextant. Other features showed the development of ideas started in the Mars probe. Particularly the configuration of the digital computer was refined by Alonso and Laning."
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<i><span style="color: #274e13;">Video:</span></i> <a href="https://youtu.be/_WP0wbeSce8" target="_blank"><b><i>"First Atlas Launch and Blowup 1957"</i></b></a><br />
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<b><span style="color: #0c343d;">Early Apollo /10/
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"The inability of the MIT Instrumentation Laboratory team and its ideas to find a place in the unmanned deep space missions continued through the summer of 1960.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_whAGjF5PRUPjNvmjPESGkS_yd75F4L5syhsk_ZUhLW8lxS2u4olUFBB96SxWSJDsagBDdfbQMqT6vXD2_45y6qK6S2XQgyu1LZNTBEdHBmZZjB1PQNdeXysyhGWl2vi6kvq6qyDLRiDi/s1600/Charles_Draper_and_Apollo_CM_Space_Sextant_and_Telescope.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="584" data-original-width="406" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_whAGjF5PRUPjNvmjPESGkS_yd75F4L5syhsk_ZUhLW8lxS2u4olUFBB96SxWSJDsagBDdfbQMqT6vXD2_45y6qK6S2XQgyu1LZNTBEdHBmZZjB1PQNdeXysyhGWl2vi6kvq6qyDLRiDi/s400/Charles_Draper_and_Apollo_CM_Space_Sextant_and_Telescope.jpg" width="276" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Charles Draper by the Apollo CM space sextant and telescope prototype</i></span></td></tr>
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In November 1960, <a href="https://en.wikipedia.org/wiki/Charles_Stark_Draper" target="_blank"><b><i>Dr. C. S. Draper</i></b></a>, Director of the Instrumentation Laboratory, had conversations about this and about possible participation in manned space missions with <b><i>Dr. Harry J. Goett</i></b>, Director of NASA's Goddard Laboratories and Chairman of the NASA Research Steering Committee on Manned Space Flight.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeoi57DsYUD7Upo4w43rCxS8SgnHa45iy9bluxPKPFxSwNFbzkF0ZKFahivHI_RyJQWv1shmjbaVUjHtxKfQCb_qtmJa6isjrp215-mi39wKxA49yZB3HmlMLgA-oq8CForpqTy4rpaHAg/s1600/Harry_Goett_NASA.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="504" data-original-width="350" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgeoi57DsYUD7Upo4w43rCxS8SgnHa45iy9bluxPKPFxSwNFbzkF0ZKFahivHI_RyJQWv1shmjbaVUjHtxKfQCb_qtmJa6isjrp215-mi39wKxA49yZB3HmlMLgA-oq8CForpqTy4rpaHAg/s400/Harry_Goett_NASA.jpg" width="277" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small; text-align: start;"><i><span style="color: #cc0000;">Dr. Harry J. Goett, was the Goddard Center's first director, 1959-1965. During his tenure as Director, some 35 Goddard satellite projects, carrying over 100 scientific experiments, were successfully placed into orbit.</span></i></span></td></tr>
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The <b><i>manned lunar mission</i></b> had been under NASA consideration for some time and was being examined by Goett's committee. The <a href="https://en.wikipedia.org/wiki/Space_Task_Group" target="_blank"><b><i>Space Task Group</i></b></a> at NASA's Langley Research Center formed in October, 1958, was working on <a href="https://en.wikipedia.org/wiki/Project_Mercury" target="_blank"><b><i>Project Mercury</i></b></a> but was by this time considerably involved in the proposed moon mission.<br />
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The name <b><i>Apollo</i></b> was announced in July, 1960, and in August NASA stated its intent to fund six month feasibility study contracts which were later in the year awarded to <a href="https://en.wikipedia.org/wiki/General_Dynamics" target="_blank"><b><i>General Dynamics/Convair</i></b></a>, <a href="https://en.wikipedia.org/wiki/General_Electric" target="_blank"><b><i>General Electric Company</i></b></a>, and <a href="https://en.wikipedia.org/wiki/Martin_Marietta" target="_blank"><b><i>The Martin Company</i></b></a>.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRKrlX_kW-kiTEiSEwcibSntjrap2hA1MI4yZkKaDvv4AsekXRSyAp9KHm2oxmJvhNu-HCBgM7_3ca6T1ZSSCVled_jtKUExnoLNbxGnh39_5SwnOB2Q2FHaqjaV7E9ILdqFSzRhyZjQji/s1600/GPN-2002-000114.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1222" data-original-width="1536" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRKrlX_kW-kiTEiSEwcibSntjrap2hA1MI4yZkKaDvv4AsekXRSyAp9KHm2oxmJvhNu-HCBgM7_3ca6T1ZSSCVled_jtKUExnoLNbxGnh39_5SwnOB2Q2FHaqjaV7E9ILdqFSzRhyZjQji/s400/GPN-2002-000114.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Goddard Space Flight Center Dedication Ceremony 1961</i></span></td></tr>
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After the Draper and Goett conversation, a meeting at <b><i><a href="https://en.wikipedia.org/wiki/Goddard_Space_Flight_Center" target="_blank">Goddard</a> </i></b>was held November 22, 1960, to discuss a six month $100,000 contract with the Instrumentation Laboratory for an Apollo study and preliminary design.<br />
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The details were proposed by Trageser at MIT and <b><i>Robert G. Chilton</i></b>, of the Space Task Group at Langley. A technical proposal was submitted on December 23, and the contract started in February.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUctjOoBcBnYst4TD1zGIaJ-akkWrKkPU-bkUvtSb8tYxo7kiWRTxN2Ci8O_jegzQehKXQ8QOMFyz_TpcX8O8lycJIWfQIWOG2C-Uuz31u35Vyl_7YvZw8vx60b9joBI4FvMe-8t5pCs7-/s1600/Robert+G+Chilton.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1058" data-original-width="832" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUctjOoBcBnYst4TD1zGIaJ-akkWrKkPU-bkUvtSb8tYxo7kiWRTxN2Ci8O_jegzQehKXQ8QOMFyz_TpcX8O8lycJIWfQIWOG2C-Uuz31u35Vyl_7YvZw8vx60b9joBI4FvMe-8t5pCs7-/s320/Robert+G+Chilton.png" width="251" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Robert G. Chilton</i></span></td></tr>
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Trageser and Chilton developed the basic configuration of the proposed trial design which prevailed throughout the program. They determined the system should consist of a general purpose digital computer, a space sextant, an inertial guidance unit (gyro stable platform with accelerometers), a control and display console for the astronauts, and supporting electronics.<br />
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The in flight autonomy of the earlier Air Force and NASA studies seemed appropriate to the manned mission, particularly since some urged that the mission should not be vulnerable to interference from hostile countries.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKPGPVFIjKaDLGshyphenhyphenKoICIrKk4jHoOKNje6ByiKvCa6pcUooVPOY-rNZPY-J1GlsX1hVaADkBzKeYscyW2tvKB268kOM-nmSMlENc5eF9NAYNmxftTWBLTRMg67XIZj4SnUbtqJ48tM2dQ/s1600/c003.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="405" data-original-width="592" height="272" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKPGPVFIjKaDLGshyphenhyphenKoICIrKk4jHoOKNje6ByiKvCa6pcUooVPOY-rNZPY-J1GlsX1hVaADkBzKeYscyW2tvKB268kOM-nmSMlENc5eF9NAYNmxftTWBLTRMg67XIZj4SnUbtqJ48tM2dQ/s400/c003.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Space Task Group Director Robert R. Gilruth, left, and Langley Research Director Floyd L. Thompson, center, welcome NASA Administrator T. Keith Glennan to Langley Field, Virginia, for a January 1961 tour.</i></span></td></tr>
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It was judged important to utilize the man in carrying out his complex mission rather than merely to bring him along for the ride. In addition, a certain value to self-contained capability was envisioned for future deep space programs for other reasons:<br />
<br />
<ol>
<li>First, the finite electromagnetic signal transmission time makes fast responding ground remote control impossible.</li>
<li>Second, it was envisioned that the country would eventually have many missions underway at the same time and it was important to avoid saturation of the large expensive ground stations .</li>
</ol>
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The initial Apollo contract at the Instrumentation Laboratory studied certain navigation measurements easily made by a human such as the timing of star occulations by the moon and earth during the circumlunar voyage.<br />
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Of significant importance, however, Battin devised a generalized <b><i>recursive navigation formulation</i></b> to incorporate each navigation measurement of any type as it was made, such as the star occulatation or a sextant measurement, so as to update and improve in an <b><i>optimum least squares</i></b> sense the estimate of spacecraft position and velocity. Several navigation measurement schemes were formulated as experiments in hopes that they could be studied and verified by the astronauts soon to fly in <a href="https://en.wikipedia.org/wiki/Project_Mercury" target="_blank"><b><i>Mercury</i></b></a>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2GTOiI9O73Ofle8bV1vR9cJbtG-K5hpKg2KRaPF9-51zkxaqnLFgs_0m5gGP9hMfIsT-qFf4QelZBEEyNVnTSsHrQNqAjugmTz3CVlvMqSoyh76AUElHibw-ubRnIBvYqPUQRIWolVio/s1600/c016.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="401" data-original-width="589" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_2GTOiI9O73Ofle8bV1vR9cJbtG-K5hpKg2KRaPF9-51zkxaqnLFgs_0m5gGP9hMfIsT-qFf4QelZBEEyNVnTSsHrQNqAjugmTz3CVlvMqSoyh76AUElHibw-ubRnIBvYqPUQRIWolVio/s400/c016.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Robert Gilruth (second from left), Director of the Space Task Group, and chief assistants <b>Charles Donlan</b> left), Maxime Faget, and Robert Piland in August 1960 discuss selection of contractors to study feasibility of a manned circumlunar mission.</i></span></td></tr>
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Organization of the various NASA centers on Apollo was underway in November 1960, in <b><i>Apollo Technical Liaison Groups</i></b> coordinated by <b><i>Charles J. Donlan</i></b> of the Space Task Group.<br />
<br />
<i><span style="color: #274e13;">[<b>Apollo Technical Liaison Groups </b>(1960):</span></i><br />
<br />
<ul>
<li><i><span style="color: #274e13;">Configurations and Aerodynamics,</span></i></li>
<li><i><span style="color: #274e13;">Guidance and Control,</span></i></li>
<li><i><span style="color: #274e13;">Group on Heating,</span></i></li>
<li><i><span style="color: #274e13;">Human Factors,</span></i></li>
<li><i><span style="color: #274e13;">Instrumentation and Communications,</span></i></li>
<li><i><span style="color: #274e13;">Mechanical Systems,</span></i></li>
<li><i><span style="color: #274e13;">On-board Propulsion,</span></i></li>
<li><i><span style="color: #274e13;">Structures and Materials and</span></i></li>
<li><i><span style="color: #274e13;">Trajectory Analysis]</span></i></li>
</ul>
<br />
The <b><i>Guidance and Control Technical Liaison Group</i></b> first met in January 1961 under <b><i>Richard Carley</i></b> of the Space Task Group. The contract then being negotiated with the MIT Instrumentation Laboratory in the guidance and control area was acknowledged as needed to augment the Convair, General Electric, and Martin feasibility studies.<br />
<br />
At the second meeting in April 1961, this group started work on the preparation of the guidance, navigation, and control specifications for the Apollo spacecraft.
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgouc2vjWfJ26PFX6myy9yMcXW36RgQQDktd4I0FpBGdTaCtlTJ9yd22Z26VQje3HWSCwswalrHzzERNED0-hvGIA8Ix9dFXJqqJRFAQUUbRM2KSpExF_uh3OO4F8685_bFKzoE0lyQ6YHj/s1600/John-F.-Kennedy-sailing.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1010" data-original-width="1600" height="251" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgouc2vjWfJ26PFX6myy9yMcXW36RgQQDktd4I0FpBGdTaCtlTJ9yd22Z26VQje3HWSCwswalrHzzERNED0-hvGIA8Ix9dFXJqqJRFAQUUbRM2KSpExF_uh3OO4F8685_bFKzoE0lyQ6YHj/s400/John-F.-Kennedy-sailing.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>John F. Kennedy sailing</i></span></td></tr>
</tbody></table>
<br />
The following month on May 25, 1961, <b><i>President Kennedy</i></b> in a special message to Congress urged the nation to <i>"commit itself to achieving the goal, before this decade is out, of landing a man on the moon..."
</i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLUSlrbxr5mInlED1JMGNBD66VmtbUvXbMtOFsakLCxtyhLncBtYtLLN-VMMBWF0YsroV5zynk9DIh-jYwdSSHByw_mphSSDTDrH3QpM768U_Ke_6-EPLTgfuYp09m9b8I5i0S4JB2uBy8/s1600/RalphRagan%2540300x300.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLUSlrbxr5mInlED1JMGNBD66VmtbUvXbMtOFsakLCxtyhLncBtYtLLN-VMMBWF0YsroV5zynk9DIh-jYwdSSHByw_mphSSDTDrH3QpM768U_Ke_6-EPLTgfuYp09m9b8I5i0S4JB2uBy8/s1600/RalphRagan%2540300x300.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Ralph Ragan, Deputy Director for NASA Programs, MIT Instrumentation Laboratory</i></span></td></tr>
</tbody></table>
<br />
With the impetus of the presidential challenge, the efforts at the Instrumentation Laboratory changed character. The role the Laboratory would play depended not only on its earlier space studies but also the fact that another team was in place at the Laboratory, which had just accomplished a similar task to develop the <b><i>Navy's <a href="https://en.wikipedia.org/wiki/UGM-27_Polaris" target="_blank">Polaris missile</a></i></b> guidance system on an extremely tight schedule.<br />
<br />
<b><i>Ralph Ragan</i></b>, who led that Polaris effort, immediately joined with Trageser, to work with Chilton to define an <b><i>Apollo guidance, navigation, and control system</i></b> to support a flight test as early as 1963.
<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjOC7MY-Af_6YmA6z2H6xYjR0e4VpKmsKzV2Txkry-KeUGZc-esL6fJjDkLt_pqAkuXke3HqX1M3RSs4GRgzDryWucb03zJHHV5yrP7CLrourqAO80OTWlKEW_5UeVisDPJUjX4DqjpnET/s1600/PGNCS_1966_X.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="852" data-original-width="1234" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjOC7MY-Af_6YmA6z2H6xYjR0e4VpKmsKzV2Txkry-KeUGZc-esL6fJjDkLt_pqAkuXke3HqX1M3RSs4GRgzDryWucb03zJHHV5yrP7CLrourqAO80OTWlKEW_5UeVisDPJUjX4DqjpnET/s400/PGNCS_1966_X.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Lunar Module's primary guidance, navigation, and control system's block diagram (final version seen more or less from MIT's perspective). Command Module had a similar system. Additionally the spacecrafts were guided, navigated, and tracked from ground using transponders, telemetry and up-links. This block diagram includes most input devices but is missing output devices such as control electronics (CES - Control Electronics System), rockets (MPS - Main Propulsion System), attitude jets (RCS - Reaction Control System), etc. But this shows at least the primary nucleus of the system, the LGC or AGC guidance computers.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #4c1130;">[In the above diagram we have the following block names.</span></i><br />
<ul>
<li><i><span style="color: #4c1130;">AOT - Alignment Optical Telescope</span></i></li>
<li><i><span style="color: #4c1130;">LR - Landing Radar</span></i></li>
<li><i><span style="color: #4c1130;">RR - Rendezvous Radar</span></i></li>
<li><i><span style="color: #4c1130;">CDU - Coupling Data Unit</span></i></li>
<li><i><span style="color: #4c1130;">DSKY - (AGC) Display and Keyboard</span></i></li>
<li><i><span style="color: #4c1130;">LGC - LM Guidance Computer (or AGC)</span></i></li>
<li><i><span style="color: #4c1130;">PTA - Pulse Torque Assembly</span></i></li>
<li><i><span style="color: #4c1130;">IMU - Inertial Measurement Unit</span></i></li>
<li><i><span style="color: #4c1130;">PSA - Power Servo Assembly</span></i></li>
<li><i><span style="color: #4c1130;">OSS - Optical Subsystem</span></i></li>
<li><i><span style="color: #4c1130;">ISS - Inertial Subsystem</span></i></li>
<li><i><span style="color: #4c1130;">RS - Radar Subsystem</span></i></li>
<li><i><span style="color: #4c1130;">CSS - Computer Subsystem</span></i></li>
</ul>
<i><span style="color: #4c1130;">All together LM had 12 subsystems (see <a href="https://dodlithr.blogspot.fi/2012/07/lunar-module-control-subsystems-part-8.html">here</a> for additional details)]</span></i><br />
<br />
By July 1961, a task statement had been written and on August 10, by letter, NASA contracted the Laboratory for the first year's development of the <b><i><u>Apollo guidance and navigation system</u></i></b>. This was the first major Apollo contract awarded by NASA. The early start was justified by the central role this function would necessarily have.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsb_Gq2vfX-vmnvZ1D-P2FcbnsR0WtpuoVQKeJ6Vgxwarsn6PKk51p1HyGBGfvRFhq51LWYvn-p9fzKAfLD1aXJBlA6eit2y2r04KE9zrzqdcL7QL3j1qcsPhJ0df_434ZUkWvs-SRA-1B/s1600/DaveHoag%2540300x300.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsb_Gq2vfX-vmnvZ1D-P2FcbnsR0WtpuoVQKeJ6Vgxwarsn6PKk51p1HyGBGfvRFhq51LWYvn-p9fzKAfLD1aXJBlA6eit2y2r04KE9zrzqdcL7QL3j1qcsPhJ0df_434ZUkWvs-SRA-1B/s1600/DaveHoag%2540300x300.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><i style="color: #cc0000; font-size: medium;">The writer of this history, David Garrett Hoag</i></td></tr>
</tbody></table>
<br />
Key personnel from the Laboratory's Polaris Team joined Trageser who was named by Dr. Draper as Director of Project Apollo. Ragan became Operations Director, and <b><i>David Hoag (the writer of this text)</i></b>, having been Technical Director of Polaris became Technical Director of Apollo.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEk4vtsUk7_phMv8f4WeaExM_QTeEhgfXjNdSrmWBM619djpe9nQmU4C6UtyLU05RBV-VVduq8juW-gh4rMICbf7pGTdLMAJeLWbPo37pOw1ZqxTfzJneCBCoBE5HzKhixxZSd5w8PnWlV/s1600/polaris-missile.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1261" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEk4vtsUk7_phMv8f4WeaExM_QTeEhgfXjNdSrmWBM619djpe9nQmU4C6UtyLU05RBV-VVduq8juW-gh4rMICbf7pGTdLMAJeLWbPo37pOw1ZqxTfzJneCBCoBE5HzKhixxZSd5w8PnWlV/s400/polaris-missile.jpg" width="315" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Polaris missile</i></span></td></tr>
</tbody></table>
<br />
That same August 1961, <a href="https://en.wikipedia.org/wiki/James_E._Webb" target="_blank"><b><i>James Webb</i></b></a>, NASA Administrator, invited Dr. Draper and members of the Instrumentation Laboratory Apollo Team to Washington for discussions.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjplvbAyBPcs0ifYTpU9bqp6D5y_emmiTHle_ePT0F1SCskWC_v8Pb2RLNAB5ZSOEWssi9P3m6wHsnFG2bX4VZDJQG5yupu7N9y0x9hWJ-YgxjYAQJTUSf1PDaLu8sCOdIAgeZIsrYtSKtY/s1600/Truman_and_Webb_at_NASA_Headquarters_-_GPN-2000-001682.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1024" data-original-width="810" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjplvbAyBPcs0ifYTpU9bqp6D5y_emmiTHle_ePT0F1SCskWC_v8Pb2RLNAB5ZSOEWssi9P3m6wHsnFG2bX4VZDJQG5yupu7N9y0x9hWJ-YgxjYAQJTUSf1PDaLu8sCOdIAgeZIsrYtSKtY/s400/Truman_and_Webb_at_NASA_Headquarters_-_GPN-2000-001682.jpg" width="316" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>About two months later on November 3, 1961 the former President Harry S. Truman (left) visited also the newly opened NASA Headquarters. Here he is walking with James E. Webb.</i></span></td></tr>
</tbody></table>
<br />
The meeting took place on the 31st at NASA Headquarters and continued at Webb's house for dinner that evening. In acknowledging the difficulty of guiding the lunar mission, two things concerned Webb,<br />
<br />
<ol>
<li>first he wanted to know when the guidance system could be ready. Draper provided the accurate forecast: <i><span style="color: #20124d;"><b>"You'll have it when you need it". </b></span></i></li>
<li>Second, he wanted assurances that the equipment would really work. In reply, Draper volunteered to make the first flight and run the system himself.</li>
</ol>
<br />
Hardly anyone doubted Draper's sincerity and in letters to NASA officials he repeatedly reminded them of his long experience of over 30 years in instrumentation design, as a pilot, and as a flight engineer. It was Draper's contention that although he himself was both a pilot and an engineer, it would be easier to train an engineer to be a pilot than to train a pilot in the necessary engineering.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpYwD5UsqsatfV_hKlP4dCAFa7I4TMQo4vSI1rYgkc6EWC0syruM9xhRFL1Hbrqwq7yGTD8rOqQLBJYJDyTjHOqnm2DBAAfWpyDY5lhFE-WONRGvZw3pwntAuIW18D-QxkTg22iivjM6Ly/s1600/AGC_1963.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="599" data-original-width="771" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpYwD5UsqsatfV_hKlP4dCAFa7I4TMQo4vSI1rYgkc6EWC0syruM9xhRFL1Hbrqwq7yGTD8rOqQLBJYJDyTjHOqnm2DBAAfWpyDY5lhFE-WONRGvZw3pwntAuIW18D-QxkTg22iivjM6Ly/s400/AGC_1963.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>1963 version of the Apollo Guidance Computer plan</i></span></td></tr>
</tbody></table>
<br />
The early conceptual work on the guidance and navigation proceeded rapidly. Trageser, Chilton, and Battin had worked out the overall configuration which was to hold to the end. The many maneuvers both in orientation and in translation would require a full <b><i>three axis inertial measurement unit</i></b> with gyros and accelerometers.<br />
<br />
An <b><i>optical system</i></b> would be needed to align the inertial system periodically to the stars. The optical system was also necessary to make navigation measurements in a sextant configuration by observing the direction of the earth and moon against the background stars.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRtAHoZalmiknLGMdl0rhM_fGjCCVDdQsb6fFdW-zOFgxDNulnJKTDIh75ECWYzHOEdRVWVh4WoLHDdWLafncl4X08xIFs4XqGuL-DJH7nR6NbemR5xVqRiACBD1HIammkwFS-iQAwijHi/s1600/maxresdefault+%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="720" data-original-width="1280" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRtAHoZalmiknLGMdl0rhM_fGjCCVDdQsb6fFdW-zOFgxDNulnJKTDIh75ECWYzHOEdRVWVh4WoLHDdWLafncl4X08xIFs4XqGuL-DJH7nR6NbemR5xVqRiACBD1HIammkwFS-iQAwijHi/s400/maxresdefault+%25281%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Univac 490 computer during 1960's. Before Apollo (and missile) on-board small computers the normal and acceptable computer was something of the size of a large room. This was before microprocessors in 1970's and the small desktop computers later in 1980's. Large computers were used (usually IBM) to emulate the AGC (Apollo Guidance Computer) before it was actually made and ready to be used in testing and simulations. In the mission control NASA used Univac 494, 1232 and 642B models, IBM 360/75J amd 3C [Computer Control Company] / Honeywell DDP-224 computer models (1968).</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">[The following video shows some of those computers used by Apollo Mission, many of which were busy doing communications (in many remote sites around the World), simulations or similar less obvious activities. Nowadays all those computers could be replaced by microprocessors, much smaller in size. Maybe 30-50 such computers operated the whole active mission segment during flights in a very primitive networks using very miscellaneous programs, languages, connections, hardware, etc. Nowadays using a single efficient processor with a single consistent programming interface would help to speed up the development effort considerably]</span></i><br />
<br />
<i><span style="color: #274e13;">YouTube video:</span></i> <a href="https://youtu.be/nsy2QAboRzE" target="_blank"><b><i>"Sperry Rand Univac NASA Apollo Computer History, 1230, 490, 494, NASCOM Tracking, IBM, Australia"</i></b></a><br />
<br />
A <b><i>general purpose digital computer</i></b> was required to handle all the data. And an arrangement of display and controls for the astronaut to operate the system would be needed. Considerable extension of navigation and guidance theory, trajectory analysis, phenomenological and human limitations to visual sightings of celestial objects, electronic packaging options, materials characteristics, reliability and quality assurance procedures, and management methods all were identified for early study.
<br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">YouTube video</span></i>: <a href="https://youtu.be/YIBhPsyYCiM" target="_blank"><b><i>"Computer for Apollo"</i></b></a><br />
<br />
It was recognized from the start that the Instrumentation Laboratory would utilize industrial support contractors to augment its engineering team and to produce the designs coming from the engineers. This followed the successful pattern utilized in the development of the Polaris missile guidance system.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8ulVLF9HgdwA8BuWrljIwqnLCIwLiX7uXAodvYMOeNyi7yRk4kh9rcpF1g1e0zBylnhvXS9pJhIk3OMaW3lqRPMLK-vF6w4o0ezGP38ULWQ_Q133sDQVjNfLtosTsIisaEx03fKW8OiCV/s1600/c095b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="412" data-original-width="581" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8ulVLF9HgdwA8BuWrljIwqnLCIwLiX7uXAodvYMOeNyi7yRk4kh9rcpF1g1e0zBylnhvXS9pJhIk3OMaW3lqRPMLK-vF6w4o0ezGP38ULWQ_Q133sDQVjNfLtosTsIisaEx03fKW8OiCV/s400/c095b.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The cabin section (or primary structure) of the CM is assembled at North American in 1965.</i></span></td></tr>
</tbody></table>
<br />
Meanwhile, NASA started the procurement process for the <b><i>Spacecraft Principal Contractor</i></b>. The request for proposal was issued on July 28, 1961. <a href="https://en.wikipedia.org/wiki/North_American_Aviation" target="_blank"><b><i>North American Aviation</i></b></a> was selected on November 29 for the Apollo Command Module, Service Module, and boost vehicle adapter. Their contract excluded the guidance and navigation which was to be government furnished by the Industrial Support contractors of the Instrumentation Laboratory.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2IEesplhbDyDlnVrApxF4byTzeSu8SmfAXMhUcUL04fDXa64iXpubLB44t-wob_-mYtGWd1P1EjV95ty6o7EuzHq9q6d7ArtUfX30jZmc7RFDb5sKVHDSoIHlZI1FhDqn2zyGOaZsSez2/s1600/c090a.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="406" data-original-width="534" height="302" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2IEesplhbDyDlnVrApxF4byTzeSu8SmfAXMhUcUL04fDXa64iXpubLB44t-wob_-mYtGWd1P1EjV95ty6o7EuzHq9q6d7ArtUfX30jZmc7RFDb5sKVHDSoIHlZI1FhDqn2zyGOaZsSez2/s400/c090a.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The North American Aviation plant at Downey, California, developed and produced the Apollo command module.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">YouTube video:</span></i><b><i> <a href="https://youtu.be/0kpNkEdB1o0" target="_blank">"The North American Aviation Story, 1950's Film"</a></i></b><br />
<br />
In early 1962 briefings to industry were made for the industrial support to the Instrumentation Laboratory for the guidance and navigation systems. Twenty-one bidders responded and three awards were made on May 8.<br />
<br />
<a href="https://en.wikipedia.org/wiki/ACDelco#AC_Spark_Plug_Division" target="_blank"><b><i>A.C. Spark Plug Division, of General Motors</i></b></a>, was given responsibility for the production of the inertial system, ground support equipment, and systems integration assembly, and test.<br />
<br />
<a href="https://en.wikipedia.org/wiki/Paul_Kollsman" target="_blank"><b><i>Kollsman Instrument Corporation</i></b></a> was the industrial support for the optical subsystems, and <a href="https://en.wikipedia.org/wiki/Raytheon" target="_blank"><b><i>Raytheon</i></b> </a>for the computer.<br />
<br />
Earlier, A.C. Spark Plug Division had been selected for the gyro production and <a href="https://en.wikipedia.org/wiki/Sperry_Corporation" target="_blank"><b><i>Sperry</i></b></a> for the accelerometer production, both to the Instrumentation Laboratory designs for these inertial systems components.
<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmsiiiOP3jrlmt_0s_gNo_se_upXZG7BuJY0Unw4cQEiEED0nOtsQW7zehSgFij6_1VTdQEpYj5HvYWWXi8ArHdYBMjsE7mpqOn0kBU84Ih6awwyTjgP1hw-2rnCrf2r9G9GcWCtG2sfqe/s1600/Kollsman+Instrument+Corp+optical+department+building_.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="550" data-original-width="685" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmsiiiOP3jrlmt_0s_gNo_se_upXZG7BuJY0Unw4cQEiEED0nOtsQW7zehSgFij6_1VTdQEpYj5HvYWWXi8ArHdYBMjsE7mpqOn0kBU84Ih6awwyTjgP1hw-2rnCrf2r9G9GcWCtG2sfqe/s400/Kollsman+Instrument+Corp+optical+department+building_.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i><span style="font-size: 12.8px;"><span style="color: #cc0000; font-size: x-small;">Kollsman Instruments Co. building. </span></span><span style="color: #cc0000; font-size: x-small;">In 1928 <a href="https://en.wikipedia.org/wiki/Paul_Kollsman" target="_blank">Paul Kollsman</a> founded his company with just $500 o</span>f seed money.</i></span></td></tr>
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During this early 1962 period, the mission and its hardware were being further defined by NASA, North American Aviation, and the Instrumentation Laboratory. The Space Task Group had evolved into the <b><i><a href="https://en.wikipedia.org/wiki/Johnson_Space_Center" target="_blank">Manned Spacecraft Center</a></i></b> the previous October, and the selection of the Houston, Texas, site for the new center had been made.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrzKiGdia6HHSAERCRKqjJumKk1xYhoGWBo1EeIE4IfvrxeFbrjQDE4E9g0bc5FmVtuX0xd-FGaFLgdfLyrvC1DBQxsIPSgWhv28NAbsocHUV4XdK0-AR0_fFVPEW-QWXWRANBtrS80SV-/s1600/Aerial_View_of_the_Johnson_Space_Center_-_GPN-2000-001112.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1600" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrzKiGdia6HHSAERCRKqjJumKk1xYhoGWBo1EeIE4IfvrxeFbrjQDE4E9g0bc5FmVtuX0xd-FGaFLgdfLyrvC1DBQxsIPSgWhv28NAbsocHUV4XdK0-AR0_fFVPEW-QWXWRANBtrS80SV-/s400/Aerial_View_of_the_Johnson_Space_Center_-_GPN-2000-001112.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Manned Spacecraft Center, Houston, Texas, currently Johnson Space Center</i></span></td></tr>
</tbody></table>
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The <b><i>Apollo Spacecraft Program Office</i></b> was formed and managed by <b><i>Charles Frick</i></b> and <b><i>Robert Piland</i></b>. But a great controversy was underway, which had strong implications on the whole design process.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhElg__DM5oQwZA5gi1Y0ezrFqZb-RQs23HplXgNTH7NMQ-7YYzzN_JSDjTVK8MWJeIB7dVXdomHhXKCiMVoeTDcHi5inHs2lslNvJwIISliIG-soLITTZtJL9N3shWGucRFKjhKidFXZpH/s1600/Joe_Shea.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="640" data-original-width="437" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhElg__DM5oQwZA5gi1Y0ezrFqZb-RQs23HplXgNTH7NMQ-7YYzzN_JSDjTVK8MWJeIB7dVXdomHhXKCiMVoeTDcHi5inHs2lslNvJwIISliIG-soLITTZtJL9N3shWGucRFKjhKidFXZpH/s400/Joe_Shea.jpg" width="272" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Dr. Joseph H. Shea, Program Manager, Apollo Spacecraft Program Office, NASA Manned Spacecraft Center</i></span></td></tr>
</tbody></table>
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<i><span style="color: #274e13;">Audio mp3 file</span></i>:<b><i> <a href="http://www.workingonthemoon.com/ALLMS/Audio/Opening_Remarks_Shea.mp3" target="_blank">"Dr. Joseph H. Shea's talk, 24 mins 52 secs, at the 1966 Apollo Lunar Landing Symposium"</a></i></b> - <i><span style="color: #20124d;">(notice! there are some tape speed problems in this audio..)</span></i><br />
<div>
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The existing mission plan included two large Saturn booster launches from earth, with an orbital rendezvous to assemble in earth orbit a large spacecraft for the lunar trip. This spacecraft would then be injected to tile moon and would in its entirety land the three astronauts in the command module on the lunar surface using the propulsion of a large lunar landing stage.<br />
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The guidance and navigation of this maneuver being studied at MIT incorporated a large periscope-range-finder so that an astronaut could view the lunar surface during maneuvers as he landed in the awkward position 25 meters up on top of the stacked spacecraft. The lunar landing stage would be left on the surface for the return; the Command Module being lifted on the ascent and return by the Service Module propulsion.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFbrMW_TAO5y3lAB9ef5HZTCcFnJxm3yzuExGIz9dC21VGAkxEJKzgidsQNcDurIj6eK_9uzOAirvpUrdwIdnXoy0pmVCE-HbAh-UgtQkibm0oq9UZn3UqBbXEQFWFAqesAIXQvtq7ghQx/s1600/6127141060_098c773e37_z.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="640" data-original-width="487" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFbrMW_TAO5y3lAB9ef5HZTCcFnJxm3yzuExGIz9dC21VGAkxEJKzgidsQNcDurIj6eK_9uzOAirvpUrdwIdnXoy0pmVCE-HbAh-UgtQkibm0oq9UZn3UqBbXEQFWFAqesAIXQvtq7ghQx/s400/6127141060_098c773e37_z.jpg" width="303" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>LOR - Lunar Orbit Rendezvous idea showing early LEM (LM) model</i></span></td></tr>
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The alternate mission configuration, called <a href="https://en.wikipedia.org/wiki/Lunar_orbit_rendezvous" target="_blank"><b><i>Lunar Orbit Rendezvous</i></b></a>, had been discussed for some time, particularly by <a href="https://en.wikipedia.org/wiki/John_Houbolt" target="_blank"><b><i>John Houbolt</i></b></a> and his colleagues at Langley. In this case, a single Saturn launch would inject a smaller spacecraft assembly towards the moon which included a relatively small Lunar Excursion Module for the actual landing, leaving the Command and Service Modules in lunar orbit.<br />
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The return, of course, required a rendezvous in lunar orbit, which was considered by the critics of this scheme as particularly difficult and dangerous.
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<i><span style="color: #274e13;">YouTube video:</span></i> <a href="https://www.youtube.com/watch?v=ikYHsXF_k0Q" target="_blank"><b><i>"Landing on the Moon" Thomas Kelly (GRUMMAN Chief Engineer) explains how the lunar module works.</i></b></a><br />
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Finally in <b>June 1962</b>, the decision was made by NASA in favor of the lunar orbit rendezvous mission with its real advantages in weight and expense.<br />
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The procurement process for the Lunar Landing Module was initiated in July and on November 7 <a href="https://en.wikipedia.org/wiki/Grumman" target="_blank"><b><i>Grumman Aircraft Engineering Corporation</i></b></a> was chosen to design and build the Lunar Excursion Module.<br />
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<i><span style="color: #274e13;">YouTube video:</span></i> <a href="https://youtu.be/jOUsMoWfSZI" target="_blank"><b><i>"Moon Machines: APOLLO / Lunar Module, Grumman Corporation history"</i></b></a><br />
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With this, the Instrumentation Laboratory and the industrial support contractor tasks were expanded to include the guidance and navigation for the Lunar Module.<br />
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Two additional guidance and navigation sensors would be required, however, which were assigned to Grumman. They were<br />
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<ol>
<li>the <b><i>landing radar (LR)</i></b>, measuring the altitude and velocity of the Lunar Module with respect to the lunar surface, and</li>
<li>the <b><i>rendezvous radar (RR)</i></b> to track a transponder on the Command Service Module to provide relative direction and range.</li>
</ol>
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Specifications for these radars were written by the Instrumentation Laboratory since the signals were to be used by the guidance and navigation computer in the Lunar Module (LM).<br />
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It had been decided somewhat earlier that the first flight test, being scheduled for earth orbit exercises starting in the fall of 1963, and soon to be rescheduled to 1965, could not be met with a full guidance and navigation design capable of a lunar landing mission. For this reason, a <b><i>Block I</i></b> design was identified for the guidance and navigation equipment to support the first earth orbital flights. A <b><i>Block II</i></b> design was to follow for the later lunar flights.
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With the engineering help of the industrial support contractors, the Instrumentation Laboratory started design releases of production drawings for manufacture in July 1962, using a <b><i>formal design review, release, and revision procedure</i></b> which was followed throughout the program. (The last design release numbered 38,86;8: was made in 1975 to provide the erasable memory load for the guidance and navigation computer in the last Command Module used to rendezvous with the Soviet Cosmonauts in the Apollo-Soyuz mission.)"
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<b><span style="color: #0c343d;">Hardware Design /10/
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"The decisions that were being made early and rapidly for the guidance and navigation system were to have a lasting impact on the Apollo Program from the point of view of <b><i>mission design</i></b>.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGP75PtrHL-OjOaQJaNCYKudxV1KJnboobXyBevuQ9jE8J8P6CPIqavwQgZD3I3sy-R6KWcB-3WSyL-ft4RsVM5Y9Lz1KWZSI-c-ha9mKl03ouXIVRG1ds9z4v0FqZJPMbhR6b5_rVZb1s/s1600/IMU__.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="485" data-original-width="625" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGP75PtrHL-OjOaQJaNCYKudxV1KJnboobXyBevuQ9jE8J8P6CPIqavwQgZD3I3sy-R6KWcB-3WSyL-ft4RsVM5Y9Lz1KWZSI-c-ha9mKl03ouXIVRG1ds9z4v0FqZJPMbhR6b5_rVZb1s/s400/IMU__.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo 3-axis IMU, same hardware was used for CM and LM.</i></span></td></tr>
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The <b><i>inertial measurement unit (MU)</i></b> borrowed its technology heavily from the Polaris missile guidance experience at the Laboratory.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibumTqGJvqZcMaj0vgXd6FuOrQT31P7vL8lQkqXg3s3p1FezrF2cxrayrpt2oDlrI7Iq7qdfjJWMI_txl88_H0NUtWNFtnBn-iVFaQc0ZoBmnYk7Wqn4IVB7ViZenW5luNUmvc_GXkat_7/s1600/John_Miller_2002.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="433" data-original-width="485" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibumTqGJvqZcMaj0vgXd6FuOrQT31P7vL8lQkqXg3s3p1FezrF2cxrayrpt2oDlrI7Iq7qdfjJWMI_txl88_H0NUtWNFtnBn-iVFaQc0ZoBmnYk7Wqn4IVB7ViZenW5luNUmvc_GXkat_7/s400/John_Miller_2002.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>John Miller, 2002 at the <a href="https://authors.library.caltech.edu/5456/1/hrst.mit.edu/hrs/apollo/public/conference4/miller.htm" target="_blank">AGC Conference</a></i></span></td></tr>
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<b><i>John Miller</i></b> assembled a Laboratory team and was supported by A.C. Spark Plug in the inertial system design. The mechanical design was undertaken by <b><i>John Nugent</i></b>, who had done that work for Polaris.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijmnDbThlBZ59Olv5sQDxTapriMUfobZ2xGPMlziZW5jO6s0jhPC00Hma3Vhfm6whLO7dG7l2OYtQTmqafLLOFh_inqFGPsgUDu9VID2QvgejMUxf6Pw7Tjad_IwvB9TAGAmWbKnUxWKG1/s1600/John_Nugent_1218-1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1257" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijmnDbThlBZ59Olv5sQDxTapriMUfobZ2xGPMlziZW5jO6s0jhPC00Hma3Vhfm6whLO7dG7l2OYtQTmqafLLOFh_inqFGPsgUDu9VID2QvgejMUxf6Pw7Tjad_IwvB9TAGAmWbKnUxWKG1/s400/John_Nugent_1218-1.jpg" width="313" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>John Nugent at the Gemini 1218 computer with Barbara King at the keyboard.</i></span></td></tr>
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In order to simplify the design considerably and to achieve more accuracy in the alignment to the stars, the inertial measurement unit was provided with only <b><i>three degrees of freedom</i></b> in its gimbals, although four gimbals would have permitted unlimited all-attitude freedom, With the natural choices for aligning the system for flight,only some unusual attitudes of the spacecraft would put the gimbals into lock where the alignment would be lost. The resulting constraint in <u><i>the design irritated the astronauts, although</i></u>, in retrospect, they had no particular trouble with the attitude limitations during missions.
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It was the stellar alignment of the inertial measurement unit which made this design significantly different from that of the Polaris system which was erected with gravity and gyrocompass action.<br />
The Apollo unit needed precision angle readout to the computer for each gimbal angle which would be compared with <b><i>star sighting angles</i></b>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrceG-YTxHUVSFnanaq5w8k9VxDzVTb5mhUTstm2Y133ESvNqRfMavMZEKSoPeFYdiQ_rY0DAwewp8n-IixOuoRJlPEBElhxsswkysq9fy9PfrbvK_jkIbXpC16deua8E8PW711vG3qOcq/s1600/Gilmore%252C+Jerold+P__.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="245" data-original-width="163" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhrceG-YTxHUVSFnanaq5w8k9VxDzVTb5mhUTstm2Y133ESvNqRfMavMZEKSoPeFYdiQ_rY0DAwewp8n-IixOuoRJlPEBElhxsswkysq9fy9PfrbvK_jkIbXpC16deua8E8PW711vG3qOcq/s400/Gilmore%252C+Jerold+P__.jpg" width="266" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Jerold P. Gilmore spent the majority of his career at the MIT Instrumentation Laboratory, later known as Charles Stark Draper Laboratory.</i></span></td></tr>
</tbody></table>
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The design of the inertial and optical angle interfaces to the computer was undertaken by <b><i>Jerold Gilmore.</i></b><br />
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<i><span style="color: #274e13;">[CDU - Coupling Data Unit</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">CDU was an additional device to hold the A/D and D/A converters for the AGC. Various methods was used to transmit different analog signals and to "couple" them to the computer. Since those days (before integrated circuits) you had to build those devices out of various semicnductor components. Apollo CDU used counters to convert signals.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhF0yWFtI6JVfi9PW1IZe1MmylePgHd4cfdstagx1dAzlMoxo5iuHvNEWvfPeHhCsuQLLT3xfuABFnCvXuIRXwSOFAQp7o067-li1hojsmDZi_ZRh5b73sa1kp_fSmQAC1vklhA2su7_xcP/s1600/CM_CDU.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="865" data-original-width="971" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhF0yWFtI6JVfi9PW1IZe1MmylePgHd4cfdstagx1dAzlMoxo5iuHvNEWvfPeHhCsuQLLT3xfuABFnCvXuIRXwSOFAQp7o067-li1hojsmDZi_ZRh5b73sa1kp_fSmQAC1vklhA2su7_xcP/s400/CM_CDU.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Command Module CDU, 12 x 22 x 6 inch size.</i></span></td></tr>
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<i><span style="color: #274e13;">Often the signals were not just converted to digital and red from the input channels but rather they were converted using various read/write and timing operations. But what ever methods were used the final product usually was some kind of binary number corresponding the analog value somewhere in the computers memory.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Both LM and CM had one CDU located close to the AGC. A typical CM CDU had 5 CDU channels 3 for the ISS and 2 for the optics (OSS). Each channel had one input and output.]</span></i><br />
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The equipment, called the <b><i>coupling data unit (CDU)</i></b>, included a complex arrangement of system operational modes among the inertial, optical, and computer hardware.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7fmZ1id9ljL5Pt614BtlM9bG9jFHt0qxqwMlnOVCcAf-aUU41ygdciWiCxV1D6EaZIJAm_ANQNM_XTcZcA5lJS8zkduRrMctX6n1snE_osZAYE9Y_AjP7xx4iP1PUio8O1b0VeBCGzu8g/s1600/IMU_OSS.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="553" data-original-width="625" height="353" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7fmZ1id9ljL5Pt614BtlM9bG9jFHt0qxqwMlnOVCcAf-aUU41ygdciWiCxV1D6EaZIJAm_ANQNM_XTcZcA5lJS8zkduRrMctX6n1snE_osZAYE9Y_AjP7xx4iP1PUio8O1b0VeBCGzu8g/s400/IMU_OSS.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>The OSS and ISS were rigidly connected together using the navigation base. Any movement between them would have created navigation error.</i></span></td></tr>
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As the <b><i>inertial system (ISS)</i></b> design developed, it came under attack as not having sufficient inherent or proven reliability to support Apollo in spite of considerable attention to this important issue. If a single gyro wheel stopped running or if a single gyro developed excessive drift instability, the mission could fail and the astronauts be endangered. Many design, test, and operational techniques evolved and were utilized to achieve the final record: over 2500 hours in flight operations of the inertial measurement unit supporting all Apollo missions (over 7500 gyro unit hours) without any failures.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb45EFnZHribOkdGMLXmF1skYe9WIaLqCyE-xdrvFWPUVtcRGgPPiWDLf0-pRpT0mBPjd8qzc8STKXQx61v6KjyEKeGw0pKJHkprT9SCsgCWMSgt8ajm48hvIItakLwtqk3Qq4zrqlmLwL/s1600/CM_Optics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="690" data-original-width="977" height="281" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhb45EFnZHribOkdGMLXmF1skYe9WIaLqCyE-xdrvFWPUVtcRGgPPiWDLf0-pRpT0mBPjd8qzc8STKXQx61v6KjyEKeGw0pKJHkprT9SCsgCWMSgt8ajm48hvIItakLwtqk3Qq4zrqlmLwL/s400/CM_Optics.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Command Module optics: Telescope and sextant side by side. Sextant's LOS penetrated the spacecraft hull to the landmark. Star was superimposed on it using a tilting mirror.</i></span></td></tr>
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<b><i>Philip Bowditch</i></b>, <b><i>Alex Koso</i></b>, and others at MIT, along with engineering support from Kollsman, undertook the design of the <b><i>optical system (OSS)</i></b>. Bowditch examined a number of configurations before a satisfactory sextant design was achieved.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjja7iXD4dKJtzyeXZtLaa3bsslmrxeI-eBcwWUfq9no4Q_JT74skZKUoGl_zp01OTyZ9QzXVWsJ1UXJ6tQ0BhCX-_kZuPFJmQ_19lHVcOoPgu7dVzqf5jZRl67EGbfNLnUAZXj9jK3_Ipe/s1600/CM_Optics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="704" data-original-width="991" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjja7iXD4dKJtzyeXZtLaa3bsslmrxeI-eBcwWUfq9no4Q_JT74skZKUoGl_zp01OTyZ9QzXVWsJ1UXJ6tQ0BhCX-_kZuPFJmQ_19lHVcOoPgu7dVzqf5jZRl67EGbfNLnUAZXj9jK3_Ipe/s400/CM_Optics.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Command module optics system</i></span></td></tr>
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The instrument was configured with one of its <b><i>lines-of-sight (LOS)</i></b> fixed along the axis of penetration of the spacecraft hull. This line was associated with the earth or moon side of the navigation angle. The other line-of-sight associated with the reference star was split from the first and tipped away by an articulating mirror in such a fashion that the navigation angle could be measured in any plane.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpHoC7JktbHV2ZXkVRDrHK9XMhDSdoDJYmDsklpEovhhxekh3cCo9OzoON1_7CL6Ot8yjMyYDXgCEwofKUMcTM-gHmdvwuVqsUmkSOErKJdq3diGPVyCKuaCkVYU52Sw2pEphIA5VD9yO3/s1600/Apollo_9_CM_Telescope_and_Sextant.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="788" data-original-width="779" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpHoC7JktbHV2ZXkVRDrHK9XMhDSdoDJYmDsklpEovhhxekh3cCo9OzoON1_7CL6Ot8yjMyYDXgCEwofKUMcTM-gHmdvwuVqsUmkSOErKJdq3diGPVyCKuaCkVYU52Sw2pEphIA5VD9yO3/s400/Apollo_9_CM_Telescope_and_Sextant.png" width="395" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo 9 CM Telescope and Sextant as seen from outside.</i></span></td></tr>
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The <b><i>angle of tilt</i></b> of the mirror, in conventional sextant fashion, was the desired measurement and was encoded for use by the computer navigation algorithms. The astronauts task was to control the orientation of the spacecraft so that the earth or moon was satisfactorily in the field of view, and then adjust the mirror and the measurement plane to get star image superimposed in his view on the selected earth or moon feature.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq64NCP7Fg9C8LHl2HMYLJabFeyxGLxkXcVLbX6JtTBvUx_ckZLfAklCtUh9AP6U-9HfR1M3T3EdgdLCubanayLV4NGA9jqZHykQUrIUW5a1r9vGanYme8QsS4TfA3UBYI0vE6eWzPMJCY/s1600/Midcourse_Navigational_Measurement.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="700" data-original-width="800" height="350" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq64NCP7Fg9C8LHl2HMYLJabFeyxGLxkXcVLbX6JtTBvUx_ckZLfAklCtUh9AP6U-9HfR1M3T3EdgdLCubanayLV4NGA9jqZHykQUrIUW5a1r9vGanYme8QsS4TfA3UBYI0vE6eWzPMJCY/s400/Midcourse_Navigational_Measurement.png" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Typical CM sextant measurement procedure: a) The astronauts task was to control the orientation of the spacecraft so that the earth or moon was satisfactorily in the field of view of the telescope. b) Then adjust the mirror and the measurement plane to get the star image superimposed in his view on the selected earth or moon feature.</i></span></td></tr>
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In order to achieve the necessary 10 arc second accuracy of this measurement, the sextant was provided with a 28 power eyepiece. However the field of view was thereby so severely limited that a second independent, articulating instrument at unity power and wide field called a scanning telescope was provided which could serve as a finder for the sextant and to which its direction could be slaved.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq2JvmnvA9PJXcmHjWhyphenhyphenUgUh8Rt7KLw766oWaepHdtvDAvKhQr4NRFvR3eb_cfaB0E6HvH8fpfp8GhchgnXfAbSsBndLpF_4oqyrvcTRXdq_EGIzMe1Gt4ufPclbmz4R9jkZVneEowqvCs/s1600/Apollo_CM_Sextant_Princible.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="824" data-original-width="1359" height="242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiq2JvmnvA9PJXcmHjWhyphenhyphenUgUh8Rt7KLw766oWaepHdtvDAvKhQr4NRFvR3eb_cfaB0E6HvH8fpfp8GhchgnXfAbSsBndLpF_4oqyrvcTRXdq_EGIzMe1Gt4ufPclbmz4R9jkZVneEowqvCs/s400/Apollo_CM_Sextant_Princible.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo Command Module sextant's principle of operation. By adjusting the shaft and <a href="https://en.wikipedia.org/wiki/Trunnion" target="_blank">trunnion</a> angles (As and At) either the astronaut or computer can superimpose two objects in sight. Also automatic operation is possible using electronic sensors.</i></span></td></tr>
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Much attention went into the design of this wide field scanning telescope so that the astronaut would have a good chance of recognizing stellar constellations and identifying stars. The enormous problem came from scattered light in the instrument washing out the visibility of dimmer stars. A really satisfactory engineering compromise among such things as the degree of articulation, the field of view, light traps, and sun shields was not found. <b><u>Only with the spacecraft turned so that the optics were on the shady side and without the sun illuminated earth, moon, or other spacecraft in the field could a good view of the stars be obtained.</u></b> This problem lessened in importance as actual mission techniques developed.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQW71tQULQu6aPBB8QlghvWJEdfMka8Z0pMguMfuMOMvPDH-JEbynvV7-0E5uEShBJJ7_GsVTOkpc-n4TlbponzpxuS1ArTZuHPySdTz81j6DalsaP0FhdCdixscJzO18rM2ZRJf23bDgJ/s1600/Apollo+17+Ron+Evans+conducts+a+guidance+and+navigation+exercise+in+mission+simulator.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="724" data-original-width="900" height="321" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhQW71tQULQu6aPBB8QlghvWJEdfMka8Z0pMguMfuMOMvPDH-JEbynvV7-0E5uEShBJJ7_GsVTOkpc-n4TlbponzpxuS1ArTZuHPySdTz81j6DalsaP0FhdCdixscJzO18rM2ZRJf23bDgJ/s400/Apollo+17+Ron+Evans+conducts+a+guidance+and+navigation+exercise+in+mission+simulator.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 17 Ron Evans conducts a guidance and navigation exercise in mission simulator optics.</i></span></td></tr>
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An early concept required that the inertial system be turned off most of the mission time in order to save spacecraft power. It would be turned on, aligned, and used only during the guidance and control of rocket maneuvers. For a number of reasons the operations policy changed so as to leave the inertial system active throughout the mission. The procedure then became one in which periodically, perhaps twice a day, the inertial measurement unit drifting orientation was corrected to the stars.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwIWuP_u5EUZWsPXgFSchmGUklXkUGbCIEuiogRRHmsJkestdDuqpP7VDaaKidX34hcTpSFmfX7JoCJX71AJWCgGTM330x0Gxi7qF9HlZjrhzaktuFTpvAe5_h8lsTYbPMhUhsKZGr-PRc/s1600/A11_Star_Chart-S1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1104" data-original-width="1600" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjwIWuP_u5EUZWsPXgFSchmGUklXkUGbCIEuiogRRHmsJkestdDuqpP7VDaaKidX34hcTpSFmfX7JoCJX71AJWCgGTM330x0Gxi7qF9HlZjrhzaktuFTpvAe5_h8lsTYbPMhUhsKZGr-PRc/s400/A11_Star_Chart-S1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 11 Star Chart</i></span></td></tr>
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To do this, the computer would use the inertial unit angles to point the sextant star line approximately to the selected star. The gyro drift would be small enough, however, that the star would appear in the sextant field of view. The astronaut would then center the image, thereby giving the necessary data to the computer to realign the inertial unit. In this way accurate inertial alignment was maintained throughout the mission. <i><b>Similarly, the computer could orient the spacecraft and point the optics close to any targets suitably specified by the astronaut.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPIkv3VPtRc7p2zZc_wC2i_nFoCiMASHeEV41xijnL3LhM0ZzELE6GxxJmR006WLVIxTps0CsJ0zhjRDHzKjczlR-jblfZGtqID2Ga0ZQsGjSCm03OqDsabff5riwfNUil8EnrR79jAUfe/s1600/NASM-A20010305001_PS01.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1065" data-original-width="1600" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPIkv3VPtRc7p2zZc_wC2i_nFoCiMASHeEV41xijnL3LhM0ZzELE6GxxJmR006WLVIxTps0CsJ0zhjRDHzKjczlR-jblfZGtqID2Ga0ZQsGjSCm03OqDsabff5riwfNUil8EnrR79jAUfe/s400/NASM-A20010305001_PS01.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>CM optics. Strong cover plate was required. Left 28x sextant, right 1x telescope.</i></span></td></tr>
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The scanning telescope, in spite of the scattered light problem with stellar targets, provided an excellent tracking instrument for navigation sightings to the earth or moon while in orbit around these bodies. For this required function, line-of-sight rates were too fast to use the sextant.<br />
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<b><i>Indeed, the precision of that instrument was not always needed</i></b>. The navigation angle was measured by the computer between the <b><i>pre aligned inertial unit</i></b> and the line of sight to the surface target being tracked by the astronaut.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5tvmDCkSwylcPbjHBdrPhh1MigLiHfZH5oTmeq_MAvMtTIdSrOtiWPSW3LiSDQeRdherjS4jxl4r7ofeLvd_njtAmg7eEL-x_4RwjGqUVD1LF6j05erYXnEgMhrsZqCem2M2o0_EtoB_n/s1600/NASM2012-02161.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1104" data-original-width="1600" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5tvmDCkSwylcPbjHBdrPhh1MigLiHfZH5oTmeq_MAvMtTIdSrOtiWPSW3LiSDQeRdherjS4jxl4r7ofeLvd_njtAmg7eEL-x_4RwjGqUVD1LF6j05erYXnEgMhrsZqCem2M2o0_EtoB_n/s400/NASM2012-02161.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Sextant on the left and telescope on the right side. CM optics cover opened.</i></span></td></tr>
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The orientation relationships between the inertial unit and the optical lines of sight in this fashion demanded strict limits on the alignment and relative flexures between these instruments. Bowditch designed them both to be mounted to a common light-weight but stiff and stable structure called a <b><i>navigation base</i></b>. With a kinematics mount, spacecraft strains could be prevented from being passed on to twists in this navigation base.<br />
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The complicating factor was that the optics objectives were in the hard space vacuum, while the eye pieces were in the one-third atmosphere cabin pressure. The total force of this pressure was about 3500 newtons and required careful consideration of the location of the force center with respect to the mounts. Relative motion was accommodated by a double walled metal bellows which provided the seal of cabin pressure.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvwzRnv9ImSW15kkYDeSrf77l2u5vLtE5PbkifGK1_4GHgA0r3naOkG2KgoCzcNBW22hroRyVNcOtxE0h3UPSB8qof6kb2COqn5N9SYjK-1ysrYAg0RGVGhTTXShAC9HyZgg7UkGV4aVGR/s1600/NASM-NASM2012-02162.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1067" data-original-width="1600" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvwzRnv9ImSW15kkYDeSrf77l2u5vLtE5PbkifGK1_4GHgA0r3naOkG2KgoCzcNBW22hroRyVNcOtxE0h3UPSB8qof6kb2COqn5N9SYjK-1ysrYAg0RGVGhTTXShAC9HyZgg7UkGV4aVGR/s400/NASM-NASM2012-02162.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>CM optics cover removed. The objectives were in the hard space vacuum, while the eye pieces were in the cabin pressure.</i></span></td></tr>
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Associated with the optics design was the question of the suitability of the earth and moon as navigation targets. Considerable theoretical and experimental work was undertaken early by <b><i>Dr. Max Peterson</i></b>, <b><i>William Toth,</i></b> and <b><i>Dr. Frederic Martin</i></b>.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpvtwGEtKQBNnbLmOyDwh28z33bVGCXMxk3k2m0DOlpfoMXgEIlnVrGTuVe30NXT9wjvt0olOLQH8c-6O_xdAhHHVrf0_ZZok0l2ZVqXEuuHQDrpr68qY2638qsw95szvJLZI2UvSIloOq/s1600/Dr_Fred_Martin_2002.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="376" data-original-width="317" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpvtwGEtKQBNnbLmOyDwh28z33bVGCXMxk3k2m0DOlpfoMXgEIlnVrGTuVe30NXT9wjvt0olOLQH8c-6O_xdAhHHVrf0_ZZok0l2ZVqXEuuHQDrpr68qY2638qsw95szvJLZI2UvSIloOq/s400/Dr_Fred_Martin_2002.png" width="336" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Fred Martin at the AGC Conference 2002</i></span></td></tr>
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The moon, without an atmosphere, had crisp visual features and horizon when they were illuminated by the sun. The earth on the other hand might have most if not all of its suitable landmarks obscured by clouds at the critical time. The sunlit earth horizon, due to intense scattered sunlight in the atmosphere, is invisible from space and no distinct visual locator can be identified.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi16EdT7p6cf8ed32A9zAwyQ9JyftYmKiz_TDnThG_5BhUBNQ8OIzeOH3OR6ZYtR-1AbAX1j1V89CMoUAfFHCYQxCWhBZje_kXjOM7TZF8TKqdK0T2a6MY-l7x5HIEDesz_CbVYFH_Hd8IN/s1600/MV5BMmM5NGQzNDUtZTJkMC00NTVjLThlNDUtMTk1ZjUzYTVmODU1XkEyXkFqcGdeQXVyNTQ1NzU4Njk%2540._V1_SY1000_CR0%252C0%252C1451%252C1000_AL_.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1000" data-original-width="1451" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi16EdT7p6cf8ed32A9zAwyQ9JyftYmKiz_TDnThG_5BhUBNQ8OIzeOH3OR6ZYtR-1AbAX1j1V89CMoUAfFHCYQxCWhBZje_kXjOM7TZF8TKqdK0T2a6MY-l7x5HIEDesz_CbVYFH_Hd8IN/s400/MV5BMmM5NGQzNDUtZTJkMC00NTVjLThlNDUtMTk1ZjUzYTVmODU1XkEyXkFqcGdeQXVyNTQ1NzU4Njk%2540._V1_SY1000_CR0%252C0%252C1451%252C1000_AL_.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>(Dr. Strangelove - a fictional 1960's film character played by Peter Sellers. Seller's character shows typical stereotypes of the time.)</i></span></td></tr>
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<i><span style="color: #274e13;">(YouTube video</span></i>: <a href="https://youtu.be/XfJTld0baG4" target="_blank">"The Making of Dr. Strangelove"</a>)<br />
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<b><i>Photometric equipment to measure the systematic change in brightness</i></b> with altitude above the true limb in the blue part of the spectrum was designed into the sextant along with an automatic star tracker to solve this problem. Later in history, for reasons of cost and complexity, these were removed. The visual sightings of the earth horizon was reexamined for navigation use. Simulations with <b><i>photometric fidelity</i></b> <i><span style="color: #274e13;">[in electronics, fidelity refers to the correspondence of the output signal to the input signal, rather than sound quality]</span></i> of the situation were devised.<br />
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It appeared that the human was capable of choosing some locator in the fuzzy horizon which he could duplicate with considerable accuracy. Before each mission, the navigator astronaut would come to the Instrumentation Laboratory to train on this simulator. With practice he could duplicate his sighting point within a few kilometers over the range of interest of distances to the earth. (Later on, early in his actual mission, he made several sightings to calibrate his horizon locator. -<i><span style="color: #274e13;">[To find an accurate Earth horizon is important at the re-entry phase.]</span></i>)<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaCiU11k0GoV5tT1U_E5ebVcaHbBnyDCe3Wc3y8LybCUX5I-TO-38TFT_1x52iLTuLAOss43r9P-1-_gAY0oad9Y02pQCIYvNqRCE60vhsjn6VxnJNQouLUuP7tVAVicne2ojUBuEuR-IM/s1600/EldonHall%2540300x300.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="300" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaCiU11k0GoV5tT1U_E5ebVcaHbBnyDCe3Wc3y8LybCUX5I-TO-38TFT_1x52iLTuLAOss43r9P-1-_gAY0oad9Y02pQCIYvNqRCE60vhsjn6VxnJNQouLUuP7tVAVicne2ojUBuEuR-IM/s400/EldonHall%2540300x300.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Eldon C. Hall, Apollo digital development</i></span></td></tr>
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The computer design was undertaken by <a href="https://en.wikipedia.org/wiki/Eldon_C._Hall" target="_blank"><b><i>Eldon Hall,</i></b></a> who had designed the <b><i>Polaris Missile Computer</i></b>. Laboratory members assisting him included <b><i>Dr. Raymond Alonso</i></b>, <b><i>Dr. Albert Hopkins,</i></b> and <b><i>Hugh Blair-Smith.</i></b> In addition they were supported by engineers from Raytheon, who worked with Hall on the Polaris computer.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9DZtG8PERJzmpc6eqy29Ho7PUbWHwqr7XAK05wH3MkD0rEHa3znVFTwEVepM2MuHDGblyJIue0VCX8glNazxlBv6TVXyFw_PLPiw0l5Y9SyKwcR9iLujmw0W7u5b05jqlLRLY-7bdNxt9/s1600/Albert_Hopkins.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="784" data-original-width="849" height="368" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9DZtG8PERJzmpc6eqy29Ho7PUbWHwqr7XAK05wH3MkD0rEHa3znVFTwEVepM2MuHDGblyJIue0VCX8glNazxlBv6TVXyFw_PLPiw0l5Y9SyKwcR9iLujmw0W7u5b05jqlLRLY-7bdNxt9/s400/Albert_Hopkins.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Albert Hopkins in the MIT film <a href="https://youtu.be/YIBhPsyYCiM" target="_blank">"Computer for Apollo"</a></i></span></td></tr>
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A compelling necessity was to design a reliable computer with sufficient capacity and speed yet with a very limited size, weight, and power drain.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZMMPmHnJqM-rRDoIpZSPP3Ra89iEgc_Hb0oWs2kHnz7D47LvNsQj6xEmDasrcgCdhSY7RKHN7Z9u55K0jYiUtZ-SM7Z2hiFhyd4a-OGLVKDv4j6JG1ZcxwTY4O4AfinXCFc1Q1fsgsvox/s1600/Hugh_Blair-Smith%2526Daughter%2540250x375.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="250" data-original-width="375" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiZMMPmHnJqM-rRDoIpZSPP3Ra89iEgc_Hb0oWs2kHnz7D47LvNsQj6xEmDasrcgCdhSY7RKHN7Z9u55K0jYiUtZ-SM7Z2hiFhyd4a-OGLVKDv4j6JG1ZcxwTY4O4AfinXCFc1Q1fsgsvox/s400/Hugh_Blair-Smith%2526Daughter%2540250x375.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Hugh Blair-Smith and daughter</i></span> </td></tr>
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The machine configuration chosen was a 16 bit, parallel, general purpose, real-time digital control computer, initially configured with magnetic core transistor logic, the change was soon made to an integrated circuit logic using technology being developed by the semiconductor industry.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPfjLlj7-FL9ncUrIX0tSzfbPlrI9kzvpqiphgiUozhZctzkPdWEu5M8i7D2-HyZAnBFgll-xpK7dxFOU2iMc3bKWcQ7KjeychVDLI_mWFl6vzv5GeJIbgnblnSTsv9D3LA_h5iu29Uc3T/s1600/LM_Guidance_Computer_LGC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="933" data-original-width="1092" height="341" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjPfjLlj7-FL9ncUrIX0tSzfbPlrI9kzvpqiphgiUozhZctzkPdWEu5M8i7D2-HyZAnBFgll-xpK7dxFOU2iMc3bKWcQ7KjeychVDLI_mWFl6vzv5GeJIbgnblnSTsv9D3LA_h5iu29Uc3T/s400/LM_Guidance_Computer_LGC.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Final LGC (Lunar Module Guidance Computer) block diagram showing all its inputs and outputs</i></span></td></tr>
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The deliberate choice was made to use only one type of integrated circuit logic, a three input NOR gate. Although wider variety could have substantially reduced the number of devices per computer, the resulting dedication in manufacture and quality control to the single circuit type gave important gains in reliability.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiih2mCIxW4F3XB5wincJIGDz3Mpf8INNndCXdxS4PH-GNqVEnrJezz1hHPSW4HaH6ZUN3hF0ouUvtF8D81DWN4Y__2kvJLpbGFtCxDXwgBG1IJsgTlZb9kOvfGb2ppRKe6wNBNcE6_LuhE/s1600/AGCrear%2540285x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="285" data-original-width="380" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiih2mCIxW4F3XB5wincJIGDz3Mpf8INNndCXdxS4PH-GNqVEnrJezz1hHPSW4HaH6ZUN3hF0ouUvtF8D81DWN4Y__2kvJLpbGFtCxDXwgBG1IJsgTlZb9kOvfGb2ppRKe6wNBNcE6_LuhE/s400/AGCrear%2540285x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Rear view of the AGC computer showing removable core-rope modules that contain the flight computer programs. Program modules could be swapped any time if required.</i></span></td></tr>
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The fixed memory was the high density <b><i>read only core rope</i></b> developed in connection with the Mars probe. This meant that the contents of this indestructible memory had to be determined early in order to allow time for manufacture.<br />
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Rather than a disadvantage, risky last minute changes of the program just before flight were physically prevented. A rope memory program was necessarily well tested before it flew on an Apollo mission.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNrpYkHiG9iRbkLy0OQ-KzxpMQOFZ7V4hUn_7hirLw4cuW-snqHo0M6Loh0zZAKHXoM9xMkCGxYSmaN2OGI2NOqZepPyyBZ_xcRQvcgBOHnBa60NIojzi7dymTbuGug_oG1zN_j0eC2ZHi/s1600/Agc_rope.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="420" data-original-width="664" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNrpYkHiG9iRbkLy0OQ-KzxpMQOFZ7V4hUn_7hirLw4cuW-snqHo0M6Loh0zZAKHXoM9xMkCGxYSmaN2OGI2NOqZepPyyBZ_xcRQvcgBOHnBa60NIojzi7dymTbuGug_oG1zN_j0eC2ZHi/s400/Agc_rope.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>AGC core-rope memory module.</i></span></td></tr>
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A coincident-current <b><i>magnetic erasable memory</i></b> provided for temporary storage. The size was kept to a minimum both in the number of words and in the 16 bits per word,for low power consumption. The initial decision in the Block I design was 1024 words of erasable, but this was doubled for Block II based upon the experience in programming the earlier machine.<br />
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Without changing the computer volume, the fixed memory likewise grew from an initial 12,000 words to 24,000 words in Block I to 36,000 in Block 11. To the programmers, even these larger numbers were to seem inadequate as the functions to be performed in the computer on the lunar missions expanded substantially over original forecasts.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjd_1gQmwJU4xhNqaKm_k87Bl5o-cTMgqNQqDE8zkVEBkEY7pAmA_POZV3sOrT-xtzOP_JqbUgEDxdtLxaLuJHBdRXO0HT4coVj88AKOt-tSvrnK_cKL05sGUZQE0yQSZY69TnYnu1co9x/s1600/Apollo_1024_bit_core_memory_module.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="596" data-original-width="1184" height="201" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjd_1gQmwJU4xhNqaKm_k87Bl5o-cTMgqNQqDE8zkVEBkEY7pAmA_POZV3sOrT-xtzOP_JqbUgEDxdtLxaLuJHBdRXO0HT4coVj88AKOt-tSvrnK_cKL05sGUZQE0yQSZY69TnYnu1co9x/s400/Apollo_1024_bit_core_memory_module.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 1024 bit core memory module</i></span></td></tr>
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Both memories, operating on a 12 microsecond cycle time, were configured to look identical to the program. A very limited basic instruction repertoire was expandable by powerful <b><i>interpretive routines</i></b> written by <b><i>Charles Muntz</i></b> which saved program word use at the cost of speed.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJNwrlVGvcrFTxCTM47ZH7_ssDk9gRgjkWBRLDSQhGsygkVsgGw2ekfpYrAgvMKregoo3IPwy1ziyjNV8pmYhQ__o_a31kJZ4sjn8IqdVN95gjIH1QTZf7iitS0II4o82jy7e5vu5XJM0m/s1600/Charles_A_Muntz.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="163" data-original-width="200" height="326" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJNwrlVGvcrFTxCTM47ZH7_ssDk9gRgjkWBRLDSQhGsygkVsgGw2ekfpYrAgvMKregoo3IPwy1ziyjNV8pmYhQ__o_a31kJZ4sjn8IqdVN95gjIH1QTZf7iitS0II4o82jy7e5vu5XJM0m/s400/Charles_A_Muntz.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Charles A Muntz, later years</i></span></td></tr>
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Over 200 input and output circuits for numerous interfaces with other hardware were provided to perform the real-time control function. Certain discrete input and timing signals could be arranged to interrupt the program underway so that urgent tasks could be serviced in real time without the need of continuously scanning inputs.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgTG2uglJxDccbCCM2qufAElIsUMysW3gSzIfIWh1QiGNZjYfPbne4xffuY9EqnzIyn25xQcpRvK9FvYrnyjr5EIslvmpOO_-GQlsfPp-5C1SXvfogxVnE9ZupEhyphenhyphenswg8F1ga2xMR2LZo1/s1600/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto; text-align: center;"><img border="0" data-original-height="934" data-original-width="900" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgTG2uglJxDccbCCM2qufAElIsUMysW3gSzIfIWh1QiGNZjYfPbne4xffuY9EqnzIyn25xQcpRvK9FvYrnyjr5EIslvmpOO_-GQlsfPp-5C1SXvfogxVnE9ZupEhyphenhyphenswg8F1ga2xMR2LZo1/s320/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966.jpg" width="308" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo DSK, AGC 's Display and Keyboard</i></span></td></tr>
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<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Link</span></i>: <a href="https://dodlithr.blogspot.fi/search/label/DSKY" target="_blank">Some detailed articles about the DSKY.</a><br />
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A most important input/output function was provided by a display and keyboard (<a href="https://dodlithr.blogspot.fi/search/label/DSKY" target="_blank">DSKY</a>) and associated software control ingeniously designed by <b><i>Alan Green</i></b>. The keyboard allowed the input of the 10 digits and seven other coded functions on separate keys.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzinYPpzfGVLl6Z4J08Stq7lQNVPZmnHUQ0CeGAG-RcSd6FqZVb2qsxFv3cgmg3s1Jd4vDyvhEKgenam_n4MnOPYwZatfe8BRhQzY7PTDm8UnjXLdrzJDFbjCskBI4qUHsJItEBQfOqBu5/s1600/DskyDiagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="459" data-original-width="946" height="193" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzinYPpzfGVLl6Z4J08Stq7lQNVPZmnHUQ0CeGAG-RcSd6FqZVb2qsxFv3cgmg3s1Jd4vDyvhEKgenam_n4MnOPYwZatfe8BRhQzY7PTDm8UnjXLdrzJDFbjCskBI4qUHsJItEBQfOqBu5/s400/DskyDiagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>DSKY Programming Model</i></span></td></tr>
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The display included three, 5 digit numbers plus sign to indicate numerical data, and three, two digit numbers to identify the function being performed by numeric codes for "verbs", "nouns", and "program". The verb-noun format permitted a sort of language of action and object such as "display-gimbal angles" or "load-star number." The program number identified the major background computation underway in the machine.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0sfl5Y_QTTl8yW8yXK6M9DOfwHeTOOJ1yfCJKYzwefe2-RVtTZ8Eqab7Rw7248aRoFnV7PvMkqxGe5oIhy3hB7bkPWyCHPqJb5QCDZqrF8tUs3ZoXAddROa_Wv4EUjRqKp26ve10SPgUB/s1600/DSKY_Electronics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="837" data-original-width="638" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0sfl5Y_QTTl8yW8yXK6M9DOfwHeTOOJ1yfCJKYzwefe2-RVtTZ8Eqab7Rw7248aRoFnV7PvMkqxGe5oIhy3hB7bkPWyCHPqJb5QCDZqrF8tUs3ZoXAddROa_Wv4EUjRqKp26ve10SPgUB/s400/DSKY_Electronics.png" width="303" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>DSKY Display utilized over 100 latching relays all together to show 21 numbers (and 3 +/- signs)</i></span></td></tr>
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With this display and keyboard the astronaut had enormous flexibility and power in communicating with and directing the computer's operation. Many hours of study and training time on real equipment were required by the astronauts.<br />
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An early reticence by crew members was in time replaced by enthusiasm and confidence in their ability to use the computer to manage many aspects of their mission. Dr. Draper's early statement about training engineers versus training pilots might have been true, but the astronauts with their pilot (and engineering) background developed a competence in the guidance and navigation of Apollo which could not have been surpassed.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1qNV0eiwAXSstetFuYFpaQewT-q4ktnMtRQoz_zhHmTs4NycGdRXqED_xxTHQ9yxx2pFzjo7XIqzDH2QVWtecbyjHrBn9Q65PkvCqTMp6YMTn148u526vby2_O-DSBApIPAKVjyTEpfgy/s1600/3321443_page.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="289" data-original-width="400" height="288" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1qNV0eiwAXSstetFuYFpaQewT-q4ktnMtRQoz_zhHmTs4NycGdRXqED_xxTHQ9yxx2pFzjo7XIqzDH2QVWtecbyjHrBn9Q65PkvCqTMp6YMTn148u526vby2_O-DSBApIPAKVjyTEpfgy/s400/3321443_page.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo ACA, Attitude Controller Assembly</i></span></td></tr>
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The computer display and keyboard permitted the crew to operate most guidance, navigation, and control functions. In addition the left hand translation command controller (<b><i>TTCA - Thrust/Translation Controller Assembly</i></b>) and the right hand rotational command controller (<b><i>ACA - Attitude Control Assembly</i></b>) were used appropriately for these maneuvers when commanded manually for computer action.<br />
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Those operations associated with the use of the optics in manually tracking earth, moon, and stellar targets and in making the navigation angle measurements had appropriate controllers near the eye pieces.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiScnc7gyUr8QqLiXwYWztd9Pd_j4fleRxHPJVew1VsqdZ8NjSRr-Lzer6-6qmrp9L4VNbfOCdf0MexwRz9KxPVjs9j-4QdyQSxxXbViPZdlJS2lW4jMwafeqfxhh3VEP808otULIL092g/s1600/18n5abpc0bjktjpg.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="349" data-original-width="636" height="218" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiScnc7gyUr8QqLiXwYWztd9Pd_j4fleRxHPJVew1VsqdZ8NjSRr-Lzer6-6qmrp9L4VNbfOCdf0MexwRz9KxPVjs9j-4QdyQSxxXbViPZdlJS2lW4jMwafeqfxhh3VEP808otULIL092g/s400/18n5abpc0bjktjpg.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo TTCA, Thrust/Translation Controller Assembly</i></span></td></tr>
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Many of the hardware design decisions were easily made in trade-off among members of the design team at the Instrumentation Laboratory. The experience of the industrial support contractors and their concern for manufacturing predictability influenced many other decisions. Accommodations had to be made to recognize test, checkout, and mission operations of the astronauts and the ground mission control.<br />
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The largest problem, however, was reaching agreement on those design features which were affected by and influenced the hardware design of the spacecrafts. This was embodied in the negotiations of the so-called interface control documents which were to be agreed upon and signed off. Then each party could proceed with the confidence that he was protected against changes on the other side of the interface from affecting his design.
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Numerous "<b><i>coordination meetings</i></b>" were held starting in 1962 between the Instrumentation Laboratory and North American with NASA participation in order to negotiate these decisions affecting both parties in the design of the command and service modules. In early 1963 coordination meetings with Grumman concerning the interacting decisions on the Lunar Module started.
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One complicating ground rule, which in the end returned enormous savings, was the self imposed ground rule of the designers that as much as possible identical guidance <span style="color: #4c1130;"><i>(From this point on, "guidance" will mean "guidance, navigation, and control".)</i> </span>hardware elements would be used in both the <b><i>Command Module</i></b> and <b><i>Lunar Module</i></b>. The difficulty with this was that a successful agreement with North American for the Command Module interface could be upset by a second negotiation with Grumman for the same piece of guidance hardware in the Lunar Module.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihflQrQArhJ1ftYTqpv4plQRxQZKSApKJAj4jZBJ8CbcEmd0tu85BhniE9yEJ7QbH3urdiAZcbYOh2KKQFBbI6p1Wu2b-CS7qFupK9GP5bJ8YwHNAlV42kvlaVzB0TdIs1dIc5RKbRKf3G/s1600/c150a.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="408" data-original-width="536" height="303" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihflQrQArhJ1ftYTqpv4plQRxQZKSApKJAj4jZBJ8CbcEmd0tu85BhniE9yEJ7QbH3urdiAZcbYOh2KKQFBbI6p1Wu2b-CS7qFupK9GP5bJ8YwHNAlV42kvlaVzB0TdIs1dIc5RKbRKf3G/s400/c150a.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>An early Lunar (Excursion) Module L(E)M prototype had seats and a round egress hatch in it. Later on the seats were removed and the hatch become rectangular.</i></span></td></tr>
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The effort paid off in manufacture, test, and astronaut training. <b><i><u>The big guidance items, the inertial measurement unit and the computer as they came of the production line could then go to either spacecraft.</u></i></b> Most of the small hardware components of the guidance were similarly interchangeable when the same function was accomplished in each spacecraft. The guidance turned out to be the only significant hardware that had this interchange ability. Most other spacecraft elements of the Command and Service Modules were not usable on the Lunar Module and vice versa.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6CaQ7k6qDKWsswGM8nBo3Xrz0sUCXWdjG5oo28pisTa5-270iPR3LKFmQLt32rdmmSJYJL7hXkhmzI-x-UayVOf-x-cCVZ1Swf0u2KiLvruLw4ZncLeLLKmhE9n6k4j7n6Mm2jHBafkMo/s1600/LEM_PGNCS_Components.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="662" data-original-width="831" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6CaQ7k6qDKWsswGM8nBo3Xrz0sUCXWdjG5oo28pisTa5-270iPR3LKFmQLt32rdmmSJYJL7hXkhmzI-x-UayVOf-x-cCVZ1Swf0u2KiLvruLw4ZncLeLLKmhE9n6k4j7n6Mm2jHBafkMo/s400/LEM_PGNCS_Components.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Location of the guidance equipment in the LM</i></span></td></tr>
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The first important interface to be negotiated was the location of the guidance equipment in the spacecraft. North American and the Instrumentation Laboratory first examined wall space to the left of the left hand couch where the astronaut could use the eye pieces to make sightings. The final location in CM was on the lower wall at the foot of the center couch. This required that the astronaut using the equipment would have to leave the couch and stand in the lower equipment bay.
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For those stressful times when the crew were constrained to their couches in CM, all the guidance equipment except the optics could be operated through the computer from the main panel within reach using a main panel computer display and keyboard. A particular worry about the lower wall location for the guidance and navigation was that the optics there penetrated the hull on the hot side of the command module during return through the atmosphere. initially a door covering these optics with a heat shield was provided for protection but was later removed from the design when analysis showed the <i>hardware could tolerate the stress with suitable additional design changes</i>.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBLDetPnqtp4mXJJIADHrtcCQQuoxnQm3s6unG6APSJ_4odSqXRMXpLqUiwESVtqKMGZA_UOQCBF86-t5vKeuahaP8rftdXiejlmIeE-Wr2GDwJwmYj6qosDq2YUBndT1lDw6EZaK0G8_s/s1600/James_Nevins_Jr.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="181" data-original-width="136" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBLDetPnqtp4mXJJIADHrtcCQQuoxnQm3s6unG6APSJ_4odSqXRMXpLqUiwESVtqKMGZA_UOQCBF86-t5vKeuahaP8rftdXiejlmIeE-Wr2GDwJwmYj6qosDq2YUBndT1lDw6EZaK0G8_s/s400/James_Nevins_Jr.jpg" width="300" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>James Nevins, Jr. - contributed to the Apollo Space Program as one of the architects of the Apollo Guidance Computer.</i></span></td></tr>
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Once the guidance equipment was located in the spacecraft, <b><i>James Nevins</i></b>, Nugent, and Bowditch immediately started an overall configuration design and mock-up so that <b><i><u>quite early the astronaut operations with the equipment could be tested and revised as needed</u></i></b>.
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Because of the operational complexity of the mission, the first mock-up included a film projector to display procedures, maps, and charts to the astronaut. However, as the design of the whole operation progressed and the logic of the crew operation with the computer evolved, the film viewer was removed from the design. <b><i>Hand-held notebooks</i></b> such as used in Mercury and Gemini would suffice.
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The exercise of the mock-up with a pressurized space suit emphasized a problem. With his helmet;. on, the astronaut could not get his eye close enough to the eyepieces to perform his sighting tasks. The solution was to design special eyepieces, necessarily bulky but with sufficient eye relief, which could be attached in place of the regular eyepieces when sightings in the helmet were required. The storage of these large units was found conveniently in the space recently vacated by the film viewer.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS_U0MP-lvmHsnMtD-3BLXW4oWEiqWD__3mmGoQ2YrfekiDQ2r2DIKwJu9Zi6IrujU_LvGLaq7nLHJUtkC3HHa0D8A82v7ZiiJ1-breh0Q7R_gkb8aOefEbYLG-xt_SQrVBxJBgHwexg69/s1600/Ain_Laats.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="254" data-original-width="400" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjS_U0MP-lvmHsnMtD-3BLXW4oWEiqWD__3mmGoQ2YrfekiDQ2r2DIKwJu9Zi6IrujU_LvGLaq7nLHJUtkC3HHa0D8A82v7ZiiJ1-breh0Q7R_gkb8aOefEbYLG-xt_SQrVBxJBgHwexg69/s400/Ain_Laats.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Ain Laats, later years</i></span></td></tr>
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The design verification of the guidance hardware was initiated by <b><i>Ain Laats</i></b> in his systems test laboratory using specialized test equipment to examine the first production units of the assembled system. Of particular concern was the interactions among the inertial and optical sensors, the computer, the computer software, and astronaut functions when working altogether. One of the earliest computer programs called SUNRISE was coded for this function. Special computer control program routines, hardware test code, and prelaunch systems functions were developed in this activity by <b><i>Thomas Lawton</i></b>, Ain Laats, <b><i>Robert Crisp</i></b>, and others.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYOigbxpIrcGwZLKuBsphVbASutHZyMiTjZeUu18ynGH_58RMjf5rF1wPLAKSzpTa2UcHtTvWIvH0ji7K_7-aTyRilMjq2Jm0xa8SxTIDXOJvwDUAae0WAuJUh0i3dADx75yzWRuU176Jy/s1600/Thomas_Lawton_.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="391" data-original-width="275" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYOigbxpIrcGwZLKuBsphVbASutHZyMiTjZeUu18ynGH_58RMjf5rF1wPLAKSzpTa2UcHtTvWIvH0ji7K_7-aTyRilMjq2Jm0xa8SxTIDXOJvwDUAae0WAuJUh0i3dADx75yzWRuU176Jy/s400/Thomas_Lawton_.jpg" width="281" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Thomas Lawton worked for General Electric on the Polaris Missile Project and for MIT/Draper Lab on the Apollo Space Flights.</i></span></td></tr>
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<i><span style="color: #274e13;">YouTube video</span></i>: <a href="https://youtu.be/A3elkTYzqdw" target="_blank">"Ain Laats interview"</a><br />
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An early concern with equipment reliability produced requirements for in flight fault diagnosis and repair. The Block I design carried spare modules which could be plugged into sockets in place of failed modules. However, an event in the last Mercury spacecraft flight in May 1963, changed this in flight repair policy. On the 19th orbit the Mercury automatic control system failed so that astronaut Gordon Cooper had to fly the last three orbits of the mission manually.
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The diagnosis of the problem was moisture and corrosion of electrical connections due to the high humidity and contamination accompanying the human in his cabin. From then on <b><i>Apollo hardware designs in the cabin were required to be sealed from moisture</i></b>. This eliminated plug in spare modules since in flight usable connectors could not be satisfactorily sealed without weight penalties. However, even for fixed modules, the sealing led to weight increases because the packages had to withstand the large cabin pressure changes without buckling.
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Without the in flight repair, the concern for reliability remained so that the initial Block II design provided for two identical computers in the command module operating in parallel for redundancy. This seemed to be excessively conservative to <b><i>Cline Fraiser</i></b>, of the Guidance and Control Division in Houston, and he directed the return to the single computer concept. The wisdom of his decision was borne out in that no in flight computer failures occurred.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0Te5mmVG3VrJdQPXI5x8t5fUz4mjO4tl1RDL-HYD636kwRbkdOkas3d3GrdyDJBhcTSNnTJQZRCAiziq8rCn5mpY-2AqMWn5aT8Fp5GZ6Jgc_T7dLkB44X8tJxsPdUpu1Viih6fukPlks/s1600/Cline-Frasier-with-wife-Gretchen-and-WSU-award-web.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1143" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0Te5mmVG3VrJdQPXI5x8t5fUz4mjO4tl1RDL-HYD636kwRbkdOkas3d3GrdyDJBhcTSNnTJQZRCAiziq8rCn5mpY-2AqMWn5aT8Fp5GZ6Jgc_T7dLkB44X8tJxsPdUpu1Viih6fukPlks/s400/Cline-Frasier-with-wife-Gretchen-and-WSU-award-web.jpg" width="285" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Cline Frasier with wife Gretchen after receiving the Washington State University Alumni Association’s Alumni Achievement Award in recognition of his contributions to transportation safety, including in U.S. manned spacecraft, and his support of WSU scholarships, </i></span><i style="color: #cc0000; font-size: medium;">May 4, 2016 </i></td></tr>
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<i><span style="color: #274e13;">YouTube video:</span></i> <b><i><a href="https://youtu.be/9FCii5-Etcg" target="_blank">"Digital Autopilot for Apollo: A Radical Change - Cline Frasier - 2004"</a></i></b><br />
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The combined failure rate both pre flight and on missions was a small fraction of that of any other computer designed then or since for aerospace application. Such near perfect reliability was achieved at considerable effort, attention to design, a deliberate constraint to a minimum number of different parts, a detailed engineering qualification of design and components, and 100% stress testing of the parts to be used in manufacture.
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The concern for safety identified backup hardware. In the command module North American provided a simple, independent panel instrument with a single accelerometer which was called an <b><i>Entry Monitor</i></b>. Although never needed for backup use, it was useful to the astronauts as an independent means to watch the velocity change of maneuvers being made by the primary system. Similarly in the Lunar Module, Grumman provided through <a href="https://en.wikipedia.org/wiki/Hamilton_Standard" target="_blank"><b><i>Hamilton Standard</i></b></a> and <a href="https://en.wikipedia.org/wiki/TRW_Inc." target="_blank"><b><i>TRW</i></b></a> an independent abort guidance system (<b><i>AGS</i></b>) for a safety backup and also used as an independent monitor of the primary Lunar Module system.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqyE-vmV7f54xWva3a_HDLsiS_B9t4PIbdec0dtNZFmfcMNelbZKFmrljx9vsuRTSyZhRL3clBpvfqvUWxsRBPgBQ6VzWUBN7yquwBK9C93zhrQWJJ6Wn3nnNmWV2Yb_n9skB20Av03dl0/s1600/Robert_C._Duncan%252C_DARPA_Director%252C_1985%25E2%2580%25931988.jpeg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1280" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqyE-vmV7f54xWva3a_HDLsiS_B9t4PIbdec0dtNZFmfcMNelbZKFmrljx9vsuRTSyZhRL3clBpvfqvUWxsRBPgBQ6VzWUBN7yquwBK9C93zhrQWJJ6Wn3nnNmWV2Yb_n9skB20Av03dl0/s400/Robert_C._Duncan%252C_DARPA_Director%252C_1985%25E2%2580%25931988.jpeg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Robert C. Duncan (engineer)</i></span></td></tr>
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As work entered 1964, it appeared that necessary interface decisions between the guidance hardware and the spacecrafts were lagging. To meet this problem <b><i><a href="https://en.wikipedia.org/wiki/Robert_C._Duncan_(engineer)" target="_blank">Dr. Robert C. Duncan</a></i></b>, the Chief of the Guidance and Control Division at Houston, instituted and chaired a series of <b><i>Guidance Implementation Meetings</i></b>. The first meeting involving North American in the design decisions concerning the Command Module guidance system took place in June. Following meetings were held approximately <b><i>biweekly</i></b> until February 1965.
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A second set of meetings with Grumman on the Lunar Module guidance and navigation occurred at the same pace between September 1964 and April 1966. These meetings followed a tight agenda of technical issues to be resolved, and involved presentations by the spacecraft designer, the Instrumentation Laboratory, and occasionally other interested parties. Following this, Duncan either made a decision which was then incorporated in the appropriate <b><i>Interface Control Document</i></b>, or he requested further study and scheduled new presentations at a future meeting.
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A very significant decision took place early in this period concerning the implementation of the spacecraft attitude control auto pilots. Prior to this time, this function was to be performed by analog hardware under design responsibility of the spacecraft manufacturers. These analog auto pilots, which flew the Block I spacecrafts, were satisfactory, but lacked flexibility and required extensive specialized hardware.
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It was Duncan who made the decision in June 1964, that <b><i>the auto pilots should be done digitally utilizing the hardware of the guidance system</i></b>. To accommodate these new tasks, the speed of the computer was doubled and a much larger instruction repertoire was provided. Input and output interfaces also had to expand in order to send signals appropriately to the individual attitude jets, to the main engine gimbals, and to the thrust level servos, and in addition to receive the appropriate feedback signals from some of these elements. The memory capacity had been increased earlier for the lunar mission and was considered adequate for the auto pilots.
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Duncan's decision came with considerable controversy. The antagonists had shown that even expanded, the computer memory was insufficient and the computer was too slow to perform the necessary wide bandwidth control. They were right if one used the digital computer to perform digitally the same data processing handled by the analog circuits. The advocates argued that the proposed implementation would capitalize upon the flexibility, and nonlinear complex computations, natural to a digital computer.<br />
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It was the right decision. By skillful design only 10% of. the computer memory was devoted to the auto pilots and only 30% of computer computation time was needed during times of high Autopilot activity. A significant amount of complex hardware was eliminated, and moreover, the flexibility of the digital computer delivered better control performance and considerable improvements in efficiency in conserving the spacecraft fuel.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyzrU0ydBhrLAZSy9ZsmxjSZrmUbokc7iGFi839sn3rluJq8ZfchUSKCpoXns1n6UxqyUAEvBf1y-A83TnDQVP3NnvPjnHxTuMtwL2f_y8LToyXbYbAmeEEzh4a4kIU-ILvxjZFv7t8dch/s1600/NASA+MSC+Roundup+Sep+10+1971.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1187" data-original-width="858" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyzrU0ydBhrLAZSy9ZsmxjSZrmUbokc7iGFi839sn3rluJq8ZfchUSKCpoXns1n6UxqyUAEvBf1y-A83TnDQVP3NnvPjnHxTuMtwL2f_y8LToyXbYbAmeEEzh4a4kIU-ILvxjZFv7t8dch/s400/NASA+MSC+Roundup+Sep+10+1971.png" width="288" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. Kenneth J. Cox (right) of the Systems and Analysis Branch, Guidance and Control Division, receiving the AIAA Mechanics and Control Flight Award 1971. The award was jointly given to to Cox, Cherry and Widnall. (MSC Space News Roundup Sept. 10, 1971)</i></span></td></tr>
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The designs were the product of <b><i>Dr. William Widnall,</i></b> <b><i>Gilbert Stubbs</i></b>, and <b><i>George Cherry</i></b> at the Instrumentation Laboratory and <b><i>Dr. Kenneth Cox</i></b> at the <b><i>Manned Spacecraft Center.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_tP5pGORXMyMV8hLZYyCYJq4xJZ4uznw7SyYAeCgkpW8NhutyopfxhuJll9fgvbVvHTUjlkt4W7YB-DKyrTj_QO4WOrrgT4806qwhyphenhyphencW02n1jSuSiPwB0yOoWmNxHgy5K0s_qHWZIAcuK/s1600/George_Cherry%2540252x200.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="252" data-original-width="200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_tP5pGORXMyMV8hLZYyCYJq4xJZ4uznw7SyYAeCgkpW8NhutyopfxhuJll9fgvbVvHTUjlkt4W7YB-DKyrTj_QO4WOrrgT4806qwhyphenhyphencW02n1jSuSiPwB0yOoWmNxHgy5K0s_qHWZIAcuK/s400/George_Cherry%2540252x200.jpg" width="317" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>George Cherry</i></span></td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1R6bj7yX9NegN8kaSxFSBDC8UwmIjbQQYPU_Lt1HrZZWNwn1OMS-aI5FbLsjQv3hHPEvQEQ8tDNaSbh9M0p3aUd_Y0jfQxZp1SlZdHkpLMDbdtwvAXV2k3paRM0u4ZTopHPc_6M4jXGV/s1600/William_Widnall.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="360" data-original-width="480" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgO1R6bj7yX9NegN8kaSxFSBDC8UwmIjbQQYPU_Lt1HrZZWNwn1OMS-aI5FbLsjQv3hHPEvQEQ8tDNaSbh9M0p3aUd_Y0jfQxZp1SlZdHkpLMDbdtwvAXV2k3paRM0u4ZTopHPc_6M4jXGV/s400/William_Widnall.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Dr. William Widnall</i></span></td></tr>
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<i><span style="color: #274e13;">YouTube video 2008</span></i>: <a href="https://youtu.be/4Vf6Y98ZjwQ" target="_blank"><b><i>"Widnall on Apollo's guidance, navigation, and control"</i></b></a><br />
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With the satisfactory conclusion of the hardware Implementation Meetings, the designers were able to complete their tasks with reasonable assurance that the requirements would not change. This turned out to be true for the most part. The significant event affecting this was the February 1967, fire on the launch pad and the tragic loss of three astronauts. <b><i>More stringent specifications of fire resistance</i></b> in the cabin's pure oxygen atmosphere turned out to be reasonably straight forward to meet for the guidance equipment.
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Except for this, the hardware design remained relatively stable after 1965. This year 1965, however, was the peak year of hardware activity in which almost 600 man years of effort on guidance hardware was expended at MIT out of an MIT total for the hardware part of the program of approximately 2,000 man years. Hardware problems did arise after 1965 but it usually turned out that the expense in dollars and time in solving them by redesign could be avoided <b><i><u>by putting the burden of adapting to the problem on the computer program software</u></i></b>. This was also true of hardware problems in other parts of the spacecraft."
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<b><span style="color: #0c343d;">Software Design /10/
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"<b><i><u>Adapting to hardware problems</u></i></b> was only one of the many things which made generating the computer program software difficult. The primary complication was that the details of the mission continually changed and indeed were difficult to get defined in the first place. Then too, so many different programs were needed - different programs for the <b><i>Block I</i></b> and <b><i>Block II</i></b> computer, different programs for the <b><i>unmanned</i></b> and <b><i>manned</i></b> flights, different programs for the <b><i>earth</i></b> orbital and <b><i>lunar</i></b> missions, and different programs for the <b><i>Command Module</i></b> computer and the <b><i>Lunar Module</i></b> computer.
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<b><i><u>The effort needed for the software turned out to be grossly underestimated.</u></i></b> Until the first lunar landing in 1969, approximately 1,400 man years of effort at MIT was applied to the task. The peak activity occurred one year earlier in 1968 with a manpower total of <b><i>350</i></b>.
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Parts of the computer programming were accomplished early and were essentially independent of mission objectives. These included the basic code for the computer executive system, sequence control, timing and interrupt instructions, unchanged since originally designed by Dr. Laning, and the management of the interfaces with the computer display and keyboard unit, telemetry, etc.
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Also completed relatively early were the complex but not time-critical data processing routines of navigation, guidance targeting, trajectory extrapolation and lunar ephemeris calculations. Much of the analytical and algorithmic foundation for these came from Battin's earlier work for the unmanned space mission studies. For Apollo, Dr. Battin, <b><i>Dr. James Miller</i></b>, and <b><i>Norman Sears</i></b>, and other analysts made significant improvements in the efficiency and performance of these routines, many of which were of fundamental significance.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDVS2zmZDpCC-QyhoD1qkSlUbABs06GkYvzwb6YsGr5MN0p8mZ46l_2j0EY-TtSHfr4vyV0cWNuChhH9yo3mgtARi9_di9fVIn4a7W9J5RKD4kMyhtnQuYBG9xtJCOjmYJSR84rUsZk7W6/s1600/NormSears%2540300x300.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="300" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDVS2zmZDpCC-QyhoD1qkSlUbABs06GkYvzwb6YsGr5MN0p8mZ46l_2j0EY-TtSHfr4vyV0cWNuChhH9yo3mgtARi9_di9fVIn4a7W9J5RKD4kMyhtnQuYBG9xtJCOjmYJSR84rUsZk7W6/s400/NormSears%2540300x300.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Norman Sears</i></span></td></tr>
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The digital auto pilots, guidance steering, and other mission specific functions operating during the more stressful parts of the flights required considerable coordination with external agencies - the spacecraft designers, the Manned Spacecraft Center, and the astronauts. Several formal data exchange procedures were attempted, but the most effective in many cases were the direct personal contacts the individual analysts and programmers established with others who they learned had the accurate information.
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The computer program requirements were recorded for each mission by the Instrumentation Laboratory in a multi volume document called the <b><i>"Guidance System Operating Plan"</i></b> developed initially by <b><i>John Dahlen</i></b> and James Nevins. However, the often tardy publication of these plans made them more of a report of what was in the code rather than a specification of what should be coded. The individual programmers also generally drew their detailed flowcharts after the code was written. Standard format flowcharts were generated manually by a large special documentation team.
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The very early programs for the first few unmanned earth orbital test flight s were each put together by a small dedicated group led by a chief engineer-programmer. For the first command module flight, <b><i>Alex Kosmala</i></b> spent many weeks of long hours leading the design and coding of program <b><i>CORONA</i></b>. Similarly, <b><i>Daniel Lickly'</i></b>s great personal effort produced the program <b><i>SOLARIUM</i></b>. Each of these was an amazing tour-de force which was impractical for the more complex manned missions. Each of these later missions was assigned the responsibility of a senior engineer who assumed a more technical management role for the program.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfQ2-6qoo9XqxHsIkFLxm1Uvs63bI2zoP718FuTf5ElH4CAwOt-1YsSP7nrKcu7L5s6EeLKE1zAndxSV-Qa71rOF0ZcHevvJGfjS-pMcmP0DiW_TMBeq3zhLTSUjLXsTTv7JjezgfLzA45/s1600/Lickly_Hamilton.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="410" data-original-width="300" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjfQ2-6qoo9XqxHsIkFLxm1Uvs63bI2zoP718FuTf5ElH4CAwOt-1YsSP7nrKcu7L5s6EeLKE1zAndxSV-Qa71rOF0ZcHevvJGfjS-pMcmP0DiW_TMBeq3zhLTSUjLXsTTv7JjezgfLzA45/s400/Lickly_Hamilton.jpg" width="292" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Margaret Hamilton and Dan Lickly, successive chiefs of the software group</i></span></td></tr>
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The task first was to partition the job suitably for the analysts, specification writers, programmers, test engineers, and documentation specialists. The leader established schedules and progress milestones, reassigned resources to solve inevitable problems, and generally was responsible for the quality of the program. Names notable here are Dr. James Miller for the first Lunar Module program <b><i>SUNBURST</i></b>, Dr. Frederic Martin for the Command Module program <b><i>COLOSSUS</i></b>, and George Cherry for the Lunar Module program <b><i>LUMINARY</i></b>, These last two were the programs used for the lunar landing missions. Martin and Cherry also did a substantial part of the design of the powered flight guidance steering functions for these programs. <b><i>Alan Klumpp</i></b> made major contributions to the landing program in the Lunar Module. Daniel Lickly established the atmospheric entry design for the Command Module.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbcHuObneLSLZ1Xru2uKbI5nQrLg7FcFxWGQBcLUWVGYaCXVSQKJeKQssIK5CcvcxQDTlyNsHDTDwZc4JLxFWvphLeYsvyv4ADixM48dHiQsoPg-5gyWXS3pjS_V6tE42PZyy9BkRebKTA/s1600/A_Klumpp%2540252x200.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="252" data-original-width="200" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbcHuObneLSLZ1Xru2uKbI5nQrLg7FcFxWGQBcLUWVGYaCXVSQKJeKQssIK5CcvcxQDTlyNsHDTDwZc4JLxFWvphLeYsvyv4ADixM48dHiQsoPg-5gyWXS3pjS_V6tE42PZyy9BkRebKTA/s400/A_Klumpp%2540252x200.jpg" width="317" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Allan Klumpp</i></span></td></tr>
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Much of the detailed code of these programs was written by a team of specialists led by <b><i>Margaret Hamilton</i></b>. The task assignments to these individuals included, in addition to writing the code, the testing to certify that the program element met requirements. Overall testing of the assembled collection of program elements necessarily took the use of considerable human and machine resources. The programs had to be as near error-free as possible and any anomalies had to be understood and recorded for possible affect on the mission. Actually, no program errors were ever uncovered during the missions.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRnhIshQe7JNGWFreu_V5kiORdNw6veOCs39nlccL9Ouo6ZJXlSllpU24HMQ7dPg7pn2XDENbZnwMZuALAIjLANjZdo7esLtcre1vXAnUFLErWlfcvQOMf4V59NCH-B73jzt32cvIY5m1m/s1600/M_Hamilton_MIT.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="602" data-original-width="739" height="325" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRnhIshQe7JNGWFreu_V5kiORdNw6veOCs39nlccL9Ouo6ZJXlSllpU24HMQ7dPg7pn2XDENbZnwMZuALAIjLANjZdo7esLtcre1vXAnUFLErWlfcvQOMf4V59NCH-B73jzt32cvIY5m1m/s400/M_Hamilton_MIT.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Margaret Hamilton</i></span></td></tr>
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The highest level of testing was performed with a high fidelity digital simulation of the computer, spacecraft hardware, and mission environment. The creation, development, and maintenance of this simulator by Dr. Miller, <b><i>Keith Glick</i></b>, <b><i>Lance Drane</i></b>, and others included many diagnostic features essential to its effective use.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj01xYUv2tw9qIGE4y2qYSmKgx3fPkVSw5rxwrslqmfi7a4TI11XMm7Gu1mBzg0dOM5tave1a-KcjS2tc6U9-83ufkWwLI8AiR0MifXgUt6mSKTXvLF4DoWLt8CZ2QU1DS77laBjipwsDof/s1600/Keith_Click.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="373" data-original-width="320" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj01xYUv2tw9qIGE4y2qYSmKgx3fPkVSw5rxwrslqmfi7a4TI11XMm7Gu1mBzg0dOM5tave1a-KcjS2tc6U9-83ufkWwLI8AiR0MifXgUt6mSKTXvLF4DoWLt8CZ2QU1DS77laBjipwsDof/s400/Keith_Click.jpg" width="342" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>(Frederick) Keith Click</i></span></td></tr>
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Testing of the programs with the real hardware was done by Ain Laats in his systems test lab. Wide bandwidth aspects of the program were evaluated in a <b><i>digital/analog hybrid simulator</i></b> assembled by <b><i>Phillip Felleman</i></b> and <b><i>Thomas Fitzgibbon</i></b>.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2iP5Oixmy57BiUFBMfTOPul3lospUJ-4hvj55Mo0QKyNDkLyJO5JFcWFbePgFPnqC7R5RICFL1RNwHMsqe7pjyzOMoRKneFZghi5AI-BqUzily_YdrmjcXykvAt6MSZ2B4DOX_HjCy74m/s1600/HybridAnalog%2540302x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="302" data-original-width="380" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2iP5Oixmy57BiUFBMfTOPul3lospUJ-4hvj55Mo0QKyNDkLyJO5JFcWFbePgFPnqC7R5RICFL1RNwHMsqe7pjyzOMoRKneFZghi5AI-BqUzily_YdrmjcXykvAt6MSZ2B4DOX_HjCy74m/s400/HybridAnalog%2540302x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Beckman analog computer. Note the plug-boards used to program the device, and the strip-chart machine for plotting various parameters in real time.</i></span></td></tr>
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This hybrid simulator was also arranged to operate with the displays and controls of a pair of cockpit simulators to exercise crew functions in operating the Command Module and Lunar Module. These cockpit simulators were the responsibility of James Nevins assisted <b><i>Richard Metzinger</i></b>, <b><i>Ivan Johnson</i></b>, and others. The ill fated crew who died in the fire used this command module simulator in Cambridge for their training of what would have been the first manned Apollo flight. The use of the Cambridge facility was necessary because neither of the mission simulators at Houston or Cape Kennedy was ready.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgY1OII87MFdrWRBeW6IZF2-AqYt_l2jsU4-XGL1atd5GIOta2UJHYr6vPZgQDTtcYTaoYByTm0vr6WbeL_D4tEDYs_GD2ouMkN-GifLKlZA1MTo25MnMSKniN2hyQWhStUecAJMluJEp1F/s1600/HybridLMcockpit%2540297x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="297" data-original-width="380" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgY1OII87MFdrWRBeW6IZF2-AqYt_l2jsU4-XGL1atd5GIOta2UJHYr6vPZgQDTtcYTaoYByTm0vr6WbeL_D4tEDYs_GD2ouMkN-GifLKlZA1MTo25MnMSKniN2hyQWhStUecAJMluJEp1F/s400/HybridLMcockpit%2540297x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>LM cockpit on the third floor, directly above the hybrid lab. Console at left controlled the unsuccessful visual displays.</i></span></td></tr>
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<i><span style="color: #4c1130;">[Don Eyles - "The hybrid simulator was important because we could control a mission just as the astronauts would, using the computer's display and keyboard. At first we used the DSKY mounted on an equipment rack in the lab. Later we flew lunar landings from the LM cockpit — constructed from plywood but fully equipped with keyboard, eight-ball, displays, switches and control sticks — on the third floor directly above."]</span></i><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhebZMm4akfKg-kmRZGdpCgJTaZwsl21Lwt92KicdEO2E3ixKYT_vXbDTk5yhGvn5QEDW3UXMfRlwWA05QkZ65BVAhyOY8bYoqzXWVve0HDzF2IE5QyUzqkiUdJGx7BWlU6of2EmsGwTA6/s1600/HybridCoreRopeSim%2540302x380.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="302" data-original-width="380" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhebZMm4akfKg-kmRZGdpCgJTaZwsl21Lwt92KicdEO2E3ixKYT_vXbDTk5yhGvn5QEDW3UXMfRlwWA05QkZ65BVAhyOY8bYoqzXWVve0HDzF2IE5QyUzqkiUdJGx7BWlU6of2EmsGwTA6/s400/HybridCoreRopeSim%2540302x380.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Core rope emulator is in rack at right. The AGC itself is concealed in the next rack, which has a DSKY mounted on the front.</i></span></td></tr>
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The content of the flight computer software very clearly determined specific capabilities and procedures in conducting the Apollo mission. As stated earlier, the original philosophy underlying the guidance design was <b><i>onboard self sufficiency</i></b> of the astronauts in managing their mission. Early software was written with this crew-directed autonomy in mind, although it was based only intuitively on exactly how the crew would perform their tasks. The issue became clearer as the astronauts participated in the hardware and software design decisions and particularly on mock-up and simulator evaluations and the experience being gained in <b><i><a href="https://en.wikipedia.org/wiki/Project_Gemini" target="_blank">Gemini</a></i></b> flights.
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Initially the flight crew changed the software specifications so that they would participate step by step in the computer decisions during the mission phases. This necessarily made a heavy workload for the astronaut at the computer display and controls. As they gained more familiarity with the system and more confidence in it, the philosophy was modified to allow the computer to flow through the normal mission logic without the necessity for authorizing keystrokes from the operator. However, <b><i><u>the astronauts could watch, interrupt, and modify the functional flow if they so chose</u></i></b>.
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Another decision from the crew resulted in re-configuring details of the trajectories to be flown so that they could better monitor their progress and, if a failure occurred, they would be in an easier situation from which to take over with backup hardware and procedures. For example, the Lunar Module guidance was easily capable of injecting the vehicle on the ascent from the moon's surface onto a trajectory which would go directly to a rendezvous with the command module. However, the actual procedure used involved a number of more simple maneuvers called the <b><i>concentric flight plan</i></b> which had been used in Gemini rendezvous exercises.
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Gemini was flown for the last time late in 1966, and the attention of the astronauts and the ground controllers was put fully onto Apollo. By this time, however, the computer programs were already straining the memory capacity. The Flight Operations Division under <b><i><a href="https://en.wikipedia.org/wiki/Bill_Tindall" target="_blank">Howard W. Tindall</a></i></b> at Houston in March 1966, had taken over the management of the MIT software contract. One of Tindall's first actions was to hold a computer memory storage meeting with all involved parties to decide what computer capabilities should be in the limited program space.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuuEUqipwK5BzPThB2qWrG-JKXnqb-tVdbTuXX9q9unZNBNJhpI2BwBLH6Oy8XCivHILCc1jHqiEgvfI6LTj7LqMMl-ZsuHSXaBQ2K0NKmx4WNlySayDLWNa1K3pSu6Mkl1uaN-wfGLekZ/s1600/535868main_S73-31875_full.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1072" data-original-width="1600" height="267" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuuEUqipwK5BzPThB2qWrG-JKXnqb-tVdbTuXX9q9unZNBNJhpI2BwBLH6Oy8XCivHILCc1jHqiEgvfI6LTj7LqMMl-ZsuHSXaBQ2K0NKmx4WNlySayDLWNa1K3pSu6Mkl1uaN-wfGLekZ/s400/535868main_S73-31875_full.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>In MOCR at JSC from the left are Gary E. Coen, flight controller, directors Howard W. Tindall Jr., Dr. Christopher C. Kraft Jr., and Sigurd A. Sjoberg.</i></span></td></tr>
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This occurred on Friday the 13th of May and was thereby nicknamed <b><i>"black Friday"</i></b> by those whose favorite program elements were eliminated. Two more black Friday meetings were required and several <b><i>"tiger teams" </i></b>were assigned to keep the computer program within its bounds. An outcome was that some programs were eliminated that had provided the complete on-board self-sufficiency. The ground tracking facility and the Mission Control at Houston would be able to perform these functions and would, furthermore, relieve the astronauts of some of their work burden. Enough was left in the on-board computer programs, however, for the crew to rescue themselves and return to earth in case communications were lost.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig_TnrPtaYvKNGSC5_4qymj_UzZXcNi4G73luidHlcIjhag00o9fB7N1goeg2-D8auVor2eDchoef4Clt1EgC9gXkqfBsPkoWN0xv39duMV2uXy_pU2Jg1VdYLimc9wKS24IylGCzSYlwu/s1600/garman_3.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="698" data-original-width="956" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig_TnrPtaYvKNGSC5_4qymj_UzZXcNi4G73luidHlcIjhag00o9fB7N1goeg2-D8auVor2eDchoef4Clt1EgC9gXkqfBsPkoWN0xv39duMV2uXy_pU2Jg1VdYLimc9wKS24IylGCzSYlwu/s400/garman_3.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>AGC support room</i></span></td></tr>
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The management of the software effort, assigned at the time to <b><i>Edward Copps</i></b>, necessarily became far more structured. Tindall, supported by others from the Manned Spacecraft Center, held <b><i>monthly Software Development Plan Meetings</i></b> in Cambridge to watch progress and the allocation of resources to software tasks. After the programs were essentially complete but still subject to revisions, these meetings changed character to that of a <b><i>Software Control Board</i></b> held often-times in Houston. Even after that part of the code in the fixed memory for a given spacecraft was released for manufacture, desired program changes were identified. The logical similarity of fixed and erasable memory and the flexibility of executive and software designs did allow the prelaunch or in-flight loading of special programs into the erasable memory. This was done only under strict authorization of Tindall's software control board. <b><i><u>Many of these so-called erasable programs were used in flight to handle miscellaneous problems.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjRSPxCs0W7faDr_f_r3iR9_RSNpU1iljTEiGVsYRgFsJ-OEjD-K91HddMMSE9A8OcWdx3leBUfzOwv-62w_6g02j0pcdgPmM6l9TZI93YcUsnDhkx9od3pPCYEbaNXFKTR4lwWJnQ6b6p/s1600/Tindallgram_example__.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1230" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjRSPxCs0W7faDr_f_r3iR9_RSNpU1iljTEiGVsYRgFsJ-OEjD-K91HddMMSE9A8OcWdx3leBUfzOwv-62w_6g02j0pcdgPmM6l9TZI93YcUsnDhkx9od3pPCYEbaNXFKTR4lwWJnQ6b6p/s400/Tindallgram_example__.png" width="306" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Example "Tindallgram"</i></span></td></tr>
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During the later part of this period, Tindall also conducted in Houston what were called <b><i>Data Priority meetings</i></b>. These were held to establish the specific trajectory characteristics, operating timelines, and the interacting ground control and astronaut procedures under all normal and unusual conditions. The guidance hardware and particularly the computer programs in the memory influenced strongly the specific paths possible in conducting the mission.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJBtXSUszeQfConOUrGOJhqUUDtnAEW-VHMbGBGI1-GlHbmPqHLaVO7wh1cE9EBEv6VOPC0LZSkIt60Yx455OZsBBLPlcDwNA5HCA9XCn5flSMRq7OI2Hzn-vHU_8hBY80xOAdqNCfNeSG/s1600/Malcolm%252BJohnston.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="400" data-original-width="300" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJBtXSUszeQfConOUrGOJhqUUDtnAEW-VHMbGBGI1-GlHbmPqHLaVO7wh1cE9EBEv6VOPC0LZSkIt60Yx455OZsBBLPlcDwNA5HCA9XCn5flSMRq7OI2Hzn-vHU_8hBY80xOAdqNCfNeSG/s400/Malcolm%252BJohnston.jpg" width="300" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Malcolm Johnston, later years</i></span></td></tr>
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Accordingly the task was put onto <b><i>Malcolm Johnston</i></b>, at MIT, to search out the needed detailed design data available from the engineers in Cambridge for the Data Priority activity in Houston. It was the product of these meetings that finally tied together all mission operations with the guidance, navigation, and control.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLjQ6EK2se6CWS15rM0W-wwOH-BeS6xcvnk001Mi00HNxI3NKX7vnnkwM61AyMfAFA5DFAk5w2rLNZC-jEA9R5XhSVI5-lo1vhF99RQSRoBV-mfGLaDf7ix5SaiZyINPGakxJ3pAWJtsm-/s1600/February+24%252C+1970%252C+Russell+A.+Larson+and+David+G.+Hoag+.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="649" data-original-width="800" height="323" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLjQ6EK2se6CWS15rM0W-wwOH-BeS6xcvnk001Mi00HNxI3NKX7vnnkwM61AyMfAFA5DFAk5w2rLNZC-jEA9R5XhSVI5-lo1vhF99RQSRoBV-mfGLaDf7ix5SaiZyINPGakxJ3pAWJtsm-/s400/February+24%252C+1970%252C+Russell+A.+Larson+and+David+G.+Hoag+.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>February 24, 1970, Russell A. Larson (left) and David G. Hoag</i></span></td></tr>
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Crew training in these operations on the mission simulators required the detailed guidance system instructions provided tirelessly by <b><i>Russell Larson</i></b> working with the astronauts at Houston and Cape Kennedy."
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<b><span style="color: #0c343d;">Flight Experience /10/
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"The flight experience of the Apollo guidance system shows a remarkable consistency with expectation punctuated with outright surprises.
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The understanding of these surprises and recommending appropriate courses of action fell to a large part on the Instrumentation Laboratory teams in place at <b><i><a href="https://en.wikipedia.org/wiki/Charles_Stark_Draper_Laboratory#Locations" target="_blank">Houston</a></i></b>, <b><i><a href="https://en.wikipedia.org/wiki/Cape_Canaveral_Air_Force_Station" target="_blank">Cape Kennedy</a></i></b>, and <b><i><a href="https://en.wikipedia.org/wiki/Charles_Stark_Draper_Laboratory#Locations" target="_blank">Cambridge</a></i></b> providing guidance system mission support. During the quiet times of the flights, only about four Lab engineers would be on duty, but the number rose at times to several dozen performing special analyses, lab tests, and simulations. Leaders of this activity were Philip Felleman, Russell Larson, and <b><i>Stephen Copps</i></b> .
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<b><i>Apollo 3</i></b>, the first mission carrying the guidance system, which flew in August 1966. It was an unmanned, high energy, suborbital trajectory with four separate guidance controlled burns of the Service Module propulsion rocket. These were arranged such that the Command Module would enter the atmosphere with about 20% more specific energy than that in normal returns from the lunar missions. This was planned in order to <b><i><u>stress test the reentry heat shield</u></i></b>.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDLkWVDxIREkAXxWDnu7JMoT1dLuvOYAGpRcgsZVPlivlig3Mp2vteh5sHeBiZRN2XTAe1xkuWk0YkDdW2uJ9kDXVAqlGxCduTvLokz_1WKTXbHleHPAJ9VMK7inf9-361_dqtKzsAsTsd/s1600/Apollo_3_Launch_1966_apmisc-KSC-66PC-233.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="958" data-original-width="750" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhDLkWVDxIREkAXxWDnu7JMoT1dLuvOYAGpRcgsZVPlivlig3Mp2vteh5sHeBiZRN2XTAe1xkuWk0YkDdW2uJ9kDXVAqlGxCduTvLokz_1WKTXbHleHPAJ9VMK7inf9-361_dqtKzsAsTsd/s400/Apollo_3_Launch_1966_apmisc-KSC-66PC-233.jpg" width="312" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>August 25, 1966, Apollo Saturn 202 lifts off from launch pad 34.</i></span></td></tr>
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The landing east of Wake Island about <b><i>350 kilometers short</i></b> of the intended target was due to an unanticipated error in the aerodynamic model of the Command Module.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK1p8MVDTscP1LvJOIduV05Kl_LFtp1H6gFzWomsqLGxY8WZP_RyvTUNR8kApKnDMWkiqNdpeGT1BQYHC8jetqsNpNT73t-wQ375xPURPU4qJANvV4APteGbLn2D9epKAsZAdiDFWQZUe7/s1600/Apollo_3_CM_apmisc-S66-49413.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="815" data-original-width="800" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhK1p8MVDTscP1LvJOIduV05Kl_LFtp1H6gFzWomsqLGxY8WZP_RyvTUNR8kApKnDMWkiqNdpeGT1BQYHC8jetqsNpNT73t-wQ375xPURPU4qJANvV4APteGbLn2D9epKAsZAdiDFWQZUe7/s400/Apollo_3_CM_apmisc-S66-49413.jpg" width="392" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo spacecraft 011 Command Module floats in the Pacific Ocean during recovery operations following the successful unmanned Apollo/Saturn Mission 202 test flight, August 25, 1966</i></span></td></tr>
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The actual lift available was enough lower than design intent so that even though the guidance commanded full upwards lift, the vehicle dropped into the ocean early, The guidance indicated splash point was within 18 kilometers of the Navy's reported retrieval point-this after an hour and a half of uncorrected all inertial navigation through high acceleration maneuvers.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjn9hTZ_nq0kpJYdKVGofZpjpdh1ilamC6_l_7uKRGZQ8cahm3LdbA-T-PoOsIgAtZcslAE1ebYX6m0BXgbVJytxl6d1Cffx_5p9t-dGGkV-yyK1J4wtBFD_Iz24-OeC-BEPVG-bRoHz6z0/s1600/Apollo_4_ap4-67-HC-542.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="571" data-original-width="900" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjn9hTZ_nq0kpJYdKVGofZpjpdh1ilamC6_l_7uKRGZQ8cahm3LdbA-T-PoOsIgAtZcslAE1ebYX6m0BXgbVJytxl6d1Cffx_5p9t-dGGkV-yyK1J4wtBFD_Iz24-OeC-BEPVG-bRoHz6z0/s400/Apollo_4_ap4-67-HC-542.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>A KSC officer stands by as Apollo 4 rolls out of the VAB, August 26, 1967</i></span></td></tr>
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<b><i>Apollo 4</i></b>, November 1967, also unmanned was guided into a high apogee trajectory after two earth orbits and was to be given an extra rocket burn on the way down to simulate the lunar return velocity. However, in this automatic maneuver, a ground controller in Australia, confused by a delay in telemetry, sent an engine turn-on signal from the ground just after it had already been initiated automatically by the guidance system. This action transferred rocket cutoff responsibility away from the onboard system.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitmkPi7zKgOcVmbgXxia0BZO6pR_fvNLhf_565XYg5STeN3Hejq9RbmTGP78Amvy6vlMyqn4Mfs962bRwayjdTZY_ZLNANbCn34V3_Odz2jlFUlXOLgRfWAOy9WqhMaSRlkJHzHnZQOe5b/s1600/Apollo_4_CM_ap4-S67-49420HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1410" data-original-width="1422" height="396" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEitmkPi7zKgOcVmbgXxia0BZO6pR_fvNLhf_565XYg5STeN3Hejq9RbmTGP78Amvy6vlMyqn4Mfs962bRwayjdTZY_ZLNANbCn34V3_Odz2jlFUlXOLgRfWAOy9WqhMaSRlkJHzHnZQOe5b/s400/Apollo_4_CM_ap4-S67-49420HR.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The Apollo 4 Spacecraft 017 Command Module, with flotation collar attached, is prepared for hoisting aboard the U.S.S. Bennington during recovery operations in the Mid-Pacific, November 9, 1967</i></span></td></tr>
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The ground controller sent the <b><i><u>cutoff signal 13.5 seconds later than required</u></i></b> for the planned entry test conditions. It was, therefore, a severe entry test for both the heat shield and the guidance system. The latter controlled the entry into a range stretching skip out of the atmosphere and a reentry back into it with a splash in the ocean 3.5 kilometers different from the point intended as indicated by extrapolated ground tracking data.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkU0Xsef9CVYk_-cp7s3oENtkoYAzaRAbYkTZy1HiaAmzsYCnLJ1u1uVBV_hAzY_KpKJnsYq4pSDZUg61SiUKJ50_ygaU0Nk_BOfwk-OTDzszg6r4bc3pyBTvhuW50AW4bb4eqtx0od0SI/s1600/ap5-S67-50927HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1470" data-original-width="1173" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkU0Xsef9CVYk_-cp7s3oENtkoYAzaRAbYkTZy1HiaAmzsYCnLJ1u1uVBV_hAzY_KpKJnsYq4pSDZUg61SiUKJ50_ygaU0Nk_BOfwk-OTDzszg6r4bc3pyBTvhuW50AW4bb4eqtx0od0SI/s400/ap5-S67-50927HR.jpg" width="318" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 5, mating of Lunar Module-1 with Spacecraft Lunar Module Adapter-7, November 22, 1967</i></span></td></tr>
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<b><i>Apollo 5</i></b>, in earth orbit in January of 1968, was the only unmanned test with the Lunar Module. The mission went as planned until the time of the first guidance controlled Lunar Module rocket burn. The system initiated ignition as planned and using the approved model for thrust buildup looked for the acceleration to rise as expected. A change in the rocket pressurization, not recognized by the software, delayed the thrust buildup longer than accepted by a safety criterion built into the computer program.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZTI60TvSW2A-X_w0CDcZPZxgbPR4Mn2HOREV3g1Za19LoQ7PMpVJdKyXVY000ZWN-TKyIhCNeCl7MTm1xtoANCXQfcWbj1gFz9CVdvGJZ9MJdgSRxK_qERinD6rDridaoNzdxmUCyIN_v/s1600/ap5-S68-19456.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1014" data-original-width="802" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZTI60TvSW2A-X_w0CDcZPZxgbPR4Mn2HOREV3g1Za19LoQ7PMpVJdKyXVY000ZWN-TKyIhCNeCl7MTm1xtoANCXQfcWbj1gFz9CVdvGJZ9MJdgSRxK_qERinD6rDridaoNzdxmUCyIN_v/s400/ap5-S68-19456.jpg" width="316" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Early evening launch of Apollo 5 from pad 37B - an unmanned lunar module test flight, January 22, 1968</i></span></td></tr>
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The system, as designed, then <b><i>immediately signaled shutoff</i></b>. As a result, since the problem was not immediately understood, the remaining rocket burns were <b><i><u>controlled by a simple backup system</u></i></b>. All primary mission objectives were met.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVQwBZ-_omrsyxXZasO-rBS7nPL5U1AihVRvkwmHnGIxLxhueO00ihCBeesLqIfk7aXf4VNz2k2svzHa5ACqYD1pq5EYZptS_sdAYEOPpQIMFHXVLfjuvLlh6bt-Uq8ScO8xKZAQ-reQ5L/s1600/ap6-68-HC-191HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1300" data-original-width="1452" height="357" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVQwBZ-_omrsyxXZasO-rBS7nPL5U1AihVRvkwmHnGIxLxhueO00ihCBeesLqIfk7aXf4VNz2k2svzHa5ACqYD1pq5EYZptS_sdAYEOPpQIMFHXVLfjuvLlh6bt-Uq8ScO8xKZAQ-reQ5L/s400/ap6-68-HC-191HR.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 6 - the S-IC/S-II interstage falls away as photographed from a camera on the second stage that would soon detach and parachute into the Atlantic, April 4, 1968</i></span></td></tr>
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<b><i>Apollo 6</i></b> in April 1968, had a mission similar to Apollo 4, but unfortunately the Saturn booster <b><i><u>third stage could not be restarted</u></i></b> for the lunar trajectory injection simulation burn. Consequently, the spacecraft Service Module was used for this under guidance system control. Since the resulting burn was necessarily very long as targeted, too little fuel for the maneuver needed to drive the spacecraft back into the atmosphere at lunar return velocity was left. The lower velocity was not enough specific energy for the guidance to steer the vehicle's lift to the planned target, and it fell short by almost 100 kilometers with the guidance indicating a splash within 4 kilometers of that later reported by the recovery force.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLuo1M8BGsoctwMF1xDumMtbUcYKaeJJbV4QT9_IZEzNbTUQ2rIWhSHzj0YSdLxn4BhJ-nqE4fJFfl_SUHcos4PihS8aZsJhhpUeODuJEB6U20ORh5RDxuPbOC4dxEwm7NGTneX3TT0vj1/s1600/ap7-67-H-774.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="925" data-original-width="732" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiLuo1M8BGsoctwMF1xDumMtbUcYKaeJJbV4QT9_IZEzNbTUQ2rIWhSHzj0YSdLxn4BhJ-nqE4fJFfl_SUHcos4PihS8aZsJhhpUeODuJEB6U20ORh5RDxuPbOC4dxEwm7NGTneX3TT0vj1/s400/ap7-67-H-774.jpg" width="316" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 7, the flight and back-up crews for NASA's first manned Apollo Block II spaceflight at a press conference and design review meeting at the North American plant., May 10, 1967</i></span></td></tr>
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<b><i>Apollo 7, the first manned flight</i></b>, October 1967, exercised a rendezvous with the spent third stage of the Saturn booster from about 100 miles separation. The sextant was used by astronaut <b><i>Don Eisele</i></b> to give the computer direction information referenced to the stellar aligned inertial system. No ranging data were available as the equipment was not yet available.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWqKIG74OzhVGE14vKH8ZH7F3I4BM3Riv-cnKcPj68C5EtEllpyv4W_1R0ajDEzpq1OLU8erbabZSoMiRpaB79UH385hAxthIyaJ0H2CRRXJI-iesq2K04hWirmYw9s2JKiDgVJoQpib9z/s1600/ap7-68-H-730.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="732" data-original-width="925" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhWqKIG74OzhVGE14vKH8ZH7F3I4BM3Riv-cnKcPj68C5EtEllpyv4W_1R0ajDEzpq1OLU8erbabZSoMiRpaB79UH385hAxthIyaJ0H2CRRXJI-iesq2K04hWirmYw9s2JKiDgVJoQpib9z/s320/ap7-68-H-730.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The backup crew for Apollo 7 (l-r) Astronauts Eugene A. Cernan, John W. Young, and Thomas P. Stafford, after completing egress training at Calveston Bay, TX., August 6, 1968</i></span></td></tr>
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Nevertheless, the computer converged upon a good rendezvous solution. Three times during the flight untested procedures used by the crew caused the computer to <b><i>"restart"</i></b> successfully. Restart was a software feature provided in all problems to protect against data loss and provide instant recovery from logically improper activity. Many times in future flights, restart accommodated safety to computer logic and operational problems.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJ9Ot5_iT85LGa_i3HkeZXMnuKi8yO1jS9E7LeMlQ9h49ae-apPjtiJHA_6aAL2li9HfrAveXFBShT3LW0i74bRDDVI45r_p8zxeK6EBAe6ZKkR0SYDFx8GNQQetZ-HHGRbb9nFnrXYXwJ/s1600/s-l500.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="407" data-original-width="500" height="325" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJ9Ot5_iT85LGa_i3HkeZXMnuKi8yO1jS9E7LeMlQ9h49ae-apPjtiJHA_6aAL2li9HfrAveXFBShT3LW0i74bRDDVI45r_p8zxeK6EBAe6ZKkR0SYDFx8GNQQetZ-HHGRbb9nFnrXYXwJ/s400/s-l500.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo 8 astronaut James A. Lovell</i></span></td></tr>
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<b><i>Apollo 8</i></b> with the first men to orbit the moon, December 1968, was a fantastic success of man and machine. All of the guidance features in the Cormnand Module were exercised with few problems. In the very first application of on-board autonomous navigation in space, <b><i>Jim Lovell</i></b> made over 200 sextant sightings on the way out to the moon. His computer solution of the nearest approach to the backside of the moon agreed within 2.5 kilometers of that later reconstructed from ground tracking data.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpO8IOFvgfu71JM7e5nE_TcW8NCLMG4xfKSiN6vj5yv9ae4QESxXwwWH6vmyNqewwg4EGqoMo1iye-bCtxOgZhV0FrhklP0F9g2Z6ZIrhXdYzjL858OU-7HcYNQ9Bvv1mRR76sBvbTEHTV/s1600/ap8-68-H-1306.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="635" data-original-width="945" height="268" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpO8IOFvgfu71JM7e5nE_TcW8NCLMG4xfKSiN6vj5yv9ae4QESxXwwWH6vmyNqewwg4EGqoMo1iye-bCtxOgZhV0FrhklP0F9g2Z6ZIrhXdYzjL858OU-7HcYNQ9Bvv1mRR76sBvbTEHTV/s400/ap8-68-H-1306.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Two of the three Apollo 8 astronauts, Frank Borman, on steps, and William Anders, entering mission simulator at KSC, December 17, 1968</i></span></td></tr>
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The critical <b><i>return-to-earth maneuver</i></b>, Christmas morning, was so accurate that only a single 1.5 meter/sec midcourse maneuver was required 5 hours later. Lovell's transearth navigation with the sextant indicated approach to the entry corridor within 30% of the normal tolerance. By this <b><i>he showed that he could have returned safely without the help of the ground control</i></b>. At one point early in the return, Lovell, thinking he was telling the computer that he was using star number 01, actually punched in the command for the computer to go to the earth prelaunch program 01. This caused all sorts of mischief including the loss of the inertial system alignment. He had no problem getting all this quickly and properly rearranged.
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The lunar module awaits extraction from Apollo 9's S-IVB stage</i></span></td></tr>
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<b><i>Apollo 9</i></b>, which flew a very complex mission in March 1969, exercised almost all functions of the Lunar Module guidance in earth orbit including the rendezvous with the Command Module. The only in flight guidance hardware failure in the program occurred early in the mission. <b><i><u>A tiny pin got dislodged from the scanning telescope angle counter display rendering the counter useless.</u></i></b> The counter, however, was only a backup to the normal readout of the computer display, so fortunately the problem had no impact on the mission.<br />
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Dave Scott aboard Apollo 9</i></span></td></tr>
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At one point, <b><i>Dave Scott</i></b> loaded the celestial coordinates of Jupiter into the computer and asked it to point the optics at the planet. He was rewarded with a fine display of Jupiter and her moons in the 28 power instrument.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGNeXBqqxaO659iR1DptBtrWVlnLsitfavyDqVuKCezp8cNWhat2rYLZ1QgHQNqFwMy9BcrFG1hs0xIpnepa74mO9sNk7cvrO5xSz_urU2jpRyEua3_HXEwiakrwJPDcQwdmDGRO9JLpmZ/s1600/Jupiter_and_Moons.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="700" data-original-width="991" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGNeXBqqxaO659iR1DptBtrWVlnLsitfavyDqVuKCezp8cNWhat2rYLZ1QgHQNqFwMy9BcrFG1hs0xIpnepa74mO9sNk7cvrO5xSz_urU2jpRyEua3_HXEwiakrwJPDcQwdmDGRO9JLpmZ/s400/Jupiter_and_Moons.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Jupiter and moons</i></span></td></tr>
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Later, he loaded the computer with the orbital parameters of the Lunar Module which had by then been abandoned and sent away into a high orbit. There it was in the eyepiece 5,000 kilometers away.
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 10, view of lunar farside showing an area in the vicinity of IAU Crater No. 300, May 18, 1969</i></span></td></tr>
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<b><i>Apollo 10</i></b> in May 1969, was a complete lunar mission, except the actual touchdown on the moon was by-passed as planned. All guidance functions were uneventful except that a new technique was developed during the flight to put the vehicle into a <b><i>stable rotation of 3 revolutions per hour</i></b> during the long coast to the moon. This spin was used earlier in Apollo 8 to keep the thermal loads on the skin from the sun equalized, but on that mission occasional firings of the attitude jets were necessary to hold the spin as required. Besides wasting fuel, the noise of these firings disturbed the crew's sleep.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqa2Wi34oDriCykVndNE0gp33qtzHp8q56vDX0eAQI9hfA2z-5pTjgMftg691gM2m4V3X75fpodjAdx6k4U92DGFXuXE-4MbfSp2uGElT00m3DdyUcrFX34KwAHWXA6mh8YILTOGSU1Qnh/s1600/ap10-KSC-69P-348HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="915" data-original-width="1416" height="257" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiqa2Wi34oDriCykVndNE0gp33qtzHp8q56vDX0eAQI9hfA2z-5pTjgMftg691gM2m4V3X75fpodjAdx6k4U92DGFXuXE-4MbfSp2uGElT00m3DdyUcrFX34KwAHWXA6mh8YILTOGSU1Qnh/s400/ap10-KSC-69P-348HR.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The Apollo 10 crew shares a laugh with Vice President Agnew, seen holding mission mascot Snoopy, May 17, 1969</i></span></td></tr>
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During Apollo 10, <b><i>Joseph Turnbull</i></b>, in MIT Cambridge, exercised various methods on a simulator for initiating the spin so that the residual fluid motions in all the fuel tanks would not later on destabilize the spacecraft motions. His procedures were radioed to the crew via Mission Control in Houston; on the second try it worked and stability was achieved <b><i>without further thruster activity</i></b>.
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 11 Command Module Pilot Michael Collins in Command Module simulator during simulated rendezvous and docking maneuver. June 19, 1969</i></span></td></tr>
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<b><i>Apollo 11</i></b>. Finally on July 20 and 21, 1969, Apollo astronauts first walked on the "magnificent desolation" of the moon's surface. The actual landing was particularly exciting, however, due to <b><i><u>alarms in the computer during the descent</u></i></b>. These alarms were caused by an erroneous mode switch position resulting in maximum pulse rate signals being sent to the computer from the rendezvous radar, which was, of course, not needed during the landing. The computer, already operating near capacity, was overloaded by these extraneous inputs causing it to restart and display the alarms.
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<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Astronaut Neil Armstrong</i></span></td></tr>
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<i><span style="color: #274e13;">YouTube video:</span></i> <b><i><a href="https://youtu.be/RONIax0_1ec" target="_blank">"Apollo 11 landing from PDI to Touchdown"</a></i></b><br />
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The ground controllers and <b><i>Neil Armstrong</i></b> were on top of the problem. They knew well that the computer, in restarting, would keep the essential programs running for the landing.<br />
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Armstrong's first photo after setting foot on the Moon, July 20, 1969</i></span></td></tr>
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However, Armstrong's attention was diverted during the time he should have been using the window display which would indicate to him what the lunar surface was like at the point where the guidance system was bringing him. When he finally looked, it was a young ray crater strewn with large rocks. It was too late to re target the computer for the more efficient trajectory change to a more suitable point. Instead, he selected a semiautomatic altitude hold mode and maneuvered across the crater to a landing at <b><i>"Tranquility Base"</i></b>.
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgD7Ut-d7AQ3YHlWXDPm6JTidfxE5Z7p_Zgnt0ntMGnY2LIzy5kedIUj7YOZTYxrXu82IeydchsAUpBj38G43DIThatshQCr5_FD-cZOM2_-N4GbcbH7hyrkXX4fjzFP1SyfzsiRygOJ19-/s1600/ap12-S69-60068.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="546" data-original-width="750" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgD7Ut-d7AQ3YHlWXDPm6JTidfxE5Z7p_Zgnt0ntMGnY2LIzy5kedIUj7YOZTYxrXu82IeydchsAUpBj38G43DIThatshQCr5_FD-cZOM2_-N4GbcbH7hyrkXX4fjzFP1SyfzsiRygOJ19-/s400/ap12-S69-60068.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 12, shortly after liftoff, lightning struck both the Saturn V and the launch tower</i></span><span style="color: #cc0000; font-size: small;"><i>. November 14, 1969</i></span></td></tr>
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<i><span style="color: #274e13;">YouTube video:</span></i> <b><i><a href="https://youtu.be/BmkDRMcjols" target="_blank">"Apollo 11's Michael Collins visits MIT/AeroAstro April 1, 2015"</a></i></b><br />
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<b><i>Apollo 12</i></b> in November 1969, was <b><i><u>hit by two lightning strikes</u></i></b> early in the boost to earth orbit. The large current pulses, passing through the innards of the command module surrounded by the insulating heat shield, caused power transients which forced the computer to restart both times. Although the computer did not lose any memory, the interface circuits to the inertial system were affected transiently and <b><i>Pete Conrad</i></b> reported a tumbling inertial platform.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiM1O8bXbRuKEj8nLDsjwO-DTCYGgBIxdJxjRVgWN99Cj61s95D0PfB5H1O2LbURZJd-C_KNFay_z-NaGVQ_vDQI3LppcNcZQENEPF-5S2s_vOdmpa9UnNfu213lH_tXcFOmy3pqVuUOJU/s1600/ap12-69-H-1763HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1267" data-original-width="1600" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhiM1O8bXbRuKEj8nLDsjwO-DTCYGgBIxdJxjRVgWN99Cj61s95D0PfB5H1O2LbURZJd-C_KNFay_z-NaGVQ_vDQI3LppcNcZQENEPF-5S2s_vOdmpa9UnNfu213lH_tXcFOmy3pqVuUOJU/s400/ap12-69-H-1763HR.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 12 astronauts Gordon (left), Bean and Conrad, during lunar debriefing aboard Hornet, November 26, 1969</i></span></td></tr>
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Fortunately, the <b><i>Saturn booster guidance system, further distant from the current pulse, was not disturbed and completed its normal function</i></b>. The crew was able to realign the inertial system to the star s while in earth orbit, and continue the mission. They landed on the moon on the edge of the small crater in which had sat the unmanned Surveyor spacecraft since its arrival two and a half years earlier.
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 13, view of the crippled Service Module after separation.</i></span></td></tr>
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<b><i>Apollo 13</i></b>, the emergency and rescue of the crew in April 1970, after the <b><i><u>explosion and loss of oxygen and power in the Service Module</u></i></b>, urgently depended upon a quick maneuver to get back on an earth's return trajectory using the only propulsion available, that of the Lunar Module. The Lunar Module Autopilot was not designed to push the heavy Command and Service Module through the limber docking joint as a normal control mode.
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<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>"Software saved Apollo 13" - almost every possible mishap had been foreseen</i></span></td></tr>
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However, <b><i><u>for just a contingency such as this, the necessary software had been developed by the Instrumentation Laboratory</u></i></b> and was included in the computer program; but it was very little tested. The critical maneuver was accomplished with stable control. Without Service Module power and in order to conserve the limited life Command Module batteries for the entry, the guidance system there was shutdown completely. After three days of cold, rough treatment for the precision instrument, would the inertial system get reheated without harm, get started and aligned, and retain its calibration for it use in guiding entry? <b><i>The entry proceeded normally</i></b> and splash in the ocean was indicated within one kilometer of the target.
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<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Wide angle view of Mission Control Center during Apollo 14 transmission, January 31, 1971</i></span></td></tr>
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<b><i>Apollo 14</i></b>, the February 1971 mission was normal for the guidance system until about three and a half hours before the scheduled powered descent onto the moon. At this time the Lunar Module computer started receiving intermittent <b><i><u>faulty signals from the main panel abort button</u></i></b>, which, if they occurred during the descent to the moon, would irrevocably start the abort sequence sending the vehicle back into orbit.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwXXEaEsENDeFpp1NFzdFQr8-Udnk0BQ7ShM5ZBchFR_hXlpru3zKXXu3yKoXEPxok8Tj1nfp3PRvSJxTbpa73vJhDfKPaA5YD-AUxAJSVXKb6s2VQTPpXOhChAYB1ihp4N2A1B2KpCVnD/s1600/Apollo_LM_Abort_Button.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1401" data-original-width="1407" height="318" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgwXXEaEsENDeFpp1NFzdFQr8-Udnk0BQ7ShM5ZBchFR_hXlpru3zKXXu3yKoXEPxok8Tj1nfp3PRvSJxTbpa73vJhDfKPaA5YD-AUxAJSVXKb6s2VQTPpXOhChAYB1ihp4N2A1B2KpCVnD/s320/Apollo_LM_Abort_Button.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Lunar Module abort button</i></span></td></tr>
</tbody></table>
<br />
As in every mission, the Instrumentation Laboratory (Actually, a year earlier, the Instrumentation Laboratory had been renamed The Charles Stark Draper Laboratory in honor of its founder.) <b><i>support engineers</i></b> in Houston, Cape Kennedy, and Cambridge were monitoring progress and immediately started working on a way of preventing the mission from being terminated needlessly.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja2kEH5rFEpB-MRUG98OqJMXW8MQ0uTJmcledNlHIuTApTVOUjH7oPcVr6vJiZP-ZKrDTz9j3tVKLGwIP3jTBcMEZt3jiPfENv3TAViKz_h7znrBnq8EKdAbtvjlF3_ywUSLyncxf8mxRE/s1600/donanddoc.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1153" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEja2kEH5rFEpB-MRUG98OqJMXW8MQ0uTJmcledNlHIuTApTVOUjH7oPcVr6vJiZP-ZKrDTz9j3tVKLGwIP3jTBcMEZt3jiPfENv3TAViKz_h7znrBnq8EKdAbtvjlF3_ywUSLyncxf8mxRE/s400/donanddoc.jpg" width="287" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Don Eyles (left) with Draper</i></span></td></tr>
</tbody></table>
<br />
Among the various ideas proposed, one suggested by a young engineer, <b><i>Donald Eyles</i></b>, was selected and after hurriedly being <b><i>tested on the simulators in Cambridge</i></b> was sent over the circuits to the Mission Control Center in Houston for their evaluation. This procedure, which was sent up to the crew as soon as they came around from the back of the moon, involved four sets of computer input keystrokes to be made on-board at appropriate times in the descent. The First of these would fool the necessary part of the computer logic into thinking that it was already in an abort mode while the landing programs, nevertheless, would continue to bring the vehicle down to the lunar surface. The astronauts had only 10 minutes after receiving this computer reprogramming procedure before they had to start their descent. They accepted it: and the <b><i>landing went flawlessly</i></b>, exactly to the planned spot on the moon.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Hu1SkiZzWx6eLgY3BY5oROrQpLrN0mm6Sfn8OEfT5Zo6oPCJRC6r1jM8nIRbKBzAJcHT5mf1_V-qc2RJnVL2rbRHcuzVAy4Ttih9UgMGCVJmK54clTCQote5ACyFc1DLXqz7OB4-3tJO/s1600/AS16-113-18340HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1581" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Hu1SkiZzWx6eLgY3BY5oROrQpLrN0mm6Sfn8OEfT5Zo6oPCJRC6r1jM8nIRbKBzAJcHT5mf1_V-qc2RJnVL2rbRHcuzVAy4Ttih9UgMGCVJmK54clTCQote5ACyFc1DLXqz7OB4-3tJO/s400/AS16-113-18340HR.jpg" width="395" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Apollo 16 Commander John Young jumps and salutes the flag, April 20, 1972</i></span></td></tr>
</tbody></table>
<br />
<b><i>Apollo 15</i></b>, <b><i>Apollo 16</i></b> and <b><i>Apollo 17</i></b>, there were three more lunar landing missions.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNMYqyILnsyt31H-5kVzPzQ2qei0jgh27gab25EdfH3HoxNNv3SpvrsJ5cSkYyl_h__Bx3eecW1RHHh5zeaf_0WATYhh9LF4ahTMJjYT9PJquHfFknfyEwhuedhuXhv-tIJIVEDbcuHI9_/s1600/SL4-150-5080.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="802" data-original-width="530" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNMYqyILnsyt31H-5kVzPzQ2qei0jgh27gab25EdfH3HoxNNv3SpvrsJ5cSkYyl_h__Bx3eecW1RHHh5zeaf_0WATYhh9LF4ahTMJjYT9PJquHfFknfyEwhuedhuXhv-tIJIVEDbcuHI9_/s400/SL4-150-5080.jpg" width="263" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Astronauts Carr and Pogue demonstrate weight training in zero-gravity, 1974</i></span></td></tr>
</tbody></table>
<br />
<b><i>Skylab 2</i></b>, <b><i>Skylab 3</i></b> and <b><i>Skylab 4</i></b>, there were three earth orbital visits to the Skylab.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9xN1mnUby2owPYdxCJ1rcZyGZfhNy2wO2TsFHqAwcy7JX0K9nOrQ4xcCaIjFtbqrVzLHVVjd-2oTjrRBJNggn-UGuNrCYZZcRhPFWzfRtO60yyfSQYqgHmrvCi5iLMgIh-YbAX8JA345r/s1600/AST-32-2686.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="538" data-original-width="633" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9xN1mnUby2owPYdxCJ1rcZyGZfhNy2wO2TsFHqAwcy7JX0K9nOrQ4xcCaIjFtbqrVzLHVVjd-2oTjrRBJNggn-UGuNrCYZZcRhPFWzfRtO60yyfSQYqgHmrvCi5iLMgIh-YbAX8JA345r/s400/AST-32-2686.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>View from Soyuz of Apollo CSM with docking adapter, 1975</i></span></td></tr>
</tbody></table>
<br />
<b><i>Apollo–Soyuz Test Project (ASTP)</i></b>, the rendezvous with the Soviet cosmonauts in Soyuz.<br />
<br />
<br />
Although the Apollo guidance, navigation, and control system continued to get involved in the unexpected, any further account would be anticlimactic to the dramatic saving of the Apollo 14 and its objective the landing of men on the moon."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG-FM5oUsHI1r6xOlU3ym8iRxo-28GFxkUlsynyFKav0u9x0bZUHJ5dKxrk19E1sWme8lqwb9urirmTE42OZu9dEX4xpC6eNnBNvo5043ehvVSepDou-Ay7RA-eKdnp0Y-BPO2kKqngeKO/s1600/mg-S62-2704HR.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="925" data-original-width="1600" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjG-FM5oUsHI1r6xOlU3ym8iRxo-28GFxkUlsynyFKav0u9x0bZUHJ5dKxrk19E1sWme8lqwb9urirmTE42OZu9dEX4xpC6eNnBNvo5043ehvVSepDou-Ay7RA-eKdnp0Y-BPO2kKqngeKO/s400/mg-S62-2704HR.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>The original seven astronauts pose with an Atlas model, July 12, 1962</i></span></td></tr>
</tbody></table>
<br />
<h4>
Apollo contributions remembered 1995 /11/</h4>
Several veterans of MIT's work on the Apollo project were recognized for their accomplishments and reminisced about their ground-breaking work at a luncheon last Monday, Nov. 20, 1995.<br />
<br />
On hand to receive certificates of appreciation as members of the MIT Apollo Honor Roll were</div>
<div>
<ul>
<li>Richard Battin</li>
<li>Joseph G. Gavin Jr.</li>
<li>David G. Hoag</li>
<li>James S. Miller</li>
<li>John Miller</li>
<li>Robert Seamans</li>
<li>William Widnall</li>
<li>Buzz Aldrin</li>
<li>Philip Chapman</li>
<li>Charles Duke</li>
<li>Edgar Mitchell</li>
<li>Russell Schweickart</li>
<li>David Scott</li>
</ul>
During the Apollo project, the honorees were associated with the MIT Instrumentation Laboratory, now the Charles Stark Draper Laboratory, Inc. (The late Institute Professor Emeritus, who founded the laboratory, was a pioneer in instrumentation and a member of the faculty for more than 30 years. He retired in 1967 and died in 1987.)<br />
<br />
Dr. Draper was "an absolutely extraordinary person who touched all of us who worked with him in different ways," Dr. Young said. The massive and ultimately successful effort to put a man on the moon "represented a pinnacle of American technology that excited the imaginations of not just those of us that worked on it, but the entire world's," he added.<br />
<br />
Dr. Seamans, former associate and deputy director of NASA who was in Mission Control at the time of the Apollo 11 moon landing, had "an enormous influence on making the very existence of the Apollo program a reality," Dr. Young said. Dr. Seamans recalled some proposals of varying feasibility that were discussed for the space effort, including an idea for launching Saturn stages from dirigibles. The space effort got its first major push early in the Kennedy administration when Soviet cosmonaut Yuri Gagarin went into orbit, "and Washington, DC, also went into orbit," he quipped.<br />
<br />
When Grumman Corp. was awarded the contract for the lunar module, "we really didn't know what we were getting into," recalled Mr. Gavin, former Grumman president and chief operating officer who was vice president and director of the lunar module program. Reliability-achieved by taking nothing for granted and "turning over every stone on the beach"-was a paramount goal, he said. For example, just to be thorough, an engineer disassembled some historically reliable switches slated for use in space and discovered that many had loose bits of solder inside that could cause failure in zero gravity. "It was that kind of responsibility, curiosity and attention that made the difference," said Mr. Gavin, a Life Member of the Corporation.<br />
<br />
Dr. Battin designed the algorithms for various mission phases and programmed guidance computers on board the Apollo command module and lunar excursion module. His students at MIT included Buzz Aldrin, one of the first to walk on the moon, as well as two other moon-mission astronauts.<br />
<br />
At the Instrumentation Lab, David Hoag was technical director and later program manager for MIT's Apollo role. One of the problems he worked to resolve was "gimbal lock," in which rocket gimbals (one of which he brought to the luncheon for demonstration) would freeze up in certain spacecraft orientations.<br />
<br />
John Miller, retired president and CEO of Intermetrics, Inc., and current aero/astro research affiliate, was a technical director for the guidance, navigation and control system at the Instrumentation Lab, which he joined in 1959. He and his colleagues followed a dictum that "there would be no unexplained failures," he said. "We learned more about the systems and where things went wrong and needed fixing by never having failures unexplained."<br />
<br />
Dr. James Miller (ScD '61) led the team that developed a full-scale simulation of the Apollo spacecraft, guidance computer and navigation system for testing the on-board computer's flight software. The vast effort by everyone involved in the Apollo project "seemed to bring out the best in every one of them," he said. "A lot of people worked very hard."<br />
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<div class="separator" style="clear: both; text-align: center;">
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigaKJaE6xBOCI-xZyW8CqfmdsmAu3jOSl-kgImjOZJDTPM3EZHmoDI5085GBUuecrNPhQPhk86FMpceXW7ZUiskLA4E7uCe3RXsOWQ_A4Daaf0Luh_e9mrqheqNhepVj2ajUH0E1JKuzo2/s1600/grumman_support.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="350" data-original-width="515" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigaKJaE6xBOCI-xZyW8CqfmdsmAu3jOSl-kgImjOZJDTPM3EZHmoDI5085GBUuecrNPhQPhk86FMpceXW7ZUiskLA4E7uCe3RXsOWQ_A4Daaf0Luh_e9mrqheqNhepVj2ajUH0E1JKuzo2/s400/grumman_support.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>There was lot of support people in MCC Houston during Apollo missions, not just the mission control team. This is a picture from the MCC Vehicles Staff Support Room during Apollo 10, with the Grumman Flight Control Support Team in it.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">REFERENCES</span></b><br />
<br />
1. A Recoverable Interplanetary Space Probe, Report R-235, MIT Instrumentation Laboratory, July 1959.
<br />
<br />
2. Interplanetary Navigation System Study, Report R-273, MIT Instrumentation Laboratory, April 1960.
<br />
<br />
3. Hoag, D.G., The Navigation Guidance, and Control of a Manned Lunar Mission, MIT Instrumentation Laboratory, 1965.
<br />
<br />
4. Draper, C.S., et al., Space Navigation Guidance and Control, AGAR Dograph 105, Technivision Limited, Mardenhead, England, 1966.
<br />
<br />
5. Hoag, D.G., Apollo Navigation, Guidance and Control Systems: A Progress Report, Report E-2411, MIT Instrumentation Laboratory, April 1969.
<br />
<br />
6. Nevins, J.L., Man-Machine Design €or the Apollo Navigation, Guidance, and Control Revisited, Report E-2476, MIT Instrumentation Laboratory, January 1970.
<br />
<br />
7. Sears, N.E., Lunar Mission Navigation Performance of the Apollo Spacecraft Guidance and Navigation, Report E-2538, MIT Charles Stark Draper Laboratory, September 1970.
<br />
<br />
8. MIT's Role in Project Apollo, Report R-700, Charles Stark Draper Laboratory: Vol. I, October 1971; Vol. II, March 1972; Vol III, August 1972; Vol IV, April 1972; Vol VI July 1971.
<br />
<br />
9. The Apollo Spacecraft: A Chronology, NASA Scientific and Technical Information Office, U.S. Government Printing Office, 1973.
<br />
<br />
10. Hoag, D.G., P-357 - THE HISTORY OF APOLLO ON-BOARD GUIDANCE, NAVIGATION, AND CONTROL, September 1976
<br />
<br />
11. Apollo contributions remembered - Alice C. Waugh, News Office - MIT News, November 29, 1995<br />
<br />
<br />
<div style="text-align: center;">
* * *
</div>
<br /></div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-82686376238242740272018-01-01T08:52:00.001+00:002018-01-09T11:06:25.431+00:00DSKY Hardware (Part 15, Apollo Control Systems)<i><span style="color: #274e13;">[Since it looks like that DSKY is very popular with its companion LGC (or AGC) I add this article to fully cover the DSKY hardware (as it was 1966) in its detail. DSKY was a small and simple terminal device to today's standards. It was used by astronauts to communicate with the primary guidance computer programs. DSKY is interesting since it only had some latching relays to drive the segment displays and some simple transistor type logic to generate keycodes from the keyboard.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Today (2017) this device would be manufactured using maybe a single micro-controller and would be very simple. I am sure that even nowadays many astronauts would like to have a similar device to communicate with the guidance computer at least as a reserve device in case of some problem with the modern touch screens and high resolution displays. Its small size, simplicity and integration with the Apollo software and hardware will keep this device popular in the future also. Most of this material is from /1/. This text and drawings /1/ did have some differences with other documents but is anyway useful in its detail.</span></i><br />
<i><span style="color: #274e13;"><br />The AGC (and DSKY) was designed at the <a href="https://en.wikipedia.org/wiki/MIT_Instrumentation_Laboratory" target="_blank">MIT Instrumentation Laboratory</a> under <a href="https://en.wikipedia.org/wiki/Charles_Stark_Draper" target="_blank">Charles Stark Draper</a>, with hardware design led by <a href="https://en.wikipedia.org/wiki/Eldon_C._Hall" target="_blank">Eldon C. Hall</a>. Early <a href="https://en.wikipedia.org/wiki/Computer_architecture" target="_blank">architectural work</a> came from <a href="https://en.wikipedia.org/wiki/J._Halcombe_Laning" target="_blank">J.H. Laning Jr.</a>, <a href="https://en.wikipedia.org/wiki/Albert_Hopkins_(computer_scientist)" target="_blank">Albert Hopkins</a>, <a href="https://en.wikipedia.org/wiki/Richard_Battin" target="_blank">Richard Battin</a>, <a href="https://en.wikipedia.org/w/index.php?title=Ramon_Alonso&action=edit&redlink=1" target="_blank">Ramon Alonso</a>, and <a href="https://en.wikipedia.org/w/index.php?title=Hugh_Blair-Smith&action=edit&redlink=1" target="_blank">Hugh Blair-Smith</a>. The flight hardware was fabricated by <a href="https://en.wikipedia.org/wiki/Raytheon" target="_blank">Raytheon</a>, whose <a href="https://en.wikipedia.org/w/index.php?title=Herb_Thaler&action=edit&redlink=1" target="_blank">Herb Thaler</a> was also on the architectural team.</span></i><br />
<div>
<span style="color: #274e13;"><i><br /></i></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbw-AVZ7-qjt5ig7mVqLGJmwNviYmitNLVf2CE8aMkMA9nQ2iHOl-R_nnd3DKHA5O8MKRgboht67Rezg9CCAS1UWR6NvDmunN8aM07HnSlhI9JAHv_8sispdl-nMVT0oCCd91KSXJh3xYw/s1600/EldonHall%2540300x300.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="300" data-original-width="300" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgbw-AVZ7-qjt5ig7mVqLGJmwNviYmitNLVf2CE8aMkMA9nQ2iHOl-R_nnd3DKHA5O8MKRgboht67Rezg9CCAS1UWR6NvDmunN8aM07HnSlhI9JAHv_8sispdl-nMVT0oCCd91KSXJh3xYw/s400/EldonHall%2540300x300.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Eldon C. Hall</i></span></td></tr>
</tbody></table>
<div>
<br /></div>
<div>
<span style="color: #274e13;"><i>Most of these people can be seen in the following film</i></span><br />
<div>
<span style="color: #274e13;"><i><br /></i></span></div>
<div>
<span style="color: #274e13;"><i>YouTube video: "<a href="https://youtu.be/4u7NPRH2jMo" target="_blank">Computer for Apollo, MIT Science Reporter Film</a>"</i></span><i><span style="color: #274e13;">]</span></i><br />
<div>
<br />
<a name='more'></a><br />
<i><span style="color: #4c1130;">High resolution images to this article are available <a href="https://photos.app.goo.gl/l4CNp2qPCoB1hF2o1" target="_blank">here.</a></span></i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguhQbrH6H2d8-PBI1SzSvH4znFpy8ifqOKRfyEYfHKxmeN53T7AKZ8SEAECcP1LRV4Z60EiMqMsr4ZF80bDhJJMj8h1FqGsELvki0zn0scz8_BGTpCGtStUeZkUU9n0ysmvHcYpWufkbGA/s1600/LEM_PGNCS_Components.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="662" data-original-width="831" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEguhQbrH6H2d8-PBI1SzSvH4znFpy8ifqOKRfyEYfHKxmeN53T7AKZ8SEAECcP1LRV4Z60EiMqMsr4ZF80bDhJJMj8h1FqGsELvki0zn0scz8_BGTpCGtStUeZkUU9n0ysmvHcYpWufkbGA/s400/LEM_PGNCS_Components.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 1. DSKY was located in front of astronauts in LM and it was connected to the LGC which was located behind them.</i></span></td></tr>
</tbody></table>
<br />
<br />
<h4>
LM COMPUTER DISPLAY AND KEYBOARD, DSKY /1/</h4>
<br />
"The LM DSKY is located below the center panels of the
cockpit display and control panels.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvZvPQ6P36tRlIlo-MwxEM6EXvk7cZRcePNAHF32Zk8aYjfYBC_kTo1lW9xZff4zqksUuDyQ7rsabu_ujN5FgRd6XD6DchVg5qzCq4K8WUaFVAaMJ5TZQ622g6z6Uwd1U3mqmkcaUOtlji/s1600/DSKY_Block_Diagram_1966.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="889" data-original-width="1097" height="323" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvZvPQ6P36tRlIlo-MwxEM6EXvk7cZRcePNAHF32Zk8aYjfYBC_kTo1lW9xZff4zqksUuDyQ7rsabu_ujN5FgRd6XD6DchVg5qzCq4K8WUaFVAaMJ5TZQ622g6z6Uwd1U3mqmkcaUOtlji/s400/DSKY_Block_Diagram_1966.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 30. General DSKY Block Diagram.</i></span></td></tr>
</tbody></table>
<br />
The DSKY (figure 30) consists of a keyboard: a relay
matrix with associated decoding circuits, displays, mode and
caution circuits; and a power supply. The keyboard, which
contains several numerical, sign, and other control keys,
allows the astronaut to communicate with the LGC. The inputs
from the keyboard are entered into an input channel and
processed by the LGC.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtgk1PcqK4lhN64-w1SPgUZ4xnbmLJkNsOXLvAeFp02bqDznE8DJ4wqIpkfYRRESPTOeTxBdFSY7H6FQLa-Bim3NflNj957vEeDdcj6d7sMxrhb0H_R0zVpwrBTedllYMYD4TYDrSLLAgR/s1600/DSKY_Electronics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="837" data-original-width="638" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtgk1PcqK4lhN64-w1SPgUZ4xnbmLJkNsOXLvAeFp02bqDznE8DJ4wqIpkfYRRESPTOeTxBdFSY7H6FQLa-Bim3NflNj957vEeDdcj6d7sMxrhb0H_R0zVpwrBTedllYMYD4TYDrSLLAgR/s400/DSKY_Electronics.png" width="303" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 2. Operation of the display. Latching relays serve as high voltage drivers and memory at the same time.</i></span></td></tr>
</tbody></table>
<i><span style="color: #4c1130;"><br /></span></i>
<i><span style="color: #4c1130;">[DSKY keyboard and display operate separately. The operation of the display is shown in the above figure. By writing to the output channel 0010 (octal) AGC can write to a single pair of digits at one time. To update the whole display all pairs must be visited. Relay matrix column data sets the information which segments should be illuminated of the selected digit pair. The row select is generated from the upper part of the written word by the decoder.</span></i><br />
<i><span style="color: #4c1130;"><br /></span></i>
<i><span style="color: #4c1130;">Once a row is selected by the decoder the associated row line voltage is pulled down via diodes so that any relays connected to that line will be energized by any data written to the columns Since the relays are latching there are two coils in each relay. One coil will set it to "0" (off) and one to "1" (on). Both voltages are generated from the single bit information. Once settled the relay does not need any additional energy and will keep its state. Only one pair of digits are connected to a single row select line. So to address about 24 digits in the DSKY display about 12 lines are required. Due to the mechanical matter of the relays (long settle time) the update rate cannot be very fast and so the update operation can be visually seen and heard on the DSKY display. A feature that makes DSKY so unique among displays.]</span></i><br />
<i><span style="color: #4c1130;"><br /></span></i>
<i><span style="color: #4c1130;"><span style="color: #4c1130;">YouTube video about DSKY update rate: </span>"<a href="https://youtu.be/PF-9SyWM1Mw" target="_blank">Apollo command module computer</a>"</span></i><br />
<br />
The inputs entered from the keyboard, as well as other
information, appear on the displays after processing by
program. The display of information is accomplished through
the relay matrix. A unique code for the characters to be
displayed is formed by fifteen bits from output channel 10 (octal) in the LGC. Bits 12 through 15 are decoded by the decoding
circuits, and, along with bits 1 through 11, energize
specific relays in the matrix which causes the appropriate
characters to illuminate. The information displayed is the
result of a keycode punched in by the astronaut, or is
computer-controlled information. The display characters are
formed by electroluminescent segments which are energized by
a voltage from the power supply routed through relay
contacts. Specific inputs from the PGNCS are also applied,
through the LGC to certain relays in the matrix through
output channel 10 of the LGC. The resulting relay-controlled
outputs are caution signals to the PGNCS.
The mode and caution circuits accept direct input signals
from channels 1l, 12, and 13, without being decoded. The
resulting outputs can give an indication to the astronaut on
the DSKY and route the output signal to the PGNCS and
spacecraft."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiji5ExUVFPASnt23q0eMMcjzwPwBHOYfPN4kt1Dg6nw74yxDAThocGHM1G28mSxP2g8eCOf6yualHgZvvOoiChe9rewlDPss_99iMa-o39dkBAA7NcqnE7rIWubYfTGXfwMuu7z2lx8O5N/s1600/agc_dsky2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="768" data-original-width="1444" height="212" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiji5ExUVFPASnt23q0eMMcjzwPwBHOYfPN4kt1Dg6nw74yxDAThocGHM1G28mSxP2g8eCOf6yualHgZvvOoiChe9rewlDPss_99iMa-o39dkBAA7NcqnE7rIWubYfTGXfwMuu7z2lx8O5N/s400/agc_dsky2.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 3. Apollo Guidance Computer (AGC or LGC) and its display keyboard device DSKY.</i></span></td></tr>
</tbody></table>
<br />
<h4>
DISPLAY AND KEYBOARD (DSKY) /1/</h4>
"The DSKY provides a means of communicating with the
computer. It allows the operator to load information into
the computer, request information, initiate various programs
stored in memory, and perform tests on the computer and
other subsystems of the PGNCS system. The DSKY also provides
an indication of status and caution changes which may occur
within the computer.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp1OQBOa2O6X4SpJcc6GQyHytE7ERe1mf55i_4UFJxZjMLAXMUOmHkZixvYfHEPcTiIkyJPaW_8WorEBLBu0J5o337MtQ5nwtw-CA6Sjtqr7Vg-UCcU79gDMtSeDSLb1tGhRuu7BLlCqNp/s1600/p+pl12.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="466" data-original-width="550" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp1OQBOa2O6X4SpJcc6GQyHytE7ERe1mf55i_4UFJxZjMLAXMUOmHkZixvYfHEPcTiIkyJPaW_8WorEBLBu0J5o337MtQ5nwtw-CA6Sjtqr7Vg-UCcU79gDMtSeDSLb1tGhRuu7BLlCqNp/s400/p+pl12.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 4. A miniature latching relay.</i></span></td></tr>
</tbody></table>
<br />
The LGC has one DSKY located on the front wall of the LEM
cabin. The CMC has two associated DSKY's - one is mounted on
the main display and control panel (main DSKY) in the lower
equipment bay of the command module, the second is mounted
on the navigation display and control panel (navigation
DSKY). All three DSKY’s are electrically identical. As such,
the two in the command module are interchangeable.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBSAwz41NAz3wuYFv9Pr8fSJGoKIu_tgcWLO8x5Hex7kh1JfmIGv6VUdvDIcNvr5E-lyZEUy7d6onCiz_R4lad8UmwVH4VKFQrG_z0NRqFHig1oVfLWHjtsH1Y6HpQbqCWe8O9CLmtMWjY/s1600/PL-12+Dimensions.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="756" data-original-width="1300" height="232" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBSAwz41NAz3wuYFv9Pr8fSJGoKIu_tgcWLO8x5Hex7kh1JfmIGv6VUdvDIcNvr5E-lyZEUy7d6onCiz_R4lad8UmwVH4VKFQrG_z0NRqFHig1oVfLWHjtsH1Y6HpQbqCWe8O9CLmtMWjY/s400/PL-12+Dimensions.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 5. Relay dimensions.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">1 DSKY Functional Description.
</span></b><br />
<br />
The DSKY (figure 222) consists of a keyboard, power supply,
decoder, relay matrix, status and caution circuits, and
displays<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-wuz1C_zzOI16RcO62QxaNqFZs_-kOaMJcjQw_QkibvbIFoMQIa61DKAos7kxwh25iPZ-rEX0stktCb9_V08zLmHa_uV73vJQHeOE6cA1zLY6jYSIDXmcafU9Ux4UimNEIm_l-qv5Dh1E/s1600/222.+DSKY_Functional_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="925" data-original-width="1600" height="231" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-wuz1C_zzOI16RcO62QxaNqFZs_-kOaMJcjQw_QkibvbIFoMQIa61DKAos7kxwh25iPZ-rEX0stktCb9_V08zLmHa_uV73vJQHeOE6cA1zLY6jYSIDXmcafU9Ux4UimNEIm_l-qv5Dh1E/s400/222.+DSKY_Functional_Diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 222. DSKY Functional Diagram</i></span></td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipPcxo4D-6lafPVC3QP3r7j0oeeOyxj4SKqM5ugV?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The keyboard contains the key controls with which
the astronaut operates the DSKY. Each of the key controls is
illuminated by 115 VAC at 400 CPS. Inputs to the computer
initiated from the keyboard are processed by the program.
The results are supplied to either the decoder and relay
matrix or the status and caution circuits for display. Each
key when pressed, with the exception of STBY, will produce a
5 bit code. The keycode is entered into the computer and
initiates an interrupt to allow the data to be accepted. The
key reset signal (+28 volts) is generated each time a key is
released, the signal conditions the computer to accept
another keycode. The reset code and reset signal (+28 volts)
is used when the operator wishes to extinguish certain
display indicators. It also allows a check to determine
whether a particular indication is transient or permanent.
The clear code is used when the operator wishes to clear
displayed sign and digit information. Key release turns the
control of displaying information on the DSKY over to the
computer. The standby signal (+28 volts) initiates placing
the computer into the standby mode and into the operate mode
when pressed a second time.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7IeB-7HEQwMI8UTruFfW88jy4BwTLQKpyWtZ9Ksvdz9H0jV3baURC3SR-X4V3YChGdeRdemrqt0CoEdexLUV7OpK4ok7pGae1_wAJMbC2Fft6Ba4JoPinRPmWlW5iIxpk82PzbK8BFalf/s1600/3-7_DSKY.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1128" data-original-width="997" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh7IeB-7HEQwMI8UTruFfW88jy4BwTLQKpyWtZ9Ksvdz9H0jV3baURC3SR-X4V3YChGdeRdemrqt0CoEdexLUV7OpK4ok7pGae1_wAJMbC2Fft6Ba4JoPinRPmWlW5iIxpk82PzbK8BFalf/s400/3-7_DSKY.png" width="352" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Figure 6. DSKY external parts.</i></td></tr>
</tbody></table>
<br />
The power supply utilizes +28 volts and +14 volts from the
computer power supply and an 800-CPS sync signal from the
timer to generate a 250 VAC, 800 CPS display voltage. The
display voltage is applied to the displays through the relay
matrix and status and caution circuits.
<br />
<br />
The decoder receives a four bit relay word (bits 12 through
15) from channel 10 in the computer. The decoded relay word,
in conjunction with relay bits 1 through 11 from channel 10,
energizes specific relays in the matrix. The relays are
energized by the coincidence of two signals: a selection
signal from the diode matrix in the decoder which produces a
row selection signal and relay bits which produce column
selection signals. Relay selection allows the display
voltage (250 VAC) from the DSKY power supply to be routed to
the proper sign and digit indicators. Relay selection also
allows the alarm common (0 VDC) or +5 volts from the PGNCS
system or the spacecraft to be routed through the relay to
one of the following: PGNCS system (caution signals), the
spacecraft (caution signals), or proper status and caution
indicators. The PGNCS caution signals from the relay matrix,
represented by 0 VDC, are PGNS CAUTION, TRACKER, and GIMBAL
LOCK. The status and caution indicators, illuminated by the
+5 volts are: PROG, TRACKER, GIMBAL LOCK, and NO ATT. All
relays associated with the relay matrix are latching t3cpe
relays.
<br />
<br />
The status and caution circuits receive all status and
caution signals from the computer. Each signal is applied to
a driver circuit and associated relay. When a relay is
energized, it allows the voltage from the DSKY power supply
(250 VAC), or +5 volts or 0 VDC from the PGNCS or spacecraft
to be routed to the proper display indicators or equipment.
The voltage from the power supply is routed through a relay
to the computer activity indicator (COMP ACTY). The +5 volts
is routed through relays to the following status and caution
indicators: UPLINK ACTY, RESTART, OPR ERR, KEY REL, and
TEMP.
<br />
<br />
The LGC status and caution signals, represented by 0 VDC or
an open circuit, are ISS WARNING, STBY, LRDR POS CMD, RR
AUTO TRACK ENABLE, LGC WARNING, and PGNS CAUTION.
<br />
<br />
In the CMC, the status and caution signals, represented by 0
VDC or an open circuit, are ISS WARNING, STBY, SIVB INJ, SEQ
START, SIVB CUT-OFF, CMC WARNING, and PGNS - G/N CAUTION.
<br />
<br />
All relays associated with the status and caution circuits
are non-latching.
<br />
<br />
The displays consist of sign and digital (operational and
data display) and status and caution indicators. The sign
and digital indicators allow the astronaut to observe the
data entered or requested from the keyboard. The status and
caution indicators present an indication of any variance
from certain normal operations.
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsmsiZT6TuwYSfpCBMjgCT8mWO3-fHBXLNvFpgtb4x7FeTW4EzlpHS3PXFPwTpntXc78CQ_QzM8mVYvkQYC72bYpzjseaGpAz3NpvXakCEMtLLi2VpmHfpV3pRyDGCD3e9z7gCs4ajiZ3Y/s1600/A19720317000cp01.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="600" data-original-width="597" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsmsiZT6TuwYSfpCBMjgCT8mWO3-fHBXLNvFpgtb4x7FeTW4EzlpHS3PXFPwTpntXc78CQ_QzM8mVYvkQYC72bYpzjseaGpAz3NpvXakCEMtLLi2VpmHfpV3pRyDGCD3e9z7gCs4ajiZ3Y/s400/A19720317000cp01.jpg" width="397" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 7. DSKY front face. The larger DSKY (24.1 x 25.4 x 15.2cm or 9 1/2 x 10 x 6 in.) in Smithsonian Collection. Possible just used in tests by NASA.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">2 DSKY Detailed Description.</span></b><br />
<br />
The DSKY consists of a keyboard and display section,
decoder, relay matrix, status and caution circuits, and
power supply.
<br />
<br />
<br />
<i><b>2.1 Keyboard and Display.
</b></i><br />
<br />
The keyboard section (figure 223) contains 10 digit keys (0
through 9) and 9 operational keys (VERB, NOUN, CLR, PRO, KEY
REL, ENTR, RESET, +, and -).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQI2B7QzWLTE8FFnRmxFl1AIOpi2iFFKp50291V4vqFxXhrqzNCuOUhyeMnR0zY4-pDAhyV0zRjoMonOc-erZ3NQGY3PpNCqMad7njohbguf2_tGXzBdT0YtaeCWEfs9NFOORVEEAxXjNk/s1600/223.+DSKY_Front_Panel.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="671" data-original-width="681" height="392" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjQI2B7QzWLTE8FFnRmxFl1AIOpi2iFFKp50291V4vqFxXhrqzNCuOUhyeMnR0zY4-pDAhyV0zRjoMonOc-erZ3NQGY3PpNCqMad7njohbguf2_tGXzBdT0YtaeCWEfs9NFOORVEEAxXjNk/s400/223.+DSKY_Front_Panel.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 223. Keyboard and display front panel.</i></span></td></tr>
</tbody></table>
<br />
Except for operational key PRO,
all of the keys, when pressed, generate different five-bit
binary keycode which is applied to an input channel of the
input-output section. In the LGC, the keycode is applied to
channel 15 of the input/output section. In the CMC, the
keycode from the main DSKY is applied to channel 15: the
keycode from the navigation DSKY is applied to channel 16.
The keycodes are shown beside their respective keys on
figure 223. The PRO key, when pressed, generates +28 volts
through key contacts to the standby circuits in the
computer. This key is also used to allow the program to
proceed without data in lieu of entering VERB 33. Each of
the 18 keys is illuminated by 115 VAC, 400 CPS from the
spacecraft.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4VcWnwOn1tVW4erlx_vKpPnPPbMhMILWndBiXuUiz8a-dn_OzbQy2lDkxKjk_87N36dTayrlZ973gBliYWWi2qq6PqKS54pfkhE2-zNuiFEbPlF04OK1wpWRdLLcYT7crksi3Dxzw5zI4/s1600/1280px-Apollo_DSKY_interface.svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="905" data-original-width="1280" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4VcWnwOn1tVW4erlx_vKpPnPPbMhMILWndBiXuUiz8a-dn_OzbQy2lDkxKjk_87N36dTayrlZ973gBliYWWi2qq6PqKS54pfkhE2-zNuiFEbPlF04OK1wpWRdLLcYT7crksi3Dxzw5zI4/s400/1280px-Apollo_DSKY_interface.svg.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 8. Meaning of various parts in DSKY.</i></span></td></tr>
</tbody></table>
<br />
The key contacts (figure 224) are connected in series to
ensure that only one keycode will be produced at one time.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiWrDLYI6EVNzRWJu9QdhWoqEZRx2QUkqmjT81adYICpJ0Gzc1KK9q1tbpbofPlvpFJ50Y5q8nUrtgzYfjGqgTfQjiWO2C5EIJomRPNlny63bf8HXB74zaU73zbRa3E_1ESENpI6NTl24J/s1600/224.+DSKY_Keyboard_Schematics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="989" data-original-width="825" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiiWrDLYI6EVNzRWJu9QdhWoqEZRx2QUkqmjT81adYICpJ0Gzc1KK9q1tbpbofPlvpFJ50Y5q8nUrtgzYfjGqgTfQjiWO2C5EIJomRPNlny63bf8HXB74zaU73zbRa3E_1ESENpI6NTl24J/s400/224.+DSKY_Keyboard_Schematics.png" width="332" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 224. DSKY Keyboard Schematic Diagram.</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipPi9F9MXN14yoMQw4v1yjgZ3QZBOCrQqjqd3hcU?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The binary keycode is produced by applying +28 volts through
the key contacts to a diode network. The keycode initiates a
program interruption (KEYRUPT) in the computer. When a key
is released, signal KEYRST resets the input channel, thus
clearing it for the acceptance of another keycode. A key
must be released before another key is pressed to have
information processed by the computer.
<br />
<br />
<i><span style="color: #4c1130;">[Since DSKY keyboard is using toggle switch buttons with NO (Normally Open) and NC (Normally Closed) contacts it can tell to the computer that any button is pressed or all buttons are not pressed. That is done so that normally all buttons are connected via their NC contacts in series to the KEYRST line (which is high all the time when nothing is pressed). But when something is pressed the line KEYRST drops down and again when it is released the KEYRST line return to high state. The series connection also prevents any double key mixed signals to be sent to the computer.]</span></i><br />
<i><span style="color: #4c1130;"><br /></span></i>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnHS5Q4cvVBnMI0F73m8zbAS3w7FzRqG4Dzz7JKV6PII_nqFMg2I8IfvD1We0VSQJiBhYojXn37MqIZSEkMeX1rGjc6ol1RxpiL0v4q7OLDbJYpWhTnPrKPsAEKEgb8JtqyDxX9GMIZRzA/s1600/DSKY_D_Circuit.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="582" data-original-width="799" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnHS5Q4cvVBnMI0F73m8zbAS3w7FzRqG4Dzz7JKV6PII_nqFMg2I8IfvD1We0VSQJiBhYojXn37MqIZSEkMeX1rGjc6ol1RxpiL0v4q7OLDbJYpWhTnPrKPsAEKEgb8JtqyDxX9GMIZRzA/s400/DSKY_D_Circuit.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Figure 9. "D" circuits after the keyboard in the computer inputs take care of removing false key presses (bounces) and other disturbances.</i></td></tr>
</tbody></table>
<i><span style="color: #4c1130;"><br /></span></i>
<i><span style="color: #4c1130;">[The diode matrix schematic (figure 224.) above is a bit alone hanging and we would like to know how are the keycode lines actually connected to the computer. That can be seen in the previous DSKY article <a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4olH9LDXi45UEDXor2xj6n_oPOPUMnLF4IToj-2PVrVASLy9x5E3z6_CY0npZoorwfpNQOPzJhJ7v5jDNI-ww4c6Im_VXT5Y87YkMkfvZWeZxJdb2Tpq_9H3swTqKJ8u5mnk4fNhbIuqN/s1600/14_lgc_dsky5.png" target="_blank">here</a> and repeated in the above figure. All keycode diode lines and buttons are connected using "D" circuits which are low pass filters and trigger circuits. Lower energy spikes will not have enough energy to charge the low pass filter capacitor in the input circuit to so high value that the input port would trigger to high state. But when a key is pressed and it connects the 20 k charging resistor to the 28 V line and it is kept there at least about 10 milliseconds there will be enough potential to set the signal input line to value "one". In that way the low pass filter removes key contact bounces and spikes in the long lines to the computer. Additionally the required KEYRST signal to follow any valid keycode will remove additional key bounces, disturbances and false key presses. </span></i><i><span style="color: #4c1130;">Building a keyboard this way makes it very reliable.]</span></i><br />
<br />
The display section (figure 223) contains 24 digit displays
(21 for numerical and 3 for sign) and 15 indicators (spare
included). The 24 digit displays (DSl except COMP ACTY) and
15 indicators (DS2 plus COMP ACTY) are arranged as shown in
figure 223. The displays and indicators are
luminescent-coated-glass assemblies which glow when a
voltage is applied to the coating. The displays (digit and
sign) are segmented, and a display voltage of 250 VAC from
the DSKY power supply is applied to each segment through
contacts in the relay matrix. The indicators are made in one
piece. Except for COMP ACTY which receives 250 VAC, all the
indicators receive a display voltage of +5 volts from the
spacecraft through relay contacts. The brightness of certain
displays (digit, sign, and COMP ACTY) varies as a function
of the voltage and frequency applied to the coating. The
voltage can be varied using the brightness control on the
astronauts control panel in the PGNCS.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrBFBwrOSAzjGLR1Wc6zn8cZq5KGSSI4tHRHXAAQAjHcQV8f96fpO7L2uX-slTkeWEY4wg8L2jTE7XxkJcjCreYsh4YKSIulSFjU3Ah8QUqJ0l-o-uss7lMvGEMJOzlW7hTdzIoS76-eMC/s1600/lf+%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1504" data-original-width="1600" height="375" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrBFBwrOSAzjGLR1Wc6zn8cZq5KGSSI4tHRHXAAQAjHcQV8f96fpO7L2uX-slTkeWEY4wg8L2jTE7XxkJcjCreYsh4YKSIulSFjU3Ah8QUqJ0l-o-uss7lMvGEMJOzlW7hTdzIoS76-eMC/s400/lf+%25281%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 10. DSKY back face.</i></span></td></tr>
</tbody></table>
<br />
The standard procedure for communicating with the computer
is to press seven keys in the following sequence:
VERB-DIGIT-DIGIT, NOUN-DIGIT-DIGIT, and ENTR.
<br />
<br />
Pressing the VERB key on the keyboard clears the VERB
displays on the display and indicators. The two digits
punched in next are interpreted as a VERB code and displayed
in the VERB section. This same operation occurs using the
NOUN and two digits. The operation of the VERB-NOUN code is
not initiated in the computer until key ENTR is pressed. If
an error is noticed in either the VERB or NOUN before ENTR
is pressed, it may be corrected by repunching either the
VERB or NOUN key and the correct code.
<br />
<br />
If the VERB-NOUN combination punched in requires additional
data to be furnished by the operator, the VERB and NOUN
displays flash once every 1.5 seconds after the ENTR key has
been pressed. The flashing indicates that the operator
should punch-in the required data on the keyboard. After
punching in the required data and the ENTR key, the flashing
ceases.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgu-p6RTN2JKAfOlaYwErSU6YAgjw5yR_OvrIZ3glrShYpiQqwIXrD-tauBmD3JNAvLwPQ3_ueFuvrZjW4Uj3YFZacdFEoHsjFwbeNdVyINQV5zOxVLKs2GhdmV8-tyAXcoLt5_WkNGSXZG/s1600/6375049589_8628fc1c41_o.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1300" data-original-width="1600" height="325" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgu-p6RTN2JKAfOlaYwErSU6YAgjw5yR_OvrIZ3glrShYpiQqwIXrD-tauBmD3JNAvLwPQ3_ueFuvrZjW4Uj3YFZacdFEoHsjFwbeNdVyINQV5zOxVLKs2GhdmV8-tyAXcoLt5_WkNGSXZG/s400/6375049589_8628fc1c41_o.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 11. Inside DSKY.</i></span></td></tr>
</tbody></table>
<br />
Octal and decimal data words can be punched in. The computer
assumes that an octal data word will be entered if a sign
key (+ or -) is not pressed. If digit key 8 or 9 is pressed
while loading an octal data word, indicator OPR ERR flashes
once every 1.5 seconds. Whenever key (+) or key (-) is
pressed, the corresponding signal is displayed and the
computer assumes that a decimal word is to be entered. If an
error is noticed while punching in either octal or decimal
data, the CLR key can be pressed and the correct entry can
be made if the ENTR key has not been pressed. All data words
entered must be either octal or decimal; combinations of
octal and decimal are not permitted.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWxGTcdofIfBBR4500KaQIBCrWYQaY9xCwQBeWpHO9kz_-KiFHSiheWPnCPwnKdzmti2scypL4vEK5UE0vDTanbVbvVIIP82yRM1CN4arydS822u17xMCF8JuDDcwMZpoeYoyZvZOHVUSW/s1600/6375049609_fdd1aee02d.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="207" data-original-width="500" height="163" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWxGTcdofIfBBR4500KaQIBCrWYQaY9xCwQBeWpHO9kz_-KiFHSiheWPnCPwnKdzmti2scypL4vEK5UE0vDTanbVbvVIIP82yRM1CN4arydS822u17xMCF8JuDDcwMZpoeYoyZvZOHVUSW/s400/6375049609_fdd1aee02d.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 12. Inside DSKY.</i></span></td></tr>
</tbody></table>
<br />
To eliminate the flashing of indicator OPR ERR due to
irregular keyboard entrys, key RSET must be pressed. In
addition to the keycode, a hard wired signal (+28 VDC) is
applied to the computer. Both the keycode and hard wire
signal extinguish the status indicator OPR ERR as well as
the five caution indicators: TEMP, GIMBAL LOCK, PROG,
RESTART, and TRACKER. Thus, key RSET may also be used to
test for the presence of a continuous caution rather than a
transient caution condition.
<br />
<br />
<br />
<b><i>2.2 Decoder.
</i></b><br />
<br />
The decoder (figure 225) contains four relay word drivers
(circuits 002 and 003 make up one driver), a diode matrix,
and 12 row select drivers.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyi6u1b2WgjbYJL9BySsrqj1YBQBc1ZAIQiLRnqiuzml2LvVqR9pVD2SmWd6pqL0FN5i31Io36YxDpYcvvESZ0P5J9NiAG_wmlWONigS1lJ2ms3nkzYvpfvSA8Fav1xoZrqyq2MsbQwA10/s1600/225.+DSKY_Decoder_Schematics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="978" data-original-width="1354" height="288" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyi6u1b2WgjbYJL9BySsrqj1YBQBc1ZAIQiLRnqiuzml2LvVqR9pVD2SmWd6pqL0FN5i31Io36YxDpYcvvESZ0P5J9NiAG_wmlWONigS1lJ2ms3nkzYvpfvSA8Fav1xoZrqyq2MsbQwA10/s400/225.+DSKY_Decoder_Schematics.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 225. DSKY Decoder Schematic Diagram.</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipOEqRzj2PgfqqxASjRRO2tl702SLCLN_xbjkX9H?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The relay word drivers receive
bits 15 through 12 of channel 10. Combinations of these 4
bits select 1 of 12 rows of relays in the relay matrix. The
12 code combinations from channel 10, are shown beside their
particular row selection number on figure 225. For
simplification only the selection of row 1 is discussed. The
code for row 1 selection (0001) is inverted in the interface
circuits (A25) and applied to DSKY connector J9 as signals
CE228 through CE225. To identify row 1, signals CE228
through CE226 are logic one's and signal CE225 is a logic
ZERO. A logic ONE shuts transistor Q1 off, which holds
transistor Q2 off and allows transistor Q3 to conduct.
Therefore, the X outputs of circuits controlled by signals
CE228 through CE226 are logic ONE'S, and the Y output of the
circuit controlled by signal CE225 is a logic ONE.
<br />
<br />
The diode matrix receives the 8-bit output from the four
relay word drivers. The matrix is wired so each 8-bit input
produces a logic ONE on only one output line to the word
drivers. For row 1 selection, diode CR53 of modules D2, D3,
and D4, and diode CR63 of module D5 must be reverse biased.
When these diodes are not conducting, row select driver
circuit 004 on module D1 is activated. A current path is
provided from +28 volts of the row selection driver voltage
source (through transistor Ql, R8 of CKT 004, CR44, R9) to 0
VDC. Thus, parallel transistors Q4 and Q5 conduct and supply
0 VDC, representing row 1 selection, to the relay matrix.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikXAJbqj3pmo8MUsg30KBvKF3kU_XFvPYj-lbwNcFeLRnXuAgyKaNSCuOT7Bd86uGm36M7n90RtJB1yBfk4nblsnI8GHIM1PaF6ulR2Ao0gBi_0kOUg3OE767ftBK4VvRmn82JbjLjjnRH/s1600/6375049637_afc0369cdc.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="392" data-original-width="500" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikXAJbqj3pmo8MUsg30KBvKF3kU_XFvPYj-lbwNcFeLRnXuAgyKaNSCuOT7Bd86uGm36M7n90RtJB1yBfk4nblsnI8GHIM1PaF6ulR2Ao0gBi_0kOUg3OE767ftBK4VvRmn82JbjLjjnRH/s400/6375049637_afc0369cdc.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 13. DSKY bottom.</i></span></td></tr>
</tbody></table>
<br />
The bottom row of diodes in the diode matrix (CR54 of
modules D2 through D5} are used to detect the presence of
logic ZERO'S in bits 12 through 15 of channel 10. During
normal operation at least one of the four diodes is forward
biased and applies 0 VDC to the row selection driver voltage
source. This 0 VDC is needed to supply a row selection
signal (0 VDC) to the relay matrix as discussed previously.
If the four most significant bits of channel 10 are ZERO'S,
all four diodes are reverse biased and +28 volts (+28 BC)
are applied to the input of the row selection driver voltage
source. An input of +28 volts turns transistor Q2 on which
in turn keeps transistor Q3 off. With no output from Q3,
transistor Ql is held off and the output of transistor Ql is
effectively an open circuit. Thus, there is no voltage
source for circuit operation of any row selection driver
circuit.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo4nyEiJg5mVi3KsWmjLHlTlmsqbtB3rdSD8beeui0KMi5sF0Fo0emWD_F3Rja69B3j_Rf0-xmo6C3GzlR7lasRn-WN7yEMI58Q-1iSO3d5OC-OwrGTYUZ9TmAVNg7DCeH9_kfi9waq5Gu/s1600/226.+DSKY_Indicator_Driver_Modules_D1-D6.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="619" data-original-width="1600" height="153" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo4nyEiJg5mVi3KsWmjLHlTlmsqbtB3rdSD8beeui0KMi5sF0Fo0emWD_F3Rja69B3j_Rf0-xmo6C3GzlR7lasRn-WN7yEMI58Q-1iSO3d5OC-OwrGTYUZ9TmAVNg7DCeH9_kfi9waq5Gu/s400/226.+DSKY_Indicator_Driver_Modules_D1-D6.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 226. DSKY Indicator Driver Modules (D1-D6).</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipOW0C9lqwDll7vwoMSyYu2-3YqUiakjxkGdBcys?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The indicator driver module circuits (figure 226) are used
in making up the decoder, relay matrix, and status and
caution circuits. They are introduced at this time to assist
in better understanding the previously mentioned areas. All
six indicator driver modules (D1 through D6) are identical
and interchangeable.
<br />
<br />
<br />
<b><i>2.3 Relay Matrix.
</i></b><br />
<br />
The relay matrix (figure 227) consists of 11 relay bit
drivers and 12 rows of latching relays.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid7qQppqVMe1392ZHUMx02nVUTMtnmIa62xbeahMI8_usZ4VmlwXJY-a9UJH_OA14OzkM7VbClkJbuJvGl2EEvSK_i3O9qHEQ51XHlRBUWLpJfUGAqmrYfJBrTllJhSd48KQZus2H1-8JY/s1600/227.+DSKY_Relay_Matrix_Schematic_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="628" data-original-width="1600" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid7qQppqVMe1392ZHUMx02nVUTMtnmIa62xbeahMI8_usZ4VmlwXJY-a9UJH_OA14OzkM7VbClkJbuJvGl2EEvSK_i3O9qHEQ51XHlRBUWLpJfUGAqmrYfJBrTllJhSd48KQZus2H1-8JY/s400/227.+DSKY_Relay_Matrix_Schematic_Diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 227. DSKY Relay Matrix Schematic Diagram.</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipNyugico5VECarrqhff9dS2-nVtuWFqfvO2IWZb?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
Each relay bit driver accepts 1 of 11 bits (11 through 1) of
channel 10. For simplification only bit 11 (circuit 006 on
module D6) is discussed. When bit 11 of channel 10 is a ONE,
it is inverted in the interface circuits (A25) and applied
to DSKY connector J9 as signal CE224. A ZERO input to
circuit 006 turns transistor Q8 on which switches transistor
Q9 off. Thus, +28 volts is present on pin 10 (TURN-ON) of
the column of relays dealing with the plus and minus sign
display. With a row selection signal from the diode matrix
(0 VDC) and a column select signal from a relay bit driver
(+28 volts), a single relay within the relay matrix is
controlled.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif0ox7UxSU-2NTyOBba7imJ5J6qmRZ0T44IZGCJFBAmXu3RjkvlTYI3HZhYu2HlIumZ5jQSXtgZDRoZTN0Yz1veBnCGrftRRlxG7bHIGa1qsVQFYv5Wf1t0-L4ErrtVMnUaG3ls4JoT3f2/s1600/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966+%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="934" data-original-width="900" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif0ox7UxSU-2NTyOBba7imJ5J6qmRZ0T44IZGCJFBAmXu3RjkvlTYI3HZhYu2HlIumZ5jQSXtgZDRoZTN0Yz1veBnCGrftRRlxG7bHIGa1qsVQFYv5Wf1t0-L4ErrtVMnUaG3ls4JoT3f2/s400/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966+%25281%2529.jpg" width="385" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 14. Another picture of DSKY.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #4c1130;">[Almost all Block II DSKYs in the Smithsonian Collection have different external sizes, most usually the numbers are about (20.3 x 20.3 x </span></i><i><span style="color: #4c1130;">16.5 </span></i><i><span style="color: #4c1130;">cm </span></i><i><span style="color: #4c1130;">(8 x 8 </span></i><i><span style="color: #4c1130;"> x 6 1/2 </span></i><i><span style="color: #4c1130;">in.)) or larger. There was also a block I DSKY but it was totally different kind of. This information is from Smithsonian Institute.]</span></i><br />
<br />
<i><span style="color: #4c1130;">Link to <a href="https://airandspace.si.edu/collections/search/DSKY" target="_blank">Smithsonian Dskies</a> </span></i><br />
<br />
All of the relays in the relay matrix control the DSKY
displays. Row 12 controls the indicators associated with the
status and caution indicators (DS2) and, in addition,
supplies a PGNS CAUTION signal to the display and control
section of the PGNCS<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1jsNnEOMotLaoCj4hs6poaYRycSySlnJdYNuxzAnh0eE8xCcvmDPFqCD4a40rRlSm0jcOZQaCVP4115PpGSGRLZgfNUHVNDehXLqSFmsDXRBM9QXVMtPJ3xwvXn95b-TxsGqDRmY6XxS_/s1600/C.+DSKY_Table_Relay_Matrix_Codes.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="606" data-original-width="914" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1jsNnEOMotLaoCj4hs6poaYRycSySlnJdYNuxzAnh0eE8xCcvmDPFqCD4a40rRlSm0jcOZQaCVP4115PpGSGRLZgfNUHVNDehXLqSFmsDXRBM9QXVMtPJ3xwvXn95b-TxsGqDRmY6XxS_/s400/C.+DSKY_Table_Relay_Matrix_Codes.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Table C. Relay Matrix Codes.</i></span></td></tr>
</tbody></table>
<br />
Table C relates the content of channel
10 to the row and column selected and the digit or indicator
display controlled by the individual relay. Five relays are
required to display one digit. Relay bit drivers 10 through
6 control the display of one digit and relay bit drivers 5
through 1 control the display of a second digit. Relay bit
driver 11 causes the display of a plus or minus sign. The
five-bit code necessary to display digits 0 through 9 in any
display location is listed in table C1 below.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQXhH4daqBv_PR-MtjmSBnrxvsHyc7CPQ0ytTEmSrLYk8B7S-lpQinexPOu5UVpKPUZUruA8WiIdPz4aP5F-dFjyzf_UKCdMAQwxhV3xJJr8_KkP-boRBVmYn-Iyvm4UHo7zAqzEx1knOT/s1600/C1.+DSKY_Table_Digit_Codes.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="740" data-original-width="912" height="323" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQXhH4daqBv_PR-MtjmSBnrxvsHyc7CPQ0ytTEmSrLYk8B7S-lpQinexPOu5UVpKPUZUruA8WiIdPz4aP5F-dFjyzf_UKCdMAQwxhV3xJJr8_KkP-boRBVmYn-Iyvm4UHo7zAqzEx1knOT/s400/C1.+DSKY_Table_Digit_Codes.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Table C1. Display Segment Digit Codes.</i></span></td></tr>
</tbody></table>
<br />
The relays
representing REG3-POS1 of row 1 are used as an example. A
logic ONE indicates that the relay is energized. For
identification of display locations refer to figure 228.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8qcmek1bGykXOPPzNt_mbbOU1RghTAVU4K9pjNE9oJPXKhL75dLIvKij1ZLMX3gd4e8FnLEmOHSnMaZul9JBCvTZ1m5uQYRoyB5ARkYxZa3E9c8lufuLTNclBWlBGPWQfu29pm0xYUHNn/s1600/228.+DSKY_Display_Locations.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="683" data-original-width="708" height="385" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8qcmek1bGykXOPPzNt_mbbOU1RghTAVU4K9pjNE9oJPXKhL75dLIvKij1ZLMX3gd4e8FnLEmOHSnMaZul9JBCvTZ1m5uQYRoyB5ARkYxZa3E9c8lufuLTNclBWlBGPWQfu29pm0xYUHNn/s400/228.+DSKY_Display_Locations.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 228. DSKY Display Locations.</i></span></td></tr>
</tbody></table>
<br />
Energizing the proper relays within the relay matrix (rows 1
through 11) allows approximately 250 VAC from the DSKY power
supply to be routed through the relay contacts to the
various segments of the electroluminescent digit and sign
indicators. Figure 229 illustrates the relays, their codes,
and a display coding key.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_mMV3oyzkW6BbYqZteftFvXLIpP5dwNP-pvbdyf9QMJJyAf3bNBhF3atFCSY4WlceRxw5XRFs9bV8zIoOmVn-hJvc28fgegEDKFdxa-UuTEiByKFL9Lf55k-nBn5FOjyxAd7rypKS27ay/s1600/229.+DSKY_Relay_Matrix_Signal_Flow_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="723" data-original-width="1600" height="180" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_mMV3oyzkW6BbYqZteftFvXLIpP5dwNP-pvbdyf9QMJJyAf3bNBhF3atFCSY4WlceRxw5XRFs9bV8zIoOmVn-hJvc28fgegEDKFdxa-UuTEiByKFL9Lf55k-nBn5FOjyxAd7rypKS27ay/s400/229.+DSKY_Relay_Matrix_Signal_Flow_Diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 229. DSKY Relay Matrix Signal Flow Schematic Diagram.</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipOFsWaaLKcEfv9-m6dY2zkAOvlEwxxLvW8uzNpS?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
Energizing a relay in row 12 allows +5 volts from the
electrical power system in the spacecraft to be routed
through the relay contacts to a status or caution indicator.
Relays K16, K17, and K18 are spares. In addition, relays
PROG, TRACKER, and GIMBAL LOCK receive the signal alarm
common from the spacecraft and, when energized, supply
signal PGNS CAUTION to the PGNCS.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1peajKIDBRdQpSpe3zS2G5DiSpk9F-8XEpTTeIbhBDXskWiMNATv2hyphenhyphenV-T9mS9Jrv0W3gAlbLmLiUkaQntaMv9xa_iULYN2uPTc5d749WaAc9Kwf0f6hbXG64we6vBuTeHpOb7IPT96ZC/s1600/A19720315000cp01.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1600" data-original-width="1569" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1peajKIDBRdQpSpe3zS2G5DiSpk9F-8XEpTTeIbhBDXskWiMNATv2hyphenhyphenV-T9mS9Jrv0W3gAlbLmLiUkaQntaMv9xa_iULYN2uPTc5d749WaAc9Kwf0f6hbXG64we6vBuTeHpOb7IPT96ZC/s400/A19720315000cp01.JPG" width="391" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 15. Early "Block I" DSKY design. It was never flown. </i></span></td></tr>
</tbody></table>
<br />
<br />
<b><i>2.4 Status and Caution Circuits.
</i></b><br />
<br />
The status and caution circuits for the LGC (figure 230)
consist of driver circuits and associated non-latching
relays.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOlAklZe2gSiJN0Kik7SkiZVh3xJ1RnmyEIVemiw87BPV8HVNSzUVyeboEdZ0pTk4zNGlTS_-KEnTWPv8W7NeveON_E4wlhTIY6oWkZ2jF8GH8MCwA5zjEV70qwqRoV5eeKbE3xp5pAXaF/s1600/230.+DSKY_Status_and_Caution_Circuit_Schematic_Diagram_LGC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1087" data-original-width="1600" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiOlAklZe2gSiJN0Kik7SkiZVh3xJ1RnmyEIVemiw87BPV8HVNSzUVyeboEdZ0pTk4zNGlTS_-KEnTWPv8W7NeveON_E4wlhTIY6oWkZ2jF8GH8MCwA5zjEV70qwqRoV5eeKbE3xp5pAXaF/s400/230.+DSKY_Status_and_Caution_Circuit_Schematic_Diagram_LGC.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Figure 230. Status and Caution Circuit Schematic Diagram.</i></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipNql7aKNcFJo2rNX_W42P4-kxyGlap2NR8uzDn8?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
For simplification only circuit 008 on module D4 is
discussed. When signal ISS WARNING is a logic ZERO it will
turn on transistor Q13 and supply +28 volts to associated
relay K21. Relay K21 energizes and routes input signal ALARM
COMMON through its contacts to the display and control
section of the PGNCS as signal ISS WARNING. The driver
circuits and relays associated with signals LGC WARNING,
TEMP CAUTION, and RESTART also receive signal ALARM COMMON.
Signal TEMP CAUTION or RESTART causes the generation of
signal PGNS CAUTION which is applied to the PGNCS and also
causes +5 volt caution power to be applied to the respective
indicators on the DSKY front panel.
<br />
<br />
The driver circuits and relays associated with signals
UPLINK ACTY, OPR ERROR, KEY REL, and STBY will apply, when
activated, +5 volt status power to their respective
indicators on the DSKY front panel. Indicators OPR ERR and
KEY REL flash at a 1.5 CPS ACTY is physically a part of
digital indicator DSI. However, electrically it is part of
the status circuits. When signal COMP ACTY is present 250
VAC is routed through the relay contacts to its indicator.
Circuits dealing with signals RR ENABLE LOC ON, LGC WARNING.
LRDR POS CMD, and ISS WARNING do not have visual indications
on the front panel of the DSKY.
<br />
<br />
The verb-noun flash causes the verb-noun indicators to flash
by interrupting, at a 1.5 CPS rate, what normally is 250 VAC
being applied to the verb-noun relays in the relay matrix.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqjr_R4cbc9mAvhSm5jZv_f-pdN6iNt8vaq52AuJhrrWE8xfvdkRGl8CRvUHLu9Mkm-3UHfUVngeKkYyUKPy4xKDXdiDvfPAIy_S11_KKlS4Ik2z_G6fIWiPXyCBa0FDhEFUzx2oPZWUSj/s1600/231.+DSKY_Status_and_Caution_Circuit_Schematic_Diagram_CMC.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1002" data-original-width="1600" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqjr_R4cbc9mAvhSm5jZv_f-pdN6iNt8vaq52AuJhrrWE8xfvdkRGl8CRvUHLu9Mkm-3UHfUVngeKkYyUKPy4xKDXdiDvfPAIy_S11_KKlS4Ik2z_G6fIWiPXyCBa0FDhEFUzx2oPZWUSj/s400/231.+DSKY_Status_and_Caution_Circuit_Schematic_Diagram_CMC.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 231. Status and Caution Circuit Schematic Diagram (CMC).</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipN6OlZka7Zv1L4bp981xYqfj0TEgdKQwzn_Ph03?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The status and caution circuits for the CMC are illustrated
on figure 231. These circuits are identical in operation to
those in the LGC. Several interface differences exist,
however. These can be determined by examining the inputs and
outputs to the status and caution circuits for the CMC on
figure 231.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjp75h9EhJVa_lVqdwhzOu4ojv2bt90LbfWGmiyDEjNXc2pSLEsA8yW9tVBQL4KTusnyw8j8dJrYUbFzY8jdNRM7PaznQdeFgc-Onqi3z_KFveFTXhtp_3sQL-5nCxBhUIEIicPgJOmGYmW/s1600/DSKY_INTERCONNECT_HARNESS_H.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="700" data-original-width="1100" height="253" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjp75h9EhJVa_lVqdwhzOu4ojv2bt90LbfWGmiyDEjNXc2pSLEsA8yW9tVBQL4KTusnyw8j8dJrYUbFzY8jdNRM7PaznQdeFgc-Onqi3z_KFveFTXhtp_3sQL-5nCxBhUIEIicPgJOmGYmW/s400/DSKY_INTERCONNECT_HARNESS_H.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 16. A typical DSKY connection to the computer (CM navigation panel).</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><i>2.5 Power Supply.
</i></b><br />
<br />
The DSKY power supply (figure 232) utilizes +28 VDC and
+14VSW from the computer power supply, and 800 CPS from the
timer to generate a display voltage of approximately 250
VAC, 800 CPS.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhm1z_4AKcCK6WrT5DsagjPvV7YH1iXk-nID5g7Pu9FXXx0XxxdBya35ukv4w0EYkIjaoOq6FHg-w0mFdxSWWDg4YKSOnkS4nBmC3cBQN6SKy6vVKejfzYcEms_IuOlWnHgG2zHFvQQnKou/s1600/232.+DSKY_Power_Supply_Schematic_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="705" data-original-width="1600" height="176" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhm1z_4AKcCK6WrT5DsagjPvV7YH1iXk-nID5g7Pu9FXXx0XxxdBya35ukv4w0EYkIjaoOq6FHg-w0mFdxSWWDg4YKSOnkS4nBmC3cBQN6SKy6vVKejfzYcEms_IuOlWnHgG2zHFvQQnKou/s400/232.+DSKY_Power_Supply_Schematic_Diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 232. DSKY Power Supply Schematic Diagram.</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipO7DIIIfTnc4ItXiaHHCjJbn2mrO_u0YIAaqExq?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
The power supply contains three
transformer-coupled, push-pull amplifiers. The input to the
first stage is an 800-CPS square wave varying about a +14
VDC level. The dc level is controlled by the brightness
control on the astronauts' control panel. Transformers T1
and T2 step up the voltage applied to their primary
windings. The output from the third push-pull stage is
applied to saturable reactor L2.
<br />
<br />
Reactor L2 and its associated circuit regulate the voltage
applied to the displays. The displays act as a variable
capacitive load that varies as a function of the number of
indicators that are on. Changes in the load are reflected
back to the control winding of L2 through the full-wave
bridge rectifier, CRl through CR4. As the number of
indicators which are on increases, the voltage applied to
the control winding is increased. An increase in voltage
through the control winding drives reactor L2 further into
saturation and keeps the output relatively constant. If the
load decreases, the voltage through the control winding
decreases, and L2 is less-saturated."<br />
<br />
<br />
<h4>
LM DSKY in PGNCS (1966)</h4>
If we separate the PGNCS (Primary Guidance, Navigation and Control Subsection) from the overall LM Control due to the fact that it was designed by the MIT Instrumentation Lab we can show the following block diagram about the LM systems and how DSKY was situated there.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfP9Q7YWSKcn3qU1mMI5V2yFy7fqyI5GAGlaTtT5UNJ6rh3KH9S_CdESXxTAcfdh5V21BjVDv0ptQ_usYRho0E8NDwG3Z6tAoE4rgYXWo89wq6HUwlVzta4b42B_g1Z_cWXIMX5__MVZTM/s1600/PGNCS_1966_X.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="852" data-original-width="1234" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfP9Q7YWSKcn3qU1mMI5V2yFy7fqyI5GAGlaTtT5UNJ6rh3KH9S_CdESXxTAcfdh5V21BjVDv0ptQ_usYRho0E8NDwG3Z6tAoE4rgYXWo89wq6HUwlVzta4b42B_g1Z_cWXIMX5__MVZTM/s400/PGNCS_1966_X.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 17. PGNCS Block Diagram (1966)</i></span></td></tr>
</tbody></table>
<div style="text-align: center;">
<a href="https://photos.google.com/share/AF1QipMgiqpO3BG2RCZem_NdLWy8akZpVo928fno_xjuAHEUd7ms-TC42NuupCwfNOF7Qw/photo/AF1QipN6xWej9QrSKn1zoM8LeNppE65CRLP_U7RN9IeR?key=WmdjNVhRNEdOX2p0a0tEdjVIanVJRmY2WnBodVFn" target="_blank">(HiRes image)</a></div>
<br />
Additionally to these parts there was other systems like the explosive devices, other displays and controls, electrical power supply, environmental control, lighting, communications, main propulsion, reaction control, instrumentation, etc. and of course the abort guidance system (AGS) outside primary (MIT). In the above diagram we have the following block names.<br />
<br />
<ul>
<li>AOT - Alignment Optical Telescope</li>
<li>LR - Landing Radar</li>
<li>RR - Rendezvous Radar</li>
<li>CDU - Coupling Data Unit</li>
<li>DSKY - (AGC) Display and Keyboard</li>
<li>LGC - LM Guidance Computer (or AGC)</li>
<li>PTA - Pulse Torque Assembly</li>
<li>IMU - Inertial Measurement Unit</li>
<li>PSA - Power Servo Assembly</li>
<li>OSS - Optical Subsystem</li>
<li>ISS - Inertial Subsystem</li>
<li>RS - Radar Subsystem</li>
</ul>
<br />
All together LM had 12 subsystems (see <a href="https://dodlithr.blogspot.fi/2012/07/lunar-module-control-subsystems-part-8.html" target="_blank">here</a> for additional details).<br />
<br />
<br />
<b><span style="color: #0c343d;">RESOURCES
</span></b><br />
<br />
/1/ APOLLO LUNAR EXCURSION MODULE PRIMARY GUIDANCE,
NAVIGATION, AND CONTROL SYSTEM MANUAL VOLUME II OF II -
PREPARED FOR NATIONAL AERONAUTICS AND SPACE ADMINISTRATION,
MANNED SPACECRAFT CENTER BY DELCO ELECTRONICS, DIVISION OF
GENERAL MOTORS, MILWAUKEE, WISCONSIN 53201, NASA CONTRACT
NAS 9-497, 1 FEB 1966 - ND-1021042, REVISION AK, INITIAL
TDRR 26432, TYPE II, APPROVED BY NASA - link to
<a href="https://archive.org/details/acelectroniclmma00acel_0" target="_blank">https://archive.org/details/acelectroniclmma00acel_0</a><br />
<br />
/2/ <a href="https://photos.app.goo.gl/l4CNp2qPCoB1hF2o1" target="_blank">High resolution images to this article are available here.</a><br />
<br />
/3/ <a href="https://airandspace.si.edu/collections/search/DSKY" target="_blank">Smithsonian Collections</a><br />
<br />
<div style="text-align: center;">
* * *
</div>
</div>
</div>
</div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-66858795465265411022017-12-24T08:31:00.001+00:002017-12-26T05:38:32.752+00:00Extreme Points of a Great Circle - (Part 3, Great Circles)<br />
<h4>
The Northernmost and Southernmost Points of a Great Circle</h4>
If you travel from Amsterdam (P1 in Figure 1) to San Francisco (P2) or the other way around, then you first go towards the north for a while, and then towards the south for a while. All great circles except for the equator have a northernmost point (PN) and a southernmost point (PS). You can calculate them as follows.<br />
<div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; margin: 0px; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 1; word-spacing: 0px;">
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6wuQFZ5l6g5UCwPqi7eGUbV_NNDPVZLGiMftH5n3vToDVQtjUfJdL41kmh5mg_SbWOOkXv-8osd2dzLtEW8954g8IxpgT74jEFJa_E1hPBswiCvnk_zQ0A8jsz2ROtwW1U4-SYxMih15W/s1600/Figure_5.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6wuQFZ5l6g5UCwPqi7eGUbV_NNDPVZLGiMftH5n3vToDVQtjUfJdL41kmh5mg_SbWOOkXv-8osd2dzLtEW8954g8IxpgT74jEFJa_E1hPBswiCvnk_zQ0A8jsz2ROtwW1U4-SYxMih15W/s400/Figure_5.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: "times new roman"; text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Fig. 1: Northernmost and Southernmost Point on a Great Circle</i></span></span></td></tr>
</tbody></table>
<br />
<a name='more'></a>Repeating here what we already had in part 1 calculate the Cartesian coordinates of both points P1 and P2.</div>
<br />
<b><span style="color: #4c1130;">1.</span></b> Call the polar coordinates (longitude and latitude) of the first city l1 and b1, and those of the second city l2 and b2.<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>l1 = 4.9°; b1 = 52.37°;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>l2 = -122.42°; b2 = 37.77°</b><br />
<br />
<b><span style="color: #4c1130;">2</span></b>. Translate the polar coordinates of the first city P1 to the corresponding cartesian coordinates x1, y1, z1 (see Figure 2):<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4ceIIw3ANzepjZetFYoIFBio-rJLa0prGtUKZajsEUFBY1bHhEHfVEY6iFmTwHiqdt3eojut_ElrF-uxvgjfZzpXvMVY936RFVJiah-wQ991VEldiWZK2ay7-TNoFYjfRJbuCH5EJOThZ/s1600/Figure_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh4ceIIw3ANzepjZetFYoIFBio-rJLa0prGtUKZajsEUFBY1bHhEHfVEY6iFmTwHiqdt3eojut_ElrF-uxvgjfZzpXvMVY936RFVJiah-wQ991VEldiWZK2ay7-TNoFYjfRJbuCH5EJOThZ/s400/Figure_1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="background-color: white; color: #cc0000; font-family: 'trebuchet ms', verdana, arial, sans-serif; font-size: small; line-height: 18.915px;">Fig. 2: Illustration of Transformation from Polar to Cartesian Coordinates</i></td></tr>
</tbody></table>
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x1 = cos(l1)*cos(b1)<span class="Apple-tab-span" style="white-space: pre;"> </span>(1)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y1 = sin(l1)*cos(b1)<span class="Apple-tab-span" style="white-space: pre;"> </span>(2)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z1 = sin(b1)<span class="Apple-tab-span" style="white-space: pre;"> </span>(3)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x1=0.6083285;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y1=0.05215215;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z1=0.7919701;</b><br />
<br />
and similarly for the second city P2.<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x2 = cos(l2)*cos(b2)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y2 = sin(l2)*cos(b2)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z2 = sin(b2)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x2 = -0.423791;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y2 = -0.6672729;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z2 = 0.6124933</b><br />
<br />
Calculate the angular distance psi between the two cities, as seen from the center of the Earth (see Figure 3 below):<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>psi = acos(x1*x2 + y1*y2 + z1*z2)<span class="Apple-tab-span" style="white-space: pre;"> </span>(4)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>psi = 78.90289°</b><br />
<br />
<b><span style="color: #4c1130;">3.</span></b> Calculate the coordinates of the point P3 on the great circle that is 90° from the first city P1 in the direction of the second city P2 (see Figure 3):<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDcIK4LECXxZVVAfiHIqHUVUEUYaKp20YaxpojBpef1_ksT2vfvb_geVZy5vINh7Pmwy7BgdyWrLUr6HWLw54c50kizR554QhBj2UHJCOZ4FiS_-8o6A58jJ6Nohns3w7nI7wPeODVnAbU/s1600/Figure_3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgDcIK4LECXxZVVAfiHIqHUVUEUYaKp20YaxpojBpef1_ksT2vfvb_geVZy5vINh7Pmwy7BgdyWrLUr6HWLw54c50kizR554QhBj2UHJCOZ4FiS_-8o6A58jJ6Nohns3w7nI7wPeODVnAbU/s400/Figure_3.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Fig. 3. P3 is 90 degrees from P1 towards P2.</i></td></tr>
</tbody></table>
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x3 = (x2 - x1*cos(psi))/sin(psi)<span class="Apple-tab-span" style="white-space: pre;"> </span>(5)</b><br />
<div>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y3 = (y2 - y1*cos(psi))/sin(psi)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z3 = (z2 - z1*cos(psi))/sin(psi)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>x3 = -0.5511833;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>y3 = -0.6902162;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>z3 = 0.4688268.</b><br />
<br />
<b><span style="color: #4c1130;">4.</span></b> Calculate the angular distance of the first city P1 from the first special (northernmost or southernmost) point:<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi1 = atan(z3/z1)<span class="Apple-tab-span" style="white-space: pre;"> </span>(11)</b><br />
<br />
The angular distance of the second special point is 180° greater (or less, that is the same thing on a circle):<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi2 = phi1 + 180°<span class="Apple-tab-span" style="white-space: pre;"> </span>(12)</b><br />
<br />
For the great circle that passes through Amsterdam and San Francisco, we find<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi1 = 30.62449°;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi2 = 210.62449°.</b><br />
<br />
<b><span style="color: #4c1130;">5.</span></b> You can then use formula 6 to calculate the corresponding cartesian coordinates, and then formula 7ff to calculate the polar coordinates as in part 1.<br />
<br />
The corresponding cartesian coordinates are as follows (if you get the sothernmost instead of the northernmost point then swap the angles phi1 and phi2)<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xn = x1*cos(phi1) + x3*sin(phi1) (6)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>yn = y1*cos(phi1) + y3*sin(phi1)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>zn = z1*cos(phi1) + z3*sin(phi1)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xn = 0.2427036;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>yn = -0.3067243;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>zn = 0.9203343</b><br />
<br />
The corresponding polar coordinates are<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>bn = asin(zn) (7)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ln = atan2(yn,xn) (8)<span class="Apple-tab-span" style="white-space: pre;"> </span>(see note *1)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>bn = 66.975°;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ln = -51.64627°</b><br />
<span class="Apple-tab-span" style="white-space: pre;"> </span><br />
for phi1 (northernmost) and<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xs = x1*cos(phi2) + x3*sin(phi2) (6)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ys = y1*cos(phi2) + y3*sin(phi2)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>zs = z1*cos(phi2) + z3*sin(phi2)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xs = -0.2427036;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ys = 0.3067243;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>zs = -0.9203343</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>bs = asin(zs) (7)</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ls = atan2(ys,xs) (8)</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>bs = -66.975°;</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ls = 128.3537°</b><br />
<br />
for (southernmost) phi2.<br />
<br />
It is not necessary to calculate the coordinates of the second special point, because it is at the exact opposite side of the planet from the first one, so its Cartesian coordinates and its latitude are equal to those of the first point, times -1, and its longitude is 180° around the planet from the first special point.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifRt9m1RCK-oz99cy7NTuXVqGv9O4G5YUpUuHzWGi87QSsGdXhHzdX2ssvCd2gOubJJrscF14Cxso3I02zU4LVo0X6NaHNMNON-o-0T2LiSgQb4DJ6bBqbEp3pBwle1MB1Dwh2fGGUG8Mk/s1600/Gerardus_Mercator3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="889" data-original-width="832" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifRt9m1RCK-oz99cy7NTuXVqGv9O4G5YUpUuHzWGi87QSsGdXhHzdX2ssvCd2gOubJJrscF14Cxso3I02zU4LVo0X6NaHNMNON-o-0T2LiSgQb4DJ6bBqbEp3pBwle1MB1Dwh2fGGUG8Mk/s400/Gerardus_Mercator3.png" width="373" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 8. <span style="background-color: #f8f9fa; font-family: sans-serif; line-height: 21.28px;">Gerardus Mercator the creator of Mercator projection.</span></i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">["Gerardus Mercator (5 March 1512 – 2 December 1594) was a 16th-century <a href="https://en.wikipedia.org/wiki/Habsburg_Netherlands" target="_blank">German-Flemish</a> <a href="https://en.wikipedia.org/wiki/Cartographer" target="_blank">cartographer</a>, <a href="https://en.wikipedia.org/wiki/Geographer" target="_blank">geographer</a> and <a href="https://en.wikipedia.org/wiki/Cosmographer" target="_blank">cosmographer</a>. He was renowned for creating the <a href="https://en.wikipedia.org/wiki/Mercator_1569_world_map" target="_blank">1569 world map</a> based on a new <a href="https://en.wikipedia.org/wiki/Mercator_projection" target="_blank">projection</a> which represented sailing courses of constant bearing (<a href="https://en.wikipedia.org/wiki/Rhumb" target="_blank">rhumb lines</a>) as straight lines—an innovation that is still employed in nautical charts."]</span></i><br />
<h4>
The Equator Points of a Great Circle</h4>
Every great circle except for the equator intersects the equator in two points, called E1 and E2 in Figure 1. The longitudes of those points are 90° to the east and west of the northernmost and southernmost points of the great circle, of which the calculation is explained above.<br />
<br />
Calculate E1 as follows:<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi3 = phi1 + 90 = 120.624489505494680</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xe1 = x1*cos(phi3) + x3*sin(phi3)=-0.784194876815035</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ye1 = y1*cos(phi3) + y3*sin(phi3)=-0.620514621243571</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ze1 = z1*cos(phi3) + z3*sin(phi3) = 0</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>be1 = asin(ze1) = 0</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>le1 = atan2(ye1,xe1) = -141.646275410932280</b><br />
<br />
Calculate E2 as follows:<br />
<br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>phi4 = phi1 + 270 = 300.624489505494690</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>xe2 = x1*cos(phi4) + x3*sin(phi4) =0.784194876815035</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ye2 = y1*cos(phi4) + y3*sin(phi4) =0.620514621243571</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>ze2 = z1*cos(phi4) + z3*sin(phi4) =0</b><br />
<b><br /></b>
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>be2 = asin(ze2) = 0</b><br />
<b><span class="Apple-tab-span" style="white-space: pre;"> </span>le2 = atan2(ye2,xe2) = 38.353724589067724</b><br />
<br />
So, the great circle through Amsterdam and San Francisco crosses the equator at longitudes 38.3537° and -141.64627°, in Kenya and the Pacific Ocean, respectively.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaOo2E_d2xj0BqrTiRr-e8NWXaPwx0q395H5dU1ozJJTM_xKy3OCYwhiKrIXN7cAEMz1ICZyfNUBDOlX6o2ewSy8OihcoI7chfolCdeQ6XLdWuATIX1cB_WSdJ4DuyvoAvKLawWQ1cgNRo/s1600/Extreme_Points_Robinson.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="730" data-original-width="1388" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaOo2E_d2xj0BqrTiRr-e8NWXaPwx0q395H5dU1ozJJTM_xKy3OCYwhiKrIXN7cAEMz1ICZyfNUBDOlX6o2ewSy8OihcoI7chfolCdeQ6XLdWuATIX1cB_WSdJ4DuyvoAvKLawWQ1cgNRo/s400/Extreme_Points_Robinson.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 4. The extreme points (northernmost, southernmost, easternmost and westernmost) shown on Robinson projection. Notice how the great circle acts strange when behind the sphere.</i></span></td></tr>
</tbody></table>
<div>
<div>
<i><span style="color: #274e13;"><br /></span></i></div>
<div>
<i><span style="color: #274e13;">[Note *1: - The atan2(y,x) with two arguments means that you must make sure that the answer is in the right quadrant. The correct answer is either atan(y/x), or atan(y/x)+180°, and (in this case) you must select the solution that has x for its cosine and y for its sine (with the correct signs). Many computer languages and computer calculation programs have a two-argument version of the arc tangent function, and many calculators have a translation function from Cartesian to polar coordinates that you can use for this. For example xCalc for Windows can do all these calculations (download <a href="http://www.mnspoint.com/xCalc/" target="_blank">here</a>).]</span></i><br />
<br />
<h4>
Conclusions</h4>
</div>
<div>
It is interesting how some large maps give us wrong ideas. For example looking the following Mercator projection map would give you the idea that the Rhumb line from Amsterdam to San Francisco is the best when it actually is 1300 km longer than the Great circle.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYXO7JLRdb4XwGSCy_W7Qyt2wI8nukRNsDEGpKEkwRl3dfbbvd55-af7Ft9azqd-TRxRvaFgCwncddcRDkcFGriY_JB-qdc83PFJSb_3dFEtJ2yTETWDoA5ZQ5NwcMIVaFlg-v7j-oBoDy/s1600/Great_vs_Rhumb_line_3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="714" data-original-width="978" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYXO7JLRdb4XwGSCy_W7Qyt2wI8nukRNsDEGpKEkwRl3dfbbvd55-af7Ft9azqd-TRxRvaFgCwncddcRDkcFGriY_JB-qdc83PFJSb_3dFEtJ2yTETWDoA5ZQ5NwcMIVaFlg-v7j-oBoDy/s400/Great_vs_Rhumb_line_3.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 5. Rhumb line vs. Great circle on a Mercator projection map. The map gives us wrong ideas about the best route.</i></span></td></tr>
</tbody></table>
<div>
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<div>
AEA (Azimuthal Equal-Area) projection shows better great circles, like the following map.</div>
<div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKQaiMqqM4o2Axhm7n46TmI7GkEZ5HRcdWTx-vF40sLJVeFdmxQ2TtPUaKjnacR879hyphenhyphenKvR8KDqc_zpclCQa7VJt18DQFJ37q5GgW2121KnNNToC0yNAJagKOKSPxnARGrBRGnaPo12Qk3/s1600/Great_vs_Rhumb_line_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="607" data-original-width="916" height="265" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjKQaiMqqM4o2Axhm7n46TmI7GkEZ5HRcdWTx-vF40sLJVeFdmxQ2TtPUaKjnacR879hyphenhyphenKvR8KDqc_zpclCQa7VJt18DQFJ37q5GgW2121KnNNToC0yNAJagKOKSPxnARGrBRGnaPo12Qk3/s400/Great_vs_Rhumb_line_1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 6. Same data on AEA projection map. The map projection is somewhat more usable.</i></span></td></tr>
</tbody></table>
<div>
<br />
The only way to get any realistic view to large spherical matters is to look them on a ball.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTc5C2t-lKZFzT6JxJSaAbL40SJEyUCpXbCea36RbR2GH39w_IV5_fAAdFvE085E2zhi9oTWAuCczLA39g7lqTKBe_HF6Yj6n6hwpB0AjMhGk27ILKI8Y6TTkc58c1mGtE5XmmChWqH9Kl/s1600/View_ta_a_ball.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="502" data-original-width="516" height="387" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTc5C2t-lKZFzT6JxJSaAbL40SJEyUCpXbCea36RbR2GH39w_IV5_fAAdFvE085E2zhi9oTWAuCczLA39g7lqTKBe_HF6Yj6n6hwpB0AjMhGk27ILKI8Y6TTkc58c1mGtE5XmmChWqH9Kl/s400/View_ta_a_ball.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 7. The best representation of a sphere is a sphere (or a view to a sphere).</i></span></td></tr>
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<br /></div>
<div>
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<div>
<b><span style="color: #0c343d;">RESOURCES</span></b><br />
<b><span style="color: #0c343d;"><br /></span></b>
/1/ <a href="http://aa.quae.nl/en/index.html" target="_blank">Astronomy Answers by Dr Louis Strous</a><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKny1OROG_1FT8Vny-h0bXA0WURliAkF7adXtfrjM_KQtqfrZjZ34jgKl1VhN1xDtY6ba2Bx51hy1FIuC5rMAagRdPZrGwDP2Asg-lzNJgS8dWnBmXWtYEhoTJuxqflY0nDa4cDJ9Tq9vT/s1600/GreekAlphabet.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1236" data-original-width="1600" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiKny1OROG_1FT8Vny-h0bXA0WURliAkF7adXtfrjM_KQtqfrZjZ34jgKl1VhN1xDtY6ba2Bx51hy1FIuC5rMAagRdPZrGwDP2Asg-lzNJgS8dWnBmXWtYEhoTJuxqflY0nDa4cDJ9Tq9vT/s400/GreekAlphabet.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Greek alphabets.</i></span></td></tr>
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<div style="text-align: center;">
* * *</div>
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Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-17542542911370494932017-12-23T07:19:00.001+00:002017-12-26T05:50:36.056+00:00Certain Direction from a Point - (Part 2, Great Circles)Suppose you want to know where you go if you start from a particular town in a particular direction and keep going straight (along a great circle). You can calculate the coordinates of points along the route as follows:
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE6beLcILYK84ktTz5-kdL2M3ocq27W9NQOwmpJHoiXU91WAs0Eec9fTrvb2IQoNC_JYYJqZ5n3yu1jbjDLE9155PK2LMNSnKzbjuCE-1D2WyZh31RzRb5IBL6avVRAcyTvL7FGPqjl-a6/s1600/The+Hondius-Mercator+atlas.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1376" data-original-width="1600" height="343" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgE6beLcILYK84ktTz5-kdL2M3ocq27W9NQOwmpJHoiXU91WAs0Eec9fTrvb2IQoNC_JYYJqZ5n3yu1jbjDLE9155PK2LMNSnKzbjuCE-1D2WyZh31RzRb5IBL6avVRAcyTvL7FGPqjl-a6/s400/The+Hondius-Mercator+atlas.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i><span style="background-color: white; font-family: sans-serif; line-height: 17.8976px;">Fig. 2. Mercator and </span><span style="background-color: white; font-family: sans-serif; line-height: 17.8976px;">Hondius</span></i></span></td></tr>
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<a name='more'></a><i><span style="color: #274e13;">["Jodocus Hondius (<a href="https://en.wikipedia.org/wiki/Latin" target="_blank">Latinized</a> version of his <a href="https://en.wikipedia.org/wiki/Dutch_language" target="_blank">Dutch</a> name: Joost de Hondt) (14 October 1563 – 12 February 1612) was a <a href="https://en.wikipedia.org/wiki/Flemish_people" target="_blank">Flemish</a> <a href="https://en.wikipedia.org/wiki/Engraving" target="_blank">engraver</a> and <a href="https://en.wikipedia.org/wiki/Cartographer" target="_blank">cartographer</a>. He is sometimes called Jodocus Hondius the Elder to distinguish him from his son Jodocus Hondius II. Hondius is best known for his early maps of the <a href="https://en.wikipedia.org/wiki/New_World" target="_blank">New World</a> and <a href="https://en.wikipedia.org/wiki/Europe" target="_blank">Europe</a>, for re-establishing the reputation of the work of <a href="https://en.wikipedia.org/wiki/Gerardus_Mercator" target="_blank">Gerard Mercator</a>, and for his portraits of <a href="https://en.wikipedia.org/wiki/Francis_Drake" target="_blank">Francis Drake</a>. One of the notable representatives in the <a href="https://en.wikipedia.org/wiki/Golden_Age_of_Dutch_cartography" target="_blank">Golden Age of Dutch/ Netherlandish cartography</a>, he helped establish <a href="https://en.wikipedia.org/wiki/Amsterdam" target="_blank">Amsterdam</a> as the center of <a href="https://en.wikipedia.org/wiki/Cartography" target="_blank">cartography</a> in Europe in <a href="https://en.wikipedia.org/wiki/Dutch_Golden_Age" target="_blank">the 17th century</a>."]</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
Let's say you start from Amsterdam (52°22' north, 4°54' east) by going straight to the east, and you keep going straight. If you keep this up for 1000 km, then where are you? Most of calculation is similar to the part 1 of this article series.<br />
<br />
<b><span style="color: #4c1130;">1.</span></b> Call the polar coordinates (longitude and latitude) of the city l1 and b1, and the direction in which you start gamma, measured from south to west (so south = 0°, west = 90°, north = 180°, east = 270°).
<br />
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<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>l1 = 4.9°;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>b1 = 52.37°; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>gamma = 270°</b><br />
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<b><span style="color: #4c1130;">2</span></b>. Translate the polar coordinates of the city to the corresponding Cartesian coordinates x1, y1, z1 according to formulas 1-3 already shown in part 1.
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<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x1 = cos(l1)*cos(b1) (1)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y1 = sin(l1)*cos(b1) (2)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z1 = sin(b1) (3)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x1 = 0.6083285; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y1 = 0.05215215; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z1 = 0.7919701</b><br />
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<b><span style="color: #4c1130;">3. </span></b>Calculate the Cartesian coordinates of the corresponding south point with
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>lsouth = l1;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>bsouth = b1 - 90°</b><br />
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if b1 is positive (i.e., in the Northern hemisphere), and
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<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>lsouth = l1 + 180°;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>bsouth = -90° - b1</b><br />
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if b1 is negative (i.e., in the southern hemisphere).
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<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>xsouth = cos(lsouth)*cos(bsouth)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>ysouth = sin(lsouth)*cos(bsouth)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>zsouth = sin(bsouth)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>xsouth = 0.7890756; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>ysouth = 0.06764765; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>zsouth = -0.6105599</b><br />
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<b><span style="color: #4c1130;">4</span></b>. Calculate the cartesian coordinates of the corresponding west point with
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<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>lwest = l1 - 90°;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>bwest = 0.</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>xwest = cos(lwest)*cos(bwest)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>ywest = sin(lwest)*cos(bwest)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>zwest = sin(bwest)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>xwest = 0.08541692; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>ywest = -0.9963453; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>zwest = 0</b><br />
<b><span style="color: #4c1130;"><br /></span></b>
<b><span style="color: #4c1130;">5. </span></b>Calculate the cartesian coordinates x3, y3, z3 of the great circle point at 90° from the city:
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x3 = xsouth*cos(gamma) + xwest*sin(gamma) (10)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y3 = ysouth*cos(gamma) + ywest*sin(gamma)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z3 = zsouth*cos(gamma) + zwest*sin(gamma)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x3 = -0.08541692; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y3 = 0.9963453 ; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z3 = 0.0000000,</b><br />
<br />
<span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><b style="background-color: white; color: #121212; font-family: 'Trebuchet MS', Verdana, Arial, sans-serif; font-size: 12.61px; line-height: 18.915px;"> </b>(yielding P3:<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>l3 = 94.90000000;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>b3 = 0.00000000)</b><br />
<br />
so in this case each Cartesian coordinate of point 3 is the opposite of the corresponding coordinate of the west point, which was to be expected because we start out going straight to the east. And so P3 is the opposite point of Pwest.
<br />
<br />
The distance per degree u across the Earth sphere is equal to
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>u = r*pi/180, where r = 6378 km</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>u = 111.317 km/°</b><br />
<br />
or 111.317 km per degree. Since dist = 1000 km corresponds to an angle phi of
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>phi = dist/u</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>phi = 8.98335°</b><br />
<br />
we can now calculate the point in question.
<br />
<br />
<b><span style="color: #4c1130;">6.</span></b> Now use formulas 6, 7 and 8 (in part 1) to calculate the desired Cartesian and polar coordinates.
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x = x1*cos(phi) + x3*sin(phi) (6)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y = y1*cos(phi) + y3*sin(phi)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z = z1*cos(phi) + z3*sin(phi)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>x = 0.587529; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>y = 0.2070892; </b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>z = 0.7822556,</b><br />
<br />
and to polar coordinates
<br />
<br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>b = asin(z) (7)</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>l = atan2(y,x) (8)</b><br />
<b><br /></b>
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>b = 51.46756°;</b><br />
<b><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span><span style="background-color: white; color: #121212; font-family: "trebuchet ms" , "verdana" , "arial" , sans-serif; font-size: 12.61px; line-height: 18.915px;"> </span>l = 19.41627°.</b><br />
<br />
This is a location in the middle of Poland (see figure 1.)<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwl8lyHCwLZ_0zIoHOdRlJ35_WvJxMHHMkrGtYW5RNQ-FLqjZzibShyphenhyphenafuD73xS7TgvGV5MM96WGSubos-QqL5dTafds37cgeyZ8Kj9w77i9PxUcF4Ly250s7hcdKknU4ikTyqgArCa_dC/s1600/P_P3_Robinson.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="979" data-original-width="1191" height="328" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwl8lyHCwLZ_0zIoHOdRlJ35_WvJxMHHMkrGtYW5RNQ-FLqjZzibShyphenhyphenafuD73xS7TgvGV5MM96WGSubos-QqL5dTafds37cgeyZ8Kj9w77i9PxUcF4Ly250s7hcdKknU4ikTyqgArCa_dC/s400/P_P3_Robinson.png" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Fig. 1. 1000 km east from AMS(terdam) is in the middle of Poland (P) and the 90° point (P3) is somewhere in the Indian ocean. (Robinson projection)</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">RESOURCES
</span></b><br />
<br />
/1/ <a href="http://aa.quae.nl/en/index.html" target="_blank">Astronomy Answers by Dr Louis Strous</a><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-Hyri_MF7zt5njCo35KdKACle_2oY84uV3pimdGqljMOQkC9Zga_4g0gL6heOF18pmusMnpT6Dt5DnT40592f5v_Te534mCZTyWIDpH0xuGjmoKtHwKD66qwwnawR44Q2Xy_udDZHuIsd/s1600/GreekAlphabet.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1236" data-original-width="1600" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-Hyri_MF7zt5njCo35KdKACle_2oY84uV3pimdGqljMOQkC9Zga_4g0gL6heOF18pmusMnpT6Dt5DnT40592f5v_Te534mCZTyWIDpH0xuGjmoKtHwKD66qwwnawR44Q2Xy_udDZHuIsd/s400/GreekAlphabet.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Greek alphabets</i></span></td></tr>
</tbody></table>
<br />
<br />
<div style="text-align: center;">
* * *
</div>
<div style="text-align: center;">
<br /></div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-85818244386183921402017-12-19T23:20:00.000+00:002017-12-26T05:30:03.439+00:00Definition of a Great Circle - (Part 1, Great Circles)<i><span style="color: #274e13;">[Since great circle calculations are so important on all spheres (like Earth, planets, polar coordinates, etc.) I have to add here such a text. This follows mostly /1/] </span></i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUwhB9c0IIxhumb8cJ5yJ6BurUNUH9ITmdgE_TsJxwx-LYh-wyO_h-KBP_96KLLJVia3c8OJ10HobM9OHmN597Lbyx25yyzJsyRj3Fr-KWFgGK0gaXXaeOqb-j6AiFw04ssdQK4hhRB8uu/s1600/lookofmap_1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="387" data-original-width="250" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUwhB9c0IIxhumb8cJ5yJ6BurUNUH9ITmdgE_TsJxwx-LYh-wyO_h-KBP_96KLLJVia3c8OJ10HobM9OHmN597Lbyx25yyzJsyRj3Fr-KWFgGK0gaXXaeOqb-j6AiFw04ssdQK4hhRB8uu/s400/lookofmap_1.jpg" width="257" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 7. Arthur H. Robinson 1979</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">["Arthur H. Robinson (January 5, 1915 – October 10, 2004) was an American geographer and cartographer, who was professor in the Geography Department at the University of Wisconsin–Madison from 1947 until he retired in 1980. He was a prolific writer and influential philosopher on cartography.<br /><br /> One of Robinson's most notable accomplishments is the <a href="https://en.wikipedia.org/wiki/Robinson_projection" target="_blank">Robinson projection</a>. In 1961, Rand McNally asked Robinson to choose a projection for use as a world map that, among other criteria, was uninterrupted,[9] had limited distortion, and was pleasing to the eye of general viewers.[10] Robinson could not find a projection that satisfied the criteria, so Rand McNally commissioned him to design one.<br /><br /> Robinson proceeded through an iterative process to create a pseudo-cylindrical projection that intends to strike a compromise between distortions in areas and in distances, in order to attain a more natural visualization. The projection has been widely used since its introduction. In 1988, National Geographic adopted it for their world maps but replaced it in 1998 with the <a href="https://en.wikipedia.org/wiki/Winkel_tripel_projection" target="_blank">Winkel tripel</a> projection."]</span></i><br />
<a name='more'></a><br />
<br />
<span style="font-size: large;">A Great Circle</span><br />
<br />
A <a href="https://en.wikipedia.org/wiki/Great_circle" target="_blank">great circle</a> is the largest circle you can draw on a
sphere, the equator for example. It is a special circle at
the surface of a sphere (for example of a planet or of the
sky).
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3TYylXj3mna2ABOfblbyKsTYMlifs_-PdX6qPAiKiIyo5TShWA9p6dVqCH060gHSmnUFUemN2nAP4csWC7IwbwzeHqi_eUprFJa1tXcwUclN-oFJVq8RCjOuyd4Dh7NX-K0KXpgCu8K8h/s1600/Figure_2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3TYylXj3mna2ABOfblbyKsTYMlifs_-PdX6qPAiKiIyo5TShWA9p6dVqCH060gHSmnUFUemN2nAP4csWC7IwbwzeHqi_eUprFJa1tXcwUclN-oFJVq8RCjOuyd4Dh7NX-K0KXpgCu8K8h/s400/Figure_2.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Fig. 1: Drawing of a Great Circle on a Sphere</i></td></tr>
</tbody></table>
<br />
Figure 1 shows great circle G and latitude circle B on
a sphere. You can recognize a great circle by any of the
following attributes:<br />
<ul>
<li>A great circle's center is always also the center of
the sphere. All great circles meet at the center of
the sphere.</li>
<li>A great circle divides the surface of a sphere in
two exactly equal size parts.</li>
<li>A great circle is the largest circle that fits on
the sphere.</li>
<li>If you keep going straight across a sphere then you
go along a great circle.</li>
<li>The shortest route between two points, measured
across the sphere, is part of a great circle.</li>
</ul>
All meridians are great circles. Latitude circles other than
the equator (for example circle B in the picture) are not
great circles, for example because they are smaller than the
equator, which is a great circle.<br />
<br />
A great circle provides the shortest route if you travel at
a fixed speed compared to the ground, and also
(approximately) if your speed, though not fixed, is always
much smaller than the rotation speed of the sphere at its
equator. This does not hold, for example, for things that
orbit around the Earth outside the atmosphere.
<br />
<br />
For example an airplane will always use least energy between
two points if it follows the great circle between these two
points what ever the winds might be. A sail ship might
sometimes be a different question since it uses its keel but
usually not.
<br />
<br />
<i><span style="color: #274e13;">[If you wish to verify the following calculations use <a href="http://www.mnspoint.com/xCalc/" target="_blank">xCalc</a> for example to do it (it is a free application which can be used to calculate formulas in Windows)]</span></i><br />
<br />
<br />
<span style="font-size: large;">Find a Great Circle Through Two Known Points
</span><br />
<br />
Suppose that you want to draw the shortest route on a map
between a city P1 and a far-away other city P2, and you know
the geographical longitude and latitude of both cities.
Then, you can calculate the coordinates of points on that
route as follows.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUs0-OZiIrURutaopoQQNJUAWFrPmb8eMgKPsO-sKtA1PjvQlQid8qLHP-hroSSfZO09w8s3PzWEIbw2dMSR7E6EjOWqX8udX6bmA4mnw701ljxn6ce-aPA2f8_bO0btw9sfBj1AfXPtFy/s1600/Figure_4.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUs0-OZiIrURutaopoQQNJUAWFrPmb8eMgKPsO-sKtA1PjvQlQid8qLHP-hroSSfZO09w8s3PzWEIbw2dMSR7E6EjOWqX8udX6bmA4mnw701ljxn6ce-aPA2f8_bO0btw9sfBj1AfXPtFy/s400/Figure_4.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 4: Great Circle Through Amsterdam P1 and San Francisco P2</i></span></td></tr>
</tbody></table>
<br />
For example (Figure 4): Which point lies 1000 km from
Amsterdam (P1, 52°22' North, 4°54' East) on the shortest
route to San Francisco (P2, 37°46' North, 122°25' West),
assuming that the Earth is a sphere with a radius of 6378
km?<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEKAz-UmFr_RtVz7cUC4uZvw38869tFZSCEi2z9_rYcs9Gr_U465CrVarJ8JFpbt_jmpuCKqyk8Fd3XH5GKbFb9JT_zDliBypBAtI2JdMWf_A6fTLAW2tLLiUaC9_7PnG4ta7azfcrkfKX/s1600/815559+%25281%2529.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="478" data-original-width="640" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEKAz-UmFr_RtVz7cUC4uZvw38869tFZSCEi2z9_rYcs9Gr_U465CrVarJ8JFpbt_jmpuCKqyk8Fd3XH5GKbFb9JT_zDliBypBAtI2JdMWf_A6fTLAW2tLLiUaC9_7PnG4ta7azfcrkfKX/s400/815559+%25281%2529.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 6. Great Circle arc from Amsterdam to San Francisco</i></span></td></tr>
</tbody></table>
<br />
<span style="color: #4c1130;"><b>1.</b></span> Call the polar coordinates (longitude and latitude) of
the first city l1 and b1, and those of the second city l2
and b2.
<br />
<br />
<b> l1 = 4.9°; b1 = 52.37°; </b><br />
<b> l2 = -122.42°; b2 = 37.77°
</b><br />
<br />
<b><span style="color: #741b47;">2. </span></b>Translate the polar coordinates of the first city P1 to
the corresponding Cartesian coordinates x1, y1, z1 on a <a href="https://en.wikipedia.org/wiki/Unit_sphere" target="_blank">unit sphere</a> (see
Figure 2):
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivlzKmiaSRVAHkPHbv3yuoAMNDB81XtslcEp_KiOgAGHK1ou8ISVFRvMvcfyyVAhaXCHpQUe6eV0ONKL1qM0VqKj2sx6Ub1RYWdUMdPOJXN290TU0doNN964nMb4Za-JqYOOF_O4W2LGlQ/s1600/Figure_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivlzKmiaSRVAHkPHbv3yuoAMNDB81XtslcEp_KiOgAGHK1ou8ISVFRvMvcfyyVAhaXCHpQUe6eV0ONKL1qM0VqKj2sx6Ub1RYWdUMdPOJXN290TU0doNN964nMb4Za-JqYOOF_O4W2LGlQ/s400/Figure_1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Fig. 2: Illustration of Transformation from Polar to Cartesian Coordinates</i></td></tr>
</tbody></table>
<br />
<b> x1 = cos(l1)*cos(b1) (1)</b><br />
<b> y1 = sin(l1)*cos(b1) (2)</b><br />
<b> z1 = sin(b1) (3)</b><br />
<b><br /></b>
<b> x1=0.6083285;</b><br />
<b> y1=0.05215215;</b><br />
<b> z1=0.7919701;</b><br />
<br />
and similarly for the second city P2.<br />
<br />
<b>x2 = cos(l2)*cos(b2)</b><br />
<b> y2 = sin(l2)*cos(b2)</b><br />
<b> z2 = sin(b2)</b><br />
<b><br /></b>
<b> x2 = -0.423791;</b><br />
<b> y2 = -0.6672729;</b><br />
<b> z2 = 0.6124933</b><br />
<br />
<b><span style="color: #741b47;">3.</span></b> Calculate the angular distance psi between the two
cities, as seen from the center of the Earth (see Figure 3):
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvzczim6PYdaL7bGJFd8-KcImO4i5LtTqy8qylnSfXztaJmyTbkq7Ee9sVMpfCH9XDGRLnwI6bd60zzzLwMLWyGv3CmD4AMjexh0OScHh-JUH3gAsHHrEubsCNgLegzn_P29FzRrBsLaUd/s1600/Figure_3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="440" data-original-width="440" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvzczim6PYdaL7bGJFd8-KcImO4i5LtTqy8qylnSfXztaJmyTbkq7Ee9sVMpfCH9XDGRLnwI6bd60zzzLwMLWyGv3CmD4AMjexh0OScHh-JUH3gAsHHrEubsCNgLegzn_P29FzRrBsLaUd/s400/Figure_3.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 3: Illustration of the Angular Distance Between P1 and P2</i></span></td></tr>
</tbody></table>
<br />
<b>psi = acos(x1*x2 + y1*y2 + z1*z2) (4)</b><br />
<b> psi = 78.90289°</b><br />
<br />
The distance per degree u across the sphere is equal to
<br />
<br />
<b>u = r*pi/180, where r = 6378 km</b><br />
<b> u = 111.317 km/°</b><br />
<br />
so on Earth this is 111.317 km per degree. So San Francisco
is
<br />
<br />
<b>d = psi*u</b><br />
<b> d = 78.90289*111.317 = 8783 km</b><br />
<br />
from Amsterdam.
<br />
<br />
<b><span style="color: #741b47;">4.</span></b> To define the great circle for the purpose of other
calculations calculate the coordinates of the point P3 on
the great circle that is 90° from the first city P1 in the
direction of the second city P2 (see Figure 3):
<br />
<br />
<b>x3 = (x2 - x1*cos(psi))/sin(psi) (5)</b><br />
<b> y3 = (y2 - y1*cos(psi))/sin(psi)</b><br />
<b> z3 = (z2 - z1*cos(psi))/sin(psi)</b><br />
<b><br /></b>
<b> x3 = -0.5511833;</b><br />
<b> y3 = -0.6902162;</b><br />
<b> z3 = 0.4688268.</b><br />
<br />
This corresponds to
<br />
<br />
<b>b3 = asin(z3) = 27.95817°;</b><br />
<b> l3 = atan2(y3,x3) = -128.6097°, (see note *1)</b><br />
<br />
which is a location in the Eastern Pacific Ocean, to the
West of Mexico.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9iNdkPT2vn-kxTrb-WcT7MdQ5F1WFdYrvnpqzNOpnqOplLfRSbWYR0hiEw7-69d6IKtfq7FlLP6E78g1s74RqEWOtcFa0ChOAaaBWcmhc17UtzoMG8RGEbY4jvp_rPd3oz0MZKpRWci7E/s1600/P3_Robinson.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="483" data-original-width="993" height="193" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi9iNdkPT2vn-kxTrb-WcT7MdQ5F1WFdYrvnpqzNOpnqOplLfRSbWYR0hiEw7-69d6IKtfq7FlLP6E78g1s74RqEWOtcFa0ChOAaaBWcmhc17UtzoMG8RGEbY4jvp_rPd3oz0MZKpRWci7E/s400/P3_Robinson.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 6. P3 is located west of Mexico (Robinson projection).</i></span></td></tr>
</tbody></table>
<br />
<b><span style="color: #741b47;">5. </span></b>Since dist=1000 km corresponds to an angle phi of
<br />
<br />
<b>phi = dist/u</b><br />
<b> phi = 8.98335°</b><br />
<br />
we can now calculate the point in question.
<br />
<br />
The cartesian coordinates of the points of the great
circle are then, as a function of the angular distance phi
from the first city:
<br />
<br />
<b>x = x1*cos(phi) + x3*sin(phi) (6)</b><br />
<b> y = y1*cos(phi) + y3*sin(phi)</b><br />
<b> z = z1*cos(phi) + z3*sin(phi)</b><br />
<b><br /></b>
<b> x = 0.5148008;</b><br />
<b> y = -0.05626304;</b><br />
<b> z = 0.8554617.</b><br />
<br />
If phi = 0, then you are in the first city (Amsterdam). If
phi = psi, then you are in the second city (San Francisco).
If phi = 8.98335° we are 1000 km from the first point
towards the second point. If phi = 90° then we are at the P3
which defines our great circle in this question.
<br />
<br />
<b><span style="color: #741b47;">6.</span></b> You can now translate the Cartesian coordinates x, y, z
to polar coordinates l, b:
<br />
<br />
<b>b = asin(z) (7)</b><br />
<b> l = atan2(y,x) (8)</b><br />
<b><br /></b>
<b> b = 58.81077°;</b><br />
<b> l = -6.237153°.</b><br />
<br />
This is a location just to the North of Scotland.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwFl9bELa-afsnibDcHOJ0siSf6BHk8HMhdseV6c-sYCBjw746Eh6YzhYQzR_SvJd_-_mT9mrg5dWnt-jUKjiwD6T0YhoZmbt33gX6aVCCj4k_ISRYs5_nQEbwS3ZAqug27rtHeO3yZem/s1600/Result_Robinson.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="673" data-original-width="993" height="270" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwwFl9bELa-afsnibDcHOJ0siSf6BHk8HMhdseV6c-sYCBjw746Eh6YzhYQzR_SvJd_-_mT9mrg5dWnt-jUKjiwD6T0YhoZmbt33gX6aVCCj4k_ISRYs5_nQEbwS3ZAqug27rtHeO3yZem/s400/Result_Robinson.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig 5. Result P is located north of Scotland on a Robinson projection. Notice how all map projections distort long great circle arcs. If your distance is longer than 500 km it is a very good idea to check if the shortest distance line is any close to a line at all. The above curve is the shortest way from Amsterdam to San Francisco and to do it you have to fly over Greenland.</i></span></td></tr>
</tbody></table>
<i><span style="color: #274e13;">[<b>Note *1</b>:</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The atan2(y,x) with two arguments means that you
must make sure that the answer is in the right
quadrant. The correct answer is either atan(y/x), or
atan(y/x)+180°, and (in this case) you must select
the solution that has x for its cosine and y for its
sine (with the correct signs).
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Many computer languages and computer calculation
programs have a two-argument version of the arc
tangent function, and many calculators have a
translation function from cartesian to polar
coordinates that you can use for this. For example
xCalc for Windows can do all these calculations
(download <a href="http://www.mnspoint.com/xCalc/" target="_blank">here</a>).]</span></i><br />
<br />
<br />
<b><span style="color: #274e13;">Alternative</span></b><br />
<br />
There is an alternative for formula 6, which does not
require the calculation of the position of point 3:
<br />
<br />
<b> x = (x1*sin(psi-phi) + x2*sin(phi)) / sin(psi) (9)</b><br />
<b> =0.514800782206212</b><br />
<b> y = (y1*sin(psi-phi) + y2*sin(phi)) / sin(psi)</b><br />
<b> =-0.056262996832530</b><br />
<b> z = (z1*sin(psi-phi) + z2*sin(phi)) / sin(psi)</b><br />
<b> =0.855461647198339</b><br />
<br />
<br />
However, point P3 is necessary if you want to know other
things about the great circle, as you'll see in the
following parts of this text.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilquosSPyHSTF_C1H_qH056DnS3062Q_l5tpMvWxGzZyUV3c660YRgszolbrwBoSkW2LMY07fNKn2EBOXHUR8dpWBYcE2Jzss5VpbB5xiDmxj9ukXbLMru8YKnZpMJycn1P-pIgWuGGnFW/s1600/FDR-big-globe.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1280" data-original-width="947" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEilquosSPyHSTF_C1H_qH056DnS3062Q_l5tpMvWxGzZyUV3c660YRgszolbrwBoSkW2LMY07fNKn2EBOXHUR8dpWBYcE2Jzss5VpbB5xiDmxj9ukXbLMru8YKnZpMJycn1P-pIgWuGGnFW/s400/FDR-big-globe.jpg" width="295" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Fig. 8. F. D. Roosevelt's giant 50-inch globe, which is on floor beside his desk.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #274e13;">RESOURCES
</span></b><br />
<br />
/1/ <a href="http://aa.quae.nl/en/index.html" target="_blank">Astronomy Answers by Dr Louis Strous</a><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj17xaFRafkZRsYqQ217m8ri96Bh7qfEDCiw6fnRTTev8q6cwFleONC-y1D1-EtHGNe2z0FUseviNjeaRMFwN8np8R8Y74xPRRv7eSkW0bDSORpRQWghjsQObqZK5u8wqBaiW5HNa32aFjm/s1600/GreekAlphabet.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1236" data-original-width="1600" height="308" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj17xaFRafkZRsYqQ217m8ri96Bh7qfEDCiw6fnRTTev8q6cwFleONC-y1D1-EtHGNe2z0FUseviNjeaRMFwN8np8R8Y74xPRRv7eSkW0bDSORpRQWghjsQObqZK5u8wqBaiW5HNa32aFjm/s400/GreekAlphabet.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="background-color: white; color: #cc0000; font-family: 'trebuchet ms', verdana, arial, sans-serif; font-size: 12.8px; line-height: 18.915px;"><span style="font-size: small;">Greek alphabet chart.</span></i></td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
* * *
</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-56732249184522823232017-12-15T18:55:00.000+00:002017-12-15T19:01:53.960+00:00Mars Atmosphere and WaterThere seems to be often a discussion about the Martian atmosphere and water there. But it is not commonly understood what effects the low pressure has to water on Mars (and generally in space). Most of us have done some water chemistry in schools and it is usually known how water reacts to pressure and temperature so that it is either solid, liquid or vapor and that there exists so called triple point where all these phases meet. The following figure shows the general water phase diagram relative to the pressure and temperature.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglh4Ml7I6F-5zY97HORsibBQKQM0TsI1iSTTZ21CirQgPYWV2_YMm6cvroBBzKChIt_6LPYUWOK0ioaMh3BUE9B6eqCcmJl0IoLOO1j4ZFpo0b4OzTqO8fI_OLf7wqFd37C1wL3hBgq6J4/s1600/700px-Phase_diagram_of_water.svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="591" data-original-width="700" height="337" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglh4Ml7I6F-5zY97HORsibBQKQM0TsI1iSTTZ21CirQgPYWV2_YMm6cvroBBzKChIt_6LPYUWOK0ioaMh3BUE9B6eqCcmJl0IoLOO1j4ZFpo0b4OzTqO8fI_OLf7wqFd37C1wL3hBgq6J4/s400/700px-Phase_diagram_of_water.svg.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 1. <a href="https://en.wikipedia.org/wiki/Water_(data_page)#Phase_diagram" target="_blank">Water Phase Diagram</a></i></span></td></tr>
</tbody></table>
<br />
In this diagram we can see that as the pressure gets lower we come to the triple point below which there is no more any liquid water available. In space where there is the zero pressure there is no liquid water possible, it boils instantly. Only solid and vapor is possible.<br />
<br />
Since in any atmosphere (Earth and Mars) the pressure gets lower when we go higher it is more convenient to show this diagram inverted so that it shows the phenomena relative to the altitude. Below is such a diagram drawn for Earth or Mars.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4fAWENzoExeqyux_UAu-lYAhretGoT-YF5QA8bDPHxaNbQDQoqjyIsoRdXWMHHZTs_KAHyZz0MGFkUCq9YsIm4yMNCZoGVCvlQADMlFsHtD0UB-dS3bK_shYB537YdpncSJcPzlISWoKM/s1600/Elevation_Phase_diagram_of_water.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="498" data-original-width="807" height="246" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4fAWENzoExeqyux_UAu-lYAhretGoT-YF5QA8bDPHxaNbQDQoqjyIsoRdXWMHHZTs_KAHyZz0MGFkUCq9YsIm4yMNCZoGVCvlQADMlFsHtD0UB-dS3bK_shYB537YdpncSJcPzlISWoKM/s400/Elevation_Phase_diagram_of_water.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 2. Water Phase Diagram on Earth and Mars</i></span></td></tr>
</tbody></table>
<br />
In this diagram we can see on the left the "normal" situation on Earth (the space might be the more general situation). And we are very used to liquid water since it exists between 0 and 100 C degrees, and is the most common water phase here on Earth. But we seem to forget that Earth surface is just a small exception in the huge space.<br />
<br />
When we move to the Mars (on the right in the diagram) we instantly notice that we have lost our liquid water since Mars mean surface pressure is almost exactly water's triple point. And that we cannot even find any liquid water if we go higher in the atmosphere since the pressure just gets lower. Also if we consider the typical low temperatures on Mars we see that any liquid water would be very rare there. Also if the typical liquid water range here on Earth is 0 to 100 C degrees, on Mars it might be just 5 C degrees in very low places and high Mars temperatures. So it is rather clear why there is no living plants possible on Mars without heated pressurized shelters.<br />
<br />
In this diagram we can also see that the mean Mars surface is at about 35 km altitude compared to the Earth's atmosphere and we also know that nothing much usually lives naturally above 6 km here on Earth, top of the <a href="https://en.wikipedia.org/wiki/Mount_Everest#Flora_and_fauna" target="_blank">Mount Everest</a> for example.<br />
<br />
<i><span style="color: #0c343d;">["There is very little native flora or fauna on Everest. There is a moss that grows at 6,480 metres (21,260 ft) on Mount Everest. It may be the highest altitude plant species. An alpine cushion plant called Arenaria is known to grow below 5,500 metres (18,000 ft) in the region"]
</span></i><br />
<i><span style="color: #0c343d;"><br /></span></i>
<i><span style="color: #0c343d;"><br /></span></i>
<b><span style="color: #0c343d;">VIDEOS</span></b><br />
<br />
YouTube video: <a href="https://youtu.be/XoOQNwcrDWE" target="_blank">"Water Boiling at Room Temperatures, Under a Vacuum"</a><br />
<br />
<br />
<div style="text-align: center;">
* * *</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-69017930836912932192017-10-24T22:05:00.001+01:002017-10-24T22:08:06.735+01:00Apollo Mission Films (Part 14, Apollo Control Systems)NASA made several films during the Apollo program about the physics, calculations and programming principles used to do the manned Moon trip. Compared to today's standards many of those are very detailed and give very good information about how the programs behind the successful missions were tailored. Most of films originated from MSC (Manned Spacecraft Center) Houston, Texas. This is a list of links I have found in YouTube (there might be more in various archives).<br />
<br />
<a name='more'></a><br />
<br />
<span style="font-size: large;">Manned Spacecraft Center (Houston Texas) introductory films
</span><br />
<br />
"NASA Manned Spacecraft Center - A National Resource - 1960's Film"<br />
<a href="https://www.youtube.com/watch?v=cf7VkaL8TC0" target="_blank">https://www.youtube.com/watch?v=cf7VkaL8TC0</a><br />
<br />
<span style="font-size: large;">General films about the mission, propulsion/power and computers
</span><br />
<br />
"Project Apollo: Manned Flight to the Moon 1963 NASA Animation"<br />
<a href="https://www.youtube.com/watch?v=0f8CfCxr7M8" target="_blank">https://www.youtube.com/watch?v=0f8CfCxr7M8</a><br />
<br />
"Apollo Lunar Mission - NASA 1967 Film"<br />
<a href="https://www.youtube.com/watch?v=AVtD_lZp6eM" target="_blank">https://www.youtube.com/watch?v=AVtD_lZp6eM</a><br />
<br />
"Spacecraft Propulsion and Power - NASA 1965 Film"<br />
<a href="https://www.youtube.com/watch?v=jOZutEFXuLo" target="_blank">https://www.youtube.com/watch?v=jOZutEFXuLo</a><br />
<br />
"The Computer And Manned Space Flight - 1960's NASA Educational Documentary"<br />
<a href="https://www.youtube.com/watch?v=oJPLVa7q410" target="_blank">https://www.youtube.com/watch?v=oJPLVa7q410</a><br />
<br />
<span style="font-size: large;">Detailed films about the various mission phases
</span><br />
<br />
"Project Apollo Mission Planning: "Fly Me to the Moon--And Back" 1966 NASA MPAD"<br />
<a href="https://www.youtube.com/watch?v=lEgA16upX9c" target="_blank">https://www.youtube.com/watch?v=lEgA16upX9c</a><br />
<br />
"Launch Windows for Lunar Landing - NASA/MSC 1967 Film"<br />
<a href="https://www.youtube.com/watch?v=SE9hJHICJv4" target="_blank">https://www.youtube.com/watch?v=SE9hJHICJv4</a><br />
<br />
"The Lunar Landing - NASA MPAD 1968 Film"<br />
<a href="https://www.youtube.com/watch?v=tRSJkHds9BY" target="_blank">https://www.youtube.com/watch?v=tRSJkHds9BY</a><br />
<br />
"Project Apollo: "Lunar Orbit Rendezvous" 1968 NASA Mission Planning and Analysis Division"<br />
<a href="https://www.youtube.com/watch?v=UOnKHX1p8s4" target="_blank">https://www.youtube.com/watch?v=UOnKHX1p8s4</a><br />
<br />
"Apollo Atmospheric Entry Phases - 1968 NASA Educational Documentary"<br />
<a href="https://www.youtube.com/watch?v=IATIU6ZhiOI" target="_blank">https://www.youtube.com/watch?v=IATIU6ZhiOI</a><br />
<br />
<div style="text-align: center;">
* * *
</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-42329124429006296822017-07-25T04:07:00.000+01:002017-07-26T00:35:10.261+01:001950's Computer Language "George"<i><span style="color: #274e13;">[<a href="https://en.wikipedia.org/wiki/Laning_and_Zierler_system" target="_blank">The Laning and Zierler system</a> (sometimes called "George" by
its users) was one of the first operating algebraic systems,
that is, a system capable of accepting mathematical formulae
in algebraic notation and executing equivalent machine code.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The system accepted formulas in a more or less algebraic
notation. It respected the standard rules for operator
precedence, allowed nested parentheses, and used
superscripts to indicate exponents.
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">It was among the first programming systems to allow symbolic
variable names and allocate storage automatically. The
system also automated the following tasks: floating point
computation, linkage to subroutines for the basic functions
of analysis (sine, etc.) and printing, and arrays and
indexing. It could also solve automatically ordinary
differential equations using Gills' variation of the 4th
order <a href="https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods" target="_blank">Runge-Kutta Method</a>, that was an inbuilt language
feature.
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFHuEUFoztSJH3vJ4keOYsJUz7wwbPWiN5o9EXwf5gL_cXE9PyCU4A7Yb_xqp3LfUR6dzDGEmlKKL_8he6FGZnYNyZyiJ34t38fRPb_S8Czd0Lu03VOcI3uy0MKadd5iqOcnN4r_eBKAs1/s1600/zds4iozkeso4mtwoumbo.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="182" data-original-width="175" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFHuEUFoztSJH3vJ4keOYsJUz7wwbPWiN5o9EXwf5gL_cXE9PyCU4A7Yb_xqp3LfUR6dzDGEmlKKL_8he6FGZnYNyZyiJ34t38fRPb_S8Czd0Lu03VOcI3uy0MKadd5iqOcnN4r_eBKAs1/s320/zds4iozkeso4mtwoumbo.jpg" width="307" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium; text-align: start;">Dr. J. Halcombe Laning</i></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">It was implemented in 1952-53 and published in 1954 for the
<a href="https://en.wikipedia.org/wiki/Whirlwind_I" target="_blank">MIT WHIRLWIND computer</a> by <a href="https://en.wikipedia.org/wiki/J._Halcombe_Laning" target="_blank">J. Halcombe Laning</a> and Neal Zierler. It was
made during a time with similar <a href="https://en.wikipedia.org/wiki/A-0_System" target="_blank">UNIVAC A-2</a>, <a href="https://en.wikipedia.org/wiki/Speedcoding" target="_blank">IBM Speedcoding</a>
and a number of other systems that were proposed but never
implemented.
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The following text is a reprint of a MIT's summer session report 1954.]</span></i><br />
<br />
<a name='more'></a><br />
<span style="font-size: large;">The Algebraic Coding System of Laning and Zierler ("George")
/1/
</span><br />
<br />
<br />
<b><span style="color: #0c343d;">I. Introduction
</span></b><br />
<br />
"The Automatic Coding System to be described was developed in 1952 and 1953 by J. H. Laning and H. Zier1er of the M.I.T. Instrumentation Laboratory. The translation and interpretation of the algebraic coding is realized in the M.I.T. Whirlwind Computer.
<br />
<br />
<i><span style="color: #741b47;">[The Whirlwind computer was developed at 211 Massachusetts Avenue by the Massachusetts Institute of Technology. It was the first real-time high-speed digital computer using random-access magnetic-core memory. Whirlwind featured among others outputs displayed on a CRT, and a light pen to write data on the screen.]
</span></i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikv8lcGiVStBKh7GGrsMbsqZ6TzCkBz9y6dNKxZEui1bD2ekUKbyridzt6NAcfwKYqP7YR51NBWoWS8CRq4YAaftPys5aL9JZ5dyr-xTmLkUwNtZ3FTYQHVc32GZbJJodCfFwG-OBkNNMj/s1600/Whirlwind_thfb301.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1031" data-original-width="1500" height="273" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikv8lcGiVStBKh7GGrsMbsqZ6TzCkBz9y6dNKxZEui1bD2ekUKbyridzt6NAcfwKYqP7YR51NBWoWS8CRq4YAaftPys5aL9JZ5dyr-xTmLkUwNtZ3FTYQHVc32GZbJJodCfFwG-OBkNNMj/s400/Whirlwind_thfb301.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 1. 1947 - MIT's Barta Building, Cambridge, MA, was the original home for Project Whirlwind. The computer occupied 2,500 square feet on the second floor. Photo courtesy MITRE Corporation.</i></span></span></td></tr>
</tbody></table>
<br />
The coder specifics his problem as a series of mathematical equations and other special symbols. From this manuscript a Flexo tape is punched, which constitutes the input to the computer.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhtKn-AjCoSBZBtsOfWaCKLn_edCxjE3hFdmUIagihQNP_FQmsFdG7A1qlkzO7RccMpPnS0fYhxSpSHyBLWWeRP16zIOi647S9LmRnC8vIM7JJr9T4PCIb-qlnyWA6MXRJUcndHJecdQ0y/s1600/flexowriter.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="458" data-original-width="487" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhtKn-AjCoSBZBtsOfWaCKLn_edCxjE3hFdmUIagihQNP_FQmsFdG7A1qlkzO7RccMpPnS0fYhxSpSHyBLWWeRP16zIOi647S9LmRnC8vIM7JJr9T4PCIb-qlnyWA6MXRJUcndHJecdQ0y/s320/flexowriter.gif" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 2. Friden Flexowriter, model SFD.</i></span></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #741b47;">[Friden Flexowriter, model SFD, was used with the early computers. Though it was improbably heavy and made the noise of a machine gun, it had about the same functionality as the well-known Teletype ASR33 teleprinter. Usually it was never used on-line. Rather the user would carry his prepared lengths of paper tape on bicycle to the computer centre vice versa. The Flexowriter, originally a pre_WWII IBM development, was manufactured in Nijmegen, The Netherlands, from (about) 1955 to 1965.]</span></i><br />
<br />
The Flexo characters are translated into Whirlwind instructions which are then carried out. The results requested by the programmer are presented in typewritten form. All arithmetic operations are carried out in floating point using a so called (240, 6) system. Numbers may range up to 10^19 with a precision of about 7.2 decimal digits."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYScHMAV9ar5me8SWttI6WCh6qgLx6yq0E2F6sp9qb6wgJ9OzSs_cG7WqW3lMBXGh9QNMIjX76_wHodo86jTBpAeGUNoQvYRCpkBAsxspcck4dEl4Nb8JUl5uWV4qEWaCfxPYlfnAGpxrm/s1600/Whirlwind_thf5001.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1189" data-original-width="1500" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYScHMAV9ar5me8SWttI6WCh6qgLx6yq0E2F6sp9qb6wgJ9OzSs_cG7WqW3lMBXGh9QNMIjX76_wHodo86jTBpAeGUNoQvYRCpkBAsxspcck4dEl4Nb8JUl5uWV4qEWaCfxPYlfnAGpxrm/s400/Whirlwind_thf5001.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="text-align: center;">
<span style="color: #cc0000; font-size: small;"><i>Figure 3. 1950 - Stephen Dodd, Jay Forrester, Robert Everett, and Ramona Ferenz at Whirlwind I test control in the Barta Building.</i></span></div>
<div>
<br /></div>
</td></tr>
</tbody></table>
<br />
<b><span style="color: #0c343d;">II. Basic Operations</span></b><br />
<br />
"All of the lower case letters may be used as variables, and
equations of the following form are used.
<br />
<br />
<br />
<pre><span style="font-size: large;"> a=5,
y=-6.3a,
b=O.0053(a-y)/2ay,
n=n+2,
w=-w,
x=a(b+c(d-e)),
z=r+2s/t+u,</span>
</pre>
<br />
<br />
A comma terminates all equations. Plus and minus signs
slashes and parentheses, have their usual mathematical
significance. No more than 4 parentheses may be open at any
one time. Plus and minus signs separate terms so that the
last equation above is the same as
<br />
<br />
<br />
<pre><span style="font-size: large;"> z=r+(2s/t)+u,
</span></pre>
<br />
<br />
Exponents: Upper case numbers on the MIT Flexowriters
appear as exponents; (in this text upper case 2 is written
as ^2 since upper case numbers are not available here) there
is also an upper case minus sign, but no upper case plus
sign. The following are interpreted correctly."<br />
<br />
<br />
<pre><span style="font-size: large;"> a=5^2,
b=(a-2)^-2,
c=(a+b)^2/a^-3,</span>
</pre>
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp2SyR20BrStIOeo2UFshK4L27nrhZ-xL5nz_urIisr2IOYfDo0E3zcXXwiYUNOz_yrOuOJzTTcUBymzDTuagk0eh3A-v9afGrB1jKqJYVZI099wZDaa3rgsygXgGuh4EE87EPL_qc1bzY/s1600/pt1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="450" data-original-width="600" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhp2SyR20BrStIOeo2UFshK4L27nrhZ-xL5nz_urIisr2IOYfDo0E3zcXXwiYUNOz_yrOuOJzTTcUBymzDTuagk0eh3A-v9afGrB1jKqJYVZI099wZDaa3rgsygXgGuh4EE87EPL_qc1bzY/s400/pt1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 4. Eight hole paper tape.</i></span></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #741b47;">[Eight hole paper tape was 1" (25.4mm) wide and had rows of holes punched through it at ten rows per inch. As well as the 8 data holes there was a smaller sprocket hole. The sprocket hole was punched on every row and in early times engaged with a tooth of a wheel that fed the paper tape through a reading device. Latterly with optical readers they were used to sense a row. The other eight possible positions were punched with a combination to represent characters of the alphabet, numbers, and special characters.]</span></i><br />
<br />
<br />
<b><span style="color: #0c343d;">III. Output
</span></b><br />
<br />
"The current value of any number or letter variables must be
recorded in Flexo code on magnetic tape for later printing
by inserting the word PRINT followed by the desired letters,
followed by a period. The first and last characters recorded
by each PRINT instruction are carriage returns."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJsHmsdMgcQgNG92ZdRyLkqlUuNGMfzUkyjoiAVGbJwPRFWNvgpnBhmAMcddLUYsl-p0PDfnHxZgVHseYlDBWKFt1JlDBx2scA8RO-Lu3tkwgXeRP4HMsSOLxOCF_8ulKKJe8sL2zzNfyq/s1600/1951_TapeData_P4.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="400" data-original-width="400" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJsHmsdMgcQgNG92ZdRyLkqlUuNGMfzUkyjoiAVGbJwPRFWNvgpnBhmAMcddLUYsl-p0PDfnHxZgVHseYlDBWKFt1JlDBx2scA8RO-Lu3tkwgXeRP4HMsSOLxOCF_8ulKKJe8sL2zzNfyq/s320/1951_TapeData_P4.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 5. IBM 726 magnetic tape storage unit announced May 1952.</i></span></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">IV. Jump Instructions
</span></b><br />
<br />
"Equations are ordinarily carried out in the sequence in
which they are written. This sequence may be interrupted by
inserting one of four jump instructions. The address section
of a jump instruction must be an integer less than 100. This
integer is the number of the equation to which the jump is
to be made. An equation is numbered by preceding it by its
number, e.g., 15 x=3a assigns the number 15 to the equation
x = 3a.
<br />
<br />
The instruction SP 15, inserted in a routine will cause
equation 15 to be executed next, the normal sequence
continuing from that new point.
<br />
<br />
The instruction SR 15, causes equation 15 to be executed
next but the control returns to the equation following the
SR 15. SR evidently implies that a closed subroutine is to
be executed.
<br />
<br />
The instructions CP and CR are obeyed only if the quantity
most recently computed was negative; otherwise they are
ignored."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJfAfUuXSldvZDMmiln77-FEzP3oJfFMt-UVss_kG5MKLCxZb-yHIPxEtOri18ZkbvKZZuv-djHLpXdpqEvwxR7-rv6Uy7bT7aTCWHduf4F6l_YbKjxPuVTSgME2lyGzRBCtj-djQQ1hPk/s1600/Whirlwind_I.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="463" data-original-width="976" height="188" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJfAfUuXSldvZDMmiln77-FEzP3oJfFMt-UVss_kG5MKLCxZb-yHIPxEtOri18ZkbvKZZuv-djHLpXdpqEvwxR7-rv6Uy7bT7aTCWHduf4F6l_YbKjxPuVTSgME2lyGzRBCtj-djQQ1hPk/s400/Whirlwind_I.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Figure 6. Whirlwind I occupied 2,500 square feet on the second floor.</i></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">V. Function Subroutines
</span></b><br />
<br />
"23 Function subroutines are now available in the
Laning-Zierler system. Each is assigned a number (1- 23) and
is called for by writing the proper number as the exponent
of an upper case F. For example:
<br />
<br />
<br />
<pre><span style="font-size: large;"> X=2(F^1(y)F^2(z)+F^11(z)),</span>
</pre>
<br />
<br />
sets<br />
<br />
<b> x = 2(sqrt(y) sin(z) + |z|),</b><br />
<br />
since Subroutine 1 is the
square root, 2 is the sine, and number 11 is a subroutine
which produces the magnitude of the indicated argument.
Other subroutines include inverse trigonometric functions,
exponential and hyperbolic functions, logs to the base 10,
2, and e, etc."<br />
<br />
<b><span style="color: #0c343d;"><br /></span></b>
<b><span style="color: #0c343d;">VI. Additional variable and variable </span></b><span style="color: #0c343d;"><b>indices</b></span><br />
<br />
"Subscripts are not avai1able on the MIT Flexowriters.
Numerical subscripts are obtained by typing x|3 for x
subscript 3, etc. Variable subscripts are obtained by using
letters after the vertical bar, e.g., x|n is typed for x
subscript n, and if n happens to equal 3, x|n is equivalent
to x|3."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcevaLvv6EuQkqHq9edMd0XzNLKgP5B5NC5y4tFq6LIjDy9-eVravHVZg-V6i8f16tRMMhurjKpMn5tdUYa-wPY-KiK3oObjUWRLSzprSDRdICVeyCC6ECd0FW4G96K6IrKn-Wio50U2DN/s1600/Whirlwind_thf5003.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="1165" data-original-width="1500" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhcevaLvv6EuQkqHq9edMd0XzNLKgP5B5NC5y4tFq6LIjDy9-eVravHVZg-V6i8f16tRMMhurjKpMn5tdUYa-wPY-KiK3oObjUWRLSzprSDRdICVeyCC6ECd0FW4G96K6IrKn-Wio50U2DN/s400/Whirlwind_thf5003.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 7. 1952 - Forrester (far left, standing) and Norman Taylor (far left, pointing) inspect completed circuitry.</i></span></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">VII. Auxiliary Storage
</span></b><br />
<br />
"There is room in the Whirlwind high-speed storage for about
250 variables.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmkIZ-ObNpJKEwy8LwwEFcW-4DubmWDdtq5APn8wAW2h0LYl4TbQGUUDW9meaSNapPxA29vlHLzZyumuhDp7Ei712kNZgbTCfAr1mWNSSjhhNmsoH6ZIouBALkMRPLd1Ic2orPCdcK9e5W/s1600/mag-core-close-up.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="341" data-original-width="432" height="315" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmkIZ-ObNpJKEwy8LwwEFcW-4DubmWDdtq5APn8wAW2h0LYl4TbQGUUDW9meaSNapPxA29vlHLzZyumuhDp7Ei712kNZgbTCfAr1mWNSSjhhNmsoH6ZIouBALkMRPLd1Ic2orPCdcK9e5W/s400/mag-core-close-up.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: small; text-align: start;"><i><span style="color: #cc0000;">Figure 8. Close-up of magnetic core memory showing 64 x 64 arrangement of magnetic elements on surface plane. circa 1954.</span></i></span></td></tr>
</tbody></table>
<br />
Additional values, such as tables, must be assigned to the Whirlwind auxiliary magnetic drum.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVxgIE0S0TBfjm4C-Zs8qLuk3ZxVdHi-mwK8AQ6mKqDM5Pd71euNXcfJpuuHuWg6I4wMBcZlDmq85E_CzeQICUCyLuE1CYOv2SEwLpJqbmmNIXOL07PpK1MmXqXgbsAoOVtA-pvImLgzOb/s1600/1932_Drum_P3.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="322" data-original-width="400" height="321" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiVxgIE0S0TBfjm4C-Zs8qLuk3ZxVdHi-mwK8AQ6mKqDM5Pd71euNXcfJpuuHuWg6I4wMBcZlDmq85E_CzeQICUCyLuE1CYOv2SEwLpJqbmmNIXOL07PpK1MmXqXgbsAoOVtA-pvImLgzOb/s400/1932_Drum_P3.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 9. ERA employees with magnetic drum memory units 1955.</i></span></span></td></tr>
</tbody></table>
<br />
The word ASSIGN is used for this purpose. For example, the instruction,
<br />
<br />
<br />
<pre><span style="font-size: large;"> ASSIGN a|4</span>
</pre>
<br />
<br />
automatically reserves space on the drum for variables a|1
through a|4. If these variables have the values 2, 4, 6, 8,
respectively, they may be assigned these values and have
space reserved for them on the drum by writing only
<br />
<br />
<br />
<pre><span style="font-size: large;"> a|N=2,4,6,8
</span></pre>
<br />
<br />
Further, the same thing can be accomplished by writing
<br />
<br />
<br />
<pre><span style="font-size: large;"> a|N=2(2)8,</span>
</pre>
<br />
<br />
A more complicated example might be"<br />
<br />
<br />
<pre><span style="font-size: large;"> a|N=1(.5)2(.25)2.5(1)4.5,</span>
</pre>
<br />
<br />
<b><span style="color: #0c343d;">VIII. Differential Equations
</span></b><br />
<br />
"Provision has been made for the automatic solution of
ordinary differential equations using Gills' variation of
the 4th order <a href="https://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods" target="_blank">Runge-Kutta Method</a>.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJX86u2OXnOXLfdIkIskHcKujtQ8POxvEiS0edUjSJshaH6mkATibmcJWClpnfVNitE0LYG91FIRoUV3XPiGWO79K6fFFyJYakdNSB2q1so1yZ7YrcRH5vomJ19U9HKv_F_lngoHotaePg/s1600/runge.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="397" data-original-width="495" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJX86u2OXnOXLfdIkIskHcKujtQ8POxvEiS0edUjSJshaH6mkATibmcJWClpnfVNitE0LYG91FIRoUV3XPiGWO79K6fFFyJYakdNSB2q1so1yZ7YrcRH5vomJ19U9HKv_F_lngoHotaePg/s400/runge.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="text-align: start;"><span style="color: #cc0000; font-size: small;"><i>Figure 10. First find values at a half step forward (in time). This technique is known as the second-order Runge-Kutta method.</i></span></span></td></tr>
</tbody></table>
<br />
For this purpose<br />
<br />
<ol>
<li>the letter t must be used for the independent
variable,</li>
<li>h must be used for the increment in t,</li>
<li>D must be used to denote d/dt,</li>
<li>Any other variables and/or superscript variables
may be used for the dependent and auxiliary
variables.</li>
</ol>
<br />
Suppose we have the two equations<br />
<br />
<b> f'1(t, y1, y2) = y2 + 1
<br /> f'2(t, y1, y2) = -y1
</b><br />
let<br />
<br />
<b> t = 2(0.5)10,</b><br />
<br />
that is,<br />
<br />
<b> h = 0.5.
</b><br />
<br />
Our program might be:
<br />
<br />
<pre><span style="font-size: large;"> t=2,
h=O.5,
y|1=0,
y|2=0,
1 Dy|1=y|2+1,
Dy|2=-y|l,
k=t-10.1,
CP 1
STOP</span>
</pre>
<br />
t is automatically increased by h upon completion of the
last equation that starts with D. One important restriction
is that all relevant auxiliary computation must be done
between the first and last D equations."<br />
<br />
<br />
<b><span style="color: #0c343d;">IX. Postmortems
</span></b><br />
<br />
<i><span style="color: #741b47;">[Post-mortems - Method and arrangements for generating debugging information following software failure.]
</span></i><br />
<br />
"Automatic postmortem features are still in the design
stage. Features now available include:
<br />
<br />
<br />
<ol>
<li>If the program is too long the computer stops and types
out information indicating where and how storage was
exceeded.</li>
<li>If an alarm occurs the computer prints out the number of
the equation in which the alarm occurred and the number of
the equation which preceded the alarm. (Equations not
assigned numbers by the programmer are automatically
assigned numbers from 101 to 200.)</li>
<li>The programmer may obtain the values of any variables he
desires after an alarm by writing the appropriate PRINT
instruction as equation 100."</li>
</ol>
<br />
<br />
<b><span style="color: #0c343d;">X. Conclusion
</span></b><br />
<br />
"The system described is a working system and has been used
by the Instrumentation Laboratory to solve several complex
problems. One problem involved a set of six simultaneous
differential equations. The equations involved extremely
complicated algebraic and trigonometric calculations. Coding
required only a few hours and the routine ran successfully
the first time. Computing time was about six to eight times
as long as it would have been using the single-address
interpretive system ordinarily used at the Digital Computer
Laboratory.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-lbEa8Wos2rlMgb3nGkZcieb-yHAkO1g51-EVr3moRwfVnbELt1g-WlaDgvx8aNyEqwCngGa0iMTI4QKZh3N-WWnOp0qm5_VQsm1wyHlqBeSHv8-l2SnPIUwCOMXIvC_YXuynxuyjNXna/s1600/BILD11.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="380" data-original-width="299" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-lbEa8Wos2rlMgb3nGkZcieb-yHAkO1g51-EVr3moRwfVnbELt1g-WlaDgvx8aNyEqwCngGa0iMTI4QKZh3N-WWnOp0qm5_VQsm1wyHlqBeSHv8-l2SnPIUwCOMXIvC_YXuynxuyjNXna/s400/BILD11.JPG" width="313" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 11. George program listing.</i></span></td></tr>
</tbody></table>
<br />
Much work remains to be done on the system particularly with
respect to increasing the computing speed and improving
postmortem facilities. Heretofore there has been very
little need for elaborate post-mortem facilities, because,
with a single exception, all programs coded in the
Laning-Zierler system have been completed successfully on
their first run."<br />
<br />
<br />
<b><span style="color: #0c343d;">VIDEOS</span></b><br />
<br />
YouTube Video - <a href="https://youtu.be/5ZQP4G3Qwb4" target="_blank">"See It Now: Jay W. Forrester and the WHIRLWIND Computer - (1951)"</a><br />
<br />
<br />
<b>RESOURCES</b>
<br />
<br />
/1/ Combelic, Algebraic Coding - Massachusetts Institute of
Technology Summer Session 1954 - DIGITAL COMPUTERS, ADVANCED
CODING TECHNIQUES - archive.org
<br />
<br />
/2/ Link to "George User Manual" -
<a href="https://archive.org/details/bitsavers_mitwhirlwiamForTranslationofMathematicalEquationsF_1080308" target="_blank">https://archive.org/details/bitsavers_mitwhirlwiamForTranslationofMathematicalEquationsF_1080308</a><br />
<br />
<div style="text-align: center;">
* * *
</div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-37720859797428885192017-02-12T01:49:00.006+00:002017-02-12T17:12:34.176+00:00LM Descent to the Moon - Part 7 - Crew Comments (1969)(Apollo 11 LM - DOI to Touchdown Crew Debriefing, 1969)
<br />
<br />
<i><span style="color: #274e13;">[The following is a partial reprint of NASA's Apollo 11
crew interviews /1/ during their quarantine that took
three weeks after their splash down. Apollo 11 CM splashed down on July 24, 1969.]
</span></i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBzaO7xgtVDNecW9NFyMs8uc6KUTFm-c8fDVkElINZTgMjM69wQ_fj4Vks2gOr4Ob8T7s8PsCsK2oBmnguxjKQZVinjDitXHKhrKRS2l8cVndsjWBs9CfsBPq6MpTcOwhllJnXyKeBzxbf/s1600/s69-31739.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="313" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBzaO7xgtVDNecW9NFyMs8uc6KUTFm-c8fDVkElINZTgMjM69wQ_fj4Vks2gOr4Ob8T7s8PsCsK2oBmnguxjKQZVinjDitXHKhrKRS2l8cVndsjWBs9CfsBPq6MpTcOwhllJnXyKeBzxbf/s400/s69-31739.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 1. ARMSTRONG, COLLINS and ALDRIN.<br />The Apollo 11 mission, launched on July 16, 1969 and returned to Earth on July 24, 1969. Aboard the space craft were astronauts Neil A. Armstrong, commander; Michael Collins, Command Module (CM) pilot; and Edwin E. Aldrin Jr., Lunar Module (LM) pilot</i></span></td></tr>
</tbody></table>
<br />
<a name='more'></a><b><span style="color: #0c343d;">1. Preparation for DOI [Descent Orbit Insertion]</span></b><br />
<br />
"<u style="font-style: italic; font-weight: bold;">ALDRIN</u> - It was 40 minutes before DOI that we were scheduled
to begin the P52 and we were about 2
minutes behind when we completed looking at the radar and
VHF ranging and designated the radar down so that we
could do the P52.
<br />
<i><span style="color: #274e13;"><br /></span></i>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBhEJBAdqtxBPmxNjdBJ1VTR_Q4CwDNBhQJ2oAdNo2SBvBuUIVu1J_0-qZnoHPY3KP81CX7Rp4d9e-7gDI9nzSR2wxeq88R-gc91VlFry_XY-3roGi_KXvaCyhiCWpGl1HhJe_LtA3EfNo/s1600/P02_F09_625.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBhEJBAdqtxBPmxNjdBJ1VTR_Q4CwDNBhQJ2oAdNo2SBvBuUIVu1J_0-qZnoHPY3KP81CX7Rp4d9e-7gDI9nzSR2wxeq88R-gc91VlFry_XY-3roGi_KXvaCyhiCWpGl1HhJe_LtA3EfNo/s400/P02_F09_625.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 2. IMU-5 for Apollo GetN Equipment opened. Apollo inner, middle and outer IMU gimbal assemblies visible.</i></span></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBfbpe-FItTkfNZQgvZW-XKp8dTKm78Nx6M8F-GZ0dBSZ-czt496JAFf9cQ6trQhkViKE7PiMsVKd4xQ4VSwtm2WtRIpKOxhWovzgdrV6ILofNCtKQ0uiNO-v-VO7G65T9lx1zdawNqXjW/s1600/P02_F10_625.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="353" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBfbpe-FItTkfNZQgvZW-XKp8dTKm78Nx6M8F-GZ0dBSZ-czt496JAFf9cQ6trQhkViKE7PiMsVKd4xQ4VSwtm2WtRIpKOxhWovzgdrV6ILofNCtKQ0uiNO-v-VO7G65T9lx1zdawNqXjW/s400/P02_F10_625.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 3. Apollo IMU, Naviation base and optical subsystem.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">[<u>P52 - IMU alignment program 52</u></span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Aligns the IMU to one of three orientations selected by the astronaut. The present IMU orientation is known and is stored in REFSMMAT.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The three possible orientations may be:</span></i><br />
<br />
<ol>
<li><i><span style="color: #274e13;">Preferred orientation: An optimum orientation for a previously calculated maneuver. this orientation must be calculated and stored by a previously selected program.</span></i></li>
<li><i><span style="color: #274e13;">Nominal orientation</span></i></li>
<li><i><span style="color: #274e13;">RERSMMAT orientation</span></i></li>
</ol>
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">After a IMU orientation has been selected routine S52.2 is operated to compute the gimbal angles using the new orientation and the present vehicle attitude. CAL52A then uses these angles, stored in THETAD, +1, +2, to coarse align the IMU. The stars selection routine, R56, is then operated. If 2 stars are not available an alarm is flashed to notify the astronaut.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">At this point the astronaut will maneuver the vehicle and select 2 stars either manually or automatically. After 2 stars have been selected the IMU is fine aligned using routine R51. If the rendezvous navigation process is operating (indicated by RNDVZFLG) P20 [</span></i><i><span style="color: #274e13;">Rendezvous navigation program 20</span></i><i><span style="color: #274e13;">] is displayed. Otherwise P00 [IDLE] is requested.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The program is called by the astronaut by DSKY entry.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Output -- the following may be flashed on the DSKY</span></i><br />
<br />
<ol>
<li><i><span style="color: #274e13;">IMU orientation code</span></i></li>
<li><i><span style="color: #274e13;">Alarm code 215 - preferred IMU orientation not specified</span></i></li>
<li><i><span style="color: #274e13;">Time of next ignition</span></i></li>
<li><i><span style="color: #274e13;">Gimbal angles</span></i></li>
<li><i><span style="color: #274e13;">Alarm code 405 - two stars not available</span></i></li>
<li><i><span style="color: #274e13;">please perform p00</span></i></li>
</ol>
<br />
<i><span style="color: #274e13;">The mode display may be changed to 20]</span></i><br />
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - I don't think we had any difficulties with the
DOI prep.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhV6QQMiA-SM-EdMQHhPPdO9oY45FrUmOMoUt3WMj1fImxv_pXo9iAp7n3XBgunq6n7XETLwVNnYiE2lYMGNrOJODfpiJBXLX8dt4jTpJETkvx1umOwG8FH49WZg6CDFoCYy6T5VxeCzAHS/s1600/MSFC-6901225.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="341" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhV6QQMiA-SM-EdMQHhPPdO9oY45FrUmOMoUt3WMj1fImxv_pXo9iAp7n3XBgunq6n7XETLwVNnYiE2lYMGNrOJODfpiJBXLX8dt4jTpJETkvx1umOwG8FH49WZg6CDFoCYy6T5VxeCzAHS/s400/MSFC-6901225.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 4. 1969-07-24, Apollo 11 Crew Boards U.S.S. Hornet Aircraft Carrier. Shown here are the three astronauts (L-R) Aldrin, Armstrong, and Collins leaving the recovery helicopter aboard the U.S.S. Hornet after their splashdown in the Pacific Ocean. Wearing biological isolation garments donned before leaving the spacecraft, the three went directly into the Mobile Quarantine Facility (MQF) on the aircraft carrier. The MQF served as their home for 21 days following the mission.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">2. DPS/DOI burn
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - At DOI ignition, which was our first DPS
<i><span style="color: #274e13;">[Descent Propulsion System]</span></i> maneuver, I could not hear the
engine ignite. I could not feel it ignite, and the only way
that I was sure that it had ignited was by looking at
chamber pressure and accelerometer. Very low acceleration -
-
<br />
<br />
<b><i><u>COLLINS</u></i></b> - I would think under zero g, it would throw you
against your straps, one way or the other.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs4hEIkwTJvSIJGrnxWWHr5c_pPMWAFECbji_-EjzCFNGWmJBwXoVT_9ZinoYBkrOYpe3OUjMJIR4Hs1zKJPdx6-t8TchOtGdhctjjz3gvMGP-1xXrNOAkZw7LJj3D5FL30aEw5FoyChG_/s1600/Restraint.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="356" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs4hEIkwTJvSIJGrnxWWHr5c_pPMWAFECbji_-EjzCFNGWmJBwXoVT_9ZinoYBkrOYpe3OUjMJIR4Hs1zKJPdx6-t8TchOtGdhctjjz3gvMGP-1xXrNOAkZw7LJj3D5FL30aEw5FoyChG_/s400/Restraint.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 5. Lunar Module straps to hold astronauts in desired position under zero gravity.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ARMSTRONG</u></i></b> - We're pulled down into the floor with the
restraint, and the difference between that and the
10-percent throttle acceleration was not detectable to me,
However, at 15 seconds, when we went to 4O percent, it
definitely was detectable.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - On the restraints, I found that instead of being
pulled straight down, the general tendency was to be pulled
forward and outboard. So much so that this might have been a
suit problem, as my right foot around the instep was taking
a good bit of this load, being pulled down to the floor.<br />
<br />
It
did feel as though the suit was a little tight. Prior to
power descent <i><span style="color: #274e13;">[powered descent phase, when the DPS engine
runs all the way to the surface]</span></i>, the problem was obscured
from my mind, but it was aggravated somewhat by the
restraint pulling down and forward.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinpO6pocgJtt5FQ64LpFGSp5Si0mZu-_zZmZYIpjw80J6sbkrykCVwF2ObpoEFjI6l7tBMKIIzSuTY1-CujTozcdk0bm_MLdfkvip6TXJYPiC2ONmElQ3B5GDWTsXyxaL1OiZlt-KOuAXU/s1600/01.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinpO6pocgJtt5FQ64LpFGSp5Si0mZu-_zZmZYIpjw80J6sbkrykCVwF2ObpoEFjI6l7tBMKIIzSuTY1-CujTozcdk0bm_MLdfkvip6TXJYPiC2ONmElQ3B5GDWTsXyxaL1OiZlt-KOuAXU/s400/01.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 6. Lunar Module astronaut flight stations.</i></span></td></tr>
</tbody></table>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<b><i><u>ARMSTRONG</u></i></b> - I guess I noticed that last - I had expected a
good bit of lateral shifting due to reports of previous
flights.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - I was able to lean over and make entries on the
data card without pulling it down; but as you can see, when
you do make entries on them, you make them sideways.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5UqxkxM8NPyTjoY942b6cVu-5G_ynN21l_a008Czdg3vwUKJgFqP5Jk0iuJrhrEmRpD7diEyDhd1TTzzN9-NC5Hh8qfnc9kY7yd9wrMSmPct1nxLj8Z52gJusctlxeMbr9vG8K0CC4N9W/s1600/02.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto; text-align: center;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5UqxkxM8NPyTjoY942b6cVu-5G_ynN21l_a008Czdg3vwUKJgFqP5Jk0iuJrhrEmRpD7diEyDhd1TTzzN9-NC5Hh8qfnc9kY7yd9wrMSmPct1nxLj8Z52gJusctlxeMbr9vG8K0CC4N9W/s400/02.PNG" width="260" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 7. Atronaut flight station.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The cut-off was a guided cut-off. What about the
residuals?
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - We burned both X and Z, and I'm sure they weren't
in excess of .4.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - It was less than 1 ft/sec, but I don't recall
the tenths.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfaORMTYy4ZC34n5dT_7tjcj6CQXVXK-OKpbrkRZQsXxjaZKdXvjEdcRpJz6qJzlkU4-J38KHHstXyrFlrXOa9FZsXWR6pLaRsJhm2Ut6rHP9ztEeakZLJReVm4wkxIs5PXE64U3Nr5I4t/s1600/s69-40205.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="261" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfaORMTYy4ZC34n5dT_7tjcj6CQXVXK-OKpbrkRZQsXxjaZKdXvjEdcRpJz6qJzlkU4-J38KHHstXyrFlrXOa9FZsXWR6pLaRsJhm2Ut6rHP9ztEeakZLJReVm4wkxIs5PXE64U3Nr5I4t/s400/s69-40205.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 8. S69-40205 (27 July 1969) -- The crewmen of the Apollo 11 lunar landing mission go through their post flight debriefing session on Sunday, July 27, 1969. Left to right, are astronauts Edwin E. Aldrin Jr., lunar module pilot; Michael Collins, command module pilot; and Neil A. Armstrong, commander. They are seated in the debriefing room of the Crew Reception Area of the Lunar Receiving Laboratory at the Manned Spacecraft Center.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">6. Trimming residuals
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - It's probably worth noting that the flight plan
at this point does not adequately reflect the time
requirements of the flight. I think the DOI rule in the
flight plan says, "Trim Vx residuals."
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - So does your checklist.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp4Tcs28hL4olQfBAVP5_VwH0I33Cg6srDl0glrH4iW_UrEBoHF1HEbdWA8xS5FhP8WZYjWGCTYKULipkSMiJwbwyHzNJyR4JAI1oRJy2nwRT0z0lalZTU8tWhV9jybDABQC4zELs92qKr/s1600/Display2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp4Tcs28hL4olQfBAVP5_VwH0I33Cg6srDl0glrH4iW_UrEBoHF1HEbdWA8xS5FhP8WZYjWGCTYKULipkSMiJwbwyHzNJyR4JAI1oRJy2nwRT0z0lalZTU8tWhV9jybDABQC4zELs92qKr/s400/Display2.png" width="253" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 9. Typical DSKY 3COMP display. R1, R2 and R3 shown. VERB 6 NOUN 36 (DISPLAY DECIMAL IN R1, R2 AND R3 / TIME OF AGC CLOCK 00xxx HOUR, 000xx MIN, 0xx.xx SEC), program or phase is P00.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ARMSTRONG</u></i></b> - That isn't right. This was a result of that
orbital change that was put in late, and paperwork and so on
just couldn't keep up with those last-minute changes. But,
again, it shows that last-minute changes are always
dangerous. You could follow the flight plan here and
possibly foul up the procedure. Do you recall the VERB 82
<i><span style="color: #274e13;">[REQUEST ORBIT PARAM DISPLAY (R30)]</span></i> values? 9.5 was
perilune, I think.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4Y_4S_8-rW4cPjijWsOtGwUssiXeIhZBz_tBkzpHNDC3vm0v8TRQJpeYSvrsxhh6h-3j8AHsJFnVf1jTJfbXJD9IEGhCBOVl9oHE_kZaWZjjPwUKx1hgHlqyiWkK6mYAuJLjgJKrqpvzd/s1600/verb-and-noun-buttons-apollo-moon-guidance-computer-S057X9.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="333" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4Y_4S_8-rW4cPjijWsOtGwUssiXeIhZBz_tBkzpHNDC3vm0v8TRQJpeYSvrsxhh6h-3j8AHsJFnVf1jTJfbXJD9IEGhCBOVl9oHE_kZaWZjjPwUKx1hgHlqyiWkK6mYAuJLjgJKrqpvzd/s400/verb-and-noun-buttons-apollo-moon-guidance-computer-S057X9.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 10. VERB and NOUN buttons have a long history in MIT guidance and navigation keyboards.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ALDRIN</u></i></b> - Preburn for NOUN 42 was 57.2 and 8.5. We had 57.2
and 9.1 after the maneuver.
<br />
<br />
<i><span style="color: #274e13;">[N42, </span></i><i><span style="color: #274e13;">3COMP, DEC ONLY,</span></i><br />
<i><span style="color: #274e13;"> APOGEE, xxxx.x NAUT MI</span></i><br />
<i><span style="color: #274e13;"> PERIGEE, xxxx.x NAUT MI</span></i><br />
<i><span style="color: #274e13;"> DELTA V (REQUIRED) xxxx.x FT/SEC]
</span></i><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - I guess we can't account for that.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIy_hOh5q4LtUExhk4-mNapWQ5OyT8RzPCkwqYWEI4FnQ_ui9sWcC7oolNLo7DZdVz4yrrOFTrb9s6q0gyNxmI_O7sklS9371YLz3zZCkVvyejI_WQzXA_Au6OZKNn987BmKSPxkY1cT9L/s1600/Fig_4_Coordinates.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="380" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIy_hOh5q4LtUExhk4-mNapWQ5OyT8RzPCkwqYWEI4FnQ_ui9sWcC7oolNLo7DZdVz4yrrOFTrb9s6q0gyNxmI_O7sklS9371YLz3zZCkVvyejI_WQzXA_Au6OZKNn987BmKSPxkY1cT9L/s400/Fig_4_Coordinates.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 11. Lunar-descent coordinates. G stands guidance.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ALDRIN</u></i></b> - No. The NOUN 86 <i><span style="color: #274e13;">[N86 - VG (LV) 3COMP xxxx.x FT/SEC
FOR EACH, DEC ONLY]</span></i> <i><span style="color: #274e13;">[LV - Local Vertical]</span></i> that we got out of the thrust program
also differed from what the ground gave us in the pad,
primarily, in the Z-component that's loaded into the AGS
<i><span style="color: #274e13;">[Abort Guidance System]</span></i>; that pad value is 9.0, and the
computer came up with 9.5.<br />
<br />
The coordinate frame that you
load them in is frozen inertially, and if there are any
discrepancies in the freezing of this, you will get a
slightly different burn direction required out of the two
guidance systems. I think that explains the larger AGS
residual in the Z-direction of minus 0.7. I think we would
have to have the guidance people verify that the difference
in NOUN 86 produced that error in that direction.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgikHo3mI3XArqeQhZcpbiSZfpRkoZNhyphenhyphenjp1b9nzDt3CyJIeECfmYW3A2DHJuUkSAa_ojb6JS78-bCUb3Ga8exy3XyyeNAy4HjZ1QFLlpq9_JViJ2iGaMKzFizqhAcaDVd7B8sWkgpTV404/s1600/s69-40209.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgikHo3mI3XArqeQhZcpbiSZfpRkoZNhyphenhyphenjp1b9nzDt3CyJIeECfmYW3A2DHJuUkSAa_ojb6JS78-bCUb3Ga8exy3XyyeNAy4HjZ1QFLlpq9_JViJ2iGaMKzFizqhAcaDVd7B8sWkgpTV404/s400/s69-40209.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 12. S69-40209 (27 July 1969) -- The crewmen of the Apollo 11 lunar landing mission go through their post flight debriefing session on Sunday, July 27, 1969. Left to right, are astronauts Edwin E. Aldrin Jr., lunar module pilot; Michael Collins, command module pilot; and Neil A. Armstrong, commander. They are seated in the debriefing room of the Crew Reception Area of the Lunar Receiving Laboratory at the Manned Spacecraft Center (MSC). In the foreground are Donald K. Slayton (right), MSC Director of Flight Crew Operations; and Lloyd Reeder, training coordinator.</i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<b><span style="color: #0c343d;">9. Radar tracking
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - We had a good manual radar acquisition, and data
from the radar agreed well with the VHF ranging information.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - Again, we had P20 in the background, but we didn't
use it. This was a manual lockon.
<br />
<br />
<i><span style="color: #274e13;">[P20 - Rendezvous navigation program 20,
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The purpose of this program is to control the rendezvous
radar from startup through acquisition and lockon to the CSM
[Command and Service Module] and to update either the LM
[Lunar Module] or CSM state vector (as specified by the
astronaut by DSKY [Lunar Module computer display and
keyboard] entry) on the basis of the RR tracking data.
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Calling sequence</span></i><br />
<i><span style="color: #274e13;"> - astronaut request through DSKY V37E20E</span></i><br />
<i><span style="color: #274e13;"> V37 - CHANGE PROGRAM (MAJOR MODE)</span></i><br />
<div>
<span style="color: #274e13;"><i> P20 - </i></span><i><span style="color: #274e13;">Rendezvous navigation program 20</span></i><span style="color: #274e13;"><i><br /></i></span><i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">P20 may be terminated in two ways</span></i><br />
<i><span style="color: #274e13;"> - astronaut selection of idling program (P00)</span></i><br />
<i><span style="color: #274e13;"> by
keying V37E00E or</span></i><br />
<i><span style="color: #274e13;"> - by keying in V56E
</span></i><br />
<i><span style="color: #274e13;"><span style="color: #274e13;"> V</span>56 - TERMINATE TRACKING (P20 + P25)</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Alarm or abort exit modes
- range greater than 400 NM
</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Display output</span></i><br />
<i><span style="color: #274e13;"> - TRKMKCNT = no of rendezvous tracking marks taken
(counter)]
</span></i><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The radar was depowered to cool during the DOI
to PDI <i><span style="color: #274e13;">[Powered Descent Initiation]</span></i> phase.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhluzxsGCwjcfriDjtgS6aqG_CXFUfpalt48hEkZxvYjHms1CQh0BLcRIeoU_j00a8GgPzvu3OFIcstue5vJAetkLOF7qTHP5KvoyFDN1VBfKdemKxX9XJNIQXFG6lyOEFmFtJUEyDA1buJ/s1600/s69-40307.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="307" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhluzxsGCwjcfriDjtgS6aqG_CXFUfpalt48hEkZxvYjHms1CQh0BLcRIeoU_j00a8GgPzvu3OFIcstue5vJAetkLOF7qTHP5KvoyFDN1VBfKdemKxX9XJNIQXFG6lyOEFmFtJUEyDA1buJ/s400/s69-40307.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 13. S69-40307 (30 July 1969) -- The crewmen of the historic Apollo 11 lunar landing mission stand in the serving line as they prepare to dine in the Crew Reception Area of the Lunar Receiving Laboratory, Building 37, Manned Spacecraft Center. Left to right, are astronauts Edwin E. Aldrin Jr., Michael Collins, and Neil A. Armstrong. They are continuing their postflight debriefings. The three astronauts will be released from quarantine on Aug. 11, 1969.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">16. Adequacy of procedures necessary to accomplish DPS
maneuver
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The <i><span style="color: #274e13;">[inertial]</span></i> platform drift check, a P52, was done
against the Sun. This procedure seemed to work as we had
planned; however, the variation in the data was somewhat
larger that I would've guessed. Do you have those numbers?
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - Yes. The technique that we used was to compare what
the computer thought the little gimbal or the inner angle
was and to point the rear detent at the Sun. We'd compare
that with what the actual middle gimbal was. Now we did this
in PGNS <i><span style="color: #274e13;">[Primary Guidance and Navigation System]</span></i> pulse.<br />
<br />
The way that we found to work out best was for Neil to me
when, in the background, we'd have the AUTO maneuver display
50 18<br />
<br />
<i><span style="color: #274e13;">[V50</span></i><br />
<i><span style="color: #274e13;"> PLEASE PERFORM</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">N18,</span></i><i><span style="color: #274e13;"> 3COMP,</span></i><br />
<i><span style="color: #274e13;"> AUTO MANEUVER BALL
ANGLES,</span></i><br />
<i><span style="color: #274e13;"> xxx.xx DEG</span></i><br />
<i><span style="color: #274e13;"> xxx.xx DEG</span></i><br />
<i><span style="color: #274e13;"> xxx.xx DEG </span></i><i><span style="color: #274e13;">]</span></i><br />
<br />
in P52. We'd call up on
top of that VERB 6 NOUN 20 or 22<br />
<br />
<i><span style="color: #274e13;">[V6</span></i><br />
<i><span style="color: #274e13;"> DISPLAY DECIMAL IN R1
OR R1,R2 OR R1,R2,R3</span></i><br />
<i><span style="color: #274e13;">N20, </span></i><i><span style="color: #274e13;">3COMP,</span></i><br />
<i><span style="color: #274e13;"> ICDU ANGLES,</span></i><br />
<i><span style="color: #274e13;"> xxx.xx DEG</span></i><br />
<div>
<i><span style="color: #274e13;"> xxx.xx DEG</span></i></div>
<div>
<i><span style="color: #274e13;"> xxx.xx DEG</span></i></div>
<div>
<i><span style="color: #274e13;"><br /></span></i></div>
<i><span style="color: #274e13;">N22, 3COMP,</span></i><br />
<i><span style="color: #274e13;"> NEW ICDU ANGLES,</span></i><br />
<i><span style="color: #274e13;"> xxx.xx DEG</span></i><br />
<div>
<i><span style="color: #274e13;"> xxx.xx DEG</span></i></div>
<div>
<i><span style="color: #274e13;"> xxx.xx DEG ]</span></i></div>
<div>
<i><span style="color: #274e13;"><br /></span></i></div>
<i><span style="color: #274e13;">[ICDU - Inertial system Coupling Data Unit].</span></i><br />
<br />
And I'd have
NOUN 20 up. As soon as Neil would say "MARK", I'd hit ENTER
<i><span style="color: #274e13;">[DSKY button, enter the command]</span></i>, record NOUN 20. Now the
desire is to find out exactly what the computed value is in
a close time period. So what I would do is hit the ENTER on
the NOUN 20, visually recall what those numbers were, not
write them down, but hit KEY RELEASE <i><span style="color: #274e13;">[DSKY button, it was
used to release the control of the DSKY to other routines]</span></i>,
which put me back to the 50 18 display. A PROCEED <i><span style="color: #274e13;">[DSKY
button, confirms AGC so the program can continue]</span></i> would
recompute the numbers or maneuver. As soon as I would do
that, those numbers would be frozen and the desired gimbal
angles would be loaded in NOUN 22.<br />
<br />
Then it was just a
question of my calling them up, and they should not change
the time I hit ENTER to record the gimbal angle that we had
until it was recomputed as a desired one that did not exceed
3 seconds. Of course, we had pretty low rates. So I think
that the comparison didn't suffer any from a lack of proper
procedure. We did find that the numbers were a little larger
than we thought they would be. We had it worked out with the
ground how we arranged the signs on the differences, so we'd
subtract NOUN 22 <i><span style="color: #274e13;">[NEW ICDU ANGLES]</span></i> from NOUN 20 <i><span style="color: #274e13;">[ICDU
ANGLES]</span></i>. The first one was 0.19; second one, 0.16; and the
third one, 0.11. The GO/NO-GO value was 0.25. So we're a
little closer to this than we had hoped to be.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhONLxExgY4Uthb3b6SJqrNlx_uiI3dGnDSH6vBM9QeYTPqwXnVaXsHXKEkXGfec9BIlO74_k6bXFJ-Wq0k61tZxGNgFU-L9G4yBJq2Bi4q4wwXvPzOYHAEhsChbOU9BLYilO-7DBh8ZB5H/s1600/CDS.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhONLxExgY4Uthb3b6SJqrNlx_uiI3dGnDSH6vBM9QeYTPqwXnVaXsHXKEkXGfec9BIlO74_k6bXFJ-Wq0k61tZxGNgFU-L9G4yBJq2Bi4q4wwXvPzOYHAEhsChbOU9BLYilO-7DBh8ZB5H/s400/CDS.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Figure 14. Lunar Module panels.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The simulator is able to reproduce correctly the
control modes that are required to fly it. It's an unusual
control mode wherein you fly to in pitch and fly from in
yaw. While flying AOT <i><span style="color: #274e13;">[Alignment Optical Telescope]</span></i>, you
depend on the other crewmember to assure you that the roll
gimbal angle is staying at a reasonable value.<br />
<br />
The simulator
was never able to simulate accurately what you would see
through the Sun. We especially set up the AOT on the GetC
<i><span style="color: #274e13;">[Guidance and Control]</span></i> roof (MSC <i><span style="color: #274e13;">[Manned Spacecraft Center,
nowadays JSC, Johnson Space Center]</span></i>) to look at the actual
view. In addition, on the way to the Moon, we looked at the
Sun with the telescope; looked through the CSM telescope
with the Sun filter on to get used to what the filtered view
of the Sun would look like in the optics. It's somewhat
different in the telescope than in the AOT in color and
general appearance. I can't account for that, but it is
different.
<br />
<br />
I thought the numbers ought to be both closer to zero if we
didn't have any platform drift, or closer together in either
case. But we had quite a spread, so I'm not sure that the
check in general is really as good yet as it should be. In
other words, our variation was 0.08 degree between our
various measurements . The limit on the GO/NO-GO is 0.25.
So, we were essentially using up a third of our margin just
in variation between our marks. That's not really a good
enough procedure for this important check of the platform.
<u>This procedure, being a GO/NO-GO for the PDI needs
additional work prior to the next flight.
</u><br />
<br />
There are some alternative methods of understanding
platform drift, which we just did not have time to
implement. Perhaps the next flights will be able to look at
some of these alternatives and decide on an even better
method than the Sun check.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTo3HdFEC7aU354j10GMrg_7Gx5I0z9c65MQ0dCO60oaBS_awhkFlirGxxPjoy1A4Uy5JTePGOQ0qhj12A9kst60yg_0tmH48huhGN3r2IB3-k80Gdr8e2kjhB50SyanAAl__pzi2DZrcy/s1600/lm_panel01_prplnt_qty_mon.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTo3HdFEC7aU354j10GMrg_7Gx5I0z9c65MQ0dCO60oaBS_awhkFlirGxxPjoy1A4Uy5JTePGOQ0qhj12A9kst60yg_0tmH48huhGN3r2IB3-k80Gdr8e2kjhB50SyanAAl__pzi2DZrcy/s400/lm_panel01_prplnt_qty_mon.jpg" width="255" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 15. Lunar Module propellant quantity indicators on panel 1.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ALDRIN</u></i></b> - We turned the propellant quantity ON before DOI and
I believe the quantity light came on at that point, which
was expected as a possibility. Just recycling the switch off
and back on again would extinguish the light. The values
that we saw in fuel were about 94 and 95, which is what we
generally saw in the simulator. The oxidizer value was
somewhat lower than that.<br />
<br />
The simulator values were 95 and
95. I don't believe that there was sufficient time during
DOI for these to settle down completely. They did approach
the maximum numbers with a reading of approximately 94.
Anyway, they weren't dancing around the way we might have
been led to expect them to do.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPQIsSRCPhRaiJe5U6dWNsvDZIrSDkPnsL3hBgsKee_K59GaQ3mSMS_90VgJ6KwWHen19GYz9fHbTNFAy9ZOPjZBN7CZeQ0RIdxEO-i_LD2yxonbGRc4tR6ljgs6xcciJN2MGHpjgntsX0/s1600/lm-s-band-steerable.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPQIsSRCPhRaiJe5U6dWNsvDZIrSDkPnsL3hBgsKee_K59GaQ3mSMS_90VgJ6KwWHen19GYz9fHbTNFAy9ZOPjZBN7CZeQ0RIdxEO-i_LD2yxonbGRc4tR6ljgs6xcciJN2MGHpjgntsX0/s400/lm-s-band-steerable.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i style="color: #cc0000; font-size: medium;">Figure 16. Steerable S band antenna coordinates. Antenna pitch around antenna Y-axis (+255 degr/-75 degr), antenna yaw around antenna X-axis (+/- 87 degr). When both antenna pitch and yaw are zero the antenna is pointing LM forward (LM Z-axis). There is 45 degrees tilt between antenna and LM X- and Y-axis (around antenna z-axis). Both have the same Z-axis (LM forward).</i></td></tr>
</tbody></table>
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The pre-PDI attitude prevented good S-band <i><span style="color: #274e13;">[The
S band is a radio wave band with frequencies that range from
2 to 4 GHz]</span></i> high gain contact. We had continual
communications difficulty in this area until we finally
yawed the spacecraft right between 10 and 15 degrees to give
the high gain antenna more margin. This seemed to enable a
satisfactory high bit rate condition, but it did degrade our
ability to observe the surface through the LPD <i><span style="color: #274e13;">[Landing
Point Designator]</span></i> and make downrange and cross range
position checks. I don't think that our altitude checks were
significantly degraded.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - I can't explain why we had some dropouts there. The
angles, 220 in pitch and yaw 30, are not ones that would
lead you to believe they would give you trouble as far as
interferences from the LM structure. It seemed to me that
the initial locken was not bad. There is a certain rain
dance you had to go through each time you'd come around to
acquire lockon. Each time you'd have LOS <i><span style="color: #274e13;">[Loss Of Signal,
other meanings "Line Of Sight"]</span></i>, we'd usually be on the
OMNI's <i><span style="color: #274e13;">[In radio communication, an omnidirectional antenna
is a class of antenna which radiates radio wave power
uniformly in all directions]</span></i>.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3kxXWr3ktMDPLIjmYRj3m0yVuktXsOCLcVPYhlVqnaHaqDLiWctITHiKRE0SdIH5c73xGXR2vciZmauyWV8STdXwTJDyFjepVj28YG6keFka-FGlXlm0thzjgM8Q6GR-CLjUYUZ86ySoA/s1600/A11_LM_Antennas.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="366" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3kxXWr3ktMDPLIjmYRj3m0yVuktXsOCLcVPYhlVqnaHaqDLiWctITHiKRE0SdIH5c73xGXR2vciZmauyWV8STdXwTJDyFjepVj28YG6keFka-FGlXlm0thzjgM8Q6GR-CLjUYUZ86ySoA/s400/A11_LM_Antennas.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 17. Lunar Module antennas.</i></span></td></tr>
</tbody></table>
<br />
Of course, there's a choice of
forward or aft. Then you'd want to switch to SLEW and slew
in the proper values for the steerable before LOS on the
other side, the ground would like you to not break lock in
the slew mode, because in some cases the antenna would then
drive into the stops, So, approaching LOS, you'd switch to
maybe the aft OMNI and then you'd slew in some new numbers.
<br />
<br />
We'd make use of pitch 90 and yaw zero, to keep the antenna
away from the stops. Once you drive it to those values, then
you'd have to set in new numbers.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVieiH1kRxtEMg5PXsZHgI8gqcIVN68-W5ZoGTMuKF8AVnkPiTnWhNvD8bOaNLVphHBppSCQ8p3nB0mh9wXSwfYBgcQCFm3B4F6Lf-E5X6Pz4VIyOEek8HL7WZuFUzO2jVKwSukPIV_6z6/s1600/Comm_Antennas.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="292" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVieiH1kRxtEMg5PXsZHgI8gqcIVN68-W5ZoGTMuKF8AVnkPiTnWhNvD8bOaNLVphHBppSCQ8p3nB0mh9wXSwfYBgcQCFm3B4F6Lf-E5X6Pz4VIyOEek8HL7WZuFUzO2jVKwSukPIV_6z6/s400/Comm_Antennas.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 18. Lunar Module LM pilot's side, panel 12, Communications antennas section.</i></span></td></tr>
</tbody></table>
<br />
Coming around on the other side, you'd maybe switch from aft
to forward to pick up the ground. Once you picked them up,
you'd switch over to SLEW and you might have the right
values down there or you might have to tweak them up. In any
event, the initial contact would be made on one antenna; and
then, after you establish contact, you have to take the
chance of breaking it to switch over to the high gain.
Occasionally, we got the jump on them a little bit because
the ground was talking to the command module.<br />
<br />
We saw that we
had signal strength so I'd go ahead and try to lock on the
S-band. It is a rather involved process that you have to go
through. I didn't find that, if you left the antenna without
an auto lockon signal, it would have a tendency to drive to
the stops. At least from the indications, it didn't seem to
be moving so rapidly that you couldn't, within several
seconds if you knew what you were doing, stop it from where
it was going and prevent it from hitting the stops.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx2_i3k9zv2r3j08xr3ODyt2iTTfEN-_0mhXzmu7_chF0KWZfEe_qjUFTp0ZluECFwJkWxzsw83Irb2E3IZxE87hunaSHkV5anvIW5763dDxm507xiXEXdSJk8US3n7upuwbhyphenhyphenKcgw9voY/s1600/lm10-co15.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="395" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjx2_i3k9zv2r3j08xr3ODyt2iTTfEN-_0mhXzmu7_chF0KWZfEe_qjUFTp0ZluECFwJkWxzsw83Irb2E3IZxE87hunaSHkV5anvIW5763dDxm507xiXEXdSJk8US3n7upuwbhyphenhyphenKcgw9voY/s400/lm10-co15.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 19. Lunar Module LM pilot's side, panel 12.</i></span></td></tr>
</tbody></table>
<br />
We had two methods of computing altitude: one based on
relative motion from the CSM and the other based on angular
rate track of objects observed on the ground. We
superimposed the two of them on one graph and rearranged the
graph a little bit with some rather last-minute data
shuffling to give us something that the two of us could work
on at the same time and to give indication of the altitude
and its time history appeared to be. With the communications
difficulties that we were experiencing in trying to verify
that we had a good lockon at this point, I had the
opportunity to get only about two or three range-rate marks.
They appeared to give us a perilune altitude of very close
to 50 000 feet, as far as I could interpolate them on the
chart.
<br />
<br />
Those measurements give you altitude below the command
module, essentially. And, of course, there are some
modifications of the command module orbit, from the nominal
preflight orbit that you expect. The numbers either have to
be updated or you have to accept the error.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The measurements against the ground course were
indicative of altitude directly above the ground.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - The main purpose of the radar here was to confirm
that we were in the same ballpark, the same kind of an
orbit. And I think once you accomplish this several times,
then it's adequate to go on with the truer altitude
measuring device, which is from the ground.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVBRgVyLwaTJu-JDZKRIt_urrMoR1mngOszT-E70IDacIsMGVMRfAlB1uhRNnSSb6gbJ3ADFBxODF4iLaRP-wzRnZVrlN-FW-kvrJRlMmegMYFB190ViugDVH-1-x37iDvX62aD3htP8LT/s1600/antenna_apollo_11.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgVBRgVyLwaTJu-JDZKRIt_urrMoR1mngOszT-E70IDacIsMGVMRfAlB1uhRNnSSb6gbJ3ADFBxODF4iLaRP-wzRnZVrlN-FW-kvrJRlMmegMYFB190ViugDVH-1-x37iDvX62aD3htP8LT/s400/antenna_apollo_11.jpg" width="312" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 20. Honeysuckle Creek, Monday 21 July 1969. Hamish Lindsay writes: “This picture was taken of the HSK antenna tracking the Apollo 11 Lunar Module just before Armstrong took his first step onto the lunar surface. Tom Reid, the Station Director, sent me out to record the moment. It was a wet and cold mid-winter morning in Autralia – we were suffering sleet showers at the time, which you can see on the hills behind.”</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ARMSTRONG</u></i></b> - The ground measurements were very consistent. If
they made a horizontal line, it would indicate that you were
going to hit a particular perilune, in this case, 50 000
feet (in the middle of the chart). They didn't say that.
They were very consistent, but they came down a slope, which
said finally that our perilune was going to be 51 000 feet.<br />
<br />
It steadied out at about 54 000 feet here at the bottom and
our last point was 51 000 feet. This indicated that either
the ground was sloping; and, in fact, it was <u>about 10 000
feet lower</u> than the landing site where we started (which is
not consistent with the A-1 measurement that we made), or
that the <u>line of apsides was shifted</u> a little bit. So
actually perilune was coming a little bit before PDI.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2s-3B0kXl-I-BhZ0aFr_FcfP-BDBc7oioLkdD94eiEq4kuny7fT15vXJGjwnXlGiS5H8Sme_KNUEdd6sbQfnwV5z9dV3a6Z66mMYZgYwiCr9ao0-Sc3IuPCkmoKYfK0saZ-KCCNyuY3qx/s1600/apollo-usb-transponder.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2s-3B0kXl-I-BhZ0aFr_FcfP-BDBc7oioLkdD94eiEq4kuny7fT15vXJGjwnXlGiS5H8Sme_KNUEdd6sbQfnwV5z9dV3a6Z66mMYZgYwiCr9ao0-Sc3IuPCkmoKYfK0saZ-KCCNyuY3qx/s400/apollo-usb-transponder.jpg" width="387" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 21. Apollo Unified S Band Transponder.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">[<u>Unified S Band System Ranging Measurements</u><br /><br />Allocating uplink/downlink frequency pairs in a fixed ratio of 221/240 permitted the use of coherent transponders on the spacecraft. Coherent in this sense means there is a specific temporal relationship between the radio uplink and downlink signal phases. Then the phase or timing differences can be more easily analyzed to determine speed and distance between the spacecraft and tracking station.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The Apollo spacecraft receives the uplink carrier, and with a phase locked loop system, generates a downlink carrier related in frequency by the ratio 240/221. When no uplink was received, the transponder downlink carrier was generated from a local oscillator at the nominal frequency. Uplink signals were derived from extremely precise time and frequency standards, and received downlinks were analysed in phase and frequency based on these same standards. A precise "two way" doppler shift was measured, and the resulting speed between the tracking station and spacecraft could be determined to within a few centimeters per second. <br /><br />The Apollo Unified S Band System also provided distance measurements accurate to within 30 meters. The tracking station generated a pseudo-random-noise sequence at 994 kilobit/s and phase modulated it on the uplink carrier. The spacecraft transponder echoed this pseudo-noise signal back to earth on the downlink. The downlinked pseudo-noise was sent through a correlation process, meaning it was time-shifted to match the transmitted code, revealing the precise round trip light time to the spacecraft and back.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">This pseudo-random sequence repeated after about 5 seconds, enough to measure distance out to 540,000 miles. These ranging measurements consumed an appreciable fraction of the downlink capacity and were only needed for short periods, typically during handover from one ground station to the next. After the new uplink station achieved a 2-way coherent transponder lock with the spacecraft, the ranging signal was turned off and the range measurement was continually updated by doppler velocity measurements.]</span></i><br />
<br />
So we were actually reaching perilune a little bit before
PDI, which would tend to slope the curve that way. This was
all very encouraging that we were, in fact, going to hit the
guidance box so far as altitude was concerned from both
measurements (the radar measurements and the ground
measurements). But I was quite encouraged that these
measurements, made with the stopwatch, were consistent, in
fact.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - When you're able to smooth the numbers and plot a
reasonable number of than, your accuracy increases
considerably. I think the preflight estimates were something
on the order of a 6000-foot capability, and I think we
demonstrated a much better capability than that.
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicRyfbJVosDBBynCAitZoZdVTefgsZUGl4p_p1-zcD4VmmIl_ttDAz3dMony_4kmh_OOPbrsTdZHUyYz3v3rfRbb0UmkmturkO6gOpOtlsdOXc-PwtGzjgiNJ68FxdVJ_KGsh7Sbd8ntMy/s1600/ksc-69p-670.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEicRyfbJVosDBBynCAitZoZdVTefgsZUGl4p_p1-zcD4VmmIl_ttDAz3dMony_4kmh_OOPbrsTdZHUyYz3v3rfRbb0UmkmturkO6gOpOtlsdOXc-PwtGzjgiNJ68FxdVJ_KGsh7Sbd8ntMy/s400/ksc-69p-670.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Figure 22. July 24, 1969. President Nixon Greets the Returning Apollo 11 Astronauts. The Apollo 11 astronauts, left to right, Commander Neil A. Armstrong, Command Module Pilot Michael Collins and Lunar Module Pilot Edwin E. “Buzz” Aldrin Jr., inside the Mobile Quarantine Facility aboard the USS Hornet, listen to President Richard M. Nixon on July 24, 1969 as he welcomes them back to Earth and congratulates them on the successful mission. The astronauts had splashed down in the Pacific Ocean at 12:50 p.m. EDT about 900 miles southwest of Hawaii. Apollo 11 launched from Cape Kennedy on July 16, 1969, carrying the astronauts into an initial Earth-orbit of 114 by 116 miles. An estimated 530 million people watched Armstrong’s televised image and heard his voice describe the event as he took “…one small step for a man, one giant leap for mankind” on July 20, 1969.</i></span></td></tr>
</tbody></table>
</td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">17. PDI burn
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - Our downrange position appeared to be good at
the minus 3 and minus 1 minute point. I did not accurately
catch the ignition point because I was watching the engine
performance. But it appeared to be reasonable, certainly in
the right ballpark. Our cross range position was difficult
to tell accurately because of the skewed yaw attitude that
we were obliged to maintain for COMM <i><span style="color: #274e13;">[Communications to
Earth]</span></i>.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSH9CJfoRxEXNBZs4xH9OikpzKCO8lZZxSaeJV70WlNDtm4OLotuVO4yiPntmKKaQT5uVX7uJu86GhxWudSldfCGUMsAjnT0L_BFz6rj35rKg_FW122wR_UqRespYzBtapt8SeCX6ockT1/s1600/Automatic_Guidance.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="223" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSH9CJfoRxEXNBZs4xH9OikpzKCO8lZZxSaeJV70WlNDtm4OLotuVO4yiPntmKKaQT5uVX7uJu86GhxWudSldfCGUMsAjnT0L_BFz6rj35rKg_FW122wR_UqRespYzBtapt8SeCX6ockT1/s400/Automatic_Guidance.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 23. Lunar landing powered descent final LGC program phases. Either all automatic or to some level manual. But never fully manual (P67 has never been used during a real lunar landing) so computer assisted every lunar landing to the touch down.</i></span></td></tr>
</tbody></table>
<br />
However, the downrange position marks after ignition
indicated that we were long. Each one that was made
indicated that we were <u>2 or 3 seconds long in range</u>. The
fact that throttle down essentially came on time, rather
than being delayed, indicated that the computer was a little
bit confused at what our downrange position was. Had it
known where it was, it would have throttled down later,
based on engine performance, so that we would still hit the
right place. Then, it would be late throttling down so that
it would brake toward a higher throttle level prior to the
pitch over.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh99MLo75gXZqPgGnecR-sEF1kkwEoPrpMGR5V01pFoWwUe4StOrARkYzB0CYcUNFcSaCZLAavReAXJtZ42JWQbtGtfscecP8RpGWdkt2Tf8jDX2RnJRojDqg2S1o6Y8ff-qSI-aqwGt_4F/s1600/s69-41359.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh99MLo75gXZqPgGnecR-sEF1kkwEoPrpMGR5V01pFoWwUe4StOrARkYzB0CYcUNFcSaCZLAavReAXJtZ42JWQbtGtfscecP8RpGWdkt2Tf8jDX2RnJRojDqg2S1o6Y8ff-qSI-aqwGt_4F/s400/s69-41359.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 24. S69-41359 (10 Aug. 1969) -- Astronauts Michael Collins (left) and Edwin E. Aldrin Jr., are greeted by Dr. Robert R. Gilruth, director, Manned Spacecraft Center (MSC), and others upon their release from quarantine. The Apollo 11 crew left the Crew Reception Area (CRA) of the Lunar Receiving Laboratory (LRL) at 9 p.m., Aug. 10, 1969. While astronauts Neil A. Armstrong, commander, and Aldrin, lunar module pilot, descended in the Lunar Module (LM) "Eagle" to explore the Sea of Tranquility region of the moon, astronaut Collins, command module pilot, remained with the Command and Service Modules (CSM) "Columbia" in lunar orbit.</i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<b><span style="color: #0c343d;">23. LPD <i>[Landing Point Designator]</i> altitude</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The <u>LPD was not used until we were below 2500 feet</u>, and it was followed for some number of computation cycles. The landing point moved downrange with time as evidenced by successive LPD readings.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh82Nzkj5QOSYeooSA6kRND2g4hOe4onAfPABLqybMxLTQF4o6oVTPDFWZ19n11xLSJPtmYL2249x83-1vCdeGDZxJNRo-5kyJsal_b1nEfctvZDZlHYkT78oJPtJ9ppOePdys8i7KFkTmA/s1600/lpdin.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh82Nzkj5QOSYeooSA6kRND2g4hOe4onAfPABLqybMxLTQF4o6oVTPDFWZ19n11xLSJPtmYL2249x83-1vCdeGDZxJNRo-5kyJsal_b1nEfctvZDZlHYkT78oJPtJ9ppOePdys8i7KFkTmA/s400/lpdin.jpg" width="233" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 25. Landing Point Designator. If the pilot keeps the two windows patterns superimposed the computer can pinpoint the predicted landing point by turning LM and showing an angle measurement on the DSKY display.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">[<u>LPD Description</u></span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">At the beginning of the approach phase (P64) the LGC assumes an attitude such that the surface and the landing site are visible, and the commander visually scans the moon for the desired landing site. He will recognize it either by a marker placed by a previously landed spacecraft, as a visually identifiable landmark, or as an appropriate though unmarked site.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">Meanwhile, the computer orients the LGC such that the thrust points in the direction required for reaching the current site (that resulting from previous steering, if any, where the LM will land if there is no further steering) and uses the remaining degree of freedom (about the thrust axis) to keep the LPD superimposed on the current site. (There are two LPD scales and a double window, one scale is on the inside window and one on the outside window, to allow the commander to register his eye.) The computer also repetitively calculates and displays the complement of the look angle of the current site.</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">The LM pilot repetitively reads the angle from the display and repeats it to the commander. The commander identifies the current site by sighting through the LPD and observes the angular error, if any, between the current site and the desired site. If the angular error is significant, he manipulates the controller to cause the computer to redefine the current site closer to the desired site. Through repetition of the total process, the commander literally steers the current landing site into coincidence with the desired site.]</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<b><i><u>FCOD REP.</u></i></b> - Do you recall when you proceeded?<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - It was very shortly after we were going into P64.<br />
<br />
<b><i><u>ALDRIN</u></i></b> - We got P64 at 41 minutes 35 seconds <i><span style="color: #274e13;">[the automatic LGC switch from P63, BRAKING PHASE to P64, APPROACH PHASE, indicates throttle down]</span></i>; then you went MANUAL, ATTITUDE CONTROL.<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - I can't say whether that was before or after proceeding.<br />
<br />
<b><i><u>ALDRIN</u></i></b> - It wasn't too long after that,<br />
<br />
<ul>
<li>41:35 - P64,</li>
<li>42:05 - manual attitude control is good,</li>
<li>42:17 - program alarm.</li>
</ul>
<br />
What I'm wondering is did the proceed have anything to do with maybe generating same more activity which would cause the program alarm? We weren't in 16 68 at that point.<br />
<div>
<br /></div>
<i><span style="color: #274e13;">[VERB 16,</span></i><br />
<i><span style="color: #274e13;"> MONITOR DECIMAL IN R1 OR R1,R2 OR R1,R2,R3;</span></i><br />
<i><span style="color: #274e13;"><br /></span></i>
<i><span style="color: #274e13;">NOUN 68, 3COMP , NO LOAD, DEC ONLY,</span></i><br />
<i><span style="color: #274e13;"> SLANT RANGE TO LANDING SITE</span></i><br />
<i><span style="color: #274e13;"> xxxx.x NAUT MI<br /> TIME TO GO IN BRAKING PHASE</span></i><br />
<i><span style="color: #274e13;"> xxBxx MIN/SEC<br /> LR ALTITUDE - COMPUTED ALTITUDE</span></i><br />
<i><span style="color: #274e13;"> xxxxx. FEET ]</span></i><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - I have no recollection of that area.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx_B-cv803htx8dE_PCfsC19w5dAGKCesJgysl6UCR7vkVNfaGeRAI0rGgmaMYBdeu45kIMnla0Y86FyllIYuhu8KdIZa56kMzy3snfvYBN6qQ-dUWtu7pDXw5rDj2FBzOS2-UXX12TcPN/s1600/S69-41360+.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgx_B-cv803htx8dE_PCfsC19w5dAGKCesJgysl6UCR7vkVNfaGeRAI0rGgmaMYBdeu45kIMnla0Y86FyllIYuhu8KdIZa56kMzy3snfvYBN6qQ-dUWtu7pDXw5rDj2FBzOS2-UXX12TcPN/s400/S69-41360+.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 26. S69-41360, 08/10/69, Apollo 11 crewmen released from quarantine. Astronauts Michael Collins (left) and Edwin E. Aldrin Jr., are greeted by Dr. Robert R. Gilruth, Director, Manned Spacecraft Center, and others upon their release from quarantine. The Apollo 11 crew left the crew reception area of the Lunar Receiving Laboratory at 9 p.m., Aug. 10, 1969 (41359); Astronaut Neil A. Armstrong (center), is greeted by friends in the crew reception area of the Lunar Receiving Laboratory. Dr. Gilruth is pictured just to right of Armstrong. Donald K. Slayton, Director of Space Flight Crew Operations, is behind Armstrong (41360).</i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<b><span style="color: #0c343d;">24. Final approach and landing
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - Landmark visibility was very good. We had no
difficulty determining our position throughout all the
face-down phase of power descent. Correlating with known
positions, based on the Apollo 10 pictures, was very easy
and very useful.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - As I recall, there was a certain amount of manual
tracking being done at this time with the S-band antenna.
During the initial parts of power descent, the AUTO track
did not appear to maintain the highest signal strength. It
dropped down to around 3.7 and the ground wanted
reacquisition so I tweaked it up manually.
<br />
<br />
I got the impression that it was not completely impossible
to conduct a manual track throughout powered descent. You'd
not be able to do very much else besides that. I think it
would be possible to do, if you had sets of predetermined
values that you could set in.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnoSkgOLd1_VJ7Uo5rc-_l4bKbqV5puEMBBqoCnQpR8tSPRCGOWI9kUFKnQB9If3eeDju-QFiApZRl0h7R-qeNZG4WMMKfA_d9jExRSaQS7DYqd5H-yRxODAHzMRdXXAjwi2t3V71YeJVy/s1600/DSKY_ALT_LIGHT.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjnoSkgOLd1_VJ7Uo5rc-_l4bKbqV5puEMBBqoCnQpR8tSPRCGOWI9kUFKnQB9If3eeDju-QFiApZRl0h7R-qeNZG4WMMKfA_d9jExRSaQS7DYqd5H-yRxODAHzMRdXXAjwi2t3V71YeJVy/s400/DSKY_ALT_LIGHT.png" width="355" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 27. DSKY ALT light (when out indicates that the LR is working).</i></span></td></tr>
</tbody></table>
<br />
We did have S-band pitch and yaw angles immediately
following the yaw maneuver, and those that were acquired at
about 3000 feet . After the yaw, the S-band appeared to have
a little bit better communications. It was Just about at the
yaw-around maneuver (trajectory monitoring from the DSKY up
to that point agreed very closely especially in H-dot
<i><span style="color: #274e13;">[altitude rate]</span></i> and VI <i><span style="color: #274e13;">[inertial speed]</span></i> with the values we
had on the charts). It was almost immediately after yaw
around that the altitude light went out, indicating that we
had our landing radar acquisition and lockon.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The delta altitude <i><span style="color: #274e13;">[altitude correction from the
radar, enabled to the LGC manually by astronauts]</span></i> was -- 2600 or 2700,
I believe, is the number that I remember. I think it was
plus 2600 or 2700. The yaw around was slow. We had
inadvertently left the rate switch in 5 rather than 25, and
I was yawing at only a couple of degrees per second as
opposed to the 5 to 7 that we had planned. The computer
would not hold this rate of say, 1 to 2 deg/sec. It was
jumping up to 3 degrees and back, actually changing the sign
and stopping the roll rate.<br />
<br />
It was then that I clearly
realized that we weren't rolling as fast as was necessary
and I noted that we were on the wrong scale switch. So I
went to 25 and put in a 5-deg/sec command and it went right
around. However, this delayed it somewhat and consequently
we were in a slightly lower altitude at the completion of
the yaw around than we had expected to be so we were
probably down to about 39,000 or 40,000 feet at the time
when we had radar lockup, as opposed t o about 41,500 that
we expected to be.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - There are no discrepancies noted in any of the
systems that were checked throughout the first 4 minutes.
The RCS <i><span style="color: #274e13;">[Reaction Control System (propellant levels)]</span></i> was
surprisingly high in its quantity indications. The
supercritical <i><span style="color: #274e13;">[Lunar Module supercritical helium
pressurization system "SHe"]</span></i> did tend to rise a little bit
after ignition and then it started back down again. I don't
recall the maximum value that it reached. I guess the first
indications that we had of anything going wrong was probably
around 5 minutes, when we first started getting program
alarm activities.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - We probably ought to say we did have one program
alarm prior to this; sometime prior to ignition, that had
the radar in the wrong spot. In any case, as I remember,
we had a 500 series alarm <i><span style="color: #274e13;">[Radar alarms]</span></i> that said that the
radar was out of position, which I don't have any way of
accounting for. Certainly the switches were in the right
positions. They hadn't been changed since pre launch. But we
did, in fact, go to the descent position on the antenna and
leave it there for a half a minute or so, and then go back
to AUTO and that cleared the alarm. After 5 minutes into
descent, we started getting this series of program alarms;
generally of the series-that indicated that the computer was
being overloaded.<br />
<br />
Normally, in this time period, that is,
from P64 <i><span style="color: #274e13;">[THE LUNAR L</span></i><i><span style="color: #274e13;">ANDING, APPROACH PHASE]</span></i> onward, we'd be evaluating the landing site and
checking our position and starting LPD activity. However,
the concern here was not with the landing area we were going
into, but rather whether we could continue at all.
Consequently, our attention was directed toward clearing the
program alarms, keeping the machine flying, and assuring
ourselves that control was adequate to continue without
requiring an abort. Most of the attention was directed
inside the cockpit during this time period and in my view
this would account for our inability to study the landing
site and final landing location during final descent. It
wasn't until we got below 2000 feet that we were actually
able to look out and view the landing area.<br />
<br />
<b><i><u>ALDRIN</u></i></b> - Let me say something here that answers the question
that we had before about the AGS residuals on DOI. They were
0.1 before nulling and we nulled than to zero. X was minus
0.1, Y minus 0.4, Z minus 0.1, and we nulled X and Z to
zero. Looking at the transcripts, we did have considerable
loss of lock approaching PDI. And we did have to reacquire
manually several times. It looked like we had some
oscillations in the yaw angle on the antenna. The alarm that
we had was 500 and we went to descent 1 and proceeded in the
computer and then went back to AUTO again on the landing
radar switch. This was prior to ignition and the ground
recommended that we yaw right 10 degrees.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzI3O2dV0iz2dvRMcLvvbrFJOOVjnC2RYe6jXvJ4UUNfmprHv1yR036ipscLPsrukxGKzg3AlCPV3YaFVO0n5w098iVgiA1YKSQuuv15ui8Y9lLr_CKA4DChRJS_BO6P9JaE4GWb0tRDwN/s1600/lm-rr-csm-target-orientation.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="220" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzI3O2dV0iz2dvRMcLvvbrFJOOVjnC2RYe6jXvJ4UUNfmprHv1yR036ipscLPsrukxGKzg3AlCPV3YaFVO0n5w098iVgiA1YKSQuuv15ui8Y9lLr_CKA4DChRJS_BO6P9JaE4GWb0tRDwN/s400/lm-rr-csm-target-orientation.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 28. The RR was mainly meant to assist in finding the CSM during the ascent phase.</i></span></td></tr>
</tbody></table>
<b><i><u>SPEAKER</u></i></b> - You had the rendezvous radar on?<br />
<br />
<i><span style="color: #274e13;">[Later it was found that the reason for program alarms was that the RR was running on background and using too much CPU time. Also according to another source: "Repeated LGC jobs to process rendezvous radar were scheduled because a misconfiguration of the radar switches. Thus, the core sets got filled up and a 1202 alarm was generated. The 1201 that came later in the landing was because the scheduling request that caused the actual overflow was one that had requested a VAC area."]</span></i></div>
<div>
<br />
<b><i><u>ALDRIN</u></i></b> - The rendezvous radar was on, not through the
computer, but through its own AUTO track.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZENHPYDo5bwcucKs3kwPj6RkjxL873F_-RuOD4WkG6H4HNZ2bTjaaxDDSvvqbzQvG9co9YabsJSsbDQkXIYqBr9psmeh8zspGIRTqp4Tc2JHQ1KQebOZl3XAhTZPmF9nSrwloPmMcqnTs/s1600/lm-6-rendezvous-radar-antenna-assy.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="236" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZENHPYDo5bwcucKs3kwPj6RkjxL873F_-RuOD4WkG6H4HNZ2bTjaaxDDSvvqbzQvG9co9YabsJSsbDQkXIYqBr9psmeh8zspGIRTqp4Tc2JHQ1KQebOZl3XAhTZPmF9nSrwloPmMcqnTs/s400/lm-6-rendezvous-radar-antenna-assy.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 29. LM Rendezvous Radar Antenna Assembly.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ARMSTRONG</u></i></b> - We did not have the radar data feeding to the
computer in the LGC position; but, apparently, if you have
it in AUTO track, there's some requirement on the computer
time. This is the way we've been doing it in all
simulations. It was agreed on. We were in SLEW. Prior to
this time, we'd been in AUTO track until such time as we
started to lose lock in the pitch over. Then we went to
SLEW, isn't that right?
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGEqRlYjcuxfy9Nvnbo7K5p5lXqiadXFSzI2peVyztT47zrZdEr-4em0_bxL4kafT-FZ4TFDY5V6SqxUo4n6sUU980KA3WWv7UXJC4gONaSXMLVUIliR1RGzCCc2jRNOGmf63RmkymXNnH/s1600/groupshot_346x500.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="276" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGEqRlYjcuxfy9Nvnbo7K5p5lXqiadXFSzI2peVyztT47zrZdEr-4em0_bxL4kafT-FZ4TFDY5V6SqxUo4n6sUU980KA3WWv7UXJC4gONaSXMLVUIliR1RGzCCc2jRNOGmf63RmkymXNnH/s400/groupshot_346x500.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 30. Some MIT people behind the programs that landed the lunar modules. Front Row: Vince Megna, "Doc" Charles Stark Draper, Don Eyles, Dave Moore, Tony Cook. Back Row: Phil Felleman, Larry Berman, Allan Klumpp, Bob Werner, Robert Lones, Sam Drake.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ALDRIN</u></i></b> - Are you talking about the program alarms during the
descent? We've passed the point of having the rendezvous
radar in AUTO. We'd switched it over to SLEW at that point.
<br />
<b><i><u><br /></u></i></b>
<b><i><u>ARMSTRONG</u></i></b> - We were in SLEW with the circuit breakers in.
Radar was turned on, but it was in SLEW. In the early phases
of P64 <i><span style="color: #274e13;">[approach phase]</span></i>, <u>I did find time to go out of
AUTO-control and check the <i><span style="color: #274e13;">[semi]</span></i> manual control in both pitch and
yaw and found its response to be satisfactory.</u> I zeroed the
error needles and went back into AUTO. I continued the
descent in AUTO.<br />
<br />
At that point, we proceeded on the flashing
64 and obtained the LPD availability, but we did not use it
because we really weren't looking outside the cockpit during
this phase. As we approached the l5OO-foot point, the
program alarm seemed to be settling down and we committed
ourselves to continue.<br />
<br />
We could see the landing area and the
point at which the LPD was pointing, which was indicating we
were landing just short of a large rocky crater surrounded
with the large boulder field with very large rocks covering
a high percentage of the surface. I initially felt that that
might be a good landing area if we could stop short of that
crater, because it would have more scientific value to be
close to a large crater. Continuing to monitor LPD, it
became obvious that I could not stop short enough to find a
safe landing area.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpcnw7u0vvU8tWZAjgDFp2gAXolWElI3Hz1PY1tgDI8SlXD5fiLPM5jZZzMUmT1En13gKbYp67VpDOsa6novFTPw-WB0RkNRjGq9n0uj1UxiOLMy3kr5Lxf73aOK9G2z7mrWLPJj0FybLL/s1600/hawaii907240365V3_b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="325" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpcnw7u0vvU8tWZAjgDFp2gAXolWElI3Hz1PY1tgDI8SlXD5fiLPM5jZZzMUmT1En13gKbYp67VpDOsa6novFTPw-WB0RkNRjGq9n0uj1UxiOLMy3kr5Lxf73aOK9G2z7mrWLPJj0FybLL/s400/hawaii907240365V3_b.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 31. Crowds gathered to watch the Apollo 11 astronauts in their mobile quarantine facility on the move from Pearl Harbor to Hickam after being unloaded from the deck of the carrier Hornet. ADVERTISER LIBRARY PHOTO, July 24, 1969</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">25. Manual control/pitch over
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - We then went into <i><span style="color: #274e13;">[semi]</span></i> MANUAL and pitched the vehicle
over to approximately zero pitch and continued. I was in the
20- to 30- ft/sec horizontal-velocity region when crossing
the top of the crater and the boulder field.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHq1cLm7UUOL5IVtyo4xdG3d2c_ziipWtnMGeSpSN1Ny7TOy5w-ilgB7FAi80cR2zmVpmAV0ukv5Zxt_O1qw3YYgSfgJDd8bGHTNItnm-s_TClvf_SVC7BH_pp_-V8Ec83VAJenISi0cDd/s1600/Lunar_Module_Landing_Controls.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHq1cLm7UUOL5IVtyo4xdG3d2c_ziipWtnMGeSpSN1Ny7TOy5w-ilgB7FAi80cR2zmVpmAV0ukv5Zxt_O1qw3YYgSfgJDd8bGHTNItnm-s_TClvf_SVC7BH_pp_-V8Ec83VAJenISi0cDd/s400/Lunar_Module_Landing_Controls.png" width="330" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 32. Using the ROD switch and turning the LGC to a semi manual mode the commander can fly the LM like it was a helicopter.</i></span></td></tr>
</tbody></table>
<br />
I then
proceeded to look for a satisfactory landing area and the
one chosen was a relatively smooth area between some sizeable craters and a ray-type boulder field. I first noticed
that we were, in fact, disturbing the dust on the surface
when we were at something less than 100 feet; we were
beginning to get a transparent sheet of moving dust that -
obscured visibility a little bit. As we got lower, the
visibility continued to decrease.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvOPPCUiD6Iy3KT3cUsI9qyg7fU5F8uJ4i-OZilY5-_0m7jppCMo37C3LfpsYimtl8SfpVWubzP4ZYn6oVoTjNo9vUimTekV4f7hnVYLPEKq0u_Gm9ZveEWLOTX_GeksfQeC5L76_NIBcv/s1600/moon-dust-8687-ii.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="275" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvOPPCUiD6Iy3KT3cUsI9qyg7fU5F8uJ4i-OZilY5-_0m7jppCMo37C3LfpsYimtl8SfpVWubzP4ZYn6oVoTjNo9vUimTekV4f7hnVYLPEKq0u_Gm9ZveEWLOTX_GeksfQeC5L76_NIBcv/s400/moon-dust-8687-ii.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 33. Lunar dust.</i></span></td></tr>
</tbody></table>
<br />
I don't think that the
altitude determination was severely hurt by this blowing
dust, but the thing that was confusing to me was that it was
hard to pick out what your lateral and downrange velocities
were, because you were seeing a lot of moving dust that you
had to look through to pick up the stationary rocks and base
your translational velocity decisions on that. I found that
to be quite difficult. I spent more time trying to arrest
translational velocities than I thought would be necessary.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc0PkTJXLGRFzarHXA0CqNcn0xt4wIuhahUwd1IN3KMqcXMGroThkegnxL5aCerAxGy744l_shj4sB2U3jQukqJurJpLwz1WVCFuuZZ983_-49JtRwLZq6sOwuL65ipzfrJYdhDhap3w-L/s1600/LM_Landing_945.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgc0PkTJXLGRFzarHXA0CqNcn0xt4wIuhahUwd1IN3KMqcXMGroThkegnxL5aCerAxGy744l_shj4sB2U3jQukqJurJpLwz1WVCFuuZZ983_-49JtRwLZq6sOwuL65ipzfrJYdhDhap3w-L/s400/LM_Landing_945.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 34. Lunar landing just before touch down.</i></span></td></tr>
</tbody></table>
<br />
As we got below 30 feet or so, I had selected the final
touchdown area. For same reason that I am not sure of, we
started to pick up left translational velocity and a
backward velocity. That's the thing that I certainly didn't
want to do, because you don't like to be going backwards,
unable to see where you're going.<br />
<br />
So I arrested the backward
rate with same possibly spastic control motions, but I was
unable to stop the left translational rate . As we
approached the ground, I still had a left translational rate
which made me reluctant to shut the engine off while I still
had that rate. I was also reluctant to slow down my descent
rate anymore than it was or stop because we were close to
running out of fuel. We were hitting our abort limit.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0d4cOnvWf83eF26HbRKSzcTUGb8KL2A6ER1RIQ6TuHQ1b1_uas8K_SYuCeocRsZKZSJofh74wzKkG2YwMaXG8vhe4I0Fb6yj5JXUis8f5TzvHXmN-gntNcRwBX9Az7ysoDRrh3eMe-nan/s1600/ap11-69-H-1421.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="303" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg0d4cOnvWf83eF26HbRKSzcTUGb8KL2A6ER1RIQ6TuHQ1b1_uas8K_SYuCeocRsZKZSJofh74wzKkG2YwMaXG8vhe4I0Fb6yj5JXUis8f5TzvHXmN-gntNcRwBX9Az7ysoDRrh3eMe-nan/s400/ap11-69-H-1421.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption"><span style="color: #cc0000; font-size: small;"><i>Figure 35. New York welcomes the Apollo 11 crew with a ticker tape parade on August 13th 1969. Courtesy of Kipp Teague’s Apollo Image Gallery.</i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">28. Touchdown
</span></b><br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - We continued to touchdown with a slight left
translation. I couldn't precisely determine touchdown. Buzz
called lunar contact, but I never saw the lunar contact
lights <i><span style="color: #274e13;">[lunar contact whiskers are connected to the lunar
contact indicator lights in the cockpit]</span></i>.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - I called contact light.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaDNaT4Wpfbri90RRNqi3SDJlrSLM6SF-fZ4PC6rCkMZuzbLdt1hGHHEciEZRyOEHsv-2KLJ1a_S_oMUDjt68SeLNuGVdPEQ8ORYL01wyhtx1A5COZeRkdMXc8stmB95wLOqfCCbR-ACDG/s1600/lunar_module_panel3_contactlight.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="153" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaDNaT4Wpfbri90RRNqi3SDJlrSLM6SF-fZ4PC6rCkMZuzbLdt1hGHHEciEZRyOEHsv-2KLJ1a_S_oMUDjt68SeLNuGVdPEQ8ORYL01wyhtx1A5COZeRkdMXc8stmB95wLOqfCCbR-ACDG/s400/lunar_module_panel3_contactlight.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 36. One of the many lunar contact lights blue on the far right in an illuminated LM panel 3.</i></span></td></tr>
</tbody></table>
<br />
<b><i><u>ARMSTRONG</u></i></b> - I'm sure you did, but I didn't hear it, nor did
I see it. I heard you say something about contact, and I was
spring loaded to the stop engine position, but I really
don't know whether we had actually touched prior to contact
or whether the engine off signal was before contact.<br />
<br />
In any
case, the engine shutdown was not very high above the
surface. The touchdown itself was relatively smooth; there
was no tendency toward tipping over that I could feel. <u>It
just settled down like a helicopter on the ground and
landed.
</u><br />
<br />
<b><i><u>ALDRIN</u></i></b> - We had a little right drift, and then, I guess just
before touchdown, we drifted left.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - I think I was probably over controlling a little
bit in lateral. I was confused somewhat in that I couldn't
really determine what my lateral velocities were due to the
dust obscuration of the surface. I could see rocks and
craters through this blowing dust. It was my intention to
try and pick up a landing spot prior to the 100-foot mark
and then pick out an area just beyond it such that I could
keep my eyes on that all the way down through the descent
and final touchdown.<br />
<br />
I wouldn't, in fact, be looking at the
place I was going to land; I would be looking at a place
just in front of it. That worked pretty well, but I was
surprised that I had as much trouble as I did in determining
translational velocities. I don't think I did a very good
job of flying the vehicle smoothly in that time period. I
felt that I was a little bit erratic.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk4LyabsNfzqXeyuaOzosPOdsCFvQSpJdbEOQ_La86n9ICWlVXyVGeFKt4rC2CMgmUO1Rt1GME1xwzLOzfexez0jeb5GJcPt0GNhrObIAM1OVkiJVaJFf6z6cqwJaDukGOX4bhjsIrYTuP/s1600/Apollo_11_LM_Descent_Hover_Phase.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="336" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgk4LyabsNfzqXeyuaOzosPOdsCFvQSpJdbEOQ_La86n9ICWlVXyVGeFKt4rC2CMgmUO1Rt1GME1xwzLOzfexez0jeb5GJcPt0GNhrObIAM1OVkiJVaJFf6z6cqwJaDukGOX4bhjsIrYTuP/s400/Apollo_11_LM_Descent_Hover_Phase.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 37. Apollo 11 LM telemetry shows throttle oscillations during the last 140 s before touch down.</i></span></td></tr>
</tbody></table>
<br />
<i><span style="color: #274e13;">[During the last 140 seconds of the PDI burn (hover phase), a series of large oscillating-throttle changes occurred (figure above). These changes were approximately 15 percent peak-to-peak about a nominal throttle setting of approximately 26 percent.<br /><br />There are 2 explanations:</span></i><br />
<ol>
<li><i><span style="color: #274e13;">Large and rapid changes in vehicle attitudein pitch during the final phases of landing (Eyles: "Armstrong switched the autopilot from AUTO to ATT HOLD to manually fly over the rocky area") caused centrifugal accelerations on the inertial- measurement-unit accelerometers located at the top of the ascent stage high above the vehicle c.g., thereby giving a false indication of vertical acceleration. This false indication caused the lunar guidance computer to command a throttle change to compensate for an unreal change in vertical acceleration. Later, this problem was investigated under the analysis of the guidance and control system.</span></i></li>
<li><i><span style="color: #274e13;">The oscillatory character of the P66 throttle command was apparently due to the actual value of the descent engine time constant being smaller than that assumed. And so it was: the performance of the descent engine had been improved, but the ICD was not modified accordingly. The actual time lag for the descent engine was only about 0.075 seconds when it was assumed to be 0.3 seconds. Despite of that both Apollo 11 and 12 flew with 0.2 seconds of compensation for a 0.3 second throttle delay. As a result the throttle was barely stable (until later missions 14, 15, 16 and 17). </span></i></li>
</ol>
<i><span style="color: #274e13;"><i><span style="color: #274e13;">Both confirm that it was not much due to Armstrong's handling.</span></i><i><span style="color: #274e13;">]</span></i></span></i><br />
<div>
<i><span style="color: #274e13;"><i><span style="color: #274e13;"><br /></span></i></span></i></div>
<i><span style="color: #274e13;">
</span></i>
<b><i><u>ALDRIN</u></i></b> - I was feeding data to him all the time. I don't
know what he was doing with it, but that was raw computer
data.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - The computer data seemed to be pretty good
information, and I would say that my visual perception of
both altitude and altitude rate was not as good as I thought
it was going to be. In other words, I was a little more
dependent on the information. I think I probably could have
made a satisfactory determination of altitude and altitude
rate by eye alone, but it wasn't as good as I thought it was
going to be, and I think that it's not nearly so good as it
is here on Earth.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - I got the impression by just glimpsing out that we
were at the altitude of seeing the shadow. Shortly after
that, the horizon tended to be obscured by a tan haze. This
may have been just an impression of looking down at a
45-degree angle. The depth of the material being kicked up
seemed to be fairly shallow.<br />
<br />
In other words, it was scooting
along the surface, but since particles were being picked up
and moved along the surface, you could see little rocks or
little protuberances caning through this, so you knew that
it was solid there. It wasn't obscured to that point, but it
did tend to mask out your ability to detect motion because
there was so much motion of things moving out. There were
these few little islands that were stationary. If you could
sort that out and fix on those, then you could tend to get
the impression of being stationary. But it was quite
difficult to do.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - It was a little bit like landing an airplane
when there's a real thin layer of ground fog, and you can
see things through the fog. However, all this fog was moving
at a great rate which was a little bit confusing.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - I would think that it would be natural looking out
the left window and seeing this moving this way that <u>you
would get the impression of moving to the right</u>, and you
counteract by going to the left, which is how we touched
down.
<br />
<br />
<b><i><u>ARMSTRONG</u></i></b> - Since we were moving left, we were yawed
slightly to the left so I could get a good view of where we
were going. I think we were yawed 13 degrees left ; and,
consequently, the shadow was not visible to me as it was
behind the panel, but Buzz could see it.<br />
<br />
Then I saw it in
the final phases of descent. I saw the shadow came into
view, and it was a very good silhouette of the LM at the
time I saw it. It was probably a couple of hundred feet out
in front of the LM on the surface. This is clearly a useful
tool, but I just didn't get to observe it very long.
<br />
<br />
<b><i><u>ALDRIN</u></i></b> - Here's a log entry:
<br />
<br />
<ul>
<li>+46 seconds, 300 feet,</li>
<li>next min + 4 seconds.
Watch your shadow, and at</li>
<li>+16 seconds, 220 feet.</li>
</ul>
<br />
So I would estimate that I called out that shadow business
at around 260 feet, and it was certainly large at that
point. I would have said that at 260 feet the shadow would
have been way the hell and gone out there, but it wasn't. It
was a good-size vehicle. I could tell that we had our gear
down and that we had an ascent and a descent stage.<br />
<br />
Had I
looked out sooner, I'm sure I could have seen something
identified as a shadow at 400 feet; maybe higher, I don't
know. But anyway, at this altitude, it was usable. Since the
ground is moving away, it might be of some aid. But of
course, you have to have it out your window."<br />
<br />
<i><span style="color: #274e13;">[Continues to "Lunar Surface" debriefing, see /1/ for more..]</span></i><br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5gRBfQLsn47kX_dhvXn-Go2FfLTS8jIdnKmG-IY0CWDdcGXPfqH4foUI9SXeFMLKY2PV8-s9MecaXHM5NmKF65j4KxgresnTqkNRAUanD54r1-iFhWpcV9zUq0Y7g86gUheTsoU6Qi38n/s1600/LM_AScent_Stage-C.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5gRBfQLsn47kX_dhvXn-Go2FfLTS8jIdnKmG-IY0CWDdcGXPfqH4foUI9SXeFMLKY2PV8-s9MecaXHM5NmKF65j4KxgresnTqkNRAUanD54r1-iFhWpcV9zUq0Y7g86gUheTsoU6Qi38n/s400/LM_AScent_Stage-C.png" width="397" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Figure 38. An illustration of the LM ascent stage where the 2nd pilot is chilling out. That might be after the landing?</i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<b><span style="color: #0c343d;">RESOURCES
</span></b><br />
<br />
/1/ APOLLO 11 TECHNICAL CREW DEBRIEFING,<br />
July 31, 1969, VOL I,<br />
Lunar Descent Sections,<br />
CONFIDENTIAL - GROUP 4,<br />
Downgraded at 3-year intervals,<br />
declassified after 12 years
<br />
<br />
/2/ Internet<br />
<br />
<div style="text-align: center;">
* * *
</div>
<br /></div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-10872443551761248832016-12-31T20:46:00.000+00:002018-01-01T05:28:13.919+00:00DSKY Interface (Part 13, Apollo Control Systems) (DSKY I/O Interface, Apollo Guidance Computer)
<br />
<br />
<span style="color: #4c1130;"><i>[This article describes how the Apollo Guidance Computer (AGC) was connected to the Display and Keyboard Unit (DSKY). This is rather detailed description about the hardware and gives some light about how various devices were connected to the AGC. Since the connection was digital and parallel no special arrangements was required as with the more sensitive analog interfaces. The text is mainly from reference /1/.]</i></span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhawx1or13OI_vSa6wYnRkMjaP6Zy0dE9tekjhk-xEW0Y9xsZHwl08qs2VDmCj-25gmWeH0WVkbzippQlsyHSMalFB_O1QyrkpJoX4nH5ZAJzVTZKL12DJIMPAizcjN1djv2sY1tLqjglRw/s1600/agc2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhawx1or13OI_vSa6wYnRkMjaP6Zy0dE9tekjhk-xEW0Y9xsZHwl08qs2VDmCj-25gmWeH0WVkbzippQlsyHSMalFB_O1QyrkpJoX4nH5ZAJzVTZKL12DJIMPAizcjN1djv2sY1tLqjglRw/s400/agc2.jpg" width="377" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. DSKY (Apollo Guidance Computer Display and
Keyboard)</span></i></span></td></tr>
</tbody></table>
<a name='more'></a><h4>
I/O INTERFACE OF THE DSKY (KEYBOARD AND DISPLAY) /1/
</h4>
<br />
"The external inputs to the Keyboard and Display System
Program are the direct-wire Keyboard (manual astronaut entries) and the Uplink (from the MCC Houston and Earth's MSFN network via the CM or LM receiver). The
output is the Electroluminescent Display Panel (located in front of astronauts).
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpfAqOPptZdmKH9dy64dlk0CELFQ2jv0YsCU2Sn2lVsl4QrpWmop0_UWTxVRSrhxKfTGI8bAmNvnkOVYfIwlOwkycmpjphBZ2hV4QvNYLgPgFAI551wRlBZ0jtnIh3MOH4fkBNyzBkwbWB/s1600/LM+Computer+Interfaces.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpfAqOPptZdmKH9dy64dlk0CELFQ2jv0YsCU2Sn2lVsl4QrpWmop0_UWTxVRSrhxKfTGI8bAmNvnkOVYfIwlOwkycmpjphBZ2hV4QvNYLgPgFAI551wRlBZ0jtnIh3MOH4fkBNyzBkwbWB/s400/LM+Computer+Interfaces.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 2. LGC Interfaces. AGC (LGC) in the middle and various I/O devices around it.</span></i></span></td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4nyItFC_EGPVBWRgLRYiWR840q_-8Cl18EN2KpwX3LNV8wdv4VjTEzplDj9tIxCEOoA23RNEcr5EWxWnjij8PRRWVsQo8rL_clWQMQ-W30qFUlCVaJe1mEdfTfP-POF7GTLxWq-kqtTs5/s1600/DskyDiagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="193" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4nyItFC_EGPVBWRgLRYiWR840q_-8Cl18EN2KpwX3LNV8wdv4VjTEzplDj9tIxCEOoA23RNEcr5EWxWnjij8PRRWVsQo8rL_clWQMQ-W30qFUlCVaJe1mEdfTfP-POF7GTLxWq-kqtTs5/s400/DskyDiagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. DSKY Interfeace is mainly via two 15 bit words (I/O Channels), one for output and one for input. Additionally channel 11 is used for status lights and channel 16 for the navigation keyboard in CM.</span></i></span></td></tr>
</tbody></table>
<br />
<span style="color: #274e13;"><i>[For a general idea how a DSKY works with an AGC look the following video.</i></span><br />
<span style="color: #274e13;"><i> <a href="https://youtu.be/Qj2IETkScWA" target="_blank">YouTube video: "DSKY AGC"</a> ]</i></span><br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqdq2eW5-effK2TXB2jWdgSuEH-hSdy984WI3KMeRMzFI_v7Fp1K3RwNJRMbo8z0hDvdk9q_ab3u-KVAFewjW_jNqYLM4ndjkQE5Bme4jABia6Ph4nxIHL9lfPMknLOcfM6lGl7lVqUtpf/s1600/DSKY_LGC_Interface.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqdq2eW5-effK2TXB2jWdgSuEH-hSdy984WI3KMeRMzFI_v7Fp1K3RwNJRMbo8z0hDvdk9q_ab3u-KVAFewjW_jNqYLM4ndjkQE5Bme4jABia6Ph4nxIHL9lfPMknLOcfM6lGl7lVqUtpf/s400/DSKY_LGC_Interface.png" width="252" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 4. LGC/DSKY Signal reference numbers and names vs. channels. Grumman original drawing.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>1. Direct-wire Keyboard
</b></span><br />
<br />
"The Keyboard contains the following characters:<br />
<ul>
<li>VERB,</li>
<li>NOUN,</li>
<li>+,</li>
<li>-,</li>
<li>the numerical characters from 0 through 9,</li>
<li>CLEAR,</li>
<li>ENTER,</li>
<li>RESET, and</li>
<li>KEY RELEASE.</li>
</ul>
Each of the characters is
represented by a 5-bit binary code (see below).<br />
<br />
<br />
<table align="center" bgcolor="yellow" border="1" cellpadding="10">
<tbody>
<tr><td><u>KEY</u></td><td><u>CODE</u></td></tr>
<tr><td>0</td><td>1 0 0 0 0</td></tr>
<tr><td>1</td><td>0 0 0 0 1</td></tr>
<tr><td>2</td><td>0 0 0 1 0</td></tr>
<tr><td>3</td><td>0 0 0 1 1</td></tr>
<tr><td>4</td><td>0 0 1 0 0</td></tr>
<tr><td>5</td><td>0 0 1 0 1</td></tr>
<tr><td>6</td><td>0 0 1 1 0</td></tr>
<tr><td>7</td><td>0 0 1 1 1</td></tr>
<tr><td>8</td><td>0 1 0 0 0</td></tr>
<tr><td>9</td><td>0 1 0 0 1</td></tr>
<tr><td>VERB</td><td>1 0 0 0 1</td></tr>
<tr><td>RESET</td><td>1 0 0 1 0</td></tr>
<tr><td>KEY RELEASE</td><td>1 1 0 0 1</td></tr>
<tr><td>+</td><td>1 1 0 1 0</td></tr>
<tr><td>-</td><td>1 1 0 1 1</td></tr>
<tr><td>ENTER</td><td>1 1 1 0 0</td></tr>
<tr><td>CLEAR</td><td>1 1 1 1 0</td></tr>
<tr><td>NOUN</td><td>1 1 1 1 1</td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
<span style="color: #cc0000;"><i><span style="font-size: small;">Table 1. The keyboard sends these keycodes to the AGC among others.
</span></i></span></div>
<br />
<br />
The
Keyboard code is transmitted to the computer over a 5-wire
link and is placed into bits 1 - 5 of the appropriate input
channel.
<br />
<br />
<ul>
<li>CSM - Each depression of a button on the Main Keyboard
activates <u><i>INTERRUPT KEYRUPT1</i></u>, and places the key
code into Channel 15. The Navigation Keyboard
activates <u><i>INTERRUPT KEYRUPT2</i></u>, and places the key
code into Channel 16.</li>
<li>LM - Each depression of a Keyboard button activates
<u><i>INTERRUPT KEYRUPT1</i></u>, and places the key code into
Channel 15.
</li>
</ul>
<span style="color: #274e13;"><i>[Notice that all channels are given here as octal numbers .. as most numbers in the Apollo AGC programming practice. So channel 016 is actually 8+6 = 14 in decimal and 0x0E in hexadecimal. Octal is an oddity for many current programmers who are more used to the hexadecimal coding since microprocessors 1970's. ]</i></span><br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4olH9LDXi45UEDXor2xj6n_oPOPUMnLF4IToj-2PVrVASLy9x5E3z6_CY0npZoorwfpNQOPzJhJ7v5jDNI-ww4c6Im_VXT5Y87YkMkfvZWeZxJdb2Tpq_9H3swTqKJ8u5mnk4fNhbIuqN/s1600/14_lgc_dsky5.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="311" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4olH9LDXi45UEDXor2xj6n_oPOPUMnLF4IToj-2PVrVASLy9x5E3z6_CY0npZoorwfpNQOPzJhJ7v5jDNI-ww4c6Im_VXT5Y87YkMkfvZWeZxJdb2Tpq_9H3swTqKJ8u5mnk4fNhbIuqN/s400/14_lgc_dsky5.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 5. Most DSKY keys send keycodes, but some keys are directly connected (the more important ones). In different source documents the signals are different and reflects the evolution of the project during the 10 years period it was expanded.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The appropriate KEYRUPT program picks up the key code and
enters a request to the Executive Routine for the program
which decodes and digests the key code (CHARIN). Then a
RESUME is executed, terminating the KEYRUPT."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwHhiLTCN3I6qcGZF9Eonrlh7VjTyujlQyihfi-9K20UCBSnNN0FDGf3LIVBgsl0o9DNIDih79YHZ_IuVjN3PNsGuA5yaNQ4wLZAb_NdarsbrhJwnneFWgzIfH7rnO0dE4lJkq7l2affk7/s1600/6375049637_afc0369cdc.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwHhiLTCN3I6qcGZF9Eonrlh7VjTyujlQyihfi-9K20UCBSnNN0FDGf3LIVBgsl0o9DNIDih79YHZ_IuVjN3PNsGuA5yaNQ4wLZAb_NdarsbrhJwnneFWgzIfH7rnO0dE4lJkq7l2affk7/s400/6375049637_afc0369cdc.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 6. The DSKY connector seen. DSKY was rather deep and heavy: 17.5 pounds, 8" x 7" x 7" compared to the today's plastic standards.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #0c343d;"><b>2. UPLINK Inputs
</b></span><br />
<br />
"The Uplink is the digital telemetry system which sends
information from the ground to the airborne computer.
<br />
<br />
Each time a word is received by the Uplink, <u><i>INTERRUPT UPRUPT</i></u>
is activated. UPRUPT picks up the transmitted code (these
codes are the same as key codes) and enters a request to the
Executive Routine for the program which decodes and digests
the key code (CHARIN). Then a RESUME is executed,
terminating the UPRUPT.
<br />
<br />
Note that CHARIN makes no distinction between inputs from
the Keyboard and inputs from the Uplink.
<br />
<br />
There is a toggle switch which is used either to accept
Uplink inputs, or to block the Uplink. In the blocked
position, the operator has chosen not to accept any keyboard
type of input from the ground.
<br />
<br />
These codes enter the computer through bits 1-5 of either
channel 15 or 16 (CSM or LM). The MSB is placed in bit 5;
the LSB, in bit 1.<br />
<br />
<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1KUhQkWhDun2vDUx2voJP4dO2uUv4cboC4k2oyN6zxQM0x-4Fk5TnmoPIW7xa6z8WwERLqfNGBRZJ0thK7noCGTehR_oirJEhye5BZHA4xxblTVwfFzF_n0sRc_iasouLIeH4yIPlO6-Z/s1600/6375049567_d29a766085.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="262" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi1KUhQkWhDun2vDUx2voJP4dO2uUv4cboC4k2oyN6zxQM0x-4Fk5TnmoPIW7xa6z8WwERLqfNGBRZJ0thK7noCGTehR_oirJEhye5BZHA4xxblTVwfFzF_n0sRc_iasouLIeH4yIPlO6-Z/s400/6375049567_d29a766085.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 7. Close view of the DSKY connector to the AGC. The bike tire valve is for pressurizing dry nitrogen, a
common feature in Block II electronics to remove sparking fire risk in
the pure oxygen cabin environment.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>3. The Display Panel
</b></span><br />
<br />
<i><b>Description
</b></i><br />
<br />
The Display Panel consists of 24 electroluminescent sections
arranged as in Fig. 8 below.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZIZ3dZqhVzqybw8TgsRRZDZ-0dnKkGqnDKFFE1eHTo71wKVdIAuXrm9Gmm4WmZSL7OYuwiJatQegdE8tCLF-lJGFo3MYddaGoMXg0fZ2Y0VGUACwCjS0ZJ6oEgW6y0CJ7tb571EXc5kXw/s1600/Display_Panel.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZIZ3dZqhVzqybw8TgsRRZDZ-0dnKkGqnDKFFE1eHTo71wKVdIAuXrm9Gmm4WmZSL7OYuwiJatQegdE8tCLF-lJGFo3MYddaGoMXg0fZ2Y0VGUACwCjS0ZJ6oEgW6y0CJ7tb571EXc5kXw/s400/Display_Panel.png" width="347" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 8. Display Panel. The 24 electroluminescent sections (7-segments) in the DSKY display panel and their names.</span></i></span></td></tr>
</tbody></table>
<br />
Each section is capable of displaying any decimal character
or remaining blank, except the 3 sign sections (RlS, R2S,
R3S). These display a plus sign, a minus sign, or a blank.
The numerical sections are grouped to form 3 data display
registers, each of 5 numerical characters; and 3 control
display registers, each of 2 numerical characters, The data
display registers are referred to as <b><i>R1</i></b>, <i><b>R2</b></i>, <i><b>R3</b></i>. The control
display registers are known as <i><b>Verb</b></i>, <i><b>Noun</b></i>, and <i><b>Major Mode</b></i>
(Program or phase number).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjA0taEKkVpnkGY4oCT5n_r3Ghtfj-aYRI19dNveLCb5GYNVVKYq12K5FerwDaRaRVbIfpzmYN8Nc_-BfRMThj2kkvVq7Rta5g6xqRV0frKm92paBRUlQXbBjYmmAKUJmP530BtWo6yk2C3/s1600/14_lgc_dsky3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjA0taEKkVpnkGY4oCT5n_r3Ghtfj-aYRI19dNveLCb5GYNVVKYq12K5FerwDaRaRVbIfpzmYN8Nc_-BfRMThj2kkvVq7Rta5g6xqRV0frKm92paBRUlQXbBjYmmAKUJmP530BtWo6yk2C3/s400/14_lgc_dsky3.png" width="312" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 9. LGC sends all data to DSKY via two 15 bit channels. One for the 7-segments and one for the status lights. It is known that some spacecraft relays and I/O devices are also controlled via these channels.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Major Mode (Program) display register is used to
indicate which phase of the mission or large system program
is operating. The Verb and Noun display registers are used
to indicate the activity of a smaller class of programs,
such as displays, loads, etc. These may be initiated by
keyboard action, or from within the computer by program
action.
<br />
<br />
<br />
<br />
<i><b>Activation.
</b></i><br />
<br />
Each Display Panel character is controlled by a group of 5
latching relays. Once these relays are activated, the
appropriate character remains visible on the Display Panel
until the state of these relays is changed. The 5-bit relay
codes for each numerical character are listed below.
<br />
<br />
<table align="center" bgcolor="yellow" border="1" cellpadding="10">
<tbody>
<tr><td><u>DISPLAY</u></td><td><u>CODE</u></td></tr>
<tr><td>Blank</td><td>0 0 0 0 0</td></tr>
<tr><td>0</td><td>1 0 1 0 1</td></tr>
<tr><td>1</td><td>0 0 0 1 1</td></tr>
<tr><td>2</td><td>1 1 0 0 1</td></tr>
<tr><td>3</td><td>1 1 0 1 1</td></tr>
<tr><td>4</td><td>0 1 1 1 1</td></tr>
<tr><td>5</td><td>1 1 1 1 0</td></tr>
<tr><td>6</td><td>1 1 1 0 0</td></tr>
<tr><td>7</td><td>1 0 0 1 1</td></tr>
<tr><td>8</td><td>1 1 1 0 1</td></tr>
<tr><td>9</td><td>1 1 1 1 1</td></tr>
</tbody></table>
<br />
<br />
<div style="text-align: center;">
<span style="color: #cc0000;"><i><span style="font-size: small;">Table 2. 5 Bit Relay Output - Codes for Display Panel
</span></i></span></div>
<br />
<br />
These codes are placed in Channel 10. There are two possible
orientations.
<br />
<ol>
<li>For the right character of a pair, the MSB is placed
in bit 5; the LSB, in bit 1.</li>
<li>For the left character of a pair, the MSB is placed
in bit 10; the LSB, in bit 6.
</li>
</ol>
<br />
All the information necessary to operate the Display Panel
is transmitted from the computer through output channel 10
(OUT0). Two Display Panel characters are activated by OUT0
at a time.
<br />
<ul>
<li>Bits 1 - 5 (bit 1 is the low order bit) of OUT0
operate the right character of the selected pair;</li>
<li>Bits 6-10 operate the left character of the pair.</li>
<li>Bit 11 is used for special one-bit functions, such
as signs.</li>
<li>Bits 12-15 (bit 15 is the high order bit), which are
known as the Relayword code, select the appropriate
pair of Display Panel characters, See tables below.</li>
</ul>
<br />
<table align="center" bgcolor="yellow" border="1" cellpadding="10">
<tbody>
<tr><td><u>Bits 15-12</u></td><td><u>Bit 11</u></td><td><u>Bits 10-6</u></td><td><u>Bits 5-1</u></td></tr>
<tr><td>1 0 1 1</td><td>....</td><td>MD1</td><td>MD2</td></tr>
<tr><td>1 0 1 0</td><td>....</td><td>VD1</td><td>VD2</td></tr>
<tr><td>1 0 0 1</td><td>....</td><td>ND1</td><td>ND2</td></tr>
<tr><td>1 0 0 0</td><td>....</td><td>....</td><td>R1D1</td></tr>
<tr><td>0 1 1 1</td><td>+R1S</td><td>R1D2</td><td>R1D3</td></tr>
<tr><td>0 1 1 0</td><td>-RlS</td><td>R1D4</td><td>R1D5</td></tr>
<tr><td>0 1 0 1</td><td>+R2S</td><td>R2D1</td><td>R2D2</td></tr>
<tr><td>0 1 0 0</td><td>-R2S</td><td>R2D3</td><td>R2D4</td></tr>
<tr><td>0 0 1 1</td><td>....</td><td>R2D5</td><td>R3D1</td></tr>
<tr><td>0 0 1 0</td><td>+R3S</td><td>R3D2</td><td>R3D3</td></tr>
<tr><td>0 0 0 1</td><td>-R3S</td><td>R3D4</td><td>R3D5</td></tr>
</tbody></table>
<br />
<div style="text-align: center;">
<span style="color: #cc0000;"><i><span style="font-size: small;">Table 3. Relayword Format for OUTO
</span></i></span></div>
<br />
<br />
The Display Panel Output Buffer (DSPTAB) follows this same
format with respect to the low order 11 bits.
<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifsNCFQPT1BPjorvc_DmWHhBHvFubmKx26vPaq5I3x2XaMKvt8Dn7j_-w3KkHr3CRnqA3MUtz64lqDLgxy8ae3r8wfGwuqUgrr9Z3MX06GSuAiDn261F3fUKZUUVSXjd3Fg2jgmjumTADO/s1600/%2524T2eC16JHJHwE9n8igu5-BRUWel72%2529g%257E%257E60_57.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="257" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifsNCFQPT1BPjorvc_DmWHhBHvFubmKx26vPaq5I3x2XaMKvt8Dn7j_-w3KkHr3CRnqA3MUtz64lqDLgxy8ae3r8wfGwuqUgrr9Z3MX06GSuAiDn261F3fUKZUUVSXjd3Fg2jgmjumTADO/s400/%2524T2eC16JHJHwE9n8igu5-BRUWel72%2529g%257E%257E60_57.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 10. Inside DSKY. (Most likely a reproduction model.)</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<i><b>Timing.
</b></i><br />
<br />
The 15-bit word which activates a pair of characters in the
Display Panel is placed into OUT0 by DSPOUT, a program
operating in the Interrupt mode, DSPOUT is part of a larger
Interrupt program called T4RUPT. DSPOUT is activated
approximately once every 120 milliseconds. Thus, at maximum
activity, two numerical characters and a sign may be updated
on the Display Panel every 0.12 seconds.<span style="color: #274e13;"><i> [To update the whole display takes 11 x 0.12 sec = 1.32 sec in the worst case. See demonstration <a href="https://youtu.be/KwVbrIyJBw4" target="_blank">here</a>.]</i></span><br />
<br />
<br />
<br />
<i><b>Display Panel Buffer.</b></i>
<br />
<br />
DSPOUT obtains the 15-bit word to be placed in OUT0 from an
11-register buffer called DSPTAB. Each DSPTAB register
contains the information to activate a pair of numerical
characters (and perhaps a special single bit function, such
as sign) in the Display Panel. By retaining this
information, the DSPTAB reflects the present state of the
entire Display Panel. Thus it is possible to compare new
information with that already displayed and to place new
data in OUT0 only when they differ.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLGX4QJn5-pAZ2cRTEPgI1g3GSBKzfvlj6G_4Up0PP5oecWWFsk83iRAHuVuGsIfPdApndYmX58BU3MzblmIv8B_ahBVtXaJO61lpd73cE68n8CLxVphg8OujNaI3zhirV7yA8hw01xsuQ/s1600/14_lgc_dsky6.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="312" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLGX4QJn5-pAZ2cRTEPgI1g3GSBKzfvlj6G_4Up0PP5oecWWFsk83iRAHuVuGsIfPdApndYmX58BU3MzblmIv8B_ahBVtXaJO61lpd73cE68n8CLxVphg8OujNaI3zhirV7yA8hw01xsuQ/s400/14_lgc_dsky6.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 11. Signal levels from Grumman original paper.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<i><b>Other Indicators.</b></i><br />
<br />
<ul>
<li>The Key Release light is controlled by bit 5 of channel 11.</li>
<li>The Verb/Noun flash is controlled by bit 6 of channel 11.</li>
<li>The Operator Error Alarm light is controlled by bit 7 of
channel 11." </li>
</ul>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>DSKY Channels According to the Luminary 099 Program Listing (LM only) /2/</b></span><br />
<br />
<u><i>CHANNEL 10</i></u> - <span style="color: #4c1130;"><i><b>OUT0</b></i></span>: OUTPUT CHANNEL; REGISTER USED TO TRANSMIT LATCHING-RELAY DRIVING INFORMATION FOR THE DISPLAY SYSTEM. BITS 15-12 ARE SET TO THE ROW NUMBER (1-14 OCTAL) OF THE RELAY TO BE CHANGED AND BITS 11-1 CONTAIN THE REQUIRED SETTINGS FOR THE RELAYS IN THE ROW.<span style="color: #274e13;"><i> [Max update rate is about 8/sec or every 0.12 sec]</i></span><br />
<br />
<span style="color: #274e13;"><i>[Bits from table 3 above</i></span><br />
<br />
<ul>
<li><span style="color: #274e13;"><i>BIT 1 E</i></span></li>
<li><span style="color: #274e13;"><i>BIT 2 D</i></span></li>
<li><span style="color: #274e13;"><i>BIT 3 C -- Right 7-segment</i></span></li>
<li><span style="color: #274e13;"><i>BIT 4 B</i></span></li>
<li><span style="color: #274e13;"><i>BIT 5 A</i></span></li>
<li><span style="color: #274e13;"><i>BIT 6 E</i></span></li>
<li><span style="color: #274e13;"><i>BIT 7 D</i></span></li>
<li><span style="color: #274e13;"><i>BIT 8 C -- Left 7-segment</i></span></li>
<li><span style="color: #274e13;"><i>BIT 9 B</i></span></li>
<li><span style="color: #274e13;"><i>BIT 10 A</i></span></li>
<li><span style="color: #274e13;"><i>BIT 11 Sign</i></span></li>
<li><span style="color: #274e13;"><i>BIT 12 D</i></span></li>
<li><span style="color: #274e13;"><i>BIT 13 C -- Relayword code</i></span></li>
<li><span style="color: #274e13;"><i>BIT 14 B</i></span></li>
<li><span style="color: #274e13;"><i>BIT 15 A</i></span></li>
</ul>
<span style="color: #274e13;"><i> ]</i></span><br />
<br />
<br />
<u><i>CHANNEL 11</i></u> - <span style="color: #4c1130;"><i><b>DSALMOUT</b></i></span>: OUTPUT CHANNEL; REGISTER WHOSE BITS ARE USED FOR ENGINE ON-OFF CONTROL AND TO DRIVE INDIVIDUAL INDICATORS OF THE DISPLAY SYSTEM. BITS 1-7 ARE A RELAYS.<br />
<br />
<ul>
<li>BIT 1 ISS WARNING<span style="color: #274e13;"><i> [Inertial SubSystem warning from various sources]</i></span></li>
<li>BIT 2 LIGHT COMPUTER ACTIVITY LAMP</li>
<li>BIT 3 LIGHT UPLINK ACTIVITY LAMP</li>
<li>BIT 4 LIGHT TEMP CAUTION LAMP</li>
<li>BIT 5 LIGHT KEYBOARD RELEASE LAMP</li>
<li>BIT 6 FLASH VERB AND NOUN LAMPS</li>
<li>BIT 7 LIGHT OPERATOR ERROR LAMP</li>
<li>BIT 8 -- SPARE</li>
<li>BIT 9 TEST CONNECTOR OUTBIT</li>
<li>BIT 10 CAUTION RESET</li>
<li>BIT 11 -- SPARE</li>
<li>BIT 12 -- SPARE</li>
<li>BIT 13 ENGINE ON</li>
<li>BIT 14 ENGINE OFF</li>
<li>BIT 15 -- SPARE</li>
</ul>
<br />
<u><i>CHANNEL 15</i></u> - <span style="color: #4c1130;"><i><b>MNKEYIN</b></i></span>: INPUT CHANNEL; KEY CODE INPUT FROM KEYBOARD OF DSKY, SENSED BY PROGRAM WHEN PROGRAM <u><i>INTERRUPT #5</i></u> IS RECEIVED. USED BITS 5-1<br />
<br />
<span style="color: #274e13;"><i>[ Bits might be something like below</i></span><br />
<ul>
<li><span style="color: #274e13;"><i>Key code 1</i></span></li>
<li><span style="color: #274e13;"><i>Key code 2</i></span></li>
<li><span style="color: #274e13;"><i>Key code 3</i></span></li>
<li><span style="color: #274e13;"><i>Key code 4 </i></span></li>
<li><span style="color: #274e13;"><i>Key code 5</i></span></li>
<li><span style="color: #274e13;"><i>Proceed / Standby [moved to ch 032 later]</i></span></li>
<li><span style="color: #274e13;"><i>Keyboard reset</i></span></li>
<li><span style="color: #274e13;"><i>Caution light reset</i></span></li>
<li><span style="color: #274e13;"><i>-Spare-</i></span></li>
</ul>
<span style="color: #274e13;"><i>According to a Grumman schematic 1970.]</i></span><br />
<u><i></i></u><br />
<u><i><br /></i></u>
<u><i>CHANNEL 16</i></u> - <span style="color: #4c1130;"><i><b>NAVKEYIN</b></i></span>: INPUT CHANNEL; OPTICS MARK INFORMATION AND NAVIGATION PANEL DSKY (CM) OR THRUST CONTROL (LM) SENSED BY PROGRAM THEN PROGRAM <u><i>INTERRUPT #6</i></u> IS RECEIVED. USES BITS 3-7 ONLY.<br />
<br />
<ul>
<li>BIT 1 -- NOT ASSIGNED</li>
<li>BIT 2 -- NOT ASSIGNED</li>
<li>BIT 3 OPTICS X-AXIS MARK SIGNAL FOR ALIGN OPTICAL TSCOPE</li>
<li>BIT 4 OPTICS Y-AXIS MARK SIGNAL FOR AOT</li>
<li>BIT 5 OPTICS MARK REJECT SIGNAL</li>
<li>BIT 6 DESCENT+ ; CREW DESIRED SLOWING RATE OF DESCENT</li>
<li>BIT 7 DESCENT- ; CREW DESIRED SPEEDING UP RATE OF DESCENT</li>
</ul>
<span style="color: #274e13;"><i>[Bits 6 and 7 are most likely the ROD switch up / down momentary positions?]</i></span><br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>DSKY Interface Channels According to <i>VirtualAGC</i> Pages /3/</b></span><br />
<br />
Those pages have found the following relation for the various I/O bits, words and channels used. This reflects most likely the later phase of the Apollo Moon program (Luminary131 etc.).<br />
<br />
<u><i><b>AGC Output Channel 010</b></i></u><br />
<br />
Same as above.<br />
<br />
<u><i><b>AGC Output Channel 11</b></i></u><br />
<br />
<ul>
<li>...</li>
<li>BIT 2 Lights the "COMP ACTY" indicator.</li>
<li>BIT 3 Lights the "UPLINK ACTY" indicator</li>
<li>BIT 4 Lights the "TEMP" indicator.</li>
<li>BIT 5 Flashes the "KEY REL" indicator. (1.5 cycle-per-second rate.)</li>
<li>BIT 6 Flashes the VERB/NOUN display areas. (1.5 cycles per second. Duty cycle is about 1:3.)</li>
<li>BIT 7 Falshes the "OPR ERR" indicator. (1.5 cycle-per-second rate.)</li>
<li>...</li>
</ul>
<br />
<span style="color: #274e13;"><i>[From the original Luminary099 listing we can see (below) how the flashing of the verb and noun numbers was done simply by turning the above bit on. The AGC did not flash any bits itself so the flashing was done by the DSKY hardware alone.</i></span><br />
<br />
<span style="color: #274e13;">----
</span><br />
<span style="font-size: x-small;"><span style="color: #274e13;">
</span></span>
<pre><span style="font-size: x-small;"><span style="color: #274e13;">
FLASHON CAF BIT6 # TURN ON V/N FLASH
EXTEND # BIT 6 OF CHANNEL 11
WOR DSALMOUT
TC Q
FLASHOFF CS BIT6 # TURN OFF V/N FLASH
EXTEND
WAND DSALMOUT
TC Q
</span></span></pre>
<span style="font-size: x-small;"><span style="color: #274e13;">
</span></span>
<br />
<span style="color: #274e13;"><i>----]</i></span><br />
<br />
<br />
<u><i><b>AGC Output Channel 013</b></i></u><br />
<br />
<ul>
<li>... </li>
<li>BIT 10 Tests alarms and DSKY lights. (Drive ALL lamps ON to see if any is broken)</li>
<li>BIT 11 Lights the STANDBY indicator. (Might be incorrect info?) </li>
<li>... </li>
</ul>
<br />
<u><i><b>AGC Input Channel 015</b></i></u><br />
<br />
Same as above.<br />
<br />
<br />
<u><i><b>AGC Input Channel 032</b></i></u><br />
<br />
<ul>
<li>...</li>
<li>BIT 14 PRO (STBY) key pressed. (The logic is inverted)</li>
<li>.... </li>
</ul>
<br />
<span style="color: #274e13;"><i>[Worth to notice that the PROCEED button was considered so important that it was driven inverted and via channel 032 and had it own bit (not just one among the key codes as the other DSKY buttons)]</i></span><br />
<br />
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>LGC Interrupts /2/</b></span><br />
<br />
<table align="center" bgcolor="yellow" border="1" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;">
<tbody>
<tr><td><u>Vector Address Octal</u></td><td><u>Interrupt Name</u></td><td><u>Trigger Condition</u></td><td><u>Description</u></td></tr>
<tr><td>4000</td><td>Startup</td><td>AGC power ON</td><td>Starting address after AGC power up</td></tr>
<tr><td>4004</td><td>T6RUPT</td><td>TIME6 decrement to 0</td><td>Timer for RCS jets, used by the Digital Autopilot (DAP)</td></tr>
<tr><td>4010</td><td>T5RUPT</td><td>TIME5 timer overflow </td><td>DAP timer</td></tr>
<tr><td>4014</td><td>T3RUPT</td><td>TIME3 timer overflow </td><td>WAITLIST task scheduler</td></tr>
<tr><td>4020</td><td>T4RUPT</td><td>TIME4 timer overflow </td><td>DSKY monitoring and updating</td></tr>
<tr><td>4024</td><td>KEYRUPT1</td><td>Keystroke from DSKY</td><td>Keycode from DSKY is available in channel 15</td></tr>
<tr><td>4030</td><td>KEYRUPT2</td><td>Keystroke from 2nd DSKY</td><td>Keycode from Navigation DSKY is available in channel 16 (CM only)</td></tr>
<tr><td>4034</td><td>UPRUPT</td><td>Data ready in INLINK register</td><td>Used for DSKY uplinks (remote control etc.)</td></tr>
<tr><td>4040</td><td>DOWNRUPT</td><td>Downlink register ready for more data</td><td>AGC downlink telemetry (to MCC consoles etc.)</td></tr>
<tr><td>4044</td><td>RADARUPT</td><td>Data in RNRAD register is ready</td><td>Data from rendezvous radar</td></tr>
<tr><td>4050</td><td>RUPT10</td><td>Used only by lunar landing guidance</td><td>LM P64 redesignation</td></tr>
</tbody></table>
<br />
<br />
<br />
<br />
<br />
<h4>
RESOURCES
</h4>
<ul>
<li>/1/ Green, Alan I., and Filene, Robert J.; MIT
Instrumentation Laboratory - Apollo Guidance,
Navigation and Control - E-2129 - KEYBOARD AND
DISPLAY PROGRAM AND OPERATION - DSR Project
55-23850, MSC NASA Contract NAS 9-4065</li>
<li>/2/ Luminary 1A version 099 listing.</li>
<li>/3/ <a href="http://www.ibiblio.org/apollo/index.html" target="_blank">VirtualAGC</a> </li>
</ul>
<br />
<div style="text-align: center;">
* * *
</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-18086720321869680142016-12-22T18:43:00.001+00:002016-12-26T23:24:42.068+00:00LM Descent to the Moon - Part 6 - Programming (1971) (Apollo Lunar-Descent Guidance, 1971)
<br />
<br />
<i><span style="color: #274e13;">[The following MIT / NASA's 1971 text, partial reprint of the reference /0/,
describes the descent algorithms used in the Apollo Lunar Module computer program (Luminary version 099/1A, about
63,000 lines of <a href="https://archive.org/details/yulsystemsourcec00hugh" target="_blank">YUL assembly</a> code) and flown summer
1969. This paper actually describes an advanced version of the algorithm which was not used since the older version which was more tested at that time (1969) was good enough for the job. What so ever, the text gives a good glance to the manned planetary descent programming.]
</span></i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCHQibDbxBuxADGmO8hmPTX0OU5BWhZIV6d6nezsJ3Qzmjt5Qen1bb8NVkb6CoaNCfBx7ssY_smP7JPfp1y9Dyhq_bSgoA2F7_80X15LE9PpcHlWVyfT4SSE2XqIW-r67fy6WypwEsLldt/s1600/Fig_1_Piloting_LM.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="310" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCHQibDbxBuxADGmO8hmPTX0OU5BWhZIV6d6nezsJ3Qzmjt5Qen1bb8NVkb6CoaNCfBx7ssY_smP7JPfp1y9Dyhq_bSgoA2F7_80X15LE9PpcHlWVyfT4SSE2XqIW-r67fy6WypwEsLldt/s400/Fig_1_Piloting_LM.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. Components of the Lunar-Descent Guidance System.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<a name='more'></a><h4>
APOLLO LUNAR-DESCENT GUIDANCE /0/
</h4>
<br />
"Lunar-descent guidance begins with the lunar module (LM) at
about 15-km altitude in a slightly elliptical coasting lunar
orbit, and ends with the LM on the lunar surface.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3dICOuBKMLzucc5NOFsJ5frwIB7YiNEBy9HD7uQWa3DOlPhhqLE2v1Zvw-cAva7lOEg32GwvHUIbQAIJ_6LegpPBwgsrp-DYWteyhWV9X9r-IuYsB_4NqQj_jQ2Gao1YwbwCYvY1dlwGi/s1600/houstonMCC.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="380" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3dICOuBKMLzucc5NOFsJ5frwIB7YiNEBy9HD7uQWa3DOlPhhqLE2v1Zvw-cAva7lOEg32GwvHUIbQAIJ_6LegpPBwgsrp-DYWteyhWV9X9r-IuYsB_4NqQj_jQ2Gao1YwbwCYvY1dlwGi/s400/houstonMCC.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 56. MCC (Mission Control Center) in MSC (Manned Spacecraft Center, currently JSC, Johnson Space Center), Houston, Texas contained everything that was needed to control the flight of the Apollo spacecrafts during active missions, includeing the Real Time Computer Complex (RTCC) with IBM and other computers and human flight controllers in the MOCR (Mission Operations Control Room).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The
guidance is performed by the onboard LM guidance computer
(LGC), which takes input data and commands directly from the
LM crew and via the uplink from NASA's Real Time Computation
Center (RTCC) in Houston, Texas.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs3LYDKovIqGKpLygeLosXiinurS6ghxdnF_u1FiMc_fXlUF-i_JF7C6gTz9AEai8Vt2pQSkGnoKdldGBcqqATJdcpwV1z_G2jzTRcIW8_vUKz0FJaVsnkX7rlgJ8vWNVPoN5A7EBFQvsg/s1600/Figure_3_RTCC.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgs3LYDKovIqGKpLygeLosXiinurS6ghxdnF_u1FiMc_fXlUF-i_JF7C6gTz9AEai8Vt2pQSkGnoKdldGBcqqATJdcpwV1z_G2jzTRcIW8_vUKz0FJaVsnkX7rlgJ8vWNVPoN5A7EBFQvsg/s400/Figure_3_RTCC.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 57. Apollo Real Time Computer Complex inside MCC (Mission Control Center) Houston, Texas, showing IBM 7094 computer, year about 1966</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The crew consists of a
commander and a LM pilot. (See Figure 1.) Standing on the
left, the commander monitors and controls the descent using
visual cues and various hand controllers and switches.
Standing on the right, the LM pilot monitors the computer
display, vocally relays pertinent data to the commander, and
enters any necessary data into the computer via the
keyboard.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLem5RSzR_-2wTivTJOMBa80QutbYlpB7RSW4BudAffLh7UQA_1lpA97OEocqMqbTL5HqMCREoR8R9v-RXLY6va-t7Zp24bg22Cua_xm4aockzgGPhofOSiyPor73v_Imn1oIWr3xX6605/s1600/LM_PGNCS.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="226" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLem5RSzR_-2wTivTJOMBa80QutbYlpB7RSW4BudAffLh7UQA_1lpA97OEocqMqbTL5HqMCREoR8R9v-RXLY6va-t7Zp24bg22Cua_xm4aockzgGPhofOSiyPor73v_Imn1oIWr3xX6605/s400/LM_PGNCS.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 58. LM PGN(C)S Installation and Related Systems.</span></i></span></td></tr>
</tbody></table>
<br />
The primary guidance mode for the lunar descent is
automatic; the LGC (LM Gudance Computer, see figure 58.) controls both attitude and thrust. The
commander can, temporarily or permanently, select
nonautomatic guidance modes if he wishes to control,
manually, attitude or thrust or both. The nonautomatic
modes, not described further in this report, provide
attitude and thrust references for the commander to follow
if he chooses to fly the LM manually along the automatic
guidance profile.
<br />
<br />
This report describes how the Apollo lunar-descent guidance
works, why it was designed this way, and, in several cases,
how it might have been designed differently. The concepts
described can be applied to landing on any planetary body,
with or without atmosphere, should man resolve to continue
this adventure. The solutions presented offer ample
opportunity for checking the theory. Such checks have been
made, and all algorithms are known to work as conceived."
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5aAPAAL9wkJn37TAO8ALvNHpknIm_sS52Z57vhIVWoQCZmkHSxyDgDgll9vi6fldO9ABsuNXfuqHriLGA3rMzn0__Jw-8gmUeuHJZU_kfzq4HJpdoOoR3C6tepjHpxSQbhjDRULlpx-sP/s1600/Fig_2_Lunar_descent_guidance_phases_and_targets.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="243" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5aAPAAL9wkJn37TAO8ALvNHpknIm_sS52Z57vhIVWoQCZmkHSxyDgDgll9vi6fldO9ABsuNXfuqHriLGA3rMzn0__Jw-8gmUeuHJZU_kfzq4HJpdoOoR3C6tepjHpxSQbhjDRULlpx-sP/s400/Fig_2_Lunar_descent_guidance_phases_and_targets.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 2. Lunar-descent-guidance Phases and Targets</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #073763;"><b>Descent Phases
</b></span><br />
<br />
"The lunar descent is a nominally-planar trajectory
consisting of three phases illustrated in Figure 2 and
described as follows:
<br />
<ol>
<li> <b><u><i>The braking phase (Program 63, or <span style="color: magenta;">P63</span>)</i></u></b> is initiated by
keyboard entry about 10 minutes before nominal ignition
time. P63 first computes the precise time and attitude for
ignition. Next, at typically 492-km slant-range from the
landing site, P63 ignites the DPS. Finally, P63 transfers
the LM to the terminal state required as initial conditions
for the succeeding approach phase. The transfer takes
typically 514 seconds and is near-optimal.</li>
<li> <u><i><b>Approach-phase (<span style="color: magenta;"><span style="background-color: white;">P64</span></span>) guidance</b></i></u> begins with initial
conditions consisting of, typically a) 2.2-km altitude and 7.5-km ground range and b) -44-m/sec vertical velocity and 129-m/sec forward
velocity. In typically 146 seconds, P64 transfers the LM to a point
almost directly above the landing site. P64 provides
continuous visibility of the lunar surface and,
specifically, of the landing site until around 5 seconds
before terminus. During P64 the commander can direct the LGC
to land at any visually chosen point on the lunar surface by
a landing-site redesignation procedure which can be
continued until initiation of the terminal-descent phase.</li>
<li> <u><i><b>The terminal-descent phase (<span style="color: magenta;">P66</span>)</b></i></u> begins automatically at
typically 30-m altitude and 11-m ground range from the
landing site, or it may be initiated by the commander any
time during P64. The P66 guidance algorithm controls
velocity only; there is no position control. P66 nulls the
forward and lateral velocity components to produce a
vertical approach to the lunar surface, an objective which
cannot be achieved from visual cues when the surface is
obscured by a sheet of radially moving dust. P66 controls
altitude rate to a reference value that is incremented or
decremented by 0.3-m/sec each time the commander raises or
lowers a three-position <u>rate-of-descent (ROD) control switch</u>
located near his left hand."
</li>
</ol>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidR-oXtbNkFpF6jE_7pJfmflRBMOG7YfyoHVJB1Q-d3Yog-oicfepral42L2J45ze5ufKyyqjSfTTRYCiA_5hLNHQ0ElHm-xHE-e8-J4cJanjt1HJIjAS_2TEl-MKc-M2fE95GP-iUUcMQ/s1600/Lunar_Module_Landing_Controls.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidR-oXtbNkFpF6jE_7pJfmflRBMOG7YfyoHVJB1Q-d3Yog-oicfepral42L2J45ze5ufKyyqjSfTTRYCiA_5hLNHQ0ElHm-xHE-e8-J4cJanjt1HJIjAS_2TEl-MKc-M2fE95GP-iUUcMQ/s400/Lunar_Module_Landing_Controls.png" width="330" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 59. Lunar Module Landing Controls inside LM cockpit. Most notably the ROD control switch and ACA next to DSKY (LGC Display and Keyboard unit).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #0c343d;"><b>Navigation, Guidance, and Control Configuration
</b></span><br />
<br />
"The Navigation, Guidance, and Control configuration
illustrated in Figure 3 applies to all LM powered-flight
guidance maneuvers. This report describes only the yellow blocks of Figure 3. All routines are processed once every
two seconds, except the vertical channel of the P66 guidance
algorithm is processed once per second, and the digital auto
pilot is processed 10 times per second.
<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsZ3a4W64WCVQRFORfR8SmR_5fQIQghc8NzCr6bAGB7nBts7e9uc6A7NkqZ8rG9zCnQQT33GFJ-ABm4IjTrlfIbRFi3BAp3gR3ZzXDGFQ3OJpk8M8oZHPUSJqDlNvDbCq6utJkA3Of4aT9/s1600/Fig_3_Main_routine.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgsZ3a4W64WCVQRFORfR8SmR_5fQIQghc8NzCr6bAGB7nBts7e9uc6A7NkqZ8rG9zCnQQT33GFJ-ABm4IjTrlfIbRFi3BAp3gR3ZzXDGFQ3OJpk8M8oZHPUSJqDlNvDbCq6utJkA3Of4aT9/s400/Fig_3_Main_routine.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. Navigation, Guidance, and Control Configuration.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<u><i><b>Navigation.</b></i></u> Navigation (see Kriegsman /1/) provides an estimate of the
current state vector based on data from an inertial
measurement unit (IMU) and a landing radar. IMU data are
used throughout all thrusting maneuvers, but, to avoid
accumulation of inertial errors, IMU data are not used
during coasting flight except for a minimum period
immediately preceding and following each thrusting maneuver.
The landing radar provides altitude data below typically
10-km altitude, and velocity data below 610-m/sec.<br />
<br />
<u><i><b>Guidance. </b></i></u>Guidance transfers the LM from the current state to the
terminus of the current phase. In addition to the current
state estimate from Navigation, Guidance is based on
precomputed targets from the ground-based targeting program.
The outputs from the Guidance algorithm are a unit thrust
command and a unit window command issued to the
Powered-flight Attitude-maneuver Routine, and a
thrust-acceleration command issued to the Throttle Routine.
Through these routines, Guidance controls the thrust vector
magnitude and direction with respect to inertial space.
<br />
<br />
<u><i><b>Powered-flight Attitude-maneuver Routine.</b></i></u> The Powered-flight Attitude-maneuver Routine (ATT) connects
all guidance programs, descent and ascent, to the digital
auto pilot (DAP). ATT inputs are two command vectors; a unit
thrust command and a unit window command. ATT estimates a
unit thrust vector from accelerometer measurements, and
issues incremental commands to the DAP. These commands cause
the DAP to drive the estimated unit thrust vector into
coincidence with the unit thrust command and the symmetry
plane of the LM into coincidence with the unit window
command.
<br />
<br />
During P64, as long as the landing site would be visible,
the unit window command issued to ATT by Guidance is the
line-of-sight vector to the current landing site. By
rotating the LM symmetry plane into coincidence with the
line-of-sight vector, ATT superimposes the landing-point
designator reticles of Figure 1 on the current landing
site."
<br />
<br />
<u><i><b>Throttle Routine.</b></i></u> The Throttle Routine (THROT) connects several
powered-flight guidance programs to the DPS. The DPS is used
by all descent guidance programs, one of the two abort
programs, and one guidance program whose purpose is to
provide a velocity-vector increment computed by the Real
Time Computation Center in Houston and transmitted to the
LM.
<br />
<br />
The DPS must be operated either at the maximum-thrust point
(about 92% of the rated thrust of 46,706 newtons) or within
a permitted-thrust region (11 to 65% of rated thrust). The
intervening region (65 to 93%) is forbidden because in this
region oxidizer flow and fuel flow make independent
transitions from cavitating to non cavitating regimes. The
independent transitions cause gross deviations from the
required mixture ratio and produce excessive erosion of the
DPS nozzle.
<br />
<br />
Using a computed mass estimate, a thrust-acceleration
measurement, and the thrust-acceleration command from the
guidance equations, THROT computes the current and commanded
thrusts and issues thrust increment commands to the DPS.
These commands either
<br />
<ol>
<li> drive the computed thrust into coincidence with
the commanded thrust whenever the commanded thrust
lies within the permitted thrust region,</li>
<li> produce maximum thrust whenever the commanded
thrust lies above the permitted-thrust region, or</li>
<li> produce minimum thrust whenever the commanded
thrust lies below the permitted-thrust region.
</li>
</ol>
<br />
<u><i><b>Braking-phase and Approach-phase Targeting Program. </b></i></u>The targeting program provides targets for P63 and P64. The
targets define braking- and approach-phase reference
trajectories as independent vector polynomials centered at
individual target points as illustrated in Figure 2.
Although only P63 and P64 are targeted, the targets are
designed to achieve all the guidance objectives of P63, P64,
and P66.
<br />
<br />
<u><i><b>Digital Auto pilot. </b></i></u>The DAP (see Widnall /2/) controls the attitude of the LM
during powered flight by means of control effectors
consisting of a reaction control system and a trim gimbal
system. As the name implies, the trim gimbal system is a
slow system used primarily for trimming the DPS thrust
vector through the LM center of mass."
<br />
<br />
<br />
<h4>
DEFINITIONS OF LUNAR DESCENT COORDINATE FRAMES,
ATTITUDE ANGLES, AND GIMBAL ANGLES
</h4>
<br />
"Three coordinate frames are required for lunar descent
guidance because
<br />
<br />
<ol>
<li>(P) all inertial measurements are with respect to the
stable platform of the IMU,</li>
<li>(G) P63 and P64 guidance is with respect to a landing
site which rotates with, and can be redesignated
along, the lunar surface, and</li>
<li>(B) thrust-vector determination and landing-site
redesignations are with respect to LM body axes."
</li>
</ol>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikm4ThWBfu9ar3sU8BIZcavuHU0DpRGW61F0urnIgg47WbMqdF42x7104-b_Uv2xKGbwfslugTpUJZuNiHg2q7C5_BE683YmtbIvDEl7Dqo6vviVdYCiaqsvWUrDuS9egTbLgK1aPiQvhn/s1600/Fig_4_Coordinates.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="380" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikm4ThWBfu9ar3sU8BIZcavuHU0DpRGW61F0urnIgg47WbMqdF42x7104-b_Uv2xKGbwfslugTpUJZuNiHg2q7C5_BE683YmtbIvDEl7Dqo6vviVdYCiaqsvWUrDuS9egTbLgK1aPiQvhn/s400/Fig_4_Coordinates.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 4. Lunar-descent Coordinate Frames.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
These coordinate systems are illustrated in Figure 4 and
defined as follows:<br />
<ol>
<li><b><i>Platform coordinates.</i></b> Variables in platform
coordinates are tagged P. The origin is at the
center of the moon, the XP-axis pierces the nominal
(unredesignated) landing site at the nominal landing
time, the ZP-axis is parallel to the orbital plane
of the Command Module* and points forward, and the
YP-axis completes the right-hand triad. Platform
coordinates are nonrotating. <span style="color: #274e13;"><i>[*The LGC transfers state vectors in platform
coordinates to an abort guidance system (AGS). The
AGS requires the state to be expressed in a frame
whose Z axis parallels the orbital plane of the
command module.] </i></span></li>
<li><i><b>Guidance coordinates.</b></i> Variables in guidance
coordinates are tagged G. The origin coincides
continuously with the current landing site (the
frame rotates with the moon); the XG-axis is
vertical; the ZG-axis lies in, or near, the plane
containing the LM and the landing site and points
forward; and the YG-axis completes the right-hand
triad. Thus, the origin and orientation of the
guidance frame are altered each time the landing
site is redesignated. Guidance-frame <a href="https://en.wikipedia.org/wiki/Unit_vector" target="_blank">unit vectors</a>
expressed in platform coordinates are the row
vectors <span style="color: blue;"><i>C_GPx</i></span>, <span style="color: blue;"><i>C_GPy</i></span>, <span style="color: blue;"><i>C_GPz</i></span> of the matrix <span style="color: blue;"><i>CGP</i></span>.</li>
<li><i><b>Body coordinates.</b></i> Variables in body coordinates
are tagged B. These are the generally accepted LM
coordinates. The XB-axis is in the direction of the
nominal thrust vector (up), the ZB-axis is directed
forward (during the final), and the YB-axis completes the right-hand
triad. Body-frame unit vectors expressed in platform
coordinates are the row vectors <span style="color: blue;"><i>C_BPx</i></span>, <span style="color: blue;"><i>C_BPy</i></span>, <span style="color: blue;"><i>C_BPz</i></span>
of the matrix <span style="color: blue;"><i>CBP</i></span> (underscore is used to mark a vector, see "Nomenclature" at the end of this paper for details). <span style="color: #274e13;"><i>[Notice that this is NOT the normal airplane body axis convention which is: x forward, z down, and y right.]</i></span>
</li>
</ol>
<br />
From these definitions it is noted that <u>if the LM lands at
the nominal site at the nominal time in a nominal erect
attitude, the three frames will be parallel at the instant
of touchdown</u>.
<br />
<br />
The following conventions are defined for orthogonal
matrices:
<br />
<ol>
<li>A matrix element is denoted by two subscripts
which indicate the row and column respectively of
the element. Thus <span style="color: blue;"><i>CBPXy</i></span> denotes the Y-component of
the row vector <span style="color: blue;"><i>C_BPx</i></span>.</li>
<li>A matrix transpose (inverse) is denoted by
interchanging tags.</li>
<li>From the definitions, it follows that matrix
products are obtained by deleting internal tags."
</li>
</ol>
<br />
By conventions 2 and 3, a vector <span style="color: blue;"><i>V_</i></span> is transformed to body
from guidance coordinates by
<br />
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-D2uu8pC1a42M0s1ZOUEQeCE5esirNK-UsZLt7THuuuqrTvRJNJI5WhgIepL8cdbB039U2BGpPIiDvIVKc0x0lhooJlpiiMqwrl6bq4x-nKbIXfzIw-NZfLuU9xsTT3di372EZKhMqfk5/s1600/eq_58.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="120" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-D2uu8pC1a42M0s1ZOUEQeCE5esirNK-UsZLt7THuuuqrTvRJNJI5WhgIepL8cdbB039U2BGpPIiDvIVKc0x0lhooJlpiiMqwrl6bq4x-nKbIXfzIw-NZfLuU9xsTT3di372EZKhMqfk5/s320/eq_58.png" width="320" /></a></div>
<br />
<br />
LM attitude angles are a set of Euler angles defined as
clockwise rotations about the XB-axis (yaw), the displaced
YB-axis (pitch), and the displaced ZB-axis (roll).
<br />
<br />
LM gimbal angles are a set of Euler angles defined as
clockwise rotations about the YB-axis (inner), the displaced
ZB-axis (middle), and the displaced XB-axis (outer)."
<br />
<br />
<br />
<br />
<h4>
</h4>
<h4>
BRAIKING-PHASE AND APPROACH-PHASE GUIDANCE
</h4>
<br />
"The guidance programs for P63 and P64 are almost identical.
The two phases use the same guidance algorithm, the same
Throttle Routine, and the same Powered flight
Attitude-maneuver Routine. The differences are<br />
<ol>
<li>the guidance equation selects different sets of
targets,</li>
<li>the erection of the guidance coordinate frame is
slightly different, and</li>
<li>landing site redesignation capability is
available only in P64."
</li>
</ol>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Guidance Equation Derivation
</b></span><br />
<br />
"To guide a spacecraft from any initial or current state to
a specified target state can be viewed either as an explicit
guidance problem or as an implicit guidance problem.
Explicitly, we can repetitively determine, as the mission
progresses, a vector polynomial function of time that
intersects the current and target states. Guidance then
commands the corresponding profile of acceleration vs time.
Implicitly, we can define, in advance of the mission, a
reference trajectory as a vector polynomial function of time
that evolves backward from the target state but cannot be
expected to intersect a dispersed initial (or dispersed
current) state. Onboard guidance then commands an
acceleration vector profile composed of three terms, namely
the acceleration along the reference trajectory minus two
feedback terms proportional to the deviations in velocity
and position of the actual trajectory with respect to the
reference trajectory. In either the explicit or the implicit
case, repetitively solving the guidance problem produces
convergence upon the specified target state even though the
target point may be redesignated in flight and the commanded
acceleration is not precisely achieved because of control
errors.
<br />
<br />
The implicit guidance equation derived here is
categorically superior to the explicit guidance equation
because the explicit equation is merely a special case, as
will be shown. Besides being intellectually more satisfying,
the implicit equation has demonstrated in simulations
significantly faster reduction of deviations from the
reference trajectory. Deviations come from navigation errors
and from displacing the reference trajectory to intersect a
redesignated landing site. Rapid reduction of deviations
restores a nominal approach to the redesignated landing
site. <u>Unfortunately, the implicit equation had not been
developed when the program for Apollo 11 was coded, and the
advantages were insufficient to recode the guidance program
for later missions.
</u><br />
<br />
<u><i>Cherry</i></u> (/3/) derived the explicit guidance equation. <u><i>Klumpp</i></u>
(/4/, /5/) simplified it for LGC coding and generalized it
to nth order. <u><i>Moore et al</i></u> (/6/) derived an implicit equation
which did not generalize the explicit equation. <u>The general
implicit guidance equation is now derived and specialized to
the explicit case.
</u><br />
<br />
It is convenient to think of the reference trajectory as
evolving backwards in time from the target point, with the
time variable T reaching zero at the target point and
negative prior to that point. Thus target-referenced time
(T) is to be distinguished from clock-time (t). Because
guidance gains would become unbounded, the target point is
never reached. Instead, a guided phase is terminated at a
negative time T and the succeeding phase is started. Both
the terminus and the target point lie on the reference
trajectory, but the target point lies beyond the portion
that is actually flown, similar to a suggestion of McSwain
and Moore.(/7/)
<br />
<br />
In terms of a vector polynomial function of
target-referenced time, we wish to define a reference
trajectory that satisfies a two-point boundary value problem
with a total of five degrees of freedom for each of the
three components. This number of degrees of freedom is
required in order to constrain terminal thrust in P63 and to
shape the trajectory design in P64, as is discussed in
connection with the targeting program.
<br />
<br />
A quartic polynomial is the minimum order with which five
constraints on the reference trajectory can be satisfied.
With the reference trajectory evolving backwards in time
from the target point, it can be defined as
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvYoCKMHEbEvXcbB_xHzF8bFG4KxefZmYV1tjZ_J8L5wiSGJpKlk3asNuYO6VQazu-yHJEbBKjHQ3PSzosj8tYS8h2T3stLwFhGd6tNR3lbFYpudKGP7ZsZtU-kKbf9l8nvnr1o_l5VVij/s1600/eq_01.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="48" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvYoCKMHEbEvXcbB_xHzF8bFG4KxefZmYV1tjZ_J8L5wiSGJpKlk3asNuYO6VQazu-yHJEbBKjHQ3PSzosj8tYS8h2T3stLwFhGd6tNR3lbFYpudKGP7ZsZtU-kKbf9l8nvnr1o_l5VVij/s320/eq_01.png" width="320" /></a></div>
<br />
<br />
where R_RG is the position vector on the reference
trajectory in guidance coordinates at the negative time <span style="color: blue;"><i>T</i></span>,
and <span style="color: blue;"><i>R_TG</i></span>, <span style="color: blue;"><i>V_TG</i></span>, <span style="color: blue;"><i>A_TG</i></span>, <span style="color: blue;"><i>J_TG</i></span>, and <span style="color: blue;"><i>S_TG</i></span> are the target
position, velocity, acceleration, jerk, and snap.
<br />
<br />
The acceleration to be commanded at any point in space
consists of three terms: the acceleration of the reference
trajectory at the particular time T, minus two feedback
terms proportional to velocity and position deviations from
the reference trajectory. Taking derivatives of Eq. (1) as
the velocity and acceleration on the reference trajectory
yields the three-term guidance equation
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrXBtZ5zGmXk1wO-vvWNiZkTmvL_5ZvsThszOB3jXF98-FDbzp2NoKqpyzHuQ-yYVnRSuwWW3cXZFw_zlusV9EBmV855Nc1xNFHOp7W8McWo6LxOhpP52DpDqByq_oZ3rWPuE-slXwpnIm/s1600/eq_02.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="55" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrXBtZ5zGmXk1wO-vvWNiZkTmvL_5ZvsThszOB3jXF98-FDbzp2NoKqpyzHuQ-yYVnRSuwWW3cXZFw_zlusV9EBmV855Nc1xNFHOp7W8McWo6LxOhpP52DpDqByq_oZ3rWPuE-slXwpnIm/s400/eq_02.png" width="400" /></a></div>
<br />
<br />
where <span style="color: blue;"><i>A_CG</i></span> is the commanded acceleration (vector), <span style="color: blue;"><i>V_G</i></span> and <span style="color: blue;"><i>R_G</i></span> are
the current velocity and position (vectors), and <span style="color: blue;"><i>KV</i></span> and <span style="color: blue;"><i>KR</i></span> are the
nondimensional feedback gains.
<br />
<br />
Combining like terms in Eq. (2) yields<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4mfNbr_3ESb-LfuJkWd4npSFdXsV4KcGFxgOHLTO1ZjEHhGU_vCciQGfO9cb2u3RBh7iQfT73HztFOQZokh_T3F_kH3Okbtq2e6BVlTLMJ6o5zTqAeabHW6l7jJYGCavzPAQhFpFM6Ruc/s1600/eq_03.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="169" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj4mfNbr_3ESb-LfuJkWd4npSFdXsV4KcGFxgOHLTO1ZjEHhGU_vCciQGfO9cb2u3RBh7iQfT73HztFOQZokh_T3F_kH3Okbtq2e6BVlTLMJ6o5zTqAeabHW6l7jJYGCavzPAQhFpFM6Ruc/s320/eq_03.png" width="320" /></a></div>
<br />
Equation (3) is the implicit guidance equation. Although the
reference trajectory is quartic, the trajectory generated by
the implicit guidance equation is obviously not. The
implicit equation can, however, be specialized to the
explicit equation - which does generate a quartic - by a
specific choice of the feedback gains <span style="color: blue;"><i>KV</i></span> and <span style="color: blue;"><i>KR</i></span>. First we
note that Eq. (2) may be identified with the linear
second-order differential equation
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9pjlS_Ws3UQbQFCmAFjVoHq77jb4sIKuPyb32bijO8l0QAk7kDPc3-sT7Qt2wLOdXNTscMSZPyTwcXofi-8AOeCDI8IaOVpvHXBtVadOV88qx3bsHo3tz4qs6PLIiAKkuUKSKOIgkSoRz/s1600/eq_59.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="25" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj9pjlS_Ws3UQbQFCmAFjVoHq77jb4sIKuPyb32bijO8l0QAk7kDPc3-sT7Qt2wLOdXNTscMSZPyTwcXofi-8AOeCDI8IaOVpvHXBtVadOV88qx3bsHo3tz4qs6PLIiAKkuUKSKOIgkSoRz/s320/eq_59.png" width="320" /></a></div>
<br />
<br />
by the associations (noting <span style="color: blue;"><i>T</i></span> is negative)
<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAOgqKjUtZUv27ge6I9_nDroKvCAP8m4O8TkPmRwsO9Wip34cj1eFvUwGgDquesRkBEphBXacnbOaRgOB_tvaN8Y9or5NFFtxo5yi9SdIDtQe8NjAu1vA48d01LnwVzJFTyypBhp-1VB4a/s1600/eq_04.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="72" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAOgqKjUtZUv27ge6I9_nDroKvCAP8m4O8TkPmRwsO9Wip34cj1eFvUwGgDquesRkBEphBXacnbOaRgOB_tvaN8Y9or5NFFtxo5yi9SdIDtQe8NjAu1vA48d01LnwVzJFTyypBhp-1VB4a/s320/eq_04.png" width="320" /></a></div>
<br />
<br />
where omega_n is the <a href="https://en.wikipedia.org/wiki/Vibration#Damped_and_undamped_natural_frequencies" target="_blank">undamped natural frequency</a> and zeta is
the <a href="https://en.wikipedia.org/wiki/Damping_ratio" target="_blank">damping ratio</a>. Of course the system is time varying.
However, this association does afford some intuition on gain
setting. Solving Eqs. (4) yields <br />
<br />
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<br />
<br />
where <span style="color: blue;"><i>P</i></span> is the undamped period (2 <span style="color: blue;"><i>pi</i></span>/<span style="color: blue;"><i>omega_n</i></span>), and
<br />
<br />
<br />
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<br />
Equation (5) provides a means of controlling the system
response time in terms of the nondimensional ratio <span style="color: blue;"><i>P/T</i></span>, and
Eq. (6) provides a means of setting the damping ratio.
<br />
<br />
An interesting set of values to choose for response and
damping is
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
This choice yields
<br />
<br />
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<br />
<br />
When these values are substituted into Eq. (3), the result
is the explicit guidance equation derived in references /3/ to
/5/,<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
The discussion of implicit vs explicit guidance is concluded
by introducing the concept of a space containing all
permissible combinations of guidance parameters. Implicit
guidance-parameter space is one quadrant of the <span style="color: blue;"><i>zeta</i></span>, <span style="color: blue;"><i>P/T</i></span>
plane or, equivalently, one quadrant of the <span style="color: blue;"><i>KR</i></span>, <span style="color: blue;"><i>KV</i></span> plane.
Explicit guidance-parameter space is a single point in
either plane.
<br />
<br />
Equation (7) presents the explicit guidance equation
assuming negligible transport time delay. The explicit
equation programmed in Apollo is corrected to command an
acceleration appropriate for the time at which the
acceleration is predicted to be achieved. Let this predicted
target-referenced time be
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
where <span style="color: blue;"><i>LEADTIME</i></span> is the transport delay due to computation and
command execution. An explicit guidance equation will now be
derived that fits a quartic polynomial through the target
position, velocity, and acceleration, and through the
current position and velocity. The acceleration of the
quartic at the predicted time <span style="color: blue;"><i>Tp</i></span> is the acceleration to
command at the current time <span style="color: blue;"><i>T</i></span> in order to realize the
quartic profile. It will be shown that the resulting
guidance equation reduces to Eq. (7) for <span style="color: blue;"><i>Tp = T</i></span>, and
therefore Eq. (7) generates a quartic profile when the
transport delay is zero.
<br />
<br />
Constraining the actual trajectory to be a quartic function
of time allows the current position and velocity to be
expressed as
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
where <span style="color: blue;"><i>J_TGA</i></span> and <span style="color: blue;"><i>S_TGA</i></span> are the jerk and snap vectors which would be
achieved at the target point, and are not targets loaded
into LGC memory. Solving Eq. (8) for the jerk and snap
yields
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
The acceleration to be commanded at the current time <span style="color: blue;"><i>T</i></span> and
realized at the predicted time <span style="color: blue;"><i>Tp</i></span> is
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
Substituting Eq. (9) into Eq. (10) and simplifying yields
the Apollo lunar-descent guidance equation
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
<br />
Note that when time <span style="color: blue;"><i>T</i></span> is large in magnitude compared to the
transport delay, <span style="color: blue;"><i>Tp/T</i></span> approaches unity, all bracketed
coefficients in Eq. (11) approach unity, and Eq. (11)
approaches Eq. (7) identically. The net effect of Eq. (11)
not achieved by Eq. (7) is a gain reduction as the target
point is approached. Because Eqs. (7) and (11) are identical
for <span style="color: blue;"><i>Tp=T</i></span>, Eq. (7) generates a quartic profile when the
transport delay is zero.
<br />
<br />
In the derivation of the guidance Eq. (7) or (11), nothing
constrained the time <span style="color: blue;"><i>T</i></span>. At any point in a guided phase, <span style="color: blue;"><i>T</i></span>
could be set to any arbitrary negative value, and Eq. (7) or
(11) would satisfy the boundary-value problem from that
point forward. Landing-site redesignation, which can
arbitrarily stretch or shrink the trajectory, would produce
an unnecessarily severe guidance response if <span style="color: blue;"><i>T</i></span> were not
correspondingly adjusted. Because <span style="color: blue;"><i>T</i></span> is arbitrary, it can be
computed to satisfy an additional boundary constraint. In
Apollo, this additional constraint is imposed on the
downrange (Z) component of jerk. Thus the Z-component of the
jerk polynomial of Eq. (9) is solved for <span style="color: blue;"><i>T</i></span> by using a target
Z-component of jerk <span style="color: blue;"><i>JTGz</i></span>. Separating this scalar cubic
polynomial from Eq. (9) yields
<br />
<br />
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<br />
One root of this cubic is the required time <span style="color: blue;"><i>T</i></span>.
<br />
<br />
An alternate criterion for computing <span style="color: blue;"><i>T</i></span> reduces the
propellant-consumption penalty of downrange landing-site
redesignations. <u>Although extensively tested, the alternate
was developed too late for incorporation in the LGC program.</u>
The alternate criterion sets the downrange position error to
zero. Thus <span style="color: blue;"><i>T</i></span> is one root of the quartic
<br />
<br />
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<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Braking-Phase Targeting Objectives
</b></span><br />
<br />
"The near-optimal transfer provided by P63 targeting must
satisfy a throttling constraint that the DPS be operated
within the permitted-thrust region for, nominally, the final
two minutes of the phase. This throttling duration absorbs
dispersions in DPS performance and errors in lunar terrain
modeling. With a total propellant consumption of over
6,600-kg, Yang (/8/) shows that the Apollo guidance and
targeting are within 16-kg of an optimal trajectory
satisfying the same throttling constraint.
<br />
<br />
To provide thrust within the 11 to 65% region for the last
two minutes of P63, the targets are chosen to produce a
constant thrust level of about 57% of rated thrust at P63
terminus. The targeting program accomplishes this by
constraining the magnitude of the terminal
thrust-acceleration vector to be
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
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<br />
and constraining the Z-component of terminal jerk to be
(essentially)
<br />
<br />
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<br />
<br />
where <span style="color: blue;"><i>F</i></span> is the required terminal thrust, <span style="color: blue;"><i>M</i></span> is the estimated
terminal mass, <span style="color: blue;"><i>M_dot</i></span> is the estimated terminal mass flow
rate (negative), and <span style="color: blue;"><i>K</i></span> is a jerk coefficient to account for
the vertical component of thrust. The targeting program
achieves the two minute duration of constant thrust by
adjusting the initial range.
<br />
<br />
Properly targeted, the guidance algorithm commands during
most of P63 a thrust-acceleration in excess of what can be
achieved. The throttle routine multiplies this
thrust-acceleration command by the estimated mass to yield
the <i><u>guidance thrust command</u></i> (<span style="color: blue;"><i>GTC</i></span>), and provides maximum
thrust until the <span style="color: blue;"><i>GTC</i></span> falls below 57%.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSsDUGmI0ECZbPeXn9sQW7svSbG4wlYQEmB35O4X8eSEG6WTTsXHokctINmVUjQl0kR8rMZp70auTYpL-wYZ23IKds_mX9dOpqDeCaPqJOK-5Bu8LWbUfgqAIoT7hM_9HxUn87wnFe6IyL/s1600/Fig_5_Thrust_Profile.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSsDUGmI0ECZbPeXn9sQW7svSbG4wlYQEmB35O4X8eSEG6WTTsXHokctINmVUjQl0kR8rMZp70auTYpL-wYZ23IKds_mX9dOpqDeCaPqJOK-5Bu8LWbUfgqAIoT7hM_9HxUn87wnFe6IyL/s400/Fig_5_Thrust_Profile.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 5. Actual Thrus Profiles and Guidance Command Thrust Profiles During P63.</span></i></span></td></tr>
</tbody></table>
<br />
Figure 5 illustrates
the profiles of <span style="color: blue;"><i>GTC</i></span> and actual thrust for a properly
targeted P63 phase and shows the effects of adjustments of
the ignition time and of the DPS thrust level.
<br />
<br />
The targeting program computes the P63 targets by projecting
computed terminal conditions forward typically 60 seconds.
Although the targets are projected, they are computed to
produce the required terminal conditions on a nominal
trajectory. Trajectory dispersions cannot be eliminated
prior to the target point, but they can be reduced
sufficiently by terminus to achieve the targeting
objectives. Both the ignition time and the projected targets
are computed iteratively using a descent simulation in the
iteration loop."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Approach-Phase Targeting Objectives
</b></span><br />
<br />
"The P64 targets are computed to provide lunar-surface
visibility until about 5 seconds before terminus, and
continuous throttling. In addition, the P64 targets are
computed to produce at terminus a matched set of values for
the Z-components of acceleration, velocity, and position
such that, in the nominal case, the P66 algorithm will
produce no initial pitch transient and will simultaneously
null the Z-components of velocity and position. Unlike P63,
the P64 reference trajectory can be determined in closed
form from specified trajectory constraints. Thus the
projected targets are computed without numerical iteration."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Landing-Site Redesignation Procedure
</b></span><br />
<br />
"To steer the LM via the automatic P64 guidance to a
visually selected landing site, the commander uses an
iterative procedure akin to steering an automobile. The
procedure consists of
<br />
<ol>
<li>identifying the current landing site where the
LGC would take him in the absence of intervention
and</li>
<li>steering the current site into coincidence with
his visually selected site by commanding incremental
landing-site displacements (redesignations).
</li>
</ol>
<br />
Because the P64 targets are defined in the guidance
coordinate frame, which is repetitively erected through the
landing site, the P64 target point is displaced accordingly.
<br />
<br />
To identify the currently selected landing site to the
astronauts, the LGC
<br />
<ol>
<li>orients the LM about the thrust axis to
superimpose the landing point designator (LPD)
reticles (see Figure 1) on the current site and</li>
<li>displays a number which is read by the LM pilot
and vocally relayed to the commander.
</li>
</ol>
<br />
By sighting through the indicated point of the LPD reticles,
the commander identifies the current site. He registers his
eye by superimposing the two LPD reticles, one of which is
painted on the inside window panel, and one on the outside
window panel. The separation between reticles is 2.5 cm.
<br />
<br />
By manipulating his controller left, right, forward, or aft,
the commander directs the LGC to displace the landing site
(and the P64 targets) along the lunar surface by a
correspondingly directed fixed angular increment (1°) with
respect to the current line of sight.
<br />
<br />
The LGC redirects the thrust to guide to the redesignated
(now current) site, and reorients about the thrust axis to
maintain superposition of the reticles on the current site.
The commander can continue this redesignation process -
steering the current landing site into coincidence with his
chosen site - until 10 seconds before reaching the P64
target point, at which time P66 is initiated."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>P63, P64 Guidance Algorithm
</b></span><br />
<br />
"Figure 6 illustrates the P63, P64 Guidance Algorithm.<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgi3n6InUhcRJnmzw2O3G465lM7T6Xupta-KM0HxHGr_U0RxKkCbngN4aOh5W_DP5Clxw8SC-LT7ZMO66UEj6nZcTTiLLHBjJ2viBOOavnsizzETapdK1dXHWzJDKUSCnu76syyD-G3rMvw/s1600/Fig_6_P64_P64_Block_Diagram_new.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgi3n6InUhcRJnmzw2O3G465lM7T6Xupta-KM0HxHGr_U0RxKkCbngN4aOh5W_DP5Clxw8SC-LT7ZMO66UEj6nZcTTiLLHBjJ2viBOOavnsizzETapdK1dXHWzJDKUSCnu76syyD-G3rMvw/s400/Fig_6_P64_P64_Block_Diagram_new.png" width="132" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 6. P63, P64 Guidance Algorithm.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
As
shown in Figure 3, the algorithm receives guidance targets,
the current state vector, and the current gravity vector as
inputs and issues a thrust-acceleration command, a unit
thrust command, and a unit window command as outputs.
<br />
<br />
Because the landing site moves due to lunar rotation and
landing-site redesignation, the LM is guided with respect to
the guidance coordinate frame, which is erected through the
landing site each pass. Guidance targets are fixed in this
floating frame. Other inputs and all outputs are expressed
in platform coordinates.
<br />
<br />
The landing site vector <span style="color: blue;"><i>L_P</i></span> is updated for lunar rotation
(Eq. (6.1)) using an approximate algorithm that avoids
computation of trigonometric functions, yet preserves the
magnitude of the lunar radius. The algorithm accounts for
the lunar rotation rate <span style="color: blue;"><i>V_MOONP</i></span> and the elapsed clock-time
since the preceding update (<span style="color: blue;"><i>t - tOLD</i></span>).
<br />
<br />
For the landing-site redesignation algorithm (Eqs. (6.2) -
(6.7)), whenever the commander manipulates the controller
(Figure 1) in the automatic mode, the LGC is interrupted and
the azimuth command count (<span style="color: blue;"><i>NCAZ</i></span>) or the elevation command
count (<span style="color: blue;"><i>NCEL</i></span>) is incremented or decremented according to the
direction of manipulation. The redesignation algorithm
fetches and resets to zero the <span style="color: blue;"><i>NCAZ</i></span> and <span style="color: blue;"><i>NCEL</i></span> accumulators
and rotates <span style="color: blue;"><i>L_OSP</i></span> (the unit line-of-sight vector to the
current landing site) by 1° per count (Eq. (6.3)). If <span style="color: blue;"><i>NCAZ</i></span>
and <span style="color: blue;"><i>NCEL</i></span> are both zero, the redesignation algorithm has no
effect. Given that attitude control maintains coincidence of
the ZB, XB plane and <span style="color: blue;"><i>L_OSP</i></span>, the rotations of <span style="color: blue;"><i>L_OSP</i></span> are about
two axes normal to <span style="color: blue;"><i>L_OSP</i></span>. Elevation redesignations rotate
<span style="color: blue;"><i>L_OSP</i></span> about the YB-axis, and azimuth redesignations rotate
<span style="color: blue;"><i>L_OSP</i></span> about an axis normal to <span style="color: blue;"><i>L_OSP</i></span> in the ZB, XB plane.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQOFyjUTtGeisMNm1E1UL64FKLRxMrYhZgwTHMiO69cr2Hy-Chm9-ac3EWTapIaR-AzKK82PLI4F294mR9toMUvfVtwh3qo2GxdMC1heCndJ6XJqzwUQtMygknacs-dZM4iAnPd14fAnHO/s1600/Fig_7_Redesignation.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="327" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQOFyjUTtGeisMNm1E1UL64FKLRxMrYhZgwTHMiO69cr2Hy-Chm9-ac3EWTapIaR-AzKK82PLI4F294mR9toMUvfVtwh3qo2GxdMC1heCndJ6XJqzwUQtMygknacs-dZM4iAnPd14fAnHO/s400/Fig_7_Redesignation.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 7. Landing-site Redesignation Geometry.</span></i></span></td></tr>
</tbody></table>
<br />
The
landing-site redesignation geometry shown in Figure 7
depends upon the defined LM platform orientation, namely
that the XP-axis is near vertical through the landing site.
The constraint that <span style="color: blue;"><i>LOSPx</i></span> be at least as negative as -0.02
(Eq. (6.5)) prevents redesignating the landing site beyond
the horizon. Equation (6.7) computes the displaced point
near the surface shown in Figure 7 and places the
redesignated site directly beneath this point.
<br />
<br />
The displayed LPD angle (theta_LPD, Eq. (6.8)) is the angle
between <span style="color: blue;"><i>L_OSP</i></span> and the ZB-axis.
<br />
<br />
The computation of the state vector in guidance coordinates
(Eq. (6.9))places the origin of the guidance frame at the
landing site and yields the velocity of the LM relative to
the lunar surface.
<br />
<br />
Target-referenced time T is computed using Newton's method
starting with a good estimate (Eqs. (6.12) - (6.13)). Note
that the denominator of Eq. (6.12)is the derivative of the
numerator.
<br />
<br />
The guidance equation (Eq. (6.15)) is identical to Eq. (11).
The thrust acceleration command( Eqs.(6.16)- (6.17)) is
merely the total acceleration command minus current gravity
G_P, and the unit thrust command (Eq. (6.18)) is the
direction of the thrust-acceleration command. The so-called
radial-acceleration guidance correction described in
reference /9/ is rendered unnecessary by current targeting
techniques and is omitted from this report, although present
in the LGC program.
<br />
<br />
<u>The computation of the unit window command presented here
is a simplification of the LGC coding which produces the
same result.</u> The object is to keep the landing site in the
center of vision (superimpose the LPD reticles on the
current site) whenever the geometry permits and, otherwise,
to command a forward-facing attitude.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixBlh4-26wFaj8V7IEbNOSN6guT6973GX205UcZbth0bKQfu2GUV4lGzA5QrT7pAKm0iZ3BpaPB927Z6ShCBYSRLQn_gD_gZIzChyWD3BQJLcfymDjdh-J8lKDitn2Ejb2EtmRNvHNFcFj/s1600/Fig_8__.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="372" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixBlh4-26wFaj8V7IEbNOSN6guT6973GX205UcZbth0bKQfu2GUV4lGzA5QrT7pAKm0iZ3BpaPB927Z6ShCBYSRLQn_gD_gZIzChyWD3BQJLcfymDjdh-J8lKDitn2Ejb2EtmRNvHNFcFj/s400/Fig_8__.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i><span style="color: #cc0000;"><span style="font-size: small;">Figure 8. Why the<br />landing site cannot always be kept in the center of vision.</span></span></i></td></tr>
</tbody></table>
<br />
<br />
Figure 8 shows why the
landing site cannot always be kept in the center of vision.<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLgFk-gfINOTy1_vMTAEBxx5qwARA1GDhlLfHaS3DzAWxgszydxV_E-x02vjbNJBgyS5mMV2miEGWxsInhWFtfVGCzNs19CXDyqIxm_8WP_rusHDW2X8bWMV1z8Em77r7Hc4O0Cf2wHHyr/s1600/Fig_9__.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="328" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhLgFk-gfINOTy1_vMTAEBxx5qwARA1GDhlLfHaS3DzAWxgszydxV_E-x02vjbNJBgyS5mMV2miEGWxsInhWFtfVGCzNs19CXDyqIxm_8WP_rusHDW2X8bWMV1z8Em77r7Hc4O0Cf2wHHyr/s400/Fig_9__.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 9. Geometry pertinent to computation of the
unit window command.</span></i></span> </td></tr>
</tbody></table>
<br />
<br />
Figure 9 shows the geometry pertinent to computation of the
unit window command <span style="color: blue;"><i>U_NWCP</i></span>. Commanding the line-of-sight
vector (<span style="color: blue;"><i>U_NWCP = L_OSP</i></span>) alines the reticles with the landing
site; commanding the forward vector (<span style="color: blue;"><i>U_NWCP = F_ORP</i></span>)
produces a forward facing attitude. If the first alternative
is chosen (<span style="color: blue;"><i>U_NWCP = L_OSP</i></span>) the LM will rotate about the
XB-axis to aline the YB-axis with the vector <span style="color: blue;"><i>L_OSP x C_BPX</i></span>.
Thus the direction of <span style="color: blue;"><i>L_OSP x C_BPX</i></span> indicates whether a
normal forward-facing attitude or an abnormal attitude would
result from the command <span style="color: blue;"><i>U_NWCP = L_OSP</i></span>. In addition, the
magnitude of <span style="color: blue;"><i>L_OSP × C__BPX </i></span>measures the degree of
indeterminacy in the command <span style="color: blue;"><i>U_NWCP = L_OSP</i></span>. The projection
(PROJ, Eq. (6.20)) of <span style="color: blue;"><i>L_OSP x C_BPX</i></span> on the YG-axis detects
both the magnitude and the direction of <span style="color: blue;"><i>L_OSP × C_BPX</i></span>. Thus
PROJ is used as the criterion for mixing <span style="color: blue;"><i>L_OSP</i></span> and <span style="color: blue;"><i>F_ORP</i></span>
into <span style="color: blue;"><i>U_NWCP</i></span>. If the descent trajectory is planar, the mixing
(Eq. (6.21)) yields <span style="color: blue;"><i>U_NWCP = L_OSP</i></span> for <span style="color: blue;"><i>theta_LPD</i></span> ≤ 65°,
<span style="color: blue;"><i>U_NWCP = F_ORP</i></span> for <span style="color: blue;"><i>theta_LPD</i></span> ≥ 75° , and <span style="color: blue;"><i>U_NWCP</i></span> a mixture
linear with cos <span style="color: blue;"><i>theta_LPD</i></span> for 65° ‹ <span style="color: blue;"><i>theta_LPD</i></span> ‹ 75°.
Regardless of whether the trajectory is planar or nonplanar,
it is never possible to command a side-facing or a
rear-facing attitude.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhFlmlbYZf3dN6u9mXKiAX84WrrmNh-QPG9RTf1qyn6csJcM8iBoxqi5exysZqGXI3qWT8_1K5orUqb4bNiymJ-iKmcQswZOTbYeqGCCoMpatHbWE7BR-1A9dho2ksFDePEMZbX8Mo8A2p/s1600/Fig_10.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="321" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhFlmlbYZf3dN6u9mXKiAX84WrrmNh-QPG9RTf1qyn6csJcM8iBoxqi5exysZqGXI3qWT8_1K5orUqb4bNiymJ-iKmcQswZOTbYeqGCCoMpatHbWE7BR-1A9dho2ksFDePEMZbX8Mo8A2p/s400/Fig_10.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 10. Plan View of Guidance-coordinate-frame Erection.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Erection of the guidance coordinate frame (Eqs. (6.22) -
(6.24)) is illustrated in Figure 10. With <span style="color: blue;"><i>K=1</i></span> in P63, the
guidance coordinate frame orientation about the vertical
XG-axis is such that the YG-component of jerk would reach
zero at the target point if the trajectory were flown there
(see reference /5/). With <span style="color: blue;"><i>K=0</i></span> in P64, the ZG-axis is in the
vertical plane containing the line-of-sight vector. For
cross range landing-site redesignations, setting <span style="color: blue;"><i>K=0</i></span> in P64
was found to consume less DPS propellant than setting <span style="color: blue;"><i>K=1</i></span> to
null the cross range jerk at the target point."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>P63 Ignition Algorithm
</b></span><br />
<br />
"Trajectory dispersions preceding P63 require an accurate
ignition time and attitude to be computed to
<br />
<ol>
<li>avoid excessive variations of the time duration
of throttle control in P63 and</li>
<li>to avoid commanding an excessive attitude
transient the first time the P63, P64 Guidance
Algorithm is processed.
</li>
</ol>
<br />
The P63 ignition procedure consists of:
<br />
<ol>
<li>Computing onboard the precise ignition time and
attitude about 10 minutes in advance of ignition</li>
<li>Orienting the LM to the ignition attitude</li>
<li>Initiating reaction control system ullage 7.5
seconds prior to ignition</li>
<li>Igniting the DPS at minimum thrust and holding
constant thrust and constant attitude for 26
seconds, the maximum time required for the DAP to
orient the DPS trim gimbal system to point the
thrust vector through the LM center of mass</li>
<li>Connecting the guidance algorithm, which
immediately commands maximum thrust and begins
commanding an attitude profile according to the
current state vector and the P63 targets.
</li>
</ol>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjh93FxI-TJDMjDkip4Kf52gyMJftlNFhChhX08c1DtAsjbC5Jyj09w7G0bIXxmenS6VQlR428v_vfb0-YwBMHDM7y3KbbmAnCfEncqtK_6djlBd9Dd6UgBlNTdDlbUVuG8MZKcqVfU4cfV/s1600/Fig_11_P63_Ignition_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjh93FxI-TJDMjDkip4Kf52gyMJftlNFhChhX08c1DtAsjbC5Jyj09w7G0bIXxmenS6VQlR428v_vfb0-YwBMHDM7y3KbbmAnCfEncqtK_6djlBd9Dd6UgBlNTdDlbUVuG8MZKcqVfU4cfV/s400/Fig_11_P63_Ignition_Block_Diagram.png" width="197" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 11. P63 Ignition Algorithm.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
To determine the required ignition attitude, the ignition
algorithm (Figure 11) calls the guidance algorithm as a
subroutine. The ignition algorithm supplies inputs
consisting of an accurate extrapolation of the state vector
and the corresponding gravity vector (both valid at
<span style="color: blue;"><i>GUIDTIME</i></span>, the estimated clock-time of the first P63 guidance
pass). In preparation, Eqs. (11.1) - (11.5) initialize
guidance algorithm inputs. On the first iteration, the state
vector extrapolation represented by Eq. (11.6) is performed
by an orbital integration routine and, on subsequent
iterations, by a Kepler routine. Equation (11.9) corrects
the extrapolated velocity vector by the velocity increment
imparted during the 26 seconds of minimum thrust preceding
this point. (The errors due to not correcting the
extrapolated position vector and not correcting for ullage
are negligible.) The guidance algorithm produces a unit
thrust command <span style="color: blue;"><i>U_NFCP</i></span>, which is the direction to point the
XB-axis. Because the direction of the velocity correction is
unknown on the first iteration, the above procedure is
iterated thrice.
<br />
<br />
An outer ignition-algorithm loop accounts for dispersions
with respect to the nominal trajectory. Equations (11.11) -
(11.12) adjust <span style="color: blue;"><i>GUIDTIME</i></span> to correct the <span style="color: blue;"><i>RGz</i></span> component of
position at <span style="color: blue;"><i>GUIDTIME</i></span> as<br />
<ol>
<li>a linear function of the dispersion in orbital
speed <span style="color: blue;"><i>VG</i></span> and of the dispersion in the <span style="color: blue;"><i>RGx</i></span> component
of position (essentially altitude) and</li>
<li>as a quadratic function of the out-of-plane
position <span style="color: blue;"><i>RGy</i></span>.
</li>
</ol>
<br />
<span style="color: blue;"><i>RBRIGx</i></span> and <span style="color: blue;"><i>RBRIGz</i></span> are nominal initial altitude and range
components of position in guidance coordinates; <span style="color: blue;"><i>VBIRIG</i></span> is
the nominal initial speed; and <span style="color: blue;"><i>KX</i></span>, <i><span style="color: blue;">KY</span></i>, and <span style="color: blue;"><i>KV</i></span> are correction
coefficients. The nominal initial altitude, range, and speed
are computed by the targeting program. The correction
coefficients are computed using a manual procedure based on
descent simulations.
<br />
<br />
When converged, this process yields a precise time and
attitude for igniting the DPS. Trajectory dispersions result
in typical variations of 2 seconds in the time duration of
throttle control and typical attitude transients of 2
milliradians commanded by the guidance algorithm on the
first P63 pass."
<br />
<br />
<br />
<br />
<br />
<h4>
TERMINAL-DESCENT-PHASE GUIDANCE
</h4>
<br />
"Horizontal and vertical velocity are controlled in P66 by
completely independent algorithms. P66 provides a
nonautomatic attitude-hold mode in which the commander can
control the LM attitude to translate or not, as he wishes,
horizontally over the lunar surface. P66 issues no unit
window command; yaw is controlled manually. A description of
P66 including the nonautomatic modes is provided by Eyles.
(/10/)"
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>P66 Horizontal Guidance Algorithm
</b></span><br />
<br />
"The P66 horizontal guidance algorithm (Figure 12),
processed once every two seconds, nulls the horizontal
components of velocity relative to the lunar surface by
directing the thrust vector a small angle away from vertical
in opposition to horizontal velocity.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzAqN3pOSIKCbXy79K7454EDZIYlUz_zm0P81mPDFlWYP9_Okp9dLhzyRq0BoesbiSM4JTvZ3kW-cnPFgYX-XilWfOO1RNt8OTGCll9u2g11f9nUdGmAqtfIJ31UozuTrZP0g0bOF1L_gM/s1600/Fig_12_P66_Horizontal_Guidance_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzAqN3pOSIKCbXy79K7454EDZIYlUz_zm0P81mPDFlWYP9_Okp9dLhzyRq0BoesbiSM4JTvZ3kW-cnPFgYX-XilWfOO1RNt8OTGCll9u2g11f9nUdGmAqtfIJ31UozuTrZP0g0bOF1L_gM/s400/Fig_12_P66_Horizontal_Guidance_Block_Diagram.png" width="267" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 12. P66 Horizontal Guidance Algorithm.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The horizontal
algorithm neither measures nor commands thrust-acceleration
magnitude; the algorithm is derived on the assumption that
the vertical component of thrust-acceleration equals lunar
gravity.
<br />
<br />
Just as velocity feedback damps a position control loop,
acceleration feedback damps a velocity control loop. Because
of the sampled-data character of the system, a good measure
of current acceleration is the acceleration commanded the
preceding pass. The P66 horizontal algorithm feeds back the
velocity error (current velocity <span style="color: blue;"><i>VPy</i></span>, <span style="color: blue;"><i>VPz</i></span> minus lunar
surface velocity <span style="color: blue;"><i>VMOONPy</i></span>, <span style="color: blue;"><i>VMOONPz</i></span>) and, to provide the
required damping, feeds back a fraction of the
thrust-acceleration command from the preceding pass (Eqs.
(12.2) - 12.3)). On the first P66 pass, the thrust
acceleration fed back is that commanded the final P64 pass.
<br />
<br />
The direction of the thrust-acceleration command is limited
to 20° from vertical (Eqs. (12.4) and (12.5)) to maintain a
nearly erect LM attitude. The LIMIT function of two
arguments limits the magnitude of the first argument to the
value of the second argument.
<br />
<br />
The unit thrust command (Eq. (12.6)) is the direction of the
limited thrust acceleration command.
<br />
<br />
The assumption in generating horizontal commands that the
vertical component of thrust-acceleration equals lunar
gravity (Eq. (12.1)) is realized only if the LM is not
accelerating vertically. The purpose of ignoring vertical
acceleration is to eliminate coupling from ROD inputs to LM
attitude. The effect of vertical acceleration, which occurs
whenever the commander manipulates the ROD switch, is to
modulate the gains of the horizontal channels. This gain
modulation is negligible because only limited changes in the
descent rate will ever be commanded; the vertical
acceleration can be significantly nonzero only for short
periods of time.
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>P66 Vertical (ROD) Guidance Algorithm
</b></span><br />
<br />
"The ROD guidance algorithm, processed once per second,
controls altitude rate to the reference value by throttling
the DPS. The ROD algorithm has no control over the LM
attitude; the thrust-acceleration command it issues accounts
for any non-vertical orientation of the thrust vector.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK_HC4rwlQsPeup2Udm-p4uMUC2pmlWugi_UmMGmHmCAhcW2KviCicS9hJGdzjWvZ7ZR07a3Lz-r6BpGCfVh39WK0uilbdzgNeVwwqZ-Ujv4twRW3bSK0MBiaq19vDkAGqQS_kX17SdeXv/s1600/ROD_Switch_Panel5.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiK_HC4rwlQsPeup2Udm-p4uMUC2pmlWugi_UmMGmHmCAhcW2KviCicS9hJGdzjWvZ7ZR07a3Lz-r6BpGCfVh39WK0uilbdzgNeVwwqZ-Ujv4twRW3bSK0MBiaq19vDkAGqQS_kX17SdeXv/s400/ROD_Switch_Panel5.png" width="326" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 60. The ROD switch is located on the panel 5 in LM cockpit.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The object of the ROD guidance is to respond rapidly without
overshoot to ROD increment commands. The algorithm provides
a time constant of 1.5 seconds, even though the sample
interval is 1.0 second, by capitalizing on the sampled-data
character of the system. Using a computed estimate of the
total acceleration at the ROD sample instant, the ROD
algorithm extrapolates sample-instant measured velocity by
the effective transport lag of 0.35 second and thus commands
an acceleration appropriate for the velocity error at the
time the acceleration command will be realized. A sampled
data analysis (reference /11/) shows that the compensation
for effective transport lag is highly effective in
stabilizing the vertical channel. The significant system
dynamics reduce to a single zero and two poles in the plane.
The zero is
<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigvpYsajESmDbh43ff9UwY1Rubvv51OlI9sWyc1OpBj9-FYAcAtW_SpuI5L6EwWDFnC_0C5Qh5_ySvGWyM95x1yDaqZJP39m26aMY3EFnrD5NZTuPms40LRS_pEX2mjxci2lRH3OQ2VlFb/s1600/eq_68.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="66" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEigvpYsajESmDbh43ff9UwY1Rubvv51OlI9sWyc1OpBj9-FYAcAtW_SpuI5L6EwWDFnC_0C5Qh5_ySvGWyM95x1yDaqZJP39m26aMY3EFnrD5NZTuPms40LRS_pEX2mjxci2lRH3OQ2VlFb/s400/eq_68.png" width="400" /></a></div>
<br />
<br />
One pole is at the origin, and the second pole is
<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9x0TF1bVM6eHXGjotOdtUURvGneKamspul2QSWDTQVeprPFX2utWN0ZG8CPfY4kFyDQC-k3F-t4S7bRLueogC38cQVmeui7pR1bvll_AYL0pdAenTYqFxLUWX707K78cyTjXPbi4JSDgU/s1600/eq_69.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="56" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9x0TF1bVM6eHXGjotOdtUURvGneKamspul2QSWDTQVeprPFX2utWN0ZG8CPfY4kFyDQC-k3F-t4S7bRLueogC38cQVmeui7pR1bvll_AYL0pdAenTYqFxLUWX707K78cyTjXPbi4JSDgU/s400/eq_69.png" width="400" /></a></div>
<br />
The poles are the same as for an ideal system containing
neither a transport lag nor an extrapolation.
<br />
<br />
The ROD algorithm has been simplified for this report as
follows:
<br />
<br />
<span style="color: purple;"><span style="color: blue;"><b>1.</b></span> </span>In the LGC coding, the ROD algorithm begins each
pass by reading the accelerometers and recording the
time at which they are read. This time is called the
ROD sample instant. ROD sample instants occur
irregularly, but the interval between them, called
the ROD sample interval, averages 1 second. The
accelerometer readings are used to compute
<br />
<ul>
<li>a) the three-component current velocity
vector valid at the ROD sample instant,
based on updating the velocity vector
supplied by the state vector update routine
(SVUR, Figure 3), and</li>
<li>b) a thrust-acceleration measurement which
is the average over the ROD sample interval.
</li>
</ul>
To compute the velocity vector it supplies, the SVUR
also reads the accelerometers, each pass, at the
SVUR sample instant occurring at regular 2-second
intervals. The irregular ROD sample instants are
essentially asynchronous with the regular SVUR
sample instants. Consequently the interactions
between the ROD algorithm and the SVUR in updating
the SVUR-supplied velocity vector are extremely
intricate. In this report, the data processed by the
ROD algorithm are shown as inputs. How these inputs
are obtained is described in reference /9/.
<br />
<br />
<span style="color: purple;"><span style="color: blue;"><b>2.</b></span> </span>Although the vertical orientation of the XP-axis
is capitalized upon by several LGC routines,
including the P66 horizontal algorithm and the
landing-site redesignation algorithm, the LGC ROD
algorithm laboriously manipulates complete vector
state data to maintain validity for any platform
alignment. Presented here is the scalar equivalent
valid for the lunar-landing platform alignment.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjV2mwk2-SgDzOTACKWfXZJwnAAj9cwIUc9vIlXNVaMmc1xSX2JEEIbtHs1b2xyZxcwQsXFtOzDV65KjT1M6jx7wVK_gmlmXkltuUTmHarsOvpFqOzA0MrFfg3_1S5qOhBmYV1-7kum126R/s1600/Fig_13_P66_Vertical_%2528ROD%2529_Guidance_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjV2mwk2-SgDzOTACKWfXZJwnAAj9cwIUc9vIlXNVaMmc1xSX2JEEIbtHs1b2xyZxcwQsXFtOzDV65KjT1M6jx7wVK_gmlmXkltuUTmHarsOvpFqOzA0MrFfg3_1S5qOhBmYV1-7kum126R/s400/Fig_13_P66_Vertical_%2528ROD%2529_Guidance_Block_Diagram.png" width="232" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 13. P66 Vertical (ROD) Guidance Algorithm.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 13 shows the ROD algorithm. The inputs are all valid
at the ROD sample instant. Equation (13.1) computes the
sample-instant total vertical acceleration by adding, to the
thrust-acceleration measurement (averaged over the ROD
sample interval), current gravity and a correction for the
throttle change concluding the preceding ROD pass. The
thrust correction increment theta_FA is supplied by the
Throttle Routine. Equation (13.2) extrapolates the
sample-instant measured velocity. The commanded vertical
velocity (reference altitude rate) is initialized as the
vertical velocity existing at the time P66 is initiated, and
is incremented or decremented by Eq. (13.3) each ROD pass
according to the ROD commands issued by the commander since
the preceding ROD pass. Equation (13.5) first computes the
total vertical acceleration required as the negative of the
extrapolated velocity error divided by the ROD time constant
(1.5 seconds). The equation then obtains the required
vertical thrust-acceleration by subtracting current gravity.
Finally, dividing by <span style="color: blue;"><i>CBPxx</i></span>, which is the cosine of the angle
between the XB-axis and the vertical XP-axis, Eq. (13.5)
yields the thrust-acceleration command <span style="color: blue;"><i>AFCP</i></span>. To avoid an
empirically discovered instability which occurs when the
throttle routine or the DPS cannot comply with the
thrust-acceleration command from P66, Eqs. (13.6) and (13.7)
restrict <span style="color: blue;"><i>AFCP</i></span> to produce thrust within the permitted-thrust
region."
<br />
<br />
<br />
<h4>
POWERED-FLIGHT ATTITUDE-MANEUVER ROUTINE
</h4>
<br />
"A link in the attitude control chain of command, the
Powered-flight Attitude maneuver routine (ATT) connects the
various powered-flight guidance programs to the DAP. The
functions of ATT are:<br />
<ol>
<li>For the small attitude changes normally required
each guidance cycle, ATT commands a maneuver of
constant rate such as to achieve the required
attitude 2 seconds later.</li>
<li>For gross attitude maneuvers which may be
required at phasic interfaces or upon abort, ATT
commands a rate-limited maneuver which may extend
over several guidance cycles.</li>
<li>For all attitude maneuvers ATT avoids the
gimbal-lock region (middle gimbal angle › 70°
magnitude). ATT issues a gimbal-lock alarm code if
and only if the commanded attitude computed from
guidance inputs lies within the gimbal-lock region.
ATT commands a maneuver which circumvents the
gimbal-lock region and issues no gimbal-lock alarm
code when the most direct path to the commanded
attitude passes through the gimbal-lock region.
</li>
</ol>
<br />
Switching from a descent program to an abort program may
produce up to 180° change in commanded thrust direction. A
break with traditional approaches, ATT makes gimbal lock
during any maneuver inherently impossible by<br />
<ol>
<li>computing commanded gimbal angles,</li>
<li>limiting the magnitude of the middle commanded
gimbal angle, and</li>
<li>issuing to the DAP a series of incremental
attitude-maneuver commands that monotonically* drive
the gimbal angles from their current values to their
commanded values. <span style="color: #274e13;"><i>[*Except the outer gimbal angle profile may not be monotonic
in the geometrically complex case of a large maneuver about
multiple axes at substantial middle gimbal angle and with
magnitude limiting of the X-axis attitude angle change on at
least one pass through ATT.]
</i></span></li>
</ol>
<br />
Provided the attitude is not
currently in gimbal lock, and given that the middle
commanded gimbal angle is magnitude limited at the
gimbal-lock boundary, it is inherently impossible to
maneuver through gimbal lock; the middle gimbal
angle is confined to the range between its current
and commanded values. Other attitude-maneuver
schemes with appended gimbal-lock avoidance require
more computation to produce similar maneuvers.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3qtgodeLjzlEB6NgvxMuh3wzeOo_7DHrQX0U9s5m6q3v0V-h9ad8nlBLerrLAlfbozxjJUzEevO1azymzNuTAfqnuiSupKQdNb1mkDLBEkl-GTbDvj2drBjKS1qSage3enrHXScuyHqlX/s1600/Fig_14_LM_Powered_Flight_Attitude_Control.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh3qtgodeLjzlEB6NgvxMuh3wzeOo_7DHrQX0U9s5m6q3v0V-h9ad8nlBLerrLAlfbozxjJUzEevO1azymzNuTAfqnuiSupKQdNb1mkDLBEkl-GTbDvj2drBjKS1qSage3enrHXScuyHqlX/s400/Fig_14_LM_Powered_Flight_Attitude_Control.png" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 14. LM Powered Flight Attitude Control Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 14 presents an overview of the LM powered-flight
attitude control process, including some information on the
procedures on the DAP side of the interface. Two
computational coordinate frames are introduced. From
guidance and navigation inputs, ATT computes a
commanded-body frame (tag CB) to represent the commanded
attitude inherent in the input vectors. From ATT inputs, the
DAP computes reference gimbal angles to compare with
measured gimbal angles for computing the attitude errors.
The reference gimbal angles define a reference-body frame
(tag RB). ATT computes that the attitude errors are zero
when these two computational coordinate frames coincide. Of
course, there may be DAP control errors undetected by ATT,
but any thrust pointing error is detected in the steady
state by a thrust-direction filter, and corrected.
<br />
<br />
<br />
The guidance and navigation inputs to ATT, shown in Figure
14, consist of a unit thrust command, a unit window command,
and a thrust-acceleration measurement. ATT processes the
thrust-acceleration measurement in a thrust-direction filter
to determine an estimated unit thrust vector with respect to
the reference-body frame. Correcting for the offset of the
estimated unit thrust vector with respect to the XRB-axis,
ATT uses the unit thrust command and the unit window command
to erect the commanded-body frame. From the commanded-body
frame matrix, ATT extracts commanded gimbal angles which it
compares with the reference gimbal angles to generate inputs
to the DAP. Ten times per second, the DAP updates the
reference attitude and generates the corresponding control
commands. The dynamic response is sufficiently fast and
tight that the reference attitude is a good measure of
instantaneous spacecraft attitude.
<br />
<br />
<br />
A feature of this configuration is that, although ATT runs
at a sample rate of 2 seconds, close to the fuel-slosh
resonant frequency at certain points in the mission, it
avoids exciting fuel slosh by avoiding all coupling with the
actual spacecraft attitude except through the slow
thrust-direction filter.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrouosi9a3Ez1td0TBxItY-yfxSwZIyj4yzXt-OkznJfkmS3EFxoJKkZY8XUrmGlM6rLKmLJySYaOK8m-EU3fluYG9ikflHSLoM6jeeGuiIipUVrBXiTo_Ee2K5kEOK4f0gTFzZiS9i-r-/s1600/Fig_15_Powered_Flight_Attitude_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgrouosi9a3Ez1td0TBxItY-yfxSwZIyj4yzXt-OkznJfkmS3EFxoJKkZY8XUrmGlM6rLKmLJySYaOK8m-EU3fluYG9ikflHSLoM6jeeGuiIipUVrBXiTo_Ee2K5kEOK4f0gTFzZiS9i-r-/s400/Fig_15_Powered_Flight_Attitude_Block_Diagram.png" width="148" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 15. Powered-flight Attitude Maneuver Routine Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 15 details the Powered-flight Attitude-maneuver
routine. The thrust direction filter computes the
thrust-acceleration measurement in reference-body
coordinates by constructing the required transformation from
the reference gimbal angles (Eq. (15.1)). The change in
thrust direction is limited on each cycle to 7-mr (Eqs.
(15.3) and (15.4)), the maximum travel of the trim gimbal in
2 seconds. The total excursion of the estimated unit thrust
vector is limited to 129-mr (Eqs. (15.5) and (15.6)), the
mechanical excursion limit of the trim gimbal plus
mechanical deflection and thrust offset with respect to the
nozzle. The X-component of the estimated unit thrust vector
is not needed and not computed.
<br />
<br />
If either<br />
<ol>
<li>guidance provides a unit window command too
closely alined with the unit thrust command to
adequately determine the attitude orientation about
the XCB-axis, or</li>
<li>the guidance program is P66 (which provides no
unit window command), </li>
</ol>
<br />
then ATT provides a unit window command suitable for
erection of the commanded-body frame and resets a flag to
indicate that no attitude rotation is allowed about the
XCB-axis. ATT first provides the current ZB-axis (Eq.
(15.8)). But this choice may also be nearly collinear with
the unit thrust command, so a second possibility, the
current negative XB-axis, is also offered (Eq. (15.9)).
Because the ZB- and XB-axes cannot both parallel the unit
thrust command, no further checks need be made.
<br />
<br />
The matrix <span style="color: blue;"><i>CCBP</i></span>, whose row vectors are the commanded-body
frame unit vectors expressed in platform coordinates, is
computed to satisfy the unit thrust command, the unit window
command, and the thrust offset (the angular displacement
between the estimated unit thrust vector and the XRB-axis).
<span style="color: blue;"><i>CCBP</i></span> is computed in two steps as illustrated in Figure 16.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvz7ltcJRRRkSEeiq4h0LCFJ_wjALtNRf3oP5rx6mxnkkaDTirACw1yVLD9cPdfTamQ3OlAVin4jLJWNe8fWkPN9nVCiafdhTVvxFZa70JrOALoQKQz-T3q-Rou03wTtqgbDct8fvUPBwv/s1600/Fig_16_LM_Centered_Unit_Sphere.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="381" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgvz7ltcJRRRkSEeiq4h0LCFJ_wjALtNRf3oP5rx6mxnkkaDTirACw1yVLD9cPdfTamQ3OlAVin4jLJWNe8fWkPN9nVCiafdhTVvxFZa70JrOALoQKQz-T3q-Rou03wTtqgbDct8fvUPBwv/s400/Fig_16_LM_Centered_Unit_Sphere.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 16. Geometry of Erection of Commanded-body Frame Viewed on a LM-centered Unit Sphere.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The first step (Eqs. (15.10) - (15.12)) uses the unit thrust
command and the unit window command but fails to account for
thrust offset. The second step (Eqs. (15.13) - (15.15))
corrects for thrust-offset components <span style="color: blue;"><i>UNFRBy</i></span> and <span style="color: blue;"><i>UNFRBz</i></span>.
Since these corrections are small, no unit need be taken in
Eq. (15.14). A small window pointing error, shown in Figure
16, is introduced by the thrust-offset correction. Defined
as the angle between the ZCB, XCB plane and the unit window
command, the window pointing error is the product of the
sine of the LPD angle and the thrust-offset angle about the
ZCB-axis. Although the trim gimbal has a maximum
displacement of 6°, the maximum thrust offset during descent
is about 1°, which yields a maximum window pointing error of
0° at 0° LPD angle and 0.9° at 65° LPD angle, the lower edge
of the LM window.
<br />
<br />
Because the matrix <span style="color: blue;"><i>CCBP</i></span> is the transformation from platform
to commanded body coordinates, it can be expressed in terms
of the IMU gimbal angles which would place the body axes in
the commanded directions. Therefore, commanded gimbal angles
can be extracted from the commanded-body matrix. Expressing
<span style="color: blue;"><i>CCBP</i></span> as the product of the three matrices that correspond to
rotations about the three gimbal axes yields
<br />
<br />
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<br />
<br />
where <span style="color: blue;"><i>S</i></span> and <span style="color: blue;"><i>C</i></span> indicate sine and cosine, and <span style="color: blue;"><i>X</i></span>, <span style="color: blue;"><i>Y</i></span>, and <span style="color: blue;"><i>Z</i></span>
indicate the commanded X, Y, and Z gimbal angles. From Eq.
(13), it is apparent that the commanded gimbal angles are
extracted from the elements of <span style="color: blue;"><i>CCBP</i></span> by Eqs. (15.16) -
(15.18), with <b><i>ARCTRIG</i></b> defined as follows.
<br />
<br />
The ARCTHIG function of two arguments yields the angle whose
tangent is the ratio of the first and second arguments.
ARCTRIG extracts the angle anywhere in the circle by using
the ratio of the smaller-magnitude argument to the larger
magnitude argument as the tangent of the angle or its
complement, and by using the signs of the arguments to
determine the quadrant of the angle. Equations (15.16) and
(15.17) yield the outer and inner commanded gimbal angles
anywhere in the circle. Because the second argument is
always positive, implying a positive cosine, Eq. (15.18)
yields the middle commanded gimbal angle between ±90°.
<br />
<br />
<u>To preclude commanding gimbal lock</u>, Eq. (15.20) limits the
middle commanded gimbal angle to 70° magnitude. Because the
unlimited value lay between ±90° and the outer and inner
commanded gimbal angles were computed consistent with the
middle commanded gimbal angle range, no quadrant switching
of the outer or inner commands is required by gimbal-lock
limiting. If limiting charges the middle command, the
guidance is commanding gimbal lock, and the gimbal-lock
alarm code is issued.
<br />
<br />
Unlimited reference gimbal angle changes are the changes
which would be required to bring the DAP's reference gimbal
angles into coincidence with the commanded gimbal angles.
These are computed by subtracting, modularly, the current
reference gimbal angles from the commanded gimbal angles
(Eq. (15.21)). The modular subtractions yield the smaller
angular differences, i.e.,
<br />
<br />
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<br />
If a Y or Z gimbal angle change greater than 45° is
required, the flag is reset indicating no attitude rotation
is allowed about the XCB-axis. This is necessary to prevent
false starts about the XCB-axis as derived in the appendix
of reference /12/.
<br />
<br />
Equations (15.24) - (15.28) yield the reference gimbal angle
changes by limiting the magnitude of the attitude changes to
20° in 2 seconds (10°/sec) about each of three orthogonal
axes; one axis is coincident with the XCB-axis and the other
axes lie in the YCB, ZCB plane. This permits an angular-rate
vector of length <b><i>Sqrt(3*10^2)</i></b> deg/sec. Note that if the flag is reset,
the attitude rotation about the XCB-axis is made zero,
resulting in an outer gimbal angle change to offset the
inner gimbal angle change (Eq. (15.28)).
<br />
<br />
The DAP commands consist of the reference gimbal angle
increments to be applied by the DAP each 1/10 second, the
reference attitude rates, and the permitted lag angles. The
reference gimbal angle increments are the reference gimbal
angle changes multiplied by the ratio of the DAP and ATT
sample intervals (Eq. (15.29)). The reference attitude rates
are computed by the non orthogonal transformation of the
reference gimbal angle changes shown in Eq. (15.30). The
permitted lag angles, which account for the angles by which
the attitude will lag behind a ramp angular command due to
the finite accelerations available, are computed using the
available acceleration <span style="color: blue;"><i>alpha_vec_RB</i></span>, and then individually
magnitude limited (Eq. (15.31)). The DAP avoids
attitude-rate overshoot by permitting lagging attitude
errors equal to the permitted lag angles."
<br />
<br />
<br />
<br />
<h4>
THROTTLE ROUTINE
</h4>
<br />
"The throttle routine connects the currently operating
guidance algorithm to the DPS, as illustrated in Figure 17.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGH_aGnV2TGIxlJ_Ddr3gNHsTIP_IXG3I8VxJ17ZuhC0TWdOi16cwC9tEZpE4zhQzSOEYCTb3fZUpUwiU8V2ePmlo2j8ZiUbUInKyNANiLiAaa7TO1Tf_JBgPLdfkyZD7FHUpAMUpvfn9_/s1600/Fig_17_DPS_Thrust_Control.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="336" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGH_aGnV2TGIxlJ_Ddr3gNHsTIP_IXG3I8VxJ17ZuhC0TWdOi16cwC9tEZpE4zhQzSOEYCTb3fZUpUwiU8V2ePmlo2j8ZiUbUInKyNANiLiAaa7TO1Tf_JBgPLdfkyZD7FHUpAMUpvfn9_/s400/Fig_17_DPS_Thrust_Control.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 17. DPS Thrust Control Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
For ease of understanding, all thrust levels are represented
as percentages of the DPS rated thrust of 46,706 newtons.
<i><b>THROT</b></i> generates thrust increment commands to drive the input
thrust-acceleration measurement into coincidence with the
input thrust- acceleration command whenever the resulting
thrust would lie within the illustrated permitted-thrust
region. When the resulting thrust would lie below or above
the permitted-thrust region, THROT causes minimum or maximum
thrust. The hysteresis-like region from 57 to 65% thrust
avoids frequent alternation between the maximum-thrust point
and the permitted-thrust region when the thrust command
dwells at the boundary between the permitted-thrust and
forbidden-thrust regions.
<br />
<br />
A digital-to-analog interface between the LGC and the DPS is
provided by the descent engine control assembly (DECA). Each
guidance cycle (once per two seconds, except once per second
for P66) THROT generates the thrust increment command
delta_FC% which is converted to a pulse train and issued to
the DECA. Each pulse causes about 12.5 newtons thrust
change, and the pulse rate is 3,200/second. Following
issuance of a thrust increment command, the thrust therefore
changes at the rate of 40,000 newtons/second (85% of rated
thrust per second) until the thrust increment is achieved.
With a guidance cycle as short as one second and an engine
response time which may be a substantial fraction of one
second, it is necessary for P66 and THROT to account for
this transport delay.
<br />
<br />
As illustrated in the rightmost box of Figure 17, in the
region from 11 to 93% the DPS thrust is a nearly linear
function of the pulse count accumulated by the DECA. Not
shown in Figure 17 is the manual throttle command, which is
summed with the DECA output command by the DPS and provides
the minimum 11% thrust when the DECA command is zero. The
DPS contains a mechanical stop at typically 93% rated
thrust. This thrust level minimizes propellant consumption
on a nominal descent, considering the loss of specific
impulse at higher thrust. To ensure that the DPS is driven
to the mechanical stop, the DECA saturates at a
substantially higher thrust level (about 99%) and the
throttle routine drives the DECA into saturation whenever
maximum thrust is required.
<br />
<br />
Non linearities in response and uncertainties in DECA and
DPS scale factors are overcome by the thrust increment
command concept. Nominally, THROT provides dead-beat
response to step inputs, but with downstream non linearities
and scale-factor errors THROT drives the thrust-acceleration
error to zero in the steady state.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyNxEYzuFhVkVHtzC3U_qAEwHPgHBqRS_Yo5j_0sju8_kUUkvEN_yvx1ptxHbDJSvandnqJDJlLZg8FSrJIHTjM65WNloPBFq0lo3OswVHkXeKMG_V9WKw5rvQ9A0c1BLZ8OrORcO1Et87/s1600/Fig_18_Throttle_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhyNxEYzuFhVkVHtzC3U_qAEwHPgHBqRS_Yo5j_0sju8_kUUkvEN_yvx1ptxHbDJSvandnqJDJlLZg8FSrJIHTjM65WNloPBFq0lo3OswVHkXeKMG_V9WKw5rvQ9A0c1BLZ8OrORcO1Et87/s400/Fig_18_Throttle_Block_Diagram.png" width="226" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 18. Throttle Routine Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 18 illustrates the Throttle Routine computations. The
thrust command and thrust measurement are computed using the
input mass estimate (Eqs. (18.1) - (18.2)). The input
thrust-acceleration measurement is the average over the
preceding sample interval, during which a thrust increment
command was issued producing an instantaneous thrust profile
as illustrated in Figure 19.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0q5v6VNsO0vN-oi1BJDc-ocCirOzOarHkCJPZFgoK3QOvH_26NtrAXwaODUg94bMBHGh372FCo7syuavEClNhvYzaIer7wi08hSQK2nlrxVZpsWlBeQSZAKEHsWkg1xJxpos3YFTEM7c3/s1600/Fig_19_Single_Guidance_Sample.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="248" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0q5v6VNsO0vN-oi1BJDc-ocCirOzOarHkCJPZFgoK3QOvH_26NtrAXwaODUg94bMBHGh372FCo7syuavEClNhvYzaIer7wi08hSQK2nlrxVZpsWlBeQSZAKEHsWkg1xJxpos3YFTEM7c3/s400/Fig_19_Single_Guidance_Sample.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 19. Thrust Dynamics within a Single Guidance Sample Interval.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Therefore, to obtain the
current sample-instant thrust, Eq. (18.3) corrects the
thrust measurement by adding the thrust correction increment
computed the previous cycle.
<br />
<br />
The thrust-control logic for providing the required overall
system response illustrated in Figure 17 is to pick one of
four possible thrusting policies according to the regions of
the preceding and present thrust commands (<span style="color: blue;"><i>FCOLD%</i></span> and <span style="color: blue;"><i>FC%</i></span>),
and to reset the thrust command if necessary to satisfy DPS
constraints. Equation (18.4) or (18.8) resets the thrust
command to the thrust actually anticipated. A thrust command
augment (<span style="color: blue;"><i>FC_AUG%</i></span>) is computed that either drives the DECA
into saturation if the policy is to initiate or retain
maximum thrust (Eq. (18.5) or (18.9)), or corrects for the
region between the DPS mechanical stop and the DECA
saturation value if the policy is to initiate thrusting
within the permitted-thrust region (Eq. (18.7)). No thrust
command augment is required when the policy is to continue
thrusting within the permitted-thrust region. No equivalent
thrust-control logic is needed at the minimum-thrust point
because minimum thrust would occur only if the commander
could issue five or more downward ROD commands within a
single P66 guidance sample interval, practically impossible.
<br />
<br />
The thrust increment command (Eq. (18.12)) is composed of
the actual thrust increment <span style="color: blue;"><i>delta_FA%</i></span>, plus the thrust
command augment <span style="color: blue;"><i>FC_AUG%</i></span> to drive the DECA in or out of
saturation, when required.
<br />
<br />
Preparatory to computing the thrust correction increment for
the succeeding pass, Eq. (18.13) computes the total
effective transport lag. The terms in the effective
transport lag are<br />
<ol>
<li>the computation duration <span style="color: blue;"><i>t - tSI</i></span>,</li>
<li>the estimated DPS time constant of 0.08 second,
and</li>
<li>the effective DECA delay equal to half the time
required to output the thrust increment command
pulse train at 85% thrust change per second.
</li>
</ol>
<br />
As long as the actual thrust increment <span style="color: blue;"><i>delta_FA</i></span> (Figure 19)
is contained entirely within the sample interval <span style="color: blue;"><i>delta_t</i></span>, it
is clear that, as <span style="color: blue;"><i>LAG</i></span> approaches zero, the thrust
measurement (obtained by differencing accelerometer readings
at the sample instants) approaches the sample-instant thrust
<span style="color: blue;"><i>F</i></span>. Similarly, as <span style="color: blue;"><i>LAG</i></span> approaches the sample interval <span style="color: blue;"><i>delta_t</i></span>,
the thrust measurement must be augmented by an amount
approaching the actual thrust increment <span style="color: blue;"><i>delta_FA</i></span> to obtain
the sample-instant thrust <span style="color: blue;"><i>F</i></span>. From this heuristic argument,
it is apparent that the thrust correction increment which
must be added to the thrust measurement to yield the
sample-instant thrust is proportional to <span style="color: blue;"><i>LAG</i></span> as computed by
Eq. (18.14). A rigorous derivation of this result is
presented in Appendix A of reference /11/. The sole purpose
of Eq. (18.15) is to interface the P66 Vertical (ROD)
Guidance Algorithm.
<br />
<br />
With the thrust command <span style="color: blue;"><i>FC%</i></span> either within the
permitted-thrust region or reset to the value which will
actually be achieved, <span style="color: blue;"><i>delta_FA%</i></span> is an accurate prediction of
the actual thrust increment, and <span style="color: blue;"><i>sigma_FA%</i></span> or <span style="color: blue;"><i>sigma_FA</i></span> is an
accurate thrust correction increment, <span style="color: blue;"><i>sigma_FA%</i></span> or <span style="color: blue;"><i>sigma_FA</i></span>
is slightly in error when initiating thrusting within the
permitted-thrust region. The slight error is due to
neglecting <span style="color: blue;"><i>FC_AUG%</i></span> in the computation of <span style="color: blue;"><i>LAG</i></span>."
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_M1-DwzNFVrWz-xb2xNuBcvZmWNBLdLK7CoC0VD5zsu1FDoTBQUEGQolTFKfl0Dxin64LqD5et3KQpyqrZEIqJhH7_gePXV_9gxo3U1bf-voKd2G6TsAKXWT8E4W-OTo3hIkCn7shE5UL/s1600/s69-34038.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="261" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_M1-DwzNFVrWz-xb2xNuBcvZmWNBLdLK7CoC0VD5zsu1FDoTBQUEGQolTFKfl0Dxin64LqD5et3KQpyqrZEIqJhH7_gePXV_9gxo3U1bf-voKd2G6TsAKXWT8E4W-OTo3hIkCn7shE5UL/s400/s69-34038.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">S69-34038 (18 May 1969) <br />View of activity at the flight director's console in the Mission Operations Control Room in the Mission Control Center, Building 30, on the first day of the Apollo 10 lunar orbit mission. Seated are Gerald D. Griffin (foreground) and Glynn S. Lunney, Shift 1 (Black Team) flight directors. Milton L. Windler, standing behind them, is the flight director of Shift 2 (Maroon Team). In the center background, standing, is Dr. Christopher C. Kraft Jr., MSC Director of Flight Operations.<br /></span></i></span></td></tr>
</tbody></table>
<br />
<br />
<h4>
BRAKING-PHASE AND APPROACH-PHASE TARGETING PROGRAM
</h4>
<br />
"The targeting program generates mission-dependent data for
the P63 Ignition Algorithm and for the P63, P64 Guidance
Algorithm. All data are expressed in guidance coordinates.
The ignition algorithm requires nominal initial altitude,
range, and speed data that determine ignition time and
indirectly determine the throttle control duration. The
guidance algorithm requires targets for P63 that provide an
efficient transfer and targets for P64 that provide a
trajectory meeting several constraints on geometry,
visibility, and thrust. Described in detail in reference 5,
the P64 constraints provide a fast shallow approach phase
more akin to an airplane approach than a helicopter
approach, although the terminal-descent phase is essentially
vertical in helicopter fashion. The landing site must be
approached along a nearly straight-line path depressed
typically 16° from horizontal, terminating typically at 30 m
altitude ii m ground range. The landing site must be visible
continuously until a few seconds before approach-phase
terminus, and the DPS thrust must begin at around 57% and
must lie continuously in the 11 to 65% region.
<br />
<br />
Geometry, visibility, and thrust during approach cannot be
specified explicitly. Visibility depends upon the position
and attitude profiles, and these profiles (with the thrust
and mass profiles) are constrained to satisfy the laws of
physics. The guidance algorithm will provide the transfer
from any arbitrary initial state (within bounds) without
regard to any visibility or thrust constraints. The task of
the targeting program is to set up the P64 initial state and
guidance targets such that suitable visibility and thrust
profiles are realized implicitly.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXXGUT6hE2Zpiqn2LasPtuYjZ_SeF2Tqjl2KxMOOj-9iMb9-g5paEnO19_QuaFyZa0DnSL7RVnPwmTVTtvYZSb-BlLwo4I7UEFe0774Ztypcft66FXEtHEfxLoeVLAtbzxJV2Lj6Huytjb/s1600/Fig_20_Composition_of_the_Lunar-descent_Trajectory.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjXXGUT6hE2Zpiqn2LasPtuYjZ_SeF2Tqjl2KxMOOj-9iMb9-g5paEnO19_QuaFyZa0DnSL7RVnPwmTVTtvYZSb-BlLwo4I7UEFe0774Ztypcft66FXEtHEfxLoeVLAtbzxJV2Lj6Huytjb/s400/Fig_20_Composition_of_the_Lunar-descent_Trajectory.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 20. Composition of the Lunar-descent Trajectory.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
During the final portion of P63, and throughout P64, the
guidance algorithm will generate a trajectory whose position
vector is a quartic polynomial function of time, as shown in
Figure 20. Targeting consists of<br />
<ol>
<li>defining each of the two polynomials and</li>
<li>extracting the guidance targets as the position
vector and its derivatives at a target point, lying
on the polynomial, substantially beyond phase
terminus.
</li>
</ol>
<br />
The P64 targeting concept is to construct the
approach-phase quartic by imposing necessary and sufficient
constraints. With quartic degree, five independent
constraints may be imposed in each of three axes. The
nominal trajectory is arbitrarily made planar, requiring the
Y-components in guidance coordinates of position and all its
derivatives to be zero and leaving two axes to specify.
Because the initial state can be controlled by the preceding
braking-phase guidance, all five constraints in each of the
two remaining axes may be specified arbitrarily. Since these
ten constraints - called a P64 constraint set - completely
determine the P64 trajectory, the geometry and visibility
profiles can be determined in closed form, and the thrust
profile can be determined from a prior knowledge of mass.
Thus P64 targeting consists of generating closed-form
solutions for a number of P64 constraint sets and picking
one which provides adequate visibility and thrust.
Specification of P64 constraint sets is reduced to a
two-dimensional search, as will be described in the
following section.
<br />
<br />
The P63 targeting process is not so clean. Because the
engine must be run at fixed maximum thrust for most of the
phase, the guidance commands are not satisfied, and
therefore, as shown in Figure 20, the maximum-thrust portion
of P63 is not quartic. When throttle control is recovered,
generation of a quartic is begun. But the throttle recovery
point is not close to any target point. Therefore the state
vector at this point cannot be controlled, and we have no
closed-form solution for it. Since the initial position and
velocity on the braking-phase quartic must be free, there
remain only three constraints, in each of two axes, which
can be imposed arbitrarily. The guidance algorithm permits a
fourth constraint in one axis by solving for the current
target-referenced time such as to satisfy a constraint on
the ZG-component of jerk. Thus a P63 constraint set composed
of seven constraints is specified arbitrarily, and the
remaining three conditions required to define the
braking-phase quartic are determined iteratively by
simulation. Three or four iterations are generally required
because there is bilateral interaction between the targets
and the simulation."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Constraints
</b></span><br />
<br />
"The P64 constraint set is constructed as follows:
<br />
<br />
1. Four constraints at a specified target-referenced
terminal time TAPF: Two terminal vertical
constraints, specified by the mission commander, are
the terminal altitude (<span style="color: blue;"><i>RAPFGx</i></span> = 30-m typically) and
altitude rate (<span style="color: blue;"><i>VAPFx</i></span> = -l-m/sec typically). Two
terminal horizontal constraints, imposed by the
choice of effective P66 horizontal time constant
tau, are that the terminal position, velocity, and
acceleration shall be related by
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6jIb3CMDfogfxy6DB6JsnJjUsP537PF39HF57uKltRiPFKVZIgDOVDmEUwLhTXcdJZRk6dom66TAde4NNlshEI-gsqdgmNVe10ouURacOJllCKjhHGpC4rT0Zt8KROKIRc2w6XW9qoe_o/s1600/eq_71_72.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="52" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6jIb3CMDfogfxy6DB6JsnJjUsP537PF39HF57uKltRiPFKVZIgDOVDmEUwLhTXcdJZRk6dom66TAde4NNlshEI-gsqdgmNVe10ouURacOJllCKjhHGpC4rT0Zt8KROKIRc2w6XW9qoe_o/s320/eq_71_72.png" width="320" /></a></div>
<br />
These P66 compatibility constraints cause the pitch
commands at P64 terminus and P66 inception to be
identical (avoiding a pitch transient at the phasic
interface) and cause the P66 algorithm to null the
horizontal position error as well as the horizontal
velocity error, without position feedback. Because
the P66 horizontal algorithm feeds back the prior
acceleration command, and because of the transport
delay, an effective tau of 8 seconds has been found
satisfactory rather than the 5 seconds used by the
P66 algorithm.
<br />
<br />
2. Four constraints at an unspecified
target-referenced midpoint time <span style="color: blue;"><i>TAPM</i></span>: The midpoint
constraints are specified by the commander according
to his sense of safety and comparability with a
possible manual transition to P66. Typically, he may
specify -5-m/sec altitude rate at 150-m altitude,
and a 16° slope, completely determining the midpoint
state <span style="color: blue;"><i>R_APMG</i></span>, <span style="color: blue;"><i>V_APMG</i></span> given<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhI5CIAIUP6ihkX11kP7xw_3mbd1VrvheC-bXlGLfLnzEBLxExfUD_cFVXOpRZBLtIe7OszlE72jOej_Jth96uMsZK7i9ya3lzoONpuPXgH8NKGVgRbivSZjiB9KSskGhlCo-fPMw8Xt0uK/s1600/eq_73.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="20" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhI5CIAIUP6ihkX11kP7xw_3mbd1VrvheC-bXlGLfLnzEBLxExfUD_cFVXOpRZBLtIe7OszlE72jOej_Jth96uMsZK7i9ya3lzoONpuPXgH8NKGVgRbivSZjiB9KSskGhlCo-fPMw8Xt0uK/s320/eq_73.png" width="320" /></a></div>
<br />
3. Two constraints at an unspecified
target-referenced initial time <span style="color: blue;"><i>TAPI</i></span>: The initial
position is arbitrarily specified to lie on the 16°
path and to provide an approach phase of typically
7.5-kin length, determining the initial position
vector <span style="color: blue;"><i>R__APIG</i></span> given<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWs_KgDZMjaQS-h5uO5JZJHfLwSF57G7hClOIOlfLSxY9_PrD__JS-3g_Ebc6ZcX6HJvwVL7E2NoUoj8Qm6kuBsA7ByuymgS5WyrU6_F2fG8dOnpRFcLHqCVirkHVpV817TWS7h2T9EjSi/s1600/eq_74.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="26" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWs_KgDZMjaQS-h5uO5JZJHfLwSF57G7hClOIOlfLSxY9_PrD__JS-3g_Ebc6ZcX6HJvwVL7E2NoUoj8Qm6kuBsA7ByuymgS5WyrU6_F2fG8dOnpRFcLHqCVirkHVpV817TWS7h2T9EjSi/s320/eq_74.png" width="320" /></a></div>
<br />
This completes the P64 constraint set except for specifying
the times <span style="color: blue;"><i>TAPM</i></span> and <span style="color: blue;"><i>TAPI</i></span> at which the midpoint and initial
constraints apply. These times are determined by running the
Approach-phase Targeting Routine over the two-dimensional
sweep of values of <span style="color: blue;"><i>TAPM</i></span> and <span style="color: blue;"><i>TAPI</i></span>. From the cases run, one is
picked that exhibits suitable attitude and thrust behavior
(based on an a-priori P64 initial mass estimate). If
subsequent simulation proves the mass estimate excessively
in error, the initial thrust will be unsatisfactory, and an
alternate case must be picked.
<br />
<br />
The seven P63 constraints are specified as follows: Four
constraints are specified by compatibility of the terminal
state on the braking-phase quartic with the initial state on
the approach-phase quartic. Two constraints are imposed on
terminal acceleration by requiring the terminal thrust to be
57% and by specifying the terminal pitch angle. The final
constraint is imposed on the horizontal component of
terminal jerk by requiring zero rate of change of thrust at
terminus. The terminal pitch angle, typically around 60°, is
chosen by trial and error to minimize propellant
consumption."
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiy5z-vxSoswFnnXoaxGLEfpWtDnZFLPAIU_J9UadaT9aKRbFxlHuthdiNM49QPo-nuQPXVWRYaH57m7j7-l6ROwd9XrLbUj2gbFEhT3K9VODfqkMy-L3hIQI_Tz-TKHDpLYawTRg3xEFOS/s1600/AGC_interconnetions_.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiy5z-vxSoswFnnXoaxGLEfpWtDnZFLPAIU_J9UadaT9aKRbFxlHuthdiNM49QPo-nuQPXVWRYaH57m7j7-l6ROwd9XrLbUj2gbFEhT3K9VODfqkMy-L3hIQI_Tz-TKHDpLYawTRg3xEFOS/s400/AGC_interconnetions_.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 61. LGC computer upside down showing the wire wrap connections area which actually built up the computer's logic units when connecting the discrete logic component modules facing down.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #0c343d;"><b>Approach-phase Targeting
</b></span><br />
<br />
"Figure 21 illustrates the Approach-phase Targeting Routine.<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgovhm0Mf5VS4KmaKZo0do2ZOQOp489wGEOTeNWA42d8IP76dVBJuEBs9wBEQQ3uJJDB2KYMnekcdiEHaRRIm7f1mL3geFY1GwFr5XDuXNX6FtmKe1lL5tINy-H1-KNK5nq0lW1FsPJKBlZ/s1600/Fig_21_Approach-phase_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgovhm0Mf5VS4KmaKZo0do2ZOQOp489wGEOTeNWA42d8IP76dVBJuEBs9wBEQQ3uJJDB2KYMnekcdiEHaRRIm7f1mL3geFY1GwFr5XDuXNX6FtmKe1lL5tINy-H1-KNK5nq0lW1FsPJKBlZ/s400/Fig_21_Approach-phase_Block_Diagram.png" width="227" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 21. Approach-phase Targeting Routine Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
Normally, this routine is first run separately in search of
targets for the approach phase, and then run jointly with
the Braking-phase Targeting Routine (Figure 22) to determine
targets for the entire lunar descent.<br />
<br />
In the XG-axis (altitude), the terminal acceleration, jerk,
and snap are computed by Eq. (21.2), which is obtained
immediately from<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo6YuR5Tqf_0C208mQpdV0XkgZsTOvM848EnvvfOdq3KOYRnSSTVqhLEVJsgSkQRuw-wBeB-Ombo8W7wfQcVIUSgm0mPB8vxD_Ab4tQfH47jb-Sz3csgHvPPyBOTCGPa9_2va7gUHqI5BK/s1600/eq_14.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="75" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo6YuR5Tqf_0C208mQpdV0XkgZsTOvM848EnvvfOdq3KOYRnSSTVqhLEVJsgSkQRuw-wBeB-Ombo8W7wfQcVIUSgm0mPB8vxD_Ab4tQfH47jb-Sz3csgHvPPyBOTCGPa9_2va7gUHqI5BK/s400/eq_14.png" width="400" /></a></div>
<br />
where <span style="color: blue;"><i>TMF</i></span> and <span style="color: blue;"><i>TIF</i></span> are the midpoint and initial
terminus-referenced times computed by Eqs. (21. 1).
<br />
<br />
In the YG-axis, position and all its derivatives are zero to
produce a planar trajectory.
<br />
<br />
In the ZG-axis, Eq. (21.4) is obtained by substituting the
P66 compatibility constraints
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6jIb3CMDfogfxy6DB6JsnJjUsP537PF39HF57uKltRiPFKVZIgDOVDmEUwLhTXcdJZRk6dom66TAde4NNlshEI-gsqdgmNVe10ouURacOJllCKjhHGpC4rT0Zt8KROKIRc2w6XW9qoe_o/s1600/eq_71_72.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="52" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6jIb3CMDfogfxy6DB6JsnJjUsP537PF39HF57uKltRiPFKVZIgDOVDmEUwLhTXcdJZRk6dom66TAde4NNlshEI-gsqdgmNVe10ouURacOJllCKjhHGpC4rT0Zt8KROKIRc2w6XW9qoe_o/s320/eq_71_72.png" width="320" /></a></div>
<br />
into the ZG-axis version of Eq. (14) and inverting.
Equations (21.5) and (21.6) complete the definition of the
approach-phase quartic. It remains to compute the
approach-phase targets as the position vector and its
derivatives at the target point on the quartic.
<br />
<br />
For a quartic polynomial, a 5 x 5 state transition matrix
<span style="color: blue;"><i>Phi</i></span>(<span style="color: blue;"><i>T1</i></span>, <span style="color: blue;"><i>T0</i></span>) can be defined by
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHVKYpxT8921trPw4SQc-28RVMjdzJlbpl-4NhAGJLsENZyadSW3_9Y2qvVjCsERl_jf6qOsQ6dKP3Q-YhGZkpBWNUYSzyL2AthlviVQXhbT8PJ-FpwLiqTXFMOfkSDoFwaF_GGz6QFjeD/s1600/eq_75.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="136" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHVKYpxT8921trPw4SQc-28RVMjdzJlbpl-4NhAGJLsENZyadSW3_9Y2qvVjCsERl_jf6qOsQ6dKP3Q-YhGZkpBWNUYSzyL2AthlviVQXhbT8PJ-FpwLiqTXFMOfkSDoFwaF_GGz6QFjeD/s400/eq_75.png" width="400" /></a></div>
<br />
where <span style="color: blue;"><i>R_i</i></span> to <span style="color: blue;"><i>S_i</i></span> are row vectors. <span style="color: blue;"><i>Phi(T1, T0)</i></span> can be derived
using linear systems theory,
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-WKC8NuAtEqAOgxlOI5EO_m4yadowYOUrM6wCrCkZePs9zqXpt97XgmNc7DXxz9m3aO05ujlBQLfXb4Ps1wGv1Cg_ocflBxPctJxkC1YTgFcY_Dn9BpwNsPyMBXYNDGdsvSkYXZlejv4A/s1600/eq_76.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="96" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-WKC8NuAtEqAOgxlOI5EO_m4yadowYOUrM6wCrCkZePs9zqXpt97XgmNc7DXxz9m3aO05ujlBQLfXb4Ps1wGv1Cg_ocflBxPctJxkC1YTgFcY_Dn9BpwNsPyMBXYNDGdsvSkYXZlejv4A/s320/eq_76.png" width="320" /></a></div>
<br />
with the solution
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQhbHvEwuni536uBx2IUqzfmy1ofAAFPXhnukS1LtAS3n2i-iOgtSwjBI4yo7kXcu6IJgleM-bG1FJchNv2BAFi9M2bIk2aSNVp5B72xybwUmZ5hB9RS_afkuXmSgFVsGXwCgWpLOml_mC/s1600/eq_77.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="136" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQhbHvEwuni536uBx2IUqzfmy1ofAAFPXhnukS1LtAS3n2i-iOgtSwjBI4yo7kXcu6IJgleM-bG1FJchNv2BAFi9M2bIk2aSNVp5B72xybwUmZ5hB9RS_afkuXmSgFVsGXwCgWpLOml_mC/s320/eq_77.png" width="320" /></a></div>
<br />
where <span style="color: blue;"><i>I</i></span> is the 5 × 5 identity matrix. The exponential series
is zero after the fifth term because <span style="color: blue;"><i>alpha_i</i></span> = 0 for <span style="color: blue;"><i>i</i></span> › 5.
All the properties of state transition matrices can be
applied to scalar and vector polynomials.
<br />
<br />
Equations (21.7) yield the complete target and initial
states by using state transition matrices and the definition
of target-referenced target time as zero."
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwdVpzVd-DLWeD_x7T1MNOmXEXdN8IwF2YbhFysFMsSbvxpLWgt-1b546ZjFDKIlvHhBALa1YJ6qQEyNk6st-TPe9mDjIAE0oz4SvLNqzngF_buLcm6r3MlmRjIfNLPdPaHyBz1T26ZyBE/s1600/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwdVpzVd-DLWeD_x7T1MNOmXEXdN8IwF2YbhFysFMsSbvxpLWgt-1b546ZjFDKIlvHhBALa1YJ6qQEyNk6st-TPe9mDjIAE0oz4SvLNqzngF_buLcm6r3MlmRjIfNLPdPaHyBz1T26ZyBE/s400/NV_0905_Driscoll_apollo_guidance_computer_block_2_display_and_keyboard.1966.jpg" width="385" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 62. DSKY (Display and Keyboard) was a vital part of the computer used to communicate with the human operator (astronaut) ... actually the LGC was connected to almost all switches and display devices in the LM cockpit additional to DSKY (so there was almost "no life" without the computer already 1960's)</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>Braking-phase Targeting
</b></span><br />
<br />
"To target P63, we must completely determine the
braking-phase quartic shown in Figure 20. Seven of the ten
necessary conditions are determined in closed form, although
three are based on a P63 terminal mass estimate which must
be updated by simulation. The remaining three conditions
necessary to define the quartic are determined iteratively
by simulation. The terminal pitch angle <span style="color: blue;"><i>theta_PBRF</i></span> is a
fixed input to the Braking-phase Targeting Routine.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipeoHfiQWjAFNFzRjWy4xkDuWazKTHPXYzEgUM-IEOQekvTc0G5mOgXD42v_wVVv76hBv71v4kuSA-fPsHfm_w7d9Qz8YVc4SFaeIPFHaE8XaoOVL-AOEW61_GYsWbvkjUzL4lGIw3_wsa/s1600/Fig_22_Braking-phase_Block_Diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipeoHfiQWjAFNFzRjWy4xkDuWazKTHPXYzEgUM-IEOQekvTc0G5mOgXD42v_wVVv76hBv71v4kuSA-fPsHfm_w7d9Qz8YVc4SFaeIPFHaE8XaoOVL-AOEW61_GYsWbvkjUzL4lGIw3_wsa/s400/Fig_22_Braking-phase_Block_Diagram.png" width="151" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 22. Braking-phase Targeting Routine Block Diagram.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 22 illustrates the routine. Four conditions are
specified by setting the P63 terminal position and velocity
equal to the P63 initial state* (Eqs. (22.1)). <span style="color: #274e13;"><i>[*Not shown is the capability of the targeting program to
set the P63 terminal state to a backwards extrapolation of
the P64 initial state to allow for a short transition during
which the acceleration is assumed to change linearly with
time. This capability is not always used, and to show it
would unnecessarily complicate the presentation of Figure
22.]</i></span> A unit vector
in the terminal-thrust direction is computed from the
terminal pitch angle <span style="color: blue;"><i>theta_PBRF</i></span> (Eq. (22.2)), and the
terminal acceleration is calculated by Eq. (22.3) using the
terminal thrust <span style="color: blue;"><i>FBRF</i></span>, the P63 terminal mass estimate <span style="color: blue;"><i>MBRF</i></span>,
and allowing for lunar gravity <span style="color: blue;"><i>GM</i></span>. The XG-component of
terminal jerk must be determined by simulation and is
therefore set to zero for the first iteration (Eq. (22.5)).
The ZG-component of terminal jerk is computed by Eq. (22.5)
to produce zero rate of change of thrust at terminus,
accounting for the estimated terminal mass flow rate
computed by Eq. (22.4); the jerk coefficient <span style="color: blue;"><i>KJ</i></span>, typically
1.2, accounts for the XG-component of thrust. The terminal
snap must be determined by simulation and is therefore set
to zero (Eq. (22.6)) for the first iteration. This completes
the first-iteration definition of the braking-phase quartic.
<br />
<br />
<br />
Braking-phase targets are computed by Eq. (22.7), using the
state transition matrix and the definition of
target-referenced target time as zero. Using the computed
targets, a simulation is run to produce corrected data.
<br />
<br />
The nominal initial range used by the ignition algorithm is
corrected by Eq. (22.8) to correct the error in the target-
referenced time of throttle control recovery.
<br />
<br />
The simulation produces a braking-phase quartic satisfying
the target values of position, velocity, acceleration, and
ZG-component of jerk. The remaining conditions necessary to
define the quartic can be obtained from the current state on
the last pass of the braking-phase simulation. The equation
for the current state,
<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEmHmCxdtLjDgqe3Cf52ifmhBjK-D5MEo_LzJ3mCXo9dlWhGj9tVyo6tgECOe4w6Dk-h1UNq7nv6Jf7UaM0-4wZRzkKPg-2cdQQBwashG6D1ySyadZSADf2MRuS5bOSTAUR9_mRF6GacVw/s1600/eq_78.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="87" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEmHmCxdtLjDgqe3Cf52ifmhBjK-D5MEo_LzJ3mCXo9dlWhGj9tVyo6tgECOe4w6Dk-h1UNq7nv6Jf7UaM0-4wZRzkKPg-2cdQQBwashG6D1ySyadZSADf2MRuS5bOSTAUR9_mRF6GacVw/s320/eq_78.png" width="320" /></a></div>
<br />
is readily solved to yield the achieved target jerk and snap
according to Eq. (22.9). Solving for the ZG-component of
achieved target jerk provides a check on the computation of
T by the guidance algorithm; agreement between achieved and
input values is typically to seven places.
<br />
<br />
In preparation for correcting estimates at the terminus, the
complete state at terminus is computed by Eq. (22.10).
Equation (22.10) yields a terminal state at the specified
terminal time <span style="color: blue;"><i>TBRF</i></span> precisely, whereas the state <span style="color: blue;"><i>RG</i></span>, <span style="color: blue;"><i>VG</i></span>
applies at the time <span style="color: blue;"><i>T</i></span> which may differ from <span style="color: blue;"><i>TBRF</i></span> by up to
the 2-second granularity.
<br />
<br />
Equation (22.11) corrects the P63 terminal mass estimate
using the rocket equation. Equations (22.12) - (22.14)
correct the terminal acceleration, jerk, and snap using the
corrected P63 terminal mass estimate, the achieved
XG-component of terminal jerk, and the achieved XG- and
ZG-components of terminal snap.
<br />
<br />
Finally, state convergence test quantities are computed by
Eqs. (22.15) - (22.17). Since only three conditions
(<span style="color: blue;"><i>JBRFGAx</i></span>, <span style="color: blue;"><i>SBRFGAx</i></span>, and <span style="color: blue;"><i>SBRFGAz</i></span>) defining the braking-phase
quartic are sought iteratively, only three convergence
criteria are needed. The three criteria chosen are important
for guidance performance and are related non singularly to
three conditions sought. If any one of the state convergence
tests fails, or if the throttle control recovery time
convergence test fails, the braking-phase targets are
corrected and another simulation is run; otherwise the
targeting is concluded by correcting the ignition algorithm
inputs per Eq. (22.18).
<br />
<br />
The P66 vertical channel was developed by <u><i>Craig W.
Schulenberg</i></u>. The analytical design and gain setting of the
P66 horizontal channels was done by <u><i>Nicholas J. Pippenger</i></u>
using concepts suggested by <u><i>Jerrold H. Suddath</i></u>. The concept
of analytically extrapolating to yield the predictive
guidance equation for P63 and P64 was conceived by <u><i>William
S. Widnall</i></u>. The existence of an analytical solution for the
guidance frame orientation to yield zero crossrange target
jerk was recognized by <u><i>Thomas E. Moore</i></u>. The thrust direction
filter configuration for eliminating thrust-pointing errors
due to attitude bias within the digital autopilot deadband
was conceived by <u><i>William S. Widnall</i></u> and <u><i>Donald W. Keene</i></u>."
<br />
<br />
<br />
<br />
<h4>
AUTHORS</h4>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<span style="color: #cc0000;"><i>[<span style="color: #cc0000;"><i><span style="font-size: small;"><u>Allan R. Klumpp</u> - "1963 he joined the MIT Instrumentation Laboratory (later
renamed the Draper Laboratory) to work for the “more ambitious” Apollo
program. Though determined not to take all of the credit (he is quick to
acknowledge that the equations used were derived years earlier by
George W. Cherry), Klumpp was the principal designer of the Apollo Lunar
Module on-board descent software."</span></i></span> </i></span><br />
<span style="color: #cc0000;"><i><br /></i></span>
<br />
<span style="color: #cc0000;"><i><u>George W. Cherry</u> - "Spent the majority of his career as a computer scientist and
programmer for MIT. He authored several books in the area of computer
programming, including "Pascal Programming Structures," "Parallel
Programming in ANSI Standard" and "Software Construction by Object
Oriented Pictures." However, one of George's greatest achievements was
writing the "Apollo Lunar Landing Guidance Scheme" for NASA's Apollo
mission."]</i></span><br />
<br />
<br />
<h4>
REFERENCES
</h4>
<br />
<br />
/1/ Kriegsman, B.A., "Radar-Updated Inertial Navigation of a
Continuously-Powered Space Vehicle", IEEE Aerospace Systems
Conference, Seattle, Washington, July 11-15, 1966.<br />
<br />
/2/ Widnail, W.S., "Lunar Module Digital Autopilot", Journal
of Spacecraft and Rockets, Vol. 8, No. i, January 1971.
<br />
<br />
/3/ Cherry, G.W., "E Guidance -- A General Explicit,
Optimizing Guidance Law for Rocket-Propelled Spacecraft",
MIT Instrumentation Laboratory Report R-456, August 1964.
<br />
<br />
/4/ Klumpp, A.R., "A Manually Retargeted Automatic Descent
and Landing System for LEM", MIT Instrumentation Laboratory
Report R-539, March 1966.
<br />
<br />
/5/ Klumpp, A.R., "A Manually Retargeted Automatic Landing
System for the Lunar Module (LM)", Journal of Spacecraft and
Rockets, February 1968.
<br />
<br />
/6/ Moore, T.E., G.G. McSwain, and J.D. Montgomery,
"Guidance Laws for Controlling Off-Nominal LM Powered
Descent Trajectories Back to the Nominal", Internal Note
MSC-EG-69-9, Project Apollo, NASA, Manned Spacecraft Center,
Houston, Texas, February 28, 1969.
<br />
<br />
/7/ McSwain, G.G. and T.E. Moore, "False High Gate Targeting
for LM Powered Descent", Internal Note MSC-EG-68-07, NASA,
Manned Spacecraft Center, Houston, Texas, May 27, 1968.
<br />
<br />
/8/ Yang, T.L., "A Targeting Seheme for Fuel Optimal Rocket
Trajectories -- With Applications to the LM Descent Braking
Phase", Technical Memorandum TM-71-2014-I, Bellcomm January
22, 1971.
<br />
<br />
/9/ MIT Charles Stark Draper Laboratory Report R-567,
"Guidance System Operations Plan for Manned LM Earth Orbital
and Lunar Missions Using Program Luminary ID", Section 5,
Guidance Equations, Rev. 9, December 1970.
<br />
<br />
/10/ Eyles, D.E., "Apollo LM Guidance and Pilot-Assistance
During the Final Stage of Lunar Descent- Software
Considerations", Fourth IFAC Symposium on Automatic Control
in Space, Dubrovnik, Yugoslavia, September 6-10, 1971.
<br />
<br />
/11/ Klumpp, A.R. and G.R. Kalan, "Elimination of Noise and
Enhancement of Stability and Dynamic Response of the Apollo
LM Rate-of-Descent Program", MIT Charles Stark Draper
Laboratory Report E-2543, October 1970.
<br />
<br />
/12/ Klumpp, A.R., "FINDCDUW -- Guidance Autopilot Interface
Routine", MIT Instrumentation Laboratory LUMINARY Memo No.
27, Rev. i, September 26, 1968.
<br />
<br />
/13/ Bennett, F.V., "Lunar Descent and Ascent Trajectories",
AIAA Eighth Aerospace Sciences Meeting, New York, January
19-21, 1970.
<br />
<br />
/14/ Bennett, F.V., "Mission Planning for Apollo Lunar
Module Descent and Ascent", to be published as a NASA
Technical Note.<br />
<br />
/0/ Klumpp, A.R., "Apollo Lunar-Descent Guidance", MIT
Instrumentation Laboratory Report R-695, DSR Project
55-23890, Manned Spacecraft Center (MSC) of the National
Aeronautics and Space Administration (NASA) Contract
NAS9-4065, June 1971.
<br />
<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2g7AMaZ_KGm1EED5vrSwc1OnC0IKkaDmBvYs4sycP352f6C1VbUtuAP1ruje4jBQsnftrUsanuZtgFvpDHa_WL0moK5DgnP1JR1-Z3WlzzJg3jtcWRW6eKEkKzeODQLXA8v8d_01O3lOl/s1600/Greek-Alphabet-Chart-Letters.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2g7AMaZ_KGm1EED5vrSwc1OnC0IKkaDmBvYs4sycP352f6C1VbUtuAP1ruje4jBQsnftrUsanuZtgFvpDHa_WL0moK5DgnP1JR1-Z3WlzzJg3jtcWRW6eKEkKzeODQLXA8v8d_01O3lOl/s400/Greek-Alphabet-Chart-Letters.JPG" width="393" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Greek alphabet chart.</span></i></span></td></tr>
</tbody></table>
<br />
<h4>
NOMENCLATURE
</h4>
<br />
Symbols are normally defined where first introduced.
Therefore it is necessary to define here only those symbols
used in more than one section of this report. Most symbols
are self-defining by being constructed of standard
identifiers as follows:
<br />
<br />
1.Type of variable. Position and its derivatives velocity,
acceleration, jerk, and snap are denoted R, V, A, J, S.
Thrust is denoted F, thrust acceleration AF, unit vectors
U_N, clock-times by lower case t, and target-referenced
times (times with respect to the target point of a
particular mission phase) by upper case T.
<br />
<br />
2. Mission phase. The braking phase (P63) is denoted BR, the
approach phase (P64) AP.
<br />
<br />
3. Applicable point in phase. Inception is denoted I,
terminus F, and target point T.
<br />
<br />
4. Coordinate frame of reference. Platform coordinates are
denoted P, guidance G, and LM body B.
<br />
<br />
5. Achieved (as opposed to nominal) values are denoted A.
<br />
<br />
Thus by construction, R_BRFGA is the position vector
expressed in guidance coordinates achieved at the braking
phase terminus. Without a phase identifier, R_TG to S_TG
represent the braking or approach phase targets R_BRTG to
S_BRTG or R_APTG to S_APTG, whichever phase is current.
Vector elements are denoted by subscript, e.g., Vz. Vector
magnitudes are implied whenever a symbol reserved for a
vector lacks the underscore. Row vectors of 3 x 3 matrices
are denoted C_x, C_y, C_z, and matrix elements are
identified by row and column, e.g., Cyz is the Z component
of the row vector C_y. (The vector sign underscore can be
below the first letter, above it, or after it.)
<br />
<br />
<br />
<div style="text-align: center;">
* * *
</div>
<br />
<br />
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-85518100857247485312016-12-05T04:27:00.001+00:002016-12-05T05:04:59.040+00:00(Mars) Vehicle "2500" - Part 2 - The PlansBasically if the target planet or object has less gravity than Mars and/or any atmosphere or not at all like Earth's Moon this vehicle should be fine. It differs from the Apollo Lunar Module in those parts which require aerodynamics but is otherwise similar. It can be used with some amount of AB (aero braking) but it can also handle braking with rockets alone. If much gas is available for braking then less fuel is required and that mass can be used for transport purposes if required. So basically our design is a general purpose lander, but fits best to Mars, Moons etc.<br />
<br />
Here is the more detailed general plan of the vehicle "2500".<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7UT-INDDHcHy8xGqpSMKZh5A0tVDNw-EBeaACdvjpQ_ATuUdnxwwx37foufJrPWz_MdAgFGbmgFwtsMCE3oPUwNq1VxmH83jZiwCFr93uxoodv5rHDaW9b3VbwDh4gp2MsnGm8MwO9mZE/s1600/Mars_Vehicle_005.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7UT-INDDHcHy8xGqpSMKZh5A0tVDNw-EBeaACdvjpQ_ATuUdnxwwx37foufJrPWz_MdAgFGbmgFwtsMCE3oPUwNq1VxmH83jZiwCFr93uxoodv5rHDaW9b3VbwDh4gp2MsnGm8MwO9mZE/s400/Mars_Vehicle_005.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. General purpose lander for Mars, Moons, etc.</span></i></span></td></tr>
</tbody></table>
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<a name='more'></a>It is the standard 2 stage Apollo style vehicle. The lower part is the descent part with much as possible gas resistance and the upper part is the ascent stage with somewhat aerodynamic body to help it through the gases. The total maximum mass of the configuration is 150 000 lbs and with that amount of fuel it can do the Mars landing and return to LMO (Low Mars Orbit) without any help of aerodynamic braking. It can also handle the Earth's Moon and all other objects with less gravity than Mars.<br />
<br />
The weight of the ascent stage is 20 000 lbs with all propellant included. All stages use typical Apollo style bi propellants and rockets have the Apollo nominal specific impulses (Isp) 311 seconds.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmghZNDmzn0bFB4z8GEvro6y4owcR_8rl6ulUS56NAv6rhIaHWTxvk_8RqDTKNXGbbPUCv2X9JE8PxxBY8E7PVJzP25sBuKhXOJ-gM3MyngWwKfwSe9qaY4I3A3317m5xgPpieMAvWgpSp/s1600/Mars_Vehicle_006.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmghZNDmzn0bFB4z8GEvro6y4owcR_8rl6ulUS56NAv6rhIaHWTxvk_8RqDTKNXGbbPUCv2X9JE8PxxBY8E7PVJzP25sBuKhXOJ-gM3MyngWwKfwSe9qaY4I3A3317m5xgPpieMAvWgpSp/s400/Mars_Vehicle_006.PNG" width="260" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure
2. The descent stage with balanced bi propellant ball tanks. Notice
that there is additional room to carry cargo etc. on the center heat
shield.</span></i></span></td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
The descent stage landing gear is actually a combined fuel tank, foot pad, one shot strut, and heat shield. If the landing object has gas atmosphere then the foot pad heat shields and the center heat shields are covered with <a href="https://en.wikipedia.org/wiki/Atmospheric_entry#Ablative" target="_blank">ablative</a> material .. and everything else also such that the surfaces can sustain the landing. At touch down the foot pad heat shield works as a foot pad and the one time struts take the landing impact energies .. so that the touch down is as smooth as possible. The final (if not the whole) phase of the landing is powered as with Apollo flights and the descent rocket does most of the braking and hovering work. It is flown like a helicopter to the desired point (automatically or manually).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbbsiUjPd_W_M-Xe48VCLH7GxgyFJ5mNS0bvVBfBDfrgdOe3YbCE_LrX_dEBLQ9r78uq5PY5yamUO0JUqGct7PVUUfRNLje_dXJIejNXgEQhXjb75AIab3fw0tJIKIlwEfCOqnAxvQZcHd/s1600/Mars_Vehicle_004.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="337" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbbsiUjPd_W_M-Xe48VCLH7GxgyFJ5mNS0bvVBfBDfrgdOe3YbCE_LrX_dEBLQ9r78uq5PY5yamUO0JUqGct7PVUUfRNLje_dXJIejNXgEQhXjb75AIab3fw0tJIKIlwEfCOqnAxvQZcHd/s400/Mars_Vehicle_004.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. The ascent stage is rather nominal type rocekt.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Some effort is seen to give the pilots much as possible visibility to the landing spot as early as possible. The overall planning of the landing trajectory is done so that the required flight attitude is reached at right time so that the pilots can see the landing area (as in Apollo LM landings).<br />
<br />
The egress hatch is under the pilots flight positions and the lower part of the stage is not pressurized. The ladder slides down and the door opens to make the exit and entry possible for the astronauts. The fuels are located in the C.G. to keep the vehicle C.G. centered regardless of the amounts of propellants.<br />
<br />
We will later return to this vehicle when doing some landing simulations with it. <br />
<br />
<div style="text-align: center;">
* * *</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-5594282590244782972016-11-25T01:34:00.000+00:002016-12-05T05:04:59.036+00:00Mars Vehicle "2500" - Part 1 - BasicsThis Mars Vehicle (MV), model "2500" is part of the <a href="https://dodlithr.blogspot.fi/2015/10/leamor-mission-light-extended-apollo.html" target="_blank">LEAMOR</a> (Light Extended Apollo Mars Orbit Rendezvous) total mission plan. See the article for general ideas about that Mars mission plan.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid43Iqxo71XCK-vfjdf4TbKPRcUb7V4PlbuFHX2N0ovvvlMq6tdHn2ogMvHwFltR2Ad2L-ZjpH-vnpoyiir_oK9gVVDZY6D6jnzrJkvhmaR2iLQ6JylD5W-RLMumK69Dq8SictxJjJY5tw/s1600/Mars_Vehicle_002.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="302" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEid43Iqxo71XCK-vfjdf4TbKPRcUb7V4PlbuFHX2N0ovvvlMq6tdHn2ogMvHwFltR2Ad2L-ZjpH-vnpoyiir_oK9gVVDZY6D6jnzrJkvhmaR2iLQ6JylD5W-RLMumK69Dq8SictxJjJY5tw/s400/Mars_Vehicle_002.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. Mars Vehicle (MV) "2500" with ablative lower part and heat shield above ablative fuel balls.</span></i></span></td></tr>
</tbody></table>
<br />
<a name='more'></a><br />
Figure 1 shows how the Mars Vehicle (MV) model "2500" looks like. It is typically a 150,000 lbs bi propellant standard LM (Apollo Lunar Module) type configuration before Descent Orbit Insertion (DOI). That is the typical maximum mass but the mass could be less if all aerodynamic braking (AB) and best optimal descent trajectories were used. As the Apollo Lunar Module it has also 2 stages: descent and ascent.<br />
<br />
As the Apollo LM the LEAMOR MV will also be transported to the Low Mars Orbit and wait there until the manned Mars landing will take place. So it is not meant to carry any large cargo outside the astronauts since those could be sent more direct and less secure routes directly to the Mars surface (using for example so called Mars direct concept).<br />
<br />
Here are the basic MV burn calculations repeated again for the descent and ascent with masses. Safety factor 1.3 for propellants. (<a href="http://dodlithr.blogspot.fi/2015/10/delta-v-calculator-rocket-equation.html" target="_blank">The Rocket Equation used</a>).<br />
<br />
<ul>
<li>MV full 150 t (about max SLS, later maybe more)</li>
<li>MV dry 27 t</li>
<li>AS full 20 t</li>
<li>AS dry 3.5 t (3500 lbs)</li>
<li>DS dry 7 t (7000 lbs)</li>
<li>Isp both 311 s</li>
<li>Results delta-V: MV = 5.2 km/s and AS = 5.3 km/s (~ 1.3 x 4.1 km/s)</li>
</ul>
<br />
Notice that the descent stage is as wide as possible to add much as possible drag when entering Mars thin atmosphere .. on the other hand the ascent stage is slender to help it to reach the required orbital speed through the atmosphere. Lower fuel balls have double skin to help them handle the entry heat and covered with <a href="https://en.wikipedia.org/wiki/Atmospheric_entry#Ablative" target="_blank">ablative</a> shielding material. Since they a hard enough the landing gears are directly attached to them. Also the descent engine and the small heat shield above it is covered with ablative layer.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
This vehicle can ALSO land to the Earth's Moon (and many other places) without any problem (due to much lower gravity than Mars) .. and the ablative layer is not required with the Earth's Moon since it does not have any atmosphere at all.<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWaQwCe_UmeZeOkzd44s8t31XPJ6rCEV8Vps4UgD9xWKrFZANwUO6G3xgPiKKN_wwA49RMwo5dkH9fF5ynD3Lw3rAhgwiotrjxKjT8QFhduRMWNVIOTVpCZG9SORh8hFOIp7INM0Hzu4j6/s1600/Mars_Vehicle_003.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="302" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjWaQwCe_UmeZeOkzd44s8t31XPJ6rCEV8Vps4UgD9xWKrFZANwUO6G3xgPiKKN_wwA49RMwo5dkH9fF5ynD3Lw3rAhgwiotrjxKjT8QFhduRMWNVIOTVpCZG9SORh8hFOIp7INM0Hzu4j6/s400/Mars_Vehicle_003.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 2. Some additional details.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 2 shows some additional details like, how the nose cone opens to allow docking and how the fuel lines are installed.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYD4iJ3iuIYjwLKy3tZo95wB-gTvF6RfQkSA1BLpHlldp8WUHbZpYQpZRM7VPCk9APYKNcaNanB9c09b3_BGRzO3YLCUBaxq4OSyN0O6lMyGoDRg3qy8F95UeXvL5Xesr0EMXEr6B0XV6P/s1600/Blunt_body_reentry_shapes.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="337" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiYD4iJ3iuIYjwLKy3tZo95wB-gTvF6RfQkSA1BLpHlldp8WUHbZpYQpZRM7VPCk9APYKNcaNanB9c09b3_BGRzO3YLCUBaxq4OSyN0O6lMyGoDRg3qy8F95UeXvL5Xesr0EMXEr6B0XV6P/s400/Blunt_body_reentry_shapes.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. Some usual atmospheric entry forms.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 3 shows some usual re-entry body forms. Since most (or all) of the braking is done by the descent rocket thrust the drag body shape is not important it is there just to give some additional drag and prevent the burning of the surface by hot plasma.<br />
<br />
<br />
<span style="color: #0c343d;"><b>See also:</b></span><br />
<br />
/1/ <a href="https://dodlithr.blogspot.fi/2015/10/leamor-manned-mars-mission-why-modular.html#more" target="_blank">LEAMOR MV</a><br />
<br />
<div style="text-align: center;">
* * *</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-10885832721552101692016-11-22T00:12:00.001+00:002016-12-07T03:41:46.002+00:00LM Descent to the Moon - Part 5 - Powered Landing Maneuver (1964)<div class="separator" style="clear: both; text-align: center;">
</div>
<div class="separator" style="clear: both; text-align: center;">
</div>
(LEM Powered Landing Maneuver, 1964)<br />
<br />
<span style="color: #274e13;"><i>[This is a partial reprint of a 1964 technical paper from MIT/NASA, which explains the mathematics behind the 1960's lunar landings. See /1/ for details. LM was called LEM (Lunar Excursion Module) those days and the first landing was to be done summer 1969, 5 years after this paper was written. The strength of this algorithm is that it is real time adaptive to the variations of the parameters from different sources (and also errors). This algorithm was called "E Guidance" due to the E matrix used in it. T</i></span><span style="color: #274e13;"><i>he basic LM descent guidance logic was defined by an acceleration command which
was a quadratic function of time and was, therefore, later termed "Quadratic Guidance".
]</i></span><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBagpUOz3Qi1RbPG_r43YwUG_mkMZn0x_YVBSZtfUyFD88m7HWJu0wIEWijfl8Nbt1PzSHnfyJScdKnkpoXI8Itp2Az5M9gIOsNqcBYjZGxV5OiRl8Qsin0NpP7HKkSqtFK3FObCosTROR/s1600/Look_and_Thrust_Angle.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBagpUOz3Qi1RbPG_r43YwUG_mkMZn0x_YVBSZtfUyFD88m7HWJu0wIEWijfl8Nbt1PzSHnfyJScdKnkpoXI8Itp2Az5M9gIOsNqcBYjZGxV5OiRl8Qsin0NpP7HKkSqtFK3FObCosTROR/s400/Look_and_Thrust_Angle.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #990000;"><span style="color: #e06666;"><i><span style="font-size: small;">Figure 0. Look angle "lambda" is relative to the thrust axis</span></i></span></span></td></tr>
</tbody></table>
<br />
<a name='more'></a><br />
<h2>
POWERED LANDING MANEUVER /1/
</h2>
<br />
<br />
<h4>
1 General Description
</h4>
<br />
"The powered part of the landing maneuver starts at the LEM
engine ignition point of the descent orbit and terminates at
lunar surface touchdown. The LEM powered landing maneuver
has been divided into the three major phases illustrated in
Fig. 1.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipuOdTsKb2fONkoWah443Bx2N3EzVcHPAKINGpiNVFetG9FZ1dpQDZmh4_FseGCgogc9o0Rm58PcBpUGdEK8VLe7rJjpdmoWJrUwdSQ2GFWkKcp5i3KSfGKM0gN1E2rjKia9PWR6fEduw4/s1600/Fig_4_1.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipuOdTsKb2fONkoWah443Bx2N3EzVcHPAKINGpiNVFetG9FZ1dpQDZmh4_FseGCgogc9o0Rm58PcBpUGdEK8VLe7rJjpdmoWJrUwdSQ2GFWkKcp5i3KSfGKM0gN1E2rjKia9PWR6fEduw4/s400/Fig_4_1.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1. Lunar landing maneuver phases</span></i></span></td></tr>
</tbody></table>
<br />
<ol>
<li><u>The first phase</u> is inertially guided and is the
longest with respect to time and ground range. The primary
GN (Guidance and Navigation) system objective of the first phase, is to achieve a
position and velocity condition for the start of the second
phase which will allow a near constant vehicle attitude and
landing site visibility as the LEM approaches the surface.
The scale of Fig. 1 is exaggerated in that the landing
site is below the lunar horizon relative to the engine
ignition point and does not come within view until the LEM
is about 125 n.m. away. For the optimum <span style="color: blue;"><i>dV</i></span> type landing
trajectory, the landing site is not visible with the current
LEM window configuration until hover conditions have been
achieved. For this reason the landing trajectory is shaped
such that a vehicle attitude that permits landing site
surveillance is achieved during some phase of the maneuver.</li>
<li>The desired vehicle attitude during <u>the second phase</u> is such
that the astronauts can visibly check the landing area
through the LEM windows. The second phase is guided at
approximately half-maximum throttle setting in order to
lengthen the maneuver time to about two minutes for visual
and landing radar updating of the inertial guidance units.
The terminal objective of the second phase is to achieve
hover or zero velocity conditions over the desired landing
site at some pre-designated altitude.</li>
<li><u>The third phase</u> is the
let-down and surface landing from the hover condition.
</li>
</ol>
<br />
<br />
<br />
<h4>
2 Lunar Landing Steering Equations
</h4>
<br />
<span style="color: #0c343d;"><b>2.1 General Comments
</b></span><br />
<br />
The lunar landing steering equations are a direct, exact
solution to the equations of motion. They express the
solution thrust vector as an explicit function of the
current position and velocity vectors and the desired
position and velocity vectors. Figure 2 is a simple block
representation of the equations.<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUHzPJcVDaEpzmXULGO3HFl9tXdabLwKvRXKY1zUmPkKsqxeHKm6eW1PUeOD4DX3kckuWm6lQu2PWtpq-eES0Om2frij-EAxSjjBuNYDBzZ7bYWDWWAq8fMwuCHx2e6JSj_dl0zrtg1fiE/s1600/Fig_4_2.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhUHzPJcVDaEpzmXULGO3HFl9tXdabLwKvRXKY1zUmPkKsqxeHKm6eW1PUeOD4DX3kckuWm6lQu2PWtpq-eES0Om2frij-EAxSjjBuNYDBzZ7bYWDWWAq8fMwuCHx2e6JSj_dl0zrtg1fiE/s400/Fig_4_2.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 2. Block diagram of Lunar landing equations.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
In mathematical parlance,
the lunar landing equations are a solution to a two-point
boundary-value problem. The first point is the <u>current state</u>
(point in state space); the second point is the <u>desired
state</u>. Because the equations express the components of the
solution thrust acceleration vector as explicit algebraic
functions of literal symbols for the current and desired
states, any meaningful and physically reasonable numerical
values may be substituted for the literal symbols. This
flexibility of the landing equations is quite significant
because at least two, and probably more than two, different
boundary-value problems will be posed to the guidance system
during the landing maneuver.
<br />
<br />
If the first two phases of the landing maneuver (from engine
ignition to the hover point) were accomplished in one
powered maneuver, the attitude orientation of the vehicle
would be such that the astronaut would never see the landing
site. The look angle, i.e. the angle between the
line-of-sight to the landing site and the vehicle's negative
thrust axis, must be greater than 25°. Typical vehicle
attitudes and phase 2 initial conditions are illustrated in
Fig. 3.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivR9TKyxjKX5MAkaz1Nf4Sv_GedFBWZT86kAVU92E_Z7yiU94zvqcpG2tA2pixKbRv8gsPBTANQBKy13AYZdPOcc4EVDin7as58SbhNDiSSDlQZBwzEZsrCS12jZNgVbO_3FOD_cJCN-tl/s1600/Fig_4_3.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEivR9TKyxjKX5MAkaz1Nf4Sv_GedFBWZT86kAVU92E_Z7yiU94zvqcpG2tA2pixKbRv8gsPBTANQBKy13AYZdPOcc4EVDin7as58SbhNDiSSDlQZBwzEZsrCS12jZNgVbO_3FOD_cJCN-tl/s400/Fig_4_3.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 3. Lunar landing maneuver - phase 2.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The initial conditions for phase 2, which are also
the terminal conditions for phase 1, are chosen so that the
phase 2 sink rate (downward vertical rate) is comfortable
and the phase 2 look angle is suitable.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6fXVKc7sW5Da_HKAxsTdxcVPHkTCSHbc8SmkZm1RU5wa7SoK8tnCOgrzxsGLALl3yIlG0kqz8LYvqur2AUM19T5YKOvlaYkN9ggFbowmhf87-FXDaije-sOk3edWiDRfSt0GgdGb9NSRi/s1600/Fig_4_4.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6fXVKc7sW5Da_HKAxsTdxcVPHkTCSHbc8SmkZm1RU5wa7SoK8tnCOgrzxsGLALl3yIlG0kqz8LYvqur2AUM19T5YKOvlaYkN9ggFbowmhf87-FXDaije-sOk3edWiDRfSt0GgdGb9NSRi/s400/Fig_4_4.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 4. Thrust axis vs. time.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figures 4 and 5
show that at the terminus of phase 1 (the start of phase 2)
the vehicle is rotated through approximately 30° and the
thrust magnitude is reduced.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJz6HEUoO7UND3qzgiUdLzbSq72L1aACurb4S6F-ZhMVKt3DMB8Os69fgpJFSiH4tse4_aksswQRaIC7-G3k5HcXtUGW-ZuncUkftpsmkQaK1RGyCqBNlB6_bBcz8b_RWjNDUcI1BlBRyc/s1600/Fig_4_5.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="267" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJz6HEUoO7UND3qzgiUdLzbSq72L1aACurb4S6F-ZhMVKt3DMB8Os69fgpJFSiH4tse4_aksswQRaIC7-G3k5HcXtUGW-ZuncUkftpsmkQaK1RGyCqBNlB6_bBcz8b_RWjNDUcI1BlBRyc/s400/Fig_4_5.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 5. Thrust magnitude vs. time.</span></i></span></td></tr>
</tbody></table>
<br />
The thrust vector rotation tips the vehicle to an
orientation which allows the astronaut to view the proposed
landing site.
<br />
<br />
Several constraints are imposed on phase 2 of the landing
maneuver - First of all, both final position and velocity
vectors are specified for the terminus of phase 2. It should
be emphasized that all components of the terminal position
and velocity vectors must be controlled. Next, the
spacecraft orientation must be such that the proposed
landing site is in the viewing sector of the spacecraft
window. The sink rate of the spacecraft must be moderate
enough to allow for ascent engine ignitions and
descent-stage separation without a lunar contact in case of
abort; i.e., the altitude and altitude rate profile must
permit aborting the landing maneuver with the ascent engine.
Finally, it would be desirable to standardize the duration
of phase 2 and the evolution of the state vector during the
visibility phase. This would make the astronaut's monitoring
problem somewhat easier and decrease the variation of the
conditions which he should regard as satisfactory.
<br />
<br />
Phase 2 is seen to be heavily constrained. The steering
equations can be regarded as a "black box". The "input" to
the box are the present position and velocity vectors and
the desired position and velocity vectors. The "output" from
the black box are the required thrust vector orientation and
the required thrust acceleration magnitude. The output from
the box cannot be constrained, except indirectly, if the
desired final position and velocity vectors are to be
obtained. Yet it is required that the thrust angle be such
that the look angle be suitable. Furthermore, the equations
explicitly control only the final position and velocity
vectors - the vehicle is not constrained by the equations to
a particular trajectory. To obtain all the characteristics
required of phase 2, the following procedure is used. The
spacecraft is mathematically "flown backwards" from the
hover conditions for the number of seconds-desired in phase
2. As the vehicle progresses backwards from the hover point
the thrust angle is set such that the View of the landing
site is acceptable. A suitably low altitude rate is also
maintained. At the end of this hypothetical backwards
flight, the vehicle's position and velocity are observed.
This observed position and velocity are specified to be the
terminal state for phase 1. Thus the terminal conditions for
phase 1 are just those appropriate initial conditions for
phase 2 which would produce the desired phase 2
characteristics. It is to be emphasized that during the
landing maneuver the thrust vector is not directly
constrained to obtain an adequate look angle. The thrust
vector is computed as a solution to the two-point
boundary-value problem. The phase 2 two-point boundary-value
problem is arranged, by the choice of the initial phase 2
boundary point, so that it requires as a solution a suitable
thrust angle regime.
<br />
<br />
To further illustrate the procedure of choosing the terminal
conditions for phase 1, a very simple method of finding
appropriate initial conditions for phase 2 follows. This
method involves a simple solution to a set of simultaneous
linear equations. Consider Fig. 6 in which a coordinate
system and equations of motion satisfactory for phase 2 are
given.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJQBJ5ZChrdLNCFSwSpm5GJvxh6kbk75lfZB3JxtJYXsKfwKbRebvEex2oGTOF2HY8Vk5HsTBmHrm4P4I6dj3HCsu0jV4PHfZXGnV60IhCcf0B4KVMhMtL7zFzI3GPtm5MgC3So7kyfAMb/s1600/Fig_4_6.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjJQBJ5ZChrdLNCFSwSpm5GJvxh6kbk75lfZB3JxtJYXsKfwKbRebvEex2oGTOF2HY8Vk5HsTBmHrm4P4I6dj3HCsu0jV4PHfZXGnV60IhCcf0B4KVMhMtL7zFzI3GPtm5MgC3So7kyfAMb/s400/Fig_4_6.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 6. "Flat Moon"</span></i></span></td></tr>
</tbody></table>
<br />
These equations represent the moon as <i>"flat"</i>, a
representation which is quite satisfactory for phase 2 since
the angular travel of the spacecraft is normally less than
1° during the visibility phase. If the coordinate system
in Fig. 6 is chosen so that the y-axis passes through the
intended hover point, the differential equations of motion
are
<br />
<br />
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</div>
<div class="separator" style="clear: both; text-align: center;">
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<br />
Note that <span style="color: blue;"><i>y</i></span> and <span style="color: blue;"><i>y_dot</i></span> are equivalent to altitude and
altitude rate, and <span style="color: blue;"><i>x</i></span> is equivalent to range-to-go to hover.<br />
<br />
Equation (1) can be integrated between the initiation of
phase 2 and the finish of phase 2.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMFvtfOEaeifduYE6PO2jVhPzSrkfIjPeToDeUEPzK1BuPdqE9AqWr0gt20GpDhMDTqWxnkep0uvdbdMxtwm_GCkXhWieTqWJGyeKr_fIu_wIGf4Fsi_yi9SmjFHFBeSCpKSgHOUS_OLf_/s1600/eq_3_4.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="100" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMFvtfOEaeifduYE6PO2jVhPzSrkfIjPeToDeUEPzK1BuPdqE9AqWr0gt20GpDhMDTqWxnkep0uvdbdMxtwm_GCkXhWieTqWJGyeKr_fIu_wIGf4Fsi_yi9SmjFHFBeSCpKSgHOUS_OLf_/s400/eq_3_4.gif" width="400" /></a></div>
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<br />
where <span style="color: blue;"><i>Tpf </i></span>= time of powered flight for this phase.
Similarly, Eq. (2) is integrated to give:
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8JNnarOxyc5WLcYODtSmHHJppgbtTnpSLcr9ZxbJsp_3TNSRCWWGL70yrZN_XKHQcp75F68qIdLm5QZumfum3cMEZ6OmXbDqhVbTBYRopNLYWY_EXzPiNXzxYi4cyL290FP2_fUx8EyLq/s1600/eq_5_6.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="80" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj8JNnarOxyc5WLcYODtSmHHJppgbtTnpSLcr9ZxbJsp_3TNSRCWWGL70yrZN_XKHQcp75F68qIdLm5QZumfum3cMEZ6OmXbDqhVbTBYRopNLYWY_EXzPiNXzxYi4cyL290FP2_fUx8EyLq/s400/eq_5_6.gif" width="400" /></a></div>
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</div>
<br />
In Eqs (3) - (6), <span style="color: blue;"><i>aT</i></span> can be a constant or a varying thrust
acceleration due to a constant thrust engine. Equations
(3) - (6) express a relationship among <span style="color: blue;"><i>initial (i)</i></span> and <span style="color: blue;"><i>final
(f)</i></span> vector conditions of phase 2; the duration of phase 2, <span style="color: blue;"><i>Tpf</i></span>; the assumed constant thrust angle during phase 2, <span style="color: blue;"><i>alpha_0</i></span>; and the thrust acceleration during phase 2, <span style="color: blue;"><i>aT</i></span>. Since the hover
position and velocity vectors are specified, all the
f-subscripted variables are fixed. The thrust angle, <span style="color: blue;"><i>alpha_0</i></span>, is
chosen to yield a suitable look angle. The phase 2 duration,
<span style="color: blue;"><i>Tpf</i></span> is chosen to allow the astronaut sufficient time to view
the proposed landing site. The sink rate at the initiation
of phase 2, <span style="color: blue;"><i>yi_dot</i></span> must be limited to a moderate value, for
the reasons mentioned previously. Since each of the
quantities <span style="color: blue;"><i>yi_dot</i></span>, <span style="color: blue;"><i>yf_dot</i></span>, <span style="color: blue;"><i>Tpf</i></span>, and <span style="color: blue;"><i>alpha_0</i></span> , must be chosen to
satisfy some operational constraint. the only free variable
left in Eq (5) is <span style="color: blue;"><i>aT</i></span>. Consequently. the value of <span style="color: blue;"><i>aT</i></span> is
fixed by Eq. (5), and this equation is separately
satisfied. The remaining equations, Eqs (3), (4), and
(6), have only three unknowns, namely, <span style="color: blue;"><i>xi</i></span>, <span style="color: blue;"><i>yi</i></span>, and <span style="color: blue;"><i>xi_dot</i></span>.
The solution for the unknowns is given by the following
matrix-vector equation<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaZ1gRnvHCVdCXdAGz-2nczux9s35Euxv4QHmi3PfqZgsPdkdhQoOcmbUn_1ilpoDoCSPPGl7uNp_u5nVBs4jgwF8jb-zv38xiQvOBJtgHZe9OoFgGbgWlIJtogcnNtnJjT8hSKHgJKQIc/s1600/eq_7.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="52" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgaZ1gRnvHCVdCXdAGz-2nczux9s35Euxv4QHmi3PfqZgsPdkdhQoOcmbUn_1ilpoDoCSPPGl7uNp_u5nVBs4jgwF8jb-zv38xiQvOBJtgHZe9OoFgGbgWlIJtogcnNtnJjT8hSKHgJKQIc/s400/eq_7.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><i><span style="font-size: small;">(7)</span></i></b></td></tr>
</tbody></table>
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<br />
The quantities on the right-hand side of Eq (7) are chosen
to yield the desired phase 2 trajectory characteristics. The
quantities on the left-hand side of Eq (7) are the missing
phase 2 initial boundary conditions.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgscHxgWgmeY9jExtY92KvcSPXUp0jKrmDD8uuIzq9W5FxruYsquSuZabOd9mScoqXM8i0sQRtIrsbvnusqI_0lKRxpZ_tP7yGfi2aCYsWLn1Kg6K3jf0m2g-LsA1qPpOdt-reIfAQGXGdI/s1600/Fig_4_7.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgscHxgWgmeY9jExtY92KvcSPXUp0jKrmDD8uuIzq9W5FxruYsquSuZabOd9mScoqXM8i0sQRtIrsbvnusqI_0lKRxpZ_tP7yGfi2aCYsWLn1Kg6K3jf0m2g-LsA1qPpOdt-reIfAQGXGdI/s400/Fig_4_7.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 7. Hover point position viewing geometry.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The thrust angle required for a suitable look angle can be
determined by picturing the spacecraft at the hover point.
Figure (7) shows the hover point geometry and the equation
for the thrust angle, <span style="color: blue;"><i>alpha_0</i></span>, in terms of the altitude at hover, <span style="color: blue;"><i>yf</i></span>,
the linear distance between the hover sub-point and the
landing point, <span style="color: blue;"><i>l</i></span>, and the required look angle, <span style="color: blue;"><i>lambda</i></span>. The shorter the
distance <span style="color: blue;"><i>l</i></span> between the hover sub-point and the landing
point, the steeper <span style="color: blue;"><i>alpha_0</i></span> must be for an adequate look angle.
But, the steeper the thrust angle during phase 2, the
greater the <span style="color: blue;"><i>dV</i></span> requirement for the descent-to-hover
maneuver. On the other hand, a greater distance <span style="color: blue;"><i>l</i></span> requires a
longer let-down maneuver after the hover point is reached. A
long let-down maneuver from hover uses a large <span style="color: blue;"><i>dV</i></span> as
described in chapter 6. Thus there is some optimum distance,
<span style="color: blue;"><i>l</i></span>, which is neither very short nor very long. For the
examples illustrated in this section, <span style="color: blue;"><i>l</i></span> was arbitrarily
chosen to be 1000 feet. Many operational considerations,
besides <span style="color: blue;"><i>dV</i></span> optimization, must enter into the final
determination of <span style="color: blue;"><i>l</i></span>. It might be noted that it is
advantageous with respect to <span style="color: blue;"><i>dV</i></span> requirements to make the
hover altitude <span style="color: blue;"><i>yf</i></span> as low as possible. The smaller <span style="color: blue;"><i>yf</i></span>, the
smaller<span style="color: blue;"><i> alpha_0</i></span> can be for a given <span style="color: blue;"><i>l </i></span>and required look angle.
<br />
<br />
The determination of the phase 2 terminal conditions, either
by the method described above or any other method which
produces the appropriate initial boundary conditions for
phase 1, is done before the landing maneuver is started. in
fact, these conditions should be determined and stored prior
to Saturn (Apollo Saturn V rocket) launch. The objective of discussing these
intermediate boundary conditions was to show how the desired
characteristics of the final part of the descent-to-hover
maneuver can be obtained by a two-phase descent with
steering equations which solve a two-point boundary-value
problem.
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>2.2 Derivation of Landing Maneuver Guidance Equations</b></span>
<br />
<br />
The differential equations of a rocket-propelled vehicle
subject to gravitational acceleration are:
<br />
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<br />
The gravity vector (row array) is
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqK8l4e21I_5aLhdf6H6r8F5KzfParDH1RdyniwiDgiTqhIDZ6nhlm72R001_XVUuNvtEx8U2wbTWD0CvkiT-AaeXRiz1D-0DOTpKZHF_8uygr9_SicgmedcLUflUyFs4mIDc_KpOoXo7o/s1600/eq_11.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="31" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqK8l4e21I_5aLhdf6H6r8F5KzfParDH1RdyniwiDgiTqhIDZ6nhlm72R001_XVUuNvtEx8U2wbTWD0CvkiT-AaeXRiz1D-0DOTpKZHF_8uygr9_SicgmedcLUflUyFs4mIDc_KpOoXo7o/s320/eq_11.gif" width="320" /></a></div>
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<br />
If the gravitational field is spherical, the gravity vector
is
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUJBDTsSLyI8myZatEZCM8mfSLH7R6oI_0Cotb4nNX6Izq5DstG1CP_NRAlIVEgkSX21nZ-P130GAHqGVsUzD_R6oGXqjgCFXIs45-1oEy7XYzXNu6UPQirvxG_YgNKDotXQ7dbUQ1C44o/s1600/eq_12.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="33" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUJBDTsSLyI8myZatEZCM8mfSLH7R6oI_0Cotb4nNX6Izq5DstG1CP_NRAlIVEgkSX21nZ-P130GAHqGVsUzD_R6oGXqjgCFXIs45-1oEy7XYzXNu6UPQirvxG_YgNKDotXQ7dbUQ1C44o/s320/eq_12.gif" width="320" /></a></div>
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<br />
but the steering equations developed in this section can be
used with any gravitational field model. The problem that
the steering equations must solve is the following: Given
the current position and velocity of the spacecraft:
<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgum6_lCEADUUb4PwVpu3OLxxAcArhyphenhyphen5TuHtDIalJW8n-RSHB8_AbdTHlcbZ5q1ZaLp4MKnY85VCL47GGk1_r9Re-BY0j7nl58tGB1GlQ_CB6r4XBptBKp438pF1i07Fpyp4ePZbsbzqkw1/s1600/eq_13_14.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="63" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgum6_lCEADUUb4PwVpu3OLxxAcArhyphenhyphen5TuHtDIalJW8n-RSHB8_AbdTHlcbZ5q1ZaLp4MKnY85VCL47GGk1_r9Re-BY0j7nl58tGB1GlQ_CB6r4XBptBKp438pF1i07Fpyp4ePZbsbzqkw1/s400/eq_13_14.png" width="400" /></a></div>
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<br />
and the desired values of the components of the terminal
position and velocity vectors
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5uv9HL74pa22D4Rzk-LrW1VSUpuNJ9ttwb1otZzruiSELZUo960tlzrVuVifUxC_m3PCCvba8zXhl1InZrvk2LmxVGponSFEDk79xj0qNr6dR0cgm3jnDWQKBzkVOdGI1duV6b5uv9Jiv/s1600/eq_15_16.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="73" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5uv9HL74pa22D4Rzk-LrW1VSUpuNJ9ttwb1otZzruiSELZUo960tlzrVuVifUxC_m3PCCvba8zXhl1InZrvk2LmxVGponSFEDk79xj0qNr6dR0cgm3jnDWQKBzkVOdGI1duV6b5uv9Jiv/s400/eq_15_16.png" width="400" /></a></div>
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<br />
find a thrust acceleration regime
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHNr3sMyk5UZvIkItWt0eJQh78NXj3TbXBUUC-Dl2j3HOxuunYkKcTNORIFk4eEWztRMJfKA-ecDzqETRCeRVanL3DDuhGpb7I7l_lEIBiByIOb7nCh_1HvKHmwC7-F3UeG0My1NEOR7T7/s1600/eq_17.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="25" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHNr3sMyk5UZvIkItWt0eJQh78NXj3TbXBUUC-Dl2j3HOxuunYkKcTNORIFk4eEWztRMJfKA-ecDzqETRCeRVanL3DDuhGpb7I7l_lEIBiByIOb7nCh_1HvKHmwC7-F3UeG0My1NEOR7T7/s400/eq_17.png" width="400" /></a></div>
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<br />
which satisfies the given boundary conditions and the
appropriate differential equations of motion. Note that <span style="color: blue;"><i>t = t0</i></span>
at the current time and <span style="color: blue;"><i>t = T</i></span> at the terminal time.
<br />
<br />
The solution of a single axis boundary-value problem, e.g.
the x-axis, is first illustrated. The solution is then
expanded for the required 3-dimensional problem.
<br />
<br />
Without regard for the two component parts of <span style="color: blue;"><i>x_dot_dot(t)</i></span>,
the gravitational acceleration and the thrust acceleration,
the following requirements concerning <span style="color: blue;"><i>x_dot_dot(t)</i></span> can be
noted. The first and second integrals of <span style="color: blue;"><i>x_dot_dot(t)</i></span> must
satisfy certain equations of constraint in order for the
x-coordinate boundary conditions to be satisfied.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzYdvxbyxZZH4JDlS8tF5JWXt4FYxpZuo0fwETMftgU3Vl8xYtIiXsaXDsd-k9zGd7HI4hwfxjwM5uOLjCJF_zQUVzFgToJIFjYiGic8HrWVztbYSBuWQqlXXkWNCm86SjShwZTFeb0a2d/s1600/eq_18-22_.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="258" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhzYdvxbyxZZH4JDlS8tF5JWXt4FYxpZuo0fwETMftgU3Vl8xYtIiXsaXDsd-k9zGd7HI4hwfxjwM5uOLjCJF_zQUVzFgToJIFjYiGic8HrWVztbYSBuWQqlXXkWNCm86SjShwZTFeb0a2d/s400/eq_18-22_.png" width="400" /></a></div>
<br />
<br />
Equations (20) and (21) constitute a pair of
simultaneous linear integral equations in <span style="color: blue;"><i>x_dot_dot(t)</i></span>,
i.e., the function to be determined, <span style="color: blue;"><i>x_dot_dot(t)</i></span>, appears
under integral signs in Eqs. (20) and (21). The solution
of Eqs. (20) and (21) for <span style="color: blue;"><i>x_dot_dot(t)</i></span> is not simple
since they do not even uniquely determine <span style="color: blue;"><i>x_dot_dot(t)</i></span>.
Since <span style="color: blue;"><i>x_dot_dot(t)</i></span> is a function of time, it has infinitely
many degrees of freedom and hence there are an infinite
number of <span style="color: blue;"><i>x_dot_dot(t)</i></span>'s which satisfy Eqs. ( 20) and
(21). These equations can uniquely determine an
<span style="color: blue;"><i>x_dot_dot(t)</i></span> however, if some other suitable condition is
also imposed. The most suitable additional condition to
impose is the requirement that
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaIBfUfU_ANj7gvY1epqx90aNME1AibmZykljVL40QwLCr2hu3V67J6rr4TrW6mCZifdquAB22CY5FE9jGV5O2GdqnCj1PxzsqMrAfFIrqf9pp2yY7gTl0VNFdoSsNpfGP-3L6woR1efCT/s1600/eq_23.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="50" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhaIBfUfU_ANj7gvY1epqx90aNME1AibmZykljVL40QwLCr2hu3V67J6rr4TrW6mCZifdquAB22CY5FE9jGV5O2GdqnCj1PxzsqMrAfFIrqf9pp2yY7gTl0VNFdoSsNpfGP-3L6woR1efCT/s320/eq_23.png" width="320" /></a></div>
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<br />
This condition, however, involves a calculus of variations
problem whose solution requires extensive numerical
procedures. It is desired to find a solution which is
explicit, or analytical. The approach is deliberately to
limit the number of degrees of freedom of the <span style="color: blue;"><i>x_dot_dot(t)</i></span>
which can be used for the solution function. Since Eqs. (20)
and (21) regarded as an algebraic system, can only determine
two constants, it is appropriate to limit <span style="color: blue;"><i>x_dot_dot(t)</i></span> to
two degrees of freedom. This is done by specifying that
<span style="color: blue;"><i>x_dot_dot(t)</i></span> be defined by:
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3-dXKkAjGgFPAmpbZQEPj6EECEhkgXIq1ow5E2Z9jjr-SWUu9kKLyDAPIG3f8CKDQEhzzVFnCCd7AEwizwEPKH_-16syyu9nAvoWmZ5GMFzFvwlk2RJZtQ2pYBCjHMtwbb7gIc-Hx6EcA/s1600/eq_24.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="26" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi3-dXKkAjGgFPAmpbZQEPj6EECEhkgXIq1ow5E2Z9jjr-SWUu9kKLyDAPIG3f8CKDQEhzzVFnCCd7AEwizwEPKH_-16syyu9nAvoWmZ5GMFzFvwlk2RJZtQ2pYBCjHMtwbb7gIc-Hx6EcA/s400/eq_24.png" width="400" /></a></div>
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where <span style="color: blue;"><i>p1(1)</i></span> and <span style="color: blue;"><i>p2(t)</i></span> are any pre-specified, linearly
independent, integrable functions of time, and <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span> are
quantities which are chosen to satisfy Eqs. (20) and
(21). Then <span style="color: blue;"><i>x_dot_dot(t)</i></span> has only two degrees of freedom
because two arbitrary coefficients, <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span>, are
sufficient to determine <span style="color: blue;"><i>x_dot_dot(t)</i></span>. Before <span style="color: blue;"><i>x_dot_dot(t)</i></span>
was limited as in Eq. (24), the function <span style="color: blue;"><i>x_dot_dot(t)</i></span>,
expanded in a general Fourier series, had an infinite number
of undetermined Fourier coefficients, and hence an infinite
number of degrees of freedom.
<br />
<br />
Substituting the two-degree-of-freedom definition of <span style="color: blue;"><i>
x_dot_dot(t)</i></span> into Eqs. (20) and (21) yields:
<br />
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<br />
The coefficients of <span style="color: blue;"><i>c1 </i></span>and <span style="color: blue;"><i>c2 </i></span>in Eqs. (25) and (26),
although written as integrals, are simply algebraic
functions of the current time, <span style="color: blue;"><i>t0</i></span>, and the terminal time, <span style="color: blue;"><i>T</i></span>.
Equations (25) and (26) can be solved for <span style="color: blue;"><i>c1 </i></span>and <span style="color: blue;"><i>c2 </i></span>and a
solution, <span style="color: blue;"><i>x_dot_dot(t)</i></span>, determined. It is required that
<span style="color: blue;"><i>p1(t) </i></span>and <span style="color: blue;"><i>p2(t)</i></span> be linearly independent (that is, <span style="color: blue;"><i>p1(t)</i></span> must
not be a multiple of <span style="color: blue;"><i>p2(t)</i></span> or vice versa) in order to ensure
that the determinant of the algebraic system (Eqs. (25) and
(26)) exists. The actual choice made in specifying <span style="color: blue;"><i>p1(t)</i></span> and
<span style="color: blue;"><i>p2(t)</i></span> will determine the propellant economy of the resulting
steering law. The derivation is completed by specifying that
<span style="color: blue;"><i>x_dot_dot(t)</i></span> be a linear function of time. It is convenient
to define <span style="color: blue;"><i>p1(t)</i></span> and <span style="color: blue;"><i>p2(t)</i></span> as follows:
<br />
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikaHTpV8zDz9RH-F3uPKnbucBpYJ8jfIXvkR3_N7wRcT8MTSWQzSbR9KUap2KSsuQZOU_A_izZ5nbfynvcVirpDYC8rKU-gVF_2-NLZBv9zoP-C5t52dA4UzGDxdFSaN927VGNKIVu6QCI/s1600/eq_27_28.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="70" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikaHTpV8zDz9RH-F3uPKnbucBpYJ8jfIXvkR3_N7wRcT8MTSWQzSbR9KUap2KSsuQZOU_A_izZ5nbfynvcVirpDYC8rKU-gVF_2-NLZBv9zoP-C5t52dA4UzGDxdFSaN927VGNKIVu6QCI/s320/eq_27_28.png" width="320" /></a></div>
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This particular choice for <span style="color: blue;"><i>p1(t)</i></span> and <span style="color: blue;"><i>p2(t)</i></span> approximately
minimizes the integral of the square of the thrust
acceleration, and produces a useful steering law. However.
this choice of <span style="color: blue;"><i>p1(t)</i></span>, and <span style="color: blue;"><i>p2(t)</i></span> is not necessarily final,
and a better choice resulting in better <span style="color: blue;"><i>dV</i></span> performance may
ultimately be made. The data and examples presented in
chapter 2.1 was obtained with the definitions of <span style="color: blue;"><i>p1(t)</i></span> and
<span style="color: blue;"><i>p2(t)</i></span> given in Eqs. (27) and (28).
<br />
<br />
Using the definitions of <span style="color: blue;"><i>p1(t)</i></span> and <span style="color: blue;"><i>p2(t)</i></span> in Eqs. (27) and
(28), the coefficients of <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span> can be determined in
the system of equations, Eqs. (25) and (26). Evaluation
of the integrals in Eqs. (25) and (26) transforms these
equations of constraint into
<br />
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<br />
The determinant of this pair of linear algebraic equations
for <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span> is:
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3wR2GNHCFyy2wEYQCpSucToTUxhW2BKr2qJskkwi5j7MC4i8ji2Rk01vmR3Jq4V1bD0K0Kdghm641w1LYLK5KaXWQMm4szG_oFdunAxLYAw0-eE2GtoRGbPSlZTXGFcGMzOJeDXCOp_Hu/s1600/eq_31.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="29" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg3wR2GNHCFyy2wEYQCpSucToTUxhW2BKr2qJskkwi5j7MC4i8ji2Rk01vmR3Jq4V1bD0K0Kdghm641w1LYLK5KaXWQMm4szG_oFdunAxLYAw0-eE2GtoRGbPSlZTXGFcGMzOJeDXCOp_Hu/s320/eq_31.png" width="320" /></a></div>
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<br />
The solution for <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span>, in matrix notation, is:
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRkXmgfrBDs3AsiyQ5_GK4ZdUomM91brGmT1e6Tll5TP5lvm60w4c0qodD2KRid7ZPLFmxmOBwxFxlZJaY_fwCI9epTVsCkZXVLXB2AC8UsmzeBUtWw4Wi0MqgHWRTLA6bWRvqunHBQP94/s1600/eq_32.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="43" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRkXmgfrBDs3AsiyQ5_GK4ZdUomM91brGmT1e6Tll5TP5lvm60w4c0qodD2KRid7ZPLFmxmOBwxFxlZJaY_fwCI9epTVsCkZXVLXB2AC8UsmzeBUtWw4Wi0MqgHWRTLA6bWRvqunHBQP94/s400/eq_32.png" width="400" /></a></div>
<br />
With <span style="color: blue;"><i>c1</i></span> and <span style="color: blue;"><i>c2</i></span> determined from Eq. (32), a solution to the
x-axis boundary value problem is given by:
<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVT8qsnHr8GhZPzg7o989Mte7nJeCL2H153zvDF-fmHuc79nfAAzotrKylQbioQLlStPd2THGsxaR8RFf9Qhjvtp97rLcgF8kbFRT4IlGBAjhiCX5xHMGGA67EAahr3gyCBYPTL3rUMG0V/s1600/eq_33.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="23" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVT8qsnHr8GhZPzg7o989Mte7nJeCL2H153zvDF-fmHuc79nfAAzotrKylQbioQLlStPd2THGsxaR8RFf9Qhjvtp97rLcgF8kbFRT4IlGBAjhiCX5xHMGGA67EAahr3gyCBYPTL3rUMG0V/s320/eq_33.png" width="320" /></a></div>
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<br />
In order to obtain this x-acceleration profile in accordance
with differential Eq. (8), the following equality is
required:
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<br />
Thus the sum of gravitation and thrust acceleration must be
equal to the solution x-acceleration profile, and the
solution thrust acceleration program is:
<br />
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<br />
It is obvious that the same kind of treatment can be given
to the y and z axes. For example:
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<br />
Equations (36) and (37) yield a solution thrust
acceleration program for the y-axis boundary-value problem.
A similar set of equations exists for the z-axis problem.
<br />
<br />
By the method just described, the three components of a
solution thrust acceleration program can be computed. This
procedure of computing the components of the solution thrust
acceleration vector separately is valid because the landing
engine is throttle able. The constraint:
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<br />
is satisfied by commanding a thrust acceleration magnitude
equal to the square root of the sums of the squares of the
components of the thrust acceleration. If the engine were
not throttle able, this simple procedure could not be
implemented.
<br />
<br />
Because the thrust of the LEM descent engine is bounded
between 1050 lbs and 10, 500 lbs, the descent engine cannot
satisfy Eq. (38) under all conditions. The boundary-value
problem must be a feasible one; for example, it cannot be
expected to decelerate the spacecraft from orbital velocity
to zero velocity in 100 miles of range or 200 seconds of
burning time. These kinds of boundary conditions require a
higher thrust than the LEM descent engine is capable of
providing. Note that in the derivation of the steering
equations, the method of determining the terminal time <span style="color: blue;"><i>T</i></span> was
not discussed. Determining <span style="color: blue;"><i>T</i></span> is equivalent to determining <span style="color: blue;"><i>Tgo</i></span>
since the terminal time minus the current time is the
time-to-go. The initial <span style="color: blue;"><i>Tgo</i></span>, i.e., the time-to-go at engine
ignition. is chosen to make <span style="color: blue;"><i>aT</i></span> near the maximum thrust
acceleration which the engine is capable of providing. The
possibility currently exists that the descent engine will be
required to ignite and run at minimum thrust for about 25
seconds at the start of the landing maneuver. The purpose of
the lowered initial thrust setting is to reduce the initial
torque on the vehicle for possible initial C.G. (<a href="https://en.wikipedia.org/wiki/Center_of_mass" target="_blank">Center of Gravit</a>y) offsets
until the descent engine trim gimbals can be reoriented.
This initial period of lowered thrust is not conceptually
important to the development and operation of the guidance
scheme and consequently is not dealt with in this section.
The actual computation of the initial <span style="color: blue;"><i>Tgo</i></span> is discussed in
chapter 2.4. After initial <span style="color: blue;"><i>Tgo</i></span>, or equivalently <span style="color: blue;"><i>T</i></span>, is
determined, the time-to-go at any subsequent time can be
determined by subtracting the current time from the already
established terminal time.
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>2.3 Guidance Equation Summary</b></span>
<br />
<br />
A particularly economical statement of the guidance
algorithm, which exploits the vector-matrix instructions
available in the LGC (L(E)M Guidance Computer or AGC, Apollo Guidance Computer) interpreter, can be developed. A
certain matrix, called the <span style="color: blue;"><i>E</i></span> matrix, is fundamental to this
statement. The <span style="color: blue;"><i>E</i></span> matrix gives the explicit guidance
technique its name, <u><i>E Guidance</i></u>.
<br />
<br />
The following matrices and row vectors are defined:
<br />
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<br />
In order to clarify the declaration in Eq. (40), the first
row of the S matrix is the row vector (array) <span style="color: blue;"><i>v_vec_D</i></span> minus
the row vector <span style="color: blue;"><i>v_vec_0</i></span>. Furthermore:
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<br />
In terms of the foregoing symbols and definitions, the
desired or solution thrust acceleration vector is given by:
<br />
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<br />
Figure 8 repeats these computational steps in block
format.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUG4rAYhliq3Ks8ZIkkH2-6N6RVL_PI6WsRLOISSWUb6WupK7h_jPKz70JjcWYKy2vQ0fkWlrcdkoYJGOTYcMgRKJqV6h4sdoR-Ru_03GJ6Qw4qp1iqWT1BmmbIEvTtqSbFQEc6PBfhwz8/s1600/Fig_4_8.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUG4rAYhliq3Ks8ZIkkH2-6N6RVL_PI6WsRLOISSWUb6WupK7h_jPKz70JjcWYKy2vQ0fkWlrcdkoYJGOTYcMgRKJqV6h4sdoR-Ru_03GJ6Qw4qp1iqWT1BmmbIEvTtqSbFQEc6PBfhwz8/s400/Fig_4_8.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 8. E Guidance steering equations.</span></i></span></td></tr>
</tbody></table>
<br />
Equation (44) can be verified by performing the
matrix multiplications and comparing the result with Eqs.
(32), (35), (36) and (37). In particular:
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It might be noted that if the navigation system were
perfect, and the LEM's SCS and flight-control System's
execution of the guidance commands perfectly implemented.
the matrix <span style="color: blue;"><i>C</i></span> would be a constant throughout the entire
powered flight phase. Even with physical systems and their
associated performance limits the elements of the <span style="color: blue;"><i>C</i></span> matrix
change slowly. Thus the <span style="color: blue;"><i>C</i></span> matrix can be computed at a
relatively low computation rate. The elements of the <span style="color: blue;"><i>g_vec</i></span>
vector, the gravitational acceleration, also evolve slowly.
Consequently, the desired thrust acceleration vector can be
computed for many seconds without re-computation of <span style="color: blue;"><i>C</i></span> and <span style="color: blue;"><i>g</i></span>.
A minor computation loop, involving merely the following
computation steps, can thus be established:
<br />
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<br />
This minor computation loop is particularly important as
time-to-go approaches zero, for then the four non-zero
elements of <span style="color: blue;"><i>E</i></span> increase without bound and the <span style="color: blue;"><i>C</i></span> matrix, which
is the product of <span style="color: blue;"><i>E</i></span> and <span style="color: blue;"><i>S</i></span>, "<span style="color: purple;"><span style="background-color: white;"><i>blows up</i></span></span>". This "<span style="color: purple;"><i>blowing up</i></span>" of
the <span style="color: blue;"><i>E</i></span> and <span style="color: blue;"><i>C</i></span> matrices is due to the fact that as <span style="color: blue;"><i>Tgo</i></span> becomes
vanishingly small, the negligible but non-vanishing errors
in the boundary conditions require an infinite thrust
acceleration for their correction. The wild behavior of <span style="color: blue;"><i>C</i></span> is
avoided by the simple expedient of not computing <span style="color: blue;"><i>E</i></span>, <span style="color: blue;"><i>S</i></span> and <span style="color: blue;"><i>C</i></span>
during the last few seconds of the powered maneuver.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1wp98YodUVbn3903QTKhMAUm_nfI1WQ0xZE3hv5OO_ouQKc73bGnQ6cSyXQu0RNek6gsVWd35ebSX2c_RkL_4JH0LnsERulvQj385uIw-54bsw9zjKU-KKtUtGVI6jA8oE9810AirIwqx/s1600/Fig_4_9.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh1wp98YodUVbn3903QTKhMAUm_nfI1WQ0xZE3hv5OO_ouQKc73bGnQ6cSyXQu0RNek6gsVWd35ebSX2c_RkL_4JH0LnsERulvQj385uIw-54bsw9zjKU-KKtUtGVI6jA8oE9810AirIwqx/s400/Fig_4_9.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 9. Landing powered flight guidance system.</span></i></span></td></tr>
</tbody></table>
<br />
Figure 9 is a block diagram of the landing guidance
system. This diagram shows a block in the LGC which operates
on the desired thrust acceleration vector in order to
produce commands suitable for interpretation by the LEM
flight control system. It is in this block, for example,
that an increment or decrement in thrust magnitude is
computed. The computation of the delta thrust magnitude
command requires an estimate of the vehicle mass in order to
scale the thrust acceleration magnitude error to thrust
change. Thus
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The i subscript refers to the instant of the first engine
ignition. Since the IMU accelerometers perform one
integration, the computation of <span style="color: blue;"><i>dV</i></span> can be mechanized by
summing the square root of the sum of the squares of the IMU
accelerometer (<i>PIPA</i>) outputs. The Computation of the vehicle
orientation commands can proceed in a manner similar to that
used in the CSM. The minor computation loop, Eqs. (46)
and (47), can be used in a relatively fast computation
cycle in the inner steering loop in Fig. 9.
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</div>
<br />
The major computation cycle, Eqs. (39) through (44),
closes the guidance loop through the navigation data. This
major cycle, which includes the computation of a new <span style="color: blue;"><i>C</i></span>
matrix, is depicted in Fig. 9 as an outer loop.
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>2.4 Determination of T or Tgo
</b></span><br />
<br />
In the discussion of the algorithm for computing the
solution thrust acceleration vector, the determination of
the choice of <span style="color: blue;"><i>Tgo</i></span> was not described. Equations (39) through
(44) produce a thrust acceleration regime for any <span style="color: blue;"><i>Tgo</i></span>.
While this solution, <span style="color: blue;"><i>aT,D</i></span>, exists mathematically for any
given <span style="color: blue;"><i>Tgo</i></span>, these solutions are not all physically acceptable
or even physically possible. For example, it should be
evident that for any given boundary-value problem there
exist times-to-go so short that the spacecraft must undergo
extreme accelerations in order to achieve the desired
boundary conditions by the terminal time. These
accelerations require thrust levels which exceed the maximum
thrust capability of the engine. Thus, a very small <span style="color: blue;"><i>Tgo</i></span> must
be avoided, unless the errors in the boundary conditions are
correspondingly small.
<br />
<br />
There are, of course, many more physically impossible
boundary-value problems when the spacecraft is fuel and
thrust-limited. There are boundary-value problems for which
no appropriate <span style="color: blue;"><i>Tgo</i></span> exists. For purely physical reasons,
these problems have no useful or practical solution. In
order to illustrate the landing maneuver phase 1
boundary-value problem, the following example is described.
Consider a fuel-limited, thrust-limited spacecraft which is
moving very fast toward point B from point A. Suppose the
final boundary conditions are that the vehicle must arrive
at point B and possess zero velocity upon its arrival.
Because the spacecraft is moving very fast toward B and has
only a limited thrust acceleration capability, it is
impossible to decelerate the vehicle before its arrival at
point B. Thus, the obvious solution is impossible because of
the limited thrust. Mathematical solutions requiring very
large thrust, nevertheless exist. Now consider a solution in
which the spacecraft passes through or past point B and
returns. Since the vehicle cannot decelerate to zero speed
before its first arrival at point B, application of maximum
thrust will only slow it down. The spacecraft will, of
course, pass by point B and finally stop. After the vehicle
stops, the thrust can be used to start the vehicle moving
back toward point B and, at some point in the vehicle's
return to B, the thrust can be reversed in order to
decelerate the spacecraft before its final arrival at B.
While the program just described for bringing the spacecraft
to rest at B can be arranged to stay below the engine's
maximum thrust level, it should be evident that such thrust
vector programs may easily use all the propellant in the
fuel-limited vehicle. Thus, both solutions, the one in which
the vehicle decelerates and stops at B on its first
approach, and the solution in which the vehicle goes past B,
slows down, returns to B and then steps on its second
approach, are physically useless although mathematically
existent. The first solution is impossible because of the
limited thrust; the second solution is impossible because of
the limited fuel. There is no choice of <span style="color: blue;"><i>Tgo</i></span> which can help
with this kind of boundary-value problem.
<br />
<br />
Now consider how the hypothetical boundary-value problem can
be initiated for a practical solution. The problem is to
find a physically realizable thrust acceleration regime
which will decelerate the vehicle by the time it arrives at
B. If the spacecraft goes too fast toward B, the
thrust-limited rocket cannot decelerate the spacecraft
before its first arrival at B, and thus - there is not
enough fuel to fly past B, stop, and return to B. It can
further be concluded that there is a mathematical solution
for this problem for any given <span style="color: blue;"><i>Tgo</i></span>, although there is no
physically realizable solution for any <span style="color: blue;"><i>Tgo</i></span>. The reason that
the first obvious mathematical solution is impossible is
that point A is so close to B (close with respect to the
velocity of the vehicle toward B) that the thrust-limited
racket cannot decelerate the vehicle to zero speed by the
time of its arrival at B. If the rocket engine is ignited
earlier so that the distance from ignition-point to B is
greater, the thrust-limited rocket may be able to decelerate
the vehicle to zero speed before its first arrival at B.
Assume that an initial distance or range exists which
permits a solution to the boundary-value problem of arriving
at B the first time with zero velocity for a thrust-limited
vehicle. When the landing engine ignition is delayed until
the spacecraft is at an A point (too close to B), there are
no physical solutions. When the landing engine is ignited at
a point A' further away (than the distance AB) there are
physically realizable solutions corresponding to an interval
of times-to-go. The problem is then to choose from within
this interval of feasible times-to-go a <span style="color: blue;"><i>Tgo</i></span> which is best.
Since there is an interval of feasible A's the best A' also
must be determined. A method for determining the best point
for the engine ignition must be developed as well as a best
initial <span style="color: blue;"><i>Tgo</i></span> (powered flight duration). The determination of
a best A' will lead to the development of an engine ignition
algorithm.
<br />
<br />
The hypothetical boundary-value problem just discussed is
quite similar to the phase 1 boundary-value problem. Point
A' is analogous to the point of phase 1 descent engine
ignition, which is near the perilous of the descent
trajectory and about 12.5° central angle before the
hover point. Point B is analogous to the terminal point of
phase 1. The phase 1 terminal point speed, however, is not
zero. This latter fact does not, of course, invalidate the
qualitative conclusions drawn. During the phase 1 maneuver,
the Spacecraft is decelerated from a velocity of over 5500
ft/sec to a velocity under 1000 ft/sec.
<br />
<br />
Examination of Eqs. (39) through (44) shows that the
components of the desired thrust acceleration vector are
functions of <span style="color: blue;"><i>Tgo</i></span>. Thus, if <span style="color: blue;"><i>Tgo</i></span> is varied while the boundary
conditions are held fixed, all the components of the desired
thrust acceleration vector vary. Consequently, the thrust
angle and the thrust acceleration magnitude change as <span style="color: blue;"><i>Tgo</i></span> is
varied. Figure 10 shows the variation of thrust magnitude
with <span style="color: blue;"><i>Tgo</i></span> for ignition of the engine at the perilune point.
Note that there are three distinct points for which the
thrust magnitude is 10,400 pounds.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEji14cJUYjyYimOl5FVfkGPdII7pOZ3i9DeTuajdWBXrm5GfNwrUAZ-qadGEdYn0eqNYtsqLEQwsRUumfRWy_PpYWbKpEbQA3MD4INtn5xLs9wwjyPB9L-zqOfb8W7vUxiStNl25MKT3Bj3/s1600/Fig_4_10_ThI_vs_Tgo.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEji14cJUYjyYimOl5FVfkGPdII7pOZ3i9DeTuajdWBXrm5GfNwrUAZ-qadGEdYn0eqNYtsqLEQwsRUumfRWy_PpYWbKpEbQA3MD4INtn5xLs9wwjyPB9L-zqOfb8W7vUxiStNl25MKT3Bj3/s400/Fig_4_10_ThI_vs_Tgo.png" width="376" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 10. Initial thrust versus initial Tgo for lunar landing.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
For phase 1, <span style="color: blue;"><i>Tgo</i></span> is chosen to make the initial thrust nearly
maximum. Two reasons exist for choosing time-to-go in this
manner. First, good <span style="color: blue;"><i>dV</i></span> performance can be achieved this way;
and second the thrust tends to decay as the vehicle
decelerates and approaches the phase 1 terminal boundary
conditions. (See Fig. 5 for typical thrust magnitude
behavior during phase 1.) It is desirable to have the thrust
magnitude decay as the spacecraft descends because radar
altimeter information becomes available at about 20,000 feet
altitude and is used to update the spacecraft's current
altitude vector. The updated altitude vector modifies the
boundary-value problem posed to the guidance system. The
new boundary-value problem may require a higher thrust if
the terminal boundary conditions are to be achieved. Because
the thrust magnitude has decayed from maximum during the
first part of the maneuver, a margin exists for increasing
the commanded thrust if such an increase is required. It is
important to note that if the engine ignition is delayed
until the vehicle is too close to the terminal position
vector, the required thrust magnitude, which is initially
set to nearly maximum, will subsequently increase.
<br />
<br />
It was stated that <span style="color: blue;"><i>Tgo</i></span> is chosen to make the initial thrust
magnitude near the maximum thrust level of the engine.
Figure 10 shows the interesting fact that as <span style="color: blue;"><i>Tgo</i></span> is
increased from a very small value to a very large value, the
initial thrust magnitude passes through the maximum thrust
level of the engine three times. Only point (2) of this
figure corresponds to the desired thrust vector regime,
however. Point (1) on Fig. 10 corresponds to such a short
<span style="color: blue;"><i>Tgo</i></span> that the spacecraft must initially be accelerated toward
the terminal point, point B, in order to arrive there at the
stipulated time. For very short time-to-go, the acceleration
toward point B is immense as shown by the very sharp
increase of thrust as <span style="color: blue;"><i>Tgo</i></span> is decreased below 300 seconds.
The trajectory corresponding to point (1) requires that the
thrust vector initially point toward B and finally point
away from E in order to decrease the vehicle's speed before
its arrival. This speeding up and slowing down of the
spacecraft with the thrust vector is, of course,
uneconomical. More than that, even if the fuel were
available for such wasteful efforts, the thrust magnitude
increases as the vehicle proceeds toward B because high
thrust is required in order to decelerate the very rapidly
moving spacecraft before its arrival at B. Therefore, point
(1) is rejected.
<br />
<br />
Point (2) on Fig. 10 corresponds to the desired thrust
vector regime. The thrust angle and thrust magnitude plots
in Figs. 4 and 5 were obtained by choosing the <span style="color: blue;"><i>Tgo</i></span>
corresponding to point (2) on Fig. 10. For this choice of
initial time-to-go, the spacecraft is continually and
efficiently decelerated while the thrust magnitude gradually
decays.
<br />
<br />
The trajectory corresponding to point (3) of Fig. 10
requires a <span style="color: blue;"><i>Tgo</i></span> of about 1800 seconds. In order to expend
this time. the vehicle must first climb in altitude, pass
over the desired terminal point B, decelerate to zero
velocity and then finally re approach point B with the
specified velocity vector. This solution is mathematically
possible, but obviously impractical.
<br />
<br />
The actual computation of the initial <span style="color: blue;"><i>Tgo</i></span> is performed by a
technique which guarantees that point (2) on Fig. 10 is
chosen. A guess at <span style="color: blue;"><i>Tgo</i></span>, call it <span style="color: blue;"><i>T_tilde_go</i></span>, which is
definitely in excess of the required (but unknown) <span style="color: blue;"><i>Tgo</i></span>, is
made. A safe and reasonable value would be 450 Seconds.
The thrust magnitude corresponding to <span style="color: blue;"><i>T_tilde_go</i></span> is examined.
The first value of the computed thrust will, of Course,
exceed 10,400 pounds. The initial time-to-go, <span style="color: blue;"><i>T_tilde_go</i></span>, is
then decremented and the corresponding thrust magnitude
computed and examined. A reasonable decrementing step would
be 10 Seconds. The process of decrementing <span style="color: blue;"><i>T_tilde_go</i></span> and
computing and examining the corresponding thrust magnitude
is continued until a <span style="color: blue;"><i>T_tilde_go</i></span> for which the required thrust
is less than 10,400 pounds is found. The required value of
<span style="color: blue;"><i>Tgo</i></span> is known to lie between this <span style="color: blue;"><i>T_tilde_go</i></span> and the previous
value of <span style="color: blue;"><i>T_tilde_go</i></span> . The method of false position (regula
falsi, Ref l) is then used to find the exact value of <span style="color: blue;"><i>Tgo</i></span>
which makes the thrust equal to 10,400 pounds. Examination
of Fig. 10 will show that this method of computing <span style="color: blue;"><i>Tgo</i></span>
avoids the mischance of choosing points (1) or (3).
<br />
<br />
Specifying the initial time-to-go is equivalent to
specifying the terminal time, <span style="color: blue;"><i>T</i></span>. After <span style="color: blue;"><i>T</i></span> is chosen, the <span style="color: blue;"><i>Tgo</i></span>
corresponding to any subsequent instant of powered flight,
<span style="color: blue;"><i>t0</i></span>, can be found as follows:
<br />
<br />
<b><span style="font-size: small;"><i>Tgo</i> = <i>T</i> - <i>t0</i></span></b>
<br />
<br />
The exception to this is during the last part of phase 2
when landing radar information modifies the boundary-value
problem. It may be advisable to recompute <span style="color: blue;"><i>Tgo</i></span> if a
substantial modification of the boundary-value problem
occurs.
<br />
<br />
The duration of phase 2 is not computed in flight. Since the
phase 2 boundary-value problem is fairly Well standardized
by the conduct of the phase 1 boundary-value problem, a
standard pre-determined initial <span style="color: blue;"><i>Tgo</i></span> can be used for phase 2.
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>2.5 The Engine Ignition Algorithm
</b></span><br />
<br />
It has been concluded in the previous section that the
initial <span style="color: blue;"><i>Tgo</i></span> should be chosen to maximize the initial thrust
level. The implications of requiring an initial period of
thrusting at a reduced level will be discussed later. Figure
11 is a plot of the total <span style="color: blue;"><i>dV</i></span> required to achieve the phase 2
terminal conditions versus the initial range-to-go.<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlHTeFRLKVP868CsHguZXF375YYaVVBMkfvF1FdXEGb7SNhs-b4abyXECT0VHuVe9WlMABufAMdL15YwFntWks_FAGEeYTeYA2pk-sDTpsoBNB-lk5aoYyqUORRxxhbjzNnldChVnESY8a/s1600/Fig_4_11.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjlHTeFRLKVP868CsHguZXF375YYaVVBMkfvF1FdXEGb7SNhs-b4abyXECT0VHuVe9WlMABufAMdL15YwFntWks_FAGEeYTeYA2pk-sDTpsoBNB-lk5aoYyqUORRxxhbjzNnldChVnESY8a/s400/Fig_4_11.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 11. dV required vs. range-to-go.</span></i></span></td></tr>
</tbody></table>
<br />
The
phase 2 terminal conditions are desired hover conditions.
The examples presented in this section assume phase 2
terminal conditions of 200 feet altitude, 10 ft/sec speed,
and -10° flight path angle. The data for Fig. 11 was
generated as follows. A simulation was set up which
permitted the vehicle to be guided from the perilous of the
<a href="https://en.wikipedia.org/wiki/Hohmann_transfer_orbit" target="_blank">Hohmann descent orbit</a> through phase 1 and phase 2 to the
specified hover conditions. The descent-to-hover was
repeatedly simulated. Each Simulation was performed with the
perilune of the Hohmann descent orbit located at a different
angular range-to-go from the specified hover point. The <span style="color: blue;"><i>dV</i></span>
for each case was recorded and Figure 11 generated. Each
simulation used an initial <span style="color: blue;"><i>Tgo</i></span> which set the initial thrust
level to 10,400 pounds. If the perilune point (the point at
which the engine was always ignited in this simulation) was
farther from the hover point than 11.8°, the thrust
magnitude decayed from the maximum at which it Was initially
set. Thus, all the trajectories to the left of <span style="color: blue;"><i>theta_crit</i></span> in
Fig. 11 are physically realizable with the LEM's
thrust-limited descent engine. But when the perilune point
is located closer to the hover point than 11.8°, the
commanded thrust subsequently increases. In this simulation,
the thrust magnitude was not bounded. The <span style="color: blue;"><i>dV</i></span> curve's
excursion into the shaded region of Fig. 11 shows that if
the LEM had higher thrust capability, the landing maneuver
could be performed more economically. The trajectories
corresponding to large initial range-to-go have a long phase
1 which is performed at a lower average thrust level. Such
trajectories are less efficient than those corresponding to
short initial range-to-go (about 12°). It appears that the
Hohmann descent orbit injection should be so arranged that
its perilune is located about 12° before the desired hover
point. and so that the LEM engine should be ignited at the
perilune position. The objection to specifying the standard
engine ignition position at <span style="color: blue;"><i>theta_crit</i></span> is that if the engine
ignition were delayed by even a second or two, the landing
could not be performed due to the fact that greater than
maximum thrust would be required. The perilune of the
Hohmann descent orbit should therefore be located about
12.5° before the hover point, and the perilune point
selected as the standard ignition point. This procedure
gives an engine ignition window of almost 10 seconds with a
<span style="color: blue;"><i>dV</i></span> penalty, if the engine actually ignites at the standard
engine ignition point of about 13 ft/sec.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtd-4Ivn2PSFPNQC44pTMtWXIJImvHWwWrXUVExOM6H0U1DGIrWut9V-HcwDMyecgDsL3aeqg7zyrzfGo7jZYyVTmTaABxfvgWnwHJxTkMrG5SDwXzZXEd6W-NRrwh4gtIwCynyNfz9G6c/s1600/Fig_4_12.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtd-4Ivn2PSFPNQC44pTMtWXIJImvHWwWrXUVExOM6H0U1DGIrWut9V-HcwDMyecgDsL3aeqg7zyrzfGo7jZYyVTmTaABxfvgWnwHJxTkMrG5SDwXzZXEd6W-NRrwh4gtIwCynyNfz9G6c/s400/Fig_4_12.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 12. Engine ignition algorithm for specified landing site.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figures 12 and 13 give an engine ignition algorithm for
the landing maneuver.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-8DuUvz7ZfvaUFJgvOy3zPxfemr3lvI7rApqc8cqdWyYxzr8j9w6igoli0Gp5CFYpz4k1sytxS1r5J6CMPLGTnRy27TOsTs88CFzNBAyUzIjVLgCnryk1PEwZd4f6y81GO5Dpc8onLoy9/s1600/Fig_4_13.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-8DuUvz7ZfvaUFJgvOy3zPxfemr3lvI7rApqc8cqdWyYxzr8j9w6igoli0Gp5CFYpz4k1sytxS1r5J6CMPLGTnRy27TOsTs88CFzNBAyUzIjVLgCnryk1PEwZd4f6y81GO5Dpc8onLoy9/s400/Fig_4_13.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 13. Definition of symbols for engine ignition algorithm (in figure 12).</span></i></span></td></tr>
</tbody></table>
<br />
Because the engine will probably have
to be run at reduced thrust for the first 25 seconds or so
of the landing maneuver, the engine ignition (and perilune
point) will have to be biased by an angle <span style="color: blue;"><i>theta_COMP</i></span>. There
will be, of course, a small <span style="color: blue;"><i>dV</i></span> penalty due to this
requirement to operate the engine at lowered thrust for the
initial seconds of the maneuver. No other difficulty is
anticipated from this source.
<br />
<br />
During the period of thrusting at a reduced level, the
thrust vector orientation computation is performed as though
maximum thrust were being used. Consequently, no thrust
angle discontinuity occurs in the transition from the low
thrust setting to the maximum thrust setting. During the
period of thrusting at a low level, the <span style="color: blue;"><i>C</i></span> matrix behaves
oddly, but no effects of any consequence occur.
<br />
<br />
Note that if the spacecraft is closer to the hover point
than <span style="color: blue;"><i>theta_MIN</i></span> where:
<br />
<br />
<b><span style="font-size: small;"><i>theta_MIN = theta_CRIT + theta_UL + theta_COMP</i></span></b>
<br />
<br />
the spacecraft <u>cannot</u> stop at the proposed hover point and
landing site. If a landing site further downrange were
acceptable, the landing maneuver could still be initiated,
assuming that the inordinate delay for engine ignition is
not due to a cause which necessitates aborting the landing
altogether.
<br />
<br />
Performing the descent orbit injection with the objective of
placing the descent orbit perilune at the nominal engine
ignition point seems a wise course of action because there
are no first order changes in the vehicle's velocity vector
due to perturbations in the location of the perilune. Thus,
the initial conditions for phase 2 are insensitive (to the
first order) to the actual location of the descent orbit
perilune. Because of this phenomenon, fairly long delays in
the initiation of the descent orbit maneuver are acceptable.
Figure 14 summarizes the effects which the descent orbit
injection delay has on the landing maneuver.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPbAzgw0FZ1HAX2edI3BbxpXvc9Y-eh87vldSR7bA6X9WtcMhLYUBt7t9MXRqghdZUz4EqSLqmxTMT-yBgE2Vq8b9su_aADxpxXsSWnWWta7rvTt1n86oHN_OS41aGiJbh_bqWswzIdKkA/s1600/Fig_4_14.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgPbAzgw0FZ1HAX2edI3BbxpXvc9Y-eh87vldSR7bA6X9WtcMhLYUBt7t9MXRqghdZUz4EqSLqmxTMT-yBgE2Vq8b9su_aADxpxXsSWnWWta7rvTt1n86oHN_OS41aGiJbh_bqWswzIdKkA/s400/Fig_4_14.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 14. Effect of delaying engine ignition.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Note that a
delay of 60 seconds is tolerable. Thus the engine ignition
window for the landing maneuver is an order of magnitude
smaller than the engine ignition window for the descent
orbit injection maneuver.
<br />
<br />
<br />
<br />
<h4>
3 Landing Maneuvers from Hohmann Descents
</h4>
<br />
The characteristics of a typical landing maneuver trajectory
controlled by the E guidance equations of Section 2 are
summarized in Figs. 15 through 23.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBIyLT37B0SRes_srNwIzaUJ4sQftIfo_JhpG6jr6Gv_9Wdl0ObT0cNuBoL9vxBBoejdSoDjj3bo1kpTxuBjMJSvXhjvvycD_Pf4S1JGvQvIdU32PX0E_8AaJ3JKickxEHz-fx9lx3ESyW/s1600/Fig_4_15.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBIyLT37B0SRes_srNwIzaUJ4sQftIfo_JhpG6jr6Gv_9Wdl0ObT0cNuBoL9vxBBoejdSoDjj3bo1kpTxuBjMJSvXhjvvycD_Pf4S1JGvQvIdU32PX0E_8AaJ3JKickxEHz-fx9lx3ESyW/s400/Fig_4_15.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 15. Landing maneuver from Hohmann orbit.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 15 illustrates the
altitude-range profile for the first two phases of the
landing maneuver initiated from a Hohmann descent orbit.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE04M1V76ook18wpvzpn4GAf_zb60BrQu2hljasoFQYcpQ30_oUyW0Sj93Lve3gYUq9kj1UobXsibiZ0UcrfbfvMgftEIl8tO6d423YN0L2LJ86m2DLULqijBBTbguk9Kl4PYRDe-xT1Vk/s1600/Fig_4_16.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiE04M1V76ook18wpvzpn4GAf_zb60BrQu2hljasoFQYcpQ30_oUyW0Sj93Lve3gYUq9kj1UobXsibiZ0UcrfbfvMgftEIl8tO6d423YN0L2LJ86m2DLULqijBBTbguk9Kl4PYRDe-xT1Vk/s400/Fig_4_16.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 16. Altitude vs. miles-to-go.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figure 16 shows the plume 2 characteristics which were
chosen such that acceptable visibility conditions were met.
(Figures 4 and 5 show the thrust magnitude and angle for
this trajectory.)<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmY8k0OuRxO17j_YbdH3FUznC-T0pSIwR-hJih8Wl-m_t-S65-sDtx-x9l0AMAqwk1KkBdC64ih0xxG8qRUhHuVQaTSdz39gbaM2bjnALGy3GL93Cufnu7IBed3Ddd_FENiLGJdR3WfaQe/s1600/Fig_4_17.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmY8k0OuRxO17j_YbdH3FUznC-T0pSIwR-hJih8Wl-m_t-S65-sDtx-x9l0AMAqwk1KkBdC64ih0xxG8qRUhHuVQaTSdz39gbaM2bjnALGy3GL93Cufnu7IBed3Ddd_FENiLGJdR3WfaQe/s400/Fig_4_17.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 17. Altitude vs. time (sec.).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Figures 17 through 20 summarize the
general landing maneuver position and velocity conditions as
a function of time.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhppGq2U8Ci0oVH9H04SzMqtQL8Iy3ubFv6WmSPmmUhkZX86GZwhtz1sMHIz0k0vpzHcId-QlqDBeooJ83n-8vbr2etgBI8yNfKX0y5TFwdbFKfMkMxJPBasjLDXsTHEAWo-mKZ2IlGY45b/s1600/Fig_4_18.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhppGq2U8Ci0oVH9H04SzMqtQL8Iy3ubFv6WmSPmmUhkZX86GZwhtz1sMHIz0k0vpzHcId-QlqDBeooJ83n-8vbr2etgBI8yNfKX0y5TFwdbFKfMkMxJPBasjLDXsTHEAWo-mKZ2IlGY45b/s400/Fig_4_18.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 18. Range-to-go (x) vs. time (t) (sec.).</span></i></span></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUkA_rRtCW7QIoalx1D6Y1N4VsaFau6waIXgiGioC2eL96eKKwZfrR9XQk1aM_6C43-dK8-glZnutbMk2jK6xfXAjPfzjEnij42o32bOW5uVBdEDVla3O37sTwBo-WErAr04hn7r842Eqa/s1600/Fig_4_19.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiUkA_rRtCW7QIoalx1D6Y1N4VsaFau6waIXgiGioC2eL96eKKwZfrR9XQk1aM_6C43-dK8-glZnutbMk2jK6xfXAjPfzjEnij42o32bOW5uVBdEDVla3O37sTwBo-WErAr04hn7r842Eqa/s400/Fig_4_19.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 19. Speed vs. time (sec.).</span></i></span></td></tr>
</tbody></table>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfjaOdOIeSFiC4bO9RYp8J5CwaVD3RBuJuEdXITP5vxCR7O4qRwy3AopnPfhyZEWu7lFbJ606s8YhCYRpeKYjRr9MbXQSfULIexS14hVR-__baemV-PpMVd1qxqE2nkSmGEkcQ1hNqm7tI/s1600/Fig_4_20.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfjaOdOIeSFiC4bO9RYp8J5CwaVD3RBuJuEdXITP5vxCR7O4qRwy3AopnPfhyZEWu7lFbJ606s8YhCYRpeKYjRr9MbXQSfULIexS14hVR-__baemV-PpMVd1qxqE2nkSmGEkcQ1hNqm7tI/s400/Fig_4_20.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 20. Altitude rate (vertical speed) vs. time (sec.).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
With reference to Fig. 20, it can be
seen that the maximum vertical velocity condition is 180
ft/sec and occurs just prior to the second phase of the
landing maneuver.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpHDPkC8ErxytftvF0dZ1qVrk8cWyfCjBcxPYAmN38GQS1xK-pruy1DCnEo9X-pc2v5FRRgZIdSR6RzV8WLz0l85kUkHKuWAtgK_ZLk0SFngKqOWNHwA64jW7b8-aMYYgfVoY-MMRBrhYe/s1600/Fig_4_21.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpHDPkC8ErxytftvF0dZ1qVrk8cWyfCjBcxPYAmN38GQS1xK-pruy1DCnEo9X-pc2v5FRRgZIdSR6RzV8WLz0l85kUkHKuWAtgK_ZLk0SFngKqOWNHwA64jW7b8-aMYYgfVoY-MMRBrhYe/s400/Fig_4_21.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 21. dV performance summary.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The <span style="color: blue;"><i>dV</i></span> requirements for the first two phases of the landing
maneuver are summarized at the top of Fig. 21. The desired
hover conditions at the end of phase 2 are an altitude of
200 feet with a velocity of 10 ft/sec along a -10° flight
path angle relative to the local horizontal. The total <span style="color: blue;"><i>dV</i></span>
requirement of 6048 ft/sec for these two phases controlled
by the landing guidance equations is then compared with
other types of landing maneuvers and conditions. If a "one
piece" descent from engine ignition to hover is controlled
by the landing guidance equations, a <span style="color: blue;"><i>dV</i></span> of 5805 ft/sec is
required. This indicates that the two phase maneuver with
its associated vehicle altitude and time constraints in
phase 2 requires an additional 243 ft/sec <span style="color: blue;"><i>dV</i></span> requirement
compared with the more optimum single phase maneuver in
which all visibility would be sacrificed. The optimum <span style="color: blue;"><i>dV</i></span>
trajectory listed in Fig. 21 was generated by a numerical
steepest descent optimization program and required 10 ft/sec
less total <span style="color: blue;"><i>dV</i></span> than the single phase E guidance case. This
indicates that the <span style="color: blue;"><i>E</i></span> guidance concept described in chapter 2 is very close to optimum <span style="color: blue;"><i>dV</i></span> conditions for the landing
maneuver.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsF0Bv-aWNPqpJyKLPhjY7RKAursPjcTtBP4TRiTm-y0_ddchUQT3glouDd9qb0Omxrw3LTo9XNGxHcj43x2rNLr8XjA_MZqpf17XRuCLthFBdT8a33NGJaxMrcuzpwZcE3bvyJEUStzzp/s1600/Fig_4_22.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsF0Bv-aWNPqpJyKLPhjY7RKAursPjcTtBP4TRiTm-y0_ddchUQT3glouDd9qb0Omxrw3LTo9XNGxHcj43x2rNLr8XjA_MZqpf17XRuCLthFBdT8a33NGJaxMrcuzpwZcE3bvyJEUStzzp/s400/Fig_4_22.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 22. Look angle vs. time (sec.).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The time history of the look angle during the second phase
of the landing maneuver is shown in Fig. 22. The look angle, <span style="color: blue;"><i>lambda</i></span>, is defined as the angle between the line of sight to
the landing site and the thrust or -x LEM vehicle axis. The
minimum visibility limit of the present LEM window
configuration is 25° as shown. The landing maneuver
considered in this section resulted in a look angle of 32°.
i.e., 7° above the lower edge of the LEM window. The
visibility angle and landing site monitoring during phase 2
are described in detail in another section.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEju1X_-X5hKIY_0VmYTnmmeTusllsTtUV-l7fgQyK-a1NAg_b56uzfFFd3ifPY7QzOkFGtTFWzHs50SuewwDdelQbCjHR-n6qKxM1_nu5cRPciB40-qGgAOrVPOp3UxnTT11_cvKWpd9Lr7/s1600/Fig_4_23.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEju1X_-X5hKIY_0VmYTnmmeTusllsTtUV-l7fgQyK-a1NAg_b56uzfFFd3ifPY7QzOkFGtTFWzHs50SuewwDdelQbCjHR-n6qKxM1_nu5cRPciB40-qGgAOrVPOp3UxnTT11_cvKWpd9Lr7/s400/Fig_4_23.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 23. dV requirements for phase 2 constraints.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The <span style="color: blue;"><i>dV</i></span> penalty associated with various values of the minimum
look angle. <span style="color: blue;"><i>Lambda_MIN</i></span>, during the second phase is summarized
in Fig. 23. Approximately 100 ft/sec additional <span style="color: blue;"><i>dV</i></span> is
required to increase the minimum visibility angle from 26°
to 36° if the phase 2 maneuver time is held fixed at 115
seconds. With reference to Fig. 23, it can be seen that as
the minimum look angle, <span style="color: blue;"><i>lambda_MIN</i></span>, is increased, the phase 2
initial altitude, vertical velocity, and range to go all
decrease, thus lower thrust levels are commanded. These are
desirable effects for astronaut monitoring, but require <span style="color: blue;"><i>dV</i></span>
penalties that make them doubtful.
<br />
<br />
It should be noted that the landing maneuver characteristics
presented in this section assumed a point mass LEM vehicle
and no LEM attitude or throttle system dynamics were
considered. The results of current guidance equation
simulations which include the LEM vehicle dynamics will be
presented in a future report.
<br />
<br />
<br />
<span style="color: #20124d;"><i>[Chapter 4 (Performance Estimations) and chapter 5 (Equal Period Descents) have been skipped. See original paper /1/ if required.]</i></span><br />
<br />
<br />
<h4>
6 Hover and Touchdown Phase.
</h4>
<br />
This final phase of the landing maneuver starts from the
hover conditions established by the previous second or
constant attitude phase of the maneuver. As described in chapter 2, the boundary conditions for the constant
attitude phase are an altitude of 200 feet over the desired
landing site with a velocity in the order of 10 ft/sec or
less. The astronaut has the option of several modes of
operation from these hover conditions. These modes of
operation include a completely manual landing maneuver, a
completely automatic landing maneuver controlled by the
inertial units of the primary GN system, or some
combination of manual and automatic modes to provide a
semi-automatic or pilot assisted landing. The type of
terminal letdown and landing maneuver will depend on the
lunar surface conditions, and how they interact with the
descent engine exhaust gases.
<br />
<br />
Under normal operation, the landing radar updating process
is completed prior to the final letdown maneuver from the
hover altitude. The automatic or semi-automatic modes of
operation are then controlled from the inertial units of the
primary GN system <u>since landing radar data is questionable
if severe dust or debris conditions occur</u> because of
interaction of the exhaust gases with the lunar terrain. The
automatic mode of operation would involve a final landing
radar update at the hover point with the visual check of the
surrounding terrain and horizontal velocity conditions. This
would be followed by a reduced throttle command which would
build up a downward velocity followed by an increased
throttle command to achieve a desired constant vertical
velocity at a given altitude above the lunar terrain. <u>This
final constant velocity letdown would then be maintained by
the inertial system until lunar contact had been made.</u>
<br />
<br />
The semi-automatic mode of operation would be similar to the
above automatic mode with the exception that the astronaut
could interrupt this procedure at any point by an altitude
hold mode of operation. When the astronaut selected this
mode, the LGC would maintain control of the descent engine
throttle servo and maintain a setting that would hold a
constant altitude at the time of pilot control initiation.
The astronaut would have complete control over the LEM
attitude through the attitude controller and by pitching the
vehicle in a desired direction he could effect translation
maneuvers while the LGC maintained the constant altitude by
thrust level control. When the astronaut has performed his
desired translation maneuvers, the automatic system is reengaged, at which time any residual horizontal velocities
are nulled and the automatic descent maneuver reestablished.
<br />
<br />
A hover altitude for the terminal conditions of the second
landing maneuver phase were chosen arbitrarily, but are
estimated to be the minimum altitude at which potential
lunar dust problems would start (Ref. 2). The automatic let
down maneuver from these hover conditions will require
significant <span style="color: blue;"><i>dV</i></span>, depending upon various restrictions placed
on the terminal letdown maneuver. The important parameters
during the terminal letdown and their effects on the overall
<span style="color: blue;"><i>dV</i></span> requirement are summarized in Fig. 56.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnTECxTDS5W_KxYDBkMmhhQsEjUBumb_HoDDhIa3awtEdxskp3GJPUpJMNYmpMpjrfU2BGNTSfEtcn6jRlEmkXN7EcVvCILDHSUjrZYsVgCY4iRBml_OJbJJUC7N6YKT1SBS26hH6cWJ3a/s1600/Fig_4_56.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgnTECxTDS5W_KxYDBkMmhhQsEjUBumb_HoDDhIa3awtEdxskp3GJPUpJMNYmpMpjrfU2BGNTSfEtcn6jRlEmkXN7EcVvCILDHSUjrZYsVgCY4iRBml_OJbJJUC7N6YKT1SBS26hH6cWJ3a/s400/Fig_4_56.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 56. Lunar landing - hover to touchdown (automatic mode).</span></i></span></td></tr>
</tbody></table>
<br />
<br />
In this figure,
the hover condition is assumed to be in an altitude of 200
feet with a zero velocity condition relative to the lunar
surface. The first interval of the descent maneuver
illustrated in the top of Fig. 56 requires reducing the
descent engine throttle until a maximum vertical velocity <span style="color: blue;"><i>V1</i></span>
is achieved. The thrust is then increased so that the
desired terminal descent velocity, <span style="color: blue;"><i>V2</i></span>, is established at
some designated altitude, <span style="color: blue;"><i>h2</i></span>, after which the velocity <span style="color: blue;"><i>V2</i></span> is
maintained until surface contact is made. This operation can
be illustrated by the first example of Fig. 56 in which the
descent engine was throttled to its minimum setting for 5. 3
seconds until the maximum desired sink rate <span style="color: blue;"><i>V1</i></span> of 15 ft/sec
was achieved at an altitude of 160 feet, <span style="color: blue;"><i>h1</i></span>. The thrust of
the descent engine was then increased over the next 9.5
seconds such that the desired terminal contact velocity <span style="color: blue;"><i>V2</i></span>
of 10 ft/sec was established by the time the vehicle reached
an altitude <span style="color: blue;"><i>h2</i></span> of 40 feet. This terminal velocity of 10
ft/sec was then maintained over the next 4 seconds until
lunar surface touchdown was made. The total velocity
requirement for this maneuver was 90.6 ft/sec as shown in
Fig. 56. Fly comparing the various maneuvers Summarized in
this figure with their associated maximum vertical
velocities, <span style="color: blue;"><i>V1</i></span>; terminal contact velocities, <span style="color: blue;"><i>V2</i></span>; and
altitude of the constant velocity phase <span style="color: blue;"><i>h2</i></span>; it can be seen
that the <span style="color: blue;"><i>dV</i></span> requirements range between 70 and 130 ft/sec.
The maneuvers summarized in Fig. 56 are near optimum type
maneuvers for the various descent parameters considered.
Actual maneuvers involving semi-automatic or pilot assisted
landings will obviously require more <span style="color: blue;"><i>dV</i></span> than the near optimum descents summarized in this figure.
<br />
<br />
The primary reason that a hover altitude of 200 feet was
chosen for the examples illustrated in this chapter for
landing maneuvers was that the <span style="color: blue;"><i>dV</i></span> requirement increases for
hover and terminal letdown maneuvers from higher altitudes.
The effect of hover altitude on the <span style="color: blue;"><i>dV</i></span> requirement for the
terminal maneuver is illustrated in Fig. 57.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglzuTUBSJ7ZTgGXDyKXE1KdFs7YlXVlugrFgwM6EW38Vl2QBlHpuVcDoL5evJ-eoxmQMcao3lImHGeHPJUBRaJT2IR5D3qWT_ikwtDlxj1ZFPxSHklKu9hJgovcIXnorZMvnKFUrHsSUNX/s1600/Fig_4_57.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglzuTUBSJ7ZTgGXDyKXE1KdFs7YlXVlugrFgwM6EW38Vl2QBlHpuVcDoL5evJ-eoxmQMcao3lImHGeHPJUBRaJT2IR5D3qWT_ikwtDlxj1ZFPxSHklKu9hJgovcIXnorZMvnKFUrHsSUNX/s400/Fig_4_57.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 57. Characteristic velocity vs. initial altitude for touchdown maneuver.</span></i></span> </td></tr>
</tbody></table>
<br />
<br />
The curves
illustrated in this figure are for the three velocity and
altitude conditions previously considered in Fig. 56. These
are the maximum allowed vertical velocity during the
maneuver, <span style="color: blue;"><i>V1</i></span>; the desired terminal touchdown velocity, <span style="color: blue;"><i>V2</i></span>;
and the altitude <span style="color: blue;"><i>h2</i></span>, at which the constant velocity must be
established. It can be seen from Fig. 57, that all the
conditions shown require essentially 100 ft/sec for
automatic maneuver from 200 foot hover altitudes. As this
hover altitude is increased to 1000 feet, the <span style="color: blue;"><i>dV</i></span>
requirements range from approximately 300 to 500 ft/sec,
depending upon the terminal descent maneuver characteristics
chosen. As previously mentioned, the hover altitude will be
chosen on knowledge of the lunar surface or dust conditions
that are expected. The primary GN mode of operation up to
the hover point condition requires that all final landing
radar updating and astronaut visual monitoring be completed
by the time the terminal letdown maneuver is initiated. The
astronaut will still have the option of interrupted manual
control, pilot assisted landing, if desired after this
point.
<br />
<br />
At the present time. the descent engine cutoff criteria at
the end of the terminal letdown has not been completely
determined. The lunar surface, or dust conditions. and
visibility limitations will be one of the major factors in
determining what thrust termination criteria will be used.
One of two approaches most often considered is to terminate
thrust at an altitude of approximately 5 feet with zero
velocity conditions. The uncertainty involved in this
technique under heavy dust or no visibility conditions is
that knowledge of altitude may not be available from the
landing radar and errors would exist if extensive cratering
was effected by the exhaust of the descent engine. An
alternate approach would maintain the descent engine thrust
until lunar contact had been made at the inertially
controlled terminal velocity <span style="color: blue;"><i>V2</i></span> of Fig. 56 at which time
the thrust would be terminated. This technique would not
depend on landing radar data and would be independent of
cratering effects. The major problem with the latter
technique is the dynamic effects on the LEM if one landing
gear makes contact before the others under a throttle
condition that essentially balances lunar gravity. The final
engine termination criteria will depend on future
simulations and knowledge of the lunar terrain.
<br />
<br />
An alternate method of third phase operation to touchdown is
currently (1964) under investigation. This approach uses the
same guidance concept as phase 2 to maintain visibility to
the landing site as long as possible. The LEM does not came
to a hover condition followed by a vertical descent in this
approach, but the terminal conditions of phase 2 are chosen
so that a near constant attitude can be maintained along a
trajectory similar to that of phase 2 from altitudes of 200
feet to near surface contact. The results of this
investigation are still preliminary and will be presented in
a future report.
<br />
<br />
The primary GN system controls the LEM attitudes about the
vehicle y and z axes throughout all automatically guided
phases of the lunar landing maneuver. The vehicle
orientation about the thrust axis (x axis) may or may not be
controlled by the primary GN system during the first and
third phases of the landing maneuver, but will be controlled
during the second or constant attitude phase of the landing
maneuver as described in another section. During the first
phase of the landing maneuver, the vehicle z axis, may be
directed downward so that the astronauts will be able to see
the lunar surface until an altitude of approximately 30,000
feet is reached. At this time a 180° maneuver about
the x axis is effected so that the window, or z axises in
the up direction prior to the pitch-up on initial point of
the second phase of the landing maneuver. It is important
for primary GN operation that the attitude about the z axis
be such that the windows are up when an altitude of 20,000
feet is reached, so that the landing radar can be used for
updating altitude.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNp_Sl5ZjTS-cC8Hu5uQPcPDKb8L0h9R9OqI79UsELVhRWD_q4WoG6hZMQ3fLmUJ7j4grOJTH2q7NxW7mh3em28CqPBYaD5a2GEgDysukVgEPGYG5rYAGRsZTr4WFW643RlHjyfHd1CHuy/s1600/Fig_1_19.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgNp_Sl5ZjTS-cC8Hu5uQPcPDKb8L0h9R9OqI79UsELVhRWD_q4WoG6hZMQ3fLmUJ7j4grOJTH2q7NxW7mh3em28CqPBYaD5a2GEgDysukVgEPGYG5rYAGRsZTr4WFW643RlHjyfHd1CHuy/s400/Fig_1_19.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Figure 1.19. LEM landing radar antenna positions.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The current landing radar antenna
Configuration is a two position arrangement such that the
altitude measuring beam would be essentially vertical during
the constant attitude phase (Fig l.19). This altitude beam
could be used prior to the constant attitude phase at
altitudes of approximately 20,000 feet. The second position
of the landing radar antenna would be such that the altitude
measuring beam would be vertical when the vehicle is in a
vertical orientation at the hover conditions.
<br />
<br />
There is no primary GN system requirement for a preferred
orientation of the LEM about the x axis at the time of lunar
surface contact. The rendezvous radar gimbal axes have
sufficient coverage to insure CSM tracking over the desired
tracking sector (Section 5.3) under virtually any landing
orientation. The three position AOT can achieve IMU
alignments if the sun or earth are in the field of view for
one fixed AOT position. The primary GN system places no
restriction on the final touchdown orientation; however, if
a choice is available it is preferred to direct the three
positions of the AOT away from the sun or illuminated earth.
<br />
<br />
The primary GN System is maintained in the operating mode
after lunar landing and descent engine cutoff for a period
of time that is currently unspecified. This time interval is
presently considered to be between 15 and 30 minutes in
length, during which time the primary GN system can control
an emergency take-off or abort if desired."
<br />
<br />
<br />
<br />
<span style="color: #0c343d;"><b>RESOURCES</b></span><br />
<br />
/1/<br />
<ul>
<li> (NASA CR-118610-Vol-1) PRIMARY G AND N SYSTEM LUNAR ORBIT OPERATIONS, VOLUME 1 (MIT) 258 p, R-446, edited by Norman E. Sears, April 1964</li>
<li>This report was prepared under DSR Project 55—191, sponsored by the Manned Spacecraft Center of the National Aeronautics and Space Administration through Contract NAS 9—153.</li>
<li>The following MIT Instrumentation Laboratory Apollo Space Guidance Analysis group personnel
contributed to the preparation of this report: D. S. Baker, R. D. Brown, G. W. Cherry, P. G. Felleman, R. D. Goss, E. S. Muller, R. J. Phaneuf, N.E. Sears (group leader), R. L. White, J. E. Young</li>
<li>The publication of this report does not constitute approval
by the National Aeronautics and Space Administration of the
findings or the conclusions contained therein. It is published
only for the exchange and stimulation of ideas.</li>
</ul>
<br />
/2/ Greek alphabet chart<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Oywis4Rc6lL7WaBfYOeorEq3W9tsZdcIl3Pu2wQaMN0Ic9QNJepba-ST1fI8if6pQQRU8AWSNdkFO6nlATFT8njuBC5U7dzx1DpTGvZpRkyDVJOd1ZQTJ30n3d5St8AzOS7iNyo75Zqo/s1600/Greek-Alphabet-Chart-Letters.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4Oywis4Rc6lL7WaBfYOeorEq3W9tsZdcIl3Pu2wQaMN0Ic9QNJepba-ST1fI8if6pQQRU8AWSNdkFO6nlATFT8njuBC5U7dzx1DpTGvZpRkyDVJOd1ZQTJ30n3d5St8AzOS7iNyo75Zqo/s400/Greek-Alphabet-Chart-Letters.JPG" width="393" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Greek alphabet chart</span></i></span></td></tr>
</tbody></table>
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<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-83523771503755774362016-10-31T03:18:00.000+00:002016-11-01T08:07:03.066+00:00Command Module ECS (Part 12, Apollo Control Systems)<h4>
Environmental Control System (ECS)</h4>
<br />
The Apollo environmental control system (ECS) was designed and qualified to support three crewmen for 14 days and to maintain electronic equipment within operating thermal boundaries. The system maintains the pressure atmosphere of 100 percent oxygen and removes trace contaminants and metabolic carbon dioxide by absorption in charcoal and lithium hydroxide beds. (After the Apollo 1 CM accident the launch atmosphere was changed to 60-percent oxygen and 40-percent nitrogen.)<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuZvANhGK-ZEpjlHKBeoMeyRtqxVAfrM0Vtf7IemmD8t5T-p8387s7nGMQV6AgjhaBX7UmxIGuAuWQ7x2jZfaRn4zO39AB1rj6jXXsqVgSHdhxZZvnzLau8NxUQsS_uL_S96BPX4t95LsR/s1600/46968_ca_object_representations_media_1_mediumlarge.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuZvANhGK-ZEpjlHKBeoMeyRtqxVAfrM0Vtf7IemmD8t5T-p8387s7nGMQV6AgjhaBX7UmxIGuAuWQ7x2jZfaRn4zO39AB1rj6jXXsqVgSHdhxZZvnzLau8NxUQsS_uL_S96BPX4t95LsR/s400/46968_ca_object_representations_media_1_mediumlarge.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo CM Environmental Control Unit (ECU), a major part of the ECS</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #274e13;"><i>[An Apollo Command Module (Block II) Environmental Control Unit (ECU) a major part of the Environmental Control subsystem (ECS), produced by Garrett Corp.'s AiResearch Division, Los Angeles under subcontract to North American Aviation (NAA), prime for the Apollo Command Service Module (CSM) under NASA Contact NAS 9-150. The Environmental Control Unit was the heart of the environmental control subsystem. It is a compact grouping of equipment about 29 inches long, 16 inches deep, and 33 inches at its widest point. It was mounted in the left-hand equipment bay. The unit contains the coolant control panel, water chiller, two water-glycol evaporators, carbon dioxide-odor absorber canisters, and suit heat exchanger, water separator, and compressors.]
</i></span><br />
<br />
<br />
<a name='more'></a>Temperature control is provided by heat rejection from radiators and a water evaporator. Oxygen is supplied by the cryogenic storage system, and water is supplied as a byproduct of the fuel cells. The knowledge gained from extensive ground testing and inflight experiments on the behavior of water in zero gravity led to the incorporation of a wick-type porous-plate condensate separator.
<br />
<br />
The two hardware items requiring the most extensive development were the water evaporator and the radiator. During the Apollo Program, continuous refinements have been required in the construction, material selection, and quality control of the evaporator and its control system. The wide range of the maximum and minimum heat loads led to the use of a selective stagnation radiator designed to employ the viscosity characteristics of the coolant fluid (ethylene glycol and water). The other major problems experienced were in materials selection to reduce corrosion (particularly in the coolant system), materials selection for fabrication of porous plates and heat exchangers, and material and process refinements to eliminate weld crazing.
<br />
<br />
<br />
The following schematic diagram of the Command Module ECS may be conveniently divided into the<br />
<br />
<ol>
<li> Oxygen, </li>
<li> Water,</li>
<li> Coolant,</li>
<li> Pressure-Suit, and</li>
<li> Cabin Circuits.
</li>
</ol>
<u></u><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8IYBGvcTN0AefcP2hRSWctULdId8_1f3xFllBXlu9TcW508uY415lQhOIdzsKMXnUAeK1JhJDFPf5RdWC-vrBAIUs2RuzfcEFWHqyIL5SuGlLlTUxVPD6-gcNDYM-_f5kp5M542WxJycx/s1600/Color_+Apollo_ECS_.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8IYBGvcTN0AefcP2hRSWctULdId8_1f3xFllBXlu9TcW508uY415lQhOIdzsKMXnUAeK1JhJDFPf5RdWC-vrBAIUs2RuzfcEFWHqyIL5SuGlLlTUxVPD6-gcNDYM-_f5kp5M542WxJycx/s400/Color_+Apollo_ECS_.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo Environmental Control System ECS</span></i></span></td></tr>
</tbody></table>
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<div class="separator" style="clear: both; text-align: center;">
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<div>
<u>ECS - Oxygen</u><br />
<br />
The primary oxygen source consists of two supercritical cryogenic tanks located in the Service Module (SM). These tanks also supply the oxygen reqirements of the fuel cells and are generally considered as part of the electrical power system (EPS). The two tanks contain a total of 640 pounds of oxygen, and the design specification allocates 172.6 pounds of this amount to the ECS.<br />
<br />
In comparison, the actual oxygen allocation to the ECS for the Apollo 11 mission was 72.4 pounds for planned use, 10.4 pounds for LM support, and 15.6 pounds for contingency use. The reduced consumption during the Apollo 11 mission resulted because the mission duration (196 hours) was less than that of the specification mission (336 hours or 14 days), and the cabin leakage and crew metabolic requirement values were lower than design specification requirements (see table below).
<br />
<br />
<center>
<table border="1">
<tbody>
<tr>
<th colspan="3">ECS Oxygen Consumption (Design 336 h 172.6 lbs) </th>
</tr>
<tr>
<td>Apollo 7</td>
<td>259.7 h </td>
<td>102 lbs</td>
</tr>
<tr>
<td>Apollo 8</td>
<td>146.5 h</td>
<td>51 lbs</td>
</tr>
<tr>
<td>Apollo 9</td>
<td>240.5 h</td>
<td>99 lbs</td>
</tr>
<tr>
<td>Apollo 10</td>
<td>190.0 h</td>
<td>71 lbs</td>
</tr>
<tr>
<td>Apollo 11</td>
<td>196.0 h</td>
<td>82 lbs</td>
</tr>
</tbody></table>
</center>
</div>
<br />
<i>
</i>
<br />
<br />
<br />
<u>ECS - Water</u><br />
<br />
<br />
The primary source of water for the ECS is the fuel cells, which produce approximately 0.77 lb/kWh as a byproduct of fuel-cell operation. The water storage
provisions consist of a 36-pound-capacity potable water tank, and a 56-poundcapacity waste-water tank. Excess moisture in the cabin or suit circuit gas is removed by the water separator in the suit heat exchanger and is transferred by
the cyclic accumulator to the waste-water tank for subsequent use as an expendable
coolant. The effluent from the fuel cells is directed to the potable-water tank and
is used for drinking and food reconstitution.<br />
<br />
Periodic injection of chlorine by the
crewmembers maintains bacteria control in the potable-water system. When the
potable-water tank is full, the water circuit automatically diverts the fuel-cell
output to the waste tank by elevating the water-system pressure from 25 to 30 psia.
When both tanks are full, the water-system pressure is increased to 40 psia, and the
fuel-cell effluent is dumped directly overboard. Excess water may also be dumped
manually, and this capability <u>has been used in all missions</u>. This manual operation
was chosen to preclude interference with photography, sightings with the guidance and
navigation equipment, and trajectory determination.
<br />
<br />
<br />
<br />
<u>ECS - Coolant</u><br />
<br />
<br />
The coolant system consists of a primary loop, which is operated continuously, and a secondary loop, which serves as a backup system. The primary loop uses a centrifugal pump to circulate 200 lb/hr of coolant (ethylene glycol and water) through the heat-absorption and heat-rejection equipment in the CSM. If the coolant returning from the space radiator is less than 45 degrees F, it is mixed with fluid from the CM thermal load, which has bypassed the radiator, to obtain a mixed-coolant temperature of 45 degrees F.<br />
<br />
Under mission conditions when the space radiator cannot reject the total load, no bypass occurs; instead, the glycol evaporator cools the 200-lb/hr flow to 41.5 degrees F by evaporating water at a controlled pressure of approximately 0.1 psia. The coolant flow leaving the evaporator is divided into a 35-lb/hr flow directed to the inertial measurement unit (IMU) of the guidance and navigation equipment, and a 165-lb/hr flow is routed to the suit heat exchanger through the drinking-water chiller.<br />
<br />
The suit heat exchanger provides the humidity control for the CM. The coolant leaving the suit heat exchanger enters the cabin heat exchanger and absorbs heat from the CM lighting, the electronic equipment not mounted on coldplates, the environmental loads, and the crewmembers in the shirtsleeve mode. The effluent coolant from the guidance and navigation equipment mixes with that from the cabin heat exchanger, and the 200-lb/hr flow is directed through a series-parallel arrangement of 22 coldplates, which absorb the major portion of the thermal load. The heat from the coldplate network may be diverted to the cabin heat exchanger through the cabin-temperature control valve for heating the cabin, when required. The fluid leaving the cabin-temperature control valve enters the pump, and the flow is directed to the space radiator.<br />
<br />
A secondary coolant loop is provided as a backup for the primary loop and may be operated at the discretion of the crewmembers. Both loops provide cooling for the suit and cabin atmospheres and fo,r the electronic equipment. The secondary loop does not have cabin-heating capability, nor does it provide cooling to the guidance and navigation equipment.
<br />
<br />
<br />
<br />
<u>ECS - Pressure-Suit Circuit </u><br />
<br />
<br />
The pressure-suit circuit controls the levels of carbon dioxide, odor, and humidity and can provide a habitable environment for the crewmembers if cabin pressurization is lost. When the crewmembers are in the pressure-suit mode, they are isolated from the cabin. The ventilating gas flow leaving the pressure suits passes through a debris trap which removes particles larger than 0.04 inch. Suit circuit flow is accomplished by one of two centrifugal-flow compressors which deliver 55 lb/hr of suit-circuit gas (35 cu ft/min) at a pressure rise of 10.0 inches of water with an inlet density of 0.0266 lb/cu ft.
<br />
<br />
As the ventilation gas passes through two parallel elements of lithium hydroxide and activated carbon, the carbon dioxide and odor control for the CM is accomplished.
Each element is sized for 1.5 man-days of operation at the design metabolic loads, and the elements are changed by the crew alternately every 12 hours. Twenty elements are carried for 8- to 10-day missions. The element holder, or canister, incorporates the necessary check valves, diverter valve, and interlock mechanisms which permit the changing of elements in a depressurized cabin. The canister is also designed to preclude inadvertent depressurization of the suit circuit.
<br />
<br />
The gas leaving the carbon dioxide canister enters the suit-circuit heat exchanger,
where suit-circuit heat loads are absorbed by the water and glycol. At the heat exchanger, the moisture is condensed, removed by the wicking, and transferred to the waste-water circuit by pneumatically actuated accumulators which are cycled every 10 minutes by a timing device. The normal gas exit temperature from the heat exchanger is 50" F.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX2cZtlBhCd_ewZB4GComxzIj9EHAupYj3A87xnYzUKaJewazwX0coxYLa9qzTCfVtrzKaZjtrkMgK3OsEJwjE9tbHnuhVrKjrxWC2OLNU8ItPnUhiJSD0LrKTZErUzC7Hfr4nwiJg9DAE/s1600/Apollo+11+-+16-mm+magazine+1118-B.mp4_000039416.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX2cZtlBhCd_ewZB4GComxzIj9EHAupYj3A87xnYzUKaJewazwX0coxYLa9qzTCfVtrzKaZjtrkMgK3OsEJwjE9tbHnuhVrKjrxWC2OLNU8ItPnUhiJSD0LrKTZErUzC7Hfr4nwiJg9DAE/s400/Apollo+11+-+16-mm+magazine+1118-B.mp4_000039416.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo 11 astronauts in the shirtsleeve mode 1969 inside CM</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The cool gas is distributed to the three suit-hose-connector units, which incorporate
a flow-control adjustment lever and a flow-limiting Venturi tube. When the crewmembers are in the shirtsleeve mode, their portion of the suit-circuit flow is delivered to the cabin through an orifice in the connector unit which approximates
the pressure drop of the suit. This flow is returned to the suit circuit for carbon
dioxide and humidity removal by the cabin-air-return valve located upstream of
the suit compressors.<br />
<br />
During manned ground testing and during launch, the
cabin atmosphere is a mixture of 60 percent oxygen and 40 percent nitrogen. This
is the minimum oxygen concentration which will provide a viable atmosphere
with a reduction to 5.0 psia in the cabin pressure. Subsequent to orbit insertion,
a bleed flow overboard establishes a demand on the cabin-pressure regulator and enriches the mixture to sealevel equivalent (an oxygen partial pressure
of 3.1 psia). The nitrogen content is reduced further by leakage or LM pressurizations. Technical considerations associated with the selection of the launch environment are presented in the following section.
<br />
<br />
The crewmembers undergo a period of oxygen prebreathing prior to insertion into the CM suit circuit, which has been purged to an oxygen level greater than 95 percent. This oxygen prebreathing minimizes the possibility of aeroembolism during the boost phase when cabin pressure is reduced from 14.7 to 6 psia. To prevent nitrogen leaking into the suit circuit, a positive pressure relative to the cabin pressure is maintained by a 0.5-lb/hr excess flow.
<br />
<br />
<br />
<br />
<u>ECS - Cabin Circuits</u><br />
<br />
<br />
The cabin circuit consists of two axial-flow fans. Each fan has a capacity of 86 cu ft/min at 5 psia, which circulates the CM gas through the cabin heat exchanger. A cabin-pressure relief valve relieves the cabin pressure at a differential of 6.0 psi during ascent of the spacecraft and repressurizes the cabin during descent, when the ambient pressure exceeds cabin pressure by approximately 1 psid. After splashdown, a postlanding ventilation system, consisting of an inlet valve and fan and an outlet valve, is activated by the crewmembers to ventilate the cabin until recovery.<br />
<br />
In the event of smoke, a toxic gas, or another harmful atmosphere in the cabin during the shirtsleeve environment, three oxygen masks are provided. The mask is a modified commercial full-face-type assembly with headstraps to hold it on. The oxygen is supplied at 100 psi through a flexible hose from the emergency oxygen and repressurization unit. The mask has an integral regulator that supplies oxygen on demand when the crewman inhales.
<br />
<br />
<div style="text-align: center;">
<br />
<iframe allowfullscreen="" frameborder="0" height="225" src="//www.youtube.com/embed/slUwVZJSVPY" width="400"></iframe>
</div>
<div style="text-align: center;">
<span style="color: #cc0000;"><i><span style="font-size: small;">YouTube - "Command Module Documentary"
</span></i></span></div>
<br />
<br />
<b><span style="color: #0c343d;">RESOURCES</span></b><br />
<br />
<br />
/1/ Wikipedia<br />
<br />
/2/ Apollo archives, NASA<br />
<br />
/3/ Apollo Experience Report - Command and Service Module - ECS<br />
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<div style="text-align: center;">
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Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-51123547518163273182016-10-27T23:39:00.000+01:002016-10-31T03:34:40.722+00:00CM Command Module (Part 11, Apollo Control Systems)This article handles the Apollo Command Module. The current NASA command module is called Orion capsule or crew module.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5nCvIZtVl-Xa9ik1ekgxpEBQvWcDQLFnxth0ZayJAJTAMqtjcGDBj_NQu0KYKTehKJATJdxjb_GQWRDcZd5a5qVtAyTafeIYmSCVxAnZ-_APrEOMKsePpjTwcXWZuYP368IObJhQmDyeA/s1600/APMa28.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5nCvIZtVl-Xa9ik1ekgxpEBQvWcDQLFnxth0ZayJAJTAMqtjcGDBj_NQu0KYKTehKJATJdxjb_GQWRDcZd5a5qVtAyTafeIYmSCVxAnZ-_APrEOMKsePpjTwcXWZuYP368IObJhQmDyeA/s400/APMa28.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Command Module CM with the Service Module SM connected together with an umbilical (right).</i></span> </td></tr>
</tbody></table>
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<a name='more'></a><br />
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<b><span style="color: #0c343d;">HISTORY</span></b><br />
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The Command Module CM as the Service Module SM was made by North American Aviation and the history behind them was described in <a href="http://dodlithr.blogspot.fi/2015/10/sm-service-module-part-10-apollo.html" target="_blank">the previous article</a> (see it for more details).<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXVgo7P2oa7xVmh2Jhnw3bom6lxtqg6a8VXztb3J1YPpjN71OdZFHeZzDKbEpHBFUMfpVbZbMwBfA-eZIUXuDsnKaEch-NaZLcUQN2UZZvy8JFXihpYVjbuF2pCzjjT6LltdhzkYBk9D9D/s1600/cm1.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="370" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhXVgo7P2oa7xVmh2Jhnw3bom6lxtqg6a8VXztb3J1YPpjN71OdZFHeZzDKbEpHBFUMfpVbZbMwBfA-eZIUXuDsnKaEch-NaZLcUQN2UZZvy8JFXihpYVjbuF2pCzjjT6LltdhzkYBk9D9D/s400/cm1.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Command module wooden mock up</span></i></span></td></tr>
</tbody></table>
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<b><span style="color: #0c343d;">CONSTRUCTION</span></b><br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMQJKUEEVwbk9tP-h4Vdw1Vu0OmIlzJ7YV_zEgpe7Z3EMzEb_xBZ6haGcBnz4QTOV_XAEAeEqrimaqMLo9gBwt_3izHcLJyG9HsLSfmLNCcXowEaPoNQzvj_2CCu1Gopp7FpFS7RnKRSdY/s1600/CM_Crew_Stations.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="221" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMQJKUEEVwbk9tP-h4Vdw1Vu0OmIlzJ7YV_zEgpe7Z3EMzEb_xBZ6haGcBnz4QTOV_XAEAeEqrimaqMLo9gBwt_3izHcLJyG9HsLSfmLNCcXowEaPoNQzvj_2CCu1Gopp7FpFS7RnKRSdY/s400/CM_Crew_Stations.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Command Module crew stations</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Command Module (CM) was the conical crew cabin, designed to carry three astronauts from launch to lunar orbit and back to an Earth ocean landing. It was the only component of the Apollo spacecraft to survive without major configuration changes as the program evolved from the early Apollo study designs.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdRyFJQeUwjbQ-Q6OSkuKKUaPw97scLBr49wDm2IGC6OvoNwIgk3mkISdk-wjnJ61DNKxPlxsuJXakXmG9_QufQkIwJ7NY1rR3zGIqxUnbOHT9t9MuS4j2UZ5mq_11lx5T8Px0HdsKzGpv/s1600/CM_measures.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdRyFJQeUwjbQ-Q6OSkuKKUaPw97scLBr49wDm2IGC6OvoNwIgk3mkISdk-wjnJ61DNKxPlxsuJXakXmG9_QufQkIwJ7NY1rR3zGIqxUnbOHT9t9MuS4j2UZ5mq_11lx5T8Px0HdsKzGpv/s400/CM_measures.png" width="177" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Apollo Command Module major parts and measures</i></span></td></tr>
</tbody></table>
<br />
Its exterior was covered with an ablative heat shield, and had its own reaction control system (RCS) engines to control its attitude and steer its atmospheric entry path. Parachutes were carried to slow its descent to splashdown. The module was 11.42 feet (3.48 m) tall, 12.83 feet (3.91 m) in diameter, and weighed approximately 12,250 pounds (5,560 kg).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgneiXUc9E411bjNCzxdqzD7t9_VuQqEpvB7LZn8jwf9IiVXfKZyB2BSXwHLSzNgVXqBmAaUfP5Gfrr-vG4yCb7GZJopU3flI-o5uP0pX1mCW0vOKmxUyxYEJpfAtp4LWVDkyt1blVgtZec/s1600/6a00d83451f23a69e2019b009fed73970c-800wi.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgneiXUc9E411bjNCzxdqzD7t9_VuQqEpvB7LZn8jwf9IiVXfKZyB2BSXwHLSzNgVXqBmAaUfP5Gfrr-vG4yCb7GZJopU3flI-o5uP0pX1mCW0vOKmxUyxYEJpfAtp4LWVDkyt1blVgtZec/s400/6a00d83451f23a69e2019b009fed73970c-800wi.jpg" width="291" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">R-4D RCS jet</span></i></span></td></tr>
</tbody></table>
<br />
The forward compartment contained two <a href="https://en.wikipedia.org/wiki/Reaction_control_system" target="_blank">reaction control engines</a>, the docking tunnel, and the components of the Earth Landing System (ELS). The inner pressure vessel housed the crew accommodations, equipment bays, controls and displays, and many <a href="https://en.wikipedia.org/wiki/Spacecraft" target="_blank">spacecraft</a> systems. The last section, the aft compartment, contained 10 reaction control engines and their related <a href="https://en.wikipedia.org/wiki/Propellant" target="_blank">propellant</a> tanks, fresh water tanks, and the CSM umbilical cables.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfx7K4xY5wxElot2qjjmEcbIZyeJK_SIa8tYMKYH_IhZEGkW_oKcGLZPeuwCnPdRbnBVaVnV2f_03Hg8PgxwgQy-v2EegkI6N1avsSEUvhXWTAtPjtA_v7Svb7Bewd0u3JqKBVncC-dBob/s1600/e0112d4616152af2cff357d580a516b7.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhfx7K4xY5wxElot2qjjmEcbIZyeJK_SIa8tYMKYH_IhZEGkW_oKcGLZPeuwCnPdRbnBVaVnV2f_03Hg8PgxwgQy-v2EegkI6N1avsSEUvhXWTAtPjtA_v7Svb7Bewd0u3JqKBVncC-dBob/s400/e0112d4616152af2cff357d580a516b7.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo command module main parts</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The command module's inner structure was an <a href="https://en.wikipedia.org/wiki/Aluminum" target="_blank">aluminum</a> "sandwich" consisting of a welded aluminum inner skin, a thermally bonded <a href="https://en.wikipedia.org/wiki/Composite_honeycomb" target="_blank">honeycomb</a> core, and a thin aluminum "face sheet". The central <a href="https://en.wikipedia.org/wiki/Heat_shield" target="_blank">heat shield</a> consisted of 40 individual panels interspersed with several holes and openings for the reaction control engines and after-compartment equipment access.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhj0cSsSjNqGMwWA1oA7EjFSjs-wa2of5MSI99B5avhnqlgoUjCusM-sl9cee97ckz-BkP2qKfGuZ8R4ItwSzBuFvJ9-_wavV6sn_opLbwx_Nt6Tw2RckCqCkmf_meWeVYJBisAm_YvT3IG/s1600/apollo_9_command_module_by_rlkitterman-d7o5zve.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="328" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhj0cSsSjNqGMwWA1oA7EjFSjs-wa2of5MSI99B5avhnqlgoUjCusM-sl9cee97ckz-BkP2qKfGuZ8R4ItwSzBuFvJ9-_wavV6sn_opLbwx_Nt6Tw2RckCqCkmf_meWeVYJBisAm_YvT3IG/s400/apollo_9_command_module_by_rlkitterman-d7o5zve.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Only the command module returned to the Earth after the mission</span></i></span></td></tr>
</tbody></table>
<br />
The central compartment structure consisted of an inner aluminum face sheet with a steel honeycomb core, a glass-phenolic <a href="https://en.wikipedia.org/wiki/Atmospheric_reentry#Ablative" target="_blank">ablative honeycomb heat shield</a>, a layer of q-felt fibrous <a href="https://en.wikipedia.org/wiki/Thermal_insulation" target="_blank">insulation</a>, a pore seal, a moisture barrier, and a layer of <a href="https://en.wikipedia.org/wiki/Metallized_polyethylene_terephthalate" target="_blank">aluminized PET film</a> thermal strips.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij3czpPYXpWT9NTYqiUuMHQFgBIX7gYMOcHi7GEdLHbR4Un3VdeGRh1Oo_ZT_d3pojLTZJw4r8h0QqS5PLn4yBFxt6ewFkO9s0y_JRoLajTdC0M-FmdjZM32Gr8Mb7SXX6rXiZWl6tc9Mz/s1600/CM_General_3D.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij3czpPYXpWT9NTYqiUuMHQFgBIX7gYMOcHi7GEdLHbR4Un3VdeGRh1Oo_ZT_d3pojLTZJw4r8h0QqS5PLn4yBFxt6ewFkO9s0y_JRoLajTdC0M-FmdjZM32Gr8Mb7SXX6rXiZWl6tc9Mz/s400/CM_General_3D.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>1) LEB Floodlight</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>2) X-X Foot Attenuator Strut</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>3) Hand Strap</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>4) Translation Control</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>5) Rotation Control</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>6) Internal Viewing Mirror</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>7) Y-Y Attenuator Strut</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>8) Commander's Couch (Left)</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>9) CM Pilot's Couch (Center)</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>10) LM Pilot's couch (Right)</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>11) X-X Head Attenuator Strut</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>12) Floodlight</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>13) EVA Stabilizer Strut</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>14) Z-Z Attenuator Strut</i></span></div>
<span style="font-size: small;">
</span>
<br />
<div style="color: #cc0000; text-align: center;">
<span style="font-size: small;"><i>15) L Shaped PGA Bags</i></span></div>
</td></tr>
</tbody></table>
<br />
<br />
The aft heat shield consisted of four brazed honeycomb panels, four spot-welded sheet metal fairings, and a circumferential ring. The fairing segments were attached to the honeycomb panels and ring with conventional fasteners.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi572ALZRnJ9VJZ-gsHs0Q8eaQhbM7uGq4r6jE0tyV_V7EsQoxbxKzrFARQCIxftdakobut6_76VtiBXv70O0noLaGyePU4QzzPjrHzDL8KlWM08hxg-Zsb2xg0FcKDCJmVe9aAHk0wun-z/s1600/BI230273.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="317" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi572ALZRnJ9VJZ-gsHs0Q8eaQhbM7uGq4r6jE0tyV_V7EsQoxbxKzrFARQCIxftdakobut6_76VtiBXv70O0noLaGyePU4QzzPjrHzDL8KlWM08hxg-Zsb2xg0FcKDCJmVe9aAHk0wun-z/s400/BI230273.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo Command Module Fabrication Autoclave, Downey CA</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The steel honeycomb core and outer face sheets were then thermally bonded to the inner skin in a giant <a href="https://en.wikipedia.org/wiki/Autoclave" target="_blank">autoclave</a>. The aft heat shield was nearly identical to the central, except no alluminized film layer was applied.<br />
<br />
<br />
<b><span style="color: #0c343d;">Earth Landing Ssystem (ELS)</span></b><br />
<br />
The components of the ELS were housed around the forward docking tunnel. The forward compartment was separated from the central by a bulkhead and was divided into four 90-degree wedges. The ELS consisted of three main <a href="https://en.wikipedia.org/wiki/Parachute" target="_blank">parachutes</a>, three pilot parachutes, two drogue parachute motors, three upright bags, a sea recovery cable, a dye marker, and a swimmer umbilical. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEge2zjr14lxSTfBduW0ZbqxPQEKkKua2XlbAuFdyM5P7FFaLkPAoLYpyAZpCZFzUtFaxR6l3GjibhpypMna5gMmqeVAOh0oRd0NmTffgv7ZCffCb-A3pwtjaI3Umt-rVja-WkfBm-30X5hb/s1600/CM+recuperation+01.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEge2zjr14lxSTfBduW0ZbqxPQEKkKua2XlbAuFdyM5P7FFaLkPAoLYpyAZpCZFzUtFaxR6l3GjibhpypMna5gMmqeVAOh0oRd0NmTffgv7ZCffCb-A3pwtjaI3Umt-rVja-WkfBm-30X5hb/s400/CM+recuperation+01.jpg" width="330" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">CM after landing</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Command Module's center of mass was offset a foot or so from the center of pressure (along the symmetry axis). This provided a rotational <a href="https://en.wikipedia.org/wiki/Torque" target="_blank">moment</a> during reentry, angling the capsule and providing some lift (a <a href="https://en.wikipedia.org/wiki/Lift_to_drag_ratio" target="_blank">lift to drag ratio</a> of about 0.368). The capsule was then steered by rotating the capsule using thrusters; when no steering was required, the capsule was spun slowly, and the lift effects cancelled out.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLAqOt6z4S2ubu_PNhTK7s6ubN5SoP8_JPz4Z5oy0_G45FlIooD-f9QC5XHuadx7ctsUdQfX4EF1dsBV8p2jiTsk07WlNliDNLxGAEV3UBDxawKF5nmUNfFkxG7z6oIxFKwSYkCyND0MXT/s1600/Command_Module_Aerodynamics.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjLAqOt6z4S2ubu_PNhTK7s6ubN5SoP8_JPz4Z5oy0_G45FlIooD-f9QC5XHuadx7ctsUdQfX4EF1dsBV8p2jiTsk07WlNliDNLxGAEV3UBDxawKF5nmUNfFkxG7z6oIxFKwSYkCyND0MXT/s400/Command_Module_Aerodynamics.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo CM aerodynamics during re-entry</span></i></span></td></tr>
</tbody></table>
<br />
<br />
This system greatly reduced the <a href="https://en.wikipedia.org/wiki/G-force" target="_blank">g-force</a> experienced by the astronauts, permitted a reasonable amount of directional control and allowed the capsule's splashdown point to be targeted within a few miles.<br />
<br />
YouTube video: "<a href="https://youtu.be/QglyJDvZkew" target="_blank">Apollo Command Module Block II Parachute Installation and Testing</a>" <br />
<br />
At 24,000 feet (7.3 km) the forward heat shield was jettisoned using four pressurized-gas compression springs. The drogue parachutes were then deployed, slowing the spacecraft to 125 miles per hour (201 km/h). At 10,700 feet (3.3 km) the drogues were jettisoned and the pilot parachutes, which pulled out the mains, were deployed. These slowed the CM to 22 miles per hour (35 km/h) for splashdown.<br />
<br />
YouTube video: "<a href="https://youtu.be/E-Vd75Ptg9I" target="_blank">Apollo 15 Splashdown</a>"<br />
<br />
The portion of the capsule which first contacted the water surface was built with crushable ribs to further mitigate the force of impact. The Apollo Command Module could safely parachute to an ocean landing with at least two parachutes (as occurred on <a href="https://en.wikipedia.org/wiki/Apollo_15" target="_blank">Apollo 15</a>), the third parachute being a safety precaution.<br />
<br />
YouTube video: "<a href="https://youtu.be/nyFYolprgBA" target="_blank">Apollo Block II Parachute Fabrication Rigging Packing</a>" <br />
<br />
<br />
<b><span style="color: #0c343d;">Reaction Control System (RCS)</span></b><br />
<div>
<br />
The Command Module <a href="https://en.wikipedia.org/wiki/Reaction_control_system" rel="nofollow" target="_blank">attitude control system</a> consisted of twelve 93-pound-force (410 N) attitude control jets; ten were located in the aft compartment, and two pitch motors in the forward compartment. Four tanks stored 270 pounds (120 kg) of <a href="https://en.wikipedia.org/wiki/Monomethylhydrazine" target="_blank">mono-methyl hydrazine</a> fuel and <a href="https://en.wikipedia.org/wiki/N2O4" target="_blank">nitrogen tetroxide</a> oxidizer. They were pressurized by 1.1 pounds (0.50 kg) of <a href="https://en.wikipedia.org/wiki/Helium" target="_blank">helium</a> stored at 4,150 pounds per square inch (28.6 MPa) in two tanks.</div>
<div>
<br /></div>
<div>
<br />
<b><span style="color: #0c343d;">Hatches </span></b><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS7fgzSkL1JhFn1BBQ_ngvszNle1kRzsen1T41SK9NOtFT11Da6qtRLCj8JWPybtnBEMIWJ3FwJwvB7hUK8LYpSapLnWMjuvQQokq-LDfQP4Pju8MGyjKFk5q_RLtyHeJqp80IvL8nPhoY/s1600/Commandmoduleinterior.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgS7fgzSkL1JhFn1BBQ_ngvszNle1kRzsen1T41SK9NOtFT11Da6qtRLCj8JWPybtnBEMIWJ3FwJwvB7hUK8LYpSapLnWMjuvQQokq-LDfQP4Pju8MGyjKFk5q_RLtyHeJqp80IvL8nPhoY/s400/Commandmoduleinterior.JPG" width="287" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Command Module interior</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The forward docking hatch was mounted at the top of the docking tunnel. It was 30 inches (76 cm) in diameter and weighed 80 pounds (36 kg). It was constructed from two machined rings that were weld-joined to a brazed honeycomb panel.<br />
<br />
The exterior side was covered with a 0.5-inch (13 mm) of insulation and a layer of aluminum foil. It was latched in six places and operated by a pump handle. The hatch contained a valve in its center, used to equalize the pressure between the tunnel and the CM so the hatch could be removed. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZT8slqN8XgXbr1WMVGVkmd0AhR3LhkcrSvsN9UPVtHZ5G2qRJoVS0S8Sq-tIcCAQT8_getu05gCiq-2g_My39ibJvoowuk9qlfY9sputBHVkR7wFQHJ10y2HwG1hGHCm6v8LaHsoitPO7/s1600/CM+block2+hatch.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZT8slqN8XgXbr1WMVGVkmd0AhR3LhkcrSvsN9UPVtHZ5G2qRJoVS0S8Sq-tIcCAQT8_getu05gCiq-2g_My39ibJvoowuk9qlfY9sputBHVkR7wFQHJ10y2HwG1hGHCm6v8LaHsoitPO7/s400/CM+block2+hatch.jpg" width="305" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Unified Crew Hatch (UCH) </span></i></span><span style="color: #cc0000;"><i><span style="font-size: small;">It is referred to as a "unified" hatch because it incorporates both
the outer heat shield hatch and inner crew compartment pressure hatch in a
single hatch. This hatch was <a href="http://heroicrelics.org/info/apollo-6/apollo-6-hatch.html" target="_blank">initially flown</a> on <a href="http://heroicrelics.org/fernbank/apollo-6/index.html" target="_blank">Apollo 6</a>.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Unified Crew Hatch (UCH) measured 29 inches (74 cm) high, 34 inches (86 cm) wide, and weighed 225 pounds (102 kg). It was operated by a pump handle, which drove a <a href="https://en.wikipedia.org/wiki/Ratchet_%28device%29" target="_blank">ratchet</a> mechanism to open or close fifteen latches simultaneously. </div>
<div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhU26-EZGzRwLJqq3F415iLPbJk3Dp4XKlzqMBfXah2mT75i0Eu9-3tMWoovWPzZklltwvu2_SMYu1vKpEG4ye44UDAW-LVMwX5t07Y-lkB4TvFYrCmAxXMJ3qI2VlIr5ZAtthCdHWvkZeA/s1600/cm-hatch.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="327" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhU26-EZGzRwLJqq3F415iLPbJk3Dp4XKlzqMBfXah2mT75i0Eu9-3tMWoovWPzZklltwvu2_SMYu1vKpEG4ye44UDAW-LVMwX5t07Y-lkB4TvFYrCmAxXMJ3qI2VlIr5ZAtthCdHWvkZeA/s400/cm-hatch.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">UCH crew hatch in detail</span></i></span></td></tr>
</tbody></table>
<br />
<br /></div>
<div>
<br />
<b><span style="color: #0c343d;">Docking assembly </span></b><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5O6UGgZob7l5t0p_xRdj-pkgfwwU6aOsqZm9SBZDL4IDiQp6mKhdmiH8yntBviyB1bVSrDnCWbKFrc_esjb2ZRA0qJahZ9gGLU0VhahWw3qF5L17AGiNQub6q1yJeAIfGSL-urX3JpvQM/s1600/c137.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="346" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5O6UGgZob7l5t0p_xRdj-pkgfwwU6aOsqZm9SBZDL4IDiQp6mKhdmiH8yntBviyB1bVSrDnCWbKFrc_esjb2ZRA0qJahZ9gGLU0VhahWw3qF5L17AGiNQub6q1yJeAIfGSL-urX3JpvQM/s400/c137.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">North
American engineers favored probe and drogue devices to dock the
command module with the lunar module. The CM probe would slip into
the LM's dish-shaped drogue, and 12 latches on the docking ring would
engage, to lock the spacecraft together, airtight. The astronauts
could now remove a hatch, take out the docking devices, and travel
between the two spacecraft. When operations were finished, they would
return to the CM, reinsert the devices, install the hatch, and
release the latches to disengage from the LM.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Apollo spacecraft docking mechanism was a <a href="https://en.wikipedia.org/wiki/Spacecraft_Docking_and_Berthing_Mechanisms#Androgyny" target="_blank">non-androgynous</a> system, consisting of a probe located in the nose of the CSM, which connected to the drogue, a truncated cone located on the Lunar Module.<br />
<br />
The probe was extended like a <a href="https://en.wikipedia.org/wiki/Jack_%28device%29" target="_blank">scissor jack</a> to capture the drogue on initial contact, known as <a href="https://en.wikipedia.org/wiki/Docking_and_berthing_of_spacecraft" target="_blank">soft docking</a>. Then the probe was retracted to pull the vehicles together and establish a firm connection, known as "hard docking". The mechanism was specified by NASA to have the following functions:</div>
<div>
<br /></div>
<div>
<ul>
<li>Allow the two vehicles to connect, and attenuate excess movement and energy caused by docking </li>
<li>Align and center the two vehicles and pull them together for capture </li>
<li>Provide a rigid structural connection between both vehicles, and be capable of removal and re-installation by a single crewman </li>
<li>Provide a means of remote separation of both vehicles for the return to Earth, using <a href="https://en.wikipedia.org/wiki/Pyrotechnic_fastener" target="_blank">pyrotechnic fasteners</a> at the circumference of the CSM docking collar </li>
<li>Provide redundant power and logic circuits for all electrical and pyrotechnic components. </li>
</ul>
<div>
<br /></div>
<div>
<br /></div>
<b><span style="color: #0c343d;">Coupling </span></b><br />
<br />
The probe head located in the CSM was self-centering and gimbal-mounted to the probe piston. As the probe head engaged in the opening of the drogue socket, three spring-loaded latches depressed and engaged. These latches allowed a so-called 'soft dock' state and enabled the pitch and yaw movements in the two vehicles to subside.<br />
<br />
Excess movement in the vehicles during the 'hard dock' process could cause damage to the docking ring and put stress on the upper tunnel. A depressed locking trigger link at each latch allowed a spring-loaded spool to move forward, maintaining the toggle linkage in an over-center locked position. In the upper end of the Lunar Module tunnel, the drogue, which was constructed of 1-inch-thick aluminum honeycomb core, bonded front and back to aluminum face sheets, was the receiving end of the probe head capture latches. </div>
<div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiW52AlcAohOSG7AsBrvbXVw6o0J61evDMFfATnzRLJzOVwMmyE91psNbxKDc9swp6g2LjOBD1BPyrp-Kwl-KTdBxzZ0awI2PMPilOB_-VZZXWxTtXK43WahFkpR_7L0d_P3UO2kUybKZ2O/s1600/csm-lm2b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiW52AlcAohOSG7AsBrvbXVw6o0J61evDMFfATnzRLJzOVwMmyE91psNbxKDc9swp6g2LjOBD1BPyrp-Kwl-KTdBxzZ0awI2PMPilOB_-VZZXWxTtXK43WahFkpR_7L0d_P3UO2kUybKZ2O/s400/csm-lm2b.jpg" width="347" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo CSM (Command Service Module) docked with the LM (Lunar Module)</span></i></span></td></tr>
</tbody></table>
</div>
<div>
<br />
<b><span style="color: #0c343d;">Retraction </span></b><br />
<br />
After the initial capture and stabilization of the vehicles, the probe was capable of exerting a closing force of 1,000 pounds-force (4.4 kN) to draw the vehicles together. This force was generated by gas pressure acting on the center piston within the probe cylinder.<br />
<br />
Piston retraction compressed the probe and interface seals and actuated the 12 automatic ring latches which were located radially around the inner surface of the CSM docking ring. The latches were manually re-cocked in the docking tunnel by an astronaut after each hard docking event (lunar missions required two dockings). </div>
<div>
<br /></div>
<div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG7Zicy5RzXeDeTDBBhiKgBmONFnakOVbHHfb7a54vls1CKc9qDuoo_1GH7YSSD4Mh-baVWRLZAFaNgEp_6kIUCxa-ch9igALTygBJXvi-VNnfUE9vrLq4RPX-eExrgWUSMq3fM_t8o6OE/s1600/csm-lm1b.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="245" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgG7Zicy5RzXeDeTDBBhiKgBmONFnakOVbHHfb7a54vls1CKc9qDuoo_1GH7YSSD4Mh-baVWRLZAFaNgEp_6kIUCxa-ch9igALTygBJXvi-VNnfUE9vrLq4RPX-eExrgWUSMq3fM_t8o6OE/s400/csm-lm1b.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo CSM and LM docked</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<b><span style="color: #0c343d;">Separation </span></b><br />
<br />
An automatic extension latch attached to the probe cylinder body engaged and retained the probe center piston in the retracted position. Before vehicle separation in lunar orbit, manual cocking of the twelve ring latches was accomplished. The separating force from the internal pressure in the tunnel area was then transmitted from the ring latches to the probe and drogue. In undocking, the release of the capture latches was accomplished by electrically energizing tandem-mounted DC rotary solenoids located in the center piston.<br />
<br />
In a temperature degraded condition, a single motor release operation was done manually in the Lunar Module by depressing the locking spool through an open hole in the probe heads, while release from the CSM was done by rotating a release handle at the back of the probe to rotate the motor torque shaft manually.<br />
<br />
When the Command and Lunar Modules separated for the last time just before re-entry, the probe and forward docking ring were pyrotechnically separated, leaving all docking equipment attached to the lunar module. In the event of an abort during launch from Earth, the same system would have explosively jettisoned the docking ring and probe from the CM as it separated from the boost protective cover.<br />
<br />
<br />
<b><span style="color: #0c343d;">Cabin interior arrangement</span></b><br />
<br />
For a general view of the CM internals look this video.<br />
<br />
YouTube video: <a href="https://youtu.be/-fs8gkiap6U" target="_blank">"James Burke takes us Inside the Apollo Command Module"</a><br />
<br />
Here is a more detailed cutaway of the CM interior.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHxLPAKZk0YHqnMdPxfS6SBlEgypcTB4K1JThcQ2wNDG34WCLa3bbEcramboFO8rFqZx2lDfZ_dtktTepG_pQtXn9y9hFaak7Uvlcyg9QAoLVd4QgQibDlSSQ6rPmMF4gJKbFdhOwudcze/s1600/Commandmoduleinterior.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhHxLPAKZk0YHqnMdPxfS6SBlEgypcTB4K1JThcQ2wNDG34WCLa3bbEcramboFO8rFqZx2lDfZ_dtktTepG_pQtXn9y9hFaak7Uvlcyg9QAoLVd4QgQibDlSSQ6rPmMF4gJKbFdhOwudcze/s400/Commandmoduleinterior.JPG" width="287" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 12.8px;"><span style="color: #cc0000; font-size: small;"><i>Apollo Command Module (CM) interior</i></span></td></tr>
</tbody></table>
<br />
The central pressure vessel of the command module was its sole habitable compartment. It had an interior volume of 210 cubic feet (5.9 m3) and housed the main control panels, crew seats, guidance and navigation systems, food and equipment lockers, the waste management system, and the docking tunnel. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuAny4VJDWmZY1FGBOEMtEPc9sDNUbQPf_1XyeJnES3eITs5JZyLnHXNO8KrWL_gWGmIdaml6skoYIF54sRikl16CySlqPb2ikXi9CLy5CYgiSE7mmZIh2Njov5stavYsqGWExULqV8Kug/s1600/Apollo_Command_Module_Main_Control_Panel.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="191" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuAny4VJDWmZY1FGBOEMtEPc9sDNUbQPf_1XyeJnES3eITs5JZyLnHXNO8KrWL_gWGmIdaml6skoYIF54sRikl16CySlqPb2ikXi9CLy5CYgiSE7mmZIh2Njov5stavYsqGWExULqV8Kug/s400/Apollo_Command_Module_Main_Control_Panel.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">CM main control panel</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Dominating the forward section of the cabin was the crescent-shaped main display panel measuring nearly seven feet (2.1 m) wide and three feet (0.9 m) tall. It was arranged into three panels, each emphasizing the duties of each crew member. The mission commander’s panel (left side) included the <a href="https://en.wikipedia.org/wiki/Velocity" target="_blank">velocity</a>, attitude, and <a href="https://en.wikipedia.org/wiki/Altitude" target="_blank">altitude</a> indicators, the primary flight controls, and the main FDAI (Flight Director Attitude Indicator). <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqVuJx_tsr892s1KC9DYcZMOqUBOetWMEFfGCIbSqTUD7BgCN1LRz8kV2P1GJ01YC9OI1nvttgPMlhPiSemvkOIaf9DygpHKXpY7LNnuK7HYDhltK2neLK_ZvyhBrn3CkjIWMGhSPTtwZ0/s1600/SC_front.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqVuJx_tsr892s1KC9DYcZMOqUBOetWMEFfGCIbSqTUD7BgCN1LRz8kV2P1GJ01YC9OI1nvttgPMlhPiSemvkOIaf9DygpHKXpY7LNnuK7HYDhltK2neLK_ZvyhBrn3CkjIWMGhSPTtwZ0/s400/SC_front.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">CM seats</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The CM pilot served as navigator, so his control panel (center) included the <a href="https://en.wikipedia.org/wiki/Apollo_Guidance_Computer" target="_blank">Guidance and Navigation computer</a> controls, the caution and warning indicator panel, the event timer, the Service Propulsion System and RCS controls, and the environmental control system controls. <br />
<br />
The LM pilot served as systems engineer, so his control panel (right-hand side) included the <a href="https://en.wikipedia.org/wiki/Fuel_cell" target="_blank">fuel cell</a> gauges and controls, the electrical and <a href="https://en.wikipedia.org/wiki/Battery_%28electricity%29" target="_blank">battery</a> controls, and the communications controls. <br />
<br />
Flanking the sides of the main panel were sets of smaller control panels. On the left side were a <a href="https://en.wikipedia.org/wiki/Circuit_breaker" target="_blank">circuit breaker</a> panel, audio controls, and the SCS power controls. On the right were additional circuit breakers and a redundant audio control panel, along with the environmental control switches. In total, the command module panels included 24 instruments, 566 switches, 40 event indicators, and 71 lights. <br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTLgXhie5caHa4VHqT9FL-xYjOOQutxdg3igxygig8Wj1cnKPdArGDJMioRzCl-ZmFAzZzw_GlZZpGNjyIiXLnAye_bkBQkuDID7O_wpujgnEihDcDwi5VSX-rpIyhW1N9wriXaUHgVIo_/s1600/Weber.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTLgXhie5caHa4VHqT9FL-xYjOOQutxdg3igxygig8Wj1cnKPdArGDJMioRzCl-ZmFAzZzw_GlZZpGNjyIiXLnAye_bkBQkuDID7O_wpujgnEihDcDwi5VSX-rpIyhW1N9wriXaUHgVIo_/s400/Weber.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">CM crew couches</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The three crew couches were constructed from hollow <a href="https://en.wikipedia.org/wiki/Steel" target="_blank">steel</a> tubing and covered in a heavy, fireproof cloth known as Armalon. The leg pans of the two outer couches could be folded in a variety of positions, while the hip pan of the center couch could be disconnected and laid on the aft bulkhead. One <a href="https://en.wikipedia.org/wiki/Rotation" target="_blank">rotation</a> and one <a href="https://en.wikipedia.org/wiki/Translation_%28physics%29" target="_blank">translation</a> hand controller was installed on the armrests of the left-hand couch. The translation controller was used by the crew member performing the LM docking maneuver, usually the CM Pilot. The center and right-hand couches had duplicate rotational controllers. The couches were supported by eight shock-attenuating struts, designed to ease the impact of touchdown on water or, in case of an emergency landing, on solid ground.</div>
<div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5r8jiFQrYdnDkCwwzi-qHVgL8Wv3FP6zFDQGz_6qk6KT7duVROZarYrNlrHdE2dFUz2YONR7vY101CpmZfhH9EkbYf0DftcHySR0G05osKW_Q89MvSujlY5jG21ZhzWzpADDIhGh8KzTt/s1600/cm_stowage.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="303" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5r8jiFQrYdnDkCwwzi-qHVgL8Wv3FP6zFDQGz_6qk6KT7duVROZarYrNlrHdE2dFUz2YONR7vY101CpmZfhH9EkbYf0DftcHySR0G05osKW_Q89MvSujlY5jG21ZhzWzpADDIhGh8KzTt/s400/cm_stowage.gif" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo 16 CM stowage locations</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The contiguous cabin space was organized into six equipment bays:<br />
<ul>
<li>The lower equipment bay, which housed the <a href="https://en.wikipedia.org/wiki/Apollo_Guidance_Computer" target="_blank">Guidance and Navigation computer</a>, <a href="https://en.wikipedia.org/wiki/Sextant" target="_blank">sextant</a>, <a href="https://en.wikipedia.org/wiki/Telescope" target="_blank">telescope</a>, and <a href="https://en.wikipedia.org/wiki/Inertial_Measurement_Unit" target="_blank">Inertial Measurement Unit</a>; various communications beacons; medical stores; an audio center; the <a href="https://en.wikipedia.org/wiki/S-band" target="_blank">S-band</a> power amplifier; etc. There was also an extra rotation hand controller mounted on the bay wall, so the CM Pilot/navigator could rotate the spacecraft as needed while standing and looking through the telescope to find stars to take navigational measurements with the sextant. This bay provided a significant amount of room for the astronauts to move around in, unlike the cramped conditions which existed in the previous <a href="https://en.wikipedia.org/wiki/Project_Mercury" target="_blank">Mercury</a> and <a href="https://en.wikipedia.org/wiki/Project_Gemini" target="_blank">Gemini</a> spacecraft. </li>
<li>The left-hand forward equipment bay, which contained four food storage compartments, the cabin <a href="https://en.wikipedia.org/wiki/Heat_exchanger" target="_blank">heat exchanger</a>, <a href="https://en.wikipedia.org/wiki/Pressure_suit" target="_blank">pressure suit</a> connector, potable <a href="https://en.wikipedia.org/wiki/Water" target="_blank">water</a> supply, and G&N telescope <a href="https://en.wikipedia.org/wiki/Eyepiece" target="_blank">eyepieces</a>. </li>
<li>The right-hand forward equipment bay, which housed two <a href="https://en.wikipedia.org/wiki/Survival_kit" target="_blank">survival kit</a> containers, a data card kit, flight data books and files, and other mission documentation. </li>
<li>The left hand intermediate equipment bay, housing the <a href="https://en.wikipedia.org/wiki/Oxygen" target="_blank">oxygen</a> surge tank, water delivery system, food supplies, the cabin pressure relief valve controls, and the ECS package. </li>
<li>The right hand intermediate equipment bay, which contained the bio instrument kits, waste management system, food and sanitary supplies, and a waste storage compartment. </li>
<li>The aft storage bay, behind the crew couches. This housed the 70 mm <a href="https://en.wikipedia.org/wiki/Camera" target="_blank">camera</a> equipment, the astronaut’s garments, tool sets, storage bags, a <a href="https://en.wikipedia.org/wiki/Fire_extinguisher" target="_blank">fire extinguisher</a>, <a href="https://en.wikipedia.org/wiki/Carbon_dioxide" target="_blank">CO2</a> absorbers, sleep restraint ropes, <a href="https://en.wikipedia.org/wiki/Spacesuit" target="_blank">spacesuit</a> maintenance kits, 16mm camera equipment, and the contingency lunar sample container. </li>
</ul>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSoytOHRL-l3bu5lHOzYA6AsJVH8gzlz49NAMnZIedaSwd9FiW3sdrriceiqpXJzMTVMrI0202MvD4P6QGhwHNTlG8U1BBhCng6qPu0FOiwUlRagi8WRLfn3Rsx6Uyxt28HQmIqPCGr-c5/s1600/windows.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="352" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhSoytOHRL-l3bu5lHOzYA6AsJVH8gzlz49NAMnZIedaSwd9FiW3sdrriceiqpXJzMTVMrI0202MvD4P6QGhwHNTlG8U1BBhCng6qPu0FOiwUlRagi8WRLfn3Rsx6Uyxt28HQmIqPCGr-c5/s400/windows.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo CM windows:</span></i></span><br />
<span style="color: #cc0000;"><i><span style="font-size: small;">1 and 5 - side windows,</span></i></span><br />
<span style="color: #cc0000;"><i><span style="font-size: small;">2 and 4 - forward </span></i></span><span style="color: #cc0000;"><i><span style="font-size: small;">rendezvous windows,</span></i></span><br />
<span style="color: #cc0000;"><i><span style="font-size: small;">3 - hatch window </span></i></span></td></tr>
</tbody></table>
<br />
<br />
The CM had five windows.<br />
<ul>
<li> 1 and 5 - The two side windows measured 13 inches (330 mm) square next to the left and right-hand couches.</li>
<li> 2 and 4 - Two forward-facing triangular rendezvous windows measured 8 by 13 inches (204 by 330 mm), used to aid in <a href="https://en.wikipedia.org/wiki/Space_rendezvous" target="_blank">rendezvous</a> and docking with the LM.</li>
<li> 3 - The circular hatch window was 10 5/8 in. diameter (27 cm) and was directly over the center couch.</li>
</ul>
<br />
Each window assembly consisted of three thick panes of glass. The inner two panes, which were made of <a href="https://en.wikipedia.org/wiki/Aluminosilicate" target="_blank">aluminosilicate</a>, made up part of the module's pressure vessel. The fused silica outer pane served as both a debris shield and as part of the heat shield. Each pane had an anti-reflective coating and a blue-red reflective coating on the inner surface.<br />
<br />
<br />
<b><br /></b>
<b>Major differences between Block I and Block II
</b><br />
<br />
<ul>
<li>The Block II used a one-piece, quick-release, outward opening hatch instead of the two-piece plug hatch used on Block I, in which the inner piece had to be unbolted and placed inside the cabin in order to enter or exit the spacecraft (a flaw that doomed the Apollo 1 crew). The Block II hatch could be opened quickly in case of an emergency. (Both hatch versions were covered with an extra, removable section of the Boost Protective Cover which surrounded the CM to protect it in case of a launch abort.) </li>
<li> The Block I forward access tunnel was smaller than Block II, and intended only for emergency crew egress after splashdown in case of problems with the main hatch. It was covered with a removable plug in the nose of the forward heat shield. Block II contained a shorter forward heat shield with a flat removable hatch, beneath a docking ring and probe mechanism which captured and held the LM. </li>
<li> The aluminized PET film layer, which gave the Block II heat shield a shiny mirrored appearance, was absent on Block I, exposing the light gray fiberglass material, which on some flights was painted white. </li>
<li> The Block I VHF scimitar antennas were located in two semicircular strakes originally thought necessary to help stabilize the CM during reentry. However, the unmanned reentry tests proved these to be unnecessary for stability, and also aerodynamically ineffective at high simulated lunar reentry speeds. Therefore, the strakes were removed from Block II and the antennas were moved to the Service Module. </li>
<li> The Block I CM/SM umbillical connector was smaller than on Block II, located near the crew hatch instead of nearly 180 degrees away from it. The separation point was between the modules, instead of the larger hinged arm mounted on the Service Module, separating at the CM sidewall on Block II. </li>
<li> The two negative pitch RCS engines located in the forward compartment were arranged vertically on Block I, and horizontally on Block II.
</li>
</ul>
<br />
<br />
<br />
<b><span style="color: #0c343d;">Specifications</span></b><br />
<br />
Measures:</div>
<div>
<ul>
<li>Length: 11.4 ft (3.5 m) </li>
<li>Diameter: 12.8 ft (3.9 m) </li>
</ul>
<div>
<br /></div>
Crew:</div>
<div>
<ul>
<li>3 astronauts</li>
</ul>
</div>
<div>
<br />
Crew cabin volume:</div>
<div>
<ul>
<li>218 cu ft (6.2 m3) living space,</li>
<li>pressurized 366 cu ft (10.4 m3) </li>
</ul>
</div>
<div>
<br /></div>
<div>
Mass: 12,250 lb (5,560 kg)</div>
<div>
<ul>
<li>Structure mass: 3,450 lb (1,560 kg) </li>
<li>Heat shield mass: 1,870 lb (850 kg) </li>
<li>RCS engine mass: twelve x 73.3 lb (33.2 kg) </li>
<li>RCS propellant mass: 270 lb (120 kg) </li>
<li>Recovery equipment mass: 540 lb (240 kg) </li>
<li><a href="https://en.wikipedia.org/wiki/Navigation" target="_blank">Navigation</a> equipment mass: 1,110 lb (500 kg) </li>
<li><a href="https://en.wikipedia.org/wiki/Telemetry" target="_blank">Telemetry</a> equipment mass: 440 lb (200 kg) </li>
<li>Electrical equipment mass: 1,500 lb (680 kg) </li>
<li>Communications systems mass: 220 lb (100 kg) </li>
<li>Crew couches and provisions mass: 1,200 lb (540 kg) </li>
<li>Environmental Control System mass: 440 lb (200 kg) </li>
<li>Misc. contingency mass: 440 lb (200 kg) </li>
</ul>
</div>
<div>
<br />
RCS:</div>
<div>
<ul>
<li>twelve 93 lbf (410 N) thrusters, firing in pairs </li>
<li>RCS propellants: UDMH/N2O4 </li>
</ul>
<div>
<br /></div>
</div>
<div>
Water</div>
<div>
<ul>
<li>Drinking water capacity: 33 lb (15 kg) </li>
<li>Waste water capacity: 58 lb (26 kg) </li>
</ul>
<div>
<br /></div>
<div>
Life support</div>
<ul>
<li>CO2 scrubber: <a href="https://en.wikipedia.org/wiki/Lithium_hydroxide" target="_blank">lithium hydroxide</a> </li>
<li>Odor absorber: <a href="https://en.wikipedia.org/wiki/Activated_carbon" target="_blank">activated charcoal</a> </li>
</ul>
</div>
<div>
<br />
Electric system batteries:</div>
<div>
<ul>
<li>three 40 ampere-hour <a href="https://en.wikipedia.org/wiki/Silver-oxide_battery" target="_blank">silver-zinc batteries</a>;</li>
<li>two 0.75 ampere-hour silver-zinc pyrotechnic batteries </li>
</ul>
</div>
<div>
<br />
Parachutes:</div>
<div>
<ul>
<li>two 16 feet (4.9 m) conical ribbon drogue parachutes;</li>
<li>three 7.2 feet (2.2 m) ringshot pilot parachutes;</li>
<li>three 83.5 feet (25.5 m) ringsail main parachutes</li>
</ul>
</div>
<div>
<br />
<br />
<b><span style="color: #0c343d;">RCS Jets</span></b><br />
<br />
<br />
<a href="https://en.wikipedia.org/wiki/Marquardt_Corporation" target="_blank">Marquardt Company</a>'s employee Gerald R. Pfeifer remembers:
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKuAqmrApIP-DRQBQQOW20JSgxuWDdBmAEBHLtLgNCGogFfRViJy5BI6DoxYqhXEtnhccqrSj7uJ0600786bcjPqbhPIWzHjNQoEeI54LLrfx88moDliM_chpcAFQMTylHSeTejjYGGVkr/s1600/Gerald+R.+Jerry+Pfeifer%252C+Marquardt+Company.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKuAqmrApIP-DRQBQQOW20JSgxuWDdBmAEBHLtLgNCGogFfRViJy5BI6DoxYqhXEtnhccqrSj7uJ0600786bcjPqbhPIWzHjNQoEeI54LLrfx88moDliM_chpcAFQMTylHSeTejjYGGVkr/s400/Gerald+R.+Jerry+Pfeifer%252C+Marquardt+Company.png" width="280" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Gerald R. "Jerry" Pfeifer</span></i></span></td></tr>
</tbody></table>
<i>"We made about 650 <a href="https://en.wikipedia.org/wiki/R-4D" target="_blank">R-4D engines</a>. That was 650 production units. We actually flew 469 of them during the Apollo Program, which is an astounding number of little rocket engines that actually fly in space all on one program. In all that time, and the millions of cycles that were put on during that whole program, there was not one R-4D valve or engine failure. We were really kind of tickled that we may have done something good." </i></div>
<div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSMEoPks_8SZmKe9wXE8MYK9eyHLB8yLJa-vP1aAIXgfZEO7WmweBlOoZOeBsrroWVDSNF17X2qG_80kxVGJbRkc2s6gi1sXQnTJCsJ8xGufKXR3ywX5lkRkfclBQbZnWGy6wpyNRz0e7o/s1600/RCS_R-4D_thruster_400.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSMEoPks_8SZmKe9wXE8MYK9eyHLB8yLJa-vP1aAIXgfZEO7WmweBlOoZOeBsrroWVDSNF17X2qG_80kxVGJbRkc2s6gi1sXQnTJCsJ8xGufKXR3ywX5lkRkfclBQbZnWGy6wpyNRz0e7o/s400/RCS_R-4D_thruster_400.jpg" width="185" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">R-4D RCS jet (something good)</span></i></span></td></tr>
</tbody></table>
<br /></div>
<br />
<div style="text-align: center;">
<br />
<iframe allowfullscreen="" frameborder="0" height="225" src="//www.youtube.com/embed/slUwVZJSVPY" width="400"></iframe>
</div>
<div style="text-align: center;">
<span style="color: #cc0000;"><i><span style="font-size: small;">YouTube - "Command Module Documentary"
</span></i></span></div>
<br />
<br />
<b><span style="color: #0c343d;">RESOURCES</span></b><br />
<br />
<br />
/1/ Wikipedia<br />
<br />
/2/ Apollo archives, NASA<br />
<br />
/3/ Apollo Experience Report - Command and Service Module - ECS<br />
<br />
<div style="text-align: center;">
<br />
* * *
</div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-10207018595109613362016-10-18T13:55:00.003+01:002016-10-18T14:06:27.409+01:00JB-10 Latest JetpackLooks like Jetpack people have again created a new version of their "real jetpack", real meaning that it really uses jets and not rockets like some earlier versions of jetpacks did.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9iFBb7v6yB9eAGU0z4BOxfUJWDR2S4z17lSOYVii94ZB8m6P6Wr2_jde_AF1rn57JwzjmsRix3l5nHS78cLgn5UNDpewIEFognh0SnFS92roGcJhPDPB15YWJxK9ugmEr4B88IZ7ZF6qN/s1600/APRIL-05-David-Mayman-pilots-the-JB-10-Jetpack-flying-machine.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9iFBb7v6yB9eAGU0z4BOxfUJWDR2S4z17lSOYVii94ZB8m6P6Wr2_jde_AF1rn57JwzjmsRix3l5nHS78cLgn5UNDpewIEFognh0SnFS92roGcJhPDPB15YWJxK9ugmEr4B88IZ7ZF6qN/s400/APRIL-05-David-Mayman-pilots-the-JB-10-Jetpack-flying-machine.jpg" width="262" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Jetpack JB-10 new in 2016 flown single handed.</span></i></span></td></tr>
</tbody></table>
<br />
<a name='more'></a><br />
<br />
Here are some new videos about it. With about 10 minutes of flight time it is a great device.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2FIIw4py1c-dTTNmRWTe_NUxv6jD_mkTbSwC3TW5bLZ2n_IQRQ8ix3l0NtCVaYAyYmydHFtAszTG-CPNpTaHyud4jOO8e0kKyxSoOpoRbgnLJoiJg62dGiw6HZPwIy45oKa4HlvC5qVkN/s1600/maxresdefault.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2FIIw4py1c-dTTNmRWTe_NUxv6jD_mkTbSwC3TW5bLZ2n_IQRQ8ix3l0NtCVaYAyYmydHFtAszTG-CPNpTaHyud4jOO8e0kKyxSoOpoRbgnLJoiJg62dGiw6HZPwIy45oKa4HlvC5qVkN/s400/maxresdefault.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Jetpack JB-10 fly by</span></i></span></td></tr>
</tbody></table>
<br />
<br />
Looking forward the day when they interbreed the jetpack and the jetwing .. that would be the ultimate personal jet .. slow speed take-offs and landings using it as a jetpack and higher speed flying using it as a jetwing.<br />
<br />
<br />
YouTube video - <a href="https://youtu.be/nTw1pPvdPJI" target="_blank">"Jetpack JB10 flies for the first time in Europe"</a><br />
<br />
<br />
YouTube video - <a href="https://youtu.be/mcvrKRDmCko" target="_blank">"JetPack Aviation JB10 Principality of Monaco Flight #2.."</a><br />
<br />
Buzz Lightyear seems to be able to do it already (fly and make landings with it). Additionally he also makes a re-entry to some planet!<br />
<br />
<div style="text-align: center;">
<br /><iframe allowfullscreen="" frameborder="0" height="225" src="https://www.youtube.com/embed/EyGuBM1ELf4" width="400"></iframe>
</div>
<br />
<br />
<br />
<span style="color: #0c343d;"><b>RESOURCES</b></span><br />
<br />
/1/ YouTube<br />
<br />
<br />
<div style="text-align: center;">
* * *</div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-70817254633227296362016-10-12T10:30:00.003+01:002016-10-13T00:16:40.471+01:00New Tiny PC - Intel Compute StickThe new <a href="https://en.wikipedia.org/wiki/Intel_Compute_Stick" target="_blank">Intel Compute Stick</a> (2016) is a fully functional Windows PC with "HD" and memory and connects directly to the monitor's HDMI connector. It has USB and other ports in it, fully functional PC with minimal effort.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqr4-WVCKeVpQKSmjNKzx9CcRWM1g4Vk1x3Z4EVK2Jexk2Ml9uiXzsHiYYheOBLZL_Ibp0P55yj1TVJvl_jgxTOMLH_hH1S7k-5B2ZVp5YJ89o_rn-uaZOBBIyk-1ktOi89uINNe-Q7V4H/s1600/intel-compute-stick-3.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqr4-WVCKeVpQKSmjNKzx9CcRWM1g4Vk1x3Z4EVK2Jexk2Ml9uiXzsHiYYheOBLZL_Ibp0P55yj1TVJvl_jgxTOMLH_hH1S7k-5B2ZVp5YJ89o_rn-uaZOBBIyk-1ktOi89uINNe-Q7V4H/s400/intel-compute-stick-3.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Intel Compute Stick, small but fully functional PC (Windows) computer</span></i></span></td></tr>
</tbody></table>
<div class="separator" style="clear: both; text-align: center;">
</div>
<br />
<a name='more'></a><br />
Here are some videos about it from Intel.<br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-tv-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-tv-video.html </a><br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/intel-computestick-introduction-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/intel-computestick-introduction-video.html</a><br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/compute-stick-hdmi-display-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/compute-stick-hdmi-display-video.html</a><br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-core-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-core-video.html</a><br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/compute-sticks-with-core-m-processors-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/compute-sticks-with-core-m-processors-video.html</a><br />
<br />
<a href="http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-get-more-out-of-your-tv-video.html" target="_blank">http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick-get-more-out-of-your-tv-video.html</a> <br />
<br />
There are basically two types of sticks available: Atom processor and Core m3/m5 processor based sticks. Atom sticks are slower but also cheaper. The following picture illustrates the current market. The full product line is listed <a href="https://en.wikipedia.org/wiki/Intel_Compute_Stick#Versions" target="_blank">here</a>.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEyi6RsOT66yaY9Omaya6vhFyv0qHtZpp7mBxNa7iKASq20sdOS4MQbN0tEDM1axCHIxh89qqQcvzjX5zrMRZWN6lQkDejb0ur8Va7vQurK7C67qp4ABwuIB-ZqX9Y3rt8pdAsoUIkkHmX/s1600/Products_2016.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEyi6RsOT66yaY9Omaya6vhFyv0qHtZpp7mBxNa7iKASq20sdOS4MQbN0tEDM1axCHIxh89qqQcvzjX5zrMRZWN6lQkDejb0ur8Va7vQurK7C67qp4ABwuIB-ZqX9Y3rt8pdAsoUIkkHmX/s400/Products_2016.png" width="325" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Year 2016 Intel Compute Stick products and typical prices.</span></i></span></td></tr>
</tbody></table>
<br />
Finally the computer is so small that there is no problem to place it. For example behind the monitor or TV. The always interesting graphics capabilities are defined by "<a href="https://en.wikipedia.org/wiki/Intel_HD_and_Iris_Graphics" target="_blank">Intel HD Graphics</a>". If you are a game player you might choose the Core-m version of the product. <a href="https://youtu.be/3PTskWOz_ww" target="_blank">Here</a> is a game play with the Core-m3 processor.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5JVpNCYxej3pFg-xQDgt0gxKh9NH6FfF-NS4dH8wjyMe6aKeqjTxzuFuRHFBl64NfGzZMw2Fhs9MayCSaja9ZtEuaEBpDYEMG7pHFkTDmlZYEZmZTYby0ser9zUSkFZasvHwQUhxsaVQI/s1600/IntelComputeStick03.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="307" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg5JVpNCYxej3pFg-xQDgt0gxKh9NH6FfF-NS4dH8wjyMe6aKeqjTxzuFuRHFBl64NfGzZMw2Fhs9MayCSaja9ZtEuaEBpDYEMG7pHFkTDmlZYEZmZTYby0ser9zUSkFZasvHwQUhxsaVQI/s400/IntelComputeStick03.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">The Intel Compute Stick size is typically 37 x 103 mm and slim.</span></i></span></td></tr>
</tbody></table>
<br />
Inside the stick you will find lot of modern highly integrated circuits.<br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_-dOIW38hfiZOY6bSu0B9tk6i4wfD-_L8sShiVzJEqW_k3qphmeGTAQuKJu725sDa_6jpqK_-oiIHR0idmZZYMr0s3H9aVKAEXS3m2S_BiGOM61DmiZkhroMYuan0iuJ4YPOxdSGMBG6j/s1600/computestick.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_-dOIW38hfiZOY6bSu0B9tk6i4wfD-_L8sShiVzJEqW_k3qphmeGTAQuKJu725sDa_6jpqK_-oiIHR0idmZZYMr0s3H9aVKAEXS3m2S_BiGOM61DmiZkhroMYuan0iuJ4YPOxdSGMBG6j/s400/computestick.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Inside Intel Compute Stick</span></i></span></td></tr>
</tbody></table>
<br />
What will be the future? Do we maybe have a fully integrated single chip PC computer year 2026? Time will give us an answer.<br />
<br />
Here is an interesting test for a 99 $ Lenovo Ideacentre Stick 300 and shows that the <a href="https://en.wikipedia.org/wiki/4K_resolution" target="_blank">4 k video</a> streaming is ok.<br />
<br />
YouTube video: "<a href="https://youtu.be/Ug_qaGYImeI" target="_blank">Lenovo Ideacentre Stick 300 Unbox and Test</a> "<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSDOyKFuFPZ0VtTxHQqoIsw2OfnYNQLI_rEXdLX45ATqN6_laINC6OyyxJa1DPPEeU9haqJUod0RimXT4W6wKtZVTv96hCGTVktLujoyKTFJFmfitEVuX3ZYrmMobi0mZ4HJy_xtTcxE5H/s1600/Samsung_105_inch_Ultra_HD_4K_television.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgSDOyKFuFPZ0VtTxHQqoIsw2OfnYNQLI_rEXdLX45ATqN6_laINC6OyyxJa1DPPEeU9haqJUod0RimXT4W6wKtZVTv96hCGTVktLujoyKTFJFmfitEVuX3ZYrmMobi0mZ4HJy_xtTcxE5H/s400/Samsung_105_inch_Ultra_HD_4K_television.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Samsung UN105S9 105 inch ultra-high-definition 4K television.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
<span style="color: #0c343d;"><b>RESOURCES</b></span><br />
<br />
<br />
/1/ <a href="http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick.html">http://www.intel.com/content/www/us/en/compute-stick/intel-compute-stick.html</a><br />
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/2/ Intel information sites<br />
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/3/ Wikipedia<br />
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/4/ YouTube <br />
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<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-88220676704594578852016-10-01T01:00:00.001+01:002016-10-27T20:41:29.740+01:00LM Descent to the Moon - Part 4 - Descent Monitoring<span style="color: #0c343d;"><b>REAL-TIME DESCENT MONITORING AND ANALYSIS</b></span>
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During the real-time situation, monitoring of the spacecraft systems and of the
trajectory was performed continually both on board by the crew and on the ground by the
flight controllers. The real-time monitoring determined whether the mission was to be
continued or aborted, as established by mission techniques prior to flight. The real-time situation for the Apollo 11 descent is described here.
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm2fGaCSSwg5WeujXBv2nxf6_jSTCZdpCmHdqvbCrrwkYmlqXg3Y9sh6wVaaKR5JMO5ToH-D-wB3HOl6aSwNhnKZ8hatHzPSidmbH0_4NDFvDshzlgZHVUbYNRGa5yJxcoEDtRl2rhb0Dt/s1600/LM_DOI.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="392" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgm2fGaCSSwg5WeujXBv2nxf6_jSTCZdpCmHdqvbCrrwkYmlqXg3Y9sh6wVaaKR5JMO5ToH-D-wB3HOl6aSwNhnKZ8hatHzPSidmbH0_4NDFvDshzlgZHVUbYNRGa5yJxcoEDtRl2rhb0Dt/s400/LM_DOI.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">LM (Apollo 11) DOI (Descent Orbit Insertion) is done 180 degrees before PDI (Powered Descent Initiation)</span></i></span></td></tr>
</tbody></table>
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<a name='more'></a><br />
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<span style="color: #0c343d;"><b>Descent Orbit Insertion (DOI)
</b></span><br />
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The DOl maneuver is performed on the farside of the Moon at a position in the
orbit 180 degrees prior to the PDI (Powered Descent Initiation) and is, therefore, executed and monitored solely by the crew. Of major concern during the burn is the performance of the PGNCS (also called PGNS, Primary Guidance and Navigation [Sub]System) and the DPS (Descent Propulsion [Sub]System). The DOl maneuver is essentially a retrograde burn to reduce orbit altitude from approximately 60 nautical miles to 50 000 feet for the PDI and requires a velocity reduction of 75 fps.<br />
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This speed reduction is accomplished by throttling the DPS to 10-percent thrust for 15 seconds (for the center-of-gravity trimming) and to 40-percent thrust for 13 seconds. An over burn of 12 fps (or 3 seconds) would cause the LM to be on an impacting trajectory prior to PDI. Thus, the DOl is monitored by the crew with the AGS (Abort Guidance [Sub]System) during the burn and by range-rate tracking with the rendezvous radar (RR) immediately after the burn. If the maneuver is unsatisfactory, an immediate rendezvous with the CSM (Command Service Module) is performed with the AGS. For Apollo 11, this maneuver was nominal. Down-range residuals after the burn were 0.4 fps.
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<br />
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<span style="color: #0c343d;"><b>Powered Descent (PDI)</b></span><br />
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<u><span style="color: #cc0000;"><i><b>Trajectory limits</b></i></span>.</u> - During real time, trajectory limits are
monitored for flight
safety (green area in the following figure). The prime criterion for flight safety is the ability to abort
the descent at any time until the final decision to commit to touchdown.
Thus, flight dynamics limits are placed on altitude and altitude rate,
as shown below.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYkS6K16n3kvjjwILC25XAZ9zCN_XMzy_TMBFUP3dm8LIn5sm5gYAewFeIqAwsLAmC8f4iQj82xNxsxajZrxjkKRr44Kiftye7Ob4i81o2a5ZMC13pLiti8A8oIhkjhDiVRoQ2T65MI4Md/s1600/Finial_A11_Alt-Alt_rate_diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="372" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYkS6K16n3kvjjwILC25XAZ9zCN_XMzy_TMBFUP3dm8LIn5sm5gYAewFeIqAwsLAmC8f4iQj82xNxsxajZrxjkKRr44Kiftye7Ob4i81o2a5ZMC13pLiti8A8oIhkjhDiVRoQ2T65MI4Md/s400/Finial_A11_Alt-Alt_rate_diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Altitude as a function of altitude rate during powered descent</span></i></span>
</td></tr>
</tbody></table>
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Notice that the nominal trajectory design (blue curve) does not
approach the limits until late in the descent, after the crew has had
ample time for visual assessment of the situation. The limits shown are
based on APS (Abort Propulsion [Sub]System) abort with a 4-second free fall for crew action delay or on
DPS (Descent Propulsion [Sub]System) abort with a 20-second communications delay for ground
notification [<i>The abort limit line above is calculated using 20 s at any given sink rate</i>]. The flight controllers and the crew monitor altitude and
altitude rate, but because of communication delays with the ground, the
flight controllers only advise, based on projected trends. The profile shown in the above figure was near nominal (red curve).
<br />
<br />
<i>[A more accurate (?) descent trajectory can be found in the <u>Apollo 11 Mission Report</u>. The descent was measured by three computers: PGNS (onboard LM primary computer), AGS (on board secondary computer), and MSFN (Manned Space Flight Network on ground [Earth]). These three trajectories are shown in the following figure. It is worth to mention that there are several reasons these curves might not be accurate since for example the altitude was corrected 2200 ft (too low) manually during the descent (<u>Apollo 11 Experience Report</u>) and that correction was slowly applied by the computer(?s?). Most likely the PGNS curve might be the most close to the actual.]</i><br />
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<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEit85XvYdVyxOrRQjY9mtFlZ64rpAE2VOw6_Eiw4G4s9o7_KtuvaewLlKx0CeuS6vWXZeKyiGjEW1yoCdnOCOWC1XD1CDBUaxghyphenhyphendqP8GvYDE1NU15_b_-IwOBNwEKlPKZK7pWSHwfmnTw5/s1600/A11-Altitude-Altitude+rat+diagram.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEit85XvYdVyxOrRQjY9mtFlZ64rpAE2VOw6_Eiw4G4s9o7_KtuvaewLlKx0CeuS6vWXZeKyiGjEW1yoCdnOCOWC1XD1CDBUaxghyphenhyphendqP8GvYDE1NU15_b_-IwOBNwEKlPKZK7pWSHwfmnTw5/s400/A11-Altitude-Altitude+rat+diagram.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">A (maybe more) accurate altitude vs altitude rate figure from the <u>Apollo 11 Mission Report 1969</u></span></i></span></td></tr>
</tbody></table>
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<i><a href="https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule" target="_blank">[The 3-sigma curves</a> are calculated using standard 3-sigma dispersions. The following figure shows that almost all cases are inside the 3-sigma curves for a nominal line.]</i><br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCtzhKuCY75J7roSN39dttNxMbIBzS2NC51DnYYtht2DM8Nn6OUTePPnCsGS2tyJaC8EIWorVsvradHTkH3m-aPLEB9TbQrSkuWKG8DkSYcodaSs2X9thSp5ku7joJpRrOFYGrw2zT2fJb/s1600/3-Sigma_etc.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiCtzhKuCY75J7roSN39dttNxMbIBzS2NC51DnYYtht2DM8Nn6OUTePPnCsGS2tyJaC8EIWorVsvradHTkH3m-aPLEB9TbQrSkuWKG8DkSYcodaSs2X9thSp5ku7joJpRrOFYGrw2zT2fJb/s400/3-Sigma_etc.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">99.7 % of the standard distributed cases are inside the +/-3-sigma limit lines.</span></i></span></td></tr>
</tbody></table>
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<span style="color: #cc0000;"><i><b><u>The DPS and PGNCS interface.</u></b></i></span> - To determine in real time if the DPS is providing
sufficient thrust to achieve the guidance targets, the flight controllers monitor a plot of guidance thrust command (GTC) as a function of horizontal velocity, as shown below.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIfcJnsbjXK30CtG3airHvD60sYsasozBCt6J49ThFBOaYgZZSLoEEugzoX-vVLSh-igYuEquIYDEGyACdFLhy35zB-QHC2mEVOm8owp4m92dQGe48SzSICsPyY2Kf8IFw9uJ65tPpNSGo/s1600/GTC_vs_Vh__.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="298" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhIfcJnsbjXK30CtG3airHvD60sYsasozBCt6J49ThFBOaYgZZSLoEEugzoX-vVLSh-igYuEquIYDEGyACdFLhy35zB-QHC2mEVOm8owp4m92dQGe48SzSICsPyY2Kf8IFw9uJ65tPpNSGo/s400/GTC_vs_Vh__.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Guidance thrust command (GTC) as a function of horizontal velocity.
</span></i></span></td></tr>
</tbody></table>
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Nominally, the GTC decreases almost parabolically from an initial value near 160 percent of design thrust to the throttleable level of 57 percent, approximately 2 minutes (horizontal velocity being 1400fps) before high gate (horizontal velocity being 500 fps). If the DPS produces off-nominal high thrust, horizontal velocity is being reduced more rapidly than desired to reach high-gate conditions. Therefore, the GTC drops to 57 percent earlier with a higher-than-nominal velocity to guide to the desired position and velocity targets. This early throttledown (also called throttle recovery) results in propellant inefficiency.<br />
<br />
If the DPS produces off-nominal low thrust, horizontal velocity is not being reduced rapidly enough. Therefore, the GTC drops to 57 percent later at a lower velocity to guide to the desired position and velocity. This later throttledown results in increased propellant efficiency (I. e., longer operation at maximum thrust). However, if no throttle down occurs prior to high gate (program switch from P63 to P64), the targets will not be satisfied, and the resulting trajectory may not be satisfactory from the standpoint of visibility.<br />
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaWiZkbKWPCosofE6jY9b4Ny4FqH9c2k49JhIY0levXm9L2tF-H__9_w0BQHwdWqM745MLZierS4CLPs39CwjAevjhAlaWaejR43kviJh_l98lF7JAt-1mVJyMXWOqfFxr807MT6L-G31G/s1600/Duke%252C_Lovell_and_Haise_at_the_Apollo_11_Capcom%252C_Johnson_Space_Center%252C_Houston%252C_Texas.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="268" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaWiZkbKWPCosofE6jY9b4Ny4FqH9c2k49JhIY0levXm9L2tF-H__9_w0BQHwdWqM745MLZierS4CLPs39CwjAevjhAlaWaejR43kviJh_l98lF7JAt-1mVJyMXWOqfFxr807MT6L-G31G/s400/Duke%252C_Lovell_and_Haise_at_the_Apollo_11_Capcom%252C_Johnson_Space_Center%252C_Houston%252C_Texas.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">CAPCOM Charles Duke, with backup pilots <a href="https://en.wikipedia.org/wiki/Jim_Lovell" target="_blank" title="Jim Lovell">James Lovell</a> and <a href="https://en.wikipedia.org/wiki/Fred_Haise" target="_blank" title="Fred Haise">Fred Haise</a> listening in during Apollo 11's descent</span></i></span></td></tr>
</tbody></table>
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In fact, for extremely low thrust, the guidance solution for the GTC can diverge (previous figure curves 9400 and 9350); as TGO (Time to Go) becomes small, the guidance calls for more and more thrust in order to achieve its targets. This divergence can result in an unsafe trajectory, one from which an abort cannot be satisfactorily performed. The 2-minute bias for throttle recovery before high gate provides sufficient margin for 3-sigma low thrust even with propellant valve malfunction. However, the flight controllers monitor the GTC to assure satisfactory interface between DPS and PGNCS operation. A mission rule was established that called for an abort based on the GTC divergence. During the Apollo 11 landing, the DPS thrust was nearly nominal; thus, no DPS and PGNCS interface problems were encountered.
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<span style="color: #cc0000;"><i><b><u>The LR and PGNCS interface.</u></b></i></span> - Normally, the LR (Landing Radar) update of the PGNCS altitude estimate is expected to occur by crew input (always manually updated by te crew) at an altitude of 39 000 ± 5000 feet (3-sigma dispersion). Without LR altitude updating, system and navigation errors are such that the descent cannot be safely completed. In fact, it is unsafe to try to achieve high gate where the crew can visually assess the approach without altitude updating. Thus, a mission rule for real-time operation was established that called for aborting the descent at a PGNCS-estimated altitude of 10,000 feet, if LR altitude updating had not been established.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTSfNwuOMneZlJz9br8Md4gM_dpm0RcNspa5Xq8DirsQP4m4JoTe0VWEcYZEIUUsrs0ukFKnU5IYyTiheP4Qf7bOL0EydgHCwPmjl6OLFZynqMxktjiniABlLfqOUpAPg4FJfIF9RZ4ecs/s1600/LM_Landing+Radar_%2528LR%2529.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjTSfNwuOMneZlJz9br8Md4gM_dpm0RcNspa5Xq8DirsQP4m4JoTe0VWEcYZEIUUsrs0ukFKnU5IYyTiheP4Qf7bOL0EydgHCwPmjl6OLFZynqMxktjiniABlLfqOUpAPg4FJfIF9RZ4ecs/s400/LM_Landing+Radar_%2528LR%2529.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">The Landing Radar antenna was located under the LM.</span></i></span></td></tr>
</tbody></table>
<br />
In addition to the concern for the time that initial altitude updating occurs is the concern for the amount of altitude updating (I. e., the difference between PGNCS and LR altitude determinations dh). If the LM is actually higher than the PGNCS estimate, the LR will determine the discrepancy and update the PGNCS. The guidance then tries to
steer down rapidly to achieve the targets. As a result of the rapid changes, altitude
rates may increase to an unsafe level for aborting the descent. That is, should an abort be required, the altitude rates could not be nulled by the ascent engine in time to prevent surface collision.<br />
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The dh limits necessary to avoid these rates are shown below.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhISylxYhHroqaKIYfxP0JhjTT5GTgSPl83N3y9MH4GBV3EQcyFOvaNCvKnTigbUDYEJOOUAMYQqlMNGP9DUMtD_q7vetm2BL_-9vg8dZa9-mybGl3ZGwkhxr4rXYmIefBR57Zw3wi8_vCO/s1600/LR_updates.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhISylxYhHroqaKIYfxP0JhjTT5GTgSPl83N3y9MH4GBV3EQcyFOvaNCvKnTigbUDYEJOOUAMYQqlMNGP9DUMtD_q7vetm2BL_-9vg8dZa9-mybGl3ZGwkhxr4rXYmIefBR57Zw3wi8_vCO/s400/LR_updates.png" width="363" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Landing radar altitude updates.</span></i></span>
</td></tr>
</tbody></table>
<br />
<br />
Notice that over the estimated 3-sigma region of LR initial updating (which at the time of that analysis was centered at an altitude of only 35 600 feet instead of 39 000 feet), the dh limits are much greater than the 3-sigma navigation estimates of dh.<br />
<br />
However, the flight controllers, as well as the crew, monitor dh to assure that the boundary is not exceeded before incorporation of the LR altitude updating. If the boundary is exceeded, then the data are not incorporated, and an abort is called. When the LM is actually lower than estimated, no excessive rates are encountered upon LR updating. It is necessary only that the LM altitude and altitude rate be above the abort limits, defined in the above section entitled "Trajectory Limits."
<br />
<br />
<br />
During the Apollo 11 mission, the LR acquired lock-on to the lunar surface during
the rotation to face-up attitude at an altitude of 37,000 feet. The dh was -2200 feet,
indicating that the LM was actually low.<br />
<br />
<span style="color: #274e13;"><i>[Some sources say that the Apollo 11 LM PDI was at 52,000 ft instead of the nominal 50,000 ft, indicating that LM was 2,000 ft high. - If this information here is correct then the PDI altitude was most likely 48,000 ft instead of the nominal 50,000 ft assumetd at the PDI.]</i></span><br />
<br />
This small amount of dh can readily be attributed to terrain variations. Because no limits were violated, the data were incorporated after a short period of monitoring at an altitude of 31,600 feet. The dh readily converged to a small value of 100 feet within 30 seconds. The LR velocity updates were incorporated nominally, beginning at a 29,000 foot altitude. As expected, LR signal dropouts were encountered at low altitudes (below 500 feet) but presented no problem. When the velocity becomes small along the LR beams, depending on the attitude and approach velocity, zero Doppler shift is encountered; hence, no signal occurs.
<br />
<br />
<br />
<span style="color: #cc0000;"><i><b><u>Crew visual assessment.</u></b></i></span> - As stated previously, the approach and landing phases
have been designed to provide crew visibility of the landing area. This provision allows the crew to assess the acceptability of the landing area, to decide to continue toward the landing area, or to redesignate a landing away from it with LPD or manual control. During the Apollo 11 mission, because of the initial navigation errors, the descent was guided into the generally rough area surrounding West Crater (se below).<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtxTKS_tZ3-x4tNDEnrCyZ5V9dM0EhL7avMzvF6R1y9Qd2AF555jlxMmw-wRLpJXxqr8z_g1TsaH82FQf3AxtOWWY3ggO36jX14H-goghyphenhyphenTgqLaTsuA2myLWK3J7HrBlXzgs-LkLXWh8xJ/s1600/A11_LM_Final.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="396" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhtxTKS_tZ3-x4tNDEnrCyZ5V9dM0EhL7avMzvF6R1y9Qd2AF555jlxMmw-wRLpJXxqr8z_g1TsaH82FQf3AxtOWWY3ggO36jX14H-goghyphenhyphenTgqLaTsuA2myLWK3J7HrBlXzgs-LkLXWh8xJ/s400/A11_LM_Final.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo 11 LM final approach, West Crater in the center.</span></i></span></td></tr>
</tbody></table>
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<br />
West Crater is inside the premission mapped area, approximately 3 nautical miles west of center. Unfortunately, because of the guidance program alarms, the commander was unable to concentrate on the window view until late in the descent (near low gate). Thus, crew visual assessment during the approach phase was minimal, which resulted in continued approach into the West Crater area.<br />
<br />
<br />
<span style="color: #cc0000;"><i><b><u>The PGNCS monitoring.</u></b></i></span> - To determine degraded performance of the PGNCS, the
ground flight controllers continually compare the LM velocity components computed by
the PGNCS with those computed by the AGS and with those determined on the ground
through Manned Space Flight Network (MSFN) tracking. That is, a two-out-of-three
voting comparison logic is used to determine whether the PGNCS or the AGS is degrading. Limit or red lines for velocity residuals between the PGNCS and the MSFN
computations and between the PGNCS and the AGS computations are established before
the mission, based on the ability to abort on the PGNCS to a safe (30,000-footperilune)
orbit.
<br />
<br />
In real time, the Apollo 11 PGNCS and AGS performance
was close to nominal;
however, a large velocity difference in the radial direction of 18 fps
(limit line at 35 fps) was detected at PDI and remained constant well
into the burn. This error did not indicate a systems performance
problem, but rather an initialization error in down-range position. This
effect is illustrated geometrically in the next figure.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEVQMIzk0V5ha_6WBW5QU0MzPEz5NQrlxUVsf20u69BM67YbIAOfnnoPKHS_DxVlhzO4WXFc-slp3lmQQn1WYm_8RxHxOmpshNElv0cjqY_pn3e6ycPHBMANKOPwmIwsH-BZhEW8AKFr0N/s1600/Pos_err_vs_vel_comp.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEVQMIzk0V5ha_6WBW5QU0MzPEz5NQrlxUVsf20u69BM67YbIAOfnnoPKHS_DxVlhzO4WXFc-slp3lmQQn1WYm_8RxHxOmpshNElv0cjqY_pn3e6ycPHBMANKOPwmIwsH-BZhEW8AKFr0N/s400/Pos_err_vs_vel_comp.png" width="386" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Effect of position error on velocity comparison.
</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The PGNCS position vector RE and velocity vector VE estimates are
used to initiate the MSFN powered-flight processor. The MSFN directly
senses the actual velocity VA at the actual position RA' but, having
been initialized by the PGNCS state, the MSFN applies VA at RE. Thus, a
flight-path-angle error dy is introduced by a down-range position error
and shows up as a radial velocity difference dVDIFF.<br />
<br />
The
magnitude of the velocity difference indicates that the Apollo 11 LM
down-range position was in error by approximately 3 nautical miles at
PDI and throughout the powered descent to landing. The reason for the
down-range navigation error was attributed to several small dV inputs to
the spacecraft state in coasting flight. These inputs were from
uncoupled RCS attitude maneuvers and cooling system venting not
accounted for in the prediction of the navigated state at PDI.
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJP33FUNVGF9RiVAN1QpH52NKFFP0uRULw7QEWdsCHsWIyDnTwKPUEvBOF7oWHUdn3RutSZOfbsPV_Up2eXO0b7MMD3LGa6wc4olNlOSO9M1gOPdW4m5gQtBNqepfVJs7JsrA6FuFcmSNc/s1600/LM_PGNS.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJP33FUNVGF9RiVAN1QpH52NKFFP0uRULw7QEWdsCHsWIyDnTwKPUEvBOF7oWHUdn3RutSZOfbsPV_Up2eXO0b7MMD3LGa6wc4olNlOSO9M1gOPdW4m5gQtBNqepfVJs7JsrA6FuFcmSNc/s400/LM_PGNS.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">LGC was located at the back of the LM.</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The LM guidance computer (LGC) also monitors the speed
at which it is performing computation tasks: navigation, guidance, displays, radar data
processing, and
auxiliary tasks. If the computer becomes overloaded or falls behind in
accomplishing
these tasks, an alarm is issued to inform the crew and the flight
controllers, and priorities are established so that the more important
tasks are accomplished first. This
alarm system is termed "computer restart protection."<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYw5Zzx0BBQ-HEucTM0o7RlSFGC9EZYD_1X1BhViFTLzBIrx-INzdo9JWH55qspAl2hRXArXPrlqJ8oVCoT19aUFmRFOYvsLuBpmpQjdxybXIRXzvbXt3urpVxyzVnV1HfPWFQuN6jy_6T/s1600/1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYw5Zzx0BBQ-HEucTM0o7RlSFGC9EZYD_1X1BhViFTLzBIrx-INzdo9JWH55qspAl2hRXArXPrlqJ8oVCoT19aUFmRFOYvsLuBpmpQjdxybXIRXzvbXt3urpVxyzVnV1HfPWFQuN6jy_6T/s400/1.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo Guidance Computer (AGC) or LM Guidance Computer (LMC) and DSKY.</span></i></span></td></tr>
</tbody></table>
<br />
During real time,
because of
an improperly defined interface, a continuous signal was issued to the
LGC from the
RR (Rendezvous Radar) through coupling data units (CDU's). These signals caused the LGC to count
pulses continually in an attempt to slew the RR until a computation time
interval was exceeded. As
a result, the alarm was displayed and computation priorities were
executed by the computer. The alarm was quickly interpreted, and
flight-control monitoring indicated that guidance and navigation
functions were being performed properly; thus, the descent was
continued. In spite of the initial position error and the RR inputs, the
PGNCS performed excellently during the Apollo 11 powered descent.
<br />
<br />
<br />
<span style="color: #0c343d;"><b>RESOURCES</b></span><br />
<br />
/1/ Bennett, Floyd V., Manned Spacecraft Center (MSC) - Apollo Experience Report - Mission Planning for Lunar Module Descent and Ascent<br />
<br />
/2/ Wikipedia<br />
<br />
/3/ Apollo 11 Mission Report 1969, NASA<br />
<br />
/4/ Apollo Experience Report(s) <br />
<br />
<div style="text-align: center;">
* * *</div>
Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-56939453797941766742016-09-24T23:40:00.002+01:002016-09-24T23:49:05.368+01:00The US Senate Demands NASA: "Go to Mars"“<i>Fifty-five years after President Kennedy challenged the nation to put a man on the moon, the Senate is challenging NASA to put humans on Mars. The priorities that we’ve laid out for NASA in this bill mark the beginning of a new era of American spaceflight,</i>” said an optimistic Florida Sen. Bill Nelson, senior Democrat on the Commerce panel.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjc8v7y2ExDVo2YoD409hljgXT8U2kDhah16v7Djq9VIy421G-dKvPuY52szAh7-7QRT_yCC6GunpYcnDWsG-DzzxWE8-g4PvLu4pMARcRLyvBnjmiAmaFpSbNtreaPIxVAaNSoaNv6DalT/s1600/Bill_Nelson%252C_official_NASA_photo.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjc8v7y2ExDVo2YoD409hljgXT8U2kDhah16v7Djq9VIy421G-dKvPuY52szAh7-7QRT_yCC6GunpYcnDWsG-DzzxWE8-g4PvLu4pMARcRLyvBnjmiAmaFpSbNtreaPIxVAaNSoaNv6DalT/s400/Bill_Nelson%252C_official_NASA_photo.jpg" width="340" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Senator Bill Nelson was also a NASA <a href="https://en.wikipedia.org/wiki/Payload_Specialist" target="_blank" title="Payload Specialist">Payload Specialist</a> on <a href="https://en.wikipedia.org/wiki/Space_Shuttle" target="_blank" title="Space Shuttle">Space Shuttle</a> <a href="https://en.wikipedia.org/wiki/Space_Shuttle_Columbia" target="_blank" title="Space Shuttle Columbia">Columbia</a>'s <a href="https://en.wikipedia.org/wiki/STS-61-C" target="_blank" title="STS-61-C">STS-61-C</a> mission from January 12 to 18, 1986.</span></i></span></td></tr>
</tbody></table>
<br />
The Senate is not giving NASA money just for the sake of exploration. It is also a challenge, a mandate, actually. The bill requires that NASA make it an official goal to send crewed missions to Mars in the next 25 years.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdz-WYP1hNO19la_FXCeD_v8zkSXxfYLWYptS6OKg1iqpS4NxzcPFpPrtl8cRaVBViwvNueFq0AR7OPqNaWuEAIv_Wt1oWUVERJk9cYvDhV8j4YZupBTFOoITXyvp0FolAAL7Rs-59K7ky/s1600/NASA-Budget-Federal.svg.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="260" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdz-WYP1hNO19la_FXCeD_v8zkSXxfYLWYptS6OKg1iqpS4NxzcPFpPrtl8cRaVBViwvNueFq0AR7OPqNaWuEAIv_Wt1oWUVERJk9cYvDhV8j4YZupBTFOoITXyvp0FolAAL7Rs-59K7ky/s400/NASA-Budget-Federal.svg.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">NASA's budget vs. federal budget</span></i></span></td></tr>
</tbody></table>
<br />
<br />
The Senate is not giving more money. The NASA' budget will stay about the same as before, about 0.5 % of the <a href="https://en.wikipedia.org/wiki/2011_United_States_federal_budget" target="_blank">United States federal budget</a>. They are just giving more orders at this time. The NASA funding reached its peak during the Apollo era 1966, almost 4.5 % of the federal budget. <br />
<br />
<br />
<span style="color: #0c343d;"><b>RESOURCES</b></span><br />
<br />
/1/ <a href="http://futurism.com/its-official-were-going-to-mars/" target="_blank">"It’s Official: We’re Going to Mars" - http://futurism.com</a><br />
<br />
<br />
<div style="text-align: center;">
* * *</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-38759751227069785572016-08-09T00:47:00.001+01:002016-08-10T19:45:35.202+01:00Orbit Calculator (Circular)<script language="JavaScript">
<!-- begin
// global variables
var G = 6.67408e-11;
var pi = 3.14159265358979323846;
// Plane masses in kg
var Mme = 3.301e23;
var Mve = 4.867e24;
var Mea = 5.972e24;
var Mlu = 7.346e22;
var Mma = 6.417e23;
var Mju = 1.899e27;
var Msa = 5.685e26;
var Mur = 8.682e25;
var Mne = 1.024e26;
// Planet radiuses in m
var Rme = 2440.0e3;
var Rve = 6052.0e3;
var Rea = 6378.0e3;
var Rlu = 1738.0e3;
var Rma = 3397.0e3;
var Rju = 71492.0e3;
var Rsa = 60268.0e3;
var Rur = 25559.0e3;
var Rne = 24766.0e3;
var planetRadius = Rea;
var planetMass = Mea;
function compute1()
{
// Compute v and T from h
var satAltitude = parseFloat(document.worksheet1.varB.value);
var R = planetRadius + satAltitude;
var speed = Math.sqrt((G*planetMass)/R);
var period = Math.sqrt((4.0*pi*pi*R*R*R)/(G*planetMass));
document.worksheet1.varC.value = Math.round( speed * 100 ) / 100;
document.worksheet1.varD.value = Math.round( period * 100 ) / 100;
document.worksheet1.varG.value = Math.round( (period/60.0) * 100 ) / 100;
document.worksheet1.varH.value = Math.round( (speed/1000.0) * 100 ) / 100;
document.worksheet1.varI.value = Math.round( (satAltitude/1000.0) * 100 ) / 100;
}
function compute2()
{
// Compute h and T from v
var speed = parseFloat(document.worksheet1.varC.value);
var R = G*planetMass/(speed*speed);
var period = Math.sqrt((4.0*pi*pi*R*R*R) / (G*planetMass));
var satAltitude = R - planetRadius;
document.worksheet1.varB.value = Math.round( satAltitude * 100 ) / 100;
document.worksheet1.varD.value = Math.round( period * 100 ) / 100;
document.worksheet1.varG.value = Math.round( (period/60.0) * 100 ) / 100;
document.worksheet1.varH.value = Math.round( (speed/1000.0) * 100 ) / 100;
document.worksheet1.varI.value = Math.round( (satAltitude/1000.0) * 100 ) / 100;
}
function compute3()
{
// Compute h and v from T
var period = parseFloat(document.worksheet1.varD.value);
var R = Math.pow((period*period*G*planetMass / (4.0*pi*pi)),(1.0/3.0));
var satAltitude = R - planetRadius;
var speed = Math.sqrt((G*planetMass)/R);
document.worksheet1.varB.value = Math.round( satAltitude * 100 ) / 100;
document.worksheet1.varC.value = Math.round( speed * 100 ) / 100;
document.worksheet1.varG.value = Math.round( (period/60.0) * 100 ) / 100;
document.worksheet1.varH.value = Math.round( (speed/1000.0) * 100 ) / 100;
document.worksheet1.varI.value = Math.round( (satAltitude/1000.0) * 100 ) / 100;
}
function useMe()
{
planetRadius = Rme;
planetMass = Mme;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useVe()
{
planetRadius = Rve;
planetMass = Mve;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useEa()
{
planetRadius = Rea;
planetMass = Mea;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useLu()
{
planetRadius = Rlu;
planetMass = Mlu;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useMa()
{
planetRadius = Rma;
planetMass = Mma;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useJu()
{
planetRadius = Rju;
planetMass = Mju;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useSa()
{
planetRadius = Rsa;
planetMass = Msa;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useUr()
{
planetRadius = Rur;
planetMass = Mur;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function useNe()
{
planetRadius = Rne;
planetMass = Mne;
document.worksheet1.varF.value = planetRadius;
document.worksheet1.varE.value = planetMass;
}
function denyEntry() {
// tell user can't enter this field
alert("This is a computed field; you can't change its value.");
}
// end
</script>
<br />
<center>
<h2>
Orbit Calculator</h2>
<form name="worksheet1">
<table align="center">
<tbody>
<tr>
<td align="right"><table align="center" border="">
<tbody>
<tr>
<td>Planet
</td>
<td><input name="aaa" onclick="useMe()" type="radio" />Mercury <br />
<input name="aaa" onclick="useVe()" type="radio" />Venus <br />
<input checked="" name="aaa" onclick="useEa()" type="radio" />Earth <br />
<input name="aaa" onclick="useLu()" type="radio" />Moon <br />
<input name="aaa" onclick="useMa()" type="radio" />Mars <br />
<input name="aaa" onclick="useJu()" type="radio" />Jupiter <br />
<input name="aaa" onclick="useSa()" type="radio" />Saturn <br />
<input name="aaa" onclick="useUr()" type="radio" />Uranus <br />
<input name="aaa" onclick="useNe()" type="radio" />Neptune </td>
<td>Around which<br />
the satellite<br />
orbits.<br />
<br />
Currently using<br />
Mass<br />
<input disabled="" name="varE" readonly="" size="10" type="text" value="5.972e+24" /> kg<br />
Radius<br />
<input disabled="" name="varF" readonly="" size="10" type="text" value="6378000" /> m</td>
</tr>
<tr>
<td>Altitude [h]</td>
<td><input name="varB" onchange="compute1()" size="10" type="text" value="413000.0" /> m
</td>
<td><input disabled="" name="varI" readonly="" size="10" type="text" value="413.00" /> km
</td>
</tr>
<tr>
<td>Speed [v]</td>
<td><input name="varC" onchange="compute2()" size="10" type="text" value="7661.0" /> m/s
</td>
<td><input disabled="" name="varH" readonly="" size="10" type="text" value="7.66" /> km/s
</td>
</tr>
<tr>
<td>Period [T]</td>
<td><input name="varD" onchange="compute3()" size="10" type="text" value="5570.0" /> s
</td>
<td><input disabled="" name="varG" readonly="" size="10" type="text" value="92.83" /> min
</td>
</tr>
</tbody>
</table>
<br />
<input name="ComputeButn1" onclick="compute1()" type="button" value="Solve v T using h" />
<input name="ComputeButn2" onclick="compute2()" type="button" value="Solve h T using v" />
<input name="ComputeButn3" onclick="compute3()" type="button" value="Solve h v using T" />
</td></tr>
</tbody>
</table>
</form>
<i>You need a
<a href="http://enable-javascript.com/">
JavaScript</a>-capable browser.</i></center>
<center>
<i> </i>
<br />
</center>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRssHGXY0xyzzC3R8sz9RBfw_BX6a5q1kwZ5KTW8PpfSr-X426P9NF31HZAmlW1UM6ue7D6Vcbv9bTR4nV5jAXX4h5oB_bodm6KhVumgo6PSHF3y8pYnrwjQ082iWx0oxd3j3bMxaUvkTw/s1600/Circular_Orbit.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRssHGXY0xyzzC3R8sz9RBfw_BX6a5q1kwZ5KTW8PpfSr-X426P9NF31HZAmlW1UM6ue7D6Vcbv9bTR4nV5jAXX4h5oB_bodm6KhVumgo6PSHF3y8pYnrwjQ082iWx0oxd3j3bMxaUvkTw/s400/Circular_Orbit.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Circular orbit variables</span></i></span></td></tr>
</tbody></table>
<span style="font-size: large;"><b></b></span><br />
<span style="font-size: large;"><b></b></span><br />
<hr />
<span style="font-size: large;"><b></b></span><br />
<a name='more'></a><span style="font-size: large;"><b><br /></b></span>
<span style="font-size: large;"><b>Instructions (<a href="https://en.wikipedia.org/wiki/Circular_orbit" target="_blank">Circular Orbit</a>)</b></span><br />
<br />
<br />
Default values show ISS orbit around Earth. Its average altitude
h is 413 km. Orbital speed v is 7.66 km/s and period T is 92.69
min (5561 s). Since ISS specifications agree with the calculator
output the calculation is correct (at least for Earth).
<br />
<br />
Choose the planet that is circulated by the satellite. This will define the planet's radius and mass. Then enter the orbit altitude in meters or the speed in m/s or the period in seconds. Then press any of the three calculate buttons. Any button will calculate 2 unknows using the one parameter given.<br />
<br />
<b>Height units</b> are m, <b>Velocity units</b> are m/s, <b>Altitude units</b> are m.
<br />
<br />
The script shows the planet constants used (mass and radius) and results are converted to some more common units also.
<br />
<div style="text-align: center;">
* * *</div>
<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0tag:blogger.com,1999:blog-2952170560031258599.post-52849764276760216502016-08-01T22:16:00.000+01:002016-08-03T10:04:04.122+01:00LM Descent to the Moon - Part 3 - Practice (Apollo 11, 1969)<b><span style="color: #0c343d;">APOLLO 11 DESCENT AND LANDING SUMMER 1969</span></b><br />
<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSDBybJOzdd3d_rB5Qf-begXy8weZ5401FZpsyy5WIRlvgrJStnw_vgCXncqmjfp-YPLGBD64pGNUH2Fk9kVZN4VTJKTYnkZVjXRZs4jAqzMkYU7mY3EfrhIowckl5QQDuBndj2EE2NUX-/s1600/February+24,+1970,+Russell+A.+Larson+and+David+G.+Hoag+.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="323" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiSDBybJOzdd3d_rB5Qf-begXy8weZ5401FZpsyy5WIRlvgrJStnw_vgCXncqmjfp-YPLGBD64pGNUH2Fk9kVZN4VTJKTYnkZVjXRZs4jAqzMkYU7mY3EfrhIowckl5QQDuBndj2EE2NUX-/s1600/February+24,+1970,+Russell+A.+Larson+and+David+G.+Hoag+.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000; font-size: small;"><i>Feb. 24, 1970, Russell A. Larson (left, Massachusetts Institute of Technology project manager for the lunar module flight program) and David G. Hoag (director of the Apollo Group at MIT’s Draper Lab) in the LM mock-up or simulator.</i></span></td></tr>
</tbody></table>
<br />
<a name='more'></a><br />
<br />
<i><span style="color: #274e13;">[Don Eyles: "The Apollo 11 mission succeeded in landing on the moon despite two </span></i><i><span style="color: #274e13;">computer-related problems that affected the Lunar Module during the powered </span></i><i><span style="color: #274e13;">descent. An uncorrected problem in the rendezvous radar (RR) interface stole </span></i><i><span style="color: #274e13;">approximately 13% of the computer's duty cycle, resulting in five (1201 and </span></i><i><span style="color: #274e13;">1202) program alarms and software restarts during the descent. In a less </span></i><i><span style="color: #274e13;">well-known problem, caused by erroneous data, the thrust of the LM's descent </span></i><i><span style="color: #274e13;">engine fluctuated wildly because the throttle control algorithm was only </span></i><i><span style="color: #274e13;">marginally stable."]</span></i><br />
<br />
<br />
<b><span style="color: #0c343d;">Apollo 11 (LM-5) /5/</span></b><br />
<br />
At landing, the quantity of propellants remaining in each of the four tanks was as follows.<br />
<br />
1. Oxidizer tank 1 : 5.7 percent<br />
2. Oxidizer tank 2: 2.7 percent<br />
3. Fuel tank 1: 3.9 percent<br />
4. Fuel tank 2: 3.9 percent<br />
<br />
The minimum-usable quantities, based on the indication of oxidizer tank 2, allowed a remaining hover time of 63.5 seconds.<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJTtLrpdDMQVqXP3r5-nH06XV9hJR5VFCRhX5bWxagprjoXfxjeZwJp9GTGPeO6-JILtG4wssOiOUYRbz9dV-sLicYYbib8WIVo9SH95IWLVJ4rOp9fqbMo4OKkuOdjl3ZgU2ddk1Jdh3n/s1600/Apollo_11_LM_Descent_Hover_Phase.PNG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="336" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJTtLrpdDMQVqXP3r5-nH06XV9hJR5VFCRhX5bWxagprjoXfxjeZwJp9GTGPeO6-JILtG4wssOiOUYRbz9dV-sLicYYbib8WIVo9SH95IWLVJ4rOp9fqbMo4OKkuOdjl3ZgU2ddk1Jdh3n/s1600/Apollo_11_LM_Descent_Hover_Phase.PNG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><i><span style="color: #cc0000; font-size: small;">Apollo 11 landing throttle profile</span></i></td></tr>
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During the last 140 seconds of the PDI burn (hover phase), a series of large oscillating-throttle changes occurred (figure above). These changes were approximately 15 percent peak-to-peak about a nominal throttle setting of approximately 26 percent.<br />
<br />
Large and rapid changes in vehicle attitudein pitch during the final phases of landing (<i><span style="color: #274e13;">Eyles: "Armstrong switched the autopilot from AUTO to ATT HOLD to manually fly over the rocky area"</span></i>) caused centrifugal accelerations on the inertial- measurement-unit accelerometers located at the top of the ascent stage high above the vehicle c.g., thereby giving a false indication of vertical acceleration. This false indication caused the lunar guidance computer to command a throttle change to compensate for an unreal change in vertical acceleration. Later, this problem was investigated under the analysis of the guidance and control system.<br />
<br />
<i><span style="color: #274e13;">[The oscillatory character of the P66 throttle command
was apparently due to the actual value of the descent
engine time constant being smaller than that assumed.
And so it was: the performance of the descent engine
had been improved, but the ICD was not modified
accordingly. The actual time lag for the descent engine
was only about 0.075 seconds when it was assumed to be
0.3 seconds. Despite of that both Apollo 11 and 12 flew
with 0.2 seconds of compensation for a 0.3 second throttle
delay. As a result the throttle was barely stable (until
later missions 14, 15, 16 and 17).]</span></i><br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDU8sRFnG4OqOYAsaRpKRAufQ7zQuy8ey7GdmGFdAeAnlDzNd2NGlsUhAzSeewRx_LsmqMWYTHeke0ARjT0ky4FwbK_taGVygLTZDqatyZSOBg-iX3m-Zglmwjt1-l4dOxmij6W5Ib365B/s1600/LM_Landing_945.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjDU8sRFnG4OqOYAsaRpKRAufQ7zQuy8ey7GdmGFdAeAnlDzNd2NGlsUhAzSeewRx_LsmqMWYTHeke0ARjT0ky4FwbK_taGVygLTZDqatyZSOBg-iX3m-Zglmwjt1-l4dOxmij6W5Ib365B/s400/LM_Landing_945.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">An artist's view of the final phase of the lunar landing</span></i></span></td></tr>
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<b><span style="color: #0c343d;">Apollo 11 Descent Events Timing</span></b><br />
<br />
There are many written list, audio tapes and videos about the Apollo 11 landing events available from various sources. Maybe the following YouTube video is the most informative of them all.<br />
<br />
YouTube video: <a href="https://youtu.be/RONIax0_1ec" target="_blank">"Apollo 11 landing from PDI to Touchdown"</a><br />
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Rotation to a windows-up attitude was delayed slightly because of the selection of a slow rotational rate by the crew. This delay resulted in the slight delay in LR acquisition, which took place prior to completion of the rotation.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPL9LT8hrO-pdXhWCIY2oNceaV56k4WeYVS8y6bMdH2ppGBbm9MEW8TTOaTJs7eTiUr9Nyx13c9Xz_aTDINawaznnjHrDvS7yw0k-KX5u_jP8sgliHvDPfm_c2ecLBX04gURFxVPS8hIPl/s1600/Automatic_Guidance.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="223" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPL9LT8hrO-pdXhWCIY2oNceaV56k4WeYVS8y6bMdH2ppGBbm9MEW8TTOaTJs7eTiUr9Nyx13c9Xz_aTDINawaznnjHrDvS7yw0k-KX5u_jP8sgliHvDPfm_c2ecLBX04gURFxVPS8hIPl/s400/Automatic_Guidance.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">LM Automaitc Guidance programs and landing phases. If not touched the computer would have run first P63 then P64 and finally P65 to put the LM on the Moon surface to a nominal point. Due to various errors in computer estimations the commander usually switched to the P66 mode and landed it semi automated.</span></i></span></td></tr>
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<br />
The approach phase was consistent with premission planning. The descent headed into the area near West Crater because of an initial navigation error, approximately 3 nautical miles down range.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis98rKP9UoAyvF-kpmZkHlI7TzpMUpjsXRbEQ1cewNkTgUPNZXBoRoJIrnC2_JoaMsaRSd4oY0vOpLXsfvVq7ZAeiVq3ufsGYs0F_jnbmXBYdoT7ueaPEI3Q0Q2nAinbSksL2R9iIav2ke/s1600/A11_LM_Final.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="396" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEis98rKP9UoAyvF-kpmZkHlI7TzpMUpjsXRbEQ1cewNkTgUPNZXBoRoJIrnC2_JoaMsaRSd4oY0vOpLXsfvVq7ZAeiVq3ufsGYs0F_jnbmXBYdoT7ueaPEI3Q0Q2nAinbSksL2R9iIav2ke/s400/A11_LM_Final.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo 11 LM's final landing point compared to the computer's target point and Armstrong's estimat about it.</span></i></span></td></tr>
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<br />
<i>[Armstrong - "My guess was that the outer northeast slope of West Crater was where the computer was taking us."]</i><br />
<br />
<i><i><i>[Fjeld - "</i>Post-mission analysis showed that the actual computer target is more
than 500 feet west/northwest of where Neil thinks the LM is taking
him."] </i></i><br />
<i><i> </i> </i><br />
During the approach phase, the LPD indicated to the commander that the automatic system was guiding to a landing up range of West Crater. Later on, the landing appeared to be heading into the rock field just beyond West Crater. This uncertainty was caused by several factors: the time rate of change in LPD angle, errors introduced by terrain variations (primarily slope), and the lack of time for visual assessment because of crew diversion to guidance-program alarms. (Refer to the section entitled "Real-Time Analysis"). Therefore, not until the beginning of the landing phase did the commander try to avoid the large area of rough terrain by assuming manual control (P66 guidance) (see previous parts af this article about the LM landing programs available) at an altitude of 410 feet (<i>550 ft</i>) when the forward velocity was only 50 fps. An LPD input was made, but in discussions with the crew, it was determined that this input was inadvertent.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO1qKVgYf_dyVmDRemheyd89Yg5-Dld9bJ4O5ePB2X6g0klngTJydLAJrdCBrA0QDcX2-xt64Fd-xH0wu3PgCJaY2z-wYML6DBvj3e9Wh_9-PfNpE5CFeZkQXKVo7CqvF2yevAMlhthc9-/s1600/ap11_lm_as11_40_5927.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjO1qKVgYf_dyVmDRemheyd89Yg5-Dld9bJ4O5ePB2X6g0klngTJydLAJrdCBrA0QDcX2-xt64Fd-xH0wu3PgCJaY2z-wYML6DBvj3e9Wh_9-PfNpE5CFeZkQXKVo7CqvF2yevAMlhthc9-/s400/ap11_lm_as11_40_5927.jpg" width="397" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="color: #cc0000;"><i><span style="font-size: small;">Apollo 11 Lunar Module seen from behind at its final landing spot</span></i></span></td></tr>
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<br />
The landing site is shown to have been moved, through manual maneuvering, approximately 1100 feet down range and 400 feet (<i>200 ft</i>) cross range from where the automatic guided descent (under P64 and P65 control) would have landed. The somewhat erratic behavior of the attitude and altitude-rate profiles can be best explained by Commander Neil A. Armstrong's comments to the Society of Experimental Test Pilots meeting in Los Angeles on September 26, 1969.<br />
<br />
"I [was] just absolutely adamant about my God-given right to be wishy-washy about where I was going to land."<br />
<br />
Touchdown have occurred 40 to 50 seconds prior to propellant depletion, only 20 to 30 seconds from the land-or-abort decision point and approximately 52 to 62 seconds longer than predicted for an automatic landing. The flying time below 500 feet was approximately 2 minutes 28 seconds.<br />
<br />
<span style="color: #274e13;"><i>[There seems to be some dispute about the last moments of the landing and how much the computer was right or wrong and if the Armstrong's correction was really required or not and how much did it change the final course. The landing was successful and that is the main important.]</i></span> <br />
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<br />
<b>Other Apollo Landings</b> <br />
<br />
Here are the videos about the other Apollo landings. They are very informative if you are familiar with the <span class="short_text" id="result_box" lang="en">special <span class="">vocabulary </span></span><span class="short_text" id="result_box" lang="en"><span class=""><span class="short_text" id="result_box" lang="en"><span class=""></span> <span class="">and</span> <span class="">abbreviations </span></span>used.</span></span><br />
<br />
<br />
YouTube video: <a href="https://youtu.be/kFSa6vUix70" target="_blank">"Apollo 12 landing from PDI to Touchdown"</a><br />
<br />
YouTube video: <a href="https://youtu.be/oZZe-xXx9_o" target="_blank">"Apollo 14 landing from PDI to Touchdown"</a><br />
<br />
YouTube video: <a href="https://youtu.be/AxqKlDsgMzc" target="_blank">"Apollo 15 landing from PDI to Touchdown"</a><br />
<br />
YouTube video: <a href="https://youtu.be/JSXhb3J05ps" target="_blank">"Apollo 16 landing from PDI to Touchdown"</a><br />
<br />
YouTube video: <a href="https://youtu.be/A7y5feeMvEo" target="_blank">"Apollo 17 landing from PDI to Touchdown"</a><br />
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Which landing was the best .. maybe you can decide?<br />
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<br />
<b>REFERENCES</b><br />
<br />
/1/<span class="Apple-tab-span" style="white-space: pre;"> </span>Apollo News Reference, 1968<br />
<br />
/4/<span class="Apple-tab-span" style="white-space: pre;"> </span>MECHANICAL DESIGN OF THE LUNAR MODULE DESCENT ENGINE<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Jack M. Cherne, Manager,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Engineering Design Department,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Power Systems Division, TRW Systems,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Redondo Beach, California, U.S.A.<br />
<br />
/5/<span class="Apple-tab-span" style="white-space: pre;"> </span>APOLLO EXPERIENCE REPORT - DESCENT PROPULSION SYSTEM,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>William R. Hammock, Jr.,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Eldon C. Currie, and<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Arlie E. Fisher,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Manned Spacecraft Center, Houston, Texas 77058<br />
<br />
/6/<span class="Apple-tab-span" style="white-space: pre;"> </span>APOLLO EXPERIENCE REPORT - MISSION PLANNING FOR LUNAR MODULE <span class="Apple-tab-span" style="white-space: pre;"></span>DESCENT AND ASCENT, Floyd V. Bennett, Manned Spacecraft Center<br />
<br />
/7/<span class="Apple-tab-span" style="white-space: pre;"> </span>LMA790-2 - Lunar Module Vehicle Familiarization Manual - Nov 1, 1969<br />
<br />
/8/<span class="Apple-tab-span" style="white-space: pre;"> </span>Don Eyles - Tales from the Lunar Module Guidance Computer, 2004<br />
<br />
/9/<span class="Apple-tab-span" style="white-space: pre;"> </span>YouTube videos:<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>"LM - Capcom" audio and<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>"LM - Flight Control" audio.<br />
<br />
/10/<span class="Apple-tab-span" style="white-space: pre;"> </span>NASA TN D-8227 -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>M. D. Holley, W. L. Swingle, S. L. Bachman,<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>C. J. LeBlanc, H. T. Howard, and H. M. Biggs -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>APOLLO EXPERIENCE REPORT - GUIDANCE AND CONTROL SYSTEMS:<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>NAVIGATION, AND CONTROL SYSTEM DEVELOPMENT PRIMARY<br />
GUIDANCE, May 1976<br />
<br />
/11/<span class="Apple-tab-span" style="white-space: pre;"> </span>NASA TN D-8086 -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>D. Harold Shelton -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>APOLLO EXPERIENCE REPORT - GUIDANCE AND CONTROL SYSTEMS -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>LUNAR MODULE STABILIZATION AND CONTROL SYSTEM, November 1975<br />
<br />
/12/<span class="Apple-tab-span" style="white-space: pre;"> </span>NASA TN D-7990 -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Kurten, P. M.:<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Apollo Experience Report - Guidance and Control Systems:<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>Lunar Module Abort Guidance System., 1975.<br />
<br />
/13/<span class="Apple-tab-span" style="white-space: pre;"> </span>NASA TN D-7289<span class="Apple-tab-span" style="white-space: pre;"> </span>Willium H. Peters, Kenneth J. Cox<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>APOLLO EXPERIENCE REPORT - GUIDANCE AND CONTROL SYSTEMS -<br />
<span class="Apple-tab-span" style="white-space: pre;"> </span>DIGITAL AUTOPILOT DESIGN DEVELOPMENT, June 1973<br />
<br />
/14/<span class="Apple-tab-span" style="white-space: pre;"> </span>Wikipedia<br />
<br />
/15/<span class="Apple-tab-span" style="white-space: pre;"> </span>Internet & Flicker<br />
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<br />Exo Cruiserhttp://www.blogger.com/profile/03559556533503422733noreply@blogger.com0