Apollo On-board Guidance History (Part 16, Apollo Control Systems)

[This article is based mainly on D.G. Hoag's paper about Apollo's on-board Guidance, Navigation, and Control System history /10/]

APOLLO ON-BOARD GN(et)CS HISTORY /10/

"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.

The Beginnings /10/

"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 Instrumentation Laboratory at MIT under a contract with the Air Force Ballistic Missile Division.

Milton Trageser (left), Hal Laning and Richard Battin

DSKY Hardware (Part 15, Apollo Control Systems)

[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.

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.

The AGC (and DSKY) was designed at the MIT Instrumentation Laboratory under Charles Stark Draper, with hardware design led by Eldon C. Hall. Early architectural work came from J.H. Laning Jr., Albert Hopkins, Richard Battin, Ramon Alonso, and Hugh Blair-Smith. The flight hardware was fabricated by Raytheon, whose Herb Thaler was also on the architectural team.

Eldon C. Hall

Most of these people can be seen in the following film

YouTube video: "Computer for Apollo, MIT Science Reporter Film"]

Mars Atmosphere and Water

There 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.

Figure 1. Water Phase Diagram

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.

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.

Figure 2. Water Phase Diagram on Earth and Mars

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.

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.

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 Mount Everest for example.

["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"]


VIDEOS

YouTube video: "Water Boiling at Room Temperatures, Under a Vacuum"

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Apollo 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).

DSKY Interface (Part 13, Apollo Control Systems)

(DSKY I/O Interface, Apollo Guidance Computer)

[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/.]

Figure 1. DSKY (Apollo Guidance Computer Display and Keyboard)

(Mars) Vehicle "2500" - Part 2 - The Plans

Basically 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.

Here is the more detailed general plan of the vehicle "2500".

Figure 1. General purpose lander for Mars, Moons, etc.

Mars Vehicle "2500" - Part 1 - Basics

This Mars Vehicle (MV), model "2500" is part of the LEAMOR (Light Extended Apollo Mars Orbit Rendezvous) total mission plan. See the article for general ideas about that Mars mission plan.

Figure 1. Mars Vehicle (MV) "2500" with ablative lower part and heat shield above ablative fuel balls.

Command Module ECS (Part 12, Apollo Control Systems)

Environmental Control System (ECS)

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.)

Apollo CM Environmental Control Unit (ECU), a major part of the ECS

[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.]

CM 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.

Command Module CM with the Service Module SM connected together with an umbilical (right).  

Standard Spacecraft Docking Port (IDSS)

If you are going to build the latest and greatest spacecraft you might want to have a standard docking port in it .. so that it could dock with all possible space stations and crafts. Looks like NASA and other national organizations have joined their efforts and created a new standard called "International Docking System Standard" (IDSS). It is available for anybody to be downloaded in this link.

Picture of the IDSS International Docking System Standard docking port

Here is a YouTube video about the principle of the docking port.

MECHANICAL DOCKING

The docking connects two identical rings together. So all IDSS ports can dock with each other (there are no male or female versions, etc.). Here is a general view of the docking.

Standard Spacecraft Docking Port (IDSS) Principle

The maximum ball that can be fed through the port is 800 mm diameter .. the outer ring diameter is 1200 mm. It has 3 guide petals which latch with the capture ring. In each petal there is a mechanical latch which will lock with the latch striker in the capture ring automatically. The 3 petals interleave with their counter part petals. All together 6 latches will lock in the soft capture system (SCS). Here is a general view of the port.

IDSS Standard Docking Port

The docking happens in several phases;

1. Soft Capture
2. Hard Capture
3. Electrical Connection

The soft capture system (SCS) makes the initial mechanical connection with soft forces to be later connected harder with the hard capture system.

The Hard Capture System (HCS) performs the final structural mating between the two
vehicles, establishing a connection capable of withstanding atmospheric pressure
combined with the loads from planned mated operations of the two spacecraft. The hard capture is based on pins and hooks.

The final IDSS docking is based on hooks.

There are active and passive hooks in each slot. The active hooks will pull the passive hooks.

ELECTRICAL CONNECTOR

Additional to the mechanical docking the standard also defines an electrical connector. The electrical connectors are to be connected after the full mechanical docking is done with some mechanisms. Here is a picture of the electrical connector.

IDSS Electrical Connector pin layout

For additional details consult the IDSS standard.

RESOURCES

/1/ International Docking Standard

/2/ NASA Docking System

/3/ International Docking System Standard

/4/ Androgynous Peripheral Attach System

/5/ International Berthing and Docking Mechanism

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Soviet Options (1989) for a Manned Mars Landing Mission

This article is a direct reprint of the now unclassified historic article from the CIA WWW library /1/ -- originally printed in 1989. It has lot of interesting details about the Soviet Manned Mars program until 1989. Most likely today the Russian manned Mars mission idea and all over the world is largely similar.

CIA Library (not public)

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European Service Module (ESM) for Orion Capsule in Production

Airbus Defense and Space (DS) is building the new service module (ESM) for NASA (2015). The structural test version is to be delivered in this month. It looks very much the same as the 1960's version SM which was described in more detail in this article. We all remember the Apollo 13 mishap so lets hope they get everything right with all the numerous pressurized tanks.

The European Service Module made by Airbus DS

SM Service Module (Part 10, Apollo Control Systems)

Apollo Service Module (SM) was an important part of the Apollo Command/Service Module (CSM). Nowadays also the new SM which is connected to the Orion capsule is called a service module. Actually Europeans are just now building one (2015).


HISTORY /1/

North American Aviation logo

Apollo Command / Service Module was built by North American Aviation.

James Howard "Dutch" Kindelberger

James Howard "Dutch" Kindelberger was an American aviation pioneer, a leader of North American Aviation in 1934-60.

LEAMOR Mars Mission - Entry and Return Vehicles (Part 4)

PART 4: Entry and Return Vehicles

Why to have separated Entry and Return Vehicles (EV and RV) for the mission. Basically separating them makes it possible to divide the required consumables and propellants to two smaller amounts. And the one without the astronauts could then be sent using lower speed and less propellant expensive routes. Additionally two return capable vehicles in the LMO add to the safety of the astronauts. If one of the vehicles is broken the other one hopefully still is usable.

Return or Entry Vehicle without the Habitat Module (HM). Service Module (SM) to the left and the Orion re-entry capsule to the right.

LEAMOR Manned Space Craft - Modular Transport Engine (Part 3)

PART 3: Modular Transport Engine (TE)

LEAMOR stabnds for Light Extended Apollo Mars Orbit Rendezvous.

As we already have figured out that the large spacecraft must be modular (since the lift vehicle can only lift a certain amount to the LEO at one time). See the previous part of this article series and we call these about 150 ton (lbs) building blocks as L-modules.

L-Modules about 150 000 lbs each, size about D5 x L11.75

LEAMOR Manned Mars Mission - Why Modular? (Part 2)

PART 2: Why the Manned Mars Mission Must be Modular?

Simply because the launch vehicle can only lift a certain amount at any time - and that size or mass will be the maximum module size - and the only way to get larger masses and structures is to bolt them together in the low Earth's orbit (LEO).

LEAMOR stabnds for Light Extended Apollo Mars Orbit Rendezvous.

SLS can lift about 150 .. 300 tons (lbs) to LEO

LEAMOR Mission - Light Extended Apollo Mars Orbit Rendezvous (Part 1)

PART 1: LEAMOR MISSION BASICS

How to land a man on the Mars and return him safely to the Earth

It looks like the main problem is NOT that we couldn't do it but that we maybe need more time and/or money for it?

I represent here a simple LEAMOR mission plan to Mars and back which just extends the Apollo missions and tries not to do anything more in the first phase than just to get a man on the Mars and return him safely to the Earth. LEAMOR stands for Light Extended Apollo Mars Orbit Rendezvous. (See also LOR).

The following picture shows the basic Mars mission phases.

Typical Mars mission and its main events.

520 Day Mars Mission Simulation by ESA Yields OK

THE SHORT AND LONG STAY MARS BASIC MISSION TYPES

As you already might know there are basically two types of low energy trips to Mars:: the Short Stay Mission (SSM) and the Long Stay Mission (LSM).

Long-Stay Mission (LSM)

NASA's Orion Capsule Development & Testing Video

Orion capsule after its first real re-entry (EF-1 Dec. 5, 2014) heatshield removed

 
There is a 1 ½ hour video in Youtube which I have to link here since it contains collected material of Orion capsule's development and testing. I would call Orion just a (re-entry) capsule since a spacecraft is a much larger set and requires the propulsion to get it anywhere at all. Sure if just the gravity assisted space travel was applied .. one might go very far only with the capsule alone but to be more comfort with it there should be some kind of a propulsion reserve to make at least the final burn back to the Earth.

Youtube video: "NASA's Orion Spacecraft Development & Testing (1080p)"

Here is the Orion's first used heatshield going to inspections.

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The Fastest Comfort Travel in Space (by Dr. Michael Minovitch)

Dr. Michael Minovitch introduces in the following video the idea of a very fast and comfort ride everywhere in space. The spacecraft either accelerates or decelerates during the whole journey using 1 G which is natural and most comfort for human. The trajectories are straight lines between any points .. no orbits used. The idea needs of course very powerful fuel and proper fusion engine. But since the fusion is possible .. it most likely will also be available in some scale for humans in the future.

Here is the video:

Youtube video: "11.0 Ground-To-Orbit Fusion Propulsion System for Achieving Commercial Interplanetary Space Travel"

Additional videos:

Youtube: "Magnetoplasma Rocket Engine (Ad Astra) (VASIMR)"

Youtube: "ISS Update: VASIMR Plasma Rocket"

Youtube: "Nuclear Propulsion in Space (1968)"

Youtube: "Ion Propulsion - Deep Space One (Documentary)(Part 1 of 4)"

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