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.|
The total amount of mass reserved for the EV and the RV is 150 000 lbs each or 300 000 lbs together. They are almost identical, only different due to the difference of the route selected for inbound and outbound routes. The allowed dry weights can be calculated using the rocket equation calculators and the fact that about 4 km/s is required for bot directions. If less delta-V would be required for the actual time of the mission then that could be translated for more material on board and vice versa.
- EV/RV full weight 150 000 lbs
- dry weight 40 000 lbs
- specific impulse 311 s'
- --> delta-V = 4.03 km/s
|The Apollo CSM Command/Service Module is same as the LEAMOR SM and Orion capsule. The size is different due to the different propellant amounts etc.|
We know that the weight of the Orion return capsule, which should be carried during both parts of the mission due to abort options to the Earth, is about 20 tons. So the dry weight of the service module (SM) could be 10 tons and the habitat module (HM) 10 tons also. It could also be for example 14 tons for the SM and 6 tons for the HM. The exact figures depend of how everything required is divided between the different modules. This is just some kind of a raw estimate at this point.
- Capsule 20 tons (lbs)
- Habitat Module (HM) 8 tons
- Service Module (SM) 12 tons (+ propellants 110 tons)
- All together dry 40 tons (lbs), full 150 tons
Both EV and RV would have the same figures.
The habitat module could be as follows:
There are some private bed rooms for each of the three astronauts. The sports room serves also as the airlock and inside it is also the small centrifuge which job is to keep the astronauts fit for the Mars ground mission and back to the Earth. During the use of the centrifuge the attitude gyros must be switched to some other mode since most likely the huge centrifuge would make them inoperative.
Would be nice to see some centrifuge tests in the ISS also sometimes? There was a plan to send one to the ISS but it was dismissed, maybe due to the attitude problems? The following picture shows some idea of a small human centrifuge but it is very preliminary and not tested. The advantage of such a unit would be the possibility to use it for high gravity rates (more than 1 g) in order to promote the bone growth etc.'
The Earth re-entry capsule (Orion) can take 6 astronauts but for 3 astronauts it can carry more consumables etc. The following picture illustrates the re-entry capsule.
|The re-entry capsule (Orion)|
An additional safety factor might be to send both the EV and RV close to each other both during the outbound and inbound missions to the Mars. In case of any problems they might dock to each other and the crew could switch the vehicles if required. Both can do the re-entry to the earth since they have both the capsule included.
/4/ Apollo archives
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