Mass Determination

Although a precise determination of masses is impossible at this point when many design decisions have yet to be made, references of similar mission designs can be used in order to estimate probable masses and thus choose the propulsive system.

The NASA/Boeing 90 day study produced a similar design consisting of a crew cab vehicle and a lander/ascender to transport a crew of four and then rendezvous in Martian orbit. The estimated masses from that study are :

Crew Habitat Mass 29 tons
Consumables Mass   8 tons
Lander            25 tons
Ascender Mass      7 tons

(Strategies For Mars : A guide to human exploration, Chapter 9, Mars Mission Designs : comparing the near term options, by Malcolm A. Le Compte and Julie P. Stets.)

The available propellants have the following specific impulses :

H2/O2 (chemical) 475 sec
CH4/O2 (ISMU) 370 sec
NTP                     900 sec

The other possible propulsive methods that are likely to be available in the future (though not immediately) are :