dietz@SLB-DOLL.CSNET (Paul Dietz) (12/09/85)
I just saw a book that pretends to be an official manual for astronauts participating in a mid-1990's UN Mars mission. Ballantine books is the publisher, I think. It's a big red paperback, costs $12.95 + tax. The book describes in detail an 11-man mission to Mars. The craft is powered by uprated space shuttle engines, burning LH/LOX. The crew lives in zero gee, and stays at Mars for 30 days. I didn't see a mention of cost; something like 40-50 shuttle flights (or the equivalent) are needed to lift the vehicle, crew, various satellites and fuel into orbit, so launch costs alone are around $6-10 billion. Some comments: (1) most of the shuttle flights are for bringing up fuel and fuel tanks. Why not reuse shuttle external tanks? Carrying fuel is what they're designed for, after all. (2) It's clear that the major cost of the mission is launching material from the ground. (3) If the astronauts stay in Mars orbit then there is little technology needed for a Mars mission that has not already been developed or will be developed for other uses (the space station, for example). A good first mission would have the astronauts rendevous with Phobos and/or Deimos, and explore the Martian surface with remote controlled drone aircraft and rovers. (4) Once we have a space station and cheap (x 10 cheaper) launchers, a Mars mission becomes quite inexpensive (~ a billion dollars?). (5) The technology needed for a Mars mission is also useful for near-earth asteroid missions; indeed, the latter may be easier and could serve as a useful first step. Samples can be recovered from small asteroids much more easily than from Mars. (6) Since the Mars vehicle uses LH/LOX propellant, most of the fuel mass is liquid oxygen. Studies have shown that even at moderate production levels (100's of tonnes/year?) lunar production of LOX can be competitive with LOX launched from earth. An aside: the vehicle must carry shielding against radiation from solar flares. In a solar flare, do the energetic protons hit the spacecraft mainly from the direction of the sun, or do magnetic fields make them come from the sides as well?