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Monday, August 02, 2004
Skylab to Mars III

Mass break-down for our fictional Voyager to Mars...

  • CSM (fully fuelled) 30,329 kg (inc. 18,413 kg propellant)
  • Crew: 204 kg (3 @ 68 kg)
  • MEM: 24,947 kg
  • Multiple Docking Adapter: 6,260 kg
  • Airlock Module: 22,225 kg
  • Saturn Workshop: 35,380 kg
  • Instrument Unit: 2,065 kg
  • extra supplies (1,000 days @ 1.27 kg/day/person): 3,810 kg
    [the extra supplies are arranged in lockers that form a radiation storm shelter in the core of the Workshop]
  • Sum Total: 125,220 kg
  • Earth Return sub-total: 98,862 kg

    The CSM main engine puts out 9,979 kgf of thrust - 97.86 kN. As you can see the Earth Return stack masses just 98,862 kg - perhaps a couple of tons less once waste is dumped pre-orbital insertion. Hence it begins deccelerating at 1.01 m/s^2, burning its 18,413 kg of propellant which enables ~ 650 m/s dv. This is easily enough to park the Voyager in a Highly Elliptical Earth Orbit and let the CSM de-orbit. The re-entry speed is higher than an LEO return, but a bit lower than a Lunar mission return, hence it is easily handled by the CM's heat shields.

    But what will it be like for the crew? The gees can get quite high - will it be tolerable after months of zero-gee? In the novel, Voyage, NASA has already made several long duration missions to a Moon-Lab, which is Skylab in Lunar Orbit. Hence they have already tested astronauts at the expected gee-load. But I wonder, of course, if some sort of gees can't be supplied by rotating the Voyager...

    And tonight on Channel 10 News is a quite good article on the Mars Society's mission to Australia's Red Centre - not quite the Red Planet, but a very useful exercise. A real voyage to Mars will require a lot of parallel thinking to get carried off successfully - raw Space and Mars itself are alien, deadly environments that need our collective skills as a species to survive. Hence my analogy, parallel thinking by many minds to let those first pioneers have the best chance of survival.

    The elastic space-suit that got mentioned sounds really interesting - rather than gas pressure the idea is to supply counter-pressure for breathing via elastic force of the suit itself. This allows better freedom of movement and uses less air-supply to sustain. Also there can be no explosive decompression if there is a tear. Another technology they should be working on (and probably are) is rebreather oxygen supplies, which scrub expelled air of carbon dioxide and return it to the system, rather than directly venting like SCUBA systems. With such an astronaut could carry oxygen for a day easily, rather than mere hours.

    Mars also allows lighter meteroid protection. On the Moon micro-meteroids had to be dissipated by solid and padded protection in the suits, else the astronauts would be covered by bruises (or worse) fairly quickly. On Mars the atmosphere burns-up/deccelerates all those hyper-velocity pests, letting the far fewer larger meteorites through to dig those craters being explored by Spirit and Opportunity currently.


  • Posted at 12:18 am by Adam

     

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