20 March 2008
Visiting the moon is one thing. It’s a difficult, complicated, dangerous, and exciting thing. But it’s also a thing that we have done before. Sending people to Mars is a whole new ballgame. Instead of a few days of travel, future Mars astronauts will likely be looking at a six month trip there, and at least as long to get back, with an extended stay on Mars in the middle. And of course, there’s the whole problem of landing safely and then launching back out of Mars’ gravity well with enough speed to get all the way back to Earth.
These complications have led some to consider an intermediate step between sending astronauts to the Moon and sending them to Mars: send people to the moons of Mars, Phobos and Deimos. Last week at LPSC, I spoke to Sanjaykumar Vasadia about his poster proposing exactly that.
The idea behind a mission to Phobos and/or Deimos is that they are easier to get to than the surface of Mars because they are quite small, so landing on them would be more like docking with them. We could send people to one of Mars’ moons to gain experience in a long-duration mission without the risky landing at the end. Also, since Phobos and Deimos are probably captured asteroids, we could learn a lot about asteroids in the process. Finally, the real heart of Vasadia’s poster was that there are resources on Phobos and Deimos that can be used in space exploration.
Asteroids are well known for having lots of free metals: instead of iron ore, many asteroids simply have lumps of metallic iron and nickel in them. Also, Vasadia argued that there may be a significant amount of water in Phobos or Deimos. I had never heard of this, and when I pressed him on it, he said that their low density must be due to the presence of ice inside them. I am pretty skeptical about this: there is a evidence that many asteroids are not very dense, but that it is simply due to the fact that they are “rubble piles” rather than single monolithic rocks. Still, if we assume for the moment that Phobos or Deimos do have significant amounts of water, that would be great news for space exploration. Some of the best rocket fuel can be made by simply splitting water into its components: hydrogen and oxygen.
Vasadia envisions a solar-powered mining station on Phobos and Deimos that can generate valuable metal resources to send back to earth or down to the Martian surface. The station would also serve as a spaceport and refueling station for missions coming back from and going to the Martian surface.
It sounds like science fiction, and much of it probably is, but the idea of in-situ resource utilization, or “living off the land” will be vital for successful human missions. In spite of some problems with the proposal discussed here, I think that a human mission to Phobos or Deimos is a great idea. It makes sense scientifically to study Mars’ moons, and it provides a valuable intermediate step between landing on Earth’s Moon and landing on Mars.