| > As far as I can tell, humans can't survive for extended periods of time in gravity as low as it is on Mars. Our only datapoints for long-term human activity are "Earth gravity" and "complete freefall". This is one of the things I hope we can answer in the near-term with manned lunar missions. > Given that we can't figure out how to build subterranean cities at scale on earth We know perfectly well how to build subterranean cities at scale on Earth. We don't, because it's expensive and because people tend to like having windows for natural light and fresh air. It'd be cheaper on a smaller planet like Mars (less gravity to fight against), and it ain't like there'd be a possibility of natural light or fresh air anyway given the radiation and unbreathable atmosphere. > Honestly, a self sustaining space station seems easier to achieve than a self sustaining Mars base You'd have the same radiation problem if not worse (and no "underground" to shield you from it; "park it behind a celestial body" doesn't really work, either, when you have cosmic rays coming from all directions - said cosmic rays being the dominant form of space radiation), but other than that, yes, space stations are more practical - and you can build 'em anywhere, not just Mars. You could also build such a spinning structure on an airless body like the Moon or Ceres. Ceres is in fact pretty close to ideal as far as human colonization goes: low gravity (so it's easy to build there and easy to leave for other destinations), close proximity to the rest of the asteroid belt (so lots of opportunities for space mining), and it's pretty much a giant ball of water ice and hydrocarbons so we'd have everything we need (at least on a fundamental chemical level) for air, food, and water alike. |