What’s more feasible: to build a self-sustaining colony on Mars or as a self-sustaining space station? The 1976-book The High Frontier advocates the latter while Elon Musk seems pretty confident that Mars is the better option. Why? Are they taking other factors into account? Me, I’m not asking where it would be nicer to have a station but where it’s easier to get it done.
Things in favour of a station on Mars:
- You already have some gravity.
- Less radiation (0.7 vs 1.8 mSv/day)
- Some sort of raw materials on your front door
- Lots of space to put stuffs without it floating away.
Things in favour of a space station, say a design similar to an updated O'Neil cylinder like the Kalpana One (or is there something more up-to-date?) in GEO or near-earth space:
- Closer to Earth. I guess if you want to reach Mars within closer to three than the full six months, you’d need a lot more propellant than to get to the space station. (I can find many different Delta-V estimates, probably depending on lots of parameters like how much you aerobrake and what constellation the planets are in. And yes, I'm aware that Delta-V to dollars is exponential.)
- Little Delta-V needed to get to and fro asteroids, which should make it easier to mine them. You can then cherry-pick (to a certain extent) raw materials from asteroids.
- A lot more solar power (no atmosphere, no sandstorms, no/less night)
- Some processes are probably actually easier in 0g.
- Seems like no heating needed (or is that a minus because it’s hard to get rid of the excess heat?)
Any more factors? How would you weigh them in terms of feasibility?
Edit: More objectively, what do experts think and how do they reach that conclusion? Has our knowledge/assumptions changed between O'Neill's and Musk's approaches or do they just have different opinions?
Edit2: With "self-sustaining" I mean able to sustain itself without major imports of materials from earth which would make the endeavour at current launching costs very expensive. Importing small masses of specialised equipment (like computers and instruments) from earth is allowed, as well as obviously whatever you need to get it all going. More importantly, regularly importing raw materials from asteroids (and/or the Martian surface for the Martian colony) is allowed—for the purpose of this question, I consider those facilities part of the colony.