The great question is how to survive with other people in such a closed space for a long time and stay psychologically stable. We need science to dig into that, and to really to do more with how we evolve, grow up and deal with our internal issues.
I bet first expeditions to Mars are foinf to give a mass of new data on how that affects the human psyche.

Imagine how it's changing your paradigm - instead of living, say, in Wisconsin, you shift towards the Solar system...
That's boring, I guess, and it's all been described a hundred times, but here it is - for real!