[adrianN]

I don't think (mostly) self sustaining outposts on the Moon and Mars are technologically infeasible. See for example the studies Robert Zubrin did for NASA.

Whether there are sufficient economic incentives to actually build them is unfortunately a different question.

[dennisgorelik]

It's technologically feasible to send a mission to Mars.

It's unfeasible to have self-sustaining colony on Mars.

Mars Direct proposal does not even try to cover self-sustaining part.

[adrianN]

Actually it does, at least as outlined in his book.