I think if you time it right getting from Mars to Earth actually isn't so bad since Earth is in a lower solar orbit than Mars. Think of it as a big de-orbit bur

I think if you time it right getting from Mars to Earth actually isn't so bad since Earth is in a lower solar orbit than Mars. Think of it as a big de-orbit burn. Of course you'd want it to deposit you into Earth-orbit (perhaps after some aerobraking), hence the need for proper timing, but on the whole much easier than trying to enter the higher orbit of Mars. Two rocket scientists I asked confirm this, but asked me not to quote them on it, so I'm paraphrasing :). Also, Mars' lower gravity makes achieving escape velocity substantially easier than on Earth. Of course, it's still a not insubstantial amount of fuel, but it's not quite as bad as duplicating the trip up to get back. Personally, though, if we shipped up enough stuff to survive, I'd be cool with a one-way trip.