I believe that space travel will one day become as common as airline travel is today. I'm convinced, however, that the true future of space travel does not lie with government agencies -- NASA is still obsessed with the idea that the primary purpose of the space program is science -- but real progress will come from private companies competing to provide the ultimate adventure ride, and NASA will receive the trickle-down benefits.

I have no doubt that humans will go to Mars. And I feel that America has led so many things in space - we have invested so much, and we have a lot to gain - that America could and should be the nation that should lead the settlement of Mars.

You need propellants to accelerate toward Mars, then to decelerate at Mars, again to re-accelerate from Mars to Earth, and finally to decelerate back at Earth. Accordingly, the mass of these required propellants, in short, drives our need for innovative launch vehicles.

Pascal Lee is a true pioneer of Mars exploration.

I don't believe any pair of people had been more removed physically from the rest of the world than we were.

I was not the commander, I was a junior person, so once both were outside, I followed my leader, because we (NASA) had not put together detailed jobs of people outside. I believe it could have been improved. But it was very successful for what it was.

Russia perhaps is still entertaining the possibility that the moons of Mars might have access to ice or water.