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.

Going to Mars would evolve humankind into a two-planet species.

I really hate to be put in the position of trying to justify something, a decision that was made. I'm a military guy: when a decision is made, I go along with it, whatever the manufactured controversy and criticism.

It's time to open the space frontier to citizen explorers.

Globalisation means many other countries are asserting themselves and trying to take over leadership. Please don't ask Americans to let others assume the leadership of human exploration. We can do wonderful science on the Moon, and wonderful commercial things. Then we can pack up and move on to Mars.

Neil Armstrong was the first man to walk on the moon. I am the first man to piss his pants on the moon.

The much-hyped Ares 1-X was much ado about nothing.