As we begin to have landings on the moon, we can alternate those with vertical launch of similar crew modules on similar launch vehicles for vertical-launch tourism in space, if you want to call it that adventure travel.

Mars has a bit of air pressure; maybe we can build up that atmosphere to be a bit more accommodating to humans.

The decision to go to the moon is now appreciated and associated with President Kennedy's speech, but somebody else had told him it was a good idea. It turned out to be a good commitment, but it was a unique situation.

The universe is the way it is. It's not going to be changed by supplications.

Heavy lifting doesn't need to be heavy spending if we do the job right.

Space architectures capable of supporting a permanent human presence on Mars are extraordinarily complex, with many different interdependent systems.

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.