There's a tremendously satisfying freedom associated with weightlessness. It's challenging in the absence of traction or leverage, and it requires thoughtful readjustment. I found the experience of weightlessness to be one of the most fun and enjoyable, challenging and rewarding, experiences of spaceflight. Returning to Earth brings with it a great sense of heaviness, and a need for careful movement. In some ways it's not too different from returning from a rocking ocean ship.

The feeling of reduced gravity and the limitations of the space suit resulted in a slow-motion movement. Perhaps not too far from a trampoline, but without the springiness and instability.

Look at what Silicon Valley has done - the advance of computers.

Do we really need these big, gigantic, heavy rockets? What if we launch a rocket that's empty, and its sole purpose is to act as a source of fuel on the Moon? Who should build that? Well, I think the U.S. should build that.

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

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

It's real easy to manufacture what you think the people want to hear. But that's not very honest.