Walking around on the moon was significantly easier than we'd thought it would be. There weren't any balance problems, so you weren't tumbling over.

In Mars, we've been given a wonderful set of moons where we can send continuous numbers of people.

We can continue to try and clean up the gutters all over the world and spend all of our resources looking at just the dirty spots and trying to make them clean. Or we can lift our eyes up and look into the skies and move forward in an evolutionary way.

I do celebrity ski races all over the world.

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 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.

The society of life on Mars, or the challenge of making Mars more livable, will have significant benefits on our attempts to modify and change in some ways the environment here on Earth.