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.

When I was a little kid, we only knew about our nine planets. Since then, we've downgraded Pluto but have discovered that other solar systems and stars are common. So life is probably quite prevalent.

The biggest benefit of Apollo was the inspiration it gave to a growing generation to get into science and aerospace.

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 feel we need to remind the world about the Apollo missions and that we can still do impossible things.

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.

I'm convinced that sending people to Mars is so expensive that if you go once and bring the people back and then go again and bring the people back, we're eventually going to run out of money. But what if we send people the first time and they don't come back? What if they stay there?