I don't think we're going to build a 50-person spacecraft or a 100-person spacecraft.

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.

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

I think there would be no shortage of applicants to the government astronaut corps to be settlers on the planet Mars. And I think this would be very inspiring.

I think both the space shuttle program and the International Space Station program have not really lived up to their expectations.

We must still think of ourselves as pioneers to understand the importance of space.