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

I think I need to continue to think and plan and marry all of the different things that we could do that make transportation in space from the earth to the space station, from the earth to the moon to space stations around the moon to visiting an asteroid.

The purpose of going to Mars is for humans to first begin to occupy, permanently, another planet in the solar system. The astronauts or pilgrims, whatever you might call them, are going to be very historically unique human beings.

I want to keep on the move, keep stimulated and challenged.

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

Everyone who's been in space would, I'm sure, welcome the opportunity for a return to the exhilarating experiences there.

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