Globalisation means many other countries are asserting themselves and trying to take over leadership. Please don't ask Americans to let others assume the leadership of human exploration. We can do wonderful science on the Moon, and wonderful commercial things. Then we can pack up and move on to Mars.

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

There are always door openings. And gradually, it accumulates. The opportunities open up in front of you.

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 wrote 'Reaching for the Moon' because I wanted to tell kids that all of us have a moon, a dream, that we can strive for. Even if you don't attain it, you can at least reach for it.

Astronauts are not superhuman. They lead ordinary lives and have varied personalities.

Being first outside the spacecraft would bring much more responsibility, and I really wasn't looking for that.