Having walked on the Moon, I know something about what we need to explore, really explore, in space.

My family has always supported my activities, whether it was doing combat in Korea, flying progressively and challenging fighter-jet aircraft in Europe, or studying for a doctor's degree at MIT. They have been always very supportive and understanding of the challenges and risks involved in my career. A family needs to work as a team, supporting each other's individual aims and aspirations.

Mars has a bit of air pressure; maybe we can build up that atmosphere to be a bit more accommodating to humans.

The view from space is like having a globe on your desk -- it's a broadening experience.

When we set out to land people on the surface of Mars, I think we should as a nation, as a world, commit ourselves to supporting a growing settlement and colonization there. To visit a few times and then withdraw would be an unforgivable waste of resources.

The best way to study Mars is with two hands, eyes and ears of a geologist, first at a moon orbiting Mars... and then on the surface.

You can never tell when a commercial space venture will suddenly become viable.