There's a need for accepting responsibility - for a person's life and making choices that are not just ones for immediate short-term comfort. You need to make an investment, and the investment is in health and education.

Trips to Mars, the Moon, even orbit, will require that we provide astrotourists with as many comforts from home as possible, including paying each other.

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.

Let's not spend resources that we don't need to be sending astronauts back to the moon. Let's not spend expensive resources on bringing people who have reached Mars back again. Prepare them to become a growing colony.

Space tourism is a logical outgrowth of the adventure tourist market.

To send humans back to the moon would not be advancing. It would be more than 50 years after the first moon landing when we got there, and we'd probably be welcomed by the Chinese. But we should return to the moon without astronauts and build, with robots, an international lunar base, so that we know how to build a base on Mars robotically.

I really hate to be put in the position of trying to justify something, a decision that was made. I'm a military guy: when a decision is made, I go along with it, whatever the manufactured controversy and criticism.