It was designed to have an impact on the stalemate over Mutually Assured Destruction with the Soviet Union. Us reaching the moon convinced Gorbachev and other leaders that the Soviet Union couldn't compete with the U.S., so they revised their agenda. But people have short memories.

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.

History gets reinterpreted as time goes on. Many times, the participants are lost in the retelling of the story.

The energy varies with the square of the velocity, so if you need five times the velocity, that's 25 times the energy.

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

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.

I think the public needs to be reminded just how much inspiration and intention was given throughout the world to be bold, to send human beings to the moon in the '60s and the '70s. It's important now to bring together the nations that weren't able to do it then and help them do it. We need to move forward.