Because I was a tennis player, Billie Jean King was a hero of mine.

Eventually private enterprise will be able to send people into orbit, but I suspect initially it's going to have to be with NASA's help. Whether it's going to be a consortium or one entity remains to be seen. I could be wrong. I could be one of the old fogies! Rocket science is tough, and rockets have a way of failing. It happens. A company has to be willing to bear the risk of its rocket failing. It's a very large capital investment.

Science is fun. Science is curiosity. We all have natural curiosity. Science is a process of investigating. It's posing questions and coming up with a method. It's delving in.

On both of my flights, everything went very well.

The most important steps that I followed were studying math and science in school. I was always interested in physics and astronomy and chemistry and I continued to study those subjects through high school and college on into graduate school. That's what prepared me for being an astronaut; it actually gave me the qualifications to be selected to be an astronaut.

I do a lot of running and hiking, and I also collect stamps - space stamps and Olympics stamps.

If they asked me if I wanted to go into space tomorrow, I'd do it in a heartbeat. On the other hand, if they asked me if I wanted to go into training for three years and then go into space again, I'd probably say no.