Will we go explore? Absolutely. That's what humans have been doing since we left the caves in Ethiopia. Why? Because this is part of our nature. We're curious. We want to push the envelope. That will never stop. We will see people on Mars, hopefully in our lifetime. My hope is that the endeavour is so large, so complex, so technically challenging, so demanding and so uplifting, that it will be done with a consortium of nations. I hope the people who do set foot on Mars will do so for all mankind, and not just one nation in particular.

The one thing we can't really train for is weightlessness, real weightlessness. It's a ton of fun. It's pure Newtonian physics. You push in one direction, you go in the opposite direction with an equal force.

I am definitely a little more nervous for my colleagues when I'm working at mission control than I am myself, on the shuttle.

Almost everything I do when I approach an operational problem comes from the time I've been in space. It's a way of organizing your thoughts. We use problem-solving; what we call "what-if-ing." What if this happened? What would we do? We go over plan B, C, D, E, F, and whatever else, depending on the criticality of what we're doing. This kind of thing can be applied almost everywhere, even at home.

Definitely you don't become famous by doing something bad; that's a professional death sentence. You remember that whatever you do, someone will be watching, and you study all the time. It sounds terrible, but you get used to it. I'm 45, and I'm still at school, essentially.

You're always under the microscope, and you don't know which mission you're going to get. It's a surprise.

A lot of people, I think, would love to see the earth from above, wear a spacesuit. Certainly, when I was a kid, I wanted to wear a spacesuit.