I'm 45, and I'm still at school, essentially. Even after being assigned to the mission, I had to write a number of exams, with people commenting on my performance.

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 science behind Interstellar is interesting, because some of it is absolutely real astrophysics and orbital mechanics, some of it is theoretical physics, and some of it is completely Hollywood. When a science fiction movie is based on plausible science, it's really good.

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

Some people will always be volunteers to explore, and it is, in my mind, a privilege.

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.

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