When I saw the Earth from above, personally, as a spacecraft operator, it certainly reinforced and drove home the fact that there's one place where we can live right now. The seven billion of us are sharing a wonderful planet, and it's an absolute privilege to see it from above.

If anything, when you're up in space and you're inside a space ship, which is your home, and without which you would not survive, you know that Earth is your home. This is the only place you can return. In fact we're very meticulous. Part of our job is to maintain the spaceship. If we apply the same kind of model to Earth maybe we'd have a different outlook.

When you're a little different than others, it takes a little more time to fit in. If you really want to be there, there are no ingredients you need other than effort, perseverance and teamwork.

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'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.

Most astronauts are very down-to-earth people. Many of us, three-quarters, have an engineering degree, and we have a very Cartesian, rational approach to things. You don't go and get swept off your feet. That's not your job and that's not why you're hired. So if you get so mesmerized that you forget to do what you're supposed to do, whether it's to open the cargo door of the space shuttle or configure something inside, then you should not be there as a professional operator.

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.