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.

The prerequisite that people have a scientific or engineering degree or a medical degree limits the number of female astronauts. Right now, still, we have about 20 per cent of people who have that prerequisite who are female. So hey, girls: Embrace the very fun career of science and technology. Look at computer science. That's what I did.

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.

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

My husband and I don't worry about each other the way we might if we didn't have similar jobs. I sometimes get an email where he tells me he's heading off on a mission to do terrain avoidance 50 feet above the ground at 500 knots. And I just say, "Okay, have a good flight."

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.