It was in the back of my mind, even while I was going to school, but it wasn't until I was at university studying engineering that I thought, well what do I really want to do? And I kind of came back to that and I said, well the degrees I'm trying to get are going to qualify me to apply. And so, that's what I did after I finished my, or after I was getting my doctorates. That's when I first applied to NASA.

Richard Branson is probably the most visible of the private commercial space guys, and what is venture, Virgin Galactic is about is sub orbital flight. That is, you'll see a spacecraft that looks more or less like an airplane and it will fly into space, but only spend about 15 minutes. It'll go up in a parabolic arc and then fall back down, and so the customers on that flight will only get about five minutes of weightlessness. They'll get to glimpse the horizon of the Earth, take a look at it before just before they start coming back down into the atmosphere.

In 2006, I became the fist American to be allowed to go visit their astronaut center in China in Beijing. I think that it makes sense for the U.S. to work with China in the future and I hope to see, if the political atmosphere between the United States and China allow for us to do more cooperation together, especially in the area of human space flight. I think in the same way that it's help improve the relations between the U.S. and Russia; it would help to improve the relations between the U.S. and China.

You saw Britain back in the early days of sailing ships. They were the sea power, the controlled the seas and they had colonies all over the world and then you can look at history and watch the way that their empire kind of crumbled. I certainly don't want that to happen to the United States in space technology.

One of the biggest concerns about going out beyond lower Earth orbit is the radiation. We find that exercise seems to counteract a lot of the negative effects of space flight, like bone loss and muscle atrophy and cardiovascular systems issues. We exercise two hours a day on the station, which is a huge hit out of your day. It's great for staying in shape, but you know, it cuts into the productivity of the crew and if you look at how expensive it is to get a crew into space, if we can keep them healthy and have them exercise, but spend less time doing it, we can get more done.

I had done everything I could do as an astronaut, and we have a long line of inexperienced astronauts waiting for their first missions, and so my role really should be to step aside and help them prepare for their missions, rather than to try to get another mission.

Even though I knew I was inside the space shuttle getting ready to go fly, something about it wasn't completely real up until we got the call at about one minute to go, to close and lock our visors and start our oxygen flow. People often ask me, "What did it feel like right at the moment of launch?" And they're surprised when I tell them actually what I felt was relief. It wasn't like being anxious or scared or anything. It was relief because this is something I had wanted to do my whole life and now that the boosters had lit, we were on our way to go do it and nothing was going to stop us.