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.

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.

Of course, you'll have to meet the physical and psychological demands. A space walk takes a lot of energy.

I remember getting advice like, "Oh, do what interests you. Don't worry about tomorrow, live for today," kind of thing. And to a degree, you've got to do that, you've got to follow your passions. You've got to follow your dreams, but you also have to have a plan. You can't just say I'm going to do what interests me today and I'm not going to worry about tomorrow, that doesn't work. And anyone who's tried that I think quickly finds that out. Think about what turns you on, what do you dream about? But along with that, make a plan and work hard to make it happen.

What keeps me up at night? Probably most, thinking about the future for my kids. It sounds kind of funny, but not so much what they're going to do, but how as a parent, how my wife and I as parents, how best we should prepare them for the world. And I know everybody does this, I think everybody stays up at night thinking about the best thing for their kids, and astronauts are no different.

The Americans are still the leaders in human space flight. I feel we have a danger here of kind of stagnating. We're kind of resting on our laurels and there's a danger going forward if we don't take bold steps to really support human space flight in this country that we could fall behind. After the space shuttle is retired, we're going to have a big gap, five to seven years, at least where we're not going to have the ability to send our own astronauts into space, we'll have to buy rides on the Russian Soyuz, and so that will be a pretty big step down for us.

As commander I was responsible for the overall success of the mission, and so I had to know at least a little bit about everything.