One of the things, and the most exciting, actually definitely the most exciting thing is, having children. You know, I didn't have children before. I had been married only a year before my space station mission, so having three-year-olds is a whole new experience and that's the new adventure. It may sound funny because people have kids every day, but having your own kids, having my own kids, was as fundamentally, or maybe even more fundamentally life changing then even flying in space.

Qian Xuesen, the father of the Chinese Space Program, studied in the United States, and he was a protégé of Theodore Von Carmen's at Cal Tech and helped start the jet propulsion laboratory there, and then he got caught up in the anti-communism wave and was accused of being a spy and was actually deported back to China where he built from nothing, their entire missile and space program. So, in a way, in a very real way, the United States in trying to protect so-called protect our secrets and throwing this guy out of the country, we helped seed and start the Chinese missile program.

We were doing something called telemedicine, where we were using the ultrasound. One interesting application of this ultrasound is the possibility that you could possibly use it to measure critical bone areas during a long space mission and track if you're losing bone in these areas. On Earth, when they check you for bone loss, you get in this big machine. It's the size of a room and it's got a platform with an x-ray that scans your whole body and in critical areas and it takes a while and it just wouldn't be practical to have a machine like that in space.

The United States, Russia, and China are the only three countries in the world that can launch astronauts into space. Mostly in the U.S. you see some companies trying to launch private commercial people into space, but nobody's done it yet. The only private vehicle that's made it into space so far is Spaceship 1 in 2004, and that was an effort that was funded by one of the Microsoft founders, and he spent about $20 million to develop this spacecraft to do a sub-orbital flight. And it's not the same as going into orbit, but it was a huge first step.

My mistakes made were learning how to work with different groups of people. I mean, I went to school at Berkeley, which is a pretty diverse group, but working in a professional setting, I hadn't really done that before and learning about office politics, learning about interactions between different people and I made a lot of mistakes there during my time as a young person. I was 19 or 20 at the time. So, I would say those were my biggest career mistakes, but fortunately they were made in the context of an engineering co-op program and not in a professional field.

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

When Russians were having troubles, the Space Shuttle supported the Space Station Mir bringing up much needed supplies and replacements, critical spares, really. That they were able to keep their space station going for much longer than they would have without us. So, I think that shows the value of international cooperation.