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

In a big picture sense, it's more national prestige that we're risking. You know, we are proud of our space program, but as we were talking earlier, the average American doesn't think that much about it right now. So, it may seem like something we could just give up and not really worry about it, but I think it starts creeping into the national psyche. If American astronauts have to hitch rides with the Russians or other nations in the future.

On the mission I brought a flag from China, I brought the stone sculpture from Hong Kong, and I brought a scroll from Taiwan. And what I wanted to do is, because as I was going up and I am this Chinese-American, I wanted to represent Chinese people from the major population centers around the world where there are a lot of Chinese people. And so, I wanted to bring something from each of those places and so it really wasn't a political thing and I hope people saw it that way. I was born here, I was raised in the U.S., and I'm an American first, but also very proud of my heritage.

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.

I actually had four space flights altogether, three times on shuttles. My second flight was really unique for me because I was going back into space, first of all. The first one was like an appetizer at a nice dinner. You know, you want to go up and you want more. So, the second time I got into space, it was neat because I got to actually do two space walks.

Two years ago, China tested an anti-satellite weapon that actually caused quite a bit of controversy and one of the controversies is that by blowing up a satellite, you are creating more space debris which is a hazard to satellites and spacecraft in lower Earth orbit and if they had been a partner, you'd have to do an experiment, and if they had been a partner in the international space station, would they have really done that test? They would have really thought twice about creating that tension between the countries and potentially endangering a project that they were a part of.

There is no one area of chemical engineering that specifically helped me in my career as an astronaut, it was more the general education in engineering. Also, it was a very difficult and rigorous course. So, it made me strong and resourceful.