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.

Coming down under a parachute is quite different as well. You hit the ground pretty hard, but all the systems work very well to keep it from hurting, so it doesn't even hurt when you hit. It was a great experience to be able to do both.

One day, people will be able to buy tickets to visit space.

The Russians right now require a customer coming in and spending about six months or so in Russia and they have to learn some Russian. They have to learn some critical words so they can, in an emergency, at least have minimum communication with the Russian commander of the Soyuz. They also have to learn systems and I think this just evolved that way. They just thought, what is the minimum set of things we think we can train someone to be more or less competent in our systems? And so that's what these guys go through. So, it's not just like buying a ticket and getting on an airliner.

I'm Chinese-American, of course, and so it's very interesting to see China actually launch their own astronauts, becoming the third nation, following the United States and Russia, to do so.

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

We were trying to do as much science as we could because that was the main purpose of the international space station. But without the shuttle to bring up heavy laboratory equipment and bring back samples, we were limited by what we could do, but I was proud that we actually accomplished more science that was planned for the flight. And I got a chance to do two Russian spacewalks on that flight, I had become an expert in U.S. spacewalks and using U.S. suits and techniques, and this was a chance to put on a Russian Orlan suit and do two construction space flights outside of the space station.