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.

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.

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.

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.

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.

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.

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.