The neatest thing about research and science is we don't necessarily know what's going to come down the pike. We think we know what we're working on. Oftentimes, discoveries are made when you're trying to discover something else. You end up accidentally discovering a different thing. So, one of those things might happen that enable us to have more efficient rockets.

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.

As far as Russia goes, they've been our partner for a long time now, since the early '90's. So you know, what's that, that's more than 15 years. And there have been times where things were a little tense, a little testy, but by and large, the partnership has been very successful. To give you two examples of that, when the Columbia accident occurred, the Russians supported us with their spacecraft faring our astronauts, including me, to the space station and also supplies.

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

You saw Britain back in the early days of sailing ships. They were the sea power, the controlled the seas and they had colonies all over the world and then you can look at history and watch the way that their empire kind of crumbled. I certainly don't want that to happen to the United States in space technology.

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 thing that you worry about your first flight or any flight is some kind of a problem coming up that is going to keep you from doing it. Whether it's being hit by a car, or getting in a bad accident, or coming down with some other medical disqualification. But once the boosters light, you're going.