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

The space station mission was kind of the culmination of all of my experience of being a NASA Astronaut, so it had brought all of my previous experience into play. I had to learn the Russian language to a fluent level so that I could function as the co-pilot of the Soyuz Spacecraft that we flew up and back from the space station. And then the challenge of being the Commander of the whole expedition, a six and a-half month flight aboard the international space station. I felt the burden of the whole mission on my shoulders, which was fine, and fortunately everything did go well.

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.

Space is very unforgiving business

Richard Branson is probably the most visible of the private commercial space guys, and what is venture, Virgin Galactic is about is sub orbital flight. That is, you'll see a spacecraft that looks more or less like an airplane and it will fly into space, but only spend about 15 minutes. It'll go up in a parabolic arc and then fall back down, and so the customers on that flight will only get about five minutes of weightlessness. They'll get to glimpse the horizon of the Earth, take a look at it before just before they start coming back down into the atmosphere.

This was the first time we had two ex-Soviet Cosmonauts in Houston. A lot of us, including me, viewed it with some skepticism, because I grew up during the Cold War, so I had been hit with all this propaganda all along that their stuff wasn't that good, it wasn't that safe and we were so much better. What I found out later was that their space stuff was very good and good enough that I was certainly comfortable flying on their equipment. So, it was kind of a revelation of sorts as the years went by and I think it underscores the importance right now of international cooperation.

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.