Now you're coming back to Earth, and things are getting more and more dynamic.

Now, I've never flown in space; but the folks who have say that on landing day, you know, you've just spent maybe a week and a half, sometimes two weeks in orbit and you're used to the things happening slowly in space.

There's been a tremendous amount of work that's been done that you can't see in Columbia.

Well, for me it really wasn't a case of deciding to be an astronaut.

So, we have to get up and get pumped up for each day.

And then, when I thought about joining the Air Force, flying seemed like a natural extension of the motorcycling experience. You're going faster, higher. You're operating a machine that's a lot more powerful than you are.

That's what Hubble can do for us. It can tell us whether the universe is expanding forever or if one day it's going to come back together.