I didn't really decide that I wanted to be an astronaut for sure until the end of college.

The view of earth is spectacular from space. Most people imagine that when astronauts look out the window of the shuttle they see the whole earth like that big blue marble that was made famous by the flights that went to the moon. But the shuttle is much, much closer than those astronauts were. So we don't see the whole planet, the whole ball at once, we just see parts of it.

Studying whether there's life on Mars or studying how the universe began, there's something magical about pushing back the frontiers of knowledge. That's something that is almost part of being human, and I'm certain that will continue.

Some astronauts sleep in sort of beds - compartments that you can open up and crawl into and then close up, almost like a little bedroom.

My background is in physics, so I was the mission specialist, who is sort of like the flight engineer on an airplane.

When you're getting ready to launch into space, you're sitting on a big explosion waiting to happen.

So most astronauts getting ready to lift off are excited and very anxious and worried about that explosion - because if something goes wrong in the first seconds of launch, there's not very much you can do.