Every day, we get a little bit closer to the kind of expertise and the kind of experience we're going to need to go there. I'd love to be the guy walking on Mars.

Even with only two people on board, where maintenance is a large piece of our working day, we still have time to do scientific research. We have to be ready to support those Shuttle visits in a lot of different ways.

It took me a long time to get selected as an astronaut. In fact, I applied for 20 years before I was selected.

Researchers can measure what kind of angles your legs take up during the day when they're just trailing around behind you in weightless conditions, and what kind of impacts you feel during your exercise. They're going to compare that with what we do on the ground.

It so happened that my goals kind of matched my career progression toward becoming an astronaut.

Small samples in the centrifuge will spin at varying rates to create synthetic gravity, like the gravity of Mars or the gravity of the moon, and measure how the specimens respond within the centrifuge.

There weren't any astronauts until I was about 10. Yuri Gagarin went into space right around my 10th birthday.