After assembly complete, when we have a larger crew on orbit, a more complex vehicle, more laboratories and more robot arms, maybe we'll have room for specialists. But right now we don't.

I think it's going to be a very important, unique data set in terms of measuring the behavior of your lower body in space and trying to figure out what we can do to preserve bone and muscle density.

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.

A civilization that only looks inward will stagnate. We have to keep looking outward; we have to keep finding new avenues for human endeavor and human expression.

If I wasn't doing this kind of exploration, I'd like to be doing some other kind of exploration. It might be more risky, or less risky, but, in the business of exploration, risk is part of the territory.

We're going to be focusing our science on things that will take us farther and longer into space. For many of those experiments, the crew members are human guinea pigs, which is fine; that's part of my job. I don't mind being a human guinea pig.

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