Since the Columbia accident, the Russian space agency, or the Russian space program, has been literally carrying the load bringing us all the supplies we need on the Progress vehicle, smaller amounts on the Soyuz vehicles.

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.

We would like to carry out 100 percent, or maybe more, of our scientific program; I would like to devote some of my spare time toward extra scientific work.

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.

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.

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.

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