This is a really big space station. We do a lot of various kinds of work here, different kinds of science experiments; we have over 400 different experiments going on at any one time in different areas, from basic science research to medical technology, that hopefully will benefit more people on Earth.

It's a combination of science, maintenance, and general housekeeping. And then, occasionally, robotics activities or a spacewalk you might get to do.

There's a lot of work to do - not only the science but maintaining the facilities up here. When you go down from a crew of six to a crew of three, obviously you've lost half of your crew time available, so it does have an impact. But it's an impact we plan for.

I went to the University of Maryland for a year and was considering maybe, you know, being a medical doctor but decided my other interest was maybe flying airplanes in the Navy and just kind of changed my mind and changed schools and changed majors and decided to focus a hundred percent on that.

What we look for are people that are technically competent. You need a background in a scientific field, whether it's as a scientist, an engineer, medical doctor, or, you know, a person that's in the military with some kind of technical background.

People do really well on space missions, but it's the physiological, the medical stuff, the stuff like radiation, loss of bone mass and muscle mass and density. It's those things that we need to figure out.

It's an international space station. We have crew members from both the U.S. and Russia and now the United Kingdom with Tim Peake from the U.K... It's great to see that, on this space station, that we can work across cultures in a very cooperative way.

Just like the bones and muscles, the heart is designed to work in one gravity here on Earth, so when you put the heart in space, it operates differently and changes shape.

This year-in-space mission was a profound challenge for all involved, and it gave me a unique perspective and a lot of time to reflect on what my next step should be on our continued journey to help further our capabilities in space and on Earth.

When I look at the clouds over the Earth, and I know how high clouds are, I get a sense we are really, really far above those clouds. I wouldn't call it scary, but I am aware I am in space.

We don't do laundry because that requires a lot of water, and water's at a premium up here. Plus, it'd be pretty complicated, I think, to make a space washer, although I guess you could do it.

I don't think people have an appreciation for the work that it takes to pull these missions off, like humans living on the space station continuously for 15 years. It is a huge army of hard-working people to make it happen.

The Earth is a beautiful planet. The space station is a great vantage point to observe it and share our planet in pictures. It makes you more of an environmentalist.

The ride to orbit was impressive, as it always is. But once I got on board the space station, it really felt like I was visiting an old home; it felt very comfortable.

Your arms don't hang by your side in space like they do on Earth because there is no gravity. It feels awkward to have them floating in front of me.

Sleeping here is harder here in space than on a bed because the sleep position here is the same position throughout the day. You don't ever get that sense of gratifying relaxation here that you do on Earth after a long day at work.

I believe in exploration, and I will miss being on the front lines of that endeavor. On one hand, I look forward to going home, but it's something that's been a big part of my life, and I'm going to miss it.