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

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.

There are parts of the Earth that are covered with pollution all the time. I saw weather that was unexpected. Storms bigger than we've seen in the past. This is a human effect. This is not a natural phenomenon.

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.

On this flight, my fourth spaceflight, I also became the record holder for total days in space and single longest mission.

I personally think going to Mars, if it takes two years or two and a half years, that's doable. Certainly, the first people who go there, that's going to be a big motivator, being first getting to Mars.

We have a lot of systems here on board the space station, and we can't call a repair man when one of them breaks.

My career with the Navy and NASA gave me an incredible chance to showcase public service to which I am dedicated, and what we can accomplish on the big challenges of our day.

There are few aspects of everyday life that aren't touched by the technologies developed for space travel.

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.

When you look at the... atmosphere on the limb of the Earth, I wouldn't say it looks unhealthy, but it definitely looks very, very fragile and just kind of like this thin film, so it looks like something that we definitely need to take care of.

It's for us to take care of the air we breathe and the water we drink. And I do believe we have an impact on that, and we do have the ability to change it if we make the decision to.

The workouts have positively impacted the astronauts' bones and muscles, and they are coming back in really good shape. But some are losing bone and muscle but not as much as we saw in the early days.

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.

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 think a good life-work balance is important, and that's even more important in some cases on the space station.

Space has its own unique smell. So whenever a vehicle docks, or if guys are out doing a spacewalk, the smell of space when you open up the hatch is very distinct. It's kind of like a burning-metal smell, if you can imagine what that would smell like.

The earth is a beautiful planet.

There are definitely parts of Asia, Central America that when you look at them from space, you're always looking through a haze of pollution. As far as the atmosphere is concerned, and being able to see the surface, you know, I would say definitely those areas that I mentioned look kind of sick.

A lot of the data we collect is stuff that has to be analyzed on the ground. For instance, we can't see, you know, bone loss. Our cells, you know, that's something that we'll have to notice with imaging technology when I get back.

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.

I believe in the importance of flying in space and the research that we do.

If you go on a journey to Mars and get into deep space, there is several hundred times, maybe 300 times the radiation.

As far as whether there is life there on Mars or whether there was actually ever life there, I don't know. It would be great to find out, though.

The thing I like most about flying in space is not the view. The thing I like about it is doing something I feel very, very strongly about.

When we do things that are really hard, we can achieve great things - and that has worked as a great model for me.

We've got to get rid of the stuff on the space station somehow. So we do have a pretty significant capability to bring back stuff on SpaceX that you might not imagine.

I've flown in space four times now, so it's going to be hard in that respect, but I certainly look forward to going back to Earth. I've been up here for a really long time and sometimes, when I think about it, I feel like I've lived my whole life up here.

The majority of astronauts have to change their eyeglasses while in space. They bring eyeglasses with them and typically change a few months into the mission.

I don't mean to say it's not fresh on the space station, but there's nothing like new, cold air coming into the capsule.

I feel more like an environmentalist since I've been up here. There are parts of the Earth that are covered with pollution all the time. I saw weather that was unexpected. Storms bigger than we've seen in the past. This is a human effect. This is not a natural phenomenon.