Leaving the space station was bittersweet - I had been there for a long time and looked forward to leaving, but it is a remarkable place.

When I did my spacewalks, it was during space station construction. So the shuttle was docked to the fledgling ISS at the time. So we would always stay tethered.

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.

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.

A space station is a rangy monstrosity, a giant erector set built by a madman.

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.