How has life as an astronaut changed your perspective about life on Earth?
It's made me quite optimistic. The Earth has sustained life for billions of years; it's an extremely resilient system, beautiful and immense. It's great to be able to see the world that way. You just don't see local problems but global, millennial solutions that have endured. It also very much decreased my sense of "them." Everyone has a sense of "us" [versus] "them," and where you draw the line kind of depends on who you are. It might be your town, your state, your country, your religion, whatever. I have been around the world about 2,500 times and traveled extensively on the surface of the Earth. To me, the sense of "them" has faded into a distance.