Our three big emergencies are fire, loss of pressurization or contaminated atmosphere. Any of those things in a spaceship are very deadly and time critical. Everybody's trained, but I'm the commander of the ship, and it's up to me to decide.
When you're on one of the Caribbean islands, sometimes it's hard to picture how they fit in with the rest, but when you see them all joined together like a necklace from space, you see the natural geographic connectedness of them all.
Now, as an astronaut, I have to bring a Sharpie with me everywhere - so I have a pen to sign autographs.
You can get claustrophobia and agoraphobia - a fear of wide, open spaces - simultaneously on a spacewalk.
Our role is to develop techniques that allow us to provide emergency life-saving procedures to injured patients in an extreme, remote environment without the presence of a physician.
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 International Space Station is a phenomenal laboratory, an unparalleled test bed for new invention and discovery. Yet I often thought, while silently gazing out the window at Earth, that the actual legacy of humanity's attempts to step into space will be a better understanding of our current planet and how to take care of it.
To be one of the world's top space robotic arm operators is a necessary skill for an astronaut, but it doesn't have much carry-over.
Ever since I was nine years old and I watched Neil and Buzz walk on the moon, I have felt passionately that this is an interesting human adventure. This is one of the things we're doing that is really fundamentally important, as we leave our home planet, but also exciting.
I'm a mechanical engineer, and I grew up on a farm, so I like practical hardware - somebody's elegant solution that proves itself over the long term.
Airline food is cooked in an oven and then kept warm. Space station food is often cooked in an oven and then thermo-stabilised, irradiated or dehydrated and then stored for a year or two before you even get to it.
What I like to do when I get to a new place is buy local music early on and listen to it while we're driving around. I think it helps explain and illuminate the culture of where you are if local music is playing.
You should have a fear of some things. That doesn't mean it incapacitates you from your ability to figure out a way to deal with it.
The beauty of the space station, and of human spaceflight, is that it is now at a level of maturity where you can invite people on-board, which is what I worked so hard to do on social media and all the videos I made.
I once made myself black out by pulling G too quickly while flying an F-18. Being unconscious in a single-seat airplane is not good. Fortunately, I woke up in time. I learned how to better plug-in my anti-G suit.
I'm really looking forward to it, if you can imagine floating weightless, watching the world pour by through the big bay window of the space station playing a guitar; just a tremendous place to think about where we are in history.
I've had a chance to see something that is way outside everybody else's frame of reference and gives a perspective that is very different from everyone else's.
Nothing focuses your mind quite like flying a jet. That's one reason NASA requires that astronauts fly T-38s: it forces us to concentrate and prioritize in some of the same ways we need to in a rocket ship.
Just taking risks for risk's sake, that doesn't do it for me. I'm willing to take risks that I think are worth it, and I've worked so hard to make sure that I survive.
One place that I looked at a lot from space and which looks alluring is New Zealand, especially the North Island. It's a big broad valley with a river flowing through it, and you can see the wine-making dryness of the land.
