When you’re flying to the moon, is there space for your mind to drift?

I remember my mind drifting for the first time on the eighth day of flight. We were getting close to home, and I started thinking about seeing my kids. I immediately had to stop that and say, “Nope, you do not have space for that in your brain.” The first five days—I wish Victor, Christina, and Jeremy were sitting right here, they would all agree—we were waking up and working until bed. And we were usually getting to bed about an hour later than we had hoped.

When you’re in that tiny spacecraft with four people, you’re all over each other. I feel like I’m close to you right now, but three weeks ago, I would have asked why we’re so far away. Everything that is easy becomes hard. Just making lunch: How do four people all make their food? If one person is exercising, nothing else can happen in the cabin. All that stuff was taking far, far longer than we had anticipated. We got much better as we went.

You mentioned putting Earth aside and focussing on the mission, but what does that mean when you’re on such a novel and extraordinary voyage?

Daydreaming is important. It’s important to be bored as a human. But, sometimes, you’ve got to remain caged. Instead of thinking about being home, hugging my kids, it would have been a lot better for me to think about, What’s breakfast tomorrow? Or: What are my crewmates doing and how can I help them? Maintaining an appropriate level of engagement with the spacecraft, with the control team, and with your crewmates. You never know what that spacecraft is going to throw at you.

We had a full-on fire emergency on our next-to-last day in space. It was a false alarm, but that stopped everything: all the electrical power, all the ventilation. We were just sitting there with an emergency tone going off with a completely stagnant spacecraft—no airflow, and it was heating up. You’re human, so there are moments of terror. We had quite a few orbital-trajectory-correction burns. Before each of them, save two, we had some sort of alarm go off, and I could feel my heart rate elevating. I could feel my adrenaline picking up. As long as you understand these emotions, I think they help you perform. Those bring you up to your A game. You see it in professional athletes.

What we do in the astronaut office is, I would almost say, scaring ourselves. We fly airplanes, we fly helicopters, we mountain-climb, we dive to the bottom of the ocean, we live underwater. All those things just get you much more comfortable being uncomfortable. When we had that fire emergency—which is the only emergency we ever had—everybody went straight to their jobs. We started knocking out all the procedures to make sure the vehicle was safe, and we were safe. It’s pretty cool to see that. Nobody was distracted. Everybody did exactly what we had trained to do.