"One of the things we have to do while we're on our spacewalks is loosen a lot of bolts. And that's complicated in space because you have to react to all the torques. That's the technical way to put it, but if you've ever been in a swimming pool and worked on something, you know that if you turn something one way, it's going to turn you the other. If you're on ice and you push on something, you obviously go the other way, and in space, of course, that's true in all three dimensions.
"So if you have an electric drill as we did, and loosen a bolt, and you're not tied down with your feet or your hands, you can feel it trying to turn you the other way. So we have to react to all the torques ourselves, and there are two ways to do it: one with your feet in a foot restraint, or free-floating."