In the space shuttle program, where we had males and females, I can tell you that nobody was doing that [sex] because there's absolutely no privacy. The only privacy would have been in the air lock, but everybody would know what you were doing. You're not out there doing a spacewalk. There's no reason to be in there.

In weightlessness, one of the physiological changes is a fluid shift. Your blood and fluid is equally distributed in your body. So that makes your calves and thighs and waist skinnier, and it makes your chest and women's breasts broader. The downside is your face is kind of puffy

NASA's training philosophy is "no surprises." So what they did is put a simulator on Earth where it looks exactly the same as a shuttle toilet and they put a camera down in the bottom of the opening for solid-waste collection, with a light that basically illuminates your asshole.

There's no way you can use water to collect waste in zero gravity. So, basically, our toilet on shuttle operations is a vacuum cleaner. The urinal looks like a Shop-Vac hose. It has different-shaped fronts on it for males and females to use. The urine is sucked down that hose and goes into a tank.

If you look at astronauts closely, their eyes look kind of puffy. And it gives you this mild headache. But one of the advantages of that, if you will.

The solid waste is returned to Earth with the shuttle. If we [astronauts] ever dump solid waste overboard, it's going to give new meaning to wishing upon a falling star.

And you're headed to a place with no bath and no shower. So you can just imagine how crazy it is to get up there, take your diaper off, have a urine-soaked crotch, and all you can do is wet a washcloth and wipe your skin off. You also have to do it on landing and spacewalks, too. It's not a ride that makes you springtime fresh.