Bill Tarver: It's that long space mission we're working towards, and we're selecting everyone to that standard because any one of them could be whom the Office wants on that mission. And when you go on these missions, you can't have medical issues. There are a few reasons for that. A simple one is, where are you going to store your pills? Also, pills are only good for one year based on what's called good pharmaceutical practice. If you go to Mars, how are we going to give you drugs that are good for three years? So we're very strict at selection. There are several common conditions that most people would think of as benign, but when we throw in long-duration and a long ways from home, those little things are magnified. Like if you're on a blood pressure medication, for example.