 And though it does solve some of the problems, it really doesn't solve them all. And so it's been recognized that a trip to Mars, a year in weightlessness, is going to be difficult to achieve because when someone arrives at Mars, it's going to be difficult for them to stand on their own. When astronauts come back from a six-month mission, they are put in a chair, and it's difficult for them to walk normally for a significant period of time. So how do you do it on Mars where there's no landing crew to help you?