"I know enough about the moon to know how unpleasant and inhospitable it is. . . . I know enough about Mars to know that you can't live there, you can't settle it. Mars and the moon are two ugly islands. So then, you say, what's the point of going to them? The point is to be able to say I've been there, I've set foot on them, and I can go further to look for beautiful islands."