I know what you're saying, Rob. What's the commercial impetus for putting people on Mars, or even the moon? I don't have the imagination to answer that. I don't know if space tourism can take us that far. Does anyone want to spend their vacation in a tin can, even if the can is on the surface of the moon?

But Apollo proved at least two things about government-funded space programs: they can succeed spectacularly (that is, when they're not failing spectacularly), and they can evaporate like a drop of water on a hot skittle when politicians decide they've got no more to gain by continuing to hurl people into space.

If private industry can find profit in astronautics, then it'll probably persist as long as it produces a good bottom line. And entrepreneurs are creative...once a company has a presense in space, it'll look for new ways to make it worth their while. So the business reasons for putting people into space are likely to become more numerous over time.

Just thinking out loud. (Perhaps "thinking" is too grand a word...)