In the beginning, space programs were engineering challenges, undertaken because somebody thought that there would be eventual benefits from exploring or colonizing space.

Then, it became a political competition: chiefly between the United States and the Soviet Union. The implied idea was that the country that could achieve the most in space exploration had the best political or economic system.

After that, space programs were justified by science for the sake of science: increasing knowledge, say, about the details of the chemistry of the Martian soil.

The political competition never was the right motive for a space program, of course. It led to Apollo missions that achieved nothing to smooth the way for further and more ambitious moon landings. The astronauts went, planted a flag, did some science, and left the moon no better prepared for future human occupation than it had been before they arrived. That's the essential problem with political motives: once the grand gesture is made, there's nothing more to be done.

Today, and for the past decade, the space program has been doing science. Unfortunately, it's been doing science with the same lack of regard for bootstrapping future human enterprise in space that held sway when the motive was primarily political.

Space programs should not be primarily about science. Science should be carried out, of course, but the primary emphasis of space travel should be industrial. Industry is interested not in going once, whether to grandstand or to carry out a few experiments, but in going to make the going easier later, so that profits can be made.

American capitalism has never ventured into space for the usual reason that capitalism doesn't really work like Ayn Rand said it would: the human lifespan is short, compared to the march of events in history. The generation of original investors would not live to see the payoff, and, being selfish individualists, they're not racially motivated enough to be content that their grandchildren would be greatly enriched by their sacrifices.

So the bootstrapping process never took place. We're still, industrially speaking, at "square one," as we have always been, where space is concerned. We've been exploring space without any intention of having it ever become self-sustaining or fruitful.

What have we really done in space? We've learned much, but in terms of building infrastructure beyond Earth orbit we have done nothing.

The incorrectness of our reason for space exploration will either remedied soon, or it never will be remedied at all. The world has only a few more decades in which to build an off-planet industrial basis. After that, we will lack the physical prerequisites for leaving this planet because those necessities will have been consumed by our wars, our cars and our air conditioners.