Just that it hasn't justified the billions we've poured into the space program. I consider myself a fairly scientifically literate person but I couldn't come up with one space-station originated industrial process or product without looking in a NASA website. Pure science is something else, look how much astronomers have learned from Hubble. But I can't think of one new product or service that its led to.

Don't get me wrong, going into space is a great enterprise, and it has incalculable value for humanity, I'm all for it, it's just that from a purely cost-accounting point of view, from a pure applied research standpoint, we would have been better spending that money on earth.

Space HAS paid for itself, the communications satellites have been an extremely profitable technology that have changed our world. So have been the earth-resources and navigation satellites. And of course, we all know about Tang, that delicious and nutritious breakfast drink! Much of our computer tech comes from space (and the military) but all that money was spent right here on the ground. Basic research advances science, and some of it will eventually pay off handsomely way down the line, in ways we can't possibly anticipate.

I'm just saying that much of what we have been promised never quite materialized. Its like those nature shows we watch on public TV that tell us about fascinating research conducted on tropical rain forest fungi, or deep sea smoker vent ecosystems. There is always a somber scientist justifying the work by mentioning some Brazilian mushroom or abyssal sulfur-eating plankton that has shown promise in cancer research.

In the 19th century, paleontologists and geologists were telling us the world was millions of years old, but astronomers and chemists could not explain how the sun could shine for more than a few thousand years without using up its chemical fuel reserves. This, of course, led to the discovery of radioactivity, fission and fusion, and nuclear physics.

Those rock hounds and star gazers stumbled on one of the great secrets of matter, it led to Quantum physics. a totally new source of energy, but they had no way of knowing they would do so, or even understanding what they had found. It was totally unexpected. What we get out of the space program will be like that. Totally unexpected, and way down the line.

We do science because its fun. That's all the justification we need. The benefits to humanity will come much later, probably when we least expect it.