SYNOPSIS: Argues that space travel should be unmanned until much better technological advances come along

Some commentators have suggested that the Columbia disaster is more than a setback — that it marks the end of the whole space shuttle program. Let's hope they're right.

I say this with regret. Like millions of other Americans, I dream of a day when humanity expands beyond Earth, and I'm still a sucker for well-told space travel stories — I was furious when Fox canceled "Firefly." I also understand that many people feel we shouldn't retreat in the face of adversity. But the shuttle program didn't suddenly go wrong last weekend; in terms of its original mission, it was a failure from the get-go. Indeed, manned space flight in general has turned out to be a bust.

The key word here is "manned." Space flight has been a huge boon to mankind. It has advanced the cause of science: for example, cosmology, and with it our understanding of basic physics, has made huge strides through space-based observation. Space flight has also done a lot to improve life here on Earth, as space-based systems help us track storms, communicate with one another, even find out where we are. This column traveled 45,000 miles on its way to The New York Times: I access the Internet via satellite.

Yet almost all the payoff from space travel, scientific and practical, has come from unmanned vehicles and satellites. Yes, astronauts fitted the Hubble telescope with new eyeglasses; but that aside, we have basically sent people into space to show that we can. In the 1960's, manned space travel was an extension of the cold war. After the Soviet Union dropped out of the space race, we stopped visiting the moon. But why do we still send people into orbit?

In space, you see, people are a nuisance. They're heavy; they need to breathe; trickiest of all, as we have so tragically learned, they need to get back to Earth.

One result is that manned space travel is extremely expensive. The space shuttle was supposed to bring those costs down, by making the vehicles reusable — hence the deliberately unglamorous name, suggesting a utilitarian bus that takes astronauts back and forth. But the shuttle never delivered significant cost savings — nor could it really have been expected to. Manned space travel will remain prohibitively expensive until there is a breakthrough in propulsion — until chemical rockets are replaced with something better.

And even then, will there be any reason to send people, rather than our ever more sophisticated machines, into space?

I had an epiphany a few months ago while reading George Dyson's "Project Orion," which tells the true story of America's efforts to build a nuclear-powered spacecraft. The project was eventually canceled, in part because the proposed propulsion system — a series of small nuclear explosions — would have run afoul of the test-ban treaty. But if the project had proceeded, manned spacecraft might have visited much of the solar system by now.

Faced with the thought that manned space travel — the real thing, not the show NASA puts on to keep the public entertained — could already have happened if history had played out a bit differently, I was forced to confront my youthful dreams of space flight with the question, So what? I found myself trying to think of wonderful things people might have done in space these past 30 years — and came up blank. Scientific observation? Machines can do that. Mining the asteroids? A dubious idea — but even if it makes sense, machines can do that too. (A parallel: Remember all those predictions of undersea cities? Sure enough, we now extract lots of valuable resources from the ocean floor — but nobody wants to live there, or even visit in person.)

The sad truth is that for many years NASA has struggled to invent reasons to put people into space — sort of the way the Bush administration struggles to invent reasons to . . . but let's not get into that today. It's an open secret that the only real purpose of the International Space Station is to give us a reason to keep flying space shuttles.

Does that mean people should never again go into space? Of course not. Technology marches on: someday we will have a cost-effective way to get people into orbit and back again. At that point it will be worth rethinking the uses of space. I'm not giving up on the dream of space colonization. But our current approach — using hugely expensive rockets to launch a handful of people into space, where they have nothing much to do — is a dead end.

Originally published in The New York Times, 2.4.03