For an election-year president, the temptation to announce new forays into outer space is close to irresistible. It is a chance to distract Americans from mundane earthly realities like unemployment, rising budget deficits and the death toll in Iraq. It is a chance to lure voters in key aerospace states like California. It is a chance to make a little history, as John F. Kennedy did when he pledged to put a man on the moon. And it is a chance to make a ringing speech about the spirit of discovery.
When George W. Bush announced on Wednesday that the U.S. would send men back to the moon and eventually to Mars, he evoked Meriwether Lewis and William Clark, those great explorers of the American wilderness. Like them, "we have undertaken space travel because the desire to explore and understand is part of our character," Mr. Bush said.
But it was more than just a questing spirit that motivated Lewis and Clark and the other greater explorers of our world. Captain Lewis set out to find a land route to the Pacific Ocean because president Thomas Jefferson asked him to in hopes of opening up North America to colonization and economic exploitation. Columbus discovered America by accident as he sought a shortcut to the Indies, source of spices and other luxuries coveted by the European elite. Magellan set out on his voyage around the globe for essentially the same reason. Each one made the voyage because he thought he might find something useful.
Of what possible use to humanity are the moon and Mars? Both are barren, lifeless places, with conditions utterly inhospitable to human habitation. The latest pictures from the robotic Spirit rover, spectacular as they are, show a desolate, rocky desert. Even if science could find ways of protecting human settlements from the radiation, the extreme cold and the lack of breathable air, it is hard to imagine why people would want to settle there. To mine for minerals? How would they be transported back to Earth? To ease world population pressures? How do we get millions of people to Mars?
Some say we should go to Mars for science. But the science, so far, seems pretty uninteresting. Apart from examining rocks, the main scientific purpose of the rover missions is to determine whether the arid planet might once have been wet enough to support some form of life -- not, mind you, whether it supports life now (highly unlikely), but whether it might have at some distant time in the past. Is answering that question worth the $400-billion (U.S.) that the experts say it would cost to send a manned expedition (and that was NASA's estimate in 1989, when George Bush Sr. proposed it)?
If the question is really important, it can be answered far more cheaply by robots like Spirit, a marvellous little machine that doesn't care about the lack of air or the fierce temperatures. Supported by an army of scientists, navigators and computer technicians back at NASA, the Spirit and its twin, Opportunity (scheduled to land on Jan. 24), can do just about everything a man in a space suit can do at a fraction of the cost. The Spirit-Opportunity double mission will cost $820-million, a bargain-basement price by space-exploration standards.
As Mr. Bush himself put it this week, "The environment of space is hostile to human beings." In a manned space expedition, most of the enormous cost goes to keeping the fragile human cargo alive. Unlike hardy robots, the astronauts must have air, food, warmth and, of course, a way to get home. One of the main barriers to a manned Mars mission is finding a way to supply enough fuel to power the rockets that would boost the returning astronauts out of Mars's gravitational pull, far more powerful than the moon's. The robots will just stay happily behind.
Of course, putting a robot on Mars isn't nearly as exciting as putting a human being there. As Mr. Bush put it, "We need to see and examine and touch for ourselves." NASA applauded Mr. Bush's announcement because it knows that manned flight thrills the public and shakes money loose from Congress.
Space enthusiasts say the ultimate value of manned exploration is to expand humanity's presence beyond the known world, "to boldly go where no man has gone before," as they say on Star Trek. But to justify the enormous cost and the considerable danger, there must be some benefit beyond the delight of seeing a human footprint in the Martian dust -- some practical benefit to the well-being of humankind. Four hundred billion dollars to handle a Martian rock "for ourselves" is pretty steep. So let the rovers do the rock watching, and the humans stay home.
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