President Bush’s recent announcement of a plan to send astronauts to the moon, Mars and beyond, to “see and examine and touch for ourselves” the worlds outside our own, has fired the imaginations of millions of Americans in a way that recalls the space passion created by President Kennedy’s planetary vision of the 1960s.

But if you think Bush’s bold initiatives for manned space exploration are a dream come true for astronomers, science’s most starry-eyed lot, you’d be mistaken. Or so says Neil Comins, a professor of physics and astronomy at the University of Maine and a prolific author of books and articles on the cosmos.

“Let’s first look at the positives of sending humans to Mars,” says Comins, who then pauses several empty seconds for effect. “OK, now let’s look at the negatives. There is no scientific benefit at this point. There is no engineering benefit. There is no economic benefit and there is no social benefit.”

In other words, he says, manned missions to Mars within the next 10 or 15 years is such a half-baked plan that Bush’s only conceivable purpose in hatching it is to help get himself re-elected.

“And that’s not news,” Comins says, referring to polls suggesting that about half the population regards the president’s plan as politically transparent and an astronomical waste of tax money that should be used for greater social benefit.

But Comins says it is not only the extraordinary expense of the plan – estimated at half a trillion dollars, conservatively – that he and most of his fellow astronomers find impossible to justify.

“We have no idea yet what the surface of Mars is like, so we have no idea what risks astronauts would face as we try to get them there alive and back again,” says Comins, who, coincidentally, is working on his eighth astronomy book, to be called “A Tourist’s Guide to the Hazards of Space Travel.”

Unsuspecting astronauts, he argues, could encounter large amounts of ozone upon their arrival, or dangerous amounts of hydrogen peroxide locked into the surface rock.

“If we don’t plan for such things, they could have a devastating affect on the human beings we send,” he says. “We can see the volcanic activity on Io, Jupiter’s moon, but we don’t know if there is similar volcanic activity on Mars. If there is, an astronaut could be in serious danger of being buried.”

Unknown biological materials also could pose a threat, not only to the astronauts who uncover them but to Earth itself once the exotic and largely unanalyzed life forms are brought home.

How much radiation will the astronauts encounter from the Sun, he asks, or from cosmic rays and magnetic fields en route? The Japanese Nozomi Mars mission spacecraft, which was due to arrive on the red planet last December, was crippled instead when it was zapped by a massive solar flare in part of its orbit.

“Had humans been aboard that spacecraft, they’d be dead,” Comins says. “We simply do not know enough about how to protect humans during those flights, and the effect on humans is the crucial part. We don’t yet have a way of landing people on Mars comfortably – the technology is not there. Nor do we know how to get them back off the planet again. If the return ship developed problems, there is no service station on Mars to help. It truly could be a technological nightmare, from start to finish.”

The more prudent scientific course, he insists, is to continue gathering valuable information from nonhuman space explorers – the orbiters, Mars rovers and wondrous space telescopes – that will help remove some of the unknown factors that right now could imperil human life.

“We should send out large numbers of unmanned spacecraft to survey the risks and the dangers,” says Comins. “Rather than abandon the Hubble telescope, which is still showing us amazing things, we should be investing in it, as well as the Chandra X-ray and the infrared telescope. If we abandon those things to help fund manned missions, as has been proposed, we’ll have thrown away billions of dollars and get nothing out of it but the likelihood of dead astronauts.”

Sending people to Mars without a compelling reason would be nothing more than a financially wasteful and unnecessarily risky adventure, he says. But sending people when a reason has been found – one with commercial appeal, such as the discovery of valuable minerals with Earthly benefits – would lure private enterprise into the act and ease the burden on taxpayers.

“That might be a reason to colonize, and I’d be all for it,” Comins says. “I think we should send out 50 more rovers to Mars, to passing comets and nearby asteroids, and to the moon. Because right now we don’t even know what’s out there and whether we need it. The unknowns absolutely justify our continued exploration, but that does not justify our sending people at this point. We are just not ready to undertake those risks.”