Finding menacing asteroids is a first step

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GARDEN GROVE, Calif., Feb. 24 (UPI) -- A cadre of space scientists is becoming more adept at sorting out the swarm of asteroids and comets floating through the solar system and has turned its attention to the more-daunting job of doing something about the potentially disastrous collision with Earth.

Organizing a means of fending off an incoming rock several miles in diameter before it plows into the planet's surface will involve not only engineering a defense system that will be straight out of the science fiction genre, but also work in the more-mundane fields of basic astronomy, cost-benefit analysis and congressional lobbying.

"We know what we need to do, but we need the resources to do it," Don Yeomans of the Jet Propulsion Lab in Pasadena said at this week's Planetary Defense Conference in Southern California.

The conference organized by the Aerospace Corporation and the American Institute of Aeronautics and Astronautics brought together around 100 experts who have focused their cosmic knowledge and curiosity on the unthinkable possibility that mankind's long run on Earth could be abruptly ended by the same type of extraterrestrial impact that brought the age of the dinosaurs to a close.

"An asteroid impact with Earth is the only natural disaster that can literally destroy all of humanity," said Rusty Schweickart, a former astronaut and member of the committee that organized the conference in Garden Grove. "It is also the only natural disaster that can be prevented by humankind."

The potential for disaster is no secret. The energy packed into an asteroid no more than 16 meters in diameter is comparable to a nuclear bomb, and even smaller objects pack a punch as well.

Along with the prehistoric extinction of the dinosaurs, an air burst by an exploding asteroid has been blamed for the mysterious flattening of a 30-mile stand of timber in Siberia in 1908.

Retired Boeing engineer Robert Wood proposed at the conference that his review of 19th Century astronomical observations bolstered the theory that a white-hot comet broke up in the atmosphere over the Midwest in 1871, igniting not only the great Chicago Fire but

the huge forest fires that erupted the same night near Peshtigo, Wis., and Manistee, Mich.

In more recent history, a relatively tiny meteor exploded with a huge bang in the atmosphere over Park Forest, Ill., on March 27, 2003, causing roof damage to several homes and scaring the wits out of a lot of people.

"Occurring during Iraqi Freedom, many witnesses worried this meteor disintegration was some kind of massive explosion or nuclear event," concluded a study on the event conducted by the Aerospace Corp.

This week's conference, however, was devoted to more than preaching to the choir about the peril posed by massive rocks tumbling around in the darkness. The next step will be to develop a defense strategy and convince some government agency to shoulder the carry the immense responsibility of saving mankind.

Efforts are currently under way to locate and catalog the "Near Earth Objects (NEOs) that could someday wind up on an intercept course with Earth. The next step will be to develop a plan to deal with such a collision.

There are plenty of plans for futuristic anti-asteroid defenses being offered up for discussion. They include zapping them with an airborne laser system that is being developed by the Air Force for use against missiles, deploying dozens of small space drones that would team up to push an asteroid out of harm's way, and detonating a nuclear device close enough to break a NEO into smaller pieces.

All of these ideas, however, will have to first get a green light from policy makers who will demand solid proof that an asteroid is indeed bearing down on Earth before they launch an interception mission or start mass evacuations of cities and coastal areas.

Such proof will involve a lot more painstaking preparatory telescope work in order to develop a complete catalog of NEOs and their likely orbits over periods of several decades.

"There has to be a meeting of the minds at the Department of Defense and NASA to determine the next level of the search," Yeomans said. "If we don't have a good fix on their orbit, its not a very good idea to have great uncertainty out there among the public and the media."

A lot of the uncertainty, some of the scientists agreed, could be erased simply by cataloging NEOs and determining if their projected orbits will indeed ever pose a threat to Earth.

"Most likely, we're not going to find anything," predicted MIT's Jenifer Evans, co-author of a NASA feasibility study on expanding the search for NEOs. "We're looking at a statistical risk of the unknown."

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Hil Anderson is UPI's West Coast Correspondent. E-mail sciencemail@upi.com