LONDON (AP) - They may only strike every 100,000 years on average, but life-threatening asteroids could be heading Earth's way, and scientists said Monday they want a closer look.
A panel set up this year by the British government to assess the risk of asteroids slamming into the planet called for an international program to build a powerful $22.5 million telescope in the southern hemisphere.
"The risk is very real - and very tiny - but with awful consequences, and we ought to be doing something about it," said Sir Crispin Tickell, Britain's former ambassador to the United Nations and a member of the panel, which published its report on Monday.
Although millions are already being spent trying to track Near Earth Objects, or NEOs, scientists acknowledge they're very much in the dark. Asteroids near Earth travel at between 10 and 20 miles per second, making them hard to detect. As a result, scientists watch their orbits to predict their expected course.
According to the U.S. space agency NASA, at the beginning of 2000, only about half the estimated 500-to-1,000 near-Earth asteroids measuring half a mile across or larger - big enough to cause a global catastrophe - had been detected.
The proposed 10-foot telescope would see further and wider and be able to pick up the faintest of glows, the panel said. Operated robotically, it would supplement the coverage of other telescopes in operation in the northern hemisphere.
"It's a question of giving ourselves a chance," said Robert Massey, an astronomer at Britain's Royal Observatory in Greenwich. "We would be able to spot trouble 10 to 100 years away and could take steps accordingly."
"On the other hand, if it were a year away, probably the best we could do would be to duck," Massey said.
Objects hitting the Earth have caused devastating damage over millions of years. One impact off the coast of what is now Mexico 65 million years ago is thought to have led to the extinction of the dinosaurs.
Another impact in 1908 in Siberia knocked down trees with its shock waves over hundreds of square miles.
The report listed nine objects that have come within two lunar distances of the Earth - about 497,120 miles - since 1991. In May 1996, an object 984 feet wide, called JA1, came as close as about 298,000 miles to the planet.
It also called for further study into how to destroy a sizable object on a collision course with the planet. One possibility is a nuclear explosion by the side of an asteroid to divert it from its course.
Recent Hollywood blockbusters "Armageddon" and "Deep Impact" have heightened public awareness about asteroid disasters.
NASA has already earmarked more than $1 billion to gain a better scientific understanding of asteroids, which are rocky or metallic bodies hurtling through space mostly in a band between Jupiter and Mars.
One British lawmaker, whose grandfather had an asteroid named after him to acknowledge his lifelong campaign to warn of impending disaster, welcomed Monday's proposal.
"We are playing Russian roulette with the future of the planet if we do nothing about it," said Lembit Opik. "It would be a bit like Armageddon, but probably we would not want to send Bruce Willis."
The panel is chaired by Dr. Harry Atkinson, formerly of the Science and Engineering Research Council and a past chairman of the European Space Agency's council.