Asteroid to hit the Earth

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Interest in Asteroid Hunting Expands
January 22, 2002 08:00 CDT

Last week's close encounter with an asteroid has brought new interest in the potential for one to strike the Earth with devastating results. While NASA has embarked on an ambitious program to count and predict asteroid paths, including shooting a projectile at one, a UK scientist worries that no one is watching asteroids in the southern sky.

Dr. Duncan Steel, an expert in the detection of meteors, asteroids and comets at Salford University, UK, warns that humans must learn the lessons from 65 million years ago, when it is thought the impact of a giant space rock on the planet accelerated the end of the dinosaur dynasty.

When an asteroid called 2001 YB5 whizzed past the Earth Jan. 7, it missed the planet by more than 300,000 miles - but, at the speed the Earth is traveling in its orbit, that distance accounts for only a few hours. The asteroid was probably 980 feet across. When a large body estimated at only 160 feet in size exploded above the Siberian forest in 1908, it flattened trees over a wide area.

"I think it would be grossly stupid of us not to tackle it head on," Steel told the BBC's World Service's Discovery program.

Much research is being done to investigate how the Earth might protect itself against any future strike. But with much of the southern hemisphere sky unpatrolled by asteroid and comet-seeking telescopes, it is clear efforts to stave off some future, apocalyptic event could be stepped up.

To date, there is no record of anyone having been killed by an asteroid impact but the devastation that would be caused by a large one is so terrible that, statistically, you are more likely to die from a space-rock impact than in a plane crash.

A less frequent threat but one that could be even more deadly and even harder to predict is that of a comet.

Comets come from the frozen outer reaches of the Solar System and are very difficult to spot before they reach the distance of Jupiter, by which time it could be too late to plan a defense. So what are scientists doing to prevent collision?

An ambitious NASA space probe under construction plans to strike back as project worker, Peter Schultz of Brown University, Rhode Island, told BBC: "We're going to have some revenge on a comet called Tempel 1 with the Deep Impact mission." The Deep Impact mission hopes to reveal the nature of the threat and how to deflect it safely. On American Independence Day 2005, Deep Impact will reach its target, the six-kilometer diameter comet Tempel 1.

The space probe will release a 770-pound projectile into the heart of the comet at six miles per second. It is expected to blow a crater the size of a football field and 65 feet deep. The comet will survive but should reveal the nature of its interior to add to scientific knowledge and to guide any future plans to deflect a killer comet with a nuclear nudge.

Meanwhile, the search for comets and asteroids is stepping up.

So far, it is centered in the U.S., though teams in Japan and Britain are setting up information centers and may adapt telescopes in the Canary Islands to join the search. But, a telescope powerful enough to see a small asteroid can only search a small strip of sky at a time and at present no one is searching in the southern hemisphere.

This worries Steel, who used to run a search program in Australia. "A third of the sky is currently not being searched because there is no Southern Hemisphere search program," he told the BBC. "In essence, at the current time, our back door is open because no one is looking down there."

Source: BBC

Cosmiverse Staff Writer