THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Thursday, November 2, 1995 TAG: 9511020370
SECTION: LOCAL PAGE: B1 EDITION: FINAL
SOURCE: BY JAMES SCHULTZ, STAFF WRITER
LENGTH: Medium: 81 lines
Halloween's over. The goblins and ghouls are gone. So there you sit in your snug bungalow, not a fear in the world.
Until you go outside. Until you look up to the starry skies. Until you realize almost 3,000 asteroids and comets are whizzing around somewhere near Earth, altogether too close for comfort.
Because one of them could have your name on it. And mine.
``Comets and asteroids are the only natural hazards capable of destroying civilization,'' said John S. Lewis, principal scientist at the University of Arizona's Space Engineering Research Center. ``They can have truly devastating consequences.''
Tonight, in a talk at Old Dominion University, Lewis will spell out the dangers posed by, and possible ways of deflecting, these cosmic marauders on a collision course with Earth. Not surprisingly, Lewis says, the biggest threat comes from the largest heavenly bodies, those with a diameter of a half-mile or more.
``We get hit by these bodies once every few thousand years,'' he said. ``What would happen to Earth (today)? We'd lose 4 billion people. Maybe 5 (billion).''
Recently, scientists uncovered evidence that an entire 17th century Chinese village was wiped out by a meteorite, Lewis said. Then there was a 1908 impact in a remote Siberian forest that leveled trees for miles around.
Earlier this year, scientists confirmed that about 35 million years ago, a meteorite the size of a small mountain carved out an area that eventually became the Chesapeake Bay. The fault lines, fractured boulders and jumbled sediments found by researchers attested to the force of a blast which, if it occurred today, would destroy an area stretching from Virginia Beach and Norfolk up through Richmond and Washington.
A year ago this past July, the world watched in fascination as a string of comet fragments slammed into Jupiter, creating wounds the size of our home planet.
Another celestial visitor, 10 times the size of the Bay-forming meteorite, is thought to have contributed to the demise of dinosaurs 65 million years ago. That collision released the equivalent of 100 million tons of TNT, an explosion that likely started a global firestorm, which would have sent ash and soot high into the stratosphere, blocking sunlight and lowering planetary temperatures.
Lewis says that what is most dangerous about some of the smaller visitors is that their arrival just can't be predicted - at least, not yet. Even though astronomers are scouring the skies for celestial intruders, 90 percent of the orbits of near-Earth asteroids are still to be identified.
``There's no good place to land one of these on Earth,'' Lewis said. ``So we must deflect it. Blowing it up would be a bad idea. We'd be hit by shotgun blasts of debris.''
So, says Lewis, our best chance for avoiding catastrophe would be to outfit a nuclear-tipped rocket and explode the warhead near the errant wanderer. The resultant vaporization of surface rock and ice would likely be enough to nudge the invader out of Earth's way.
``We could whip together an interceptor in one year's time,'' Lewis said. ``We'd probably use a Russian Proton booster and a large nuclear warhead. Then we could play policeman and divert it.''
Fortunately, most asteroids and comets take awhile to reach Earth: several hundred years at a minimum. According to Lewis, there's just a small chance - one in 2,000 - that a city-size rock will scream through the atmosphere in the next 20 years.
But there's still that chance. So watch the skies. The marauders are out there.
One day, they'll be here. ILLUSTRATION: JANET SHAUGHNESSY/The Virginian-Pilot
Graphic
WHERE TO GO
John S. Lewis' talk,``Rain of Iron and Ice: Civilization at Risk''
will take place a 8 tonight in the auditorium of ODU's Mills Godwin
Building. The presentation is free and open to the public.
by CNB