THE VIRGINIAN-PILOT
Copyright (c) 1995, Landmark Communications, Inc.
DATE: Wednesday, May 17, 1995 TAG: 9505170048
SECTION: LOCAL PAGE: B1 EDITION: FINAL
SOURCE: BY JAMES SCHULTZ, STAFF WRITER
DATELINE: HAMPTON LENGTH: Medium: 77 lines
Chicken Little was right. The sky does fall. When it does, death - and, sometimes, life - follow.
Astronomers Eugene and Carolyn Shoemaker, co-discoverers of a comet that bore their name, Tuesday announced the latest findings from last July's spectacular collision between the planet Jupiter and fragments of the Shoemaker-Levy comet. The husband and wife team addressed a packed auditorium at NASA Langley Research Center.
One provocative post-impact discovery announced by Eugene Shoemaker was elevated levels of water vapor, 10 times the amount normally expected. The water was released when pieces of the comet's ice-covered rock disintegrated in the upper reaches of the Jovian atmosphere.
Along with the water could have come organic molecules - molecules that, under the right conditions, may jump-start evolution. Life on Earth could very well owe its origins to outer space because of a similar extraterrestrial visitation.
``Comets bring basic building blocks,'' Carolyn Shoemaker said. ``They play an essential part in the evolution of life.''
Another collision conclusion: the Jupiter incident vividly illustrated the process that many scientists believe killed all dinosaurs on Earth some 65 million years ago.
Then, or so the theory goes, an asteroid the size of Mount Everest slammed into the waters somewhere near present-day Central America, releasing more than 10,000 times the combined energy of current Russian and American nuclear arsenals. Soot from a global firestorm and trillions of tons of debris were thrown into the upper atmosphere, obscuring solar radiation.
The intensely black clouds that pockmarked Jupiter's face in the aftermath of the July, 1994, impacts would have, if experienced on Earth, blocked sunlight and lowered planetary temperatures fast and far enough to kill most animal and plant life.
``It's a direct demonstration of the dinosaur extinction hypothesis,'' said Eugene Shoemaker. ``These kind of impacts have been going on throughout the history of the Earth. (Today) it could cause a major global catastrophe. A major fraction of the population could starve to death.''
NASA has formed a working group chaired by Eugene Shoemaker to examine the planetary threat from errant asteroids and comets. Next week, the group will submit a second draft of a report that recommends a modest $4 million effort to use mostly ground-based observatories to track potential celestial threats.
Any imminent collision is unlikely through the next century, Eugene Shoemaker said, citing a 1-in-1,000 collision chance. One reason is the gravitational protection offered by Jupiter and Saturn, Uranus and Neptune, the three other gas-giant planets that lie beyond Jupiter.
The quartet act as a short of interplanetary shepherd, herding asteroids and comets into vast orbits well beyond Earth's gravitational reach.
Most scientists agree that even if the worst were to come to pass, nuclear-tipped missiles sent deep into space would likely be able to nudge any Earth-bound comet or asteroid toward a nondestructive path.
Shoemaker would like to see the nation's space program gear up to land probes on the largest of the solar system's comets and asteroids to better understand their origins and composition. ``It's a very exciting area scientifically,'' he said.
Given the deep federal budget cuts being proposed, new space-based initiatives don't seem likely. Still, the threat of an asteroid or comet collision with Earth would likely be enough to quickly reorganize political priorities and galvanize a space program that, for now, aims for more modest space exploration goals close to home. ILLUSTRATION: Photo
When the Shoemaker-Levy comet struck Jupiter recently, its vaporized
ice, upper right, may have contained organic molecules. Under the
right conditions they could be the building blocks of life. At lower
left is a Jovian moon.
by CNB