It's a bird, it's a plane, it's a meteor

By Jayne Spencer

Doom happens.

Nelson Shaffer will tell you that, but not in a particularly dark way. Perhaps it's just an occupational preoccupation for those who track meteors.

Shaffer and Abhijit Basu are colleagues at the Indiana Geological Survey, headquartered on the IU Bloomington campus, and are Hoosier Indiana Joneses when it comes to meteor treasures.

Here are the facts. More than 200 impact craters have been found on Earth, and many more can be seen on the moon and other planets. Impacts can cause great destruction, and one very large event may have played a role in the demise of the dinosaurs. Indiana has a probable meteorite impact structure at Kentland in the northwest part of the state.

And, Shaffer said, NASA and other agencies are mounting efforts to track potentially dangerous asteroids. "We receive reports from time to time of asteroid near misses, but others probably pass unnoticed," he said. "In history, only a very few animals have been hit by meteorites, and relatively few meteorites have even hit structures."

A meteor, Shaffer explained, is the flash of light (and other radiation) that occurs when a meteoroid (a rocky fragment orbiting the sun) enters the atmosphere and is decelerated. If the material survives the fiery flight and lands on Earth, it is then a meteorite. Many meteoroids become dust and can be micrometeorites which are studied by many scientists. Specialists in the study of meteorites generally are trained in chemistry, mineralogy, geology or physics.

"I examine several potential meteorites nearly every month. Real meteorites are very rare, but 13 have been recovered in Indiana," he said. (See map of "finds" at right).

In March 1882, a bright light bore down from the skies at Oswego, accompanied by a roaring sound and a color of molten red. When it exploded overhead, windows were shattered in Warsaw 11 miles away. A more recent meteorite fall occurred near Seymour at a railroad-highway intersection called Hangman's Crossing in May 1976. Shaffer and Basu did an assessment when the farmer who found it, C.F. Miller, presented it to his newborn grandson in 1987.

Why do scientists analyze such materials?

"For many years, meteorites represented the only specimens of material not from the Earth," said Shaffer. "Meteorites have given valuable information about the raw materials that made up planets and other bodies in our solar system. Certain exotic materials found in meteorites even pre-date our system and represent very ancient materials.

"In the last few years, meteorites from the Moon or even Mars have been recovered. Some think that signs of life have been found inside Martian meteorites. Subtle chemical details have allowed scientists to learn about solar and cosmic radiation."

Why has mankind, from the Ancients to contemporary film makers, been fascinated by "cosmic debris?"

"The universe is so very large and so very old that humans have no real meaningful points of reference," Shaffer speculated. "Meteorites tell us a likely age of the solar system and provide ample evidence for violent collisions in space -- violent enough even to produce small diamonds. Scars upon the Earth that have been made by large meteorite impacts do show that destruction has occurred, and many believe that impacts can cause mass extinctions on Earth."

"Meteorites tell us about themselves and about geologic processes," he said. "But they cannot tell much about man or his follies. You need to speak with an astronomer or philosopher about these larger things."