Meteorites: Hunting missiles from outer space

(CBS News) When a meteor fell out of the blue and exploded with enormous power over Russia this past week, people all over the world took notice, and began looking anxiously UP into the sky ourselves. There is a lot going on up there, much of it untrackable. But true experts in the field are often looking DOWN, hunting for those cosmic bits and pieces underfoot that have fallen and KEEP falling all the time. Rita Braver reports our Cover Story:

The meteor that shot through the sky over Central Russia on Friday, exploding into a shower of fireballs, created sound waves that were felt for miles. More than twelve hundred people were injured, shattered glass was everywhere, and thousands of buildings were damaged.

Though meteors do fall frequently, such devastating events are rare. But remember, many scientists believe it was an asteroid smashing into the Earth some 65 million years ago that caused wildfires that changed the environment so much, dinosaurs could no longer survive.

And for generations, humans have been trying to understand the hows and whys of these missiles from outer space.

The Smithsonian's Museum of Natural History has amassed a major collection of them, overseen by Linda Wellzenbach, and its exhibit of meteorites is the largest in the world, including some which look like sculpture.

"Iron meteorites are really interesting in many ways, because they are fragments of an asteroid that has been completed disrupted. So we're getting pieces of something that at one time was a full planet," she said.

In fact, most of the meteorites that land on Earth come from the asteroid belt, an area between Mars and Jupiter, where space debris collects.

And here's a little space terminology:

Asteroids are minor planet-like objects that usually orbit the sun. Meteoroids are much smaller bodies. When either enters the Earth's atmosphere, they are known as meteors. And when they hit the Earth, they are called meteorites.

The Smithsonian has about 50,000 meteorites in its collection. "Why are you still trying to get more?" asked Braver.

"Because every single one is a puzzle piece that adds to the information that we understand about the history of our solar system and the history of the development of the Earth," Wellzenbach said.

In fact, meteorites are so sought after that a little-known federal government program -- the Antarctic Search for Meteorite program, or ANSMET -- sends scientists (including Wellzenbach) on annual expeditions.

Ralph Harvey, associate professor of planetary science at Cleveland's Case Western Reserve University, has been leading the 37-year-old program since 1991.

He says it's not that there are more meteorites in Antarctica than the rest of the world, but that they are better preserved in the frigid landscape.

"There are meteorites we've collected in Antarctica, where they're so young we can't measure that age," Harvey said. "There are others we found that fell several million years ago. And there's everything in-between. The average seems to be about 25-30,000 years."

To the scientists' delight, they've even found samples from the Moon and Mars.

"This is an Easter egg hunt unlike any Easter egg hunt anywhere," he said. "When somebody sees one, they stop, and their first job is to do a little dance, and then we all converge on the site."

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