Wednesday, March 27, 2013

Meteorites reveal the secrets of last month's Russian fireball

Shards of meteorite, remnants of the fireball that streaked across Russia's skies on February 15, are giving scientists clues to the composition and origin of the space rock.

By Leonard David,?Space.com / March 21, 2013

A meteor streaked across the sky of Russia?s Ural Mountains on Friday morning, Feb. 15, causing sharp explosions injuring over 100 people, including many hurt by broken glass. Scientists have recovered broken fragments of the superbolide and are examining them for clues to its origin.

Nasha gazeta, www.ng.kz / AP

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Scientists studying small pieces of the meteor that exploded over the Russian city of Chelyabinsk on Feb. 15 are working to glean new insights into the rare impact by a space rock.

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Based on the meteorite analysis, researchers have determined that last month's meteor explosion in Russia ? which scientists call a superbolide ? produced a shock wave that reached the ground. That shock shattered windows and injured some 1,500 people due to flying glass.

The blast also created a shower of stony meteorites that fell to Earth in an impact region more than 60 miles (100 kilometers) long.

Thinly sliced meteorites

Some of the Chelyabinsk meteorite samples have made their way to planetary scientist Larry Taylor, director of the Planetary Geosciences Institute at the University of Tennessee in Knoxville, who obtained the superbolide samples with the help of Russian colleagues.?

"I got three pieces that were completely coated with black fusion crust. The total of them is less than 10 grams," Taylor told SPACE.com here at the 44th Lunar and Planetary Science Conference.

Initially, the meteorite specimens were polished and thinly sliced for a detailed inspection under a petrographic microscope. The device is a type of optical microscope used in petrology and optical mineralogy that scientists are employing to identify rocks and minerals within the thin meteorite slices.

The small samples will undergo further scrutiny over the next few months, Taylor said.

"We've just started to skim the top of it," he added.

Tapping into superbolide secrets

Taylor and his associates are now deciding the best tactics to further reveal what stories the specimens have to tell.

"The magnitude of the explosion led a whole lot of us to believe that it must have been a very volatile-rich meteor that was coming in ? because it exploded so vigorously," Taylor said. Volatile materials are those that evaporate easily. ?In fact, everything we found so far points to an ordinary chondrite."

About 90 percent of stony meteorites are classified as ordinary chondrites, space rocks that are lacking in volatile materials.

"It is ordinary because it's common," Taylor said. "But it is special because it contains such a wide array of things ? a whole menagerie of things all in one."?

Source: http://rss.csmonitor.com/~r/feeds/science/~3/-mNZ-WM7BWo/Meteorites-reveal-the-secrets-of-last-month-s-Russian-fireball

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