Credit: Science/AAAS
The meteor that exploded over Chelyabinsk, Russia in February 2013 was "a wake-up call," according to a University of California, Davis scientist who participated in analyzing the event.
The work is published November 7, 2013 in the journal Science by an international team of researchers.
"If humanity does not want to go the way of the dinosaurs, we need to study an event like this in detail," said Qing-Zhu Yin, professor in the Department of Earth and Planetary Sciences at UC Davis.
Chelyabinsk was the largest meteoroid strike since the Tunguska event of 1908, and thanks to modern technology from consumer video cameras to advanced laboratory techniques, provides an unprecedented opportunity to study such an event, the authors note.
The Chelyabinsk meteorite belongs to the most common type of meteorite, an "ordinary chondrite." If a catastrophic meteorite strike were to occur in the future, it would most likely be an object of this type, Yin said.
The team was led by Olga Popova of the Russian Academy of Sciences in Moscow, and by NASA Ames and SETI Institute meteor astronomer Peter Jenniskens, and included 57 other researchers from nine countries.
"Our goal was to understand all circumstances that resulted in the damaging shock wave that sent over 1200 people to hospitals in the Chelyabinsk Oblast area that day," said Jenniskens.
The explosion was equivalent to about 600 thousand tons of TNT, 150 times bigger than the 2012 Sutter's Mill meteorite in California.
Based on viewing angles from videos of the fireball, the team calculated that the meteoroid entered Earth's atmosphere at just over 19 kilometers per second, slightly faster than had previously been reported.
"Our meteoroid entry modeling showed that the impact was caused by a 20-meter sized single chunk of rock that efficiently fragmented at 30 km altitude," Popova said.
A meteoroid is the original object; a meteor is the "shooting star" in the sky; and a meteorite is the object that reaches the ground.
Shock melt veins are weak sections along which meteorites can fragment.
Credit: M. Zolensky/NASA JSC
The meteor's brightness peaked at an altitude of 29.7 km (18.5 miles) as the object exploded.
For nearby observers it briefly appeared brighter than the Sun and caused some severe sunburns.
The team estimated that about three-quarters of the meteoroid evaporated at that point.
Most of the rest converted to dust and only a small fraction (4,000 to 6,000 kilograms, or less than 0.05 percent) fell to the ground as meteorites. The dust cloud was so hot it glowed orange.
The largest single piece, weighing about 650 kilograms, was recovered from the bed of Lake Chebarkul in October by a team from Ural Federal University led by Professor Viktor Grokhovsky.
Photo courtesy of Andrey Yarantsev.
For more information, please see Figure S53D in the Supporting Online Material. Credit: Science/AAAS
More information: "Chelyabinsk Airburst, Damage Assessment, Meteorite Recovery, and Characterization," by O.P. Popova et al. Science, 2013.
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