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Russian meteor studied in detail

Nov. 6, 2013
Courtesy of the University of California - Davis
and World Science staff

The me­te­or that burst over Chel­ya­binsk, Rus­sia Feb. 15 was “a wake-up call,” ac­cord­ing to a Uni­vers­ity of Cal­i­for­nia, Da­vis sci­ent­ist who helped an­a­lyze the event. 

“If hu­man­ity does not want to go the way of the di­no­saurs, we need to study an event like this in de­tail,” said the plan­e­tary sci­ent­ist, Qing-Zhu Yin. New find­ings by Yin and col­leagues are pub­lished Nov. 7 in the jour­nal Sci­ence, along­side two oth­er stud­ies on the event pub­lished in the Nov. 8 is­sue of Na­ture.

Chel­ya­binsk was the larg­est me­te­oroid strike since the Tun­gus­ka event of 1908, al­so in Rus­sia, sci­ent­ists said. Mod­ern tech­nol­o­gy from con­sum­er vi­deocam­er­as to ad­vanced lab­o­r­a­to­ry tech­niques has pro­vid­ed an un­prec­e­dent­ed op­por­tun­ity to study such an event, they added.

The Chel­ya­binsk me­te­orite had al­ready crashed in­to some­thing pre­vi­ously, and be­longs to the most com­mon type of me­te­orite, an “or­di­nary chon­drite,” Yin and col­leagues said. If a cat­a­stroph­ic me­te­orite strike oc­curs in the fu­ture, it will most likely be an ob­ject of this type, they added.

In one of the Na­ture stud­ies, Jiøí Borovièka of the Acad­e­my of Sci­ences of the Czech Re­pub­lic and col­leagues said the Chel­ya­binsk as­ter­oid’s or­bit around the Sun seems to have been si­m­i­lar to anoth­er as­ter­oid that has ap­proached Earth, sug­gest­ing the two were probably once part of the same ob­ject. The oth­er as­ter­oid is an ob­ject dubbed near-Earth as­ter­oid 86039 (1999 NC43).

The team re­port­ing the find­ings in Sci­ence 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 1,200 peo­ple to hos­pi­tals in the Chel­ya­binsk Ob­last ar­ea that day,” said Jen­niskens. The ex­plo­sion was equiv­a­lent to about 600 thou­sand tons of TNT, the group added, 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 km (12 miles) per sec­ond, slightly faster than pre­vi­ously re­ported.

“Our me­te­oroid en­try mod­el­ing showed that the im­pact was caused by a 20-meter [or yard] sized sin­gle chunk of rock,” 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.)

The me­te­or’s bright­ness peak­ed at an al­ti­tude of 29.7 km (18.5 miles) as the ob­ject ex­plod­ed, ac­cord­ing to Yin and col­leagues. For near­by ob­servers it briefly ap­peared brighter than the Sun and caused some se­vere sun­burns.

The team es­ti­mat­ed that about three-quarters of the ob­ject evap­o­rat­ed then and there. Most of the rest turned to dust and less than one part in 2,000 fell to the ground as me­te­orites. The dust cloud was so hot it glowed or­ange.

Sci­en­tists re­port­ing in Na­ture pro­vid­ed si­m­i­lar es­ti­mates of the break­up height and the en­er­gy of the ex­plo­sion.

The larg­est sin­gle piece, weigh­ing about 650 kg (1,400 lb.), was reco­vered from the bed of Lake Chebarkul in Oc­to­ber.

Shock­waves from the air­burst broke win­dows, rat­tled build­ings and even knocked peo­ple from their feet. Popova and Jen­niskens vis­ited over 50 vil­lages in the ar­ea and found that the shock­wave caused dam­age about 90 kilo­me­ters (50 miles) on ei­ther side of the trajecto­ry. The team showed that the shape of the dam­aged ar­ea could be ex­plained from the fact that the en­er­gy was de­posited over a range of al­ti­tudes.

The rock probably fell apart more easily be­cause of abun­dant “shock veins” pass­ing through it, caused by an im­pact hun­dreds of mil­lions of years ago, said Yin and col­leagues. These veins would have weak­ened the orig­i­nal me­te­oroid; they were de­tected in a scan­ning study of the reco­vered rock from Lake Chebarkul.


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The meteor that burst over Chelyabinsk, Russia in February 2013 was “a wake-up call,” according to a University of California, Davis scientist who helped analyze the event. “If humanity does not want to go the way of the dinosaurs, we need to study an event like this in detail,” said planetary scientist Qing-Zhu Yin. New findings by Yin and colleagues are published Nov. 7 in the journal Science, alongside two other studies on the event published in the Nov. 8 issue of Nature. Chelyabinsk was the largest meteoroid strike since the Tunguska event of 1908, also in Russia, scientists said. Modern technology from consumer video cameras to advanced laboratory techniques has provided an unprecedented opportunity to study such an event, they added. The Chelyabinsk meteorite had already crashed into something previously, and belongs to the most common type of meteorite, an “ordinary chondrite,” Yin and colleagues said. If a catastrophic meteorite strike occurs in the future, it will most likely be an object of this type, they added. In one of the Nature studies, Jiøí Borovièka of the Academy of Sciences of the Czech Republic and colleagues said the Chelyabinsk asteroid’s orbit around the Sun seems to have been similar to another asteroid that has approached Earth, suggesting the two were probably once part of the same object. The other asteroid is an object dubbed near-Earth asteroid 86039 (1999 NC43). The team reporting the findings in Science 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 previously reported. “Our meteoroid entry modeling showed that the impact was caused by a 20-meter [or yard] sized single chunk of rock,” 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.) The meteor’s brightness peaked at an altitude of 29.7 km (18.5 miles) as the object exploded, according to Yin and colleagues. For nearby observers it briefly appeared brighter than the Sun and caused some severe sunburns. The team estimated that about three-quarters of the object evaporated then and there. 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. Scientists reporting in Nature provided similar estimates of the breakup height and the energy of the explosion. The largest single piece, weighing about 650 kg (1,400 lb.), was recovered from the bed of Lake Chebarkul in October. Shockwaves from the airburst broke windows, rattled buildings and even knocked people from their feet. Popova and Jenniskens visited over 50 villages in the area and found that the shockwave caused damage about 90 kilometers (50 miles) on either side of the trajectory. The team showed that the shape of the damaged area could be explained from the fact that the energy was deposited over a range of altitudes. The breakup was likely facilitated by abundant “shock veins” that pass through the rock, caused by an impact hundreds of millions of years ago, said Yin and colleagues. These veins would have weakened the original meteoroid; they were detected in a scanning study of the recovered rock from Lake Chebarkul.