Largest 1kg-heavy meteorite fragment found in Chelyabinsk region
"The biggest piece weighs over one kilogram; the precise weighting is still ahead," he said.
About 30 skiers of the university tourist club participated in the expedition, Grokhovsky said.
"They were divided into groups and skied for 50 kilometers. Some groups found meteorite pieces and some did not," he said.
Most of the meteorite debris has yet to be collected, but it is hard to say when the expeditions may continue, he said.
The university expedition brought about 50 meteorite pieces found near a hole on the Lake Chebarkul on February 17. The pieces were smaller than one centimeter in size. The scientists identified the meteorite as a regular chondrite, a stony meteorite containing about 10% of iron.
Grokhovsky supposed that the bulk of the meteorite up to 60 centimeters in diameter might have sunk in the lake. Much bigger fragments were found south of Chelyabinsk later. The researchers said the Chelyabinsk region had witnessed a stony meteor shower.
According to experts, the object that crashed into the Baltic was either a meteorite or a bolide. On February 20th a fireball lit the skies over Estonia, Latvia and Finland. Judging by witnesses’ accounts, there was a powerful explosion. In the opinion of the Latvian Astronomy Center, the meteorite could have landed into the Gulf of Riga.
The Chelyabinsk meteorite, weighing 10,000 tons, exploded above the Urals on February 14th . Fragments of it were scattered in and outside Chelyabinsk and Kopeyisk. The biggest fragment of it is believed to have fallen into Lake Chebarkul. The shockwave from the blast smashed windows. More than 1,500 people sustained injuries and 7,500 buildings were damaged. The Chelyabinsk administration will pay each resident who suffered in the event up to 50,000 rubles in compensation. The total loss inflicted by the meteor strike is estimated at one billion rubles.
Scientists have managed to gather about 50 small fragments near Chebarkul. Using supersensitive equipment, they have established that the object was a typical stone meteorite. Viktor Grokhovsky of the Ural Federal University leads an expedition in search of meteorite fragments.
"The meteorite that crashed into Lake Chebarkul was an ordinary chondrite consisting of minerals, including olivine, pyroxene, troilite, and kamacite. A meteorite is distinguished by the presence of minerals that form a particular combination which is not found on the Earth."
Experts have refuted Internet reports that the Chelyabinsk meteorite brought new bacteria. Mineral compounds in the found fragments are stable and reveal no presence of carbonaceous chondrite which could contain organic compounds. Unfortunately, the large fragment that cut an eight-meter hole in Lake Chebarkul is yet to be traced.
The question that has been asked in connection with the event is why the 10,000-ton meteor flew undetected by any of observation stations on the ground until it entered the Earth’s atmosphere. Mikhail Nazarov is Deputy Chairman of the Russian Academy of Sciences’ Meteorite Committee.
"The fireball traveling in outer space at a speed of about 30 kilometers per second was too small to be detected from the Earth. We can observe it for about half a minute as it hits the atmosphere. In half a minute we can only try to predict where it could fall and its energy. Taking any preventive measures to evacuate the population over such a short time is impossible."
Chairman of the Russian Security Council Nikolai Patrushev said in his comments on February 19th that the Chelyabinsk event had underscored the need to work out an international meteor defense program. It’s impossible to guarantee an effective protection against space objects singlehanded. For this reason, countries should unite their efforts to fend off asteroid-related threats. Andrei Ionin of the Russian Academy of Cosmonautics, comments.
"The threats coming from meteors and asteroids have to be addressed by joint efforts. The danger coming from asteroids has been under discussion for a long time. It’s time to devise an international arrangement for dealing with such threats. The asteroid issue should come before space exploration projects."
As it turned out, Russian scientists have worked out a meteor defense system and it was approved by the Roskosmos Space Agency last year. However, the system which includes space-based telescopes, was found too costly – 58 billion rubles, or nearly $2 billion, for 10 years. Now, the related agencies will have to re-estimate the costs in favor of endorsing the expenditure.
Meanwhile, life in Chelyabinsk is coming back to normal. One third of people hospitalized in connection with the meteor strike were released from hospitals on Friday. More than 4,000 out of 5,000 damaged buildings have been provided with new windows. While meteors are roaming outer space, life on the Earth is back to normal.
Voice of Russia, Interfax