A RUSSIAN scientific expedition is claiming that a gigantic meteor, large enough to flatten a small city, exploded over Siberia last year. But the report has been met with extreme scepticism.
According to the Russian news agency Interfax, a team of volunteers has found an impact area covering about 100 square kilometres of remote Siberian woodland. That would make it the second largest meteor strike in the past century, after the famous Tunguska impact of 1908. 鈥淚 would love them to be right, because useful scientific data would come from this,鈥� says Duncan Steel from the University of Salford in the UK, who studies asteroids.
Such an impact would also force astronomers to revise their estimates for the likelihood of a devastating asteroid striking Earth. But Steel and other scientists contacted by 快猫短视频 say the facts just don鈥檛 square with this interpretation.
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American satellites spotted the object in September 2002 as it entered the atmosphere, but lost track of it as it fell below 30,000 metres. Most meteors explode at altitude, when they are broken up by the decelerating force exerted by the atmosphere. A second American satellite picked up the explosion and estimated its size as between 0.2 and 2.4 kilotons, a fraction of the 10 megatons that Tunguska is thought to have been. An explosion of this size is unlikely to cause a lot of damage. 鈥淚 would expect it to go bang at about 10 to 12 kilometres high and cause no damage on the ground, except knocking the odd piece of crockery from people鈥檚 shelves,鈥� says Steel.
The object could have been a relatively rare type of meteor made of nickel and iron. These tend not to break up on entry, so they hit the ground and cause craters. But even then the explosion should not have caused catastrophic damage. 鈥淎t most it would form a crater of about 30 metres in diameter,鈥� says Mikhail Nazarov, deputy director of the Russian Academy of Sciences meteorite committee at the Vernadsky Institute in Moscow.
In October, two scientists from the academy attempted to find the impact site, accompanied by four journalists. But despite using satellite data to pinpoint the site, the expedition could only find minor tree damage thought to have been caused by debris from the explosion. Heavy snowfall prevented further searches during the winter, but now a second expedition has been mounted by members of Kosmopoisk, an organisation of 300 volunteers who coordinate searches for space debris. They claim to have found an extensive area of burnt trees and meteorite fragments 60 kilometres from the village of Mama, near the Irkutsk border.
But scientists remain sceptical. 鈥淭here are no experts on this expedition,鈥� says Nazarov. The team claims to have fragments of the meteorite, and Nazarov says he has asked to see them. 鈥淲e are waiting for samples.鈥�
One way to settle the matter would be to compare satellite images of the area before and after the supposed impact, says Brian Marsden, director of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts. If the damaged area shows up on pictures taken a year ago then it could not have been caused by the meteor.