November 7, 2013
Chilling New Detailed Analysis Of Chelyabinsk Meteor Explosion
Brett Smith for redOrbit.com - Your Universe Online
A series of recently released papers dealing with the meteor that exploded over Chelyabinsk, Russia, in February, brought forth two startling conclusions: the damage could have been much worse, and these types of events could be much more common than previously thought.According to one of the reports published in the journal Science, the meteor over Chelyabinsk created a 500-kiloton explosion about 20 miles above the surface that caused sunburn, shattered windows, and knocked out both electricity and cell phone service.
Study authors said the meteor was probably broken off from a larger rock and littered the Earth with less debris than would have been expected if it were made of solid rock, iron and nickel as some near-Earth objects are.
Authors of all three studies recreated the meteor's path by examining videos of the event, tracking patterns of damage on the ground and talking to eyewitnesses.
"It was a huge amount of work," Western University's Paul Wiegert, author of one of the Nature studies, told NBC News. "It involved having people going out to the locations where it was observed, and even measuring the height of street lamps" to determine the meteor's approximate path.
According to the analyses, the meteor was about 60 feet wide, disintegrated at an altitude of about 20 miles, and released the equivalent of a 500-kilotons TNT explosion.
The Science paper reported that people heard the buzz of the passing meteor known as electrophonic sound. It also said the meteor's explosion was brighter than the sun, causing mild cases of sunburn, and knocking out both the electrical grid and cell phone networks.
Somewhat alarmingly, one of the Nature papers said we currently don’t have the capability to detect something the size of the Chelyabinsk meter before it enters the Earth’s atmosphere.
"The Chelyabinsk asteroid was simply too small to be seen at large distances from the Earth with current technology," Jiri Borovicka of the Astronomical Institute at the Academy of Sciences of the Czech Republic, told NBC News in an email. "It approached the Earth from the direction of the sun, but even if it came from the opposite direction, there would be high chance that it would have been missed by the current survey telescopes during the few days before the impact when it would be observable."
Another of the Nature papers examined records of meteor strikes that had hit the Earth in the last 40 years and saw many more instances than they expected based on surveys of near-Earth space. Previous estimates had calculated a Chelyabinsk-size meteor hitting Earth's atmosphere once every 150 years. However, researchers found multiple impacts over a comparable time span – closer to one every 30 to 40 years.
Paul Chodas, a NASA asteroid researcher, said that previous surveys pegged the number of near-Earth asteroids similar to the one that struck Chelyabinsk at around 3 million to 4 million. After reviewing the newly published papers, Chodas told reporters that "the implication is there are seven times more, so on the order of 20 million."