Russian meteor a 'wake-up call for humanity'Wednesday 06 November 2013 23.03
An analysis of the explosion of a meteor over Russia earlier this year, which injured hundreds of people, has led to a warning from scientists that the incident was a wake-up call to humanity.
Three research papers by teams of international scientists published this evening in the journals Science and Nature, reveal the blast was equivalent to that produced by around 6500,000 tonnes of TNT.
One of the papers also warns that the number of similar-sized asteroids that pose a threat to Earth may be ten times greater than previously thought.
The meteorite struck the densely populated area around Chelyabinsk in Russia in February, blowing windows out of buildings, knocking people off their feet and injuring more than 1,600 people.
It was the largest meteorite strike since 1908 and thanks to modern technology such as mobile phones, CCTV and dashboard cameras, the incident was captured on video.
Using information gathered from these sources, including 400 cameras, and visits to 50 towns and villages, three teams of scientists comprised of dozens of researchers were able to piece together the details of the event.
In one paper published in Science, one team of 58 researchers from nine countries, claim the explosion caused by the asteroid entering the earth's atmosphere was the equivalent of about 600,000 tonnes of TNT.
Damage was caused 90km either side of the trajectory.
The team's modelling shows the impact was caused by a 20-metre single chunk of rock that broke up 30km above the earth's surface. As it did so, it was travelling at 19km per second.
Most of the material burned up, with the rest converted to dust and 0.05% or 4-6,000kg falling to the ground as meteorite.
Its brightness peaked at an altitude of 29.7km as it exploded, and a separate paper in Nature claims the resulting flash or airburst was 30 times brighter than the sun. As a result, many people on the ground reported sunburn-like symptoms.
The largest piece of meteorite recovered was found in Lake Chebarkul and weighed 650kg.
The paper published in Science claims the object was an ordinary chondrite - the most common type of meteorite - likely to be 4,452 million years old, which went through a shock event 115 million years after the solar system was formed.
One of the Nature studies claims the asteroid is similar to another that has orbited close to Earth, suggesting the two were probably once part of the same object.
A separate paper in Nature predicts that the number of objects with diameters in the range of tens of metres that pose a threat may be ten times greater than previously thought.
As a result, scientists involved in the studies have warned new technology for early detection of these objects is needed.
The asteroid was not spotted in the weeks before its impact because it spent the time in a region of the sky inaccessible to ground-based telescopes.
Models suggest that in any 20-year period, there is a 13% chance of an airburst as large as the one in Chelyabinsk.