Summarized Facts About Russian Asteroid Impact

First Posted: Feb 19, 2013 04:22 PM EST

For the astonishing 15 February asteroid impact in Russia, detailed information becomes now available after astronomers and other scientists calculated the exact trajectory and parameters of the rock. The European Space Agency now released the results of their own assessment of the largest asteroid impact on Earth, with the data being a key input for developing the Agency's asteroid-hunting effort, which we reported on in January.

The natural object entered the atmosphere at 03:20 GMT on 15 February and subsequently disintegrated in the skies over Chelyabinsk, Russia.

"Extensive video records indicate a northeast to southwest path at a shallow angle of 20° above the horizontal. The entry speed is estimated at around 18 km/s - more than 64 000 km/h.

According to calculations by Peter Brown at the University of Western Ontario, Canada, drawing on extremely low-frequency sound waves detected by a global network, the object is estimated to have been about 17 m across with a mass of 7000-10 000 tonnes when it hit atmosphere." He also calculated the object's likely orbit around the sun.

With such a large mass, the estimated explosion force of nearly 500 kilotons of TNT - or some 30 times the energy released by the Hiroshima atomic bomb - is less unbelievable, but still astonishing. Since it happened around 15-20 km above the ground, the devastation wasn't much larger than it was, with around 1200 people injured by bursting windows.

With our current knowledge of near-Earth objects, events of this magnitude are expected to happen only a few times every 100 years.

Nicolas Bobrinsky, Head of ESA's Space Situational Awareness (SSA) programme, and Detlef Koschny, responsible for the programme's Near-Earth Object activity, responded to questions about the event. They said that the trajectory, the location of entry into the atmosphere and the large time separation between the two events indicate that the Russian object was unrelated to 2012 DA14, which passed Earth at 19:27 GMT that same day at just 28 000 km.

About what caused the damage: "Many media reported that an airburst caused window breakage and some structural damage in downtown Chelaybinsk. Normally, some damage begins to occur at around five times normal air pressure at sea level. Widespread window damage is expected around 10-20 times this value.

As the explosion and fireball progressed along a shallow trajectory, the cylindrical blast wave would have propagated directly to the ground and would have been intense.

The terminal part of the explosion probably likely occurred almost directly over Chelyabinsk. This was perhaps the single greatest contributor to the blast damage.

We are waiting for confirmation from the Russian authorities that pieces of the object - bits of meteorite - have been found in the region. We're unaware of any media reports of anyone or any structure being hit by any debris from the object itself."

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