The first firm details of the 15 February asteroid impact in Russia, the largest in more than a century, are becoming clear. ESA is carefully assessing the information as crucial input for developing the Agency’s asteroid-hunting effort.
At 03:20 GMT on 15 February, a natural object entered the atmosphere and 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.
It exploded with a force of nearly 500 kilotons of TNT - some 30 times the energy released by the Hiroshima atomic bomb - around 15-20 km above the ground.
With our current understanding of near-Earth objects, events of this magnitude are expected once every several of tens to 100 years.