PSI Senior Scientist Natasha Artemieva presented a recent seminar on what has been learned in the year following the Chelyabinsk impact event in Russia. On Feb. 15, 2013, thousands of people observed a bright fireball in the sky above the Ural Mountains, followed minutes later by a powerful sonic boom that broke windows over an area of about 2,000 square miles and injured 1,600 people.
Artemieva discussed the various approaches, including numerical modeling, to study all stages of the event – the meteoroid’s atmospheric flight and fragmentation, the surface damage caused by shock waves and the evolution of the smoke train. She said that so far, less than 1,000 kilograms of meteorite fragments have been recovered, representing less than 0.01 percent of the meteoroid’s preatmospheric mass. The largest piece fell into a lake and eight months later was recovered by divers from a depth of 18 meters. Its weight exceeds 600 kilograms, while the smallest specimens found are just a few milligrams. Much smaller micron-sized ablation products could be detected in the Earth’s atmosphere by space satellites until mid-April 2013.