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Nov. 6, 2013
Dr. David Morrison (SETI Institute and NASA Ames Research Center)
In February 2013, a rocky projectile entered the Earth's atmosphere traveling at more than 11 miles per second. It was about 65 feet in diameter and its explosion, at an altitude of 14 mi, released energy of about half a megaton, equivalent to a couple dozen Hiroshima-sized atom bombs. About two minutes later, the shock wave reached the ground in Chelyabinsk, Russia, breaking windows and injuring about 1500 people from flying glass. It struck without warning. Has this event served as a kind of cosmic wake-up call for planetary defense? NASA recently announced a 'grand challenge" to find all asteroids that could threaten human populations, and to figure out how to deal with them. David Morrison, a nationally-recognized expert about asteroids, discusses the Chelyabinsk impact and evaluates ways we might meet the grand challenge to protect our population from space impacts.