The Chelyabinsk Meteor: A Cosmic Wake-up Call?

What would happen if a large sized asteroid or space object collided with the Earth? On February 15 2013, a rocky projectile entered the Earth's atmosphere traveling at more than 11 miles per second. It was about 65 feet in diameter, or half the diameter of the famous Tunguska impact of 1908, which flattened a thousand square miles of Siberian forest. Its terminal 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. The Chelyabinsk impactor was smaller than most asteroids that have been detected by the telescopes of the NASA Spaceguard Survey, which focuses on finding asteroids of about 100m or larger. Since it approached the Earth from very near the direction of the Sun, it could not have been seen by any ground-based optical telescope of any size. It therefore struck without warning. Has this event  served as a kind of cosmic wake-up call for planetary defense? NASA scientist David Morrison will speak to us about how we survey space to try to determine when Earth will be impacted by a large space object, and what the potential implications could be for life on Earth.

Speaker: David Morrison, NASA Lunar Science Institute