Blast from Russian Meteor Similar to Nuclear Explosion
The atmospheric blast from the meteor that struck near the Russian city of Chelyabinsk this morning released 300 kilotons of energy, similar to a nuclear explosion according to a NASA expert. The resulting shock wave broke windows and collapsed walls, injuring more than 1,000 people.
Bill Cooke of NASA's Marshall Space Flight Center said in a media teleconference this afternoon that the force of the blast was determined by measurements from a global network of sensor arrays called Infrasound. The Infrasound system of 60 sensor arrays around the world was designed to detect nuclear explosions as part of monitoring compliance with the Comprehensive Nuclear Test Ban Treaty. He said NASA used data from four of the sensor stations to determine the amount of energy released by the blast. He expects other sensor arrays also picked it up, but did not know how many.
Videos of the meteor taken by cell phone and dashboard cameras by many of those who witnessed the event are posted on the Internet and tell more of the meteor's story, according to Cooke and Paul Chodas of the Jet Propulsion Laboratory (JPL).
Asteroids are rocks in space. Those that enter Earth's atmosphere are called meteors and if they reach the ground they are meteorites.
This meteor is estimated to have been 15 meters in diameter with a mass of 7,000 metric tons and travelling at 18 kilometers per second (40,000 miles per hour). It penetrated the atmosphere at an angle of 20 degrees and streaked through the sky for 30 seconds before breaking apart 20-25 kilometers (12-15 miles) above the surface of Earth.
Chodas said this was a "tiny" asteroid and could not have been detected in advance not only because of its size, but because it came from the daylight side of Earth. Using Earth-based telescopes, asteroids can only be detected against the black background of space -- at night. Asteroids the size of this one reach the surface about once every 100 years, he said. Cooke said the Earth actually intercepts 80 tons of meteoritic material every day, with "millions of millimeter size meteors striking Earth per day." Chodas added that meteors the size of basketballs hit Earth every day on average, while those the size of a car hit every month or two.
The fact that an asteroid hit Russia on the same day as asteroid 2012 DA14 made a close pass of Earth was a rare coincidence, Chodas said, but the two were not related to each other. Asteroid 2012 DA14 travels in an Earth-like orbit, while the asteroid that hit Russia came from the asteroid belt. The Russian meteor came from the opposite direction and its velocity was "much, much greater" than DA14, he stressed. No verified fragments from the meteor have been located so far, but Cooke expects that it was a common stony asteroid, not one made of iron.
Rep. Lamar Smith (R-TX), chairman of the House Science, Space and Technology Committee, issued a press release saying the two events today "are a stark reminder of the need to invest in space science," and promised to hold a hearing on ways to "better identify and address asteroids that pose a potential threat to Earth." A date for the hearing was not announced, only that it will be "in the coming weeks."
Correction: An earlier version of this article incorrectly stated that the energy released was 300 megatons, rather than 300 kilotons, of energy.
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