Meteor lurked for thousands of years before blasting Russia, experts say..traced to Apollo asteroid family

Now that they're worked out the orbital path of the meteor that blew up over Russia last month, scientists are saying that the asteroid behind the blast crossed Earth's orbit regularly for thousands of years.

Based on the readings from infrasound sensors stationed all over the world to monitor nuclear-weapons tests, NASA said the energy release was equivalent to 500 kilotons of TNT, or roughly 30 times the energy released by the atomic bomb dropped on Hiroshima at the end of World War II. That translated into an object about 17 meters (55 feet wide), weighing 10,000 tons. The space agency said it was the biggest cosmic impact recognized since the 1908 Tunguska asteroid blast that leveled millions of trees in Siberia.


Less than a week after the blast, Colombian astronomers worked out a rough orbital path for the Chelyabinsk asteroid, based on an analysis of the videos captured by dashboard cameras and traffic cams in the area. On Friday, NASA produced a more definitive orbital track, based not only on the videos but also on the readings from the federal government's space sensors. The report took advantage of a recently signed agreement with the Air Force Space Command for the public release of previously hush-hush data.
Sizing up a superbolide
Friday's assessment is the first entry in a new NASA database for fireballs and bolide reports, which classifies the Chelyabinsk meteor as a "superbolide."
The latest readings confirm the conclusion that the object's orbit ranged from the main asteroid belt, beyond the orbit of Mars, to well within Earth's orbit. They also show that the Chelyabinsk asteroid's approach couldn't have been detected by ground-based optical telescopes because the space rock was hidden in the sun's glare.


"The impactor had likely been following this orbit for many thousands of years, crossing the Earth's orbit every time on its outbound leg," NASA's Near-Earth Object Program Office said in Friday's assessment.




link to article and image of asteroid's orbit


[link to cosmiclog.nbcnews.com]

Last Edited by *PinkPixie* on 03/03/2013 06:09 AM