Research sheds new light on asteroid disaster

An asteroid that exploded over Siberia a century ago, leaving 800 square miles of scorched or blown down trees, wasn't nearly as large as previously thought, a researcher concludes, suggesting a greater danger for Earth.

According to supercomputer simulations by Sandia National Laboratories physicist Mark Boslough, the asteroid that destroyed the forest at Tunguska in Siberia in June 1908 had a blast force equivalent to one-quarter to one-third of the 10- to 20-megaton range scientists previously estimated.

Better understanding of what happened at Tunguska will allow for better estimates of risk that would allow policymakers to decide whether to try to deflect an asteroid or evacuate people in its path, he said.

"It's not clear whether a 10-megaton asteroid is more damaging than a Hurricane Katrina," Boslough said. "We can more accurately predict the location of an impact and its time better than we can a hurricane, so you really could get people out of there if it's below a certain threshold."

http://edition.cnn.com/2008/TECH/space/01/29/asteroid.recalculated.ap/index.html