01 November 2009

Asteroid Explodes in the Atmosphere: It reveals gaps in planetary defense systems

Yet further confirmation that we need increased attention to short-term warning for small threats:
From: http://news.softpedia.com/news/Asteroids-Explodes-in-the-Atmosphere-125310.shtml
On Friday, the American space agency released a full report, in which it gave details about the asteroid that exploded high in the planet's atmosphere on October 8, in the skies over Indonesia. According to NASA, the asteroid blew up with the strength of 50,000 tons of TNT, an explosion about three times more powerful than the one that destroyed the Japanese city of Hiroshima at the end of the World War II. The recent explosion is therefore one of the largest ever recorded, the same source reveals.
Experts estimate that the asteroid was at least ten meters across, and that the extremely energetic explosion took place at an altitude of about 15 to 20 kilometers. The conclusion belongs to Peter Brown, who is an astronomer at the University of Western Ontario (UWO), in Canada, and also a member of the team that conducted the analysis of the rogue object. There were neither casualties at ground level, nor any material damages following the explosion.
The new event, astronomers highlight, should draw the governments' attention to the fact that the Earth's defense systems are not even remotely foolproof. Experts argue that an asteroid that is at least 20 meters across can possibly cause a lot of damage to the ground, but say that observatories equipped to identify such small space rocks are very few. “If you want to find the smallest objects you have to build more, larger telescopes. A survey that finds all of the 20-meter objects will cost probably multiple billions of dollars,” Minor Planet Center Director Tim Spahr says.
The expert and UWO colleague Elizabeth Silber estimated the immense energy of the explosion from infrasound waves that were collected halfway around the world by a listening network, specialized in detecting hidden nuclear explosions. The two astronomers say that this is not a rare event. Such a small asteroid hits the Earth about once every ten years, which is almost continuous by cosmic standards.
The White House needs to develop a defense policy against these space rocks by no later than October 2010. The deadline was imposed by the Congress. It is expected that the decision will be communicated through a National Research Council report, due to be released by the end of 2009, NewScientist informs.