About 1,000 asteroids big enough to cause catastrophic damage if they hit Earth are orbiting relatively nearby, a NASA survey shows. In a project known as Spaceguard, the U.S. space agency was ordered by Congress in 1998 to find 90% of objects near Earth that are one kilometre in diameter or larger. The survey is now complete, with 93% of the objects accounted for, said astronomer Amy Mainzer of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Using NASA’s recently retired Wide-field Infrared Survey Explorer (WISE) telescope, scientists also found about 20,500 smaller asteroids near Earth. Previous studies estimated there were 36,000 to 100,000 of these objects, which have a diameter of about 100 metres. “They could still pack quite a punch,” Ms. Mainzer said. But a major asteroid strike could and has happened. Canada Dot Com
1,000 Dangerous Asteroids Orbiting Near Earth
December 11, 2011 By