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NASA’s Wide-field Infrared Survey Explorer (WISE), an infrared space telescope, mapped the asteroid population near Earth and elsewhere in the solar system. The asteroid survey, which NASA says is the most accurate ever performed, also lowered the estimated number of giant near-Earth asteroids — space rocks the size of a mountain or larger — from 1,000 to 981, with about 911 of those already known, researchers said.
“The risk of a really large asteroid impacting the Earth before we could find and warn of it has been substantially reduced,” said Tim Spahr, the director of the Minor Planet Center at the Harvard Smithsonian Center for Astrophysics in Cambridge, Mass.
Getting WISE to asteroids
By the end of the WISE telescope’s extended mission, called NEOWISE, last year, astronomers had found 90 percent of the largest asteroids near our planet, NASA scientists said, which met the goal that was set forth by Congress in 1998.
The WISE space telescope mapped the entire sky twice between January 2010 and February 2011, surveying near-Earth asteroids, brown dwarfs, galaxies and other deep space objects in infrared light. As part of its near-Earth asteroid search, the space observatory scanned for space rocks that orbited within 120 million miles (195 million kilometers) of the sun. The Earth is about 93 million miles (150 million km) from the sun. [Video: Killer Asteroids, We’re WISE to You .Now
Source: Space.com
http://www.space.com/13132-potentially-killer-asteroids-earth-nasa.html
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