spacetoday.net: Satellite observations lower population of near Earth objects

Posted: Sun, Oct 2, 2011, 5:49 PM ET (2149 GMT)
WISE spacecraft illustration (NASA)

Observations by a NASA spacecraft have led scientists to conclude that there are fewer near Earth objects (NEOs) than previously thought, lessening the risk of one of them impacting the Earth. The Wide-field Infrared Survey Explorer (WISE) spacecraft detected at least 585 NEOs as it scanned the entire celestial sky twice between January 2010 and February 2011. Planetary scientists used those observations to conclude that there are about 19,500 "mid-sized" NEOs, with diameters between 100 and 1,000 meters, about 45% less than previously thought. The observations also revise the number of large NEOs from 1,000 to 981, with 93% of those having already been discovered, meeting a goal set by Congress in 1998. The reduction in the estimated population of NEOs means that the risk of an impact is corresponding reduced.