Space Rock Misses Mars, Barely

An asteroid once thought to be on a collision course with Mars passed the Red Planet today without incident.
Astronomers first estimated that asteroid 2007 WD5 had as high as a 3.6 percent chance of striking the planet. Newer observations kept lowering the odds for the 164-foot space rock until Jan. 9, when NASA’s Near-Earth Object (NEO) program office effectively ruled out chances of an impact.
“Mars sees these kinds of near-miss encounters every ten or twenty years, but the impact rate for asteroids this size is about once in a thousand years,” said Steve Chesley, an astronomer at the Jet Propulsion Lab in Pasadena, California.