spacetoday.net: Water ice found on asteroid

Posted: Thu, Apr 29, 2010, 6:50 AM ET (1050 GMT)
Asteroids 24 Themis illustration (UCF)

Astronomers announced Wednesday that they have detected water ice on the surface of an asteroid for the first time, a discovery that may provide clues to the origins of the Earth's oceans. Infrared observations of the asteroid 24 Themis detected water ice and organic molecules evenly distributed across the asteroid's surface, according to a study published in the current issue of the journal Nature. The discovery is surprising because ice should not be stable on a main belt asteroid like Themis because it is warm enough for the ice to vaporize over short periods of time. Scientists speculate that the ice might be preserved just below the surface. The discovery suggests that impacting asteroids could have been a source of water early in the history of the Earth, providing the water that filled the Earth's oceans.