Asteroid displays complex gullies
7 December 2012 Last updated at 06:35 GMT
Scientists say they have seen features on Asteroid Vesta that look as though they could have been cut by some sort of fluid flow - possibly liquid water.
The gullies, seen running down the walls of some craters, were pictured by Nasa's Dawn probe.
University of California, Los Angeles, researcher Jennifer Scully described her investigations of the features to our correspondent Jonathan Amos.