Asteroid 24 Themis, a 100 mile wide lone rock between Mars and Jupiter in the asteroid belt. But even more important, scientist found organic molecules in the scattered lightwaves bounching off the asteroid.
Hydrogen and oxygen and bits of water are locked in clay has been the theory up until 24 Themis appears to have proven right.
For more details, please the artilces from any of the links presented below.
REf, BBC April 29, 2010 (http://news.bbc.co.uk/2/hi/science_and_environment/10090128.stm).
Comcast, April 29, 2010. by Seth Borenstein (http://www.comcast.net/articles/news-science/20100428/US.SCI.Icy.Asteroid/).