Life on Mars:There is more than enough evidence that Mars had water, so we should start looking for a food supply that could have sustained life in the past and could be doing so today, a scientist has argued.
The AAAS meeting heard yet more evidence that liquid water once flowed on Mars. Dr Chris Okubo described work published yesterday in the journal Science on his study of water-based "bleaching" seen in rocks on the Red Planet's surface.
"What is so important about this finding is these chemical reactions are very, very slow. The fact that we can see them from orbit suggests the fluid was in the rock for some time," Dr Okubo told the meeting.
"These areas would be nice protected areas for any biological processes to occur."
Studies of Mars by satellite and surface rover have consistently shown evidence of water, said Dr David Des Marais of Nasa's Ames Research Centre. "We are finding so much evidence for water in so many places we have to come up with [plans] to decide which are the most interesting from the perspective of finding evidence of life. We have to follow the water, but also follow the energy for life, the carbon and other materials needed to build life."
Dr Tori Hoehler, also of Ames, described Mars as a huge chemical "planetary battery" that could provide energy and food. "If we seek out the areas where there is food, we have a greater potential for finding life."
When liquid water flowed on the surface, sunlight would have provided this energy. But as has been seen on earth, bacterial life can draw energy from stones if there is water present, he added.
Ultramafic rocks released hydrogen in the presence of water to support microbial life on earth, and this process could be happening metres under the Martian surface.
