Water on Mars. Life ????

The big question is back: could life exist on Mars? Photographs taken from orbit suggest that water may have flowed on the surface of Mars in the very recent past – or may still do so – raising yet again the possibility of life on Mars.

Speculation about water on Mars is not new. What’s new is the evidence of its recent traces. The images taken by NASA’s Mars Global Surveyor show apparently recent changes in surface features that provide the strongest evidence yet that water even now sometimes flows on the dusty, frigid world.

The Global Surveyor spotted gullies and trenches that seemed to be geologically young and carved by fast – moving water coursing down cliffs and crater walls.

Scientists at the San Diego based Malin Space Systems, who operate a camera abroad the spacecraft, decided top retake photos of thousands of gullies. Two gullies that were originally photographed in 1999 and 2001 and re-imaged in 2004 and 2005 showed changes which could have been caused by water flowing down crater walls. In both cases, scientists found bright, light – coloured deposits in the gullies that weren’t present in the original photos.

They concluded the deposits possibly mud, salt or frost were left there when water recently cascaded through the channels.

Oded Aharonson, an assistant professor of planetary science at the California Institute of Technology, said that while the interpretation of recent water activity on Mars was “compelling,” it’s just one possible explanation. Aharonson added that further study is needed to determine whether the deposit could have been left there by the flow of dust rather than water.