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Conflicting reports abound from the Red Planet

A plethora of data from craft in orbit and on the ground are causing some confusion on the issues of past water, and the possibility of past life, on Mars.

The HiRISE camera on Mars Reconnaissance Orbiter recently snapped photos of a dry lakebed that might have been home to life on Mars. The ancient lakebed lies inside Mars’ Holden Crater.

From left: The Opportunity rover discovered lethally high concentrations of minerals in this layer of Victoria Crater; Mars Reconnaissance Orbiter spied mineral-rich clay in a dry lakebed that might have harbored past life; A gravel slide probably carved this gully, not recently flowing water. (NASA)

The lakebed contains minerals that formed in the presence of water that marks “potentially habitable environments,” said Alfred McEwen of The University of Arizona.

“This would be an excellent place to send a rover or sample-return mission to make major advances in understanding if Mars supported life,” he said.

However, other scientists have interpreted observations from the Martian surface taken by the Opportunity rover to show that early water at its landing site held such high concentrations of dissolved minerals that microbes could not develop or survive there.

“Not all water is fit to drink,” said Harvard biologist Andrew Knoll, a member of the rover science team.

Opportunity studied a band of rocks around the wall of a crater. Studies indicated the crater wall was the at the top of an underground water table.

The results of experiments with simulated Martian conditions and computer modeling are making the chances for past life to have existed in Mars’ Meridiani Planum look slimmer.

“This tightens the noose on the possibility of life,” Knoll said. “Life at the Martian surface would have been very challenging for the last four billion years. The best hopes for a story of life on Mars are at environments we haven’t studied yet — older ones, subsurface ones.”

The upcoming missions Phoenix and Mars Science Laboratory will study sites known to have held water to see if they have conditions suitable for life. Later missions will probe the suitable sites for evidence of life, said Charles Elachi, director of NASA’s Jet Propulsion Lab.

While these scientists are studying what might have been in the water on Mars, others are proving, reluctantly, that 2006 claims of recent water flow on Mars based on images from Mars Global Surveyor might be wrong. Two years ago, scientists said they thought bright spots seen in Martian gullies indicated that liquid water must have flowed there within the past decade.

Computer modeling of the gullies by Jon Pelletier at The University of Arizona shows the gullies’ structure is a better match for a dry, granular rock slide than for liquid water. “I was surprised,” he said. “I started out thinking we were going to prove it’s liquid water.” RJ