Washington, Feb 16 : New discoveries by NASA's Opportunity rover has led scientists to suggest that life might have been thwarted from developing in the early history of Mars because of high concentrations of dissolved minerals in the wet environment of the Red Planet.
Experiments with simulated Martian conditions and computer modeling are helping researchers refine earlier assessments of whether the long-ago conditions in the Meridiani area studied by Opportunity would have been hospitable to microbes.
According to Andrew Knoll, a member of the rover science team, "At first, we focused on acidity, because the environment would have been very acidic."
"Now, we also appreciate the high salinity of the water when it left behind the minerals Opportunity found. This tightens the noose on the possibility of life," he added.
Conditions may have been more hospitable earlier, with water less brackish, but later conditions at Meridiani and elsewhere on the surface of Mars appear to have been less hospitable.
"Life at the Martian surface would have been very challenging for the last 4 billion years," said Knoll.
NASA's current rovers and orbiters at Mars pursue the agency's "follow the water" theme for Mars exploration. They decipher the roles and fate of water on a planet whose most striking difference from Earth is a scarcity of water.
"Our next missions, Phoenix and Mars Science Laboratory, mark a transition from water to habitability - assessing whether sites where there's been water have had conditions suited to life," said Charles Elachi, director of NASA's Jet Propulsion Laboratory, Pasadena, California.
"Where conditions were habitable, later missions may look for evidence of life," he added.