NASA's rover Opportunity, the second Mars probe, has found evidences of clays formed in waters with acidity levels suitable for life.
The solar-powered Opportunity, which landed on Mars in January 2004 with its twin rover, Spirit, which succumbed to the harsh Martian environment three years ago, had both found rocks altered by highly acidic water.
Even though there are microbes that thrive in acidic environment on Earth, scientists suspect the chemical building blocks for life need more neutral conditions to evolve into life.
Cornell University's Steve Squyres, lead scientist for the Opportunity and Spirit missions, in a conference call to reporters on Friday explained how hard acidic environment to life.
"The tough thing about an acid environment is that it's very, very hard, we believe, to get pre-biotic chemistry, the kind of chemistry that can lead to the origin of life," he said. "What's exciting about this discovery is that it points to a neutral pH at a time very, very early in Martian history."
"What we have here is a very different chemistry. This is water you can drink," Squyres continued. "This is the most powerful evidence for neutral (non-acidic) chemistry water that has been found by Opportunity," he added.
Opportunity took three years to reach the rim of a large impact basin called Endeavour Crater, where it examined, among other objects, a small rock called Esperance.
It took seven tries before Opportunity got itself positioned properly to scratch the rock's surface and see what lies beneath. Unlike NASA's follow-on Mars rover Curiosity, which landed on the opposite side of Mars in August, Opportunity has no drill or onboard chemistry lab to obtain and analyze samples.
Instead, it uses its instruments to determine basic mineralogy. Esperance, scientists determined, contains aluminum-rich clays, a telltale sign that neutral water flowed through the rock.
Likewise, Curiosity's first analysis of powder drilled from an ancient mudstone showed signs of neutral water, plus elements needed to support microbial life. Results from the rover's second sample analysis are pending.
