Rocks seen by NASA's Opportunity rover and Curiosity rover on two different parts of Mars.
NASA is reporting that an analysis of a rock powder sample collected by the Curiosity rover suggests that ancient Mars could have supported living microbes.
The sample contained traces of sulfur, nitrogen, hydrogen, oxygen, phosphorus, and carbon -- key chemical ingredients for life.
For astronomers, the news constitutes the latest clue in their pursuit of a scientific holy grail: Answering the big question about whether life ever existed on the Red Planet. Their challenge until now has been to confirm whether the Martian atmosphere could have supported a habitable environment. The preliminary evidence now suggests the answer is yes, with the rock samples pointing to evidence that conditions on Mars were once favorable for life. A couple of particularly intriguing clues: The presence of clay as well as the absence of "abundant salt" point to the likely existence of an ancient environment where there was fresh water, according to NASA.
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"The range of chemical ingredients we have identified in the sample is impressive, and it suggests pairings such as sulfates and sulfides that indicate a possible chemical energy source for micro-organisms," Paul Mahaffy, principal investigator of the SAM suite of instruments at NASA's Goddard Space Flight Center, said in a statement.
Curiosity drilled the powder from a sedimentary rock near an ancient stream bed in Gale Crater on Mars last month.
False-color map of the region inside Gale Crater where NASA's Curiosity rover landed on August 5, 2012. The rover drilled its first sample at the "John Klein" rock.
In analyzing and comparing rock samples, NASA said that drill powder taken from the "John Klein" bedrock indicated the existence of a "mildly alkaline pH environment" where fresh water would have existed. A lot
of water, or in NASA parlance: "The John Klein mineralogy suggests a lacustrine (lake bed) environment with high water activity."
Side-by-side X-ray comparison of two different samples collected from the Martian surface by NASA's Curiosity rover.