After just six months on Mars, Curiosity looks to have taken a significant step towards fulfilling its primary science mission: to determine whether conditions on the planet once provided a suitable environment in which life might have arisen.
Despite recently suffering a serious computer glitch – of which more later – Curiosity’s initial analysis of cuttings gathered from inside bedrock dubbed “John Klein”, so named in honour of the late John W. Klein, MSL’s former Deputy Project Manager, and which is located in the “Yellowknife Bay” region of Gale Crater, reveals very strong evidence that ancient Mars could have supported living microbes.
Commenting on the findings, Michael Meyer, lead scientist for NASA’s Mars Exploration Programme, said, “A fundamental question for this mission is whether Mars could have supported a habitable environment. From what we know now, the answer is yes.”
The initial findings came via the rover’s Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instruments, which each received a portion of the rock cuttings gathered from within “John Klein” on Sol 182 (February 8th / 9th). The deliveries of the samples took place on Sols 195 (February 22nd) and 196 (February 23rd) respectively, the delay between sample gathering and delivery being down to a combination of the need to “clean” the sample holding and transfer elements of dill bit and concerns over the long-term status of a filter in part of the turret-mounted sample handling mechanism (see Getting the scoop on drilling).
The area of “Yellowknife Bay” sits at the end of what mission scientists believe to be an ancient river system, and which may have been a part of a larger lake bed in planet’s ancient past. During the drive from Bradbury Landing, where it arrived on Mars in August 2012, Curiosity has come across strong evidence for liquid having once flowed freely through the region. Rock formations commonly associated with stream and river beds have been found and imaged, and the “Yellowknife Bay” area itself bears all the hallmarks of having been formed as a result of material being carried in free-flowing liquid – most likely water. These findings have supported evidence from orbit, where images taken by various spacecraft have long pointed to large parts – if not all – of Gale Crater having been subjected to aqueous activity in the distant past. This evidence includes a broad alluvial fan of water-deposited materials located close to the landing area planned for the rover, and regarded as a valuable back-up science target should post-landing issues with the rover prevent it from undertaking the long trek up onto “Mount Sharp”.
The “John Klein” bedrock itself shows strong evidence on its surface for having been formed by aqueous activity spanning numerous wet periods in the planet’s history. However, this is not what has excited scientists – evidence for water having flowed freely on Mars has been found right across the planet, both from orbit and on the ground. During their explorations of Mars, for example, both of the Mars Exploration Rovers – Spirit (before its demise) and Opportunity – came across rock formations which had most likely been formed in the presence of liquid water.
What makes the findings returned from “Yellowknife Bay” exciting for scientists is that previously, those areas of rock thought to have been formed as a result aqueous activity also showed strong signs that the water was likely to have been highly acidic and had what is referred to as a “low energy gradient”, both of which would have made the chances of life arising within it exceptionally challenging.
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