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Mars rover finds conditions once suited for life

March 13, 2013
Courtesy of NASA
and World Science staff

An anal­y­sis of a rock sam­ple col­lect­ed by NASA’s Cu­ri­os­ity rov­er in­di­cates an­cient Mars could have sup­ported mi­crobes.

Sci­en­tists iden­ti­fied some of the key chem­i­cal in­gre­di­ents for life in the pow­der Cu­ri­os­ity drilled out of a sed­i­men­ta­ry rock near an an­cient stream bed in Gale Crat­er on the Red Plan­et last month. 

“A fun­da­men­tal ques­tion for this mis­sion is wheth­er Mars could have sup­ported a hab­it­a­ble en­vi­ron­ment,” said Mi­chael Mey­er, lead sci­ent­ist for NASA’s Mars Ex­plora­t­ion Pro­gram at the agen­cy’s head­quar­ters in Wash­ing­ton. “From what we know now, the an­swer is yes.”

Rocks of the "Sheepbed" unit in Yel­low­knife Bay, in Gale Crat­er, as seen by Cu­ri­os­i­ty. (Im­age cred­it: NA­SA/JPL-Caltech/Cornell/MSSS)


Clues to this en­vi­ron­ment, the re­search­ers said, come from the rov­er’s Sam­ple Anal­y­sis at Mars and Chem­is­try and Min­er­al­o­gy in­stru­ments. 

Their da­ta in­di­cate the Yel­low­knife Bay ar­ea the rov­er is ex­plor­ing was the end of an an­cient riv­er sys­tem or an in­ter­mit­tently wet lake bed that could have pro­vid­ed chem­i­cal en­er­gy and oth­er fa­vor­a­ble con­di­tions for mi­crobes, they added. The rock is made up of a fine-grained “mud­stone” con­tain­ing clay min­er­als, sul­fate min­er­als and oth­er chem­i­cals. 

This an­cient wet en­vi­ron­ment, un­like some oth­ers on Mars, was not harshly acid­ic or ex­tremely salty or cor­rod­ing, in­vest­i­gat­ors said.

The patch of bed­rock where Cu­ri­os­ity drilled for its first sam­ple lies in an an­cient net­work of stream chan­nels de­scend­ing from the rim of Gale Crat­er, the re­search­er said. The bed­rock al­so is fine-grained mud­stone and shows ev­i­dence of mul­ti­ple pe­ri­ods of wet con­di­tions.

Cu­ri­os­ity’s drill col­lect­ed the sam­ple at a site just a few hun­dred yards or meters away from where the rov­er ear­li­er found an an­cient streambed last Sep­tem­ber. “Clay min­er­als make up at least 20 per­cent of the com­po­si­tion of this sam­ple,” said Da­vid Blake, prin­ci­pal in­ves­ti­ga­tor for the CheMin in­stru­ment at NASA’s Ames Re­search Cen­ter in Mof­fett Field, Ca­lif.

These min­er­als come from a chem­i­cal re­ac­tion of rel­a­tively fresh wa­ter with “ig­neous” min­er­als, which are formed by so­lidifica­t­ion from a mol­ten state, and which in­clude ol­i­vine, he added.

“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,” added Paul Ma­haffy, prin­ci­pal in­ves­ti­ga­tor of the SAM suite of in­stru­ments at NASA’s God­dard Space Flight Cen­ter in Green­belt, Md.

This sur­pris­ing mix­ture of chem­i­cals was first hinted at when the drill cut­tings were re­vealed to be gray rath­er than red, the re­search­ers said.

“We have char­ac­ter­ized a very an­cient, but strangely new ‘gray Mars’ where con­di­tions once were fa­vor­a­ble for life,” said John Grotzinger, Mars Sci­ence Lab­o­r­a­to­ry proj­ect sci­ent­ist at the Ca­lifornia In­sti­tute of Tech­nol­o­gy in Pas­a­de­na, Ca­lif. “We feel there are many more ex­cit­ing dis­cov­er­ies ahead of us.”

Sci­en­tists plan to work with Cu­ri­os­ity in the Yel­low­knife Bay ar­ea for many more weeks be­fore be­gin­ning a long drive to Gale Crat­er’s cen­tral mound, Mount Sharp. In­ves­ti­gat­ing the stack of lay­ers ex­posed on Mount Sharp, where clay min­er­als and sul­fate min­er­als have been iden­ti­fied from or­bit, may add in­forma­t­ion about the dura­t­ion and di­vers­ity of hab­it­a­ble con­di­tions, they said.

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An analysis of a rock sample collected by NASA’s Curiosity rover shows ancient Mars could have supported living microbes, researchers with the space agency say. Scientists identified some of the key chemical ingredients for life in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater on the Red Planet last month. “A fundamental question for this mission is whether Mars could have supported a habitable environment,” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington. “From what we know now, the answer is yes.” Clues to this habitable environment, the researchers said, come from the rover’s Sample Analysis at Mars and Chemistry and Mineralogy instruments. Their data indicate the Yellowknife Bay area the rover is exploring was the end of an ancient river system or an intermittently wet lake bed that could have provided chemical energy and other favorable conditions for microbes, they added. The rock is made up of a fine-grained “mudstone” containing clay minerals, sulfate minerals and other chemicals. This ancient wet environment, unlike some others on Mars, was not harshly acidic or extremely salty or corroding. The patch of bedrock where Curiosity drilled for its first sample lies in an ancient network of stream channels descending from the rim of Gale Crater, the researcher said. The bedrock also is fine-grained mudstone and shows evidence of multiple periods of wet conditions. Curiosity’s drill collected the sample at a site just a few hundred yards away from where the rover earlier found an ancient streambed in September 2012. “Clay minerals make up at least 20 percent of the composition of this sample,” said David Blake, principal investigator for the CheMin instrument at NASA’s Ames Research Center in Moffett Field, Calif. These minerals come from a chemical reaction of relatively fresh water with “igneous” minerals, which are formed by solidification from a molten state, and which include olivine, he added. “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,” added Paul Mahaffy, principal investigator of the SAM suite of instruments at NASA’s Goddard Space Flight Center in Greenbelt, Md. This surprising mixture of chemicals was first hinted at when the drill cuttings were revealed to be gray rather than red, the researchers said. “We have characterized a very ancient, but strangely new ‘gray Mars’ where conditions once were favorable for life,” said John Grotzinger, Mars Science Laboratory project scientist at the California Institute of Technology in Pasadena, Calif. “Curiosity is on a mission of discovery and exploration, and as a team we feel there are many more exciting discoveries ahead of us in the months and years to come.” Scientists plan to work with Curiosity in the “Yellowknife Bay” area for many more weeks before beginning a long drive to Gale Crater’s central mound, Mount Sharp. Investigating the stack of layers exposed on Mount Sharp, where clay minerals and sulfate minerals have been identified from orbit, may add information about the duration and diversity of habitable conditions.