Wed. Jul 28th, 2021

This evenly layered rock photographed by the Mast Camera (Mastcam) on NASAs Curiosity Mars Rover shows a pattern typical of a lake-floor sedimentary deposit not far from where running water entered a lake. Credit: NASA/JPL-Caltech/MSSS
” We used to think that when these layers of clay minerals formed at the bottom of the lake in Gale Crater, they remained that way, maintaining the moment in time they formed for billions of years,” said Tom Bristow, CheMin principal investigator and lead author of the paper at NASAs Ames Research Center in Californias Silicon Valley. “But later salt water broke down these clay minerals in some places– basically resetting the rock record.”
Mars: It Goes on Your Permanent Record
Mars has a bonanza of incredibly ancient rocks and minerals compared with Earth. And with Gale Craters undisturbed layers of rocks, researchers understood it would be an exceptional website to search for proof of the planets history, and potentially life.
Using CheMin, researchers compared samples taken from 2 locations about a quarter-mile apart from a layer of mudstone deposited billions of years back at the bottom of the lake at Gale Crater. Surprisingly, in one location, about half the clay minerals they expected to find were missing out on. Instead, they found mudstones rich with iron oxides– minerals that offer Mars its characteristic rusty red color.
Scientists understood the mudstones sampled were about the same age and started the very same– packed with clays– in both locations studied. So why then, as Curiosity checked out the sedimentary clay deposits along Gale Crater, did spots of clay minerals– and the proof they maintain– “disappear”?
Clays Hold Clues
Minerals are like a time capsule; they offer a record of what the environment resembled at the time they formed. Clay minerals have water in their structure and are evidence that the soils and rocks that contain them entered contact with water at some point.
” Since the minerals we discover on Mars also form in some areas in the world, we can use what we understand about how they form on Earth to inform us about how salted or acidic the waters on ancient Mars were,” said Liz Rampe, CheMin deputy principal detective and co-author at NASAs Johnson Space Center in Houston.
The network of cracks in this Martian rock piece called “Old Soaker” may have formed from the drying of a mud layer more than 3 billion years earlier. Credit: NASA/JPL-Caltech/MSSS
Previous work revealed that while Gale Craters lakes were present and even after they dried, groundwater moved listed below the surface, dissolving and transporting chemicals. After they were deposited and buried, some mudstone pockets experienced different conditions and procedures due to interactions with these waters that altered the mineralogy. This procedure, called “diagenesis,” frequently complicates or erases the soils previous history and writes a brand-new one.
Diagenesis produces an underground environment that can support microbial life. Some extremely unique environments on Earth– in which microbes grow– are understood as “deep biospheres.”
” These are exceptional places to look for proof of ancient life and gauge habitability,” said John Grotzinger, CheMin co-investigator and co-author at the California Institute of Technology, or Caltech, in Pasadena, California. “Even though diagenesis might erase the indications of life in the original lake, it develops the chemical gradients needed to support subsurface life, so we are truly thrilled to have actually found this.”
The Mast Camera (Mastcam) on NASAs Curiosity Mars rover captured this mosaic as it explored the “clay-bearing unit” on Feb. 3, 2019 (Sol 2309). This landscape includes the rocky landmark nicknamed “Knockfarril Hill” (center right) and the edge of Vera Rubin Ridge, which runs along the top of the scene. Credit: NASA/JPL-Caltech/MSSS
Researchers think these results provide more evidence of the effects of Mars climate modification billions of years ago. This info likewise will be utilized by NASAs Mars 2020 Perseverance rover team as they evaluate and choose rock samples for eventual return to Earth.
” Weve discovered something extremely crucial: There are some parts of the Martian rock record that arent so proficient at maintaining evidence of the worlds past and possible life,” stated Ashwin Vasavada, Curiosity task researcher and co-author at NASAs Jet Propulsion Laboratory in Southern California. “The fortunate thing is we discover both close together in Gale Crater, and can use mineralogy to inform which is which.”
Curiosity is in the preliminary stage of investigating the transition to a “sulfate-bearing system,” or rocks believed to have actually formed while Mars environment dried.
Reference: “Brine-driven destruction of clay minerals in Gale crater, Mars” by T. F. Bristow, J. P. Grotzinger, E. B. Rampe, J. Cuadros, S. J. Chipera, G. W. Downs, C. M. Fedo, J. Frydenvang, A. C. McAdam, R. V. Morris, C. N. Achilles, D. F. Blake, N. Castle, P. Craig, D. J. Des Marais, R. T. Downs, R. M. Hazen, D. W. Ming, S. M. Morrison, M. T. Thorpe, A. H. Treiman, V. Tu, D. T. Vaniman, A. S. Yen, R. Gellert, P. R. Mahaffy, R. C. Wiens, A. B. Bryk, K. A. Bennett, V. K. Fox, R. E. Millken, A. A. Fraeman and A. R. Vasavada, 9 July 2021, Science.DOI: 10.1126/ science.abg5449.
The mission is handled by JPL, a division of Caltech, for NASAs Science Mission Directorate, Washington. Coworkers in NASAs Astromaterials Research and Exploration Science Division at Johnson and NASAs Goddard Space Flight Center in Greenbelt, Maryland, also are authors on the paper, as well as other organizations dealing with Curiosity.

A self-portrait of NASAs Curiosity rover taken on Sol 2082 (June 15, 2018). A Martian dust storm has minimized sunlight and presence at the rovers location in Gale Crater. Credit: NASA/JPL-Caltech/MSSS
A new paper enriches scientists understanding of where the rock record destroyed or protected evidence of Mars past and possible signs of ancient life.
Today, Mars is a planet of extremes– its bitterly cold, has high radiation, and is bone-dry. Billions of years back, Mars was home to lake systems that could have sustained microbial life. As the worlds climate changed, one such lake– in Mars Gale Crater– slowly dried out. Scientists have brand-new proof that supersalty water, or salt water, leaked deep through the fractures, in between grains of soil in the parched lake bottom and changed the clay mineral-rich layers underneath.
The findings published in the July 9 edition of the journal Science and led by the team in charge of the Chemistry and Mineralogy, or CheMin, instrument– aboard NASAs Mars Science Laboratory Curiosity rover– aid include to the understanding of where the rock record ruined or protected proof of Mars possible and previous indications of ancient life.

Billions of years ago, Mars was house to lake systems that might have sustained microbial life. As the planets climate altered, one such lake– in Mars Gale Crater– slowly dried out. Rather, they discovered mudstones abundant with iron oxides– minerals that offer Mars its characteristic rusty red color.
The Mast Camera (Mastcam) on NASAs Curiosity Mars rover captured this mosaic as it explored the “clay-bearing unit” on Feb. 3, 2019 (Sol 2309). Researchers think these outcomes use additional evidence of the impacts of Mars climate change billions of years earlier.

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