This enhanced Perseverance Mastcam-Z color photomosaic shows a bulge near Jezero Crater, informally named “Kodiak” by the rover team. Courtesy: NASA/JPL-Caltech/ASU/MSSS; edited by Jim Bell/ASU
Rock samples from Jezero Crater analyzed by NASA’s Perseverance rover show evidence of liquid water and signatures that may be organic compounds.
Analyzes of multiple rocks found at the bottom of Jezero Crater on Mars, where the Perseverance rover landed in 2020, have revealed a significant interaction between the rocks and liquid water. Evidence of the presence of organic compounds has also been found in these rocks.
“I hope that one day these samples can be returned to Earth so that we can study whether conditions were suitable for life in the early history of Mars.” — Professor Mark Sefton
Organic compounds (chemical compounds with carbon-hydrogen bonds) can be created by non-biological processes, so the mere existence of these compounds is not direct evidence of life. To determine this definitively, a future mission will be needed to return the samples to Earth.
Led by Caltech researchers and conducted by an international team including researchers from Imperial College London, the study was published Nov. 23 in the journal Science.
Professor Mark Sefton, from Imperial College London’s Faculty of Science and Engineering, is a member of the science team that participated in rover operations on Mars and considered the implications of the results. He said: “I hope that one day these samples can be returned to Earth so that we can look at the evidence for water and possible organic matter and investigate whether conditions were suitable for life in the early history of Mars.”
Moving water
Perseverance has already found organic compounds in the Jezero Delta. Deltas are fan-shaped geological formations created at the intersection of a river and a lake on the rim of a crater.
Mission scientists were particularly interested in the Jezero Delta because such formations can preserve microorganisms. Deltas are created when a river transporting fine-grained sediments enters a deeper, slower-moving body of water. As river water spreads, it slows down sharply, depositing the sediments it carries and capturing and preserving any microorganisms that may exist in the water.
However, the bottom of the crater, where the rover landed for safety reasons before traveling to the delta, was more of a mystery. In lakebeds, researchers expected to find sedimentary rocks as water deposited layer after layer of sediment. However, when the rover touched down there, some researchers were surprised to find igneous rocks (cooled magma) at the bottom of the crater with minerals in them, which recorded not only magmatic processes, but also significant contact with water.
These minerals, such as carbonates and salts, require water to circulate within the igneous rocks, carving out niches and depositing dissolved minerals in various areas such as cavities and cracks. In some places, the data show evidence of organic matter in these potentially habitable niches.
Discovered by SHERLOC
Minerals and co-located possible organic compounds were detected using SHERLOC or the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals tool.
Mounted on the rover’s robotic arm, SHERLOC is equipped with a number of instruments, including a Raman spectrometer that uses a specific type of fluorescence to look for organic compounds and also see how they are distributed in a given material, providing insight into how they were preserved at that place.
Bethany Elman, co-author of the paper, professor of planetary sciences and associate director of the Keck Institute for Space Studies, said, “The microscopic compositional imaging capabilities of SHERLOC have really opened up our ability to decipher the temporal order of Mars’ past environments.”
As the rover rolled toward the delta, it took several samples of the water-altered igneous rocks and stored them for a possible future sample return mission. The samples will have to be returned to Earth and examined in laboratories with advanced instruments to definitively determine the presence and type of organic matter and whether it has anything to do with life.
Reference: “Aqueous Alteration Processes at Jezero Crater, Mars−Implications for Organic Geochemistry” by Eva L. Scheller, Joseph Razzel Hollis, Emily L. Cardarelli, Andrew Steele, Luther W. Beagle, Rohit Bhartia, Pamela Conrad, Kyle Uckert, Sunanda Sharma, Bethany L. Ehlmann, William J. Abbey, Sanford A. Asher, Kathleen C. Benison, Eve L. Berger, Olivier Beyssac, Benjamin L. Bleefeld, Tanja Bosak, Adrian J. Brown, Aaron S. Burton, Sergei V Bykov, Ed Klutis, Alberto G. Firen, Lauren DeFlores, Kenneth A. Farley, Deidra M. Fay, Teresa Fornaro, Alison K. Fox, Mark Fries, Kieran Hickman-Lewis, William F. Hough, Joshua E. Huggett, Samara Imbea, Ryan S. Jakubek, Linda K. Kah, Peter Kelemen, Megan R. Kennedy, Tanya Kizowski, Karina Lee, Yang Liu, Lucia Mandon, Frances M. McCubbin, Kelsey R. Moore, Brian E. Nixon, Jorge I .Núñez, Carolina Rodríguez Sánchez-Vajamonde, Ryan D. Ropell, Mitchell Schulte, Mark A. Sefton, Shiv K. Sharma, Sandra Silleström, Svetlana Shkolyar, David L. Schuster, J. Justin I. Simon, Rebecca J. Smith, Kathryn M. Stack, Kim Stedman, Benjamin P. Weiss, Alyssa Werinsky, Amy J. Williams, Roger S. Wiens, Kenneth H. Williford, Kathryn Winchell, Brittan Wagsland, Anastasia Yanchilina, Rachel Yingling, and Maria-Paz Zorzano, 23 Nov 2022, Science.DOI: 10.1126/science.abo5204
The research was funded by NASA, the European Research Council, the Swedish National Space Agency and the UK Space Agency.
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