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1. OVERVIEW OF THE BEDROCK GEOCHEMISTRY AND MINERALOGY OBSERVED BY SUPERCAM DURING PERSEVERANCE'S DELTA FRONT CAMPAIGN

Author

Dehouck, Erwin, Forni, Olivier, Quantin-Nataf, Cathy, Beck, Pierre, Mangold, Nicolas, Royer, Clément, Clavé, Elise, Beyssac, Olivier, Johnson, Jeffrey, Mandon, Lucia, Poulet, François, Le Mouélic, Stéphane, Caravaca, Gwénaël, Kalucha, Hemani, Gibbons, Erin, Dromart, Gilles, Gasda, Patrick, Meslin, Pierre-Yves, Schroeder, Susanne, Udry, Arya, Anderson, Ryan B., Clegg, Samuel, Cousin, Agnès, Gabriel, Travis, Lasue, Jérémie, Fouchet, Thierry, Pilleri, Paolo, Pilorget, Cédric, Hurowitz, Joel, Núñez, Jorge, Williams, Amy, Russell, Patrick, Simon, Justin I., Maurice, Sylvestre, Wiens, Roger, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, Centre d'Etudes Lasers Intenses et Applications (CELIA), Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), McGill University = Université McGill [Montréal, Canada], Los Alamos National Laboratory (LANL), Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), University of Nevada [Las Vegas] (WGU Nevada), US Geological Survey [Flagstaff], United States Geological Survey [Reston] (USGS), United States Geological Survey (USGS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Stony Brook University [SUNY] (SBU), State University of New York (SUNY), Department of Geological Sciences [Gainesville] (UF|Geological), University of Florida [Gainesville] (UF), Department of Earth, Planetary and Space Sciences [Los Angeles] (EPSS), University of California [Los Angeles] (UCLA), University of California (UC)-University of California (UC), NASA Johnson Space Center (JSC), NASA, and Lunar and Planetary Institute

Subjects
jezero crater, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, [SDU]Sciences of the Universe [physics], [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy, Mars 2020, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, mars, delta front, geochemistry
Abstract

International audience; In February 2021, the Perseverance rover landed in Jezero crater, Mars. The crater floor was found to be composed of lava flows and cumulate rocks [1-5]. These magmatic rocks appear to have undergone some limited aqueous alteration; however, it is not clear whether this alteration is related to the lacustrine phase of the crater [1,3,6,7].After completing its exploration of the crater floor, Perseverance reached the foot of the Jezero western fan in late April 2022 (sol ~422). Long-distance images acquired earlier in the mission had already confirmed the deltaic nature of the fan [8], which had long been suspected from orbital observations [9,10]. Between April and December 2022, Perseverance investigated the basal layers of the delta at two locations named Hawksbill Gap and Cape Nukshak, which are ~400 m apart [11]. Here, we present an overview of the geo-chemistry and mineralogy of the delta rocks as observed by SuperCam, and show that these rocks record a diver-sity of past aqueous alteration environments.

Published
2023

2. Compositionally and density stratified igneous terrain in Jezero crater, Mars

Author

Wiens, Roger C., Udry, Arya, Beyssac, Olivier, Quantin-Nataf, Cathy, Mangold, Nicolas, Cousin, Agnès, Mandon, Lucia, Bosak, Tanja, Forni, Olivier, McLennan, Scott M., Sautter, Violaine, Brown, Adrian, Benzerara, Karim, Johnson, Jeffrey R., Mayhew, Lisa, Maurice, Sylvestre, Anderson, Ryan B., Clegg, Samuel M., Crumpler, Larry, Gabriel, Travis S. J., Gasda, Patrick, Hall, James, Horgan, Briony H. N., Kah, Linda, Legett, Carey, Madariaga, Juan Manuel, Meslin, Pierre-Yves, Ollila, Ann M., Poulet, Francois, Royer, Clement, Sharma, Shiv K., Siljeström, Sandra, Simon, Justin I., Acosta-Maeda, Tayro E., Alvarez-Llamas, Cesar, Angel, S. Michael, Arana, Gorka, Beck, Pierre, Bernard, Sylvain, Bertrand, Tanguy, Bousquet, Bruno, Castro, Kepa, Chide, Baptiste, Clavé, Elise, Cloutis, Ed, Connell, Stephanie, Dehouck, Erwin, Dromart, Gilles, Fischer, Woodward, Fouchet, Thierry, Francis, Raymond, Frydenvang, Jens, Gasnault, Olivier, Gibbons, Erin, Gupta, Sanjeev, Hausrath, Elisabeth M., Jacob, Xavier, Kalucha, Hemani, Kelly, Evan, Knutsen, Elise, Lanza, Nina, Laserna, Javier, Lasue, Jeremie, Le Mouélic, Stéphane, Leveille, Richard, Lopez Reyes, Guillermo, Lorenz, Ralph, Manrique, Jose Antonio, Martinez-Frias, Jesus, McConnochie, Tim, Melikechi, Noureddine, Mimoun, David, Montmessin, Franck, Moros, Javier, Murdoch, Naomi, Pilleri, Paolo, Pilorget, Cedric, Pinet, Patrick, Rapin, William, Rull, Fernando, Schröder, Susanne, Shuster, David L., Smith, Rebecca J., Stott, Alexander E., Tarnas, Jesse, Turenne, Nathalie, Veneranda, Marco, Vogt, David S., Weiss, Benjamin P., Willis, Peter, Stack, Kathryn M., Williford, Kenneth H., Farley, Kenneth A., Los Alamos National Laboratory (LANL), University of Nevada [Las Vegas] (WGU Nevada), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS), Massachusetts Institute of Technology (MIT), Stony Brook University [SUNY] (SBU), State University of New York (SUNY), Plancius Research LLC, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Department of Geological Sciences [Boulder], University of Colorado [Boulder], Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), New Mexico Museum of Natural History and Science (NMMNHS), Department of Earth, Atmospheric, and Planetary Sciences [West Lafayette] (EAPS), Purdue University [West Lafayette], Department of Earth and Planetary Sciences [Knoxville], The University of Tennessee [Knoxville], University of the Basque Country/Euskal Herriko Unibertsitatea (UPV/EHU), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), University of Hawai'i [Honolulu] (UH), RISE Research Institutes of Sweden, Center for Isotope Cosmochemistry and Geochronology, NASA Johnson Space, Universidad de Málaga [Málaga] = University of Málaga [Málaga], Department of Chemistry and Biochemistry [Columbia, South Carolina], University of South Carolina [Columbia], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Centre d'Etudes Lasers Intenses et Applications (CELIA), Université de Bordeaux (UB)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), University of Winnipeg, California Institute of Technology (CALTECH), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), University of Copenhagen = Københavns Universitet (UCPH), McGill University = Université McGill [Montréal, Canada], Department of Earth Science and Engineering [Imperial College London], Imperial College London, Institut de mécanique des fluides de Toulouse (IMFT), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad de Valladolid [Valladolid] (UVa), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), University of Maryland [College Park], University of Maryland System, Department of Physics and Applied Physics [Lowell], University of Massachusetts [Lowell] (UMass Lowell), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS), Institut Supérieur de l'Aéronautique et de l'Espace (ISAE-SUPAERO), DLR Institute of Optical Sensor Systems, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Department of Earth and Planetary Science [UC Berkeley] (EPS), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)

Subjects
emplacement, LIBS, shergottites, Multidisciplinary, Mars2020, Mars, Perseverance, system, rocks, reflectance spectra, Vis, in-situ, SuperCam, [SDU]Sciences of the Universe [physics], rover, IR, origin, surface, identification, Raman, olivine
Abstract

Before Perseverance, Jezero crater's floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification.The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which also express olivine disequilibrium. Alteration materials including carbonates, sulfates, perchlorates, hydrated silicates, and iron oxides are pervasive but low in abundance, suggesting relatively brief lacustrine conditions. Orbital observations link the Jezero floor lithology to the broader Nili-Syrtis region, suggesting that density-driven compositional stratification is a regional characteristic. Funding was provided by the following sources: NASA's Mars exploration program, including contracts NNH15AZ24I and NNH13ZDA018O to LANL. LANL LDRD code XWHW contributed to calibrations. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). NASA RSSPS grants supported J.I.S., grantnumber 80NSSC20K0239 supported L. Hausrath, grant number 80NSSC20K0240 supported L. Mayhew, and grant number 80NSSC21K0330 supported A.U. CNRS and CNES supported the work in France. DLR supported S.Sc. and D.S.V. The Swedish National Space Agency (contracts 137/19 and 2021-00092) supported S.Si. The Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canadian Space Agency (CSA) supported E.C., S.C., and N.T. The Ministry of Economy and Competitiveness (MINECO, SPAIN) grant PID2019-107442RB-C31 supported F.R., G.L.R., J.A.M., and M.

Published
2022
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3. On an Extensive Late Hydrologic Event in Gale Crater as Indicated by Water‐Rich Fracture Halos.

Author

Gabriel, Travis S. J., Hardgrove, Craig, Achilles, Cherie N., Rampe, Elizabeth B., Rapin, William N., Nowicki, Suzanne, Czarnecki, Sean, Thompson, Lucy, Nikiforov, Sergei, Litvak, Maxim, Mitrofanov, Igor, Lisov, Denis, Frydenvang, Jens, Yen, Albert, Wiens, Roger C., Treiman, Allan, and McAdam, Amy

Subjects
GALE Crater (Mars), MARS rovers, NEUTRON measurement, SEDIMENTARY rocks, SILICA, LUNAR craters
Abstract

We analyze spatially pervasive, light‐toned "halos" associated with fractures in a sedimentary unit (Stimson) of Gale crater, Mars, and report a similar network of halos discovered in a separate geologic group (Bradbury). Through a dedicated active neutron measurement campaign, we provide independent confirmation of the water‐rich nature of these features. Together with mineralogical and geochemical data, these features are consistent with abundant hydrated amorphous silica (opal‐A). We suggest that the mineral and amorphous assemblages are indicative of formation under low‐temperature and predominantly low‐pH conditions (passive silica enrichment) with minor contribution of silica (active silica enrichment) from adjacent units. We show that there is significant amorphous silica in the array of sedimentary rocks in Gale crater, allowing them to play a role in an active silica enrichment phase of halo formation. We suggest that the involved alteration event was short lived and our finding of vast halo networks in a distant, older unit implies a more vast network of hydrologic subsurface conduits than previously known. This relatively recent subsurface hydrologic system was present long after the transition from a warm and wet to a cold and dry Martian environment, extending the habitability conditions on Mars to an epoch that is generally considered not favorable for life on the surface. Finally, our bulk H quantification of these features, which ranges from ∼3–6 wt% H2O‐equivalent‐H, suggests that the amorphous material in halos hosts ample supplies of readily released water, making them a considerable resource at the otherwise dry Martian equator. Plain Language Summary: Light‐toned opaline silica features found throughout rocks along Curiosity rover's traverse are the exposed roots of a vast fluid event in recent Martian geologic history. Using data collected from several instruments on Curiosity rover, we find evidence that the event was short lived and was followed by consistently cold and dry Mars climate conditions. This water‐rich subsurface network was shielded from modern harsh surface conditions, allowing for a potentially habitable environment on Mars in a more recent era. These light‐toned features are also ideal for follow‐up investigation or sample return as similar opal‐rich deposits on Earth are known to preserve traces of microbial life. Additionally, the features themselves contain a considerable amount of readily released water, making them an ideal resource at the otherwise dry Martian equator. Key Points: We demonstrate that water‐rich, opal‐A‐bearing light‐toned halos are more prevalent in Gale crater, Mars than previously understoodHalos are associated with the conduits of a large‐scale hydrologic system in Gale craterHalos provided a subsurface habitable environment during a modern epoch of otherwise relatively uninhabitable surface conditions [ABSTRACT FROM AUTHOR]

Published
2022
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4. Clustering Supported Classification of ChemCam Data From Gale Crater, Mars.

Author

Rammelkamp, Kristin, Gasnault, Olivier, Forni, Olivier, Bedford, Candice C., Dehouck, Erwin, Cousin, Agnès, Lasue, Jeremie, David, Gaël, Gabriel, Travis S. J., Maurice, Sylvestre, and Wiens, Roger C.

Subjects
GALE Crater (Mars), CHEMOSTRATIGRAPHY, MARS (Planet), LASER-induced breakdown spectroscopy, K-means clustering, MATRIX decomposition
Abstract

The Chemistry and Camera (ChemCam) instrument on board the Mars Science Laboratory (MSL) rover Curiosity has collected a very large and unique data set of in‐situ spectra and images of Mars since landing in August 2012. More than 800,000 single shot laser‐induced breakdown spectroscopy (LIBS) spectra measured on more than 2,500 individual targets were returned so far by ChemCam. Such a data set is ideally suited for the application of statistical methods for the recognition of patterns that are difficult to observe by humans. In this work, we develop an approach relying on the feature extraction method Non‐Negative Matrix Factorization (NMF) and the repetition of k‐means clustering to classify ChemCam spectra. A strong consistency of the clustering results among the repetitions were found, which allowed us to identify six clusters representing the dominant compositions measured by ChemCam in Gale crater so far. By tracking clusters across the rover traverse from landing to sol 2756, we are able to provide a chemostratigraphic overview of the Gale crater from the ChemCam perspective. Transitions between major geologic groups (such as the Bradbury and the Mt. Sharp groups) are identifiable demonstrating that they are compositionally distinct, consistent with previous work. Compositional differences between their members also appear in the results. Furthermore, a first approach in which a random forest classifier was trained and validated with the obtained cluster assignments, reveals promising results for predicting cluster memberships of new ChemCam LIBS data acquired after sol 2756. Key Points: With a combination of feature extraction and repeated k‐means clustering applied to ChemCam LIBS data, we identify six clusters representing dominant compositions in Gale craterThe cluster detections are in agreement with the chemostratigraphy explored by CuriosityWe successfully trained a random forest classifier with the obtained cluster labels and used it to classify recent ChemCam targets [ABSTRACT FROM AUTHOR]

Published
2021
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5. Post-landing major element quantification using SuperCam laser induced breakdown spectroscopy.

Author

Anderson, Ryan B., Forni, Olivier, Cousin, Agnes, Wiens, Roger C., Clegg, Samuel M., Frydenvang, Jens, Gabriel, Travis S.J., Ollila, Ann, Schröder, Susanne, Beyssac, Olivier, Gibbons, Erin, Vogt, David S., Clavé, Elise, Manrique, Jose-Antonio, Legett IV, Carey, Pilleri, Paolo, Newell, Raymond T., Sarrao, Joseph, Maurice, Sylvestre, and Arana, Gorka

Subjects
*LASER-induced breakdown spectroscopy, *ALUMINUM oxide, *STANDARD deviations, *LASER ablation inductively coupled plasma mass spectrometry, *MANGANESE
Abstract

The SuperCam instrument on the Perseverance Mars 2020 rover uses a pulsed 1064 nm laser to ablate targets at a distance and conduct laser induced breakdown spectroscopy (LIBS) by analyzing the light from the resulting plasma. SuperCam LIBS spectra are preprocessed to remove ambient light, noise, and the continuum signal present in LIBS observations. Prior to quantification, spectra are masked to remove noisier spectrometer regions and spectra are normalized to minimize signal fluctuations and effects of target distance. In some cases, the spectra are also standardized or binned prior to quantification. To determine quantitative elemental compositions of diverse geologic materials at Jezero crater, Mars, we use a suite of 1198 laboratory spectra of 334 well-characterized reference samples. The samples were selected to span a wide range of compositions and include typical silicate rocks, pure minerals (e.g., silicates, sulfates, carbonates, oxides), more unusual compositions (e.g., Mn ore and sodalite), and replicates of the sintered SuperCam calibration targets (SCCTs) onboard the rover. For each major element (SiO 2 , TiO 2 , Al 2 O 3 , FeO T , MgO, CaO, Na 2 O, K 2 O), the database was subdivided into five "folds" with similar distributions of the element of interest. One fold was held out as an independent test set, and the remaining four folds were used to optimize multivariate regression models relating the spectrum to the composition. We considered a variety of models, and selected several for further investigation for each element, based primarily on the root mean squared error of prediction (RMSEP) on the test set, when analyzed at 3 m. In cases with several models of comparable performance at 3 m, we incorporated the SCCT performance at different distances to choose the preferred model. Shortly after landing on Mars and collecting initial spectra of geologic targets, we selected one model per element. Subsequently, with additional data from geologic targets, some models were revised to ensure results that are more consistent with geochemical constraints. The calibration discussed here is a snapshot of an ongoing effort to deliver the most accurate chemical compositions with SuperCam LIBS. [Display omitted] • We quantify the following oxides: SiO2, TiO2, Al2O3, FeOT, MgO, CaO, Na2O, K2O. • Multivariate regression models were trained on a diverse suite of spectra. • Of the algorithms considered, ensemble methods performed well but had limitations. • We evaluated models based on laboratory and Mars results. • Work is ongoing to improve major element results and quantify additional elements. [ABSTRACT FROM AUTHOR]

Published
2022
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