Eva L. Scheller

All Publications

• Photogeologic Map of the Perseverance Rover Field Site in Jezero Crater Constructed by the Mars 2020 Science Team (vol 216, 127, 2020) SPACE SCIENCE REVIEWS Stack, K. M., Williams, N. R., Calef, F., Sun, V. Z., Williford, K. H., Farley, K. A., Eide, S., Flannery, D., Hughes, C., Jacob, S. R., Kah, L. C., Meyen, F., Molina, A., Nataf, C., Rice, M., Russell, P., Scheller, E., Seeger, C. H., Abbey, W. J., Adler, J. B., Amundsen, H., Anderson, R. B., Angel, S. M., Arana, G., Atkins, J., Barrington, M., Berger, T., Borden, R., Boring, B., Brown, A., Carrier, B. L., Conrad, P., Dypvik, H., Fagents, S. A., Gallegos, Z. E., Garczynski, B., Golder, K., Gomez, F., Goreva, Y., Gupta, S., Hamran, S., Hicks, T., Hinterman, E. D., Horgan, B. N., Hurowitz, J., Johnson, J. R., Lasue, J., Kronyak, R. E., Liu, Y., Madariaga, J., Mangold, N., Mcclean, J., Miklusicak, N., Nunes, D., Rojas, C., Runyon, K., Schmitz, N., Scudder, N., Shaver, E., Soohoo, J., Spaulding, R., Stanish, E., Tamppari, L. K., Tice, M. M., Turenne, N., Willis, P. A., Aileen Yingst, R. 2025; 221 (6)

  View details for DOI 10.1007/s11214-025-01204-3

  View details for Web of Science ID 001553000700001

• Spectral Background Calibration of Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Spectrometer Onboard the Perseverance Rover Enables Identification of a Ubiquitous Martian Spectral Component. Applied spectroscopy Jakubek, R. S., Corpolongo, A., Bhartia, R., Morris, R. V., Uckert, K., Asher, S. A., Burton, A. S., Fries, M. D., Hand, K., Hug, W. F., Lee, C., McCubbin, F. M., Scheller, E. L., Sharma, S., Siljeström, S., Steele, A. 2025; 79 (6): 904-918

  Abstract

  The Perseverance rover landed at Jezero Crater, Mars, on 18 February 2021, with a payload of scientific instruments to examine Mars' past habitability, look for signs of past life, and process samples for future return to Earth. The instrument payload includes the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) deep ultraviolet Raman and fluorescence imaging spectrometer designed to detect, characterize, and map the presence of organics and minerals on the Martian surface. Operation and engineering constraints sometimes result in the acquisition of spectra with features near the detection limit. It is therefore important to separate instrumental (background) spectral components and spectral components inherent to Martian surface materials. For SHERLOC, the instrumental background is assessed by collecting spectra in the stowed-arm configuration where the instrument is pointed at the Martian nighttime sky with no surface sample present in its optical path. These measurements reveal weak Raman and fluorescence background spectral signatures as well as charged-coupled device pixels prone to erroneous intensity spikes separate from cosmic rays. We quantitatively describe these features and provide a subtraction procedure to remove the spectral background from surface spectra. By identifying and accounting for the SHERLOC Raman background features within the median Raman spectra of Martian target scans, we find that the undefined silicate spectral feature interpreted to be either amorphous silicate or plagioclase feldspar is ubiquitously found in every Mars target Raman scan collected through Sol 751.

  View details for DOI 10.1177/00037028241280081

  View details for PubMedID 39359239

• Episodic warm climates on early Mars primed by crustal hydration NATURE GEOSCIENCE Adams, D., Scheucher, M., Hu, R., Ehlmann, B. L., Thomas, T. B., Wordsworth, R., Scheller, E., Lillis, R., Smith, K., Rauer, H., Yung, Y. L. 2025; 18 (2)

  View details for DOI 10.1038/s41561-024-01626-8

  View details for Web of Science ID 001406463200001

• Inorganic interpretation of luminescent materials encountered by the Perseverance rover on Mars. Science advances Scheller, E. L., Bosak, T., McCubbin, F. M., Williford, K., Siljestrom, S., Jakubek, R. S., Eckley, S. A., Morris, R. V., Bykov, S. V., Kizovski, T., Asher, S., Berger, E., Bower, D. M., Cardarelli, E. L., Ehlmann, B. L., Fornaro, T., Fox, A., Haney, N., Hand, K., Roppel, R., Sharma, S., Steele, A., Uckert, K., Yanchilina, A. G., Beyssac, O., Farley, K. A., Henneke, J., Heirwegh, C., Pedersen, D. A., Liu, Y., Schmidt, M. E., Sephton, M., Shuster, D., Weiss, B. P. 2024; 10 (39): eadm8241

  Abstract

  A major objective of the Mars 2020 mission is to sample rocks in Jezero crater that may preserve organic matter for later return to Earth. Using an ultraviolet Raman and luminescence spectrometer, the Perseverance rover detected luminescence signals with maximal intensities at 330 to 350 nanometers and 270 to 290 nanometers that were initially reported as consistent with organics. Here, we test the alternative hypothesis that the 330- to 350-nanometer and 270- to 290-nanometer luminescence signals trace Ce3+ in phosphate and silicate defects, respectively. By comparing the distributions of luminescence signals with the rover detections of x-ray fluorescence from P2O5 and Si-bearing materials, we show that, while an organic origin is not excluded, the observed luminescence can be explained by purely inorganic materials. These findings highlight the importance of eventual laboratory analyses to detect and characterize organic compounds in the returned samples.

  View details for DOI 10.1126/sciadv.adm8241

  View details for PubMedID 39321302

• Likely Ferromagnetic Minerals Identified by the Perseverance Rover and Implications for Future Paleomagnetic Analyses of Returned Martian Samples JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Mansbach, E. N., Kizovski, T. V., Scheller, E. L., Bosak, T., Mandon, L., Horgan, B., Wiens, R. C., Herd, C. D. K., Sharma, S., Johnson, J. R., Gabriel, T. S. J., Forni, O., Liu, Y., Schmidt, M. E., Weiss, B. P. 2024; 129 (9)

  View details for DOI 10.1029/2024JE008505

  View details for Web of Science ID 001318385000001

• Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars AGU ADVANCES Bosak, T., Shuster, D. L., Scheller, E. L., Siljestroem, S., Zawaski, M. J., Mandon, L., Simon, J. I., Weiss, B. P., Stack, K. M., Mansbach, E. N., Treiman, A. H., Benison, K. C., Brown, A. J., Czaja, A. D., Farley, K. A., Hausrath, E. M., Hickman-Lewis, K., Herd, C. K., Johnson, J. R., Mayhew, L. E., Minitti, M. E., Williford, K. H., Wogsland, B. V., Zorzano, M., Allwood, A. C., Amundsen, H. F., Bell, J. F., Benzerara, K., Bernard, S., Beyssac, O., Buckner, D. K., Cable, M., Calef, F., Caravaca, G., Catling, D. C., Clave, E., Cloutis, E., Cohen, B. A., Cousin, A., Dehouck, E., Fairen, A. G., Flannery, D. T., Fornaro, T., Forni, O., Fouchet, T., Gibbons, E., Gomez, F., Gupta, S., Hand, K. P., Hurowitz, J. A., Kalucha, H., Pedersen, D. K., Lopes-Reyes, G., Maki, J. N., Maurice, S., Nunez, J. I., Randazzo, N., Rice, J. W., Royer, C., Sephton, M. A., Sharma, S., Steele, A., Tate, C. D., Uckert, K., Udry, A., Wiens, R. C., Williams, A. 2024; 5 (4)

  View details for DOI 10.1029/2024AV001241

  View details for Web of Science ID 001290371800001

• Characterizing Hydrated Sulfates and Altered Phases in Jezero Crater Fan and Floor Geologic Units With SHERLOC on Mars 2020 JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Phua, Y., Ehlmann, B. L., Siljestroem, S., Czaja, A. D., Beck, P., Connell, S., Wiens, R. C., Jakubek, R. S., Williams, R. M. E., Zorzano, M., Minitti, M. E., Pascuzzo, A. C., Hand, K. P., Bhartia, R., Kah, L. C., Mandon, L., Razzell Hollis, J., Scheller, E. L., Sharma, S., Steele, A., Uckert, K., Williford, K. H., Yanchilina, A. G. 2024; 129 (7)

  View details for DOI 10.1029/2023JE008251

  View details for Web of Science ID 001272951200001

• Evidence of Sulfate-Rich Fluid Alteration in Jezero Crater Floor, Mars JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Siljestrom, S., Czaja, A. D., Corpolongo, A., Berger, E. L., Li, A. Y., Cardarelli, E., Abbey, W., Asher, S. A., Beegle, L. W., Benison, K. C., Bhartia, R., Bleefeld, B. L., Burton, A. S., Bykov, S. V., Clark, B., DeFlores, L., Ehlmann, B. L., Fornaro, T., Fox, A., Gomez, F., Hand, K., Haney, N. C., Hickman-Lewis, K., Hug, W. F., Imbeah, S., Jakubek, R. S., Kah, L. C., Kivrak, L., Lee, C., Liu, Y., Martinez-Frias, J., McCubbin, F. M., Minitti, M., Moore, K., Morris, R. V., Nunez, J. I., Osterhout, J. T., Phua, Y., Randazzo, N., Hollis, J., Rodriguez, C., Roppel, R., Scheller, E. L., Sephton, M., Sharma, S. K., Sharma, S., Steadman, K., Steele, A., Tice, M., Uckert, K., VanBommel, S., Williams, A. J., Williford, K. H., Winchell, K., Wu, M., Yanchilina, A., Zorzano, M. 2024; 129 (1)

  View details for DOI 10.1029/2023JE007989

  View details for Web of Science ID 001150853100001

• Science and Science-Enabling Activities of the SHERLOC and WATSON Imaging Systems in Jezero Crater, Mars EARTH AND SPACE SCIENCE Wogsland, B. V., Minitti, M. E., Kah, L. C., Yingst, R. A., Abbey, W., Bhartia, R., Beegle, L., Bleefeld, B. L., Cardarelli, E. L., Conrad, P. G., Edgett, K., Hickman-Lewis, K., Hugget, J., Imbeah, S., Kennedy, M. R., Lee, C., Nixon, B. E., Nunez, J. I., Pascuzzo, A., Robinson, M., Sanchez-Vahamonde, C., Scheller, E., Sharma, S., Siljestrom, S., Steadman, K., Winchell, K., Ravine, M. A. 2023; 10 (11)

  View details for DOI 10.1029/2022EA002544

  View details for Web of Science ID 001096045500001

• Diverse organic-mineral associations in Jezero crater, Mars. Nature Sharma, S., Roppel, R. D., Murphy, A. E., Beegle, L. W., Bhartia, R., Steele, A., Hollis, J. R., Siljeström, S., McCubbin, F. M., Asher, S. A., Abbey, W. J., Allwood, A. C., Berger, E. L., Bleefeld, B. L., Burton, A. S., Bykov, S. V., Cardarelli, E. L., Conrad, P. G., Corpolongo, A., Czaja, A. D., DeFlores, L. P., Edgett, K., Farley, K. A., Fornaro, T., Fox, A. C., Fries, M. D., Harker, D., Hickman-Lewis, K., Huggett, J., Imbeah, S., Jakubek, R. S., Kah, L. C., Lee, C., Liu, Y., Magee, A., Minitti, M., Moore, K. R., Pascuzzo, A., Rodriguez Sanchez-Vahamonde, C., Scheller, E. L., Shkolyar, S., Stack, K. M., Steadman, K., Tuite, M., Uckert, K., Werynski, A., Wiens, R. C., Williams, A. J., Winchell, K., Kennedy, M. R., Yanchilina, A. 2023; 619 (7971): 724-732

  Abstract

  The presence and distribution of preserved organic matter on the surface of Mars can provide key information about the Martian carbon cycle and the potential of the planet to host life throughout its history. Several types of organic molecules have been previously detected in Martian meteorites1 and at Gale crater, Mars2-4. Evaluating the diversity and detectability of organic matter elsewhere on Mars is important for understanding the extent and diversity of Martian surface processes and the potential availability of carbon sources1,5,6. Here we report the detection of Raman and fluorescence spectra consistent with several species of aromatic organic molecules in the Máaz and Séítah formations within the Crater Floor sequences of Jezero crater, Mars. We report specific fluorescence-mineral associations consistent with many classes of organic molecules occurring in different spatial patterns within these compositionally distinct formations, potentially indicating different fates of carbon across environments. Our findings suggest there may be a diversity of aromatic molecules prevalent on the Martian surface, and these materials persist despite exposure to surface conditions. These potential organic molecules are largely found within minerals linked to aqueous processes, indicating that these processes may have had a key role in organic synthesis, transport or preservation.

  View details for DOI 10.1038/s41586-023-06143-z

  View details for PubMedID 37438522

  View details for PubMedCentralID PMC10371864

• The mechanisms and stable isotope effects of transforming hydrated carbonate into calcite pseudomorphs GEOCHIMICA ET COSMOCHIMICA ACTA Scheller, E. L., Ingalls, M., Eiler, J. M., Grotzinger, J. P., Ryb, U. 2023; 354: 146-164

  View details for DOI 10.1016/j.gca.2023.04.025

  View details for Web of Science ID 001027665500001

• SHERLOC Raman Mineral Class Detections of the Mars 2020 Crater Floor Campaign JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Corpolongo, A., Jakubek, R. S. S., Burton, A. S. S., Brown, A. J. J., Yanchilina, A., Czaja, A. D. D., Steele, A., Wogsland, B. V. V., Lee, C., Flannery, D., Baker, D., Cloutis, E. A. A., Cardarelli, E., Scheller, E. L. L., Berger, E. L. L., McCubbin, F. M. M., Hollis, J., Hickman-Lewis, K., Steadman, K., Uckert, K., DeFlores, L., Kah, L., Beegle, L. W. W., Fries, M., Minitti, M., Haney, N. C. C., Conrad, P., Morris, R. V. V., Bhartia, R., Roppel, R., Siljestroem, S., Asher, S. A. A., Bykov, S. V. V., Sharma, S., Shkolyar, S., Fornaro, T., Abbey, W. 2023; 128 (3)

  View details for DOI 10.1029/2022JE007455

  View details for Web of Science ID 000949083600001

• Aqueous alteration processes in Jezero crater, Mars-implications for organic geochemistry. Science (New York, N.Y.) Scheller, E. L., Razzell Hollis, J., Cardarelli, E. L., Steele, A., Beegle, L. W., Bhartia, R., Conrad, P., Uckert, K., Sharma, S., Ehlmann, B. L., Abbey, W. J., Asher, S. A., Benison, K. C., Berger, E. L., Beyssac, O., Bleefeld, B. L., Bosak, T., Brown, A. J., Burton, A. S., Bykov, S. V., Cloutis, E., Fairén, A. G., DeFlores, L., Farley, K. A., Fey, D. M., Fornaro, T., Fox, A. C., Fries, M., Hickman-Lewis, K., Hug, W. F., Huggett, J. E., Imbeah, S., Jakubek, R. S., Kah, L. C., Kelemen, P., Kennedy, M. R., Kizovski, T., Lee, C., Liu, Y., Mandon, L., McCubbin, F. M., Moore, K. R., Nixon, B. E., Núñez, J. I., Rodriguez Sanchez-Vahamonde, C., Roppel, R. D., Schulte, M., Sephton, M. A., Sharma, S. K., Siljeström, S., Shkolyar, S., Shuster, D. L., Simon, J. I., Smith, R. J., Stack, K. M., Steadman, K., Weiss, B. P., Werynski, A., Williams, A. J., Wiens, R. C., Williford, K. H., Winchell, K., Wogsland, B., Yanchilina, A., Yingling, R., Zorzano, M. P. 2022; 378 (6624): 1105-1110

  Abstract

  The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments.

  View details for DOI 10.1126/science.abo5204

  View details for PubMedID 36417498

• Geological, multispectral, and meteorological imaging results from the Mars 2020 Perseverance rover in Jezero crater. Science advances Bell, J. F., Maki, J. N., Alwmark, S., Ehlmann, B. L., Fagents, S. A., Grotzinger, J. P., Gupta, S., Hayes, A., Herkenhoff, K. E., Horgan, B. H., Johnson, J. R., Kinch, K. B., Lemmon, M. T., Madsen, M. B., Núñez, J. I., Paar, G., Rice, M., Rice, J. W., Schmitz, N., Sullivan, R., Vaughan, A., Wolff, M. J., Bechtold, A., Bosak, T., Duflot, L. E., Fairén, A. G., Garczynski, B., Jaumann, R., Merusi, M., Million, C., Ravanis, E., Shuster, D. L., Simon, J., St Clair, M., Tate, C., Walter, S., Weiss, B., Bailey, A. M., Bertrand, T., Beyssac, O., Brown, A. J., Caballo-Perucha, P., Caplinger, M. A., Caudill, C. M., Cary, F., Cisneros, E., Cloutis, E. A., Cluff, N., Corlies, P., Crawford, K., Curtis, S., Deen, R., Dixon, D., Donaldson, C., Barrington, M., Ficht, M., Fleron, S., Hansen, M., Harker, D., Howson, R., Huggett, J., Jacob, S., Jensen, E., Jensen, O. B., Jodhpurkar, M., Joseph, J., Juarez, C., Kah, L. C., Kanine, O., Kristensen, J., Kubacki, T., Lapo, K., Magee, A., Maimone, M., Mehall, G. L., Mehall, L., Mollerup, J., Viúdez-Moreiras, D., Paris, K., Powell, K. E., Preusker, F., Proton, J., Rojas, C., Sallurday, D., Saxton, K., Scheller, E., Seeger, C. H., Starr, M., Stein, N., Turenne, N., Van Beek, J., Winhold, A. G., Yingling, R. 2022; 8 (47): eabo4856

  Abstract

  Perseverance's Mastcam-Z instrument provides high-resolution stereo and multispectral images with a unique combination of spatial resolution, spatial coverage, and wavelength coverage along the rover's traverse in Jezero crater, Mars. Images reveal rocks consistent with an igneous (including volcanic and/or volcaniclastic) and/or impactite origin and limited aqueous alteration, including polygonally fractured rocks with weathered coatings; massive boulder-forming bedrock consisting of mafic silicates, ferric oxides, and/or iron-bearing alteration minerals; and coarsely layered outcrops dominated by olivine. Pyroxene dominates the iron-bearing mineralogy in the fine-grained regolith, while olivine dominates the coarse-grained regolith. Solar and atmospheric imaging observations show significant intra- and intersol variations in dust optical depth and water ice clouds, as well as unique examples of boundary layer vortex action from both natural (dust devil) and Ingenuity helicopter-induced dust lifting. High-resolution stereo imaging also provides geologic context for rover operations, other instrument observations, and sample selection, characterization, and confirmation.

  View details for DOI 10.1126/sciadv.abo4856

  View details for PubMedID 36417517

  View details for PubMedCentralID PMC9683734

• Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars. Science (New York, N.Y.) Farley, K. A., Stack, K. M., Shuster, D. L., Horgan, B. H., Hurowitz, J. A., Tarnas, J. D., Simon, J. I., Sun, V. Z., Scheller, E. L., Moore, K. R., McLennan, S. M., Vasconcelos, P. M., Wiens, R. C., Treiman, A. H., Mayhew, L. E., Beyssac, O., Kizovski, T. V., Tosca, N. J., Williford, K. H., Crumpler, L. S., Beegle, L. W., Bell, J. F., Ehlmann, B. L., Liu, Y., Maki, J. N., Schmidt, M. E., Allwood, A. C., Amundsen, H. E., Bhartia, R., Bosak, T., Brown, A. J., Clark, B. C., Cousin, A., Forni, O., Gabriel, T. S., Goreva, Y., Gupta, S., Hamran, S. E., Herd, C. D., Hickman-Lewis, K., Johnson, J. R., Kah, L. C., Kelemen, P. B., Kinch, K. B., Mandon, L., Mangold, N., Quantin-Nataf, C., Rice, M. S., Russell, P. S., Sharma, S., Siljeström, S., Steele, A., Sullivan, R., Wadhwa, M., Weiss, B. P., Williams, A. J., Wogsland, B. V., Willis, P. A., Acosta-Maeda, T. A., Beck, P., Benzerara, K., Bernard, S., Burton, A. S., Cardarelli, E. L., Chide, B., Clavé, E., Cloutis, E. A., Cohen, B. A., Czaja, A. D., Debaille, V., Dehouck, E., Fairén, A. G., Flannery, D. T., Fleron, S. Z., Fouchet, T., Frydenvang, J., Garczynski, B. J., Gibbons, E. F., Hausrath, E. M., Hayes, A. G., Henneke, J., Jørgensen, J. L., Kelly, E. M., Lasue, J., Le Mouélic, S., Madariaga, J. M., Maurice, S., Merusi, M., Meslin, P. Y., Milkovich, S. M., Million, C. C., Moeller, R. C., Núñez, J. I., Ollila, A. M., Paar, G., Paige, D. A., Pedersen, D. A., Pilleri, P., Pilorget, C., Pinet, P. C., Rice, J. W., Royer, C., Sautter, V., Schulte, M., Sephton, M. A., Sharma, S. K., Sholes, S. F., Spanovich, N., St Clair, M., Tate, C. D., Uckert, K., VanBommel, S. J., Yanchilina, A. G., Zorzano, M. P. 2022; 377 (6614): eabo2196

  Abstract

  The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater's sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

  View details for DOI 10.1126/science.abo2196

  View details for PubMedID 36007009

• Guttulatic calcite: A carbonate microtexture that reveals frigid formation conditions GEOLOGY Scheller, E. L., Grotzinger, J., Ingalls, M. 2022; 50 (1): 48-53

  View details for DOI 10.1130/G49312.1

  View details for Web of Science ID 000735380200009

• A deep-ultraviolet Raman and Fluorescence spectral library of 62 minerals for the SHERLOC instrument onboard Mars 2020 PLANETARY AND SPACE SCIENCE Hollis, J., Abbey, W., Beegle, L. W., Bhartia, R., Ehlmann, B. L., Miura, J., Monacelli, B., Moore, K., Nordman, A., Scheller, E., Uckert, K., Wu, Y. 2021; 209

  View details for DOI 10.1016/j.pss.2021.105356

  View details for Web of Science ID 000715133900004

• Formation of Magnesium Carbonates on Earth and Implications for Mars. Journal of geophysical research. Planets Scheller, E. L., Swindle, C., Grotzinger, J., Barnhart, H., Bhattacharjee, S., Ehlmann, B. L., Farley, K., Fischer, W. W., Greenberger, R., Ingalls, M., Martin, P. E., Osorio-Rodriguez, D., Smith, B. P. 2021; 126 (7): e2021JE006828

  Abstract

  Magnesium carbonates have been identified within the landing site of the Perseverance rover mission. This study reviews terrestrial analog environments and textural, mineral assemblage, isotopic, and elemental analyses that have been applied to establish formation conditions of magnesium carbonates. Magnesium carbonates form in five distinct settings: ultramafic rock-hosted veins, the matrix of carbonated peridotite, nodules in soil, alkaline lake, and playa deposits, and as diagenetic replacements within lime-and dolostones. Dominant textures include fine-grained or microcrystalline veins, nodules, and crusts. Microbial influences on formation are recorded in thrombolites, stromatolites, crinkly, and pustular laminites, spheroids, and filamentous microstructures. Mineral assemblages, fluid inclusions, and carbon, oxygen, magnesium, and clumped isotopes of carbon and oxygen have been used to determine the sources of carbon, magnesium, and fluid for magnesium carbonates as well as their temperatures of formation. Isotopic signatures in ultramafic rock-hosted magnesium carbonates reveal that they form by either low-temperature meteoric water infiltration and alteration, hydrothermal alteration, or metamorphic processes. Isotopic compositions of lacustrine magnesium carbonate record precipitation from lake water, evaporation processes, and ambient formation temperatures. Assessment of these features with similar analytical techniques applied to returned Martian samples can establish whether carbonates on ancient Mars were formed at high or low temperature conditions in the surface or subsurface through abiotic or biotic processes. The timing of carbonate formation processes could be constrained by 147Sm-143Nd isochron, U-Pb concordia, 207Pb-206Pb isochron radiometric dating as well as 3He, 21Ne, 22Ne, or 36Ar surface exposure dating of returned Martian magnesium carbonate samples.

  View details for DOI 10.1029/2021je006828

  View details for PubMedID 34422534

  View details for PubMedCentralID PMC8378241

• Long-term drying of Mars by sequestration of ocean-scale volumes of water in the crust. Science (New York, N.Y.) Scheller, E. L., Ehlmann, B. L., Hu, R., Adams, D. J., Yung, Y. L. 2021; 372 (6537): 56-62

  Abstract

  Geological evidence shows that ancient Mars had large volumes of liquid water. Models of past hydrogen escape to space, calibrated with observations of the current escape rate, cannot explain the present-day deuterium-to-hydrogen isotope ratio (D/H). We simulated volcanic degassing, atmospheric escape, and crustal hydration on Mars, incorporating observational constraints from spacecraft, rovers, and meteorites. We found that ancient water volumes equivalent to a 100 to 1500 meter global layer are simultaneously compatible with the geological evidence, loss rate estimates, and D/H measurements. In our model, the volume of water participating in the hydrological cycle decreased by 40 to 95% over the Noachian period (~3.7 billion to 4.1 billion years ago), reaching present-day values by ~3.0 billion years ago. Between 30 and 99% of martian water was sequestered through crustal hydration, demonstrating that irreversible chemical weathering can increase the aridity of terrestrial planets.

  View details for DOI 10.1126/science.abc7717

  View details for PubMedID 33727251

  View details for PubMedCentralID PMC8370096

• Generalized Unsupervised Clustering of Hyperspectral Images of Geological Targets in the Near Infrared Gao, A. F., Rasmussen, B., Kulits, P., Scheller, E. L., Greenberger, R., Ehlmann, B. L., IEEE Comp Soc IEEE COMPUTER SOC. 2021: 4289-4298

  View details for DOI 10.1109/CVPRW53098.2021.00485

  View details for Web of Science ID 000705890204051

• Photogeologic Map of the Perseverance Rover Field Site in Jezero Crater Constructed by the Mars 2020 Science Team. Space science reviews Stack, K. M., Williams, N. R., Calef, F., Sun, V. Z., Williford, K. H., Farley, K. A., Eide, S., Flannery, D., Hughes, C., Jacob, S. R., Kah, L. C., Meyen, F., Molina, A., Nataf, C. Q., Rice, M., Russell, P., Scheller, E., Seeger, C. H., Abbey, W. J., Adler, J. B., Amundsen, H., Anderson, R. B., Angel, S. M., Arana, G., Atkins, J., Barrington, M., Berger, T., Borden, R., Boring, B., Brown, A., Carrier, B. L., Conrad, P., Dypvik, H., Fagents, S. A., Gallegos, Z. E., Garczynski, B., Golder, K., Gomez, F., Goreva, Y., Gupta, S., Hamran, S. E., Hicks, T., Hinterman, E. D., Horgan, B. N., Hurowitz, J., Johnson, J. R., Lasue, J., Kronyak, R. E., Liu, Y., Madariaga, J. M., Mangold, N., McClean, J., Miklusicak, N., Nunes, D., Rojas, C., Runyon, K., Schmitz, N., Scudder, N., Shaver, E., SooHoo, J., Spaulding, R., Stanish, E., Tamppari, L. K., Tice, M. M., Turenne, N., Willis, P. A., Yingst, R. A. 2020; 216 (8)

  Abstract

  The Mars 2020 Perseverance rover landing site is located within Jezero crater, a ∼ 50 km diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study's map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance's exploration of Jezero crater.

  View details for DOI 10.1007/s11214-020-00739-x

  View details for PubMedID 33568875

  View details for PubMedCentralID PMC7116714

• Composition, Stratigraphy, and Geological History of the Noachian Basement Surrounding the Isidis Impact Basin. Journal of geophysical research. Planets Scheller, E. L., Ehlmann, B. L. 2020; 125 (7): e2019JE006190

  Abstract

  The western part of the Isidis basin structure hosts a well-characterized Early Noachian to Amazonian stratigraphy. The Noachian Basement comprises its oldest exposed rocks (Early to Mid-Noachian) and was previously considered a single low-Ca pyroxenes (LCP)- and Fe/Mg-smectite-bearing unit. Here, we divide the Noachian Basement Group into five distinct geological units (Stratified Basement Unit, Blue Fractured Unit, Mixed Lithology Plains Unit, LCP-bearing Plateaus Unit, and Fe/Mg-smectite-bearing Mounds Unit), two geomorphological features (megabreccia and ridges), and a mineral deposit (kaolinite-bearing bright materials), based on geomorphology, spectral characteristics, and stratigraphic relationships. Megabreccia contain four different pre-Isidis lithologies, possibly including deeper crust or mantle materials, formed through mass wasting associated with transient crater collapse during Isidis basin formation. The Fe/Mg-smectite-bearing Stratified Basement Unit and LCP-bearing Blue Fractured Unit likewise represent pre-Isidis units within the Noachian Basement Group. Multiple Fe/Mg-smectite-bearing geological units with different stratigraphic positions and younger kaolinite-bearing bright materials indicate several aqueous alteration episodes of different ages and styles. Units with slight changes in pyroxene spectral properties suggest a transition from low-Ca pyroxene-containing materials to those with higher proportions of pyroxenes higher in Ca and/or glass that could be related to different impact and/or igneous processes, or provenance. This long history of Noachian and potentially Pre-Noachian geological processes, including impact basin formation, aqueous alteration, and multiple igneous and sedimentary petrogeneses, records changing ancient Mars environmental conditions. All units defined by this study are available 20 km outside of Jezero crater for in situ analysis and sampling during a potential extended mission scenario for the Mars 2020 rover.

  View details for DOI 10.1029/2019je006190

  View details for PubMedID 34422533

  View details for PubMedCentralID PMC8378244

• Ocean redox conditions between the snowballs - Geochemical constraints from Arena Formation, East Greenland PRECAMBRIAN RESEARCH Scheller, E. L., Dickson, A. J., Canfield, D. E., Korte, C., Kristiansen, K. K., Dahl, T. W. 2018; 319: 173-186

  View details for DOI 10.1016/j.precamres.2017.12.009

  View details for Web of Science ID 000454376400011