An Examination of Soil Crusts on the Floor of Jezero Crater, Mars
Elisabeth M. Hausrath, C. T. Adcock, Andreas Bechtold, P. Beck, Kathleen C. Benison, A. J. Brown, Emily Cardarelli, Nancy Carman, Baptiste Chide, John R. Christian, B. C. Clark, E. A. Cloutis, A. Cousin, O. Forni, T. S. J. Gabriel, O. Gasnault, M. P. Golombek, Felipe Gómez, M. H. Hecht, T. L. J. Henley, Jennifer Huidobro, J. R. Johnson, Michael W. Jones, P. B. Kelemen, Abigail L. Knight, J. Lasue, Stéphane Le Mouëlic, Juan Manuel Madariaga, J. N. Maki, Lucia Mandon, Germán Martínez, Jesús Martínez‐Frías, T. H. McConnochie, Pierre‐Yves Meslin, María‐Paz Zorzano, H. E. Newsom, Gerhard Paar, Nicolas Randazzo, Clément Royer, Sandra Siljeström, M. E. Schmidt, Susanne Schröder, Mark A. Sephton, R. Sullivan, Nathalie Turenne, Arya Udry, S. J. VanBommel, Alicia Vaughan, R. C. Wiens, N. R. Williams, the SuperCam team and the Regolith working group
Abstract
Abstract Martian soils are critically important for understanding the history of Mars, past potentially habitable environments, returned samples, and future human exploration. This study examines soil crusts on the floor of Jezero crater encountered during initial phases of the Mars 2020 mission. Soil surface crusts have been observed on Mars at other locations, starting with the two Viking Lander missions. Rover observations show that soil crusts are also common across the floor of Jezero crater, revealed in 45 of 101 locations where rover wheels disturbed the soil surface, two out of seven helicopter flights that crossed the wheel tracks, and four of eight abrasion/drilling sites. Most soils measured by the SuperCam laser‐induced breakdown spectroscopy (LIBS) instrument show high hydrogen content at the surface, and fine‐grained soils also show a visible/near infrared (VISIR) 1.9 μm H 2 O absorption feature. The Planetary Instrument for X‐ray Lithochemistry (PIXL) and SuperCam observations suggest the presence of salts at the surface of rocks and soils. The correlation of S and Cl contents with H contents in SuperCam LIBS measurements suggests that the salts present are likely hydrated. On the “Naltsos” target, magnesium and sulfur are correlated in PIXL measurements, and Mg is tightly correlated with H at the SuperCam points, suggesting hydrated Mg‐sulfates. Mars Environmental Dynamics Analyzer (MEDA) observations indicate possible frost events and potential changes in the hydration of Mg‐sulfate salts. Jezero crater soil crusts may therefore form by salts that are hydrated by changes in relative humidity and frost events, cementing the soil surface together.