ORCID Profile
0000-0003-0602-484X
Current Organisation
NASA Jet Propulsion Laboratory
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Publisher: American Geophysical Union (AGU)
Date: 10-2023
DOI: 10.1029/2022JE007444
Abstract: In situ geologic context mapping (GXM) based on rover and helicopter observations provides documentation of a nearly continuous record of geology and exposed surface structure over a 120 m‐wide corridor along the traverse of the Mars 2020 /Perseverance rover. The results record the geologic context of Mars 2020 c aign sites and s le sites including the local extent of bedrock outcrops, stratigraphy, attitude, and structure from imaging and rover‐based remote sensing, and outcrop lithology based on in situ proximity science. Mapping identifies a sequence of igneous lithologies including: (1) early mafic, possibly intrusive, rocks (2) pervasively fractured and deeply altered massive bedrock of undetermined protolith (3) buried and exhumed lava flows with pahoehoe and aa textures (4) several varieties of regolith and (5) small impact craters.
Publisher: American Geophysical Union (AGU)
Date: 10-2023
DOI: 10.1029/2022JE007433
Abstract: Martian soils are critically important for understanding the history of Mars, past potentially habitable environments, returned s les, and future human exploration. This paper 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, 2 out of 7 helicopter flights that crossed the wheel tracks, and 4 of 8 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.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-11-2021
Abstract: The Perseverance rover landed in Jezero crater, Mars, in February 2021. Earlier orbital images showed that the crater contains an ancient river delta that was deposited by water flowing into a lake billions of years ago. Mangold et al . analyzed rover images taken shortly after landing that show distant cliff faces at the edge of the delta. The exposed stratigraphy and sizes of boulders allowed them to determine the past lake level and water discharge rates. An initially steady flow transitioned into intermittent floods as the planet dried out. This history of the delta’s geology provides context for the rest of the mission and improves our understanding of Mars’ ancient climate. —KTS
Publisher: Springer Science and Business Media LLC
Date: 03-11-2020
Location: United States of America
No related grants have been discovered for Nathan Williams.