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In situ geologic context mapping 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/Perseverancerover. The results record the geologic context of Mars 2020 campaign sites and sample 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 (a) early mafic, possibly intrusive, rocks; (b) pervasively fractured and deeply altered massive bedrock of undetermined protolith; (c) buried and exhumed lava flows with pahoehoe and aa textures; (d) several varieties of regolith; and (e) small impact craters. Reconnaissance‐type geologic mapping along the traverse of Perseverance on the Jezero Crater floor is adapted from field geologic methods used on Earth and modified to account for the geometry of rover‐based imaging. The final field geologic map records bedrock and surficial geology, contacts, and structures over a 120‐m wide strip along the traverse. Most of the lithologies are igneous, including possible intrusive mafic rocks, deeply weathered massive rocks of unknown original lithology, and lava flows. Stratigraphy determined from mapping together with the observed inclination of layers identifies either uplift or draping of the section centered in the elevated older terrain. The final map information provides ground‐truth geologic context for the first eight samples collected for return to Earth. In situ mapping from the rover observations on Mars uses field geologic mapping methodsDocuments the geologic context of samples and the crater floor traverse of PerseveranceDevelops methods applicable to future robotic and human traverses on planetary surfaces In situ mapping from the rover observations on Mars uses field geologic mapping methods Documents the geologic context of samples and the crater floor traverse of Perseverance Develops methods applicable to future robotic and human traverses on planetary surfaces

The sample analysis at Mars instrument evolved gas analyzer (SAM‐EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2(160 ± 248–2373 ± 820 μgC(CO2)/g) and CO (11 ± 3–320 ± 130 μgC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2at temperatures consistent with carbonate (0.32 ± 0.05–0.70 ± 0.1 wt % CO3). Evolved NO amounts to 0.002 ± 0.007–0.06 ± 0.03 wt % NO3. Evolution of O2suggests that oxychlorine phases (chlorate/perchlorate) (0.05 ± 0.025–1.05 ± 0.44 wt % ClO4) are present, while SO2evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 ± 0.3–2.5 ± 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha‐Particle X‐ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population. The SAM instrument has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from Gale Crater sediments and sedimentary rockSAM detections are consistent with the presence of nitrate, organic C, carbonate, phyllosilicates, perchlorate, chlorate, and sulfateGale Crater materials have experienced a complex authigenetic/diagenetic history with fluids of varying pH, redox, and salt composition

During the first year of NASA's Mars 2020 mission, Perseverance rover has investigated the dark crater floor unit of Jezero crater and four samples of this unit have been collected. The focus of this paper is to assess the potential of these samples to calibrate the crater‐based Martian chronology. We first review the previous estimation of crater‐based model age of this unit. Then, we investigate the impact crater density distribution across the floor unit. It reveals that the crater density is heterogeneous from areas which have been exposed to the bombardment during the last 3 Ga to areas very recently exposed to bombardment. It suggests a complex history of exposure to impact cratering. We also display evidence of several remnants of deposits on the top of the dark floor unit across Jezero below which the dark floor unit may have been buried. We propose the following scenario of burying/exhumation: the dark floor unit would have been initially buried below a unit that was a few tens of meters thick. This unit then gradually eroded away due to Aeolian processes from the northeast to the west, resulting in uneven exposure to impact bombardment over 3 Ga. A cratering model reproducing this scenario confirms the feasibility of this hypothesis. Due to the complexity of its exposure history, the Jezero dark crater floor unit will require additional detailed analysis to understand how the Mars 2020 mission samples of the crater floor can be used to inform the Martian cratering chronology. Perseverance rover landed within Jezero crater (Mars) in 2021 and is collecting rocks that will be returned to Earth. In terrestrial state‐of‐the art labs, these rocks will be dated. It will allow to test the method planetary scientists are using to assess the age of Martian surfaces: their impact crater statistics. As impact craters are forming regularly, their statistics are used as a timeline in planetary sciences. The present paper studies the statistic of impacts craters within Jezero crater to reveal that the floor of Jezero has been protected from bombardment during years. These results imply that the collected rocks of the Jezero crater floor will not be ideal to test the method of using impact crater as chronometer of Martian surfaces. The dark floor unit of the Jezero crater displays an unusual inhomogeneous crater density, suggesting a complex exhumation historyThe crater density of the dark crater floor unit corresponds to the exposure time post exhumationThe crater density of this unit will not allow the calibration of the Martian crater chronology from return samples The dark floor unit of the Jezero crater displays an unusual inhomogeneous crater density, suggesting a complex exhumation history The crater density of the dark crater floor unit corresponds to the exposure time post exhumation The crater density of this unit will not allow the calibration of the Martian crater chronology from return samples

Ventifacts, rocks abraded by wind‐borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter‐scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high‐speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today. Ventifacts in Gale CraterMay be formed by paleowindCan see abrasion textures at range of scales

The Mars Science Laboratory mission reached Bradbury Landing in August 2012. In its first 500 sols, the rover Curiositywas commissioned and began its investigation of the habitability of past and present environments within Gale Crater. Curiositytraversed eastward toward Glenelg, investigating a boulder with a highly alkaline basaltic composition, encountering numerous exposures of outcropping pebble conglomerate, and sampling aeolian sediment at Rocknest and lacustrine mudstones at Yellowknife Bay. On sol 324, the mission turned its focus southwest, beginning a year‐long journey to the lower reaches of Mt. Sharp, with brief stops at the Darwin and Cooperstown waypoints. The unprecedented complexity of the rover and payload systems posed challenges to science operations, as did a number of anomalies. Operational processes were revised to include additional opportunities for advance planning by the science and engineering teams. Curiosity has investigated the habitability of Gale Crater, MarsCuriosity has explored environments with evidence of ancient fluvial activityThe unprecedented complexity of the rover challenged science operations

On February 18, 2021 NASA's Perseverance rover landed in Jezero crater, located at the northwestern edge of the Isidis basin on Mars. The uppermost surface of the present‐day crater floor is dominated by a distinct geologic assemblage previously referred to as the dark‐toned floor. It consists of a smooth, dark‐toned unit overlying and variably covering light‐toned, roughly eroded deposits showing evidence of discrete layers. In this study, we investigated the stratigraphic relations between materials that comprise this assemblage, the main western delta deposit, as well as isolated mesas located east of the main delta body that potentially represent delta remnants. A more detailed classification and differentiation of crater floor units in Jezero and determination of their relative ages is vital for the understanding of the geologic evolution of the crater system, and determination of the potential timeline and environments of habitability. We have investigated unit contacts using topographic profiles and DEMs as well as the distribution of small craters and fractures on the youngest portions of the crater floor. Our results indicate that at least some of the deltaic deposition in Jezero postdates emplacement of the uppermost surface of the crater floor assemblage. The inferred age of the floor assemblage can therefore help to constrain the timing of the Jezero fluviolacustrine system, wherein at least some lake activity postdates the age of the uppermost crater floor. We present hypotheses that can be tested by Perseverance and can be used to advance our knowledge of the geologic evolution of the area. On February 18, 2021 NASA's Perseverance rover landed in Jezero crater on Mars. In the past, the crater was filled with water, forming a lake, and in the western part of the crater an ancient delta is preserved. Part of the present‐day crater floor has been interpreted to represent a lava flow that was deposited after the lake dried out, meaning that the floor unit would be younger than the western delta. In order to understand how the Jezero crater lake has developed over time, including the potential timeline and environments of habitability, it is necessary to work out the relations between the geologic units in Jezero crater. In this work, we have analyzed orbital images of Jezero crater and reveal how the crater floor and delta deposits relate to each other in time. Our results show that at least some of the deltaic deposits in Jezero overlie the youngest crater floor unit(s). It is therefore possible to learn broadly when fluvial activity in the crater has been effective from the age of the crater floor. Our work presents hypotheses that can be tested by Perseverance to advance our knowledge of how the area has evolved geologically over time. We have studied stratigraphic relations between geologic units in Jezero crater for determination of relative age relations in the craterTopographic profiles and digital elevation models indicate that the western delta is on top of the youngest crater floor unit(s)We thus place constraints on the timeline of fluvial‐lacustrine activity in Jezero crater We have studied stratigraphic relations between geologic units in Jezero crater for determination of relative age relations in the crater Topographic profiles and digital elevation models indicate that the western delta is on top of the youngest crater floor unit(s) We thus place constraints on the timeline of fluvial‐lacustrine activity in Jezero crater