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On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2–7 m, while providing data at sub-mm to mm scales. We report on SuperCam’s science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.

The Noachian terrain west of the Isidis basin hosts a diverse collection of alteration minerals in rocks comprising varied geomorphic units within a 100,000 km2 region in and near the Nili Fossae. Prior investigations in this region by the Observatoire pour l'Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) instrument on Mars Express revealed large exposures of both mafic minerals and iron magnesium phyllosilicates in stratigraphic context. Expanding on the discoveries of OMEGA, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard the Mars Reconnaissance Orbiter (MRO) has found more spatially widespread and mineralogically diverse alteration minerals than previously realized, which represent multiple aqueous environments. Using CRISM near‐infrared spectral data, we detail the basis for identification of iron and magnesium smectites (including both nontronite and more Mg‐rich varieties), chlorite, prehnite, serpentine, kaolinite, potassium mica (illite or muscovite), hydrated (opaline) silica, the sodium zeolite analcime, and magnesium carbonate. The detection of serpentine and analcime on Mars is reported here for the first time. We detail the geomorphic context of these minerals using data from high‐resolution imagers onboard MRO in conjunction with CRISM. We find that the distribution of alteration minerals is not homogeneous; rather, they occur in provinces with distinctive assemblages of alteration minerals. Key findings are (1) a distinctive stratigraphy, in and around the Nili Fossae, of kaolinite and magnesium carbonate in bedrock units always overlying Fe/Mg smectites and (2) evidence for mineral phases and assemblages indicative of low‐grade metamorphic or hydrothermal aqueous alteration in cratered terrains. The alteration minerals around the Nili Fossae are more typical of those resulting from neutral to alkaline conditions rather than acidic conditions, which appear to have dominated much of Mars. Moreover, the mineralogic diversity and geologic context of alteration minerals found in the region around the Nili Fossae indicates several episodes of aqueous activity in multiple distinct environments.

Observations by the Compact Reconnaissance Imaging Spectrometer (CRISM) onboard the Mars Reconnaissance Orbiter (MRO) over the range 440–2920 nm of the very dusty Martian atmosphere of the 2007 planet‐encircling dust event are combined with those made by both Mars Exploration Rovers (MERs) to better characterize the single scattering albedo (ω0) of Martian dust aerosols. Using the diagnostic geometry of the CRISM emission phase function (EPF) sequences and the “ground truth” connection provided at both MER locations allows one to more effectively isolate the single scattering albedo (ω0). This approach eliminates a significant portion of the type of uncertainty involved in many of the earlier radiative transfer analyses. Furthermore, the use of a “first principles” or microphysical representation of the aerosol scattering properties offers a direct path to produce a set of complex refractive indices (m = n + ik) that are consistent with the retrieved ω0 values. We consider a family of effective particle radii: 1.2, 1.4, 1.6, and 1.8 μm. The resulting set of model data comparisons, ω0, and m are presented along with an assessment of potential sources of error and uncertainty. We discuss our results within the context of previous work, including the apparent dichotomy of the literature values: “dark” (solar band ω0 = 0.89–0.90) and “bright” (solar band ω0 = 0.92–0.94). Previous work suggests that a mean radius of 1.8 μm is representative for the conditions sampled by the CRISM observations. Using the m for this case and a smaller effective particle radius more appropriate for diffuse dust conditions (1.4 μm), we examine EPF‐derived optical depths relative to the MER 880 nm optical depths. Finally, we explore the potential impact of the resulting brighter solar band ω0 of 0.94 to atmospheric temperatures in the planetary boundary layer.

Juventae Chasma contains four light‐toned sulfate‐bearing mounds (denoted here as A–D from west to east) inside the trough, mafic outcrops at the base of the mounds and in the wall rock, and light‐toned layered deposits of opal and ferric sulfates on the plateau. Hyperspectral visible/near‐infrared Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectra were used to identify monohydrated and polyhydrated sulfate (PHS) outcrops of layered material on the bright mounds. Most of the monohydrated sulfate signatures closely resemble those of szomolnokite (FeSO4·H2O), characterized by a water band near 2.08 μm, while some areas exhibit spectral features more similar to those of kieserite (MgSO4·H2O), with a band centered closer to 2.13 μm. The largest PHS outcrops occur on the top of mound B, and their spectral features are most consistent with ferricopiapite, melanterite, and starkeyite, but a specific mineral cannot be uniquely identified at this time. Coordinated analyses of CRISM maps, Mars Orbiter Laser Altimeter elevations, and High Resolution Imaging Science Experiment images suggest that mounds A and B may have formed together and then eroded into separate mounds, while mounds C and D likely formed separately. Mafic minerals (low‐Ca pyroxene, high‐Ca pyroxene, and olivine) are observed in large ∼2–10 km wide outcrops in the wall rock and in smaller outcrops ∼50–500 m across at the floor of the canyon. Most of the wall rock is covered by at least a thin layer of dust and does not exhibit strong features characteristic of these minerals. The plateau region northwest of Juventae Chasma is characterized by an abundance of light‐toned layered deposits. One region contains two spectrally unique phases exhibiting a highly stratified, terraced pattern. CRISM spectra of one unit eroded into swirling patterns with arc‐like ridges exhibit a narrow 2.23‐μm band assigned to hydroxylated ferric sulfate. A thin layer of a fractured material bearing an opaline silica phase is observed at the contact between the older plateau unit and the younger hydroxylated ferric sulfate‐bearing light‐toned layered deposits. Hydrothermal processes may have produced an acidic environment that fostered formation of the hydrated silica and hydroxylated ferric sulfate units.

The part of the Compact Reconnaissance Imaging Spectrometer (CRISM) for Mars investigation conducted during the Mars Reconnaissance Orbiter's (MRO's) primary science phase was a comprehensive investigation of past aqueous environments, structure of the planet's crust, past climate, and current meteorology. The measurements to implement this investigation include over 9500 targeted observations of surface features taken at spatial resolutions of better than 40 m/pixel, monitoring of seasonal variations in atmospheric aerosols and trace gases, and acquisition of a 200 m/pixel map covering over 55% of Mars in 72 selected wavelengths under conditions of relatively low atmospheric opacity. Key results from these data include recognition of a diversity of aqueous mineral‐containing deposits, discovery of a widespread distribution of phyllosilicates in early to middle Noachian units, the first definitive detection of carbonates in bedrock, new constraints on the sequence of events that formed Hesperian‐aged, sulfate‐rich layered deposits, characterization of seasonal polar processes, and monitoring of the 2007 global dust event. Here we describe CRISM's science investigations during the Primary Science Phase, the data sets that were collected and their calibration and uncertainties, and how they have been processed and made available to the scientific community. We also describe the ongoing investigation during MRO's extended science phase.

Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high‐resolution data from the Mars Reconnaissance Orbiter in the well‐exposed Noachian crust surrounding the Isidis basin. We focus on data from the Compact Reconnaissance Imaging Spectrometer for Mars as well as imaging data sets from High Resolution Imagine Science Experiment and Context Imager. These data show the lowermost unit of Noachian crust in this region is a complex, brecciated unit of diverse compositions. Breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of Fe/Mg‐phyllosilicates are commonly observed. In regions of good exposure, layered or banded phyllosilicate‐bearing breccia rocks are observed suggestive of pre‐Isidis sedimentary deposits. In places, the phyllosilicate‐bearing material appears as a matrix surrounding mafic blocks, and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin‐scale ejecta. These materials likely include both pre‐Isidis basement rocks as well as the brecciated products of the Isidis basin–forming event at 3.9 Ga. A banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of Nili Fossae to the southern edge of the Isidis basin. This olivine‐mafic cap combination superimposes the phyllosilicate‐bearing basement rocks and distinctly conforms to the underlying basement topography. This may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology. We interpret the draping, superposed olivine‐mafic cap combination to be impact melt from the Isidis basin–forming event. While some distinct post‐Isidis alteration is evident (carbonate, kaolinite, and serpentine), the persistence of olivine from the time of Isidis basin suggests that large‐scale aqueous alteration processes had ceased by the time this unit was emplaced.

Mawrth Vallis contains one of the largest exposures of phyllosilicates on Mars. Nontronite, montmorillonite, kaolinite, and hydrated silica have been identified throughout the region using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). In addition, saponite has been identified in one observation within a crater. These individual minerals are identified and distinguished by features at 1.38–1.42, ∼1.91, and 2.17–2.41 μm. There are two main phyllosilicate units in the Mawrth Vallis region. The lowermost unit is nontronite bearing, unconformably overlain by an Al‐phyllosilicate unit containing montmorillonite plus hydrated silica, with a thin layer of kaolinite plus hydrated silica at the top of the unit. These two units are draped by a spectrally unremarkable capping unit. Smectites generally form in neutral to alkaline environments, while kaolinite and hydrated silica typically form in slightly acidic conditions; thus, the observed phyllosilicates may reflect a change in aqueous chemistry. Spectra retrieved near the boundary between the nontronite and Al‐phyllosilicate units exhibit a strong positive slope from 1 to 2 μm, likely from a ferrous component within the rock. This ferrous component indicates either rapid deposition in an oxidizing environment or reducing conditions. Formation of each of the phyllosilicate minerals identified requires liquid water, thus indicating a regional wet period in the Noachian when these units formed. The two main phyllosilicate units may be extensive layers of altered volcanic ash. Other potential formational processes include sediment deposition into a marine or lacustrine basin or pedogenesis.

We report on mapping of the south polar region of Mars using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument. Our observations have led to the following discoveries: (1) Water ice is present in the form of pole‐circling clouds originating from the circum‐Hellas region, beginning prior to Ls = 162 and diminishing markedly at Ls = 200–204. (2) It has previously been inferred by thermal infrared observations by Titus et al. (2003) and CO2‐H2O mixture spectral models by Langevin et al. (2007) that surface water ice was present in the cryptic region in the final stages of sublimation. The high resolution of CRISM has revealed regions where only water ice is present (not a CO2‐H2O ice mixture). This water ice disappears completely by Ls = 252 and may be the source of water vapor observed by CRISM in southern latitudes between Ls = 240–260 by M. Smith et al. (2009). (3) We have estimated surface CO2 ice grain size distributions for the South Pole Residual Cap (SPRC) and the seasonal CO2 ice cap that covers it throughout summer spring and summer. Our analysis suggests that grain sizes peak at Ls = 191–199 with an apparent grain size of ∼7 ± 1 cm. By the end of the summer period our analysis demonstrates minimum apparent grain sizes of ∼5 ± 1 mm predominate in the SPRC. (4) Fine‐grained CO2 ice condenses from Ls = 0–40 and extends symmetrically away from the geographic pole, extending beyond 80°S by Ls = 4–10. No evidence for unusual CO2 depositional processes in the cryptic region is observed up to Ls = 16.

The combination of ground observations from the Mars Phoenix Lander and orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) provided a detailed view of the formation of late summer surface water ice at the landing site and surrounding regions. CRISM observations of the landing site during and immediately after Phoenix operations were analyzed to track the seasonal and diurnal ice cycles during the late spring to late summer, and a nonlinear mixing model was used to estimate grain sizes and relative abundances of water ice and dust. The surface around the Phoenix landing site was ice‐free from late spring through midsummer, although transient patches of mobile ices were observed in an 85 m diameter crater to the northeast of the landing site. At the ∼10 km diameter Heimdal Crater, located ∼10 km east of the landing site, permanent patches of water ice were observed to brighten during the late spring and darken during the summer, possibly as fine‐grained water ice that was cold trapped onto the ice during late spring sintered into larger grains or finally sublimated, exposing larger‐grained ice. CRISM spectra first show evidence of widespread ice during the night at solar longitude (Ls) ∼ 109°, ∼9 sols before Phoenix's Surface Stereo Imager detected it. CRISM spectra first show evidence of afternoon surface ice and water ice clouds after Ls ∼ 155°, after Phoenix operations ended.

The Mars Odyssey Thermal Emission Imaging System (THEMIS) has discovered water ice exposed near the edge of Mars' southern perennial polar cap. The surface H2Oice was first observed by THEMIS as a region that was cooler than expected for dry soil at that latitude during the summer season. Diurnal and seasonal temperature trends derived from Mars Global Surveyor Thermal Emission Spectrometer observations indicate that there is H2Oice at the surface. Viking observations, and the few other relevant THEMIS observations, indicate that surface H2Oice may be widespread around and under the perennial CO2cap.