The Perseverance rover landed in Jezero crater on Mars, which once contained a lake of liquid water. We report the rock properties encountered by Perseverance during a 10-kilometer traverse extending over 400 meters in elevation, from beneath Jezero's western sedimentary fan to the upper crater rim. These rocks consist of coarse-grained olivine, magnesium and iron carbonates, silica, and phyllosilicates, including some of the oldest materials exposed within Jezero. We infer that these rocks formed by olivine accumulation in an igneous system of layered intrusions, followed by exposure to water and carbon dioxide, which caused extensive carbonation of the silicate minerals. Aqueous alteration was more pronounced at lower elevations. Higher-elevation exposures on the crater rim appear similar to olivine-rich rocks distributed over the wider Nili Fossae region.

We report the in situ detection of amorphous hydrated silica in the Bills Bay abrasion patch, located in the eastern portion of the Margin Unit between the rim of Jezero crater and the western delta. Here, hydrated silica co-occurs with olivine, Fe-Mg carbonates, secondary Fe-Mg silicates, and hydrated Mg-sulfate as determined by UV Raman (SHERLOC) and X-ray fluorescence (PIXL) spectrometers onboard the Perseverance rover. Almost pure hydrated silica fills the intergranular space between olivine and carbonate-bearing domains. We performed Raman analysis of terrestrial opals with various crystallinities including opal-AN, AG, CT, and C. We found that the Si-O symmetric stretching Raman band at similar to 800 cm-1 is sensitive to opal crystallinity, yet insensitive to ambient temperature (at similar to 77-293 K) and silica hydration. We identified the crystal structure of the Bills Bay Hydrated Silica (BBHS) as opal-A. Furthermore, we developed a Raman methodology to quantify opal-A hydration. We found that the total amount of hydration in the BBHS phases was 1.7 +/- 0.2 wt. %. Most of this hydration, 1.5 +/- 0.2 wt. %, reflects the presence of silanol groups. Our analysis revealed that the Raman spectrum of BBHS closely resembles that of opal-A that has lost most of its molecular water. The composition and textures of the Bills Bay abrasion indicate that BBHS is derived from olivine carbonation. Opal-A is the only silica polymorph identified in the SHERLOC data. We hypothesized that silica precipitation occurred, either during the late stages of a major carbonation event or during a brief, subsequent aqueous alteration event unrelated to carbonation.

Investigating sedimentary carbonate phases in situ is a primary objective of Mars exploration. Such mineral phases commonly precipitate from surficial waters or near-surface diagenetic fluids, and therefore their presence can constrain past aqueous conditions, have the potential to preserve biosignatures, and may be a mineralogical record of the ancient CO2-rich atmosphere. Jezero crater, the field site for NASA's Mars 2020 Perseverance rover, has experienced multiple periods of aqueous activity and has crater-rim-margin carbonate mineralization evident in orbital spectral data. Here, we report on two new carbonate-bearing sedimentary rocks identified in data collected by the Perseverance rover in the lower portion of the Jezero western sedimentary fan. This study integrates multiple image datasets at these previously unrecognized carbonate localities, Rockytop and Jenkins Gap, to investigate their depositional setting. Differences in their sedimentary attributes and geologic context indicate distinct conditions of carbonate formation that are likely linked to the former lake in Jezero crater. We find that the Rockytop outcrop, comprised of alternating fine gravel and medium sandstone couplets, has carbonate present in detrital grains as well as in the matrix. We interpret these couplets as event beds formed via sedimentary gravity flows. In contrast, the second site has carbonate-encrusted gravels in an unsorted conglomerate that are texturally similar to carbonate cementation in near-shore lacustrine settings (‘tufas’). Both carbonate rocks were apparently deposited during the lacustrine period in Jezero crater, but may not be contemporaneous. We also present an alternate model with the sediment in upper Rockytop deposited in an alluvial/fluvial setting with ambiguous timing. Plain language summary Instruments on spacecraft orbiting or roving Mars can detect rock compositions that are linked to past environmental conditions. Carbonate minerals, in particular, commonly form in near-surface environments and can preserve biosignatures, if present. One of the main reasons the Jezero crater is the field site for NASA's Mars 2020 rover mission is because carbonate mineral signatures defined from orbit are correlated with the hypothesized ancient lake shoreline. Rover observations discovered carbonate mineral phases at two sites in the lower Jezero sedimentary fan that are not detectable in orbital spectral data. At these sites, we found evidence that carbonate is linked to the former lake in Jezero crater. Carbonate precipitation occurred in lake and/or river settings. This study confirms additional habitable settings with biosignature preservation potential for samples collected by the Perseverance rover.

Using a Raman spectrometer onboard the Perseverance rover, we report the heterogeneous distribution of organic carbon within mudstones located in an ancient river valley on Mars. Measurements of two mudstones show hundreds of organic detections, making this the most robust organic detection in Jezero crater thus far, and, to our knowledge, the only detection of macromolecular carbon on a natural rock surface on Mars. Spectra of the interior of one rock reveal an association of organics with secondary carbonate and sulfate minerals, whereas another rock exhibits an association of organics with primary silicate-dominated matrix. Although in situ Raman analyses cannot determine whether these organics denote abiotic or biotic sources, the organic association with both depositional and diagenetic minerals and the detection of organics on the martian surface suggests that the organics observed ubiquitously at the Bright Angel outcrop may be resistant to radiation and oxidation or have been relatively recently exposed.

BACKGROUND:The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument on NASA's Perseverance rover is a deep ultraviolet Raman and fluorescence instrument used for organic and mineral mapping of the Martian surface. Flight instrument design and operational constraints lead to observations with low signal Raman features that must be statistically differentiated from measurement noise. There are many methods to calculate signal-to-noise ratios (SNR) in the Raman literature and we find that these are not equivalent. Thus, there is a need to 1) understand the differences and assumptions within SNR calculations, 2) aid in the comparison of SNR values across literature, and 3) identify SNR calculation methods that optimize limit-of-detection (LOD) based on the instrument characteristics. RESULT:We quantitatively compare methods in which signal-to-noise ratios (SNR) are calculated in Raman spectroscopy. Methods are separated into two broad categories, multi-pixel methods that utilize information across the full Raman bandwidth and single-pixel methods that use only the center pixel in the Raman band. We compare three SNR calculation methods on a standardized SHERLOC data set and show that multi-pixel methods detect spectral bands prior to single-pixel methods. This occurs because single-pixel methods only include signal from one pixel, ignoring the remaining signal across the bandwidth. While the manuscript focuses on Raman spectroscopy for application to SHERLOC data, the SNR calculation methodology can be utilized by any technique that reports spectral data. SIGNIFICANCE:This work is the first to report significant differences between methods of calculating spectroscopic SNR. This manuscript is of broad application with at least 3 points of major impact: 1) different SNR calculation methods are not equivalent and cannot be compared across literature, 2) multi-pixel SNR methods include signal from across the entire Raman bandwidth, improving the assessment of spectral features compared to single-pixel methods, and 3) we confirm a SHERLOC signal previously interpreted as the first Raman detection of organic carbon on the martian surface.

The NASA Mars 2020 mission Perseverance rover carries a piece of Martian meteorite Sayh al Uhaymir (SaU) 008 as part of the calibration payload for the SHERLOC science instrument. We report SHERLOC observations of the SaU 008 flight piece over the first 1,000 sols of the mission and compare them to measurements done prior to launch, showing consistent detection of the same deep‐ultraviolet (DUV) Raman and fluorescence signatures in the same locations. Co‐located X‐ray fluorescence (XRF) and DUV mapping of a reference SaU 008 piece on Earth confirm that the meteorite is comprised of an igneous mineral matrix consistent with shergottite, rich in olivine, maskelynite, and Fe‐Mg pyroxenes detectable by SHERLOC. Terrestrial weathering features consist of fractures and vugs filled with Ca‐carbonate. Fluorescence mapping reveals two major signatures: (a) broad‐spectrum fluorescence present throughout the igneous matrix but strongest in weathering features, attributed to organic material, and (b) narrow‐band 340 nm fluorescence spatially associated with ∼48 ppm cerium in <100 μm Ca‐phosphate grains. Raman revealed organic material in both the igneous matrix and terrestrial carbonate in the form of macromolecular carbon (MMC) with defect and graphitic bands at ∼1,380 and ∼1,600 cm −1 respectively. Raman band parameters suggest that MMC associated with terrestrial weathering is less thermally mature, most likely the result of chemical alteration after landing on Earth. This study serves as a demonstration of SHERLOC's capabilities when supported by co‐located XRF data from PIXL and suggests that SHERLOC can detect Ce in phosphate minerals at concentrations as low as 4 ppm.

The Mars 2020 Perseverance rover has examined and sampled sulfate-rich clastic rocks from the Hogwallow Flats member at Hawksbill Gap and the Yori Pass member at Cape Nukshak. Both strata are located on the Jezero crater western fan front, are lithologically and stratigraphically similar, and have been assigned to the Shenandoah formation. In situ analyses demonstrate that these are fine-grained sandstones composed of phyllosilicates, hematite, Ca-sulfates, Fe-Mg-sulfates, ferric sulfates, and possibly chloride salts. Sulfate minerals are found both as depositional grains and diagenetic features, including intergranular cement and vein- and vug-cements. Here, we describe the possibility of various sulfate phases to preserve potential biosignatures and the record of paleoenvironmental conditions in fluid and solid inclusions, based on findings from analog sulfate-rich rocks on Earth. The samples collected from these outcrops, Hazeltop and Bearwallow from Hogwallow Flats, and Kukaklek from Yori Pass, should be examined for such potential biosignatures and environmental indicators upon return to Earth.

The Mars 2020 Perseverance rover is equipped with 23 cameras that aid in science operations and investigations [1]. The cameras on Perseverance image from the scale of tens of meters down to tens of microns, enabling detailed visual analysis of the martian surface across spatial scales. Some of these cameras are co-boresighted to spectrometers, allowing for the acquisition of spatially resolved compositional data. Integrating images from multiple different cameras is a challenge due to differences such as angle of acquisition, illumination, resolution, and pixel scale. However, combining these data enables a more comprehensive understanding of each target of interest by utilizing the complementary advantages of each imager or instrument. Here, we present two case studies that highlight the utility of computer vision to address science needs and improve science return of in situ analyses. In the first, we apply keypoint detection and matching to align images from two mapping spectrometers, thus allowing for complementary analysis with Raman spectroscopy and X-ray Fluorescence spectroscopy. We extend this case study by aligning images from two different cameras to yield a high-resolution blended composite that captures both texture and color information. In the second case study, we apply fast color transfer algorithms to adjust images taken by the same camera of many different rock targets, thus enabling a better comparison of textures and colors irrespective of lighting conditions during acquisition. We further apply this approach to match colors across images taken from different cameras to evaluate the similarity of the collected sample to the proxy abrasion patch on the parent rock.

The Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC) instrument on the Mars Perseverance Rover robotic arm is a deep UV Raman and fluorescence mapping spectrometer, generating rich hyperspectral datasets co-located with high resolution context images. SHERLOC is equipped with a suite of on-board data processing algorithms, which can be employed to identify regions of interest within a SHERLOC hyperspectral map for immediate follow-up observations of the most astrobiologically interesting targets. Autonomous on-board target selection improves operation efficiency by reducing the number of human decision loops, and potentially decreases the amount of time an abraded surface is exposed to solar UV radiation and arid Martian conditions before SHERLOC makes informed, high resolution measurements, preserving volatiles and potential organics from alteration.In this manuscript, we discuss each of SHERLOC’s on-board data processing algorithms, ground testing, the potential for improved science return, and how surface operations benefit from the implementation of on-board data processing.

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.

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.

The Mars 2020 Perseverance rover has explored fluvio-lacustrine sedimentary rocks within Jezero crater. Prior work showed that igneous crater floor S & eacute;& iacute;tah and M & aacute;az formations have mafic mineralogy with alteration phases that indicate multiple episodes of aqueous alteration. In this work, we extend the analyses of hydration to targets in the Jezero western fan delta, using data from the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) Raman spectrometer. Spectral features, for example, sulfate and hydration peak positions and shapes, vary within, and across the crater floor and western fan. The proportion of targets with hydration associated with sulfates was approximately equal in the crater floor and the western fan. All hydrated targets in the crater floor and upper fan showed bimodal hydration peaks at similar to 3,200 and similar to 3,400 cm(-1). The sulfate symmetric stretch at similar to 1,000 cm(-1) coupled with a hydration peak at similar to 3,400 cm(-1) indicate that MgSO4nH(2)O (2 < n <= 5) is a likely hydration carrier phase in all units, perhaps paired with low-hydration (n <= 1) amorphous Mg-sulfates, indicated by the similar to 3,200 cm(-1) peak. Low-hydration MgSO4nH(2)O (n = 1-2) are more prevalent in the fan, and hydrated targets in the fan front only had one peak at similar to 3,400 cm(-1). While anhydrite co-occurs with hydrated Mg-sulfates in the crater floor and fan front, hydrated Ca-sulfates are observed instead at the top of the upper fan. Collectively, the data imply aqueous deposition of sediments with formation of salts from high ionic strength fluids and subsequent aridity to preserve the observed hydration states.

Abstract The Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon.

Sulfur plays a major role in martian geochemistry and sulfate minerals are important repositories of water. However, their hydration states on Mars are poorly constrained. Therefore, understanding the hydration and distribution of sulfate minerals on Mars is important for understanding its geologic, hydrologic, and atmospheric evolution as well as its habitability potential. NASA's Perseverance rover is currently exploring the Noachian-age Jezero crater, which hosts a fan-delta system associated with a paleolake. The crater floor includes two igneous units (the Seitah and Maaz formations), both of which contain evidence of later alteration by fluids including sulfate minerals. Results from the rover instruments Scanning Habitable Environments with Raman and Luminescence for Organics and Chemistry and Planetary Instrument for X-ray Lithochemistry reveal the presence of a mix of crystalline and amorphous hydrated Mg-sulfate minerals (both MgSO4 center dot[3-5]H2O and possible MgSO4 center dot H2O), and anhydrous Ca-sulfate minerals. The sulfate phases within each outcrop may have formed from single or multiple episodes of water activity, although several depositional events seem likely for the different units in the crater floor. Textural and chemical evidence suggest that the sulfate minerals most likely precipitated from a low temperature sulfate-rich fluid of moderate pH. The identification of approximately four waters puts a lower constraint on the hydration state of sulfate minerals in the shallow subsurface, which has implications for the martian hydrological budget. These sulfate minerals are key samples for future Mars sample return. The history of water on Mars is a puzzle that is of interest to scientists as well as the general public. Mars currently has water in the form of ice at the poles, trace amounts of gas in the atmosphere, and an unknown amount beneath the surface as ground water, bound in minerals, and in ice. However, there is strong evidence that ancient Mars may have had long-lived streams, rivers, and lakes. There is still much to learn about what Mars was like and how it transformed over time. One approach is to study the inventory of water at different times. In this work, we report the presence of hydrated magnesium sulfate (similar to Epsom salts) and dehydrated calcium sulfate that were formed by water flowing through cracks in volcanic rocks at the bottom of the 3.8-billion-year-old Jezero crater. These hydrated minerals trap water within themselves and record the history of how and when they formed. Returning samples of these minerals to Earth would allow researchers to explore the history of Mars' water and climate, and possibly evidence of ancient life with the most sensitive instruments possible. Sulfate phases detected by Scanning Habitable Environments with Raman and Luminescence for Organics and Chemistry and PIXL in igneous units consists of crystalline/amorphous Mg-sulfate minerals with 3-5 waters and anhydrous Ca-sulfate minerals Hydration of sulfate minerals sets a lower constraint on how much subsurface water is stored in sulfate minerals The sulfate minerals of Jezero crater floor were deposited in moderate pH, likely at low temperature, and during several episodes

In this work, we derive a simple method for calibrating Raman bandwidths for the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument onboard NASA's Perseverance rover. Raman bandwidths and shapes reported by an instrument contain contributions from both the intrinsic Raman band (IRB) and instrumental artifacts. To directly correlate bandwidth to sample properties and to compare bandwidths across instruments, the IRB width needs to be separated from instrumental effects. Here, we use the ubiquitous bandwidth calibration method of modeling the observed Raman bands as a convolution of a Lorentzian IRB and a Gaussian instrument slit function. Using calibration target data, we calculate that SHERLOC has a slit function width of 34.1 cm(-1). With a measure of the instrument slit function, we can deconvolve the IRB from the observed band, providing the width of the Raman band unobscured by instrumental artifact. We present the correlation between observed Raman bandwidth and intrinsic Raman bandwidth in table form for the quick estimation of SHERLOC Raman intrinsic bandwidths. We discuss the limitations of using this model to calibrate Raman bandwidth and derive a quantitative method for calculating the errors associated with the calibration. We demonstrate the utility of this method of bandwidth calibration by examining the intrinsic bandwidths of SHERLOC sulfate spectra and by modeling the SHERLOC spectrum of olivine.

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 meteorites 1 and at Gale crater, Mars 2 – 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 sources 1 , 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.

PARSEC (Payload Anchoring Robotic System for the Exploration of Cliffs) is an autonomy-equipped aerial manipulator that can deploy self-anchoring payloads on rocky vertical surfaces. It consists of a hexacopter and a two Degrees of Freedom (2 DoF) mass balancing manipulator, which can autonomously deploy a self-anchoring payload from its custom end-effector. The payload anchors itself via an actuated microspine gripper. Payload sensor data is wirelessly transmitted to the primary vehicle during and after deployment. A novel state machine controls the four-stage PARSEC deployment process. First, the rotorcraft brings the payload into contact with the surface and applies a constant 6 N normal force through a feedback control loop to preload the payload microspine gripper. Second, while the rotorcraft maintains the constant normal force, the gripper is commanded to close until engagement with the surface is confirmed through the current feedback sensing. Then, the aerial manipulator pulls with 5 N force on the anchored payload to ensure a secure grip before releasing the package and flying away. We present experimental validation of a successful deployment of a 430 g payload on a vertical vesicular basalt surface.

Planetary caves are desirable environments for the search for biosignatures corresponding to extant or extinct extraterrestrial life due to the protection they offer from surface-level solar radiation and ionizing particles. Near-infrared (NIR) reflectance spectroscopy is one of a multitude of techniques that, when taken together, can provide a comprehensive understanding of the geomicrobiology in planetary subsurface regions. To that end, we developed two portable NIR spectrometers that employ acousto-optic tunable filters and demonstrated them in three geochemically distinct cave environments. The instruments were deployed both as stand-alone spectrometers positioned against the targets manually and as a component of an instrument payload mounted on a quadruped robot capable of vertical excursions of several meters. In situ measurements of calcium carbonates, sulfates, metal oxides, and microbial colonies and mats revealed spectral signatures that enable a distinction between the targets of interest and the underlying substrates. The ruggedness and portability of the instruments, and their low size, weight, and power, spectral agility, and active illumination make AOTF-based spectrometers ideally suited for studies of planetary caves.