Gossans are formed through the oxidation of sulfide ore deposits by fluids, such as meteoric water or hydrothermal solutions, leading to locally acidic conditions. In permafrost regions, gossans undergo seasonal chemical weathering after their initial formation (reactive gossans), potentially providing a sustained energy source for microbial activity. Arctic gossans are therefore considered valuable analogs for Martian paleo-hydrothermal systems and promising astrobiological targets. While hundreds of gossans have been identified in the Arctic, few have been studied in detail and even fewer using rover-compatible remote sensing techniques. This study aims to characterize the morphological profile of seven Arctic gossans located at Expedition Fiord (Axel Heiberg Island, Nunavut), as well as their geochemistry, mineralogy and organic carbon content using X-ray fluorescence, X-ray diffraction (XRD), Visible (VNIR) to thermal infrared (MIR-TIR) reflectance and Raman spectroscopy. Results showed a dominance of silicon, calcium and iron. Mineralogical analyses revealed gypsum and quartz as major phases, with variable amounts of silicates, sulfates, iron sulfides and iron oxyhydroxides. Raman spectroscopy detected organic carbon in most samples, up to 50 cm deep, in various organo-mineral complexes. XRD was the only technique to detect iron sulfides. VNIR-MIR-TIR reflectance and Raman spectroscopy provided mineralogical results consistent with XRD. All gossans displayed classical profiles, with alteration zones overlying primary sulfides, but showed diverse color and compositional stratification patterns. These variations suggest local mechanisms influence mineral and associated organic carbon distribution. Further investigations should focus on better understanding these local variations, which could guide the search for biosignatures in gossan-like features on Mars.

During the NASA Perseverance rover's exploration of the Jezero crater floor, coatings were commonly observed on rocks. These features may record past water-rock-atmosphere interactions on the crater floor, and understanding their origin is important for constraining the timing of potential water activity and habitability at Jezero. Here, we characterize the morphologic, chemical, and spectral properties of the crater floor rock coatings using color images, visible/near-infrared reflectance spectra, and chemical data from the Mastcam-Z and SuperCam instruments. We show that coatings are common and compositionally similar across the crater floor, and consistent with a mixture of dust, fine regolith, sulfates, and ferric oxides indurated as a result of one or more episodes of widespread surface alteration. All coatings exhibit a similar smooth homogenous surface with variable thickness, color, and spatial extent on rocks, likely reflecting variable oxidation and erosional expressions related to formation and/or exposure age. Coatings unconformably overlie eroded natural rock surfaces, suggesting relatively late deposition that may represent one of the last alteration episodes on the Jezero crater floor. While more common at Jezero, these coatings may be consistent with rock coatings previously observed in situ at other landing sites and may be related to duricrust formation, suggesting a global alteration process on Mars that is not unique to Jezero. The Perseverance rover likely sampled these rock coatings on the crater floor and the results from this study could provide important context for future investigations by the Mars Sample Return mission aimed at constraining the geologic and alteration history of Jezero crater.

The establishment of robust meteorite-asteroid links has been a major focus of planetary exploration, and a major driver of asteroid sample return missions. Reflectance spectroscopy has been shown to be a powerful tool for this purpose. For the meteorites dominated by silicate minerals, quantitative analysis of spectral absorption features caused by the Fe2+-bearing minerals (mainly olivine and pyroxene) is a common method to determine mafic silicate mineralogy and end member abundances, and establish the relationship between them and possible parent bodies. In this study, the reflectance spectra of 22 primitive achondrites (acapulcoites, lodranites and winonaites) from NASA RELAB database were analyzed to determine their positions in the plot of the band area ratio (BAR) and 1 mu m band center (Band I center). We found that Band I center and BAR of acapulcoites and lodranites are in roughly the same range. Acapulcoite-lodranite partially overlap with the field of H chondrites in the plot of the BAR and Band I center. This overlap means that spectral calibrations (also referred to as mineralogical formulas) based on the two types of meteorites needs to be applied with caution. The 2 mu m band center of acapulcoite-lodranite is significantly lower than that of H chondrites, which is consistent with the conclusion of previous studies and provides a means to separate these two groups. In addition, the choice of spectral parameter analysis techniques may be a potential error source in similar studies. We provide generalized spectral fields of primitive achondrites in the plot of the BAR and Band I center derived from two widely used technologies.

Abstract Iron oxide-hydroxide minerals in Martian dust provide crucial insights into Mars’ past climate and habitability. Previous studies attributed Mars’ red color to anhydrous hematite formed through recent weathering. Here, we show that poorly crystalline ferrihydrite (Fe5O8H · nH2O) is the dominant iron oxide-bearing phase in Martian dust, based on combined analyses of orbital, in-situ, and laboratory visible near-infrared spectra. Spectroscopic analyses indicate that a hyperfine mixture of ferrihydrite, basalt and sulfate best matches Martian dust observations. Through laboratory experiments and kinetic calculations, we demonstrate that ferrihydrite remains stable under present-day Martian conditions, preserving its poorly crystalline structure. The persistence of ferrihydrite suggests it formed during a cold, wet period on early Mars under oxidative conditions, followed by a transition to the current hyper-arid environment. This finding challenges previous models of continuous dry oxidation and indicates that ancient Mars experienced aqueous alteration before transitioning to its current desert state.

Ceres, the largest object in the asteroid belt, is the only potential ocean world in the inner Solar System. Previous studies identified deposits of aliphatic organics in and around the Ernutet crater, and at small locations at Inamahari and Urvara craters. The origin of organics, either endogenic or exogenic, in these fresh exposures is still under debate. This study addresses the origin of the organics by analyzing their global distribution and geologic context. Our first step involved a global search for organic-rich sites that might have escaped previous detections. We achieved this by using a deep neural network, utilizing spectral redness in the Dawn's Framing Camera multispectral data to identify potential organic-rich sites. The identified sites were further studied by using IR spectrometer data to infer the compositions of materials showing spectral redness. Of the newly identified red-sloped sites, only two can be considered certain to be organic-rich. We also identified sites with spectral redness, but without any signature of organics in their infrared spectra. These sites could be attributed to the aqueous alteration of magnetite into ferric-iron bearing phases. At Ernutet, Inamahari, and Urvara, the organic-rich material is confined to the near surface only. Additionally, the absence of tectonic/volcanic features at these sites makes an endogenic origin questionable. The global rarity of detectable organics also supports this assessment. Consequently, we suggest that organics at these sites were originally delivered by low-velocity, organic-rich impactor(s) from the main belt and subsequently excavated, rather than originating from endogenous processes.

The Perseverance rover has sampled mm-size lithic fragments containing olivine likely from at least two source regions from the surface of an inactive megaripple surface, and fine-grained material from the surface and to a depth of similar to 4-6 cm. Some of the mm-size grains lack a coherent diffraction pattern measured by PIXL, consistent with the presence of poorly ordered secondary phases that have been altered. Analysis of these materials on Earth will allow examination of materials that have experienced aqueous, potentially habitable environments that could contain biosignatures. Fluorescence of three different patterns was detected, consistent with inorganic emissions from silica defects or rare earth elements in certain mineral phases, although organic origin cannot be excluded. Analysis of Autofocus Context Imager and Wide Angle Topographic Sensor for Operations and eNgineering images of the subsurface material and MEDA thermal inertia measurements indicate average grain sizes of similar to 125 and similar to 150 mu m, respectively, for the bulk material within the megaripple. The fine-grained material in the sampling location indicates chemical compositions similar to previously proposed global components as well as airfall dust. In situ and associated atmospheric measurements provide evidence of recent processes likely including water vapor in soil crust formation. The sampled material will therefore help elucidate the formation of Martian soils; current surface-atmosphere interactions; the composition, shape, and size distribution of dust grains valuable for studies of past and present Martian climate and for assessing potential health and other risks to human missions; and ancient, aqueously altered environments that could have been habitable, and, if Mars contained life, possibly contain biosignatures.

The search for organic molecules on Mars is central to understanding the planet's past habitability and potential for ancient life. Although organic molecules have previously been detected on Mars, their nature, origin and preservation mechanisms remain debated. On the floor of the Jezero crater-an ancient delta-lake system on Mars-the Perseverance rover detected Raman features that may be due to organic compounds spatially associated with sulfates, although their origin is uncertain. Here we report the detection of similar Raman features in the Jezero fan top and attribute them to polycyclic aromatic hydrocarbons based on comparisons with laboratory data. We propose that these polycyclic aromatic hydrocarbons may have formed through endogenous igneous processes and were subsequently preserved by sulfate precipitation. These findings align with previous studies on Martian meteorites and at Gale crater, underscoring the role of sulfates in preserving organic matter on Mars. Returning these samples to Earth would be key to assess their astrobiological relevance.

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.

Introduction: Lunar exploration is driven by a number of science and exploration goals (e.g., LEAG, 2016, 2017) [1]. One is determining the presence of water ice deposits in permanently shadowed regions (PSRs) [e.g., 2-5]. They are of scientific interest because past lunar exospheric conditions may be preserved in the ice [6], as well as for in-situ resource utilization.Multiple lines of evidence indicate that water ice is or may be present within some PSRs [e.g., 2, 6,7]. However, its areal distribution is largely unknown, particularly at sub-km spatial scales. Detecting surficial water ice within these PSRs could be achieved through active reflectance spectroscopy [e.g., 8].The VMMO Remote Sensing Payload: The proposed VMMO mission, which recently completed a CSA-funded Phase 0 and ESA-funded Phase A study, is intended to probe PSRs at spatial scales of metres to tens of metres. Active sensing will be accomplished via a three-band lidar system using wavelengths of 532, 1064, and 1560 nm [9].The selection of these wavelengths was designed to enable discrimination of water ice from mare and highlands. Highland regolith spectra are generally moderately bright in the visible region, flat to red-sloped beyond the visible region, usually with a weak plagioclase feldspar absorption band in the 1300 nm region, and sometimes with weak mafic silicate absorption bands in the 1000 and 2000 nm regions [10] (Figure 1). Mare regolith spectra are darker in the visible region, red-sloped beyond the visible region, and with weak to moderate mafic silicate absorption bands in the 1000 and 2000 nm regions (Figure 2). Water ice spectra are bright in the visible region, with blue sloped spectra beyond this region, and increasingly strong water ice absorption bands in the 1000, 1500, and 2000 nm regions [11] (Figure 3). At the VMMO wavelengths, these types of materials can be discriminated using both absolute reflectance and reflectance ratios for these three wavelengths.However, dust cover, percentage of ice covered by regolith, and regolith: ice ratio, and how dust and ice are mixed together could all influence the efficiency of detecting water ice. We have conducted laboratory experiments to test for how physical properties of ice + powdered lunar rock affect our ability to detect water ice using the three-band lidar system. We considered the following parameters: (1) different water ice: lunar material ratios in both intimate and areal mixtures; (2) local slope; and (3) different thicknesses of dust cover over water ice.Methods: Reflectance spectra (350-2500 nm) were acquired with an ASD Fieldspec Pro HR spectrometer. To simulate a lidar, we used a bifurcated fiber optic bundle, which provided co-aligned incidence and emission (i=e=0°). To measure the effects of local slope on lidar return, the samples were positioned at 10˚, 20˚, 30˚ and 40˚ off normal. All spectra were measured relative to a calibrated Spectralon panel.Results: Ice detection is possible using reflectance spectroscopy at 532, 1064, and 1530 nm for water ice abundances as low as 1 wt.%. We can determine or constrain whether water ice is exposed at the lunar surface, or covered by a thin dust layer. Both absolute and reflectance ratios using all three bands are required to fully detect and discriminate mare, highland, and water ice and to derive water ice surficial abundance.Water ice detection and discrimination is reliant on reflectance of the 1560 nm band, as this is where a strong water ice O-H overtone occurs, and reflectance in this region rapidly decreases with increasing ice abundance. In all cases, lunar regolith spectra are red-sloped (reflectance increasing toward longer wavelengths), and absolute reflectance varies with factors such as maturity and ilmenite abundance. Detection of water ice will be enhanced by comparing spectra acquired during a scan across a PSR, where mineralogical variations inside and immediately outside a PSR should be similar but vary in temperature [12, 13].Ilmenite detection: VMMO can also operate in passive reflectance mode. A portion of the detector will be equipped with a bandpass filter to measure reflected light in the ultraviolet (~290 nm) region. Ilmenite discrimination is best accomplished using an ultraviolet: visible reflectance ratio [14] (Fig. 4).Summary: VMMO provides an opportunity to search for surficial water ice at high sensitivity and spatial resolution useful for targeting locations for investigation by surface landers with precision guidance capabilities.Acknowledgements: This study has been supported by ESA, CSA, CFI, MRIF, NSERC, and UWinnipeg.References: [1] LEAG, (2016, 2017). https://www.lpi.usra.edu/leag/. [2] Nozette S. et al. (2001) JGR, 106, 23253–23266. [3] Lawrence, D.J. (2011). Nature Geosci., 4, 586-588. [4] Lawrence, D.J. (2017) JGR, 122, 21-52. [5] Lucey, P.G. (2009) Elements, 5, 41-46. [6] Feldman W. C. et al. (2001) JGR, 106, 23231–23251. [7] Colaprete, A., et al. (2010) Science, 330, 463-468. [8] Yoldi Z. et al. (2018) LPSC 49, # 2083. [9] Kruzelecky R. V. et al. (2018) ICES, 227, 1–20. [10] Pieters, C.M. (1986) Rev. Geophys.. 44, 557-578. [11] Clark, R.N. (1981) JGR, 86, 3087-3096. [12] Watson, K., et al. (1961) JGR, 66, 1598–1600. [13] Vasavada, A. R., et al. (1999) Icarus, 141,179–193. [14] Robinson, M.S., et al. (2007) GRL, 34, L13203. [14] C. Pitcher, et al. (2016) ASR, 57(5), 1197–1208. Figure 1. Reflectance spectra of two Apollo 16 highland regolith samples (

OSIRIS-REx is a sample return mission to near-Earth Asteroid (101955) Bennu (Lauretta et al. 2017). The asteroid is spectrally classified as a B-type (Clark et al. 2011), and phyllosilicates similar to those found in carbonaceous chondrites have been detected on its surface (Hamilton et al. 2019). Bennu has a relatively flat (and blue) reflectance spectrum in the 0.4 to 3.7 micron spectral range and has a low albedo of ~4.5% (Golish et al. 2020).Bennu has a rough and rocky surface. Imaging data from the OSIRIS-REx Camera Suite (OCAMS; Rizk et al. 2018) reveals that boulders in the size range from 1 to 10 meters dominate the surface (Lauretta et al. 2019; DellaGiustina and Emery et al. 2019). Observed boulder textures range from smooth to hummocky and breccia-like (Walsh et al. 2019; DellaGiustina and Emery et al. 2019). The smoother rocks appear to be smaller, brighter, and more angular, while the rougher rocks appear to be larger, darker, and highly textured. Because spectral variations on Bennu are subtle and associated with albedo (Clark et al. 2019), the question arises: Could the observed color variations be due to texture variations alone, or are space-weathering variations required to explain the observations? To isolate the spectral effects of texture on the spectral properties of Bennu, we first simulate Bennu’s spectrum using a two-component mixture, then we check to see whether texture changes in this analog can account for the observed color and albedo trends. Simulated Bennu Spectral Analog: We synthesized physical mixtures of saponite (SAP105 with ~25 wt.% dolomite) with two forms of carbon:

Understanding the nature and evolution of near-Earth asteroids (NEAs) are of paramount importance to planetary science1 and security2. So far, three asteroid sample-return missions, Hayabusa, Hayabusa2, and OSIRIS-REx to asteroids have greatly increased our knowledge of several-hundred-meter rubble-pile NEAs. However, limited by ground-based observation spatial resolution, little is known about smaller NEAs. Recently, the China National Space Administration has proposed a new asteroid mission, Tianwen-2, which plans to first return a sample from an Earth quasi-satellite (469219) 2016 HO3 Kamoʻoalewa, and then orbit and characterize an active main-belt asteroid: 311P/PANSTARRS. Here we report that Kamoʻoalewa is an S-type, sub-hundred-meter-sized (69.45 m × 58.49 m × 51.78 m), rapid-rotating (period is 27.37 minutes) NEA developed with grain size < 2 cm regolith. We analyzed telescopic observations of Kamoʻoalewa, whose visible to near-infrared (VIS-NIR) reflectance spectrum shows a 0.984 (+0.003,-0.004) μm absorption center, suggesting that it resembles LL ordinary chondrites in composition. Orbital dynamical calculations show that Kamoʻoalewa holds a 72 ± 5% probability of originating from the inner main belt ν6 secular resonance adjacent to the Flora family. Notably, Kamoʻoalewa exhibits an extremely red (positively steep) VIS-NIR spectral slope, making it a typical space weathering (SW)-matured object. Our spectral model calculations further suggest that the sub-microphase iron content in Kamoʻoalewa’s regolith is 0.29 ± 0.05 wt.% and the SW timescale is ~0.5–1 × 10^8 years. This means that Kamoʻoalewa is indeed a SW-matured object and the separation from its parent body likely took place in the inner main belt long before it evolved into an NEA. We ascribe Kamoʻoalewa’s extremely red spectral slope to the combined effects of SW, YORP spin-up, thermal degradation, low-frequency impacts, and non-rubble pile structure. We further predict that sub-hundred-meter, rapidly spinning silicate-rich NEAs with small perihelion may generally exhibit extremely red spectral slopes and SW-matured surfaces.

.IntroductionNASA’s OSIRIS-REx (Origins, Spectral Interpretations, Resource Identification, and Security–Regolith Explorer) asteroid sample return mission (Lauretta et al., 2017) began operating in proximity to near-Earth asteroid (101955) Bennu in December 2018. Here we present an analysis of the global photometry of Bennu from measurements by the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS; Reuter et al., 2018). This instrument is a point spectrometer with a wedged filter design. OVIRS is used for the spectral characterization of the surface of Bennu, with a field of view of 4 mrad and an effective spectral range from 0.4 to 4.3 μm. Our work focuses on OVIRS data acquired from December 9, 2018, to September 26, 2019.2.DatasetThis study comprises the global observation data from Preliminary Survey and the two sub-phases of Detailed Survey, Baseball Diamond (BBD) and Equatorial Stations (EQ) (campaigns described in Lauretta et al., 2017). We use a total of 299,702 calibrated spots. More details about the data selection and calibration are introduced by Zou et al. (submitted).3.Photometric analysesWe model the scattering properties of the surface of Bennu using the Lommel-Seeliger, Minnaert, McEwen, and Akimov photometric models. The best-fit model is a McEwen model with an exponential phase function and an exponential polynomial partition function. We use this model to correct the OVIRS spectra of Bennu to a standard reference viewing and illumination geometry at visible to infrared wavelengths for the purposes of global spectral mapping (Figure 1). We derive a bolometric Bond albedo map in which Bennu’s surface values range from 0.021 to 0.027. We find a phase reddening effect of 1.4±0.3 × 10−4 μm−1deg−1 across the wavelength range 0.48 to 2.5 μm, and our model is effective at removing this phase reddening.We compare our OVIRS results to Golish et al. (2020)’s report on the global photometry of Bennu, based on imaging data from the OSIRIS-REx Camera Suite (OCAMS; Rizk et al., 2018). We also compare the results to ground observation and other minor planets including Ryugu.Acknowledgements: This material is based upon work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. We are grateful to the entire OSIRIS-REx Team for making the encounter with Bennu possible and the exploration highly successful. X.-D. Zou and J.-Y. Li also acknowledge partial support from the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (Grant NNH16ZDA001N), SSERVI-TREX to the Planetary Science Institute. M. A. Barucci acknowledges funding support from CNES. ReferencesBennett, C.A., et al. 2020. A high-resolution global basemap of (101955) Bennu. Icarus. doi: 10.1016/j.icarus.2020.113690.Ernst et al., 2018, The Small Body Mapping Tool (SBMT) for Accessing, Visualizing, and Analyzing Spacecraft Data in Three Dimensions, LPSC 49, abstract no. 1043.Golish, D.R., et al. 2020. Disk-resolved photometric modeling and properties of asteroid (101955) Bennu. Icarus, doi:10.1016/j.icarus.2020.113724.Lauretta, D.S., et al. 2017. OSIRIS-REx: sample return from asteroid (101955) Bennu. Space Science Reviews 212(1-2):925-984.Reuter, D.C., et al. 2018. The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): spectral maps of the asteroid Bennu. Space Science Reviews 214(2):54.Rizk, B., et al. 2018. OCAMS: the OSIRIS-REx Camera Suite. Space Science Reviews 214(1):26.Zou et al. (submitted). Photometry of asteroid (101955) Bennu with OVIRS on OSIRIS-REx. Icarus.Figure 1. A global 3D facet-based map of the photometrically corrected (to 30°, 0°, 30°) OVIRS spots at a wavelength of 0.55 μm. The data are overlain on the OCAMS imaging basemap (Bennett et al., 2020), as viewed in the Small Body Mapping Tool (Ernst et al. 2018). Input spectra were obtained during Detailed Survey EQ3.

We report a comprehensive study of the ungrouped type 2 carbonaceous chondrite, Tarda, which fell in Morocco in 2020. This meteorite exhibits substantial similarities to Tagish Lake, Wisconsin Range 91600, and Meteorite Hills 00432, which are generally considered to have originated from a D-type asteroid(s). We constrain the compositions and petrologies of the materials present in a potential sample of a D-type asteroid by reporting the petrography, bulk chemical compositions, bulk H, C, N, Cr, and Ti isotopic compositions, reflectance spectra, and in situ chemical compositions of metals, sulfides, carbonates, and FeO-poor and FeO-rich chondrule silicates of Tarda. We also present new data for Tagish Lake. We then compare Tarda with the other Tagish Lake-like meteorites.Tarda and Tagish Lake appear to be from the same parent body, as demonstrated by their similar petrologies (modal abundances, chondrule sizes), mineral compositions, bulk chemical and isotopic compositions, and reflectance spectra. While the two other Tagish Lake-like meteorites, Wisconsin Range 91600 and Meteorite Hills 00432, show some affinities to Tagish Lake and Tarda, they also share similar characteristics to the Mighei-like carbonaceous (CM) chondrites, warranting further study. Similarities in reflectance spectra suggest that P-type asteroids 65 Cybele and 76 Freia are potential parent bodies of Tarda and the Tagish Lake-like meteorites, or at least have similar surface materials. Since upcoming spacecraft missions will spectrally survey D-type, P-type, and C-type Trojan asteroids (NASA's Lucy) and spectrally study and return samples from Mars' moon Phobos (JAXA's Martian Moons eXploration mission), which is spectrally similar to D-type asteroids, these meteorites are of substantial scientific interest. Furthermore, since Tarda closely spectrally matches P-type asteroids (but compositionally matches the D-type asteroid like Tagish Lake meteorite), P-type and D-type asteroids may represent fragments of the same or similar parent bodies.

Carbonaceous chondrites (CCs) are windows into the early Solar System and the histories of their parent bodies. Their infrared spectral signatures are powerful proxies for deciphering their composition and evolution history, but still present formidable challenges in relation to determining the degree of secondary processing such as aqueous alteration and thermal metamorphism via comprehensive data and mid-infrared feature. In our study, we delved into the infrared spectra spanning 1-25 mu m of 17 CCs, with distinct petrological characteristics and varying degrees of alteration. Through this investigation, we uncovered distinct spectral patterns that shed light on the processes of alteration and metamorphism. As aqueous alteration intensifies, two key spectral features, the 3 mu m -region absorption feature associated with OH-bearing minerals and water, and the 6 mu m band indicative of water molecules, both grow in intensity. Simultaneously, their band centers shift towards shorter wavelengths. Moreover, as alteration progresses, a distinctive absorption feature emerges near 2.72 mu m, resembling the OH absorption feature found in serpentine and saponite minerals. Comparison of aqueous alteration to laboratoryheated CCs suggests that the 3 mu m region OH/H2O absorption feature differs between CC heated to less than or more than similar to 300 C-degrees. Further insights are gained by examining the vibrational features of silicate minerals, notably influencing the 10 mu m and 20 mu m regions. The 12.4 mu m /11.4 mu m reflectance ratio diminishes, and the reflectance peak in the 9-14 mu m range shifts towards shorter wavelengths. These changes are attributed to the transformation of anhydrous silicates into phyllosilicates. In the 15-25 mu m region, the influence of thermal metamorphism becomes evident and results in the appearance of more spectral features, the single reflectance peak at 22.1 mu m undergoes a transformation into two distinct peaks at 19 mu m and 25 mu m, which is primarily attributed to the increased presence of anhydrous silicates and olivine recrystallization. These findings offer novel insights into the volatile-rich compositions of C-complex asteroids and the thermal evolution histories of their parent bodies.

Phosphorus is an essential component for life, and in-situ identification of phosphate minerals that formed in aqueous conditions directly contributes toward one of the main goals of the Mars 2020 Perseverance rover: to seek signs of ancient habitable environments. In Jezero crater, proximity science analyses within a conglomerate outcrop, “Onahu” demonstrate the presence of rare Fe3+-bearing phosphate minerals (likely beraunite, metavivianite, ferrolaueite, and/or santabarbaraite) embedded in a carbonate-rich matrix. While Fe-phosphates have been previously inferred on Mars, this work presents the most definitive in-situ identification of martian Fe-phosphate minerals to date, using textural, chemical, spectral, and diffraction analyses of discrete green-blue grains. The Fe-phosphate minerals’ textural context along with comparisons to Earth analogs suggest they likely formed after oxidation of the Fe2+-phosphate vivianite — the most common Fe-phosphate on Earth, often associated with microbial activity and organics. The Fe3+-phosphate assemblage after vivianite, and the presence of two distinct matrix domains in Onahu indicate that the conglomerate and corresponding sample collected by Perseverance (Otis_Peak) preserve a record of evolving habitable paleoenvironmental conditions on Mars. Once returned to Earth, analysis of the Fe-phosphates in the Otis_Peak sample will provide new insights into ancient habitable environments, and, if analogous to terrestrial vivianite-rich environments, potential links with microbial activity.

IntroductionIn almost every planetary surface investigation, the characterization from a camera is a common initial step [1]. Mission Control is developing a science autonomy system called Autonomous Soil Assessment System: Contextualizing Rocks, Anomalies and Terrains in Exploratory Robotic Science (ASAS-CRATERS). It can enable automated surface characterization on planetary missions, which can benefit a wide range of science investigations and rover navigation alike. It can perform terrain classification and novelty detection using convolutional neural networks, and data aggregation to produce relevant data products for supporting science operations. Built on cutting-edge algorithms and off-the-shelf computing components, it offers low-cost ways to speed up tactical decision-making in next-generation commercial lunar missions.Background and MotivationAutonomy in Science OperationsSeveral factors are increasingly driving the need for autonomy in science operations. In traditional Mars rover operations, visual surface characterization and subsequent analysis and decision-making takes place in day-long tactical cycles [2]. Upcoming commercial lunar rover missions will have reduced latency, short lifetimes, and constrained bandwidth shared across several payloads. This will result in a need for rapid tactical decision-making processes with limited data, leaving little time for analysis, target identification, and making decisions. Payload operators may not receive data in a timely fashion, or worse, may not receive some data at all. Autonomous onboard terrain classification offers a way to downlink light-weight data products and reduce the bottleneck in scientific terrain assessment. Autonomous classification and novelty detection increase the chances of detecting novel/sparse features (e.g., lunar outcrop or pyroclasts) that may otherwise be missed or not downlinked when driving and other mission needs are prioritized.Application to Lunar GeologyWhile dedicated science instruments that reveal mineralogical and elemental composition improve our understanding of geological processes, a rover’s navigation sensors can document the morphology, morphometry, and composition of surface materials, regardless of primary investigation goals. High-resolution colour images and 3D data from stereo cameras provide information such as the size-frequency distribution and physical characteristics of craters and rocks, and regolith properties. All this offers valuable insight into the geologic setting. To provide a practical output as a science support tool for several types of missions, a classification scheme is being developed that segments a surface image into geological features that are visually distinct based on morphology, tone, and texture. This will be adapted for specific missions. See Figure 1 for a hand-labelled example.Figure 1: Hand-labelled lunar terrain classification example. Letters indicate crater degradation; P: Pristine; S: Semi-Degraded; G: Ghost. Right: original Yutu-1 image. Credit: CNSA.TechnologyAlgorithms and SoftwareASAS-CRATERS comprises three algorithms. First, the terrain classifier consists of a deep-learning encoder-decoder style network which classifies each image pixel into semantic terrain labels. Second, the novelty detector uses a semi-supervised convolutional neural network architecture with an autoencoder module and a binary classifier that work in series. Third, a data aggregator will combine the outputs on map tiles that are useable by onboard algorithms, lightweight for more efficient downlink, and enables faster backroom analysis and integration into GIS tools. See Figure 2 for a conceptual illustration of how ASAS-CRATERS outputs would be aggregated onto map tiles.Figure 2: Hand-made illustration of aggregating terrain classifier data on orthorectified map tiles.In the near future, additional algorithms will be developed to extend the capabilities of this autonomy system. This primarily includes an autonomous instrument targeting capability so that lunar science instruments, on rovers in particular, can use ASAS-CRATERS to identify and select features for targeting.Sensors and Computing HardwareASAS-CRATERS will be embedded on the Q8S, a high-performance, low-power Xilinx Zynq UltraScale+ System-on-Chip FPGA designed by Xiphos Technologies, which will fly in 2020. The Q8S consumes 3W at minimum and measures 90g and 80x80x22.3mm. Embedded on a flight-ready COTS system, ASAS-CRATERS can be rapidly integrated onto payload suites, rovers, and landers, offering low-cost advanced computing capabilities.Concept of OperationsPrior to deployment on a mission, ASAS-CRATERS’ machine learning algorithms will require training using relevant expert-labelled images from lunar and analogue datasets. Once a mission begins, the algorithms will be updated with images collected in situ. ASAS-CRATERS can then be used to classify terrain and detect features during nominal rover operations. The science team can integrate ASAS-CRATERS data products into their terrain analysis and make decisions on whether specific features merit deeper investigation using onboard instruments.Use Cases and BenefitsASAS-CRATERS can benefit science missions in several ways. First, it can support science operations in tactical cycles. Novelty detection can aid scientists that may miss features or spend valuable time in looking for them. The terrain classifier data products are low-dimensional representations which optimizes downlink. The classification itself can speed up scientific analysis in rapid tactical cycles and this becomes increasingly more useful in complex scenes diverse in mineralogy and lithology. Second, for high-priority features, onboard algorithms can perform instrument targeting and data triage for downlink prioritization. Third, as a semantically useful terrain representation, it can be used by advanced robotics algorithms to enable autonomous and intelligent navigation. Fourth, in human exploration architectures, ASAS-CRATERS can be embedded with crewed systems to provide autonomous capabilities that can support astronauts in geological field excursions.Field Tests and DemonstrationsThe terrain classifier was first developed by Mission Control under the Autonomous Soil Assessment System project [3]. In 2019, it was used to classify eight Mars-relevant terrain types in real-time at ~15 FPS (see Figure 3 for an example). This was a part of tests in Iceland under SAND-E (Semi-Autonomous Navigation for Detrital Environments), a NASA PSTAR funded project led by Dr. Ryan Ewing at Texas A&M University.Figure 3: Classifier output overlaid on one camera image during a SAND-E traverse in Iceland field tests.While ASAS-CRATERS is a multi-mission payload, near-term demonstrations are targeted for upcoming lunar missions in 2022 and 2023.AcknowledgementsThe authors would like to thank the Canadian Space Agency (CSA) for funding the development of ASAS-CRATERS and previous technology developments.References[1] Francis R. et al. (2014) SpaceOps. DOI: 10.2514/6.2014-1798. [2] Gaines D. et al. (2016) PlanRob, 115-125. [3] Faragalli M. et al. (2018) i-SAIRAS.

Pitted impact deposits on Vesta show higher reflectance and pyroxene absorption band strengths compared to their immediate surroundings and other typical Vestan materials. We investigated whether heating to different temperatures for different durations of Vestan regolith analog materials can reproduce these spectral characteristics using mixtures of HEDs, the carbonaceous chondrite Murchison, and terrestrial analogs. We find no consistent spectral trend due merely to temperature increases, but observed that the interiors of many heated samples show both higher reflectance and pyroxene band I strength than their heated surfaces. With electron probe microanalysis, we additionally observe the formation of hematite, which could account for the higher reflectance. The presence of hematite indicates oxidation occurring in the sample interiors. In combination with heat, this might cause the increase of pyroxene band strengths through migration of iron cations. The effect grows larger with increasing temperature and duration, although temperature appears to play the more dominant role. A higher proportion of Murchison or the terrestrial carbonaceous chondrite analog within our mixtures also appears to facilitate the onset of oxidation. Our observations suggest that both the introduction of exogenic material on Vesta as well as the heating from impacts were necessary to enable the process (possibly oxidation) causing the observed spectral changes.

Ceres is a partially differentiated dwarf planet located in the main asteroid belt. Consus crater (diameter similar to 64 km) is one of the oldest impact features (similar to 450 Ma) on the Cerean surface that surprisingly still shows a large variety of color lithologies, including exposures of bright material, which are thought to be brine residues. Here, we present new results that help in understanding the structure and composition of the Cerean crust. These results were deduced by using newly processed Dawn Framing Camera (FC) color imagery and FC clear filter images combined with infrared spectral data of Dawn's Visible and Infrared Spectrometer (VIR). Consus exhibits a variety of color lithologies, which we describe in detail. Interestingly, we found three spectrally different types of bright material exposed by a large old crater on Consus' floor. One of these, the yellowish bright material (Nathues et al., 2023, ) and its modification, shows spectral signatures consistent with ammonium-enriched smectites. We hypothesize that the ammonium in these smectites stems from contact with ascending brines, originating from a low-lying former brine ocean that has been enriched in ammonium during the differentiation and freezing process of the Cerean crust. This enrichment is mainly due to ammonium uptake by sheet silicates. If such an ammonium enrichment occurred over long-time scales on a global scale, this process may explain the vast presence of ammonium on the Cerean surface. Therefore, an outer solar system origin of Ceres is possibly not needed to explain the global presence of ammonium. Ceres is the largest object in the asteroid belt and surprisingly exhibits surface features formed by recent cryo-volcanism, although evolution models predicted an inactive, completely frozen body. Cryo-volcanism possibly stems from a brine layer at the crust-mantle transition. The global presence of ammonium on the Cerean surface led to the conclusion of a potential outer solar system origin of Ceres. Here, we investigate the structure of its crust, by studying one of the older, but still mineralogical diverse, impact craters that excavated originally low-lying materials. For our study, we are using data of the Dawn Framing Camera, spectral data of the Visible and Infrared Spectrometer as well as several geoscientific remote sensing methods. We describe "yellowish bright material" for the first time (Nathues et al., 2023, ), that is spectrally unique in our color data and exhibits a strong absorption feature in the near-infrared caused by ammonium. We hypothesize that the ammonium enrichment of this surface material is mainly a consequence of an ammonium exchange between rising brines and near-surface phyllosilicates. If true, this would strengthen the case for the existence of a low-lying ammonium-rich brine layer, which in turn could weaken the hypothesis of an outer solar system origin for Ceres. The old impact crater Consus still shows a large variety of color lithologies The yellow bright material lithology is ammonium-enriched We hypothesize that this ammonium stems from ascending originally low-lying brines

Laboratory measurements of reflectance spectra of rocks and minerals at multiple viewing geometries are important for interpreting spacecraft data of planetary surfaces. However, efficiently acquiring such measurements is challenging, as it requires a custom goniometer that can accommodate multiple, bulky samples beneath a movable light source and detector. Most spectrogoniometric laboratory work to date has focused on mineral mixtures and particulates, yet it is also critical to characterize natural rock surfaces to understand the influence of texture and alteration. We designed the Three-Axis N-sample Automated Goniometer for Evaluating Reflectance (TANAGER) specifically to rapidly acquire spectra of natural rock surfaces across the full scattering hemisphere. TANAGER has its light source and the spectrometer's fiber optic mounted on rotating and tilting arcs, with a rotating azimuth stage and six-position sample tray, all of which are fully motorized and integrated with a Malvern PanAnalytical ASD FieldSpec4 Hi-Res reflectance spectrometer. Using well-characterized color calibration targets, we have validated the accuracy and repeatability of TANAGER spectra. We also confirm that the system introduces no discernible noise or artifacts. All design schematics and control software for TANAGER are open-source and available for use and modification by the larger scientific community.