The ROMA database (ROck reflectance for MArtian in situ exploration, https://roma.univ-lyon1.fr) provides the reflectance spectra between 0.4 and 3–4 μm of various terrestrial, Martian, and synthetic ...samples, as a means to document reference measurements for comparison with data acquired by visible and near‐infrared spectrometers on planetary surfaces, with a focus on current and future Martian observations by the Perseverance (Mars 2020 mission) and Rosalind Franklin (ExoMars) rovers. The main specificity of this database is to include a significant fraction of spectra of unprocessed rock, which are more realistic analogs and often have different spectral features than the fine powders more commonly analyzed in reflectance spectroscopy. Additionally, these measurements were acquired with a spectrometer whose spot size is similar to those of the SuperCam instrument (Mars 2020 mission) at a few meters from a target. Supplementary information are provided in the ROMA database: higher‐level data (such as absorption band parameters) as well as sample mineralogy estimated by whole‐rock X‐ray diffraction analyses. Future comparisons with this database will help improve the interpretation of spectral measurements acquired on the Martian surface. This work introduces the aim of the library and its current state, but additional data on intact natural rock surfaces will likely be added in the future.
Key Points
We present a database of rock reflectance spectra measured between 0.4 and 3–4 μm
Similarities in measurement spot size, mineralogy, and rock texture will allow comparisons with analyzes performed on the Martian surface
This database is made available to the community for future spectral comparisons
Moon Mineralogy Mapper (M3) spectroscopic data and high‐resolution imagery data sets were used to study the mineralogy and geology of the 207 km diameter Humboldt crater. Analyses of M3 data, using a ...custom‐made method for M3 spectra continuum removal and spectral parameters calculation, reveal multiple pure crystalline plagioclase detections within the Humboldt crater central peak complex, hinting at its crustal origin. However, olivine, spinel, and glass are observed in the crater walls and rims, suggesting these minerals derive from shallower levels than the plagioclase of the central peak complex. High‐calcium pyroxenes are detected in association with volcanic deposits emplaced on the crater's floor. Geologic mapping was performed, and the age of Humboldt crater's units was estimated from crater counts. Results suggest that volcanic activity within this floor‐fractured crater spanned over a billion years. The felsic mineralogy of the central peak complex region, which presumably excavated deeper material, and the shallow mafic minerals (olivine and spinel) detected in Humboldt crater walls and rim are not in accordance with the general view of the structure of the lunar crust. Our observations can be explained by the presence of a mafic pluton emplaced in the anorthositic crust prior to the Humboldt‐forming impact event. Alternatively, the excavation of Australe basin ejecta could explain the observed mineralogical detections. This highlights the importance of detailed combined mineralogical and geological remote sensing studies to assess the heterogeneity of the lunar crust.
Plain Language Summary
Humboldt crater is a 207 km diameter complex impact crater located on the farside of the Moon. A central peak sits in its center, whereas its periphery is occupied by volcanic deposits. The peak was formed during the crater‐forming impact event, as material from depth was brought up to the surface. In this study, we make use of the light that is reflected from the lunar surface to infer its composition. We used data from the Moon Mineralogy Mapper (M3) instrument, a visible near‐infrared spectrometer, that orbited the Moon between 2008 and 2009. We surveyed the mineralogy of the different crater units and dated them by crater counts. We found that volcanic activity in Humboldt crater might have spanned over 1 Ga. Plagioclase minerals detected in the Humboldt crater central peak hints at its crustal origin, whereas the mineralogic assemblage of the crater walls and rim is more puzzling and raises questions about the lunar crust structure.
Key Points
Multiple pure crystalline plagioclase are detected in the Humboldt crater central peak complex, hinting at its crustal origin
Olivine, spinel, and glass are detected in the crater's walls and rim, suggesting their shallow origin, possibly linked to a plutonic event
Crater counts performed on the crater volcanic deposits suggest that volcanic activity in Humboldt crater spanned over a billion years
The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here, we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the ...mission on the crater floor, using the visible and near‐infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine‐bearing rocks at the bottom of the stratigraphy and high‐Ca pyroxene‐bearing rocks at the top. This is distinct from the overall low‐Ca pyroxene‐bearing composition of the watershed of Jezero and points toward an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.
Plain Language Summary
We present the results of the analysis of rocks and regolith measured during the first year after landing of the Perseverance rover on Mars. The analytical technique used is reflectance spectroscopy (the measurement of the light reflected by surfaces), which primarily provides information on mineralogy. The mineralogical composition of the magmatic rocks located near the landing site indicates that they have experienced several distinct episodes of interaction with water in the past, of relatively low intensity. Soil analysis reveals a composition similar to what has been observed at other sites on Mars, with a contribution from the disintegration of local rocks. The samples that are collected by Perseverance at the crater floor and brought back to Earth are representative of the diversity of the different geological units explored by the rover.
Key Points
Mineralogy of rocks, regolith, and dust of the crater floor of Jezero, Mars was inferred from SuperCam reflectance data
Assemblages suggest limited aqueous alteration of igneous rocks, followed by evaporation‐induced deposition of sulfates
Samples collected on the crater floor for return to Earth are representative of the geological diversity and witness past‐aqueous processes
•Detections of smectites, chlorites, carbonates and possible serpentine.•Alteration evidence of the first 7km of the crust between the Hellas and Isidis basins.•Evidence of carbonation of the martian ...crust.
Recent investigations of alteration of martian crustal outcrops suggest putative crustal hydrothermal systems, which are favorable environments for the emergence of life. In this study, we perform an analysis of the CRISM targeted observations covering crustal outcrops in the region between the Hellas and Isidis basins with the goal of investigating the alteration phases. Over the wide studied region, we detect the presence of possible serpentines, chlorites, smectites and carbonates. These detections occur within ejecta blankets, crater walls and central uplifts of impact craters. We investigate the relation between the observed associations of minerals and the ages of the impact craters assessed by crater count. No clear relation is observed. We also investigate the relationship between the group of detected mineral and the pre-impact depth of the studied outcrops assessed from the size of the impact craters. This method allows us to reconstruct the pre-impact cross-section. We suggest that alteration of the first 7km of the crust between the Hellas and Isidis basins may have undergone alteration processes.
Moon Mineralogy Mapper spectroscopic data were used to investigate the mineralogy of a selection of impact craters' central peaks or peak rings, in order to characterize the lunar crust‐mantle ...interface, and assess its lateral and vertical heterogeneity. The depth of origin of the craters' central peaks or peak rings was calculated using empirical equations, and compared to Gravity Recovery and Interior Laboratory crustal thickness models to select craters tapping within +10/−20 km of the crust‐mantle interface. Our results show that plagioclase is widely detected, including in craters allegedly sampling lower crustal to mantle material, except in central peaks where Low‐Calcium Pyroxene was detected. Olivine detections are scarce, and identified in material assumed to be derived from both above and below the crust‐mantle interface. Mineralogical detections in central peaks show that there is an evolution of the pyroxene composition with depth, that may correspond to the transition from the crust to the mantle. The correlation between High‐Calcium Pyroxene and some pyroxene‐dominated mixture spectra with the location of maria and cryptomaria hints at the existence of lateral heterogeneities as deep as the crust‐mantle interface.
Plain Language Summary
This study surveys the mineralogy of 36 lunar impact craters scattered across the lunar surface. All these craters present a central peak or peak ring, inherited from the impact, where material from depth was brought up to the surface. According to our calculations, these craters should sample material originating from as deep as the interface between the crust and the mantle (+10/−20 km). We make use of visible near‐infrared spectroscopy (we investigate the light that is reflected from the lunar surface) in order to infer the central peaks compositions. We detected several minerals within the craters, including plagioclase, olivine, spinel, and pyroxene. An evolution of the composition of pyroxene (from High‐Calcium to Low‐Calcium) is observed with depth. We also demonstrate the presence of lateral heterogeneities within the crust and at the crust/mantle interface.
Key Points
Plagioclase is widely detected in the central peaks of craters allegedly sampling the lower crust or mantle, except where LCP is observed
Lateral heterogeneities at the crust‐mantle interface and a pyroxene compositional evolution with depth (from HCP to LCP) were observed
This study's mineralogical observations support the GRAIL crustal thickness model 1 better than the model 3
Perseverance explored two geological units on the floor of Jezero Crater over the first 420 Martian days of the Mars2020 mission. These units, the Máaz and Séítah formations, are interpreted to be ...igneous in origin, with traces of alteration. We report the detection of carbonate phases along the rover traverse based on laser‐induced breakdown spectroscopy (LIBS), infrared reflectance spectroscopy (IRS), and time‐resolved Raman (TRR) spectroscopy by the SuperCam instrument. Carbonates are identified through direct detection of vibrational modes of CO3 functional groups (IRS and TRR), major oxides content, and ratios of C and O signal intensities (LIBS). In Séítah, the carbonates are consistent with magnesite‐siderite solid solutions (Mg# of 0.42–0.70) with low calcium contents (<5 wt.% CaO). They are detected together with olivine in IRS and TRR spectra. LIBS and IRS also indicate a spatial association of the carbonates with clays. Carbonates in Máaz are detected in fewer points, as: (a) siderite (Mg# as low as 0.03); (b) carbonate‐containing coatings, enriched in Mg (Mg# ∼0.82) and spatially associated with different salts. Overall, using conservative criteria, carbonate detections are rare in LIBS (∼30/2,000 points), IRS (∼15/2,000 points), and TRR (1/150 points) data. This is best explained by (a) a low carbonate content overall, (b) small carbonate grains mixed with other phases, (c) intrinsic complexity of in situ measurements. This is consistent with orbital observations of Jezero crater, and similar to compositions of carbonates previously reported in Martian meteorites. This suggests a limited carbonation of Jezero rocks by locally equilibrated fluids.
Plain Language Summary
Carbonates are mineral phases that generally form by alteration of primary, magmatic minerals. This alteration process may occur under a variety of environmental conditions, which affect the resulting carbonate phase: its abundance, composition, spatial distribution and the mineral phases it is associated with. Consequently, carbonates keep track of the environmental conditions under which they formed, and in particular, the amount of CO2 and liquid water involved in their formation. Understanding the history of both water and CO2 on Mars is critical to better understand the evolution of the red planet and its atmosphere, but also the origin of the water on Earth, and possibly the origin of life. Since the beginning of the Mars2020 mission in Jezero Crater, the SuperCam instrument has analyzed more than 200 rocks of the crater floor, and detected carbonates along Perseverance's traverse. Carbonates are found in low amounts, and are therefore complex to identify; we use SuperCam's combination of investigation techniques and a specifically developed methodology to strengthen the identification of carbonate phases and their characterization. Even though Jezero crater hosted a lake billions of years ago, the detected carbonates appear to have formed in smaller amounts of water, after the lake had disappeared.
Key Points
Carbonates are detected along Perseverance's traverse in Jezero Crater with SuperCam using laser‐induced breakdown spectroscopy, IR and Raman spectroscopy
Carbonate abundance is low overall, consistent with the weak carbonate signatures observed from orbit in the explored units
The detected carbonates have variable compositions within the magnesite‐siderite series, and likely reflect multiple alteration episodes
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.
Plain Language Summary
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.
Key Points
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
MarsSI (Acronym for Mars System of Information, https://emars.univ-lyon1.fr/MarsSI/) is a web Geographic Information System application which helps managing and processing martian orbital data. The ...MarsSI facility is part of the web portal called PSUP (Planetary SUrface Portal) developed by the Observatories of Paris Sud (OSUPS) and Lyon (OSUL) to provide users with efficient and easy access to data products dedicated to the martian surface. The portal proposes 1) the management and processing of data thanks to MarsSI and 2) the visualization and merging of high level (imagery, spectral, and topographic) products and catalogs via a web-based user interface (MarsVisu). The portal PSUP as well as the facility MarsVisu is detailed in a companion paper (Poulet et al., 2018). The purpose of this paper is to describe the facility MarsSI. From this application, users are able to easily and rapidly select observations, process raw data via automatic pipelines, and get back final products which can be visualized under Geographic Information Systems. Moreover, MarsSI also contains an automatic stereo-restitution pipeline in order to produce Digital Terrain Models (DTM) on demand from HiRISE (High Resolution Imaging Science Experiment) or CTX (Context Camera) pair-images. This application is funded by the European Union's Seventh Framework Programme (FP7/2007–2013) (ERC project eMars, No. 280168) and has been developed in the scope of Mars, but the design is applicable to any other planetary body of the solar system.
•MarsSI is a web application managing and processing Martian orbital data on demand.•MarsSI proposes on demand automatic stereo-restitution from HiRISE or CTX pair-images.•While developed in the scope of Mars, the design is applicable to any other planetary body of the solar system.
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.
Séítah is the stratigraphically lowest formation visited by Perseverance in the Jezero crater floor. We present the data obtained by SuperCam: texture by imagery, chemistry by Laser-Induced Breakdown ...Spectroscopy, and mineralogy by Supercam Visible and Infrared reflectance and Raman spectroscopy. The Séítah formation consists of igneous, weakly altered rocks dominated by millimeter-sized grains of olivine with the presence of low-Ca and high-Ca pyroxenes, and other primary minerals (e.g., plagioclase, Cr-Fe-Ti oxides, phosphates). Along a ∼140 m long section in Séítah, SuperCam analyses showed evidence of geochemical and mineralogical variations, from the contact with the overlying Máaz formation, going deeper in the formation. Bulk rock and olivine Mg#, grain size, olivine content increase gradually further from the contact. Along the section, olivine Mg# is not in equilibrium with the bulk rock Mg#, indicating local olivine accumulation. These observations are consistent with Séítah being the deep ultramafic member of a cumulate series derived from the fractional crystallization and slow cooling of the parent magma at depth. Possible magmatic processes and exhumation mechanisms of Séítah are discussed. Séítah rocks show some affinity with some rocks at Gusev crater, and with some Martian meteorites suggesting that such rocks are not rare on the surface of Mars. Séítah is part of the Nili Fossae regional olivine-carbonate unit observed from orbit. Future exploration of Perseverance on the rim and outside of the crater will help determine if the observations from the crater floor can be extrapolated to the whole unit or if this unit is composed of distinct sub-units with various origins.
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