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From Pioneer 10 to Juno, which is still active, several missions and space observatories have studied Jupiter’s atmosphere. Complementary, although limited by the telluric bands of water vapor, ground-based observations continue providing information about its vertical structure and its distribution around the planet. The main chemical composition of Jupiter’s atmosphere has been unraveled but lots of questions still remain open, such as the global abundance of water, the responsible chemistry for the coloration of the clouds, or what drives the aurora [1-2]. Moreover, observations by NIMS/Galileo [3-4] and VIMS/Cassini [5], have demonstrated the remarkable potential of VIS-NIR spectrometry for characterizing the composition and dynamics of planetary atmospheres [6]. The Moons And Jupiter Imaging Spectrometer (MAJIS) instrument is part of the science payload of the ESA L-Class mission JUICE (Jupiter ICy Moons Explorer) [7] to be launched in 2022 with an arrival at Jupiter in 2031. MAJIS combines two spectral channels able to cover the 0.5 – 2.35 μm range (VIS-NIR channel) and the 2.25 – 5.54 μm range (IR channel) [8]. As part of its scientific objectives, MAJIS will investigate the composition, structure, dynamics and evolution of Jupiter’s atmosphere at different levels, trace tropospheric cloud features, and characterize major and minor species, aerosols properties, and hot spots [9]. As explained by Langevin et al. [9], the spectral resolving power of MAJIS exceeds by three times that of NIMS or VIMS, with a spatial resolution four times better than NIMS, so it will efficiently track tropospheric processes such as clouds and hazes. Moreover, the close to equatorial orbit of JUICE for most of the mission will provide a comprehensive coverage of Jupiter in local time complementary to JIRAM/Juno [9]. We are interested in the scientific analysis of the MAJIS observations regarding the composition of Jupiter’s atmosphere, specifically on the H2O and CH4 contents, which are the most abundant species in the troposphere as a whole, after H2 and He [1]. Although it is expected that water vapor has a higher global volume mixing ratio than CH4 in the deep troposphere, this has yet to be observed [1]. Additionally, the strong spectral features due to crystalline water ice (1.5 µm and 2.0 µm) require a large abundance of water to be explained [10]. Therefore, we would like to perform simulations of different test cases with respect to the viewing geometries of MAJIS and the technical properties of its Flight Model VIS-NIR detector [11]. To proceed, we need to adapt the Radiative Transfer code developed at the Belgian Institute for Space Aeronomy (BIRA-IASB), ASIMUT-ALVL. It has been extensively used to characterize Mars and Venus atmospheres [12-19]. This tool is able to perform forward model simulations and atmospheric spectrum retrievals in nadir and limb geometries. To apply it to Jupiter’s atmosphere, some changes need to be done, such as implementing Jupiter’s physical parameters and adding the Rayleigh scattering contribution due to the dominant atmospheric species H2 and He. A more demanding modification to the code concerns the treatment of the Collision-Induced Absorption (CIA) due to H2-H2 and H2-He molecular systems. A typical atmosphere’s vertical structure of Jupiter has been retrieved from [20-21]. The molecular line-lists and cross-sections have been implemented from the HITRAN online database with line parameters adequate for an H2-dominant atmosphere. Additionally, the microphysical parameters of the clouds and aerosols have been obtained from [22]. The different contributions to the spectra are being identified then simulated and finally validated through comparison with previous works [20-21]. This methodology ensures that each radiative contribution is well-understood and correctly implemented into ASIMUT-ALVL before assessing the performances of the MAJIS VIS-NIR channel to characterize the vertical structure of the Jovian atmosphere. In this presentation, we will describe the different contributions and the challenges we faced for their implementation. A preliminary sensitivity analysis of MAJIS VIS-NIR will be discussed. Acknowledgments This project acknowledges the support of M. López-Puertas and the funding provided by the Scientific Research Fund (FNRS) through the Aspirant Grant: 34828772 MAJIS detectors and impact on science. References [1] Mc Grath, M.A., et al., Ed. 2004, Cambridge University Press, p. 59-77. [2] MAJIS Team, JUICE Definition Study Report, 2014. [3] Irwin, P.G.J., et al. Icarus, 2001. 149(2): p. 397-415. [4] Baines, K.H., et al. Icarus, 2002. 159(1): p. 74-94. [5] Brown, R.H., et al. Icarus, 2003. 164(2): p. 461-470. [6] Langevin, Y., et al., Lunar and Planetary Science Conference, 2014. [7] Grasset, O., et al., Planetary and Space Science, Vol. 78, pp. 1-21, 2013. [8] Guerri, I., et al., International Society for Optics and Photonics, Vol. 10690, 2018. [9] Langevin, Y., et al., EPSC, 2013. P. EPSC2013-548-1. [10] Grassi, D., et al., Journal of Geophysical Research: Planets, 2020. 125.4: e2019JE006206. [11] Cisneros-González, M. E. et al., Space Telescopes and Instrumentation in Proc. SPIE 2020, 11443, 114431L. [12] Montmessin, F., et al. Icarus, 2017. 297: p. 195-216. [13] Vandaele, A.C., et al. Optics Express, 2013. 21(18): p. 21148. [14] Vandaele , A.C., et al. Adv. Space Res., 2016. 57: p. 443-458. [15] Vandaele , A.C., et al. Icarus, 2016. 272: p. 48-59. [16] Vandaele, A.C., et al. Icarus, 2017. 295: p. 1-15. [17] Vandaele, A.C., et al. Planet. Space Sci., 2015. 119: p. 233-249. [18] Neefs, E., et al., Applied Optics, 2015. 54(28): p. 8494-8520. [19] Robert, S., et al., Planet. Space Sci., 2016. 124: p. 94-104. [20] López-Puertas, M., et al., The Astronomical Journal, 2018. 156.4: 169. [21] Guerlet, S., et al. Icarus, 2020. 351: 113935. [22] Montañés-Rodríguez, P., et al., The Astrophysical Journal Letters, 2015, vol. 801, no 1, p. L8.

In 2022 rover, ESA-Roscosmos will launch rover to land at Oxia Planum on Mars. Oxia Planum is a wide, Noachian-age, phyllosilicate-bearing plain located between Mawrth and Ares Valles. The bedrock phyllosilicate deposits at Oxia Planum is Fe,Mg-rich and one of the largest exposures of this type on Mars, with a thickness of more than 10 m [1]. When characterized in the near infrared by CRISM and OMEGA instruments, the bedrock deposits exhibit absorptions that suggest the presence of Fe,Mg-rich phyllosilicates with significant amounts of Fe2+ in octahedral sites (i.e., trioctahedral) [2]. The typical spectrum is best matched by saponite or vermiculite, but an accurate spectral match is lacking so far. Because precise mineral composition of the bedrock is not fully understood, limited conclusions can be drawn regarding the aqueous evolution and habitability potential of Oxia – the main scientific aim of the ExoMars 2022 mission. To fill this gap, and to better prepare for in-situ analyses by the ExoMars2022 rover, we performed a survey of potential terrestrial analogue rocks. We have identified terrestrial deposits of Fe-rich, trioctahedral vermiculite and perform spectral comparisons with the Martian substrate. Analogues from two terrestrial sites were obtained: (1) vermiculitized chlorite-schists from Blue Spur, Otago, New Zealand and [3] (2) basaltic tuffs and pyroclastics from Granby, Massachusetts, USA, with Fe-rich clays filling amygdales [4]. The samples were characterized by X-ray diffraction to understand chemistry and structure of clay minerals and by NIR spectroscopy in order to provide further structural details and to assess the match to Oxia Planum bedrock clays. XRD was performed on bulk rock samples as well as for separated clay fraction minerals. Near Infrared (NIR) spectra for each sample were collected using a reflectance spectrometer in the near-infrared (0.8–4.2 μm) mode. Analysis was performed on powdered samples, under ambient temperature and pressure conditions. Both analogues have been added to a newly built Planetary Terrestrial Analogue Library (PTAL) rock collection and spectral library. Deposits in Blue Spur formed by erosion and deposition of greenschist-facies quartzo-feldspathic schists rich in Fe-rich chlorite. Due to rapid erosion and non-oxidizing or mild oxidative conditions [3] chlorite remained unoxidized when buried. Later interactions with groundwater caused formation of trioctahedral vermiculite and progressive alteration of deposit led to illitization and kaolinitization For our purposes we have collected samples of pristine schist clasts, greenish (unoxidized) vermiculitized material and pale, illitized clasts [3]. The XRD patterns of oriented clay fraction separates suggest the presence of chlorite in pristine material, trioctahedral vermiculite in greenish samples that underwent alteration in anoxic conditions, and interstratified illite-vermiculite in more oxidized samples.NIR spectroscopy analysis of Otago samples tends to indicate that the nature and overall Fe content is broadly similar to the phyllosilicates at Oxia. Furthermore, illitization of the vermiculite seen spectrally in Otago is likely limited for Oxia. This means that vermiculite at Oxia is a rather pure, one-phase mineral that underwent only minor (if any) post-depositional alterations toward illite. The Granby Tuff consists of basaltic flows and volcanic ash units. In places, it contains zones of vesicular basalts that have amygdales filled with calcite and dark-brown clays. The clays filling the amygdales are of apparent hydrothermal origin, that is precipitated in gas vesicles from solutions generated by hydrothermal alteration of the basaltic tuff. The clays were reported to be either saponite or vermiculite [4]. The XRD patterns of the oriented clay fraction separates from these tuffs reveal the presence of well-crystallized, trioctahedral vermiculite and various amounts of saponite in different samples. In NIR spectroscopy, Granby samples show quite a good spectral match to Oxia and indicate that saponite, present in Granby, is absent from Oxia spectra. Oxia deposits are likely pure vermiculite rather than a mixture of saponite and vermiculite. Additionally, other spectral features suggest that the Granby clays have different Fe/Mg ratios than minerals of Oxia Planum, or a different (plausibly lower) oxidation state of Fe in the clay structure. Our spectral analogue study shows that rocks containing Fe2+-rich vermiculite, locally with octahedral Al and (oxidized) Fe3+, are likely the main component of bedrock phyllosilicates at Oxia Planum. In terms of clay structure and its di- versus trioctahedral nature, Oxia deposits are matched best by a vermiculite-saponite from hydrothermally-derived settings (Granby Tuffs), although the contribution of saponite must be minor at Oxia. Comparison of Otago vermiculite to Oxia shows high Fe content in Oxia and a similar oxidation state. Spectral inconsistencies between Otago and Oxia related to presence of Al in the clay structure allow us to conclude that Oxia bedrock deposits were likely not oxidized nor illitized after formation. Acknowledgments: This project has received funding from the EU Horizon 2020 Research and Innovation Program (687302, PTAL), and the Research Council of Norway (Centres of Excellence funding 223272). References: [1] Quantin-Nataf C. et al. 2020: Astrobiology, accepted. [2] Carter J. et al. 2016. 47th Lunar and Planetary Science Conference. Abstract no. 2064. [3] Craw D. 1984. Clay Minerals 19: 509-520. [4] April R.H. and Keller D.M. 1992. Clays and Clay Minerals 40: 22-31.

The PTAL Project: Mars2020/Perseverance 1 and ExoMars/Rosalind Franklin 2 rovers will look for traces of present or past life on Mars. To do so, the spectroscopic systems included in their analytical payloads will investigate the geochemistry and mineralogy of Martian rocks and soils to detect geological samples that could potentially host biomarkers. In order to optimize the scientific exploitation of planetary spectroscopic analysis, the PTAL project will provide the scientific community with a novel library of terrestrial analogue materials that have been selected based on their similarity to well-known Martian geological contexts. Funded by the European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 687302, the PTAL online platform will be released to public in October 2021. As further detailed by Werner et al. during this conference, the core of the database are the spectroscopic data collected by means of multiple Raman (University of Valladolid, UVa, Spain), NIR (University of Paris-Sud, UP-Sud, France) and LIBS (French National Centre for Scientific Research, IRAP, France) systems. Spectroscopic results are additionally supported by X-ray diffractograms and thin section observations (University of Oslo, Uio, Norway) to provide an exhaustive geochemical and mineralogical characterization of the samples. The whole set of data, collected by means of both commercial systems and prototypes/flight spares (FS) of analytical instruments validated for Mars exploration (RLS-Sim, MicrOmega-FS, ChemCam-FS), will be available to the public thanks to a dedicated online platform, which main characteristics are detailed below.The online PTAL platform:The PTAL database will be accessible to public through the following URL: http://erica.uva.es/PTAL/. After login (credentials will be provided by the PTAL consortium upon request), future users will have access to the whole set of diffractometric and spectroscopic data collected from a total of 102 analogue materials. On one side, clicking on the sample name, the metadata associated to the selected terrestrial analogues are provided (e.g., Sample Name and Lithology, Sampling Campaign and coordinates) together with high quality pictures of the terrestrial analogue sample. On the other side, by clicking on “analytical summary”, the PTAL platform displays the list of NIR, LIBS, Raman and XRD analyses associated to the selected terrestrial analogue, together with a table summarizing and comparing the main results gathered from each technique (Figure 1).Figure 1: Screenshots collected from the PTAL online database: a) list of samples, b) summary result of a selected analogue, and c) online visualization of a selected Raman spectrum.At this stage, all NIR, XRD, Raman and LIBS data have been successfully uploaded to the PTAL database 3–5. In detail, the PTAL database provides access to 102 diffractograms (1 per sample), 102 LIBS spectra, 102 NIR spectra collected by means of the commercial spectrometer, and 102 NIR data cubes obtained through the MicrOmega system (of them composed of 62500 spectra collected at steps of 20µm in a field of view of 5x5mm). Regarding Raman results, only the spectra providing the highest mineralogical information were uploaded to the PTAL database. As such, the number of Raman spectra was reduced from over 4500 to 577 (an average of 5-6 spectra per sample). 245 of them were collected by means of the RLS-Sim, while the remaining 332 were obtained with a commercial spectrometer. All data can be either visualized online or downloaded for further data comparison and processing. In this framework, it must be underlined the PTAL platform also gives access to a dedicated software for data treatment. Named SpectPro, the details of this downloadable software are detailed below.The SpectPro software:Developed in the framework of the ExoMars mission 6, the PTAL version of the SpectPro software could be downloaded from the PTAL webpage (download section) for both windows and MacOs operating systems. Through the SpectPro software, PTAL users will be able to run individual and multi-spectra operations such as labelling, trimming, shifting, normalization, baseline correction (see Figure 2).Figure 2: Screenshot of PTAL/SpectPro, in which the main functionalities and characteristics of the software are highlighted.Among the main functionalities, the software also features a general-purpose spectrum calculator to perform lineal combinations, product and derivative of spectra, among others. The software team has been working to facilitate a direct access from SpectPro to the PTAL database, using the same credentials for access to the PTAL web interface. This connection will boost the capability of the scientist working in a planetary mission (but not only) to perform a fast and comprehensive characterization and identification of the mineral phases present in a sample by comparing the data obtained from the sample with the extensive spectral information included in the PTAL database. This will be possible by profiting from the navigation pane included in SpectPro. In addition, using the peak detection capabilities of SpectPro, it will be possible to perform sample identification based on the acquired spectra.Acknowledgments: This work is financed through the European Research Council in the H2020- COMPET-2015 programme (grant 687302).References: 1 Farley, K. A. et al. Space Sci. Rev. 216, 142 (2020); 2 Vago, J. L. et al. Astrobiology 17, 471–510 (2017); 3 Lantz, C. et al. Planet. Space Sci. 189, 104989 (2020); 4 Loizeau, D. et al. Planet. Space Sci. 193, 105087 (2020); 5 Veneranda, M. et al. J. Raman Spectrosc. 1–19 (2019) doi:10.1002/jrs.5652; 6 Lopez-Reyes G. et al. European Planetary Science Congress 2018 vol. 12 1–2 (2018).

Serpentinization and carbonation have affected ultramafic rocks on Noachian Mars in several places called here serpentinization-carbonation systems (SCS). Among the most prominent SCS revealing mineral assemblages characteristic of serpentinization/carbonation is the Nili Fossae region [1]. Jezero crater – the target of the Mars 2020 rover –hosted a paleolake which constitutes a sink for sediments from Nili Fossae [1]. Thanks to the near infrared spectrometer onboard Mars2020 [2], the mission has the potential to offer ground truth measurement for other putative serpentinization/carbonation system documented on Mars. Several important aspects that may be addressed are: Do carbonates result from primary alteration of olivine-rich lithologies or are they derived by reprocessing of previous alteration minerals [3]? What is the composition? and nature of the protolith, which appear to be constituted of considerable amounts of olivine [4]? To reveal critical information regarding the conditions of serpentinization/carbonation, accessory minerals need detailed studies [1; 5]. In case of Jezero Crater, and serpentinization on Mars in general, the main alteration minerals are identified, but little is known about the accessory minerals. The Nili Fossae-Jezero system has potential analogues in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Norway (PTAL collection, https://www.ptal.eu). Here, distinct mineral assemblages record different stages of hydration and carbonation of ultramafic rocks [6]. We perform petrological and mineralogical analyses on thin sections to characterize the major and trace minerals and combine with Near Infrared (NIR) spectroscopy measurements. A set of spectral parameters are defined and compare to spectral parameters previously used on CRISM and OMEGA data [1, 4, 7, 8]. We study the significance of the mineralogical assemblages including nature of accessory minerals. Effect of the presence of accessory minerals on the NIR signal is investigated and their potential incidence on the amount of H2/CH4 production in mafic or ultramafic system is discussed [5]. We started to apply the newly defined spectral parameters on several SCS on Mars. Results confirm local carbonation of earlier serpentinized rocks and suggest that different protoliths could have led to diversity of mineralogical associations in SCS on Mars. Multiple detection of brucite are also suggested for the first time on Mars. Altogether our results help to better describe key geochemical conditions of the SCS on Mars for habitability potential of the martian crust and Mars’s evolution. References: Brown, A. J., et al. EPSL1-2 (2010): 174-182. Wiens, R.C., et al. Space Sci Rev217, 4 (2021). Horgan, B., et al. Second International Mars Sample Return. Vol. 2071. 2018. Ody, A., et al. JGR: Planets2 (2013): 234-262. Klein, F., et al. Lithos178 (2013): 55-69. Bjerga, A., et al. Lithos227 (2015): 21-36. Viviano-Beck et al, JGR: Planets 118.9 (2013) Viviano-Beck et al, JGR: Planets 119.6 (2014)

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

The SuperCam Instrument Suite [1-4], a US-French-Spanish-Danish collaboration, consists of three separate units: the Body Unit (BU) within the Rover [2], the Mast Unit (MU) at the top of the Perseverance Remote Sensing Mast [3], and Calibration Targets [4] located on the rover deck. SuperCam includes a passive visible/near-infrared (VISIR) spectroscopy system that will identify minerals near the rover (mm-scale) to distant outcrops (m-scale) over an extended wavelength range (0.385-0.465 µm, 0.536-0.853 µm, 1.3-2.6 µm) that is diagnostic for most mineral classes.The infrared spectrometer (IRS) in the MU [5] uses an acousto-optic tunable filter (AOTF) excited by a RF signal to successively diffract up to 256 different wavelengths ranging between 1.3 and 2.6 µm on one of two available photodiodes to produce a single spectrum in about 80 seconds at a spectral resolution of 5-20 nm. The field-of-view (FOV) of the IRS is 1.15 mrad and is co-aligned with the RMI boresight. The visible (VIS) system in the BU comprises three spectrometers covering the UV (245 – 340 nm), violet (385 – 465 nm), and visible and near-infrared (VNIR, 536–853 nm). The spectrometers are fed by light collected by the telescope in the MU through an optical fiber connecting the MU and BU. The violet spectrometer has a spectral resolution of 0.12 nm, and the VNIR transmission spectrometer has a spectral resolution of 0.35 – 0.70 nm. The VIS FOV is 0.74 mrad and co-aligned with the IR FOV.Several SuperCam calibration targets (SCCT) are dedicated to VISIR spectroscopy, including an AluWhite white target, an Aeroglaze Z307 black target, and red, cyan, and green color targets [4]. Several of the other targets whose primary purpose is for other techniques exhibit useful VISIR spectral features and will be observed [5].Raw data will be converted to radiance (W/m2/sr/µm) with calibrated wavelengths using the instrument transfer function [6-7]. Relative reflectance spectra will be generated by dividing the calibrated radiance spectrum by either (1) a Mars atmospheric transmission spectrum and then by a modeled solar irradiance spectrum; or (2) a radiance spectrum of the white SCCT taken close in time to the surface observation, as is done with Mastcam-Z calibration [8].This poster will show initial VISIR data acquired on Mars, compared with test and performance data obtained at Paris Observatory, LANL, and JPL. As of this writing, the planned observations during the first ~30 sols include spectra of the white and black SCCTs, and at least one Mars target spectrum.[1] Farley et al. (2020), Space Sci. Rev. 216, 142. [2] Wiens et al. (2020) Space Sci. Rev. 216, in press, [3] Maurice et al. (2020) Space Sci. Rev. 216,in press, [4] Manrique et al. (2020) Space Sci. Rev. 216, 8, 1-27; [5] Cousin et al. (2021) this meeting [6] Fouchet et al. (2021) Icarus, in prep. [7] Royer et al. (2020) Rev. Scient. Instrum. 91, 063105. [8] Bell, J.F. et al. (2021), Space Sci. Rev, in press.

NASA/Mars2020 and ESA/ExoMars missions will look for traces of present or past life on Mars. To do so, both Perseverance and Rosalind Franklin rovers have been equipped with a wide set of spectroscopic systems to investigate the geochemistry and mineralogy of Martian rocks and soils. As spectroscopic techniques are acquiring an increasing importance in the field of Mars exploration, many research groups are trying to estimate and optimize their potential scientific return by carrying out representative analytical studies in the laboratory.In this framework, PTAL is a research project founded by the European Commission through the H2020 program, which is aimed to provide the scientific community with a novel library of terrestrial analogue materials that have been selected based on their similarity to well-known Martian geological contexts. Planned to be released to public on January 2022, the PTAL platform (http://erica.uva.es/PTAL/) will provide future users with access to complementary spectroscopic and diffractometric data gathered from over 100 terrestrial analogues.In detail, the XRD analysis of each analogue was carried out to gather a reliable overview of samples mineralogy. Then, LIBS, IR and Raman spectrometers were used to collect additional elemental and molecular data, these being the key analytical tools onboard NASA/Perseverance and ESA/Rosalind Franklin rovers. Beside the use of commercial spectrometers, the RLS ExoMars Simulator, the MicrOmega-Flight (FS) (Spare Model) and the ChemCam-FS were also employed to collect LIBS, Raman and NIR spectra (respectively) qualitatively comparable to those that will soon gathered on Mars.In addition to analytical data, the PTAL platform will also provide direct access to a dedicated software (SpectPro) for spectral visualization and treatment [1]To conclude, future users can also request physical access to the terrestrial analogues, so that the data contained in the PTAL library can be combined with further analysis in the laboratory.To obtain further information about the PTAL project, please use the QR code provided in Figure 01.Figure 01: PTAL QR codeAcknowledgements: This work is financed through the European Research Council in the H2020- COMPET-2015 programme (grant 687302) and the Ministry of Economy and Competitiveness (MINECO, grant PID2019-107442RB-C31).References: [1] Saiz J. et al., (2019) EGU general Assembly, 21, 17904.

Analyses of meteorites and theoretical models indicate that some carbonaceous near-Earth asteroids may have been thermally altered due to radiative heating during close approaches to the Sun1–3. However, the lack of direct measurements on the subsurface doesn’t allow us to distinguish thermal alteration due to radiative heating from parent-body processes. In April 2019, the Hayabusa2 mission successfully completed an artificial impact experiment on the carbonaceous near-Earth asteroid (162173) Ryugu4,5, which provided an opportunity to investigate exposed subsurface material and test potential effects of radiative heating. Here we report observations of Ryugu’s subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. The strength and shape of the OH feature suggests that the subsurface material experienced heating above 300 °C, similar to the surface. In contrast, thermophysical modelling indicates that radiative heating cannot increase the temperature above 200 °C at the estimated excavation depth of 1 m, even at the smallest heliocentric distance possible for Ryugu. This supports the hypothesis that primary thermal alteration occurred on Ryugu’s parent body. Hayabusa2 created an artificial crater on Ryugu to analyse the subsurficial material of the asteroid. Results show that the subsurface is more hydrated than the surface. It experienced alteration processes that can be traced back to Ryugu’s parent body.

The SuperCam instrument suite provides the Mars 2020 rover, Perseverance, with a number of versatile remote-sensing techniques that can be used at long distance as well as within the robotic-arm workspace. These include laser-induced breakdown spectroscopy (LIBS), remote time-resolved Raman and luminescence spectroscopies, and visible and infrared (VISIR; separately referred to as VIS and IR) reflectance spectroscopy. A remote micro-imager (RMI) provides high-resolution color context imaging, and a microphone can be used as a stand-alone tool for environmental studies or to determine physical properties of rocks and soils from shock waves of laser-produced plasmas. SuperCam is built in three parts: The mast unit (MU), consisting of the laser, telescope, RMI, IR spectrometer, and associated electronics, is described in a companion paper. The on-board calibration targets are described in another companion paper. Here we describe SuperCam's body unit (BU) and testing of the integrated instrument. The BU, mounted inside the rover body, receives light from the MU via a 5.8 m optical fiber. The light is split into three wavelength bands by a demultiplexer, and is routed via fiber bundles to three optical spectrometers, two of which (UV and violet; 245-340 and 385-465 nm) are crossed Czerny-Turner reflection spectrometers, nearly identical to their counterparts on ChemCam. The third is a high-efficiency transmission spectrometer containing an optical intensifier capable of gating exposures to 100 ns or longer, with variable delay times relative to the laser pulse. This spectrometer covers 535-853 nm ( 105 - 7070 cm − 1 Raman shift relative to the 532 nm green laser beam) with 12 cm − 1 full-width at half-maximum peak resolution in the Raman fingerprint region. The BU electronics boards interface with the rover and control the instrument, returning data to the rover. Thermal systems maintain a warm temperature during cruise to Mars to avoid contamination on the optics, and cool the detectors during operations on Mars. Results obtained with the integrated instrument demonstrate its capabilities for LIBS, for which a library of 332 standards was developed. Examples of Raman and VISIR spectroscopy are shown, demonstrating clear mineral identification with both techniques. Luminescence spectra demonstrate the utility of having both spectral and temporal dimensions. Finally, RMI and microphone tests on the rover demonstrate the capabilities of these subsystems as well., Proyecto MINECO Retos de la Sociedad. Ref. ESP2017-87690-C3-1-R

Oxia Planum is a Noachian plain on Mars. It was chosen as the final landing site for in situ studies by ExoMars 2022 rover. The main scientific objectives of the mission are to understand the mineralogy and aqueous evolution of ancient Mars with relevance to habitability. Oxia is covered by vast deposits of Fe,Mg-phyllosilicates, but the exact nature of these deposits is not yet fully understood. We performed a survey of potential terrestrial analog rocks, and here we show combined mineralogical characterization of these rocks with their near-infrared spectral analysis. Samples from two terrestrial sites were studied: (1) vermiculitized chlorite-schists from Otago, New Zealand, which underwent an alteration process without significant oxidation; and (2) basaltic tuffs from Granby, Massachusetts, USA, with Fe-rich clays filling amygdales of supposedly hydrothermal origin. Both analogues are incorporated into the newly built Planetary Terrestrial Analogue Library (PTAL) collection. Oxia bedrock clay-rich deposits are spectrally matched best by a well-crystallized trioctahedral vermiculite/saponite mixture from the basaltic tuff, although the contribution of saponite must be minor. Otago vermiculite is a good analogue to Oxia vermiculite in terms of overall mineralogy and Fe content. However, spectral inconsistencies related to the Al content in the Otago clays indicate that illitization of vermiculite, which results from postalteration oxidation, did not occur at Oxia. This implies limited water/rock interactions and reducing conditions during deposition of sediments now constituting the bedrock at Oxia. Whereas the spectral match does not conclusively imply the mineralogy, trioctahedral vermiculite should be considered a likely mineral component of the bedrock unit at Oxia Planum. Vermiculite has great potential to store organic matter, and the postdeposition geological context of Oxia Planum derived from understanding of environmental conditions in analog sites is promising for organic matter preservation.

International audience; The Planetary Terrestrial Analogues Library (PTAL) is a dedicated lithological collection that currently consists of 102 terrestrial rock samples selected to be possible Mars analogues. The ultimate goal is improving future remote mineralogical and petrological analysis on Mars and other planetary bodies based on selected analysis such as Near- Infrared Reflectance Spectroscopy (NIR), Raman spectroscopy, Laser Induced Breakdown Spectroscopy (LIBS) and X-ray diffraction (XRD). Most international standards applied in the remote martian mineralogical and petrological analysis have so far been based on single, pure mineral analysis, with minimal interferences from other naturally occurring minerals. Here we present detailed lithological sample evaluations based on field appearance along with optical and XRD analysis of key terrestrial rock types. The detailed mineralogical and petrological descriptions give good basis for more complete lithological understanding. In combination with NIR, LIBS and Raman analysis of the very same samples PTAL aims at improving mineralogical and petrographical information from future rovers on Mars e.g. NASA's Mars2020-Perseverance and ESA and Roscosmos's ExoMars - Rosalind Franklin. The PTAL sample collection covers exclusively collected volcanic, magmatic and various sedimentary rocks and regoliths from well-known locations all over the world. These samples have a general composition comparable to what is currently known from Mars. The strength of this sample collection is its origin as common whole rock samples, in which minerals occur in their natural settings. It thereby allows studying possible detection interferences and a comparison of the sensitivity of the different techniques. The collection, in addition, forms the base for various alteration studies to better understand and explain alteration and weathering conditions on Mars. The complete results and sample preparations will be available to all scientists interested.

We evaluated the effectiveness of the ExoMars Raman laser spectrometer (RLS) to determine the degree of serpentinization of olivine-rich units on Mars. We selected terrestrial analogs of martian ultramafic rocks from the Leka Ophiolite Complex (LOC) and analyzed them with both laboratory and flight-like analytical instruments. We first studied the mineralogical composition of the samples (mostly olivine and serpentine) with state-of-the-art diffractometric (X-ray diffractometry [XRD]) and spectroscopic (Raman, near-infrared spectroscopy [NIR]) laboratory systems. We compared these results with those obtained using our RLS ExoMars Simulator. Our work shows that the RLS ExoMars Simulator successfully identified all major phases. Moreover, when emulating the automatic operating mode of the flight instrument, the RLS ExoMars Simulator also detected several minor compounds (pyroxene and brucite), some of which were not observed by NIR and XRD (e.g., calcite). Thereafter, we produced RLS-dedicated calibration curves (R2 between 0.9993 and 0.9995 with an uncertainty between ±3.0% and ±5.2% with a confidence interval of 95%) to estimate the relative content of olivine and serpentine in the samples. Our results show that RLS can be very effective in identifying serpentine, a scientific target of primary importance for the potential detection of biosignatures on Mars—the main objective of the ExoMars rover mission., Proyecto MINECO Retos de la Sociedad. Ref. ESP2017-87690-C3-1-R

Icy bodies are the most numerous and diverse bodies in the Solar System, but only a few have been visited or will be visited by a space probe. The Galilean satellites are one of those, especially Ganymede which is the primary target of the future L-class mission JUICE (launch scheduled in 2022) in ESA’s Cosmic Vision programme. Ganymede's surface visually exhibits an important geological diversity, with young bright areas to older dark terrains. This diversity also expresses itself through the moon’s surface composition, which was studied extensively in situ by the NIMS instrument of the Galileo mission (NASA) in the late 90s; like the majority of giant planet satellites, Ganymede's surface is dominated by H2O-ice and some non-icy components, very likely hydrated salts based on the distorted shape of the spectral signatures (McCord et al., 2001). However, this binary composition has been obtained with a spectral sampling (~25 µm) not allowing to detect specific absorptions for the non-icy materials, thus not allowing their identification. Hence, many questions about Ganymede’s surface composition remain unanswered while important technical advances have been made since. In preparation of the JUICE mission, and specifically of the near-infrared imaging spectrometer MAJIS of the JUICE mission, a ground-based campaign was performed using an instrument with a much finer, i.e. better, spectral sampling: SINFONI (SINgle Faint Object Near-IR Investigation). SINFONI is installed on the UT4 of the Very Large Telescope (VLT hereafter) at the European Southern Observatory (ESO hereafter) in Chile. It combines one adaptive optics module and an integral field spectrometer operating in the near-infrared covering from the beginning of the J-band (~1.1 µm) to the end of the K-band (~2.45 µm). Here we present the results derived from the analysis and the modeling of four observations acquired at different dates, from October 2012 to March 2015, all covering the 1.45 – 2.45 µm wavelength range with a spectral resolution about 0.5 µm and a spatial sampling of 12.5 x 12.5 mas2. These results were recently published in Icarus (Ligier et al., 2019). The first result we obtained concerns the physical properties of Ganymede’s surface. Indeed, the data reduction process highlights that the Lambertian model is not sufficient to remove the photometric effects due to observations geometry. Instead, the Oren-Nayar model (Oren & Nayar, 1994), which generalizes the Lambertian law for rough surfaces, produces excellent results where no inclination residuals are observed up to inclination angles around 65°. The quality of the photometric correction is thus used as proxy to infer Ganymede’s surface roughness: from 16° ± 6° to 21° ± 6° depending on the observations. Then, concerning the surface composition of the moon, our modeling confirms that it is dominated by H2O-ice, predominantly the crystalline form. The abundance maps of the ice show two main patterns: (1) a latitudinal gradient in terms of abundance, with large polar caps, and (2) a latitudinal gradient in terms of grain size, where the smaller grains (>50 µm) are located at the highest latitudes, showing a sharp transition around ±35°N coinciding with the transition between open and closed field lines of Ganymede’s own magnetic field (figure 1a). Ice sublimation explains this distribution, redistributing H2O-ice from the “hot” equator to the colder poles, very likely redeposited as finer grains. Apart from the ice, another major compound is required to fit Ganymede’s spectra: a darkening agent. Similarly to previous studies, this darkening agent could not be identified, but we were able to provide new constraints on it. First of all, this unknown material cannot be organic matter since its reflectance level, about 0.25, is more or less five times higher than that of organic matter. Instead, the reflectance level suggests a silicate-type material, as already mentioned in a previous study about Callisto (Calvin & Clark, 1991). Its abundance map shows the highest abundances (up to 0.85) at equatorial latitudes in the trailing hemisphere (figure 1b). The well-known surface sputtering engendered by Jupiter’s magnetosphere is the simplest process to explain such distribution. Even with the magnetic field of the moon, it is possible for corotating singly-charged ions to become neutralized near the moon and continue to the surface as neutrals, sputtering mostly around the trailing apex. Last but not least, our study highlights the necessity of secondary species, i.e. >10% overall, to better fit the measurements: sulfuric acid hydrate and salts, likely sulfates and chlorinated. While the sulfuric acid hydrate is, like H2O-ice, mostly located at high latitudes (figure 1c), the abundance map of the salts shows a heterogeneous distribution which seems neither related to the Jovian magnetospheric bombardment nor craters (figure 1d). These species are mostly detected on bright grooved terrains surrounding darker areas. Endogenous processes, such as freezing of upwelling fluids going through the moon’s ice shell, may explain this heterogeneous distribution.

The Planetary Terrestrial Analogues Library project aims to build and exploit a spectral data base for the characterization of the mineralogical and geological evolution of terrestrial planets and small Solar System bodies. Basis for the library is our collection of natural field-collected and artificial planetary (often Martian) analogue materials as well as materials, which have been altered in laboratory experiments. All samples were characterized by XRD, thin sections as base and as input for the spectral library with standard commercial and dedicated spacecraft instrumentation (NIR, RAMAN, LIBS) under laboratory conditions. The database will allow users to jointly interpret laboratory results and newly gathered in-situ or remote sensing data using instruments (LIBS, NIR, Raman) on board of current and future space missions (e.g., Hayabusa-2, Curiosity, ExoMars, Mars2020). The main aim of the database is the use of spectra stored for purposes related to comparison, identification, quantification and spectral calculation when spectroscopic instruments such as NIR, Raman and LIBS operate in planetary missions and/or analyzing materials in the field or in the laboratory. This database features spectral tools allowing for the spectral data treatment implementation plans are the integration of the database management and algorithms in an end-user platform with graphical interfaces for the use of the data and analyzing tools. The public release of the Planetary Terrestrial Analogues Library will be at the end of year 2020. We will have a demonstration and tutorial during the EGU-GA 2020.Acknowledgements: This project is financed through the European Research Council in the H2020-COMPET-2015 programme (grant 687302).

In the present work, NIR, LIBS, Raman and XRD techniques have been complementarily used to carry out a comprehensive characterization of a terrestrial analogue selected from the Chesapeake Bay Impact Structure (CBIS). The obtained data clearly highlight the key role of Raman spectroscopy in the detection of minor and trace compounds, through which inferences about geological processes occurred in the CBIS can be extrapolated. Beside the use of commercial systems, further Raman analyses were performed by the Raman Laser Spectrometer (RLS) ExoMars Simulator. This instrument representsthe most reliable tool to effectively predict the scientific capabilities of the ExoMars/Raman system that will be deployed on Mars in 2021. By emulating the analytical procedures and operational restrictions established by the ExoMars mission rover design, it was proved that the RLS ExoMars Simulator is able to detect the amorphization of quartz, which constitutes an analytical clue of the impact origin of craters. On the other hand, the detection of barite and siderite, compounds crystallizing under hydrothermal conditions, helps to indirectly confirm the presence of water in impact targets. Furthermore, the RLS ExoMars Simulator capability of performing smart molecular mappings was also evaluated. According to the obtained results, the algorithms developed for its operation provide a great analytical advantage over most of the automatic analysis systems employed by commercial Raman instruments, encouraging its application for many additional scientific and commercial purposes., Proyecto MINECO Retos de la Sociedad. Ref. ESP2017-87690-C3-1-R

The miniaturized near-infrared hyperspectral microscope MicrOmega, on board the MASCOT lander for Hayabusa-2 mission, is designed to perform in situ measurements at the grain scale of the C-type asteroid 1999 JU3 RYUGU. MicrOmega will observe samples with a field of view of a few millimeters with a spatial sampling of 25 μm and acquire near-infrared spectra by illuminating the sample sequentially with different wavelengths from 0.99 to 3.55 μm over two spectral channels with a typical spectral sampling of 20 cm−1. The on-ground calibration of MicrOmega requires a full characterization of the nominal range of operation of the instrument, both spectral (0.99–3.55 μm) and thermal (−40 °C to +40 °C) to derive the radiometric and spectral responses combined into a 4D transfer function to convert raw signal to calibrated reflectance. This specific 4D radiometric reference gives the instrument response according to the pixel location (x,y), the wavelength and the instrument temperature. This paper reports the complex computation of the 4D radiometric reference for the 0.9–2.5 μm channel. In this spectral range, the composition of the grains of a wide variety of minerals with relevance to solar system bodies can be identified through diagnostic spectral features: mafic (pyroxene, olivine…) as well as hydrated and altered minerals that are key phases for the solar system bodies’ exploration.

The MAJIS (Moons And Jupiter Imaging Spectrometer) instrument on board the ESA JUICE (JUpiter ICy moon Explorer) mission is an imaging spectrometer operating in the VIS-NIR spectral range from 0.50 to 5.54 µm. The scientific objectives of MAJIS span from a comprehensive study of the icy satellites, with particular emphasis on Ganymede, to the Jupiter atmosphere, including its aurorae. Additional complementary science can be addressed for the Jupiter’ ring, the active satellite Io and eventually some irregular satellites, providing an important set to increase the knowledge of the whole Jupiter system, sometime referred to as a miniature solar system. The accurate measurement of radiance from the different targets, in some case particularly faint due to strong absorption features in contrast to possible high thermal background, require a cryogenic instrument operating in a severe radiation environment, with very limited power from the solar cell requiring a passive cooling. All elements translate into significant challenges in the design, qualification and testing of the instrument. In this paper we report the scientific objectives and briefly discuss the outline design of the MAJIS optical head.

Understanding the origin (volcanic or sedimentary) and timing of intercrater plains is crucial for deciphering the geological evolution of Mars. We have produced a detailed geological map of the intercrater plains north of the Hellas basin, based on images from the Mars Express High-Resolution Stereo Camera, the Mars Reconnaissance High-Resolution Imaging Science Experiment, and Context. Erosional windows and fresh impact craters provide a way of studying the lithology of intercrater plain units. They are composed predominantly of light-toned sedimentary rocks with subhorizontal bedding over a broad extent (greater than tens of kilometers), showing cross-bedding stratifications locally. The broad extent, geometry, and flat topography of these sediments favor a formation by aqueous processes (alluvial and lacustrine) rather than airfall (eolian and volcaniclastic). The Late Noachian (~3.7 Ga) sedimentary plains are locally covered by dark-toned, rough-textured lava flows of Late Hesperian age (~3.3 Ga). Fe/Mg phyllosilicates were detected within sedimentary rocks, whereas volcanic rocks contain pyroxene and lack signatures of alteration, in agreement with interpretations made from texture and morphology. In erosional windows, the superimposition of sedimentary rocks by younger volcanic flows enables the estimation of an erosion rate of ~1000 nm yr−1 during the Hesperian period (3.3–3.7 Ga). Thus, our study shows that an intense sedimentary cycle occurred on the northern rim of the Hellas basin before and during the Late Noachian, leading to the formation of widespread sedimentary plains, which were then eroded, in agreement with a gradual change in the climatic conditions in this period, and later covered by volcanic flows.

The exosphere of Ganymede is the interface region linking the moon’s icy surface to Jupiter’s magnetospheric environment. Its characterization is of key importance to achieve a full understanding of the ice alteration processes induced by the radiation environment. Several scientific instruments that will operate on board the upcoming Jupiter Icy Moons Explorer (JUICE) mission, selected by ESA in the context of its Cosmic Vision programme, have the potential to study Ganymede’s exosphere. Among them, the Moons And Jupiter Imaging Spectrometer (MAJIS) will have the chance to investigate the composition of the moon’s exospheric components and the emission of water molecules. The exospheric water density profile, as obtained from current models, is a crucial parameter for the estimation of the expected signal to noise ratio related to the actual measurement. In lack of an adequate number of Ganymede’s observations from past missions, there is a general difficulty in constraining current exosphere models which are based, in general, on different scenarios and considerations and often show large discrepancies in the estimated spatial distribution of the neutral environment. In this work, we make a preliminary estimation of the expected IR emission from exospheric water molecules, using different modelled density profiles, and we speculate on the possibility of JUICE/MAJIS to detect it. An exercise on the potential plume detection capabilities of MAJIS is also performed. The first necessary step for performing these calculations is a rough comparison of the existing models of Ganymede’s water vapor exosphere. We discuss the characteristics of the neutral environment as derived from different exospheric models available in literature, the role of the ion-surface interactions in the H2O exosphere generation, and the related implications also in view of future observations. We then use the model outputs to estimate different scenarios for the expected non-Local Thermal Equilibrium (non-LTE) emission from these molecules. The results of this study can be of help during the JUICE observation planning phase.

International audience; The large size and complexity of planetary data acquired by spacecraft during the last two decades create a demand within the planetary community for access to the archives of raw and high level data and for the tools necessary to analyze these data. Among the different targets of the Solar System, Mars is unique as the combined datasets from the Viking, Mars Global Surveyor, Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter missions provide a tremendous wealth of information that can be used to study the surface of Mars. The number and the size of the datasets require an information system to process, manage and distribute data. The Observatories of Paris Sud (OSUPS) and Lyon (OSUL) have developed a portal, called PSUP (Planetary SUrface Portal), for providing users with efficient and easy access to data products dedicated to the Martian surface. The objectives of the portal are: 1) to allow processing and downloading of data via a specific application called MarsSI (Martian surface data processing Information System); 2) to provide the visualization and merging of high level (image, spectral, and topographic) products and catalogs via a web-based user interface (MarsVisu), and 3) to distribute some of these specific high level data with an emphasis on products issued by the science teams of OSUPS and OSUL. As the MarsSI service is extensively described in a companion paper (Quantin-Nataf et al., companion paper, submitted to this special issue), the present paper focus on the general architecture and the functionalities of the web-based user interface MarsVisu. This service provides access to many data products for Mars: albedo, mineral and thermal inertia global maps from spectrometers; mosaics from imagers; image footprints and rasters from the MarsSI tool; high level specific products (defined as catalogs or vectors). MarsVisu can be used to quickly assess the visualized processed data and maps as well as identify areas that have not been mapped yet. It also allows overlapping of these data products on a virtual Martian globe, which can be difficult to use collectively. The architecture of PSUP data management layer and visualization is based on SITools2 ( Malapert and Marseille, 2012) and MIZAR (Module for Interactive visualiZation from Astronomical Repositories) respectively, two CNES generic tools developed by a joint effort between the French space agency (CNES) and French scientific laboratories. Future developments include the addition of high level products of Mars (regional geological maps, new global compositional maps…) and tools (spectra extraction from hyperspectral cubes). Ultimately, PSUP will be adapted to other planetary surfaces and space missions in which the French research institutes are involved.

International audience; 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.

BepiColombo, an European Space Agency (ESA) mission being conducted in cooperation with the Japan space agency, will explore Mercury with a set of eleven instruments onboard the spacecraft Mercury Planetary Orbiter (MPO). Among them, SIMBIO-SYS (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem) is a complex instrument that will provide images and spectra in the 400–2000 nm wavelength range of the entire surface of Mercury. Pre-flight calibration of the SYMBIO-SYS instrument is mandatory for reliable scientific interpretation of images and spectra returned from the planet Mercury. This paper presents the calibration device designed and implemented for the specific requirements of this instrument. It mainly consists of a thermal vacuum chamber simulating the space environment, an optical bench collecting calibration sources and optical elements that simulate the conditions of Mercury observations, mechanical interfaces used for positioning the three channels inside the vacuum chamber, thermal interfaces to explore the operating temperatures, computer interfaces that allow to communicate with both the instrument and the calibration elements and synchronize the calibrations sequences with the status of the calibration device. As the major goal is the characterization of the radiometric performances of the three channels of SIMBIO-SYS, radiometric performances of the test setup evaluated by simulations and measurements are emphasized.

The Mawrth Vallis region is covered by some of the largest phyllosilicate-rich outcrops on Mars, making it a unique window into the past history of Mars in terms of water alteration, potential habitability, and the search for past life. A landing ellipse had been proposed for the Curiosity rover. This area has been extensively observed by the High Resolution Imaging Science Experiment and the Compact Reconnaissance Imaging Spectrometer for Mars, offering the possibility to produce geologic, structural, and topographic maps at very high resolution. These observations provide an unprecedented detailed context of the rocks at Mawrth Vallis, in terms of deposition, alteration, erosion, and mechanical constraints. Our analyses demonstrate the presence of a variety of alteration environments on the surface and readily accessible to a rover, the presence of flowing water at the surface postdating the formation of the clay-rich units, and evidence for probable circulation of fluids in the rocks at different depths. These rocks undergo continuous erosion, creating fresh outcrops where potential biomarkers may have been preserved. The diversity of aqueous environments over geological time coupled to excellent preservation properties make the area a very strong candidate for future robotic investigation on Mars, like the NASA Mars 2020 mission.

The objective of this study is to identify and map spectral analogues of some key martian meteorites (basaltic shergottites Los Angeles, Shergotty, QUE 94201, lherzolitic shergottite ALH A77005, Nakhla, Chassigny and the orthopyroxenite ALH 84001) in order to localize terrain candidates for their source regions. We develop a best fit procedure to reproduce the near-infrared (NIR) spectral properties of the martian surface as seen by the hyperspectral imaging spectrometer OMEGA/MEx from the NIR spectra of the martian meteorites. The fitting process is tested and validated, and Root Mean Square (RMS) global maps for each meteorite are obtained. It is found that basaltic shergottites have NIR spectral properties the most representative of the martian surface with the best spectral analogues found in early Hesperian volcanic provinces. Sites with spectral properties similar to those of ALH A77005 are scarce. They are mainly localized in olivine-bearing regions such as Nili Fossae and small Noachian/early Hesperian terrains. The only plausible source region candidate for Chassigny is the Nili Patera caldera dated to 1.6 Ga. Widespread spectral analogues for the ALH 84001 meteorite are found northeast of Syrtis Major and northwest of the Hellas basin. While this distribution is in agreement with the low-calcium-pyroxene-rich composition and old age (4.1 Ga) of this meteorite, the modal mineralogy of these candidates is not consistent with that of this meteorite. No convincing spectral analogue is found for the Amazonian-aged Nakhla meteorite suggesting that its olivine/high-calcium-pyroxene-rich composition could be representative of the Amazonian terrains buried under dust. Finally, some young rayed craters are proposed as possible candidates for source craters of the studied martian meteorites.

The observations of the surface of 4 Vesta by the Visible and Infrared Mapping Spectrometer (VIR) onboard the Dawn spacecraft reveals that its composition is dominated by pyroxenes with olivine in very localized spots. To derive new constraints on the surface composition of the asteroid, we apply a scattering model to VIR reflectance spectra. The model is first calibrated by performing a non-linear deconvolution of laboratory spectra of mineral mixtures and howardite, eucrite, diogenite (HED) meteorites. Abundance estimates of minerals are accurate to within 15–25% for the analyzed samples, while the estimated particle sizes are within the intervals of actual sizes. Grain size effects complicate spectral deconvolution and estimation of modal abundances of samples (both HED and mineral mixtures) that contain olivine. The magnesium-rich olivine detection threshold is 10–20% for large grain sizes (100s μm) and several 10s% for small grain sizes (

Early Mars (>3 Ga) underwent aqueous alteration as evidenced by fluvial/lacustrine morphologies and the recent discovery of widespread hydrous clays. Despite compelling evidence for diverse and localized aqueous environments, the possibility for sustained liquid water globally on the martian surface and over geological timescales is still highly debated. Instead, a durably cold and dry Mars scenario is often proposed. By studying specific Fe/Mg and Al-rich clay stratigraphies on Mars by means of a planetary scale orbital investigation, we present new evidence that Mars experienced an early era (>3.7 Ga) of widespread aqueous alteration consistent with surface weathering.

The formation of the silicate mineral anorthosite is thought to require magmatic processes that are not expected on Mars because of its predominately mafic terrains. Localized spectral detections by the Mars Reconnaissance Orbiter are consistent with anorthosite, suggestive of ancient intrusive igneous processes similar to those active on Earth. The mineralogical diversity preserved on ancient terrains of Mars provides insights into the planet’s early geological state and subsequent evolution. The martian crust is predominantly composed of mafic rocks with low silica contents1,2,3,4,5,6, with the exception of a few localized volcanic sequences that indicate some compositional evolution towards compositions richer in silicate minerals2. Anorthosite, which is dominated by the silicate mineral plagioclase, is rare in the Solar System. It is thought to require an evolved magmatic source in which lighter elements have been concentrated. Anorthosite has been observed previously only on Earth within localized continental plutons of intrusive igneous origin7, and more widely on the Moon8 where the anorthositic highland crust is thought to derive from crystallization of a primordial magma ocean9,10. Using near-infrared spectral data obtained by the Mars Reconnaissance Orbiter, we report the detection of iron-bearing plagioclase-rich rocks at eight sites in the southern highlands of Mars with a spectral signature consistent with ferroan anorthosites. The paucity of detections suggests a localized plutonic origin similar to terrestrial anorthosites, although a lunar-like global anorthosite crust on early Mars cannot be entirely excluded. Our detections of anorthositic compositions at several locations on the martian surface suggest that magmatic processes that produce highly evolved melts were active on ancient Mars.

[1] There is ample evidence of both ancient and long-lasting fluvial activity and chemical alteration in the Libya Montes region south of Isidis Basin. The region hosts Noachian to Amazonian aged surface rocks with extensive outcrops of olivine- and pyroxene-bearing material. Libya Montes also features surface outcrops and/or deposits hosting Fe/Mg-smectite, Fe/Mg-smectite mixed with carbonate and/or other Fe/Mg-rich phyllosilicates, and Al-smectite. These units likely formed through chemical alteration connected with hydrothermal activity resulting from the formation of the Isidis Basin and/or the pervasive fluvial activity throughout this region. The morphology and stratigraphy of the aqueous and mafic minerals are described using High Resolution Imaging Science Experiment and High Resolution Stereo Camera derived digital terrain models. Analyses of the Compact Reconnaissance Imaging Spectrometer for Mars spectra show variations in the chemistry of the Fe/Mg-smectite from nontronite-like exposures with spectral features near 2.29 and 2.4 µm more consistent with Fe3+2OH groups in the mineral structure, and saponite-like outcrops with spectral features near 2.31 and 2.38 µm characteristic of Mg2+3OH groups. These Fe/Mg-smectite bearing materials also have bands near 1.9 µm due to H2O and near 2.5 µm that could be due to the smectite, other phyllosilicates, and carbonates. All regions exhibiting carbonate features near 3.4–3.5 µm also have features consistent with the presence of olivine and Fe/Mg-smectite, indicating that the carbonate signatures occur in rocks likely containing a mixture of these minerals. The Al-smectite-bearing rocks have bands near 1.41, 1.91, and 2.19 µm that are more consistent with beidellite than other Al-phyllosilicates, indicating a higher-temperature or diagenetically processed origin for this material. Our interpretation of the geologic history of this region is that ancient Noachian basaltic crustal materials experienced extensive aqueous alteration at the time of the Isidis impact, during which the montes were also formed, followed by emplacement of a rough olivine-rich lava or melt, and finally the smooth pyroxene-bearing caprock unit.

Near infrared imaging spectrometers are key tools to investigate planetary surfaces in the Solar System. By coupling spectral and spatial information, they give access to the composition and morphology of the planets' surfaces which in turn provide insight into the geological state and history of the body. Processing and interpreting their datasets is however challenging owing to the very large amount of data they produce, a small subset of which contain relevant information, but also to numerous sources of errors, due to the instruments themselves or to observational biases, which further complicate the extraction of interesting but subtle spectral features. Collectively, these limitations have motivated the development of a set of tools that tackle these issues to facilitate the extraction of mineralogical information. The tools described here are successfully applied to the CRISM imaging spectrometer orbiting Mars in the search for hydrated silicates. An automated extraction of the hydrated silica signatures is performed at high accuracy and the discovery of a new mineral on Mars, epidote, is reported thanks to these new data reduction and analysis strategies.

[1] We present the distribution of olivine on Mars, derived from spectral parameters based on the 1 µm olivine absorption band. The olivine can be defined with respect to two spectral end-members: type 1 corresponds to olivine with low iron content and/or small grain size and/or small abundance, and type 2, which corresponds to olivine with higher iron content and/or larger grain size and/or larger abundance. The spatial and statistical analysis of the global olivine distribution points out five major geological settings where olivine is detected: (1) Early Hesperian olivine-bearing smooth crater floors and flat intercrater plains throughout the southern highlands; (2) olivine deposits around the three main basins Argyre, Hellas, and Isidis; (3) olivine in intercrater dunes, crater ejecta, or extended deposits in the northern plains; (4) olivine associated with outcrops and sand in the floor of Valles Marineris; and (5) olivine-bearing butte outcrops in the vicinity of Hellas. The geological context, the age, and the composition of the olivine detections associated with these five major geological settings are detailed. Their origin and the implication of their occurrence on the composition of the Martian mantle and crust, as well as on the evolution of Mars volcanism are discussed.

International audience; Liquid water may exist on the Martian surface today, albeit transiently and in a metastable state under the low atmospheric surface pressure. However, the identification of liquid water on Mars from observed morphological changes is hampered by our limited understanding of how metastable liquids interact with sediments. Here, we present lab experiments in which a block of ice melts and seeps into underlying sediment, and the resulting downslope fluid propagation and sediment transport are tracked. In experiments at Martian surface pressure, we find that pure water boils as it percolates into the sediment, inducing grain saltation and leading to wholesale slope destabilization: a hybrid flow mechanism involving both wet and dry processes. For metastable brines, which are more stable under Martian conditions than pure water, saltation intensity and geomorphological impact are reduced; however, we observed channel formation in some briny flow experiments that may be analogous to morphologies observed on Mars. In contrast, under terrestrial-like experimental conditions, there is little morphological impact of seeping water or brine, which are both stable. We propose that the hybrid flow mechanism operating in our experiments under Martian surface pressure could explain observed Martian surface changes that were originally interpreted as the products of either dry or wet processes.

Clays form on Earth by near-surface weathering, precipitation in water bodies within basins, hydrothermal alteration (volcanic- or impact-induced), diagenesis, metamorphism, and magmatic precipitation. Diverse clay minerals have been detected from orbital investigation of terrains on Mars and are globally distributed, indicating geographically widespread aqueous alteration. Clay assemblages within deep stratigraphic units in the Martian crust include Fe/Mg smectites, chlorites and higher temperature hydrated silicates. Sedimentary clay mineral assemblages include Fe/Mg smectites, kaolinite, and sulfate, carbonate, and chloride salts. Stratigraphic sequences with multiple clay-bearing units have an upper unit with Al-clays and a lower unit with Fe/Mg-clays. The typical restriction of clay minerals to the oldest, Noachian terrains indicates a distinctive set of processes involving water-rock interaction that was prevalent early in Mars history and may have profoundly influenced the evolution of Martian geochemical systems. Current analyses of orbital data have led to the proposition of multiple clay-formation mechanisms, varying in space and time in their relative importance. These include near-surface weathering, formation in ice-dominated near-surface groundwaters, and formation by subsurface hydrothermal fluids. Near-surface, open system formation of clays would lead to fractionation of Mars’ crustal reservoir into an altered crustal reservoir and a sedimentary reservoir, potentially involving changes in the composition of Mars’ atmosphere. In contrast, formation of clays in the subsurface by either aqueous alteration or magmatic cooling would result in comparatively little geochemical fractionation or interaction of Mars’ atmospheric, crustal, and magmatic reservoirs, with the exception of long-term sequestration of water. Formation of clays within ice would have geochemical consequences intermediate between these endmembers. We outline the future analyses of orbital data, in situ measurements acquired within clay-bearing terrains, and analyses of Mars samples that are needed to more fully elucidate the mechanisms of martian clay formation and to determine the consequences for the geochemical evolution of the planet.

Gusev crater was selected as the landing site of one of the two NASA Mars Exploration Rovers because water once could have ponded within the crater and partly filled it with sediments as suggested by the presence of a feeder channel and the fluvial-lacustrine morphology of the in-filling. However, the paucity of mineralogical evidence for fluvial-lacustrine activity revealed by the Spirit rover has remained a puzzle for years. Using orbital, near-infrared imaging spectroscopy, we report the detection of phyllosilicates and carbonates within and around the landing site of Spirit on the floor of Gusev crater. Placed in their geomorphological context, these minerals shed new light on the aqueous history of this crater, and offer a framework for the Spirit in situ measurements.

The nature of strong martian crustal field sources is investigated by mapping and modeling of Mars Global Surveyor magnetometer data near Apollinaris Patera, a previously proposed volcanic source, supplemented by large-scale correlative studies. Regional mapping yields evidence for positive correlations of orbital anomalies with both Apollinaris Patera and Lucus Planum, a nearby probable extrusive pyroclastic flow deposit that is mapped as part of the Medusae Fossae Formation. Iterative forward modeling of the Apollinaris Patera magnetic anomaly assuming a source model consisting of one or more uniformly magnetized near-surface disks indicates that the source is centered approximately on the construct with a scale size several times larger and comparable to that of the Apollinaris Patera free-air gravity anomaly. A significantly lower rms deviation is obtained using a two-disk model that favors a concentration of magnetization near the construct itself. Estimates for the dipole moment per unit area of the Lucus Planum source together with maximum thicknesses of ∼3 km based on topographic and radar sounding data lead to an estimated minimum magnetization intensity of ∼50 A/m within the pyroclastic deposits. Intensities of this magnitude are similar to those obtained experimentally for Fe-rich Mars analog basalts that cooled in an oxidizing (high fO2) environment in the presence of a strong (⩾10 μT) surface field. Further evidence for the need for an oxidizing environment is provided by a broad spatial correlation of the locations of phyllosilicate exposures identified to date using Mars Express OMEGA data with areas containing strong crustal magnetic fields and valley networks in the Noachian-aged southern highlands. This indicates that the presence of liquid water, which is a major crustal oxidant, was an important factor in the formation of strong magnetic sources. The evidence discussed here for magnetic sources associated with relatively young volcanic units suggests that a martian dynamo existed during the late Noachian/early Hesperian, after the last major basin-forming impacts and the formation of the northern lowlands.

We used Thermal Emission Spectrometer (TES), Thermal Emission Imaging System (THEMIS), High-Resolution Stereo Camera (HRSC), and Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activite (OMEGA) data to assess the physical and compositional properties of the Malea Planum portion of the Circum-Hellas Volcanic Province (CHVP). Our analysis of surface materials shows that the thermal inertia decreases from north to south, and that there is greater dust cover on the flanks of the CHVP volcanoes than in their putative calderas. Local variations in thermal inertia in Malea Planum are likely due to variations in surface material caused by aeolian and periglacial/permafrost processes, whereas regional variations are likely due to seasonal deposition and sublimation of ice at higher latitudes. Spectral analysis of OMEGA data indicates the widespread presence of pyroxenes and/or olivine, particularly in the rims of craters that likely excavated volcanic materials. Dark materials occur throughout the CHVP, but are concentrated in topographic lows such as crater and caldera floors. Derivation of modal mineralogies from OMEGA data show a variation in composition of dark materials across Malea Planum: eastern dark deposits have higher olivine and low-calcium pyroxene contents, lower high-calcium pyroxene contents, and higher ratios of low-calcium to total pyroxene, relative to western dark deposits. Correlation with cratering-model age estimates suggests that the western deposits are associated with older features (3.8 Ga) than the eastern deposits (3.6 Ga), but these age differences are within uncertainties. Nevertheless, these results suggest a potential change in composition of volcanic materials in the Malea Planum portion of the CHVP with space, and possibly time.

We present an analysis comparing observations acquired by the Mars Express Observatoire pour la Mineralogie l’Eau, les Glaces et l’Activite (OMEGA) and Phoenix lander measurements. Analysis of OMEGA data provides evidence for hydrous and ferric phases at the Phoenix landing site and the surrounding regions. The 3 μm hydration band deepens with increasing latitude, along with the appearance and deepening of a 1.9 μm H2O band as latitude increases ∼60° polewards. A water content of 10–11% is derived from the OMEGA data for the optical surface at the Phoenix landing site compared to 1–2% derived for subsurface soil by Phoenix lander measurements. The hydration of these regions is best explained by surface adsorbed water onto soil grains. No evidence for carbonate or perchlorate-bearing phases is evident from OMEGA data, consistent with the relatively small abundances of these phases detected by Phoenix. The identification of spectral features consistent with hydrated phases (possibly zeolites) from OMEGA data covering regions outside the landing site and the ubiquitous ferric absorption edge suggest that chemical weathering may play a role in the arctic soils.

The Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite (OMEGA) instrument is a visible and near-infrared imaging spectrometer on board the European Mars Express (MEx) mission. The on-board calibration (OBC) performed at the beginning of observations on each orbit reveals that the photometric response of the C channel (1.0–2.5 μm) has been very stable since orbit insertion in January 2004. On the contrary the L channel (2.5–5.1 μm) response has varied significantly during the mission, and only orbits for which the response is close to nominal could be used with confidence. The spatial coverage of ice-free surfaces in this wavelength range is consequently limited to only ∼30%, mainly during northern spring and summer. This paper presents the empirical method used to derive new instrumental transfer functions (ITF) for the non-nominal orbits. This method consists of analyzing the variation of the signal between several observations of a same region acquired at nominal and non-nominal calibration states. In the cases where the mineralogy and the atmospheric conditions between the two observations are the same, the variation in reflectance spectra is only due to the ITF variation, which provides a new ITF. We then associate these new ITFs with their corresponding OBCs to model a relationship between both. The resulting model enables us to provide a new ITF for each orbit for which the OBC is available. The new ITFs derived for the entire dataset have been validated (1) through a comparison of the C and L channel global albedo trends and (2) through a comparison of the surface temperatures derived from the L channel with those calculated from the General Circulation Model (GCM) numerical simulation of the LMD released in the Martian Climate Database. The non-nominal data processed with adapted ITFs for orbits up to 3050 increase the non-icy surface coverage of Mars to ∼70% including all seasons.

Building on previous studies of volcanoes around the Hellas basin with new studies of imaging (High-Resolution Stereo Camera (HRSC), Thermal Emission Imaging System (THEMIS), Mars Orbiter Camera (MOC), High-Resolution Imaging Science Experiment (HiRISE), Context Imager (CTX)), multispectral (HRSC, Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activite (OMEGA)), topographic (Mars Orbiter Laser Altimeter (MOLA)) and gravity data, we define a new Martian volcanic province as the Circum-Hellas Volcanic Province (CHVP). With an area of >2.1 million km2, it contains the six oldest central vent volcanoes on Mars, which formed after the Hellas impact basin, between 4.0 and 3.6 Ga. These volcanoes mark a transition from the flood volcanism that formed Malea Planum ∼3.8 Ga, to localized edifice-building eruptions. The CHVP volcanoes have two general morphologies: (1) shield-like edifices (Tyrrhena, Hadriaca, and Amphitrites Paterae), and (2) caldera-like depressions surrounded by ridged plains (Peneus, Malea, and Pityusa Paterae). Positive gravity anomalies are found at Tyrrhena, Hadriaca, and Amphitrites, perhaps indicative of dense magma bodies below the surface. The lack of positive-relief edifices and weak gravity anomalies at Peneus, Malea, and Pityusa suggest a fundamental difference in their formation, styles of eruption, and/or compositions. The northernmost volcanoes, the ∼3.7–3.9 Ga Tyrrhena and Hadriaca Paterae, have low slopes, well-channeled flanks, and smooth caldera floors (at tens of meters/pixel scale), indicative of volcanoes formed from poorly consolidated pyroclastic deposits that have been modified by fluvial and aeolian erosion and deposition. The ∼3.6 Ga Amphitrites Patera also has a well-channeled flank, but it and the ∼3.8 Ga Peneus Patera are dominated by scalloped and pitted terrain, pedestal and ejecta flow craters, and a general ‘softened’ appearance. This morphology is indicative not only of surface materials subjected to periglacial processes involving water ice, but also of a surface composed of easily eroded materials such as ash and dust. The southernmost volcanoes, the ∼3.8 Ga Malea and Pityusa Paterae, have no channeled flanks, no scalloped and pitted terrain, and lack the ‘softened’ appearance of their surfaces, but they do contain pedestal and ejecta flow craters and large, smooth, bright plateaus in their central depressions. This morphology is indicative of a surface with not only a high water ice content, but also a more consolidated material that is less susceptible to degradation (relative to the other four volcanoes). We suggest that Malea and Pityusa (and possibly Peneus) Paterae are Martian equivalents to Earth's giant calderas (e.g., Yellowstone, Long Valley) that erupted large volumes of volcanic materials, and that Malea and Pityusa are probably composed of either lava flows or ignimbrites. HRSC and OMEGA spectral data indicate that dark gray to slightly red materials (often represented as blue or black pixels in HRSC color images), found in the patera floors and topographic lows throughout the CHVP, have a basaltic composition. A key issue is whether this dark material represents concentrations of underlying basaltic material eroded by various processes and exposed by aeolian winnowing, or if the material was transported from elsewhere on Mars by regional winds. Understanding the provenance of these dark materials may be the key to understanding the volcanic diversity of the Circum-Hellas Volcanic Province.

We have identified the presence of polyhydrated sulfates in association with crystalline gray hematite in outcrop units of the chaotic terrain east of Valles Marineris. The hematite is found in abundances of up to ∼18%, and is usually associated with thin (∼10's of meters) cliff-forming layers of intermediate-toned outcrops (albedo ∼ 0.15 – 0.20 ) as well as mantling deposits adjacent to the outcrops. The polyhydrated sulfates are usually restricted to the bedrock unit, and are not found in the adjacent mantling units. In analogy to the observations performed at the Opportunity landing site, we hypothesize that erosion of the sulfate/hematite-bearing outcrops leaves the hematite behind as a lag and breaks the sulfates down to wind-transportable sizes. We also find that the layered outcrops present, for the most part, embayment or on-lap relationships with respect to the hummocks that constitute the chaotic terrain, suggesting that these units were emplaced via subaqueous or aeolian deposition and/or flow after the event that formed the associated chaos. These morphological observations, in conjunction with the correlation between hematite and polyhydrated sulfates also suggest an aqueous genesis for the crystalline gray hematite in these chaotic units, and presents evidence for the action of aqueous processes after the formation of at least some of the chaotic units on Mars.