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Abstract: The Mawrth Vallis area displays some of the largest phyllosilicate-rich outcrops of Mars, on Noachian highlands. The Mawrth Vallis region is located just at the dichotomy boundary between the Noachian highlands and the younger, northern lowlands. A large, thick, layered clay-rich unit is present throughout the inter-crater plateaus. Clay-rich layers have also been identified in parts of the Mawrth Vallis and Oyama crater floors. The age of the alteration and its relationships with other processes such as fluvial activity is fundamental for estimating the timing of aqueous activity and habitability in this region, and on Mars. We have investigated the relative stratigraphy and ages of the regional plateau, of key surfaces of the inter-crater plateau, of Oyama crater''s floor and of Chryse Planitia deposits in Mawrth Vallis'' mouth to constrain the age of the clay unit and its alteration. According to the cratering model results, the main layered unit may have started forming prior to ∼4.0Ga ago, was largely deposited by ∼3.9Ga ago, and suffered erosion and redeposition up to ∼3.8Ga ago, as indicated by the latest age of the deposits on the floor of Oyama crater. Surface aqueous alteration stopped no later than 3.7–3.6Ga ago, corresponding to the age of the dark, non-altered material capping the region, and of the dark deposits in Mawrth Vallis'' mouth. This work provides useful boundaries for constraining the time period of surface or shallow sub-surface water activity in this region. This preserved window into early phases of aqueous activity on Mars gives us a unique opportunity to study an aqueous environment of exobiological interest in the early solar system. [Copyright &y& Elsevier]

The PTAL project aims at building and exploiting a database involving several analytical techniques, the Planetary Terrestrial Analogues Library, to help characterizing the mineralogical evolution of terrestrial bodies, starting with Mars. A total of 94 natural Earth rocks have been collected from selected locations around the world to get a selection of analogues for Martian geology. The PTAL library gathers a variety of igneous rocks from different plutonic and volcanic origins and compositions, associated to different environments and levels of aqueous alteration. Samples of impact craters and sedimentary units are also present. The full set of samples will be characterized with optical thin section analysis and XRD (Oslo University, Norway), NIR spectroscopy (Paris-Saclay University, France), Raman spectroscopy (Valladolid University, Spain) and LIBS (Paul Sabatier University, France). The multianalytical study used within the PTAL project provides an unique opportunity to coordinate minerals/elements detection by different techniques that are similar to the instruments onboard current and forthcoming Martian missions. Such combined analysis should give the opportunity to prepare and improve ExoMars/ESA-Roscosmos and Mars2020/NASA observations. This paper focuses only on the NIR measurements and interpretations. The diversity of the PTAL samples is well revealed by the diversity of spectra from the NIR observations. The detected minerals are representative of various formation, alteration and geochemical environments. The major diagnostic features observed are those of primary Fe2+ bearing silicates like olivine or pyroxene with low and/or high calcium content; altered silicates detected with vibrational features associated to OH and/or H 2 O and/or metal-OH features; oxides; zeolites; and carbonates. This collection brings together a set of rocks and minerals that have been reported elsewhere in the Solar System and particularly on Mars. • Building a NIR spectral library to support planetary surface exploration. • Measurements on Mars analogues: rock specimens instead of pure minerals. • Interpretations of the spectra and relevance compared to Mars geological settings. • Need of multi technique analysis to better constrain mineralogy. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The High Resolution Stereo Camera (HRSC) of ESA׳s Mars Express is designed to map and investigate the topography of Mars. The camera, in particular its Super Resolution Channel (SRC), also obtains images of Phobos and Deimos on a regular basis. As HRSC is a push broom scanning instrument with nine CCD line detectors mounted in parallel, its unique feature is the ability to obtain along-track stereo images and four colors during a single orbital pass. The sub-pixel accuracy of 3D points derived from stereo analysis allows producing DTMs with grid size of up to 50 m and height accuracy on the order of one image ground pixel and better, as well as corresponding orthoimages. Such data products have been produced systematically for approximately 40% of the surface of Mars so far, while global shape models and a near-global orthoimage mosaic could be produced for Phobos. HRSC is also unique because it bridges between laser altimetry and topography data derived from other stereo imaging instruments, and provides geodetic reference data and geological context to a variety of non-stereo datasets. This paper, in addition to an overview of the status and evolution of the experiment, provides a review of relevant methods applied for 3D reconstruction and mapping, and respective achievements. We will also review the methodology of specific approaches to science analysis based on joint analysis of DTM and orthoimage information, or benefitting from high accuracy of co-registration between multiple datasets, such as studies using multi-temporal or multi-angular observations, from the fields of geomorphology, structural geology, compositional mapping, and atmospheric science. Related exemplary results from analysis of HRSC data will be discussed. After 10 years of operation, HRSC covered about 70% of the surface by panchromatic images at 10–20 m/pixel, and about 97% at better than 100 m/pixel. As the areas with contiguous coverage by stereo data are increasingly abundant, we also present original data related to the analysis of image blocks and address methodology aspects of newly established procedures for the generation of multi-orbit DTMs and image mosaics. The current results suggest that multi-orbit DTMs with grid spacing of 50 m can be feasible for large parts of the surface, as well as brightness-adjusted image mosaics with co-registration accuracy of adjacent strips on the order of one pixel, and at the highest image resolution available. These characteristics are demonstrated by regional multi-orbit data products covering the MC-11 (East) quadrangle of Mars, representing the first prototype of a new HRSC data product level. [ABSTRACT FROM AUTHOR]

Abstract: Impact craters cover a large portion of the surface of Mars and could constitute a significant exobiology research target as their formation provided heat sources for aqueous processes. To date, only rare examples of hydrothermal alteration in craters have been reported on Mars while many studies have focused on modeling their effect. Using data from the Mars Reconnaissance Orbiter and Mars Express probes, we report the presence of hydrated minerals, mainly Fe/Mg phyllosilicates, with vermiculite as best-fit, that are found in an alluvial fan. This fan is located inside a crater located in NE Hellas region and dated to the Late Hesperian by crater counts and crosscutting relationships. The stratigraphic position of the hydrated minerals and presence of small domes interpreted as hydrothermal vents indicate that the alteration occurred in the lower level of the alluvial fan and was triggered by bottom-up alteration. These observations are best explained by a combination of snow deposition and subsequent melting eroding crater rims and forming the fan, with impact warming, which triggered the alteration at the base of the fan. This example shows that phyllosilicates are able to form late in the Martian history, especially in local niches of strong exobiological interest. It also suggests that a similar process was possible in alluvial fans of other large impact craters including those at Gale crater. [Copyright &y& Elsevier]