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FlyRadar is a project funded by the Horizon 2020 research and innovation program of the European Union. The project aims the production of a low-frequency dual-mode radar (synthetic aperture and ground penetrating) installed on board of a lightweight unmanned aerial vehicle (or drone) and their testing for future usage in Earth and planetary investigations.Currently, one of the most important issues in the study of Mars is the understanding of the so-called viscous flow features, which, according to the modern hypothesis, are debris-covered glaciers (DCG) and consist of near-surface water ice and represent part of Martian cryosphere. These glaciers could be a source of water for future human exploration in-situ, as well as a source of hydrogen and oxygen for fuel.Besides, ice of DCG contain historical records of climatic and geologic changes and can preserve ancient microbial life or even living organisms, if Mars ever harboured life. However, there are still no detailed studies on the thickness of the debris cover and the structure and thickness of DCG on Mars. The use of FlyRadar type probe on Mars could partially fill this gap. That is why one of the directions of the FlyRadar project is to test the use and capabilities of such an instrument in the study of DCG on Earth for further use on Mars.Based on the synthesized information on the mid-latitude DCS of Mars and their terrestrial analogues previously proposed in the published literature, the following types of possible analogues of the Martian DCG on Earth are considered in this work as test sites for FlyRadar surveys:1) Rock glaciers – very good external similarity of surface morphology, but low content of pure ice (up to 30%).2) DCG with maximum covered area due to ablation and slope processes – high content of pure ice (more than 80-90%), possibility of conservation ice in permafrost, but not always very good external similarity of debris-covered areas and surface morphology due to processes associated with melting and melt waters, irregular accumulation of debris material (usually only the lower part of the glacier in the ablation zone is covered by debris).3) Ice-cored moraines and parts of DCG with limited melting due to conservation of ice (partly relict) in permafrost – high content of pure ice and good preservation potential of relict ice, but the complete absence of external similarity.4) Completely DCG due to volcanic sedimentation from atmosphere (ashfall) – high content of pure ice, good preservation potential of relict ice due to permafrost, completely debris coverage of the glacier surface except for newly formed ice in the accumulation zone. Possibly, it is the closest analogue to Martian DCG.5) Pleistocene massive ground ice (possible glaciers) buried by marine and aeolian sedimentation: high content of pure ice, good preservation potential of relict ice due to permafrost, completely debris coverage of the glacier surface, but the complete absence of external similarity, since most often morphologically buried glacier is not expressed in land surface.

Introduction: This abstract deals with analysing the interaction between the ExoMars lander and the surface deformation at the touchdown in the Oxia Planum region of Mars. The analysis of ExoMars landing has been conducted by IRSPS under Thales Alenia Space Italia and ESA by means of computer simulations and physical test with a lander mock-up. The mission involves landing via retro-rockets to slow down the lander before impact. Despite the deceleration, the impact will transfer significant energies to the ground, exceeding those experienced in past missions. Landing dynamics: Several variables of the descent phase influence the impact dynamics, such as the linear and the rotational terminal speeds, the inclination along the three axes, and the mass. We employed multi-body physics simulations to translate these input parameters into touchdown dynamics and ground stresses. The parameters and topographic data have been used in Unity and MATLAB environments to simulate the impacts. According to the Engineering Constraint of the mission [1], the topography has been modelled with slope values up to 20°. Geotechnical parameters: Estimating the geotechnical characteristics of Martian soil remains a rather complex challenge. After detailed mapping of the landing ellipse and a careful identification of the surface lithologies, we simulated different lithotypes: “Regolith” (poorly-sorted sand to cobble, loose, non-lithified material), “Mudstone” (silty marl and lithified clays with low calcite content), “Sandstone” (sandstones from deltaic and fluvial environments), “Halite” (evaporites from lacustrine/flood plain and deltaic interchannels), “Tuff” (pyroclastic material) and “Basalt” (lava flows). The geotechnical parameters have been extracted from terrestrial analogues and simulants and summarised in Table 1. Geomechanical simulations: The numerical modelling of the stressed terrain has been performed with the Itasca FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) software. One hundred and eighteen different simulations have been performed, tuning the landing variables concerning the impact dynamics, the geotechnical parameters, and the topography. The input conditions of the individual tests were composed through the programming languages FLAC3D-embedded FISH and Python. Apart from “Regolith cases”, the simulations resulted in minimal and negligible displacement (below 1 mm), although it does not exclude minimal surface fracturing of the rock. The results indicate that in none of the cases did the pressures reach the bearing capacity of the lithotypes, remaining in the domain of elastic deformations. In “Regolith” cases, due to the lower capacity, the excavation of the pads reached a range of values up to 10 cm with low terrain slopes (Fig.1) and up to 20-25 cm at higher inclinations. The cases where the first impact occurs on a single pad showed the highest displacement rates, especially when the Landing Platform is inclined perpendicularly to the ground. Subsequent contacts with other pads resulted in lower displacements due to energy dissipation and impact geometry. Field test campaign: To validate the adopted methodology and get more details about the impact dynamics, a field tests campaign has been performed with a full-size mock-up of the Landing Platform. The mock-up structure replicates the same shape and physical dimensions of the real L.P. but with a mass scaled from the original to compensate for the difference in gravity (Fig.2). It is equipped with an onboard triaxial IMU, capable of recording system speed and attitude during impact. The launching system, designed to reach desired velocities and address the touchdown conditions, consists of an inclined rail of steel girders and a quick release system. As an analogue of the regolith terrain material, we used the argillitic sub-unit of the “Argille Varicolori” formation, outcropping in southern Abruzzo and Molise regions in Italy. Geotechnical laboratory tests on terrain samples confirmed that the material is a good compromise between regolith and the clay-bearing lithology observed in the landing area. The material used has been prepared and left to dry in a quarry specialised in handling such material. Surface deformation has been measured with sub-centimetric accuracy through laser scanner point clouds realised before and after the tests (Fig.3). Eight different field test scenarios have been performed and subsequently replicated in FLAC3D for comparison. The test configurations were chosen to be representative of the variability of previous geotechnical simulations. The comparison, summarised in Table 2, displays a mean percentage difference of -0.8% (standard deviation of 8.5%), reaching a maximum of -15%. Deformation rates are also compliant with the ranges observed on Mars simulations, up to 10 cm in flat terrain conditions and up to 17 cm at 20° of the slope. Conclusions: Surface deformation characterization studies have required the application of several simulations due to the wide variability of the physical, geological, and topographical factors involved. The field test campaign validated the methodology’s reliability and confirmed the expected deformation rates. The test results show that with significant thicknesses of regolith, the impact can lead to soil deformation rates ranging from five to more than twenty centimetres. Analyses of other lithotypes indicate more favourable results with negligible deformations due to not reaching the load bearing capacity. In both cases, the displacements should not reach values that compromise the onboard instrumentation, supporting landing safety in different surface conditions with a slope up to 20°. References: [1] ESA (2013). ExoMars 2018 LSS UM Ref: EXM-SCI-LSS-ESA/IKI-003, Issue: 1.0, 17 Dec. 2013

Introduction Studying planetary field analog environments is a key point in order to define the physical and chemical parameters that favor life on Earth and other planets. Terrestrial hydrothermal springs have long been considered among the most significant planetary analogs searching for traces of life on Mars [1]. Hyperspectral data have been recognised to be more suitable for the detailed mapping and identification of rocks and minerals identification of land surface, especially for minerals [2]. Notwithstanding the technological advances, hyperspectral satellites are still poorly represented in spaceborne missions for Earth Exploration compared to multispectral ones. In this context, the Italian Space Agency (ASI) EO mission named PRISMA (PRecursore IperSpettrale della Missione Applicativa, [3]) offers a great opportunity to improve the knowledge about the scientific applications of spaceborne hyperspectral data. PRISMA, launched in March 2019, includes a panchromatic and a hyperspectral camera with 239 spectral bands. Specifically, the PRISMA satellite comprises a high-spectral resolution Visible Near InfraRed (VNIR) and Short-Wave InfraRed (SWIR) imaging spectrometer, ranging 400-2500 nm, with 30 m ground sampling distance (GSD) and 5 m GSD for the panchromatic camera [4]. Our analysis with PRISMA images was mainly performed on an arid environment in a remote region of NE Ethiopia (Dallol; Long: 40.299351, Lat: 14.244367), representing an exceptional Mars analog due to diffuse hydrothermal alteration and the sulfate deposits evocative of past hydrothermal activity on Mars. This work aimed to obtain an identification map of minerals and their relative abundance using hyperspectral imaging to understand the potential of PRISMA as analog probe of Mars orbital instruments to detect and study possible analogs on Earth. Study Area Dallol is situated in the Danakil Depression, which is part of the East African Rift System. Principal geothermal features of the central crater area of Dallol are salt pillars, circular manifestations and acidic ponds. The northern and southern part is dominated by a salt dome structure and Salt pinnacles in the SW salt canyon area. The Black Mountain and the super-saline Black Lagoon, just south-southwest of Dallol, is an area of salt extrusions, geothermal manifestations and brine upflows. One advantage of this area is that the nebulosity is generally low, in fact the image selected during the dry season has a cloud coverage percentage of less than 1%. A salt suite was deposited and re-worked by hydrothermalism in the selected site. The characteristic minerals of the area are: carbonate, halite, carnallite and bischofite, anhydrite, gypsum, native sulfur of hydrothermal origin [5; 6]. Flooding episodes from the Lake Assale to the north due to intense winds acting over the flat topography of the depression. The PRISMA SWIR Land/Water band combinations on the image selected, helped us to choose the region of interest around the Dallol area. Operational Hyperspectral Processing PRISMA images have three different levels of processing. Level 2C and 2D geolocated and atmospherically corrected images were used in this work and dated 21 August 2021. it is worth noticing that the images acquired on Dallol prior to the image selected for analysis had several preprocessing problems, particularly for stripe removal. The operational hyperspectral processing is composed of three main processing steps: (1) dimensionality reduction; (2) endmember identification and (3) mineral map distribution and abundance estimation. An unexpected result was obtained by applying an additional atmospheric correction, the Internal Average Relative Reflectance with Dark Subtraction, on the L2C image already corrected during the principal component analysis (PCA). The corrected atmospheric PCA allows better highlighting of geomorphological features. As for step (1), since hyperspectral images are composed of hundreds of extremely correlated bands, it is possible, and indeed beneficial, to reduce the effective dimension of the input data by removing bad bands. Step (2) was performed using the THOR Hyperspectral Material Identification (in ENVI 5.6) to identify unknown spectral signatures by comparing them with spectral libraries. This tool considers background statistics and image endmembers and can therefore provide accurate responses and spectra plots for rare or sub-pixel targets. Finally, the Spectral Angle Mapper (SAM) and the Linear Spectral Unmixing (LSU) tools were adopted for step (3). SAM determines the spectral similarity between two spectra by calculating the angle between the spectra and treating them as vectors in a space with dimensionality equal to the number of bands. LSU is a standard technique for spectral mixture analysis that infers a set of endmembers and fractions of these, called abundances. The mineral distribution and the abundance maps are shown respectively in Fig.1 and Fig.2. Conclusion Six minerals have been recognised with the SAM classification from ENVI spectral library, in excellent agreement with the previous studies: carnallite, jarosite, kainite, polyhalite, gypsum and nontronite. The results confirm the mineralogical variability typical of the Dallol; in Fig.2, high mineral abundance values are shown in blue. The error calculated with the RMS is very low over the entire area of interest, except for the central zone where there are sulphur pools and therefore the presence of water does not favour this type of analysis. To better constrain the mineralogical mapping, future work will be conducted by a field exploration campaign to collect spectral signatures to be added to the ENVI library used, which so far could not be organised due to the ongoing civil war in Dankalia. To sum up, the study of terrestrial analogs can provide insights into the probable presence and nature of spring deposits on Mars, as well as help develop methods for classifying them from remote sensing data. PRISMA represents a valuable satellite for distinguishing not only the geometric characteristics of observed objects, but also the chemical-physical composition of the surface of the Earth. References: [1] Walter, M.R. and Des Marais, D.J., 1993. Icarus 101:129–143 [2] Chang, C.I., 2007. John Wiley & Sons. 10.1002/0470124628 [3] Candela, L., et al. 2016. IEEE international geoscience and remote sensing symposium (IGARSS), 253-256. 10.1109/IGARSS.2016.7729057 [4] Loizzo, R., et al. 2019. IEEE (IGARSS), 4503-4506. 10.1109/IGARSS.2019.8899272 [5] Cavalazzi, B., et al. 2019. Astrobiology, 19(4), 553-578. 10.1089/AST.2018.1926 [6] López-García, J.M., et al. 2020. Frontiers in Earth Science, 7, 351. 10.3389/FEART.2019.00351

Hyperspectral sensors offer the opportunity of analysing the chemical and physical composition of the remote sensed scene thanks to their ability of measuring the spectrum of the observed pixels in a large number of contiguous and narrow spectral channels [1].Despite the technological advances, hyperspectral satellites are still poorly represented in spaceborne missions for Earth Exploration compared to multispectral ones [2]. In this context, the Italian Space Agency (ASI) EO mission named PRISMA (PRecursore IperSpettrale della Missione Applicativa, [3]) offers a great opportunity to improve the knowledge about the scientific and commercial applications of spaceborne hyperspectral data. PRISMA, launched in March 2019, includes a pushbroom hyperspectral camera covering the portion of the electromagnetic spectrum ranging from 400 nm to 2500 nm with 10 nm spectral sampling. Precisely, the PRISMA satellite comprises a high-spectral resolution Visible Near InfraRed (VNIR) and Short Wave InfraRed (SWIR) imaging spectrometer with 30 m ground sampling distance (GSD) and a panchromatic camera with 5 m GSD [4].One of the critical issues in the exploitation of hyperspectral remotely sensed data is represented by the distortion effects due to the atmosphere in the radiative transfer path [5]. The products systematically produced by the PRISMA ground processor and made available to users consist of: Level 1 TOA radiometrically and geometrically calibrated radiance images; Level 2 geolocated and geocoded atmospherically corrected images. Details can be found in the PRISMA Products Specification Document [6].Our analysis of PRISMA imagery was mainly performed on an arid environment in NE Ethiopia (Dallol; Long: 40.299351, Lat: 14.244367). One advantage of this area is that the nebulosity is generally low, in fact the image selected during the dry season has a cloud coverage percentage less than 1%. In the selected site, a salt suite was deposited and re-worked by hydrothermalism. The characteristic minerals of the area are: carbonate, halite, carnallite, anhydrite, gypsum, native sulfur of hydrothermal origin (7; 8). The unique lithological and geochemical features of Dallol and, specifically, the Mesozoic and Tertiary sedimentary cover, offer the opportunity to test PRISMA data at first order to delineate carbonates from salts.The main objectives of this study are (1) to implement the atmospheric corrections for Level 1 data and compare the results with Level 2 data and (2) to test the capabilities of Prisma cubes to map an environment made of various sedimentary rocks and to differentiate and identify characteristic salt minerals.References: [1] Chang, C.I., 2007. John Wiley & Sons. DOI: 10.1002/0470124628 [2] Transon, J., et al. 2018. Remote Sensing, 10(2), 157. DOI: 10.3390/rs10020157 [3] Candela, L., et al. 2016. IEEE international geoscience and remote sensing symposium (IGARSS), 253-256. DOI: 10.1109/IGARSS.2016.7729057 [4] Loizzo, R., et al. 2019. IEEE International Geoscience and Remote Sensing Symposium (IGARSS), 4503-4506. DOI: 10.1109/IGARSS.2019.8899272 [5] Schott, J.R., 2007. Oxford University Press on Demand [6] ASI, 2020. PRISMA Products Specification Document Issue 2.1 [7] Cavalazzi, B., et al. 2019. Astrobiology, 19(4), 553-578. DOI: 10.1089/AST.2018.1926 [8] López-García, J.M., et al. 2020. Frontiers in Earth Science, 7, 351. DOI: 10.3389/FEART.2019.00351

Companies that work in the decommissioning of platforms need tools to make smarter and informed business decisions, manage and analyse business data, increase the security of workers and operate under strict environmental protection regulations. INSURE aims at assessing the feasibility of a new service to support the decommissioning of offshore installations by means of technological innovation made available throughout each process’ step. In order to accomplish this, the project gathers high-impact Italian companies bringing together the best applicable technological and scientific know-how. INSURE foresees to combine these know-hows and create a novel tool at the service of the industry to promote a better and safer approach to the operations. Targets of the INSURE project are improving workers’ safety, enhancing environmental monitorings, increasing operations’ efficiency, reducing operational costs, offering a route for future sustainability. Project targets can be achieved through the realisation of an augmented virtual reality platform (AVRP) that will be operated in support of the decommissioning process where the data acquired/transmitted by a plurality of sensors will converge. A fleet control tool integrates information from sensors installed on autonomous aerial and underwater vehicles making use of the Global Satellite Navigation Systems (GSNS) and Satellite Communications (SatCom). The convergence of top-notch technologies (augmented/virtual reality, 3D, robotics, sensors, 5G and Satellite services), together with a cloud of infrastructure, enables a fast and complete access to real-time data at very high resolution. The proposal aims to bring the actual data and information access from the Internet of Things to the Internet of Knowledge paradigm. Confrontation with national and international possible end-users produced a set of user requirements guiding the design of a feasibility study for the realisation of one specific product. The study also includes the evaluation of economic, non-economic viability and possible regulatory constraints to its realisation. The INSURE feasibility study creates the intellectual background for the further step of the process: the realisation and development of a pilot project tailored for the purpose. This combined use of novel technologies represents an innovative integrated approach applied to the management of offshore structures undergoing decommissioning or reconfiguration for other purposes. In addition, it also involves the promotion of sustainable opportunities for commercial, social and educational exploitation of areas and assets (including, for example, the ambit of eco-tourism, renewable energies, carbon capture and storage).

Virtual reality (VR) is an important tool for several applications in science, industry, and education. Previous studies have already shown how the use of VR at full scale is an effective tool for ...

The Sirente crater field (Central Italy) consists of a main, ≈130 m wide, droplet-shaped in plan view depression with a prominently elevated rim, and 30 smaller depressions in its close vicinity. It was discovered in 2002 and proposed to be of meteorite impact origin based on its geological and geomorphological similarities to known crater fields. It is developed in non-lithified lake sediments (i.e. carbonate mud). Given the age of formation in the 3rd to 5th centuries A.D., the inferred catastrophic origin was, in the media, soon related to the celestial sign (“Chi Rho”) said to have been seen by Emperor Constantine in 312 A.D. and suggested to have changed the course of both Roman and Christian history. However, the meteoritic origin is not yet confirmed and has been contested. This work presents new geophysical data on the subsurface structure of the main crater, which provides further clues around the controversy of its origin. Two roughly transversal seismic reflection profiles across the main crater reveal a deep (53 m on average), rootless, bowl-shaped structure with a poorly developed, deep-seated central mound, as well as different seismic facies representing a crater infill of disturbed material resembling the breccia lens in craters formed in rock. This survey also allowed the recognition of possible compaction-fissures and upturned strata below the rim, similar to what is known from explosion craters in porous, unconsolidated targets. Some of these structures had already been noted in published resistivity surveys (ERT). The structural features noted in this geophysical survey are consistent with the impact hypothesis and do not support other proposed mechanisms of formation such as karst or mud volcano.

As a primary tool to facilitate exchange of information, a web based shared collaborative environ- ment, the Project Management Cloud, has been set up; which serves as a project tracking system accessible to all partners. All information/documentation is therein easily accessible and kept up to date with little effort. The Fly-Radar Cloud will be actively used on a day-to-day base and will constitute the primary repository for both documents and research data.

Aeolis Dorsa is a topographic depression, ∼800 km east of Gale Crater, located along the Mars’ dichotomy boundary. This area hosts a set of fluvial sedimentary rocks displaying an exceptional record of depositional environments and fluvial channels patterns that suggest the presence of a large amount of surface and/or subsurface water. We interpreted the plain as an ancient waterlogged environment, a sedimentary basin passing into distal depositional environments. Regional mapping of the area revealed the presence of a large-scale fluvial system that points to a long-term and extensive hydrological cycle. A significant wet period with changing environmental conditions in Hesperian/Amazonian occurred in the study area diverging from the present-day climate. Our map (Main Map) contributes to the understanding of past climatic conditions on Mars. Moreover, it provides an interesting perspective for future missions looking for evidence of present-day and/or past extraterrestrial organisms as the life as we know it needs liquid water.

International audience; Titan was a mostly unknown world prior to the Cassini spacecraft’s arrival in July 2004. We review the major scientific advances made by Cassini’s Titan Radar Mapper (RADAR) during 13 years of Cassini’s exploration of Saturn and its moons. RADAR measurements revealed Titan’s surface geology, observed lakes and seas of mostly liquid methane in the polar regions, measured the depth of several lakes and seas, detected temporal changes on its surface, and provided key evidence that Titan contains an interior ocean. As a result of the Cassini mission, Titan has gone from an uncharted world to one that exhibits a variety of Earth-like geologic processes and surface-atmosphere interactions. Titan has also joined the ranks of “ocean worlds” along with Enceladus and Europa, which are prime targets for astrobiological research.

The Dallol volcano and its associated hydrothermal field are located in a remote area of the northern Danakil Depression in Ethiopia, a region only recently appraised after decades of inaccessibility due to severe political instability and the absence of infrastructure. The region is notable for hosting environments at the very edge of natural physical-chemical extremities. It is surrounded by a wide, hyperarid salt plain and is one of the hottest (average annual temperature Dallol : 36-38°C) and most acidic natural systems (pH Dallol ≈0) on Earth. Spectacular geomorphologies and mineral deposits produced by supersaturated hydrothermal waters and brines are the result of complex interactions between active and inactive hydrothermal alteration of the bedrock, sulfuric hot springs and pools, fumaroles and geysers, and recrystallization processes driven by hydrothermal waters, degassing, and rapid evaporation. The study of planetary field analog environments plays a crucial role in characterizing the physical and chemical boundaries within which life can exist on Earth and other planets. It is essential for the definition and assessment of the conditions of habitability on other planets, including the possibility for biosignature preservation and in situ testing of technologies for life detection. The Dallol area represents an excellent Mars analog environment given that the active volcanic environment, the associated diffuse hydrothermalism and hydrothermal alteration, and the vast acidic sulfate deposits are reminiscent of past hydrothermal activity on Mars. The work presented in this paper is an overview of the Dallol volcanic area and its hydrothermal field that integrates previous literature with observations and results obtained from field surveys and monitoring coupled with sample characterization. In so doing, we highlight its exceptional potential as a planetary field analog as well as a site for future astrobiological and exploration programs, This is a contribution to the Europlanet 2020 Research Infrastructure programme funded under the European Commission's Horizon 2020 programme (No. 654208

The Dallol geothermal area in the northern part of the Danakil Depression (up to 124–155 meter below sea level) is deemed one of the most extreme environments on Earth. The area is notable for being part of the Afar Depression, an incipient seafloor-spreading center located at the triple junction, between Nubian, Somali and Arabian plates, and for hosting environments at the very edge of natural physical-chemical extremities. The northern part of the Danakil Depression is dominated by the Assale salt plain (an accumulation of marine evaporite deposits) and hosts the Dallol volcano. Here, the interaction between the evaporitic deposit and the volcanisms have created the unique Dallol hot springs, which are highly acidic (pH ~ 0) and saline (saturation) with maximum temperatures ranging between 90 and 109 °C. Here we report for the first time evidence of life existing with these hot springs using a combination of morphological and molecular analyses. Ultra-small structures are shown to be entombed within mineral deposits, which are identified as members of the Order Nanohaloarchaea. The results from this study suggest the microorganisms can survive, and potential live, within this extreme environment, which has implications for understanding the limits of habitability on Earth and on (early) Mars., European Union’s Horizon 2020 research and innovation program under Grant Agreement No 654208

International audience; The entry, descent and landing of Schiaparelli, the ExoMars Entry, descent and landing Demonstrator Module (EDM), offered a rare (once-per-mission) opportunity for in situ investigations of the martian environment over a wide altitude range. The aim of the ExoMars AMELIA experiment was to exploit the Entry, Descent and Landing System (EDLS) engineering measurements for scientific investigations of Mars’ atmosphere and surface. Here we present the simulations, modelling and the planned investigations prior to the Entry, Descent and Landing (EDL) event that took place on 19th October 2016. Despite the unfortunate conclusion of the Schiaparelli mission, flight data recorded during the entry and the descent until the loss of signal, have been recovered. These flight data, although limited and affected by transmission interruptions and malfunctions, are essential for investigating the anomaly and validating the EDL operation, but can also contribute towards the partial achievement of AMELIA science objectives

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 research project ‘Moon Mapping’ has been established in 2014 between the Italian and Chinese Governments to promote cooperation and exchange between undergraduate students from both countries. The operational phase of the project started in early 2015, and will end in 2017, for a total length of three years. The main aim is to train new scholars to be able to work on different kinds of remotely-sensed data collected over the Moon surface by the Chinese space missions Chang’E-1/2. The project coordination has been assigned to the Italian Space Agency for the Italian side and to the Center of Space Exploration, China Ministry of Education, for the Chinese side. Several Chinese universities and Italian national research institutes and universities have been officially involved in this project. Six main research topics have been identified: (1) map of the solar wind ion; (2) geomorphological map of the Moon; (3) data preprocessing of Chang’E-1 mission; (4) map of element distribution; (5) establishment of 3D digital visualization system; and (6) compilation and publication of a tutorial on joint lunar mapping.

Mineral dust particles represent the most abundant component of atmospheric aerosol in terms of dry mass. They play a key role in climate and climate change, so the study of their emission processes is of utmost importance. Measurements of dust emission into the atmosphere are scarce, so that the dust load is generally estimated using models. It is known that the emission process can generate strong atmospheric electric fields. Starting from the data we acquired in the Sahara desert, here, we show for the first time that depending on the relative humidity conditions, electric fields contribute to increase up to a factor of 10 the amount of particles emitted into the atmosphere. This means that electrical forces and humidity are critical quantities in the dust emission process and should be taken into account in climate and circulation models to obtain more realistic estimations of the dust load in the atmosphere.

Imdr Regio is a volcano dominated young topographic rise of Venus whose most prominent volcanic structure, Idunn Mons, shows indications of being recently active. Despite its scientific relevance, this region has been poorly studied to date. Idunn Mons is spatially related to a rift system, Olapa Chasma, which dominates the topographic rise. The rift fractures around Idunn Mons form an “hourglass” pattern indicating a close tectonic interaction between the volcano and Olapa Chasma. The principal aim of this work is to understand whether Olapa Chasma has been tectonically active in the recent geologic past. For this purpose, we analyzed Sandel crater (45.7°S/211.7°E), an impact structure 17.9 km in diameter situated NW of Idunn Mons, and we used it as a local stratigraphic marker. Observing the variations in the radar brightness and crosscutting relationships, we produced a local geologic map of impact deposits, volcanic materials and tectonic structures surrounding the crater. Then, we used the map to reconstruct the local stratigraphy and relative ages of the materials for deciphering the temporal relations between the crater and volcano-tectonic activity. Following the existing degradation models for Venusian craters we could also estimate a time range for the formation of Sandel crater. The results show that its formation convincingly occurred during the period between 0.5 T and 0.15 T, where T is the average age of the surface of Venus. We present here a line of evidence that, at least in its last stage, the tectonic activity characterizing Olapa Chasma and Idunn Mons postdate the formation of Sandel crater. Building on the findings from previous studies, we hypothesize that not only volcanism but also the tectonic processes behind the formation of Idunn Mons and Olapa Chasma are geologically recent. For this reason, we refer to Olapa Chasma and Idunn Mons as a recently active volcano-tectonic system of Venus, which deserves to be a potential target site for future missions to Venus, including investigations of surface volcanism and seismicity.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Globorotalia bouregregensis, n. sp., is described and documented from the latest Miocene-early Pliocene sequence of the Rifian Seaway, northwest Morocco. By its short stratigraphic distribution, persistence and distinctive morphologic features, the new taxon is well differentiated within the scituline assemblage.

Finally, we would like to recognize the help and support of ESA, Roscosmos, the European states and agencies participating in the ExoMars program, and NASA. We really are doing this together for the benefit of all., The second ExoMars mission will be launched in 2020 to target an ancient location interpreted to have strong potential for past habitability and for preserving physical and chemical biosignatures (as well as abiotic/prebiotic organics). The mission will deliver a lander with instruments for atmospheric and geophysical investigations and a rover tasked with searching for signs of extinct life. The ExoMars rover will be equipped with a drill to collect material from outcrops and at depth down to 2 m. This subsurface sampling capability will provide the best chance yet to gain access to chemical biosignatures. Using the powerful Pasteur payload instruments, the ExoMars science team will conduct a holistic search for traces of life and seek corroborating geological context information., European Space Agency, Roscosmos, ExoMars program, National Aeronautics & Space Administration (NASA)

We report on the MARS2013 mission, a 4-week Mars analog field test in the northern Sahara. Nineteen experiments were conducted by a field crew in Morocco under simulated martian surface exploration conditions, supervised by a Mission Support Center in Innsbruck, Austria. A Remote Science Support team analyzed field data in near real time, providing planning input for the management of a complex system of field assets; two advanced space suit simulators, four robotic vehicles, an emergency shelter, and a stationary sensor platform in a realistic work flow were coordinated by a Flight Control Team. A dedicated flight planning group, external control centers for rover tele-operations, and a biomedical monitoring team supported the field operations. A 10 min satellite communication delay and other limitations pertinent to human planetary surface activities were introduced. The fields of research for the experiments were geology, human factors, astrobiology, robotics, tele-science, exploration, and operations research. This paper provides an overview of the geological context and environmental conditions of the test site and the mission architecture, in particular the communication infrastructure emulating the signal travel time between Earth and Mars. We report on the operational work flows and the experiments conducted, including a deployable shelter prototype for multiple-day extravehicular activities and contingency situations.

Martian caves are regarded as one of the most interesting locations in which to search for life on the planet. Data obtained during the MARS2013 expedition at Hamar Laghdad Ridge in the Tafilalt region of Morocco indicate that even small cavities can display thermal behavior that is characteristic for caves. For example, temperature in a cavity equaled 14°C±0.1°C before sunrise, which was higher than the temperature of the ambient air (10°C±0.1°C) and proximate rocks (9°C±0.1°C) at the same time. Within 30 min after sunrise, when the temperature of surrounding rocks corresponded to 15°C, this thermal relationship reversed. Measurements were conducted under simulated spaceflight conditions, including near-real-time interpretation of data that were acquired in a complex flight planning environment. We conclude that using ground-based thermal contrast measurements, in 7-14 μm band before and after sunset, is an effective method for Mars astronauts to identify caves, possibly superior to usage of space-based or ground-penetrating data.

We have developed a portable dual-wavelength laser fluorescence spectrometer as part of a multi-instrument optical probe to characterize mineral, organic, and microbial species in extreme environments. Operating at 405 and 532 nm, the instrument was originally designed for use by human explorers to produce a laser-induced fluorescence emission (L.I.F.E.) spectral database of the mineral and organic molecules found in the microbial communities of Earth's cryosphere. Recently, our team had the opportunity to explore the strengths and limitations of the instrument when it was deployed on a remote-controlled Mars analog rover. In February 2013, the instrument was deployed on board the Magma White rover platform during the MARS2013 Mars analog field mission in the Kess Kess formation near Erfoud, Morocco. During these tests, we followed tele-science work flows pertinent to Mars surface missions in a simulated spaceflight environment. We report on the L.I.F.E. instrument setup, data processing, and performance during field trials. A pilot postmission laboratory analysis determined that rock samples acquired during the field mission exhibited a fluorescence signal from the Sun-exposed side characteristic of chlorophyll a following excitation at 405 nm. A weak fluorescence response to excitation at 532 nm may have originated from another microbial photosynthetic pigment, phycoerythrin, but final assignment awaits development of a comprehensive database of mineral and organic fluorescence spectra. No chlorophyll fluorescence signal was detected from the shaded underside of the samples.

Sand dune migration is documented with a readily-available tool (Google Earth) near Chott El Gharsa, just north-west of Tozeur, Tunisia. As fiducial markers we employ a set of buildings used to portray the fictional city Mos Espa. This set of ~ 20 buildings over roughly a hectare was constructed in 1997 for the movie Star Wars Episode 1 — The Phantom Menace. The site now lies between the arms of a large “pudgy” barchan dune, which has been documented via satellite imaging in 2002, 2004, 2008 and 2009 to have moved from ~ 140 m away to only ~ 10 m away. Visits by the authors to the site in 2009 and 2011 confirm the barchan to be in a threatening position: a smaller set nearby was substantially damaged by being overrun by dunes circa 2004. The migration rate of ~ 15 m/yr decreases over the observation period, possibly as a result of increased local rainfall, and is consistent with barchan migration rates observed at other locations worldwide. The migration rate of this and two other barchans suggests sand transport of ~ 50 m3/m/yr, somewhat higher than would be suggested by traditional wind rose calculations: we explore possible reasons for this discrepancy. Because of the link to popular science fiction, the site may be of pedagogical interest in teaching remote sensing and geomorphic change. We also note that nearby playa surfaces and agricultural areas have a time-variable appearance. The site's popularity as a destination for Star Wars enthusiasts results in many photographs being posted on the internet, providing a rich set of in-situ imagery for continued monitoring in the absence of dedicated field visits.

During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (∼46.5% and ∼61% of all particles; ∼76.5 wt % and ∼89 wt % of the relative particle load). Furthermore, ∼69% and ∼82% of all lifted sand grains occurred in the first meter of the dust devils, indicating the occurrence of “sand skirts.” Both sampled dust devils were relatively small (∼15 m and ∼4–5 m in diameter) compared to dust devils in surrounding regions; nevertheless, measurements show that ∼58.5% to 73.5% of all lifted particles were small enough to go into suspension (

International audience; We highlight the role of COSPAR and the scientific community in defining and updating the framework of planetary protection. Specifically, we focus on Mars ?Special Regions,? areas where strict planetary protection measures have to be applied before a spacecraft can explore them, given the existence of environmental conditions that may be conducive to terrestrial microbial growth. We outline the history of the concept of Special Regions and inform on recent developments regarding the COSPAR policy, namely, the MEPAG SR-SAG2 review and the Academies and ESF joint committee report on Mars Special Regions. We present some new issues that necessitate the update of the current policy and provide suggestions for new definitions of Special Regions. We conclude with the current major scientific questions that remain unanswered regarding Mars Special Regions.

International audience; Gullies on terrestrial sand dunes are rare, and their presence on Mars, as well as their mechanical properties, and the quantity of fluid required for their formations currently remain poorly understood. This study focuses on gully morphologies on the Russell megadune (54.5°S; 12.7°E) using High Resolution Imaging Science Experiment (HiRISE) images and Digital Terrain Models (DTM). Based on the scenario of ground ice melting in a periglacial environment, we propose to test the hypothesis that Martian gullies on dunes are debris flows. This implies a flow with a significant proportion of liquid water (>10% in volume). We used an original method to study Martian gullies based on empirical equations from terrestrial debris flows in order to calculate the physical properties of Martians flows. We observe a decrease in viscosity induced by the relative increase of fluid concentration (from 28% to 39%) during the flow advance. The total estimated volume of eroded and deposited material range from ~14850 m3 to ~18890 m3. The volume of liquid water required to generate one gully ranges from 4450 m3 to 6900 m3. The calculated results for Martian gullies are consistent with terrestrial studies on debris flows. Based on a morphological description and on the estimated physical parameters, we propose a model for gully formation on Martian dunes. The melt water from near-surface ground ice is incorporated in the debris flow and water concentration increases during its propagation. The increase of water concentration in the debris flow can be explained by a progressive increase of water/ice content in the permafrost downstream. Consequently, the lack of a final deposit at the front of the gullies tends to demonstrate that the flow became relatively highly concentrated in liquid downstream and all the water could have been lost in the final stage of the flow. This process could explain the lack of terminal lobes at the front of the gullies. We conclude that a process of formation similar to terrestrial debris flows is plausible. The large amount of liquid water involved requires formation of Martian gullies on dunes during a warmer climatic episode.

In this work we analyze a dark erg on Mars that could be considered a mega-dune (draa) where secondary dunes of different morphology are superposed over a main crescent-shaped bedform (primary dune). The presence of a complex, multi-directional wind regime is indicated as one of the main causes for the accumulation of a tall draa, presenting an analogy to the Great Sand Dunes in Colorado. In both cases, main regional winds from the SW blow in opposition to winds from the NE which are enhanced by the topography. Such a complex wind regime leads to the development of star and reversing dunes and is accurately predicted by atmospheric models on a regional and local scale. Signs of activity in the form of grainflow scars are also noted over the slip faces of many dunes, suggesting that easterly winds are actively shaping the study draa in the present-day climatic setting. The presence of this draa on Mars suggests a complex interaction between regional and local topographically controlled flows and a consistent availability of sand. The future study of an analogue terrestrial site such as the Great Sand Dunes could be fundamental for understanding the evolution of similar Martian dune fields. Copyright © 2012 John Wiley & Sons, Ltd.

International audience; Iron-framboids in the context of a Middle Devonian, hydrocarbon-seep conical mound (Anti-Atlas, Morocco) have been thoroughly investigated through a combination of techniques, including optical and high resolution scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, Raman microscopy and time-of-flight secondary ion mass spectroscopy. Framboids occur embedded in laminated carbonates of the mound and are precipitated along the veins that crosscut it and served as the conduits for (channeled) reduced hydrocarbon-rich fluids. The morphology, structure, and composition of the framboids contribute to the reconstruction of the complex interplay between the advected fluids and the associated biological and/or abiological processes. A comparison of our dataset with that from modern framboids formed under similar conditions indicates that the Fe-rich framboids represent replaced primary pyrite framboids produced as a consequence of bacterial sulfate reduction and the anaerobic oxidation of methane.

We report the detection of mound-like landforms interpreted as mud volcanoes within Firsoff crater, in the Arabia Terra region of Mars. The mounds stratigraphically overlie layered deposits within the crater, which consist of high albedo well-bedded deposits disrupted in meter-sized polygons. Hundreds of mounds are observed on the crater floor, as isolated or composite subcircular cones 100–500 m in diameter and tens of meters high. More than one third of the mounds (35%) have subcircular depressions 5–39 m in diameter at their apices that we interpret as vents. The mounds consist of meter-sized boulders of high albedo, embedded in an apparently finer-grained unit; we interpret these deposits as mud volcanic breccia, containing boulders of reworked light-toned layered deposits carried upward from deeper portions of the succession. The mounds are mainly located near the rim-bordering faults and in places aligned with fractures, suggesting subsurface pathways for fluid migration. The mounds are interpreted as fossil mud volcanoes, recording the upward migration of overpressured fluids through the crater infill from deeper crustal sources, localized by impact-related faults. The geological conditions and processes that might have controlled sedimentary expulsion on Mars are discussed. Mud volcanism has most of its controls in the subsurface. As a consequence, subsurface fluid flow processes could be expected in other craters within Arabia Terra and are less likely in higher, adjacent highland terrains.

We discuss in this paper possible roles of methane and carbon dioxide in geological processes on Mars. These volatiles in the martian crust may migrate upward from their sources either directly or via various traps (structural, sedimentary, ground ice, gas hydrates). They are then likely emitted to the atmosphere by seepage or through diverse vent structures. Though gas hydrates have never been directly detected on Mars, theoretical studies favor their presence in the crust and polar caps; they could have played an important role as significant gas reservoirs in the subsurface. The martian gas hydrates would possibly be a binary system of methane and carbon dioxide occupying clathrate cavities. Landforms such as mud volcanoes with well-known linkage to gas venting are extensively distributed on Earth, and methane is the primary gas involved. Thus, identification of these landforms on Mars could suggest that methane and possibly carbon dioxide have contributed to geological processes of the planet. For example, we present a newly identified field in Chryse Planitia where features closely resembling terrestrial mud volcanoes occur widely, though with no observable activity. We also present results of a preliminary search for possible recent or present-day, methane-emission zones in the regions over which enrichments of atmospheric methane have been reported.

An aeolian system located in Aonia Terra (eastern Thaumasia region) consists of six dark dune fields. The dune pattern suggests an organized extended sand transport system, which is characterized by the presence of long sand corridors. The latter connects the different ergs with potential sources. The sand stored in the ergs is provided by layered materials exposed in pits and crater walls and by the ergs themselves. Most of the sand converges from the marginal dune fields into the central erg C. The latter develops in an area of convergence of at least three different winds: from the southwest, the northeast and the northwest. The northwesterly flows seem to postdate the other winds as suggested by the development of a complex dune pattern in the western portion of the erg C, representing a successive episode of aeolian construction. Collectively such complex dune patterns show how dune fields could record major changes in the wind regimes of Mars.

A variety of sedimentary deposits is observed in Xanthe Terra, Mars, including Gilbert-type deltas, fan deltas dominated by resedimentation processes, and alluvial fans. Sediments were provided through deeply incised valleys, which were probably incised by both runoff and groundwater sapping. Mass balances based on High-Resolution Stereo Camera (HRSC) digital terrain models show that up to ∼30% of the material that was eroded in the valleys is present as deltas or alluvial fan deposits. Stratigraphic relationships and crater counts indicate an age of ∼4.0 to ∼3.8 Ga for the fluvial activity. Hydrologic modeling indicates that the deposits were probably formed in geologically very short time scales. Our results point to episodes of a warmer and wetter climate on early Mars, followed by a long period of significantly reduced erosion rates.

Cassini radar images show a variety of fluvial channels on Titan's surface, often several hundreds of kilometers in length. Some (predominantly at low- and mid-latitude) are radar-bright and braided, resembling desert washes where fines have been removed by energetic surface liquid flow, presumably from methane rainstorms. Others (predominantly at high latitudes) are radar-dark and meandering and drain into or connect polar lakes, suggesting slower-moving flow depositing fine-grained sediments. A third type, seen predominantly at mid- and high latitudes, have radar brightness patterns indicating topographic incision, with valley widths of up to 3 km across and depth of several hundred meters. These observations show that fluvial activity occurs at least occasionally at all latitudes, not only at the Huygens landing site, and can produce channels much larger in scale than those observed there. The areas in which channels are prominent so far amount to about 1% of Titan's surface, of which only a fraction is actually occupied by channels. The corresponding global sediment volume inferred is not enough to account for the extensive sand seas. Channels observed so far have a consistent large-scale flow pattern, tending to flow polewards and eastwards.

The paradigm of an ancient warm, wet, and dynamically active Mars, which transitioned into a cold, dry, and internally dead planet, has persisted up until recently despite published Viking-based geologic maps that indicate geologic and hydrologic activity extending into the Late Amazonian epoch. This paradigm is shifting to a water-enriched planet, which may still exhibit internal activity, based on a collection of geologic, hydrologic, topographic, chemical, and elemental evidences obtained by the Viking, Mars Global Surveyor (MGS), Mars Odyssey (MO), Mars Exploration Rovers (MER), and Mars Express (MEx) missions. The evidence includes: (1) stratigraphically young rock materials such as pristine lava flows with few, if any, superposed impact craters; (2) tectonic features that cut stratigraphically young materials; (3) features with possible aqueous origin such as structurally controlled channels that dissect stratigraphically young materials and anastomosing-patterned slope streaks on hillslopes; (4) spatially varying elemental abundances for such elements as hydrogen (H) and chlorine (Cl) recorded in rock materials up to 0.33 m depth; and (5) regions of elevated atmospheric methane. This evidence is pronounced in parts of Tharsis, Elysium, and the region that straddles the two volcanic provinces, collectively referred to here as the Tharsis/Elysium corridor. Based in part on field investigations of Solfatara Crater, Italy, recommended as a suitable terrestrial analog, the Tharsis/Elysium corridor should be considered a prime target for Mars Reconnaissance Orbiter (MRO) investigations and future science-driven exploration to investigate whether Mars is internally and hydrologically active at the present time, and whether the persistence of this activity has resulted in biologic activity.

Veins cutting across the Devonian conical mounds of the Hamar Laghdad Ridge (eastern Anti-Atlas, Morocco) were the carriers of geofluids. Although not completely determined, the composition of these fluids seems related to hydrothermal and seepage fluxes that were the primary contributors to the establishment of sub-seafloor (cryptic) environments linking deeper fluid sources to the seafloor. The optical and scanning electron microscope investigation of the laminated carbonate infill of these veins has revealed that they consist of stromatolite- and oncolite-like fabrics. In the Early and Middle Devonian mounds, the laminated carbonates contain morphologies that are attributable to microbially mediated processes that in turn suggest a direct biological contribution to the deposition of the veins infill. Microbial evidence include rod-shaped and cocci clusters embedded in amorphous membranes, iron-rich filaments organized as mat-like and biodictyon filamentous aggregates, or isolated filaments, microbial clotted textures and peloids. Moreover, the oncoids from the veins of the Middle Devonian (Hollard) mound have been interpreted as the mineral replacement of crypto-microorganisms as Frutexites . Other microbial evidence are biominerals and include carbonate with spheroids and pyrite framboids, in which typifying hydrocarbon seep environments. The Hollard Mound, which is the only one with a well-documented origin by hydrocarbon seepage, shares a number of geomicrobiological evidence with other Early Devonian mounds. These evidence, which are supplemented by δ 13 C-depleted data, suggest that the infill of the veins system in the Hamar Laghdad mounds would be the product of chemotrophic/chemosynthetic microbial communities that are adapted to crypto-habitats sustained by hydrocarbon (and other components) fluid fluxes.

The basaltic Azas Plateau volcanic field is located in the Tuva Republic of the Russian Federation. The area was glaciated multiple times, and the field is characterized by the formation of subglacial volcanoes called tuyas, but subaerial volcanoes and lava fields also exist. A combined study of remote sensing and field observations in the vicinity of the tuyas in the southeastern Azas Plateau volcanic field identified landforms that are best explained by the jokulhlaup hypothesis. The landforms include elongated hills, paleochannels, and butte and basin topography. These landforms are hypothesized to have formed by both erosion and deposition caused by high-energy water streams. The triggering for the hypothesized jokulhlaups was either melting of ice by subglacial volcanism and/or destabilization of ice-dammed/subglacial reservoirs. The age estimation of the flood events is difficult, but they probably occurred during the ice ages of the Quaternary, as late as in the Middle-Late Pleistocene.

International audience; The Cassini Titan Radar Mapper obtained Synthetic Aperture Radar images of Titan's surface during four fly-bys during the mission's first year. These images show that Titan's surface is very complex geologically, showing evidence of major planetary geologic processes, including cryovolcanism. This paper discusses the variety of cryovolcanic features identified from SAR images, their possible origin, and their geologic context. The features which we identify as cryovolcanic in origin include a large (180 km diameter) volcanic construct (dome or shield), several extensive flows, and three calderas which appear to be the source of flows. The composition of the cryomagma on Titan is still unknown, but constraints on rheological properties can be estimated using flow thickness. Rheological properties of one flow were estimated and appear inconsistent with ammonia-water slurries, and possibly more consistent with ammonia-water-methanol slurries. The extent of cryovolcanism on Titan is still not known, as only a small fraction of the surface has been imaged at sufficient resolution. Energetic considerations suggest that cryovolcanism may have been a dominant process in the resurfacing of Titan.

Gully morphology (often summarized as comprising an alcove, channel and debris apron) is one of the key elements used to support the argument for liquid water in the recent past on Mars. Nevertheless, the processes that create different gully morphologies, on both Mars and Earth, are not fully understood. One of the puzzling morphologic attributes of Martian dune gullies is their apparent lack of an apron, or terminal deposit, which has caused debate about their formation process. Several physical processes such as runoff, debris flows, granular flows, and sliding blocks falling downslope could explain the formation of these gullies. In this work, we focus on the role of liquid in the substrate as well as in the flow and choose to experimentally test the plausibility of this hypothesis. We performed a series of analogue experiments to investigate the formation of gullies on sand dune-like substrates. We used controlled flows of water over an inclined sand-box to produce gully-like forms. Ice-rich sedimentary substrates were used, including substrates that included a thin liquid water-saturated thawed layer (an ‘active layer’) above the ice-saturated zone to give an analogue for a ‘periglacial’ environment. We quantitatively demonstrate that debris flow processes in ‘periglacial’ experiments are conducive to the formation of narrow and long channels with small terminal deposits with perched channels. By re-analysis of Martian elevation data for dune-gullies on Mars, we have found good evidence that such terminal deposits could exist. Our experiments revealed that increased water content in the thawed layer above the frozen bed increases flow-length due to the subsequent reduction in infiltration capacity. Water is incorporated into the flow by erosion of the wet thawed layer (sand plus water) and by drainage of the thawed layer. Using a Mars environment simulation chamber, we found that atmospheric pressure conditions seem to have a limited influence on the morphology of the flows. Our experimental investigation allowed the reproduction of terrestrial debris flow and Martian gully morphologies, suggesting that a substrate that is resistant to infiltration could be present beneath the dune gullies on Mars. We suggest that, like in our laboratory experiments, the presence of ice at shallow depth is a possible explanation for the formation of these morphologies and that a wet thawed layer is a possible explanation for the long flow-length.

This study investigates the geomicrobiological potential of Upper Pleistocene evaporite deposits of the Chott el Gharsa, a wide continental sabkha in southern Tunisia. Organic and inorganic-derived biosignatures are mostly contained in microcrystalline, laminated gypsum lithofacies consisting of light/dark alternations of concordant laminae, which have precipitated from high salt concentrated waters. These biosignatures include mineralized microbial-interpreted morphologies, such as mucilage, rods, and microfibers, and dumbbell morphologies in the hollow cores of dolomite crystals that are associated with sulfates. Mineral products that are induced by microbial activity and their organic compounds lead to the formation of lenticular-shaped gypsum crystals, with a high length/width ratio, dolomite precipitation and formation of pyrite framboids. Morphological and structural aspects of these biosignatures, and their composition, in laminated, dolomite-rich sulfate deposits could be detected through microscopic investigations and micro-analyses performed by the instrumentation that is planned for ongoing Mars sample return missions.

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

The platinum metals depleted in the earth's crust are relative to their cosmic abundance; concentration of these elements in sediments may thus indicate influxes of extraterrestrial material. Analysis of these parameters are done easily by Neutron Activation Analysis (NAA) and comparative results with ICP-MS technique show a good match. Results, adjust parameters and limits of this method will be displayed in tables.