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

Executive summary provided in lieu of abstract., SCOPUS: no.j, info:eu-repo/semantics/published

Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re-evaluate and update the sample-related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub-objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub-Objectives for MSR Identified by iMOST: Objective 1 Interpret the primary geologic processes and history that formed the Martian geologic record, with an emphasis on the role of water. Intent To investigate the geologic environment(s) represented at the Mars 2020 landing site, provide definitive geologic context for collected samples, and detail any characteristics that might relate to past biologic processesThis objective is divided into five sub-objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. Intent To understand the preserved Martian sedimentary record. Samples A suite of sedimentary rocks that span the range of variation. Importance Basic inputs into the history of water, climate change, and the possibility of life 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. Intent To evaluate at least one potentially life-bearing “habitable” environment Samples A suite of rocks formed and/or altered by hydrothermal fluids. Importance Identification of a potentially habitable geochemical environment with high preservation potential. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. Intent To evaluate definitively the role of water in the subsurface. Samples Suites of rocks/veins representing water/rock interaction in the subsurface. Importance May constitute the longest-lived habitable environments and a key to the hydrologic cycle. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. Intent To constrain time-variable factors necessary to preserve records of microbial life. Samples Regolith, paleosols, and evaporites. Importance Subaerial near-surface processes could support and preserve microbial life. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. Intent To provide definitive characterization of igneous rocks on Mars. Samples Diverse suites of ancient igneous rocks. Importance Thermochemical record of the planet and nature of the interior. Objective 2 Assess and interpret the potential biological history of Mars, including assaying returned samples for the evidence of life. Intent To investigate the nature and extent of Martian habitability, the conditions and processes that supported or challenged life, how different environments might have influenced the preservation of biosignatures and created nonbiological “mimics,” and to look for biosignatures of past or present life.This objective has three sub-objectives: 2.1 Assess and characterize carbon, including possible organic and pre-biotic chemistry. Samples All samples collected as part of Objective 1. Importance Any biologic molecular scaffolding on Mars would likely be carbon-based. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. Samples All samples collected as part of Objective 1. Importance Provides the means of discovering ancient life. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Samples All samples collected as part of Objective 1. Importance Planetary protection, and arguably the most important scientific discovery possible. Objective 3 Quantitatively determine the evolutionary timeline of Mars. Intent To provide a radioisotope-based time scale for major events, including magmatic, tectonic, fluvial, and impact events, and the formation of major sedimentary deposits and geomorphological features. Samples Ancient igneous rocks that bound critical stratigraphic intervals or correlate with crater-dated surfaces. Importance Quantification of Martian geologic history. Objective 4 Constrain the inventory of Martian volatiles as a function of geologic time and determine the ways in which these volatiles have interacted with Mars as a geologic system. Intent To recognize and quantify the major roles that volatiles (in the atmosphere and in the hydrosphere) play in Martian geologic and possibly biologic evolution. Samples Current atmospheric gas, ancient atmospheric gas trapped in older rocks, and minerals that equilibrated with the ancient atmosphere. Importance Key to understanding climate and environmental evolution. Objective 5 Reconstruct the processes that have affected the origin and modification of the interior, including the crust, mantle, core and the evolution of the Martian dynamo. Intent To quantify processes that have shaped the planet's crust and underlying structure, including planetary differentiation, core segregation and state of the magnetic dynamo, and cratering. Samples Igneous, potentially magnetized rocks (both igneous and sedimentary) and impact-generated samples. Importance Elucidate fundamental processes for comparative planetology. Objective 6 Understand and quantify the potential Martian environmental hazards to future human exploration and the terrestrial biosphere. Intent To define and mitigate an array of health risks related to the Martian environment associated with the potential future human exploration of Mars. Samples Fine-grained dust and regolith samples. Importance Key input to planetary protection planning and astronaut health. Objective 7 Evaluate the type and distribution of in-situ resources to support potential future Mars exploration. Intent To quantify the potential for obtaining Martian resources, including use of Martian materials as a source of water for human consumption, fuel production, building fabrication, and agriculture. Samples Regolith. Importance Production of simulants that will facilitate long-term human presence on Mars. Summary of iMOST Findings: Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M-2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity. Our ability to interpret the source geologic units and processes by studying sample sub sets is highly dependent on the quality of the sample context. In the case of the M-2020 samples, the context is expected to be excellent, and at multiple scales. (A) Regional and planetary context will be established by the on-going work of the multi-agency fleet of Mars orbiters. (B) Local context will be established at field area- to outcrop- to hand sample- to hand lens scale using the instruments carried by M-2020. A significant fraction of the value of the MSR sample collection would come from its organization into sample suites, which are small groupings of samples designed to represent key aspects of geologic or geochemical variation. If the Mars 2020 rover acquires a scientifically well-chosen set of samples, with sufficient geological diversity, and if those samples were returned to Earth, then major progress can be expected on all seven of the objectives proposed in this study, regardless of the final choice of landing site. The specifics of which parts of Objective 1 could be achieved would be different at each of the final three candidate landing sites, but some combination of critically important progress could be made at any of them. An aspect of the search for evidence of life is that we do not know in advance how evidence for Martian life would be preserved in the geologic record. In order for the returned samples to be most useful for both understanding geologic processes (Objective 1) and the search for life (Objective 2), the sample collection should contain BOTH typical and unusual samples from the rock units explored. This consideration should be incorporated into sample selection and the design of the suites. The retrieval missions of a MSR campaign should (1) minimize stray magnetic fields to which the samples would be exposed and carry a magnetic witness plate to record exposure, (2) collect and return atmospheric gas sample(s), and (3) collect additional dust and/or regolith sample mass if possible.

Executive Summary: Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re-evaluate and update the sample-related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub-objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned martian samples would impact future martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others.

Objective To describe the development, test-retest reliability, internal consistency, and convergent validity of the McKnight Risk Factor Survey-III (MRFS-III). The MRFS-III was designed to assess a number of potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls. Method Several versions of the MRFS were pilot tested before the MRFS-III was administered to a sample of 651 4th through 12th- grade girls to establish its psychometric properties. Results Most of the test-retest reliability coefficients of individual items on the MRFS-III were r >.40. Alpha coefficients for each risk and protective factor domain on the MRFS-III were also computed. The majority of these coefficients were r >.60. High convergent validity coefficients were obtained for specific items on the MRFS-III and measures of self-esteem (Rosenberg Self-Esteem Scale) and weight concerns (Weight Concerns Scale). Conclusions The test-retest reliability, internal consistency, and convergent validity of the MRFS-III suggest that it is a useful new instrument to assess potential risk and protective factors for the development of disordered eating in preadolescent and adolescent girls. © 1999 by John Wiley & Sons, Inc. Int J Eat Disord 25: 195–214, 1999.

International audience; At Titan's equatorial latitudes there are tens of thousands of dunes, a landform typical of desert environments where sand does not become anchored by vegetation or fluids. Model climate simulations predict generally dry conditions at the equator and humid conditions near the poles of Titan, where lakes of methane/ethane are found. However, moderate relative methane humidity was observed at the Huygens landing site, recent rainfall was seen by Cassini ISS near the Belet Sand Sea, and a putative transient lake in Shangri-La was observed by Cassini VIMS, all of which indicate abundant fluids may be present, at least periodically, at Titan's equatorial latitudes. Terrestrial observations and studies demonstrate dunes can exist and migrate in conditions of high humidity. Active dunes are found in humid climates, indicating the movement of sand is not always prohibited by the presence of fluids. Sand mobility is related to precipitation, evaporation and wind speed and direction. If dune surfaces become wetted by rainfall or rising subsurface fluids, they can become immobilized. However, winds can act to dry the uppermost layers, freeing sands for saltation and enabling dune migration in wet conditions. Active dunes are found in tropical NE Brazil and NE Australia, where there are alternating dry and wet periods, a condition possible for Titan's tropics. Rising and falling water levels lead to the alteration of dune forms, mainly from being anchored by vegetation, but also from cementation by carbonates or clays. Studies of Titan's dunes, which could undergo anchoring of organic sediments by hydrocarbon fluids, could inform the relative strength of vegetation vs. cementation at humid dune regions on Earth. Furthermore, a comprehensive survey of dune morphologies near regions deemed low by SARTopo and stereo, where liquids may collect in wet conditions, could reveal if bodies of liquid have recently existed at Titan's tropics.

International audience; From a theoretical point of view, pure liquid water is not likely to be found at the present time on the Martian surface because atmospheric pressure/temperature conditions are below the water triple-point. However, gullies discovered by Malin and Edgett (2000) suggest that significant amounts of liquid water have flowed on Mars in a recent past. Recent works showed that Martian dunes have exhibited modifications over the past years, including topographic changes on aprons and new channel incisions into dune surfaces (Diniega et al., 2010; Dundas et al., 2010; Reiss et al., 2010; Hansen et al., 2011). These seasonal activities can be explained by CO 2 frost processes (Diniega et al., 2010; Dundas et al., 2010; Hansen et al., 2011) or melting of water frost and/or near surface ice triggering sand-water flows (Reiss et al., 2010). The new possibility given by HiRISE images to perform precise monitoring of present modifications of the surface of Mars allows to improve our understanding of the seasonal activity and of the topographic evolution of dunes. Numerous changes could be observed during the last three Martian years. Here, we show that there is a perennial activity on the Martian dune Russell: surface flows appear seasonally (Reiss et al., 2010), after the total disappearance of CO 2 at spring (Gardin et al., 2010; Reiss et al., 2010), and are able to erode their substrate. This perennial activity is constituted by a complex interconnected rill system that is recorded all year long and which grows from one year to the next at a rate of 10000 m2.yr-1. These flows are viscous and able to erode as well to transport a non negligible quantity of sand with a grain size of 500±100 [U+F06D]m at a minimum velocity of ∼1.4.10-4m.s-1. These flows could be composed in part of liquid water. The origin of the liquid water is probably from the melting of the water ice (accumulated on the dune surface by vapour condensation during winter) at spring or/and from the defrosting of a small active layer of permafrost. There are at least four processes that could explain the physical properties of this perennial activity: (1) brine flow (Chevrier et al., 2008), (2) liquid water flow mixed with sand (Reiss et al., 2010), (3) liquid water flow mixed with snow or ice, (4) a combination of the previous three processes.

International audience; Introduction: A large morphological diversity of gullies is observed on Earth and on Mars. Debris flow – a non-newtonian flow comprising a sediment-water mix – is a common process attributed to gully formation on both planets [1, 2]. Many variables can influence the morphology of debris flows (grainsizes, discharge , slope, soil moisture, etc) and their respective influences are difficult to disentangle in the field. Furthermore effects specific to the martian environment have not yet been explored in detail. Some preliminary laboratory simulations have already been performed that isolate some of these variables. Cold room experiments [3] were already perfomed to test the effect of a melted surface layer on the formation of linear gullies over sand dunes. Low pressure experiments [4] were performed to test the effect of the atmospheric pressure on erosional capacity and runout distance of the flows. Our aim is to develop a new set of experiments both under Martian atmospheric pressure and terrestrial atmospheric pressure in order to reproduce the variability of the observed morphologies under well constrained experimental conditions.

The entry, descent and landing of ExoMars offer a rare (once-per-mission) opportunity to perform in situ investigation of the martian environment over a wide altitude range. Entry, Descent and Landing System (EDLS) measurements can provide essential data for atmospheric scientific investigations.\ud \ud We intend to perform atmospheric science measurements by exploiting data from EDLS engineering sensors and exploiting their readings beyond the expected engineering information.

International audience; Introduction : Liquid water is not likely to be found on the surface of Mars because of atmospheric pres-sure/temperature conditions below water's triple-point. However, the discovery of gullies suggests that significant amounts of liquid water has flowed on Mars in a recent past [1]. This study focus on morphology of gullies over dunes on the Russell crater (54.5°S ; 12.7°E). Recent numerical simulations have shown that sinuous shapes of these Martian gullies over dunes can be better reproduced with liquid-water-bearing flows [2]. The discovery of debris flows on sand dunes is unexpexted and the origin of the fluid necessary for the formation of debris flows remains currently a mystery. Recent work shows that the gullies located on the Russell dune are not only extremely youthfull but seem also to be still active [3]. This study aims to : 1/ realize a morphological description of the debris flows of the Russell dune and the Present flow activity using the HiRISE images ; 2/ estimates the physical properties of the flows (velocities, flow rates) and the maximum grain size of the dune surface material ; 3/ use the different flow morphologies and the calculated parameters to compare the debris flows and the Present flow activity.

Planetary Decadal Survey 2013-2022: The Future of Planetary Science, Nasa - Report, http://sse.jpl.nasa.gov/2013decadal/index.cfm

International audience; A study sponsored by MEPAG has defined the possibilities for cooperative science using two rovers under consideration for launch to Mars in 2018 (ESA’s ExoMars, and a NASA-sourced rover concept for which we use the working name of MAX-C). The group considered collaborative science opportunities both without change to either proposed rover, as well as with some change allowed. Planning focused on analysis of shared and separate objectives, with concurrence on two high priority shared objectives that could form the basis of highly significant collaborative exploration activity. The first shared objective relates to sending the proposed rovers to a site interpreted to contain evidence of past environments with high habitability potential, and with high preservation potential for physical and chemical biosignatures where they would evaluate paleoenvironmental conditions, assess the potential for preservation of biotic and/or prebiotic signatures, and search for possible evidence of past life and prebiotic chemistry. The second shared objective relates to the collection, documentation, and suitable packaging of a set of samples by the rovers that would be sufficient to achieve the scientific objectives of a possible future sample return mission. Achieving cooperative science with the two proposed rovers implies certain compromises that might include less time available for pursuing each rover’s independent objectives, implementation of some hardware modifications, and the need to share a landing site that may not be optimized for either rover. Sharing a landing site has multiple implications, including accepting a common latitude restriction, accepting the geological attributes of the common landing site, and creation of a potential telecommunications bottleneck. Moreover, ensuring a safe landing with the sky crane and pallet system envisioned for the mission would likely result in landing terrain engineering requirements more constraining than those for MSL. Additional possible constraints on the distances the rovers could traverse suggest primary science targets should be within the landing ellipse. Hence, hazard avoidance capability might be necessary to allow for consideration of scientifically compelling sites with a mixture of safe and unsafe terrain.

International audience; Recent work has shown that gullies are among the most youthful features on Mars [1] and have been taken as evidence for significant amounts of liquid water in the recent past. Recent studies show that the gullies located on the Russell Crater dune are not only extremely youthful but also appear to be still active [2]. Here we report of a polygenic evolution of debris flow dunes with two phases: 1/ debris flows on hill slopes in recent Martian times (less than 10 My) could be formed by (i) runoff and debris flows with liquid water from groundwater aquifers [1]; [3], (ii) snow-melt ([4]; [5], (iii) various CO 2-driven mechanisms ([6]; [7]; [8]) or (iv) melting of near-surface ground ice (< 1m meter) at high obliquity [9]; 2/ defrosting activity at present time with formation of relatively small sinuous hand branching channels.

International audience

International audience

Guide book of a field trip in the southern Tunisian chotts