Habitability-Mars-Salts-Water activity-Life in extreme environments. Astrobiology 16, 427-442.

Hydrothermal environments driven by volcanism are prime astrobiological targets on Mars, due to their ability to support and preserve microbial ecosystems. Volcano -ice interactions on On Earth, volcano -ice interactions produce many hydrothermal habitats available to microbial colonisation, and thus provide an analogue to past environments on Mars, where many landforms have been attributed to volcano -cryospheric interaction. However, Mars exploration urgently requires a framework for identifying such environments on a range of scales and with a range of geological criteria. In this paper rRemote sensing data were combined with sub-mm environmental mapping and sample analysis that included (X-ray diffraction, Raman spectroscopy, thin section petrography, scanning electron microscopy, electron dispersive spectrometer analysis, and dissolved ion water chemistry,) to characterise samples from two areas of basaltic volcano -ice interaction: namely Askja and Kverkfjöll volcanoes in Iceland. Askja was erupted subglacially during the Pleistocene, and is now exposed within a volcanic desert. Kverkfjöll is a subglacial volcano beneath on the northern margin of Vatnajökull ice cap, and hosts active hydrothermal systems. NE-trending fissure swarm ridges extend between these two volcanic systems. Multiple Holocene glacial outburst (jökulhlaup) sedimentary deposits lie to the north of Kverkfjöll. Hydrothermal environments at Kverkfjöll were found to be predominantly acidic, with dissolved sulphate dominating the water chemistry. These hydrothermal environments vary across a small (<100 m) spatial scale, and include hot springs, anoxic pools, meltwater lakes, and sulphur-and iron-depositing fumaroles. Biomats, two in association with individual goethite and pyrite mineral terraces, were common at Kverkfjöll. In-situ and laboratory VNIR (440 -1000 nm) reflectance spectra representative of Mars rover multispectral imaging show spectral profiles to be influenced by Fe 2+/3+ -bearing minerals. Overall, sediments and lavas display two types of hydrothermal alteration: a low-temperature (<120°C) assemblage dominated by palagonite, sulfates, and iron oxides; and a high-temperature (>120°C) assemblage signified by heulandite and quartz. This Overall, this work provides a framework for identifying such environments during future exploration of Mars, given their high astrobiological potential, and Claire Cousins -BBK 14/08/12 3 provides a descriptive reference for the two prominent active hydrothermal environments at Kverkfjöllwhich can be used as analogues for those on Mars.

The scientific objectives of the ExoMars rover are designed to answer several key questions in the search for life on Mars. In particular, the unique subsurface drill will address some of these, such as the possible existence and stability of subsurface organics. PanCam will establish the surface geological and morphological context for the mission, working in collaboration with other context instruments. Here, we describe the PanCam scientific objectives in geology, atmospheric science, and 3-D vision. We discuss the design of PanCam, which includes a stereo pair of Wide Angle Cameras (WACs), each of which has an 11-position filter wheel and a High Resolution Camera (HRC) for high-resolution investigations of rock texture at a distance. The cameras and electronics are housed in an optical bench that provides the mechanical interface to the rover mast and a planetary protection barrier. The electronic interface is via the PanCam Interface Unit (PIU), and power conditioning is via a DC-DC converter. PanCam also includes a calibration target mounted on the rover deck for radiometric calibration, fiducial markers for geometric calibration, and a rover inspection mirror. Key Words: Mars—ExoMars—Instrumentation—Geology—Atmosphere—Exobiology—Context. Astrobiology 17, 511–541.

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11Volcano-ice interaction has been a widespread geologic process on Earth that 12 continues to occur to the present day. The interaction between volcanic activity 13 and ice can generate substantial quantities of liquid water, together with steep 14 thermal and geochemical gradients typical of hydrothermal systems. 15Environments available for microbial colonization within glaciovolcanic systems 16 are wide-ranging and include the basaltic lava edifice, subglacial caldera 17 meltwater lakes, glacier caves, and subsurface hydrothermal systems. There is 18 widespread evidence of putative volcano -ice interaction on Mars throughout its 19 history and at a range of latitudes. Therefore, it is possible that life on Mars may 20 have exploited these habitats, much in the same way as has been observed on 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 hydrothermal mineral deposits, basaltic lava flows, and subglacial lacustrine 25 deposits. Here, we briefly review the evidence for volcano-ice interactions on 26Mars and discuss the geomicrobiology of volcano-ice habitats on Earth. In 27 addition, we explore the potential for the detection of these environments on Mars 28and any biosignatures these deposits may contain. 29 30 Introduction 31The detection of extraterrestrial life has become a major goal in modern space 32 exploration, with Mars in particular being recognized as an appropriate target. The 33 search for life on Mars during the past few decades has been significantly aided 34 by research into life within martian analogue environments on Earth (e.g., 35Cavicchioli 2002). Environments that have received considerable attention as 36 proxies for past or present martian habitats include the Antarctic Dry Valleys 37 (Wierzchos et al., 2005;Walker & Pace 2007), the Atacama Desert (Navarro-38 Gonzalez et al., 2003), evaporite environments (Rothschild 1990; Edwards et al., 39 2006), and permafrost (Gilichinsky et al., 2007). These environments have shown 40 an array of resilient microbial communities that thrive under harsh environmental 41 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 The martian crust is predominantly igneous in nature and ranges from basaltic to 45 andesitic in composition (McSween et al., 2009). Therefore, it is imperative to 46 understand martian volcanic environments in terms of their habitability and 47 potential for microbial colonisation. In particular, where volcanism interacts with 48 liquid water, there is the potential to support life, as seen on Earth (e.g., Boston et 49 al., 1992). Liquid water is unstable at the martian surface today and has been for a 50 considerable part of its history. Water currently exists a...