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No magnetotrophic organism on Earth is known to use magnetic fields as an energy source or the storage of information. However, a broad diversity of life forms is sensitive to magnetic fields and employs them for orientation and navigation, among other purposes. If the magnetic field strength were much larger, such as that on planets around neutron stars or magnetars, metabolic energy could be obtained from these magnetic fields in principle. Here, we introduce three hypothetical models of magnetotrophic organisms that obtain energy via the Lorentz force. Even if an organism uses magnetic fields only as an energy source, but otherwise is relying on biochemistry, this organism would be by definition a magnetotrophic form of life as we do not know it.

Motility is a great biosignature and its pattern is characteristic for specific microbes. However, motion does also occur within the cell by the myriads of ongoing processes within the cell and the exchange of gases and nutrients with the outside environment. Here, we propose that the sum of these processes in a microbial cell is equivalent to a pulse in complex organisms and suggest a first approach to measure the “living pulse” in microorganisms. We emphasize that if a “living pulse” can be shown to exist, it would have far-reaching applications, such as for finding life in extreme environments on Earth and in extraterrestrial locations, as well as making sure that life is not present where it should not be, such as during medical procedures and in the food processing industry.

There are two types of rogue planets, sub-brown dwarfs and “rocky” rogue planets. Sub-brown dwarfs are unlikely to be habitable or even host life, but rocky rogue planets may have a liquid ocean under a thick atmosphere or an ice layer. If they are overlain by an insulating ice layer, they are also referred to as Steppenwolf planets. However, given the poor detectability of rocky rogue planets, there is still no direct evidence of the presence of water or ice on them. Here we discuss the possibility that these types of rogue planets could harbor unicellular organisms, conceivably based on a variety of different energy sources, including chemical, osmotic, thermal, and luminous energy. Further, given the theoretically predicted high number of rogue planets in the galaxy, we speculate that rogue planets could serve as a source for galactic panspermia, transferring life to other planetary systems This work was supported by the Project “MarsFirstWater”, European Research Council Consolidator Grant no 818602. Peerreview

BIOLEX is a concept designed for in situ science on the Moon or in its orbit. As heritage of the polar and space experiment BIOMEX (Biology and Mars Experiment) on the ISS it is a more developed concept. Measurement operations on an exposure platform as well as within a micro-greenhouse device are part of this concept. The goal is to investigate the use of lunar resources as well as to analyse the stability of biomolecules as potential biosignatures serving as reference for future space exploration missions to Mars and the icy ocean moons in the outer solar system. Astrobiological exploration of the solar system is a priority research area such as emphasized by the European Astrobiology Roadmap (AstRoMap). It is focusing on several research topics, such as "Habitability" and on "Biomarkers for the detection of life". Therefore, "space platforms and laboratories", such as the EXPOSE setup installed outside the ISS, are essential to gain more knowledge on space- and planetary environments, which might be an essential basis for improvement of the robotic and human interplanetary exploration (Moon, Mars, Encedalus, Titan and Europa). In reference to these exposure platforms a new generation of hardware is needed to be installed in the lunar orbit or directly on the Moon. The BIOLEX is representing by its LOGOS (Lunar Organisms, Geo-microbiology and Organics Space Experiment) cubes such a concept combining the life detection topics with topics relevant to autonomous life supporting systems. A combination of a sample exposure device and a microhabitat for plants and microorganisms could address a tremendous number of questions from astrobiology and life sciences. The main scientific objectives for the use of BIOLEX-LOGOS cubes are: (i) in situ measurements by spectroscopy methods (such as Raman, IR, UV/VISspectroscopy) for analysis of biosignatures and their stability what is relevant for support of future life detection missions on Mars and the icy moons in the outer solar system); (ii) in situ measurements of environmental conditions (radiation, pressure/vacuum, temperature, pH, humidity) in micro-modules or compartments in reference to planned micro-habitat experiments placed on the Moon or incorporated on an exposure facility in orbit; (iii) in situ measurements of microorganisms’ activity in micro-modules / compartments in reference to planned microhabitat experiments placed on the moon or incorporated in the exposure facility in orbit. In reference to these scientific ideas the Moon is an excellent platform to operate different space experiments which will be of relevance for astrobiology, life sciences and human space missions. BIOLEX tries to fulfil a large number of scientific investigations in reference to these disciplines. The lunar environment is much harsher compared to Mars; and tests on biomolecules in this environment could provide information on their stability and therefore on the value to be used as reference for future space missions to Mars or the icy ocean moons in the outer solar system. Resources of the Moon such as the regolith or the freely available radiation on the surface could be tested by using them in a micro-greenhouse. Within this greenhouse different filters could test the optimal spectra range of the radiation.

The next two rover missions to Mars, ESA/Roscosmos’s ExoMars2020 and NASA’s Mars2020, will carry for the first time Raman spectrometers potentially able to dectect traces of past or present life. To support and interpret future spectroscopic data correctly a better understanding of potential habitable environments and putative biosignatures, using analogue environments such as the Atacama Desert, is of paramount importance. In the Atacama Desert, one of the driest places on Earth, life has developed adaptive strategies to decreasing amounts of water: from refuges inside or below rocks as endoliths or hypoliths to inside salts in hygroscopic niches (Davila & Schulze-Makuch, 2016). In the hyperarid core one of the last refuges for life are inside salt crusts using deliquescence as a water source or being in the subsurface waiting for transitory episodes of increased moisture (Schulze-Makuch et al., 2018). These adaptive strategies might also apply to putative Martian life which endured a transition from a water rich past to the very harsh surface conditions of the present giving us clues on where to best look for traces of life on the Red Planet. Salt crusts and salt nodules are particularly interesting targets in this regard because they reside on or very near the surface and are thus easily accessible to future robotic missions. In the Atacama, salt nodules have been shown to host photosynthetic organisms containing easily identifiable pigments by Raman spectroscopy such as carotenoids and scytonemin (Vítek et al., 2014). One of the most damaging factors for life and its remains, both in the Atacama and on Mars, is solar radiation. To investigate the spatial distribution of potential Raman signatures in micro-niches we generated georeferenced 3D-reconstructions of the sampling areas using photogrammetry techniques and plotted the dose received according to the nodules’ orientation. We then analysed salt nodule along dry cut north-south thick sections using Raman mapping to infer any relations between the amount of light received and the presence of detectable signal. Preliminary data show an increased presence of carotenoids, scytonemin, and other biomolecules signals on the nodules oriented towards the south, which are the-more-protected sections of the nodules. References Davila, A.F. & Schulze-Makuch, D. (2016) The Last Possible Outposts for Life on Mars. Astrobiology 16:159–168. Schulze-Makuch, D., Wagner, D., Kounaves, S.P., Mangelsdorf, K., Devine, K.G., Vera, J.-P. de, Schmitt-Kopplin, P., Grossart, H.-P., Parro, V., Kaupenjohann, M., Galy, A., Schneider, B., Airo, A., Frösler, J., Davila, A.F., Arens, F.L., Cáceres, L., Cornejo, F.S., Carrizo, D., Dartnell, L., DiRuggiero, J., Flury, M., Ganzert, L., Gessner, M.O., Grathwohl, P., Guan, L., Heinz, J., Hess, M., Keppler, F., Maus, D., McKay, C.P., Meckenstock, R.U., Montgomery, W., Oberlin, E.A., Probst, A.J., Sáenz, J.S., Sattler, T., Schirmack, J., Sephton, M.A., Schloter, M., Uhl, J., Valenzuela, B., Vestergaard, G., Wörmer, L. & Zamorano, P. (2018) Transitory microbial habitat in the hyperarid Atacama Desert. PNAS 115:2670–2675. Vítek, P., Jehlička, J., Ascaso, C., Mašek, V., Gómez-Silva, B., Olivares, H. & Wierzchos, J. (2014) Distribution of scytonemin in endolithic microbial communities from halite crusts in the hyperarid zone of the Atacama Desert, Chile. FEMS Microbiology Ecology 90:351–366.

The International Continental Scientific Drilling Program (ICDP) has long espoused studies of deep subsurface life, and has targeted fundamental questions regarding subsurface life, including the following: "(1) What is the extent and diversity of deep microbial life and what are the factors limiting it? (2) What are the types of metabolism/carbon/energy sources and the rates of subsurface activity? (3) How is deep microbial life adapted to subsurface conditions? (4) How do subsurface microbial communities affect energy resources? And (5) how does the deep biosphere interact with the geosphere and atmosphere?" (Horsfield et al., 2014) Many ICDP-sponsored drilling projects have included a deep-life component; however, to date, not one project has been driven by deep-life goals, in part because geomicrobiologists have been slow to initiate deep biosphere-driven ICDP projects. Therefore, the Deep Carbon Observatory (DCO) recently partnered with the ICDP to sponsor a workshop with the specific aim of gathering potential proponents for deep-life-driven ICDP projects and ideas for candidate drilling sites. Twenty-two participants from nine countries proposed projects and sites that included compressional and extensional tectonic environments, evaporites, hydrocarbon-rich shales, flood basalts, Precambrian shield rocks, subglacial and subpermafrost environments, active volcanotectonic systems, megafan deltas, and serpentinizing ultramafic environments. The criteria and requirements for successful ICDP applications were presented. Deep-life-specific technical requirements were discussed and it was concluded that, while these procedures require adequate planning, they are entirely compatible with the sampling needs of other disciplines. As a result of this workshop, one drilling workshop proposal on the Basin and Range Physiographic Province (BRPP) has been submitted to the ICDP, and several other drilling project proponents plan to submit proposals for ICDP-sponsored drilling workshops in 2016. (VLID)1731059

This article provides first insights into some of the fascinating aspects of astrobiology. The central focus of this research theme is directed towards questions which have interested humans for millennia: How has life developed? Where do we come from? Are we alone in the Universe? In order to approach these questions, astrobiology brings together a variety of disciplines such as astronomy, astrophysics, biology, biochemistry, chemistry, geology, mineralogy, and cosmology. In particular, scientists are more and more interested into the biological aspects and the interactions of (micro)-organisms with their geological environment. This interest is further fueled by numerous NASA and ESA missions to Mars that have spawned new insights into Mars as a potential habitat for life. Earth analog environments, which are characterized by conditions that occur in other parts of our solar system in even more extreme forms play an important role for astrobiological research. Examples include habitats that are characterized by extreme dryness and/or coldness such as the Atacama Desert in Chile, liquid asphalt lakes in Trinidad or the permafrost areas in Siberia. Extremophilic microorganisms such as cyanobacteria and methanogenic archaea or higher organisms such as lichens and bryophytes are used as model organisms to study the limits of life under simulated extreme conditions. In recent years, an active research network has been established in the Berlin-Brandenburg region that carried out joint astrobiology and habitability studies and which among other projects is currently conducting an ESA experiment onboard the International Space Station ISS.

BIOMEX (Biology and Mars Experiment) is a space experiment on the exposure platform EXPOSER2 launched by the Progress 56 mission on 24 July and placed on the outer side of the Russian Zvezda Module of the International Space Station (ISS). Twenty-five international institutes are working together and sharing different methods, planetary simulation facilities, and logistics to obtain information about the vitality of the tested microorganisms and the stability of biomolecules as possible biosignatures. This experiment comprises three investigational steps from the field to space: (i) field work with sample collection and habitat characterization at field sites with or without Mars analogy, (ii) Mars simulation experiments in the lab and (iii) exposure to real space conditions. For the second and third steps some of the microorganisms and bio-molecules are embedded in Marsanalog regolith mixtures, placed in compartments enriched with Mars-like CO 2 -atmosphere and exposed to solar irradiation levels approaching those affecting the surface of Mars to test habitability on Mars, as well as the ability to detect the selected, Mars-exposed bio-molecules. One of the aims of this experiment is to investigate the specific bio-related spectra of resistant molecules obtained by fluorescence analysis, Raman-spectroscopy, IR- and UV/VIS spectrometry before and after simulated and real space exposure. The obtained database of stable bio-molecules will support future exploration missions to Mars whose main goal is the search for life.

International audience; Looking for habitable conditions in the outer solar system our research focuses on the natural satellites rather than the planets themselves. Indeed, the habitable zone as traditionally defined may be larger than originally con-ceived. The strong gravitational pull caused by the giant planets may produce enough energy to sufficiently heat the interiors of orbiting icy moons. The outer solar system satellites then provide a conceptual basis within which new theories for understanding habitability can be constructed. Measurements from the ground but also by the Voyager, Galileo and the Cassini spacecrafts revealed the potential of these satellites in this context, and our understanding of habitability in the solar system and beyond can be greatly enhanced by investigating several of these bodies together [1]. Their environments seem to satisfy many of the "classical" criteria for habitability (liquid water, energy sources to sustain metabolism and chemical compounds that can be used as nutrients over a period of time long enough to allow the development of life). Indeed, several of the moons show promising conditions for habitability and the de-velopment and/or maintenance of life. Europa, Callisto and Ganymede may be hiding, under their icy crust, putative undersurface liquid water oceans [3] which, in the case of Europa [2], may be in direct contact with a silicate mantle floor and kept warm by tidally generated heat [4]. Titan and Enceladus, Saturn's satellites, were found by the Cassini-Huygens mission to possess active organic chemistries with seasonal variations, unique geological features and possibly internal liquid water oceans. Titan's rigid crust and the probable existence of a subsurface ocean create an analogy with terrestrial-type plate tectonics, at least surficial [5], while Enceladus' plumes find an analogue in gey-sers. As revealed by Cassini the liquid hydrocarbon lakes [6] distributed mainly at polar latitudes on Titan are ideal isolated environments to look for biomarkers. Currently, for Titan and Enceladus, geophysical models try to explain the possible existence of an oceanic layer that decouples the mantle from the icy crust. If the silicate mantles of Eu-ropa and Ganymede and the liquid sources of Titan and Enceladus are geologically active as on Earth, giving rise to the equivalent of hydrothermal systems, the simultaneous presence of water, geodynamic interactions, chemical en-ergy sources and a diversity of key chemical elements may fulfill the basic conditions for habitability. Titan has been suggested to be a possible cryovolcanic world due to the presence of local complex volcanic-like geomorphol-ogy and the indications of surface albedo changes with time [7,8]. Such dynamic activity that would most probably include tidal heating, possible internal convection, and ice tectonics, is believed to be a pre-requisite of a habitable planetary body as it allows the recycling of minerals and potential nutrients and provides localized energy sources. In a recent study by Sohl et al. [2013], we have shown that tidal forces are a constant and significant source of inter-nal deformation on Titan and the interior liquid water ocean can be relatively warm for reasonable amounts of am-monia concentrations, thus completing the set of parameters needed for a truly habitable planetary body. Such habi-tability indications from bodies at distances of 10 AU, are essential discoveries brought to us by space exploration and which have recently revolutionized our perception of habitability in the solar system. In the solar system's neighborhood, such potential habitats can only be investigated with appropriate designed space missions, like JUICE-Laplace (JUpiter ICy moon Explorer) for Ganymede and Europa [9]. JUICE is an ESA mission to Jupiter and its icy moons, recently selected to launch in 2022. References: [1] Coustenis, A., Encrenaz, Th., in "Life Beyond Earth : the search for habitable worlds in the Universe", Cambridge Univ. Press, 2013. [2] Patterson, G.W., et al.: AGU P41F-09, 2011. [3] Grasset, O., et al.: Astrobiology 13, 991-1004, 2013. [4] Sohl, F., et al.: submitted. [5] Solomonidou, A., et al.: PSS 77, 104-117, 2013. [6] Stofan, E.R., et al.: Nature 445, 61-64, 2007. [7] Solomonidou, A., et al.: submitted (a). [8] Solomonidou, A., et al: submitted (b). [9] Grasset, O., et al.: PSS, 78, 1-21, 2013.

Saturn's moons, Titan and Enceladus, are two of the Solar System's most enigmatic bodies and are prime targets for future space exploration. Titan provides an analogue for many processes relevant to the Earth, more generally to outer Solar System bodies, and a growing host of newly discovered icy exoplanets. Processes represented include atmospheric dynamics, complex organic chemistry, meteorological cycles (with methane as a working fluid), astrobiology, surface liquids and lakes, geology, fluvial and aeolian erosion, and interactions with an external plasma environment. In addition, exploring Enceladus over multiple targeted flybys will give us a unique opportunity to further study the most active icy moon in our Solar System as revealed by Cassini and to analyse in situ its active plume with highly capable instrumentation addressing its complex chemistry and dynamics. Enceladus' plume likely represents the most accessible samples from an extra-terrestrial liquid water environment in the Solar system, which has far reaching implications for many areas of planetary and biological science. Titan with its massive atmosphere and Enceladus with its active plume are prime planetary objects in the Outer Solar System to perform in situ investigations. In the present paper, we describe the science goals and key measurements to be performed by a future exploration mission involving a Saturn-Titan orbiter and a Titan balloon, which was proposed to ESA in response to the call for definition of the science themes of the next Large-class mission in 2013. The mission scenario is built around three complementary science goals: (A) Titan as an Earth-like system; (B) Enceladus as an active cryovolcanic moon; and (C) Chemistry of Titan and Enceladus - clues for the origin of life. The proposed measurements would provide a step change in our understanding of planetary processes and evolution, with many orders of magnitude improvement in temporal, spatial, and chemical resolution over that which is possible with Cassini-Huygens. This mission concept builds upon the successes of Cassini-Huygens and takes advantage of previous mission heritage in both remote sensing and in situ measurement technologies. © 2014 Elsevier Ltd.

Titan, Saturn's largest satellite, is subject to solid body tides exerted by Saturn on the timescale of its orbital period. The tide-induced internal redistribution of mass results in tidal stress variations, which could play a major role for Titan's geologic surface record. We construct models of Titan's interior that are consistent with the satellite's mean density, polar moment-of-inertia factor, obliquity, and tidal potential Love number k 2 as derived from Cassini observations of Titan's low-degree gravity field and rotational state. In the presence of a global liquid reservoir, the tidal gravity field is found to be consistent with a subsurface water-ammonia ocean more than 180 km thick and overlain by an outer ice shell of less than 110 km thickness. The model calculations suggest comparatively low ocean ammonia contents of less than 5 wt % and ocean temperatures in excess of 255 K, i.e., higher than previously thought, thereby substantially increasing Titan's potential for habitable locations. The calculated diurnal tidal stresses at Titan's surface amount to 20 kPa, almost comparable to those expected at Enceladus and Europa. Tidal shear stresses are concentrated in the polar areas, while tensile stresses predominate in the near-equatorial, midlatitude areas of the sub- and anti-Saturnian hemispheres. The characteristic pattern of maximum diurnal tidal stresses is largely compliant with the distribution of active regions such as cryovolcanic candidate areas. The latter could be important for Titan's habitability since those may provide possible pathways for liquid water-ammonia outbursts on the surface and the release of methane in the satellite's atmosphere. Key Points Interior models and amplitude patterns of diurnal tidal stresses are calculated The diurnal tidal stress pattern is compliant with cryovolcanic candidate areas A warm, low-ammonia ocean could increase Titan's habitable potential ©2014. American Geophysical Union. All Rights Reserved.

TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (Montgolfière) and possibly several landing probes to be delivered through the atmosphere. © Springer Science + Business Media B.V. 2008.

Venus and Mars had likely liquid water on their surface for long periods of time during their history from which life could have originated and then adapted to live in ecological niches such as the subsurface for Mars and the atmosphere for Venus.

Even in one of the driest places on Earth, the Atacama Desert, life has found adaptive strategies to decreasing amounts of water: from refuges inside or below rocks as endoliths or hypoliths to inside salts in hygroscopic niches [1]. In the hyperarid core though, one of the last refuges for life are inside salt crusts using deliquescence as a water source or in the subsurface waiting for transitory episodes of increased moisture [2]. These adaptive strategies might also apply to a putative Martian life which endured a transition from a water rich past to the very harsh surface conditions of the present and giving us clues on where to best look for traces of life on the Red Planet. Salt crusts and salt nodules are particularly interesting targets in this regard because they reside on or very near the surface and are thus easily accessible to future robotic missions. In the Atacama, salt nodules have been shown to host photosynthetic organisms containing easily identifiable pigments by Raman spectroscopy such as carotenoids or scytonemin. Mostly composed of halite, they are associated with polygonated soils, but their formation processes are still not fully understood. Salt nodules occur in varying morphologies which can control micro-environmental conditions and possibly microbial colonization (habitation of “micro-niches”). One of the most damaging factors for life and its remains, both in the Atacama and on Mars, is solar radiation. To investigate the distribution of potential Raman signatures in micro-niches we mapped/reconstructed the sampling areas using photogrammetry techniques and plotted the dose received according to the nodules’ orientation. We then analysed salt nodules sections using Raman mapping to infer any relations between the amount of light received and the presence of detectable signal. Raman instruments are indeed part of the next two rover missions to Mars: ESA/Roscosmos’s ExoMars2020 and NASA’s Mars2020. To support and interpret future spectroscopic data correctly, a better understanding of potential habitable environments and putative biosignatures, using analogue environments such as the Atacama Desert, is of paramount importance. [1] A.F. Davila and D. Schulze-Makuch, Astrobiology, 16,159-168, (2016). [2] D. Schulze-Makuch, D. Wagner, S.P. Kounaves, K. Mangelsdorf, K.G. Devine, J.-P. de Vera, P. Schmitt-Kopplin, H.-P. Grossart, V. Parro, M. Kaupenjohann, A. Galy, B. Schneider, A. Airo, J. Frösler, A.F. Davila, F.L. Arens, L. Cáceres, F.S. Cornejo, D. Carrizo, et al., PNAS, 115, 2670–2675 (2018).

The geologic history of the multi-ringed Argyre impact basin and surroundings has been reconstructed on the basis of geologic mapping and relative-age dating of rock materials and structures. The impact formed a primary basin, rim materials, and a complex basement structural fabric including faults and valleys that are radial and concentric about the primary basin, as well as structurally-controlled local basins. Since its formation, the basin has been a regional catchment for volatiles and sedimentary materials as well as a dominant influence on the flow of surface ice, debris flows, and groundwater through and over its basement structures. The basin is interpreted to have been occupied by lakes, including a possible Mediterranean-sized sea that formed in the aftermath of the Argyre impact event The hypothesized lakes froze and diminished through time, though liquid water may have remained beneath the ice cover and sedimentation may have continued for some time. At its deepest, the main Argyre lake may have taken more than a hundred thousand years to freeze to the bottom even absent any heat source besides the Sun, but with impact-induced hydrothermal heat, geothermal heat flow due to long-lived radioactivities in early martian history, and concentration of solutes in sub-ice brine, liquid water may have persisted beneath thick ice for many millions of years. Existence of an ice-covered sea perhaps was long enough for life to originate and evolve with gradually colder and more hypersaline conditions. The Argyre rock materials, diverse in origin and emplacement mechanisms, have been modified by impact, magmatic, eolian, fluvial, lacustrine, glacial, periglacial, alluvial, colluvial, and tectonic processes. Post-impact adjustment of part of the impact-generated basement structural fabric such as concentric faults is apparent. Distinct basin-stratigraphic units are interpreted to be linked to large-scale geologic activity far from the basin, including growth of the Tharsis magmatic-tectonic complex and the growth into southern middle latitudes of south polar ice sheets. Along with the migration of surface and sub-surface volatiles towards the central part of the primaiy basin, the substantial difference in elevation with respect to the surrounding highlands and Tharsis and the Thaumasia highlands result in the trapping of atmospheric volatiles within the basin in the form of fog and regional or local precipitation, even today. In addition, the impact event caused long-term (millions of years) hydrothermal activity, as well as deep-seated basement structures that have tapped the internal heat of Mars, as conduits, for far greater time, possibly even today. This possibility is raised by the observation of putative open-system pingos and nearby gullies that occur in linear depressions with accompanying systems of faults and fractures. Long-term water and heat energy enrichment, complemented by the interaction of the nutrient-enriched primordial crustal and mantle materials favorable to life excavated to the surface and near-surface environs through the Argyre impact event, has not only resulted in distinct geomorphology, but also makes the Argyre basin a potential site of exceptional astrobiological significance. (C) 2015 Elsevier Inc. All rights reserved.