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Bacterial spores (Bacillus subtilis), cyanobacteria (Chroococcidiopsis sp.), and lichen (Xanthoria elegans) embedded in martian analogue rock (gabbro) were exposed to shock pressures between 5 and 50 GPa which is the range of pressures observed in martian meteorites. The survival of Bacillus subtilis and Xanthoria elegans up to 45 GPa and of Chroococcidiopsis sp. up to 10 GPa supports the possibility of transfer of life inside meteoroids between Mars and Earth and it implies the potential for the transfer of life from any Mars-like planet to other habitable planets in the same stellar system. Keywords: Mars; Impact processes; Astrobiology; Meteorites; Experimental techniques

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.spacepol.2006.08.006 Byline: Charles S Cockell (a), Gerda Horneck (b) Abstract: Building on an earlier article, establishment of a planetary park system for other planetary bodies is further developed. Reasons are elaborated for such a system to protect representative regions of other planetary bodies. Although a parks system might seem supererogatory, and an over-reaction to the currently very limited environmental impact of robotic and human exploration and settlement activities, four arguments are provided that suggest that such a system does have a value, even in advance of robotic and human missions. Planetary parks incorporate concepts of planetary protection, but they extend the reasons for practical protection policies beyond the utilitarian protection of scientific resources emphasized by planetary protection, into other utilitarian and intrinsic value arguments. Planetary parks might still allow for the development of non-park areas by commercial enterprise. Author Affiliation: (a) Open University, Milton Keynes, MK7 6AA, UK (b) German Aerospace Center DLR, Institute of Aerospace Medicine, D 51170 Cologne, Germany

Planetary protection policies designed to reduce the cross-transfer of life on spacecraft from one planet to another can either be formulated from the pragmatic instrumental needs of scientific exploration, or from ethical principles. I address planetary protection concerns by starting from a normative ethical framework for the treatment of microorganisms. This argues that they have intrinsic value at the level of the individual through to the level of the community, but at the individual level this ethic can only be theoretical. This approach yields a solution to the problem of the inevitable contamination of Mars by human explorers and suggests that in some instances the local contamination of other planets may be acceptable. An exception would be where this contamination would cause destruction of microbial ecosystems. Within the framework of such an ethic, the term 'planetary protection' may be normatively too narrow and 'planetary preservation' may better describe the activity of controlling cross-inoculation of planets. I discuss an example of a contamination event that might be ethically acceptable within the framework of 'preservation', but would be regarded as unacceptable under current planetary 'protection' guidelines. [C]2005 Elsevier Ltd. All rights reserved.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2004.12.009 Byline: Carmen Cordoba-Jabonero (a)(b), Maria-Paz Zorzano (b), Franck Selsis (b)(c), Manish R. Patel (d), Charles S. Cockell (e) Abstract: The biologically damaging solar ultraviolet (UV) radiation (quantified by the DNA-weighted dose) reaches the martian surface in extremely high levels. Searching for potentially habitable UV-protected environments on Mars, we considered the polar ice caps that consist of a seasonally varying CO.sub.2 ice cover and a permanent H.sub.2O ice layer. It was found that, though the CO.sub.2 ice is insufficient by itself to screen the UV radiation, at [approximately equal to]1 m depth within the perennial H.sub.2O ice the DNA-weighted dose is reduced to terrestrial levels. This depth depends strongly on the optical properties of the H.sub.2O ice layers (for instance snow-like layers). The Earth-like DNA-weighted dose and Photosynthetically Active Radiation (PAR) requirements were used to define the upper and lower limits of the northern and southern polar Radiative Habitable Zone (RHZ) for which a temporal and spatial mapping was performed. Based on these studies we conclude that photosynthetic life might be possible within the ice layers of the polar regions. The thickness varies along each martian polar spring and summer between [approximately equal to]1.5 and 2.4 m for H.sub.2O ice-like layers, and a few centimeters for snow-like covers. These martian Earth-like radiative habitable environments may be primary targets for future martian astrobiological missions. Special attention should be paid to planetary protection, since the polar RHZ may also be subject to terrestrial contamination by probes. Author Affiliation: (a) Instituto Nacional de Tecnica Aeroespacial (INTA), Area de Investigacion e Instrumentacion Atmosferica, Ctra. Ajalvir km. 4, Torrejon de Ardoz, 28850 Madrid, Spain (b) Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir km. 4, Torrejon de Ardoz, 28850 Madrid, Spain (c) Centre de Recherche Astronomique de Lyon (CRAL), Ecole normale Superieure (ENSL), 47, Allee d'Italie, F-69364 Lyon Cedex 7, France (d) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK (e) British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK

Ultraviolet radiation is more damaging on the surface of Mars than on Earth because of the lack of an ozone shield. We investigated micro-habitats in which UV radiation could be reduced to levels similar to those found on the surface of present-day Earth, but where light in the photosynthetically active region (400-700 nm) would be above the minimum required for photosynthesis. We used a simple radiative transfer model to study four micro-habitats in which such a theoretical Martian Earth-like Photosynthetic Zone (MEPZ) might exist. A favorable radiation environment was found in martian soils containing iron, encrustations of halite, polar snows and crystalline rocks shocked by asteroid or comet impacts, all of which are known habitats for phototrophs on Earth. Although liquid water and nutrients are also required for life, micro-environments with favorable radiation environments for phototrophic life exist in a diversity of materials on Mars. This finding suggests that the lack of an ozone shield is not in itself a limit to the biogeographically widespread colonization of land by photosynthetic organisms, even if there are no other UV-absorbers in the atmosphere apart from carbon dioxide. When applied to the Archean Earth, these data suggest that even with the worst-case assumptions about the UV radiation environment, early land masses could have been colonized by primitive photosynthetic organisms. Such zones could similarly exist on anoxic extra-solar planets lacking ozone shields. Keywords: Exobiology; Solar radiation; Extrasolar planets; Impact processes; Mars; Atmosphere

December 25th 2003 will see the Beagle 2 lander arrive at the surface of Mars in the Isidis region, allowing for the first time in situ measurements of ultraviolet (UV) flux directly from the surface of Mars through the use of a sensor designed as part of a miniaturised environmental package. The expected conditions the sensor will experience are studied here, and the detection signatures for phenomenon such as dust devils, [H.sub.2]O clouds ands near-surface fogs are presented. The beginning and end of mission surface fluxes show little variation, though the period towards mid-nominal mission does experience a maximum in total daily dose levels. Diurnal profiles are calculated highlighting the effects of increased scattering towards shorter wavelengths. A possible dust storm scenario is presented, and the effect upon component UV fluxes is shown to reverse the relative contributions of direct and diffuse components of the total UV flux. The presence of cloud formation above the landing site will be detectable though the observation of elevated diffuse/direct flux ratios. Near-surface morning fogs show a characteristic 'dip' in the morning profile when compared to clear mornings, allowing their detection on cloud-free mornings through post-event analysis of long term data. Predicted Phobos eclipses are investigated at each of the sensor centre wavelengths, and show greatest reduction in relative intensity at short wavelengths. Observations of near-miss eclipse events will also be possible, through monitoring of the diffuse UV flux. Dust devil encounters are shown to create a double minima lightcurve, with the depth of the minima dependent upon the total dust loading of the vortex. The effects of these changing conditions on DNA-weighted irradiances are investigated. Possible dust storms provide the greatest increase in biological protection, whereas expected cloud formations at the Beagle 2 site are found to offer negligible protection. Within just five minutes of landing > 95% of any Bacillus subtilis-like bacteria present on the surface of the craft will have lost viability. Keywords: Mars; Mars, atmosphere: Radiative transfer; Ultraviolet observations; Exobiology

Because of the ubiquity of subsurface microbial life on Earth, examination of the subsurface of Mars could provide an answer to the question of whether microorganisms exist or ever existed on that planet. Impact craters provide a natural mechanism for accessing the deep substrate of Mars and exploring its exobiological potential. Based on equations that relate impact crater diameters to excavation depth we estimate the observed crater diameters that are required to prospect to given depths in the martian subsurface and we relate these depths to observed microbiological phenomena in the terrestrial subsurface. Simple craters can be used to examine material to a depth of ~270 m. Complex craters can be used to reach greater depths, with craters of diameters [greater than or equal to] 300 km required to reach depths of 6 km or greater, which represent the limit of the terrestrial deep subsurface biosphere. Examination of the ejecta blankets of craters between 17.5 and 260 kan in diameter would provide insights into whether there is an extant, or whether there is evidence of an extinct, deep subsurface microbiota between 500 and 5000 m prior to committing to large-scale drilling efforts. At depths Key Words: impacts; Mars; life; excavation; critical depth; drilling; paleolacustrine.

The ultraviolet radiation environment of main sequence stars might be a factor in determining the suitability of extrasolar planets for biological evolution and the subsequent radiation of life in exposed habitats. Assuming the validity of the carbon-water chauvinism, the absorbance of DNA in the UV region of the spectrum is used as a theoretical biological dosimeter to elucidate in more detail the photobiological parameter space of anoxic planets orbiting F, G, and K main sequence stars. Planets within the habitable zones of K main sequence stars have particularly favorable UV environments, with biochemically effective irradiances an order of magnitude lower than those believed to have existed on the surface of Archean Earth. Even using the UV shielding and repair habits of present-day terrestrial organisms, the survivability of the photobiological environment of anoxic K star planets can be demonstrated. The biochemically effective irradiances received in the F star radiation environment are more severe, being 6 to 27 times higher than on Archean Earth. Nevertheless, a combination of UV mitigation strategies seen on the present-day Earth suggest that UV radiation is not a constraint on life even in the inner region of the habitable zone. Life in an ocean on an F-star planet could experience a UV radiation regime similar even to that for present-day Earth. These calculations, although limited by our assumptions on the course of biochemical evolution and the UV absorbance of complex extraterrestrial molecules, suggest that life can survive the UV radiation environments of most extrasolar planets.

In preparation for the eventual manufacture and storage of food in space, we conducted a set of experiments to determine the effect of a rapid catastrophic depressurisation on a range of common foodstuffs. The experiment tested the hypothesis that rapid depressurisation would cause explosive destruction or boiling of stored foodstuffs. We tested 18 types of fruit, 18 types of vegetables, 4 types of nuts, 4 types of fish, 10 types of raw and prepared meat, chicken eggs, 9 types of cheese and 8 other foods including rice and lentils. They were exposed to depressurisation from atmospheric pressure to 6 mb in 5.67 min to simulate a rapid depressurisation event on Mars. We found most of the tested produce to be robust against depressurisation. No explosive rupture or failure was observed in any of the tested items. Introduction of cuts into the produce resulted in localised bubbling, for example in tomatoes, and bubbling was observed at the site of bruising, for example in bananas and pears. At pressures greater than ∼30 mb we attribute this to outgassing and below this pressure to a combination of outgassing and boiling and we present a general model to describe these findings. Raw meat (such as ham), fish (such as salmon) and some cheeses (such as Mozzarella) bubbled at their surfaces, causing the surface to dry. The most profound changes were observed in sausages, haggis and chicken in which air expanded beneath the skins, stretching the skin and causing wrinkling when repressurisation occurred, although the overall integrity of the food was not altered. We conclude that a rapid depressurisation event in a food storage unit would not cause catastrophic physical disruption of food. However, secondary protection inside closed containers is advisable for fish, raw and prepared meats, fruits and vegetables with observable bruising or damage, to protect against drying during a depressurisation event. Our data show the potential for low pressure storage of food. • Observations on the effects of rapid depressurisation on common foodstuffs. • Demonstration that no foodstuffs showed catastrophic loss of structural integrity on rapid depressurisation. • Discussion on generalised model for understanding effects of depressurisation on foods and behaviour of food fluids. • Discussion on further areas of research on food storage in space. [ABSTRACT FROM AUTHOR]

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations. Key Words: atmospheres; evolution; exobiology; Mars; photochemistry; radiative transfer.

Geobiology, and in particular mineral–microbe interactions, has a significant role to play in current and future space exploration. This includes the search for biosignatures in extraterrestrial environments, and the human exploration of space. Microorganisms can be exploited to advance such exploration, such as through biomining, maintenance of life-support systems, and testing of life-detection instrumentation. In view of these potential applications, a European Space Agency (ESA) Topical Team “Geobiology in Space Exploration” was developed to explore these applications, and identify research avenues to be investigated to support this endeavour. Through community workshops, a roadmap was produced, with which to define future research directions via a set of 15 recommendations spanning three key areas: Science, Technology, and Community. These roadmap recommendations identify the need for research into: (1) new terrestrial space-analogue environments; (2) community level microbial–mineral interactions; (3) response of biofilms to the space environment; (4) enzymatic and biochemical mineral interaction; (5) technical refinement of instrumentation for space-based microbiology experiments, including precursor flight tests; (6) integration of existing ground-based planetary simulation facilities; (7) integration of fieldsite biogeography with laboratory- and field-based research; (8) modification of existing planetary instruments for new geobiological investigations; (9) development of in situ sample preparation techniques; (10) miniaturisation of existing analytical methods, such as DNA sequencing technology; (11) new sensor technology to analyse chemical interaction in small volume samples; (12) development of reusable Lunar and Near Earth Object experimental platforms; (13) utility of Earth-based research to enable the realistic pursuit of extraterrestrial biosignatures; (14) terrestrial benefits and technological spin-off from existing and future space-based geobiology investigations; and (15) new communication avenues between space agencies and terrestrial research organisations to enable this impact to be developed. [ABSTRACT FROM AUTHOR]

Abstract: Anaerobic microbial metabolisms found on the Earth are the most plausible candidates for understanding potentially analogous energy gathering metabolisms on Mars. The iron-rich nature of Mars raises questions on whether the planet could support energy acquisition by iron-cycling microorganisms. This review paper addresses what is known about the redox couples that support microbial iron cycling on Earth, and evaluates evidence to date of the presence or absence of relevant redox constituents on Mars. We give particular focus to iron reduction. These constituents include the presence and prevalence of ferric iron-bearing minerals that may serve as terminal electron acceptors, and the likelihood of organic compounds (exogenous and endogenous) or hydrogen residing in the near- or sub-surface as a source of electron donors. Whilst it is feasible that redox couples for iron cycling may exist, or have existed in the past, current knowledge suggests that for chemolithotrophs (iron oxidation) Mars may be an electron acceptor limited world and that for chemoorganotrophs (iron reduction) Mars may be limited in widespread, readily available electron donors, particularly in its subsurface. There are several major limitations in this assessment due to lack of experimental data on Earth, and lack of measurements on Mars. We outline a series of high priority in-situ measurements that are necessary to fully evaluate the potential for a Martian biological iron cycle. Our conclusions also apply to the search for a Martian biological sulphur cycle. [Copyright &y& Elsevier]

The search for life on other planets usually makes the assumption that where there is a habitat, it will contain life. On the present-day Earth, uninhabited habitats (or vacant habitats) are rare, but might occur, for example, in subsurface oils or impact craters that have been thermally sterilized in the past. Beyond Earth, vacant habitats might similarly exist on inhabited planets or on uninhabited planets, for example on a habitable planet where life never originated. The hypothesis that vacant habitats are abundant in the Universe is testable by studying other planets. In this review, I discuss how the study of vacant habitats might ultimately inform an understanding of how life has influenced geochemical conditions on Earth. [ABSTRACT FROM AUTHOR]

Abstract: The regolith of other planetary bodies, such as the Moon and Mars, is rich in inorganic elements that could potentially be exploited for space applications. Lithotrophic microorganisms that are capable of utilising rocks as a growth substrate, and facilitate the extraction of elements, are ideal candidates for in-situ resource use. Of particular interest are the cyanobacteria, which have been suggested for applications, such as oxygen, fuel and biomass production, nutrient acquisition, and feedstock provisions. In this study, Gloeocapsa strain OU_20, isolated from a rock-dwelling community exposed to low Earth orbit; Leptolyngbya strain OU_13 and Phormidium strain OU_10, both isolated from a rock-dwelling community exposed to Mars simulated conditions; Chroococcidiopsis 029; Arthrospira platensis; Synechococcus elongatus; and Anabaena cylindrica, were examined as potential organisms for space in-situ resource use. Volcanic rocks, including basalt (low in SiO2) analogous to martian and lunar basalt, rhyolite (high in SiO2), and anorthosite analogous to lunar regolith were used as growth substrates. The growth rate and rock dissolution were significantly lower with rhyolite demonstrating the importance of silica content in defining the potential for in-situ resource use. Biological weathering resulted in the release of bio-essential elements from the rock matrix, highlighting the potential of cyanobacteria for applications such as bio-mining and nutrient acquisition, on other planets. A. cylindrica produced the maximum biomass with the three rock-types and the optimal value was obtained with the basalt. Exposure experiments demonstrated that A. cylindrica, Chroococcidiopsis 029, Gloeocapsa strain OU_20, Phormidium strain OU_10, and Leptolyngbya strain OU_13 were able to survive 28 days of exposure to desiccation and Mars simulated conditions, which is beneficial in case of system malfunction and for storage. The results from this study indicate that cyanobacteria can potentially be used for in-situ planetary resource acquisition. [Copyright &y& Elsevier]

Geomicrobiology investigates the interactions of microorganisms with geological substrates, and this branch of microbiology has enormous potential in the exploration and settlement of space. Microorganisms can be used to extract useful elements from extraterrestrial materials for industrial processes or for use as nutrients in life support systems. In addition, microorganisms could be used to create soil from lunar and Martian rocks. Furthermore, understanding the interactions of microorganisms with rocks is essential for identifying mineral biomarkers to be used in the search for life on other planetary bodies. Increasing space exploration activities make geomicrobiology an important applied science beyond Earth. [Copyright &y& Elsevier]

Abstract: Microorganisms can be used as model systems for studying biological responses to extraterrestrial conditions; however, the methods for studying their response are extremely challenging. Since the first high altitude microbiological experiment in 1935 a large number of facilities have been developed for short- and long-term microbial exposure experiments. Examples are the BIOPAN facility, used for short-term exposure, and the EXPOSE facility aboard the International Space Station, used for long-term exposure. Furthermore, simulation facilities have been developed to conduct microbiological experiments in the laboratory environment. A large number of microorganisms have been used for exposure experiments; these include pure cultures and microbial communities. Analyses of these experiments have involved both culture-dependent and independent methods. This review highlights and discusses the facilities available for microbiology experiments, both in space and in simulation environments. A description of the microorganisms and the techniques used to analyse survival is included. Finally we discuss the implications of microbiological studies for future missions and for space applications. [Copyright &y& Elsevier]

Abstract: In the coming decades the detection of Earth-like extrasolar planets, either apparently lifeless or exhibiting spectral signatures of life, will encourage design studies for craft to visit them. These missions will require the elaboration of an interstellar planetary protection protocol. Given a specific dose required to sterilize microorganisms on a spacecraft, a critical mean velocity can be determined below which a craft becomes self-sterilizing. This velocity is calculated to be below velocities previously projected for interstellar missions, suggesting that an active sterilization protocol prior to launch might be required. Given uncertainties in the surface conditions of a destination extrasolar planet, particularly at microscopic scales, the potential for unknown biochemistries and biologies elsewhere, or the possible inoculation of a lifeless planet that is habitable, then both lander and orbiter interstellar missions should be completely free of all viable organisms, necessitating a planetary protection approach applied to orbiters and landers bound for star systems with unknown local conditions for habitability. I discuss the case of existing craft on interstellar trajectories – Pioneer 10, 11 and Voyager 1 and 2. [Copyright &y& Elsevier]

Microorganisms from diverse environments actively bore into rocks, contributing significantly to rock weathering. Carbonates are the most common substrate into which they bore, although there are also reports of microbial borings into volcanic glass. One of the most intriguing questions in microbial evolutionary biology is why some microorganisms bore. A variety of possible selection pressures, including nutrient acquisition, protection from UV radiation and predatory grazing could promote boring. None of these pressures is mutually exclusive and many of them could have acted in concert with varying strengths in different environments to favour the development of microorganisms that bore. We suggest that microbial boring might have begun in some environments as a mechanism against entombment by mineralization. [Copyright &y& Elsevier]

Abstract: The last decade has been marked by a large number of studies focused on understanding the distribution of microorganisms in volcanic environments. These studies are motivated by the desire to elucidate how the geochemically extreme conditions of such environments can influence microbial diversity both on the surface and in the subsurface of the Earth. The exploration of microbial community diversity has generally not relied on culture-dependent methods, but has been carried out using environmental DNA extraction. Because of the large diversity of chemically and physically complex samples, extracting DNA from volcanic environments is technically challenging. In view of the emerging literature, and our own experience in the optimisation of methods for DNA extraction from volcanic materials, it is timely to provide a methodological comparison. This review highlights and discusses new insights and methods published on DNA extraction methods from volcanic samples, considering the different volcanic environments. A description of a recent method for DNA extraction from basalt and obsidian glass rock samples from Iceland is included. Finally, we discuss these approaches in the wider context of modern work to understand the microbial diversity of volcanic environments. [Copyright &y& Elsevier]

Commonly viewed solely as agents of destruction, asteroid and comet impact events can also have a beneficial influence on processes from the molecular to the evolutionary scale. On the heavily bombarded early Earth, impacts might have delivered and caused the synthesis of prebiotic compounds that eventually led to life. At the organismal and ecosystem level, impact events can provide new habitats through the shock processing of target materials and by enhancing water availability, such as within intracrater lakes. At the evolutionary level, by destroying entire groups of organisms, impacts might have been instrumental in enabling the rise of new groups, such as the dinosaurs and mammals. Here, we synthesize the emerging literature on the beneficial effects of impacts to provide a novel perspective on these extraterrestrial agents of biological change. [Copyright &y& Elsevier]

The extreme conditions of all extraterrestrial environments restrict freedom of movement and encourage social, political and economic arrangements friendly to tyranny. However, deliberately engineered measures might be taken to maximise liberty in the space environment. For example, space settlements can be engineered to maximise the number of oxygen, food, water and power systems to disallow coercive regimes the opportunity to control single machines on which entire settlements depend. Spacesuits can be engineered to be easily manufactured and maintained, thus maximising the number available to occupants of a settlement and minimising the extent to which bespoke and difficult-to-service suits restrict freedom of movement. Other examples of this approach to engineering are provided, which we might term 'freedom engineering'. Although attempts to deliberately engineer freedom into a settlement turn on the definition of 'freedom', it is suggested that objective criteria in the enhancement of certain types of individual and collective liberty can be used to determine when an act of freedom engineering is likely to be beneficial for a settlement. The space policy implications of these ideas are discussed. [ABSTRACT FROM AUTHOR]

Future human missions to the Moon and Mars will require astronauts to perform science-focused surface exploration in complex geological environments. However, the scientific expertise required for these activities is uncommon in the astronaut corps. PANGAEA (Planetary ANalogue Geological and Astrobiological Exercise for Astronauts) is a field training course designed by the European Space Agency (ESA) that addresses the topics of geological and astrobiological planetary exploration. The course intends to impart the essential basic theoretical and practical knowledge of geology and astrobiology, in order to prepare astronauts for advanced mission specific training. Significant focus is given to skills in areas relevant to future missions, such as scientific decision-making, working with a remotely located science team, and efficient documentation. For this reason, although portions of the course are taught in classrooms, developing independent field skills in analogue geological environments is a key part of the training. Classroom and field lessons are tightly interwoven in the course structure with a time separation often of only hours between being introduced to a concept in the classroom and seeing it in the field. The course forms part of the basic and pre-assignment training for European astronauts and is open to trainees from all other agencies. PANGAEA has been running since 2016, with participants including ESA and NASA astronauts, and Roscosmos cosmonauts, as well as mission designers, operations personnel and engineers. The primary field sites selected for the course are Permo-Triassic sedimentary sequences in the Italian Dolomites, impact lithologies in the Ries Crater, Germany, a comprehensive suite of volcanic deposits in Lanzarote, Spain, and anorthosite outcrops in Lofoten, Norway. Each is used as a base to deliver the main learning sessions, respectively: 1) Earth geology, rock recognition and sedimentology on Earth and Mars, 2) Lunar geology and impact cratering, 3) volcanism on Earth, Moon, and Mars, and astrobiology 4) intrusive rocks and lunar primordial crustal evolution. The four sessions are designed to increase trainee autonomy in field geology by including guided or autonomously executed geological traverses and practicing of sampling techniques. Whilst PANGAEA's primary focus is astronaut training, where appropriate and complementary to this training, technologies being developed for future missions are used and tested by the trainees during geological traverses. This provides an opportunity to evaluate the performance of new equipment and software in analogue field environments, whilst also providing trainees with experience using technology that might support future missions. • ESA PANGAEA trains astronauts in planetary and field geology. • The training is focused in acquiring practical skills in geological exploration. • Moon/Mars analogue geological sites around Europe are used as training sites. • PANGAEA provides basic skills to prepare for future mission specific training. [ABSTRACT FROM AUTHOR]

Abstract: With the prospect of humans returning to Moon by the end of the next decade, considerable attention is being paid to technologies required to transport astronauts to the lunar surface and then to be able to carry out surface science. Recent and ongoing initiatives have focused on scientific questions to be asked. In contrast, few studies have addressed how these scientific priorities will be achieved. In this contribution, we provide some of the lessons learned from the exploration of the Haughton impact structure, an ideal lunar analogue site in the Canadian Arctic. Essentially, by studying how geologists carry out field science, we can provide guidelines for lunar surface operations. Our goal in this contribution is to inform the engineers and managers involved in mission planning, rather than the field geology community. Our results show that the exploration of the Haughton impact structure can be broken down into 3 distinct phases: (1) reconnaissance; (2) systematic regional-scale mapping and sampling; and (3) detailed local-scale mapping and sampling. This break down is similar to the classic scientific method practiced by field geologists of regional exploratory mapping followed by directed mapping at a local scale, except that we distinguish between two different phases of exploratory mapping. Our data show that the number of stops versus the number of samples collected versus the amount of data collected varied depending on the mission phase, as does the total distance covered per EVA. Thus, operational scenarios could take these differences into account, depending on the goals and duration of the mission. Important lessons learned include the need for flexibility in mission planning in order to account for serendipitous discoveries, the highlighting of key “science supersites” that may require return visits, the need for a rugged but simple human-operated rover, laboratory space in the habitat, and adequate room for returned samples, both in the habitat and in the return vehicle. The proposed set of recommendations ideally should be tried and tested in future analogue missions at terrestrial impact sites prior to planetary missions. [Copyright &y& Elsevier]

We examined the possibility that, during short-term refrigerated storage, microbial communities continue to biodegrade individual lipid biomarkers in an intact core section of Early Eocene consolidated marlstone sediments from the hydrothermal system overlying the Chicxulub impact crater (Yucatán, Mexico). Amplicon sequencing of environmental 16S rRNA obtained from the core samples revealed a high relative abundance of amplicon sequence variants (ASVs) related to known hydrocarbon degraders, notably Halomonas and Marinobacter. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2) predicted that Marinobacter and a subset of less abundant bacteria (e.g., Alcanivorax) have the genomic potential to anaerobically degrade hydrocarbons via dissimilatory nitrate reduction to ammonia. The variability in the relative abundance of these taxa showed strong positive Pearson correlations (Pearson's r > 0.5) with quantitative changes in the most bioavailable non-sulfurized compounds, notably polycyclic aromatic hydrocarbons (PAHs) and isorenieratane. Moderate positive Pearson correlations (r values between ∼0.3 and ∼0.5) were observed between microbial taxa and compounds that have undergone early abiotic diagenetic sulfurization (e.g., hopanes, n -alkanes and steranes). These results suggest that non-sulfurized biomarkers may be subject to continued biodegradation in marine sedimentary rocks during short-term refrigerated storage. [ABSTRACT FROM AUTHOR]

Life on Earth is limited by physical and chemical extremes that define the ‘habitable space’ within which it operates. Aside from its requirement for liquid water, no definite limits have been established for life under any extreme. Here, we employ growth data published for 67 prokaryotic strains to explore the limitations for microbial life under combined extremes of temperature, pH, salt (NaCl) concentrations, and pressure. Our review reveals a fundamental lack of information on the tolerance of microorganisms to multiple extremes that impedes several areas of science, ranging from environmental and industrial microbiology to the search for extraterrestrial life. [ABSTRACT FROM AUTHOR]

Abstract: Focused ion beam (FIB) sample preparation in combination with subsequent transmission electron microscopy (TEM) analysis are powerful tools for nanometre-scale examination of the cell–mineral interface in bio-geological samples. In this study, we used FIB-TEM to investigate the interaction between a cyanobacterium (Hassallia byssoidea) and a common sheet silicate mineral (biotite) following a laboratory-based bioweathering, incubation experiment. We discuss the FIB preparation of cross-sections of the cell mineral interface for TEM investigation. We also establish an electron fluence threshold (at 200keV) in biotite for the transition from scanning (S)TEM electron beam induced contamination build up on the surface of biotite thin sections to mass loss, or hole-drilling within the sections. Working below this threshold fluence nanometre-scale structural and elemental information has been obtained from biotite directly underneath cyanobacterial cells incubated on the biotite for 3 months. No physical alteration of the biotite was detected by TEM imaging and diffraction with little or no elemental alteration detected by STEM–energy dispersive X-ray (EDX) elemental line-scanning or by energy filtered TEM (EF-TEM) jump ratio elemental mapping. As such we present evidence that the cyanobacterial strain of H. byssoidea did not cause any measurable alteration of biotite, within the resolution limits of the analysis techniques used, after 3 months of incubation on its surface. [Copyright &y& Elsevier]

Abstract: The generic concept of the artificial meteorite experiment STONE is to fix rock samples bearing microorganisms on the heat shield of a recoverable space capsule and to study their modifications during atmospheric re-entry. The STONE-5 experiment was performed mainly to answer astrobiological questions. The rock samples mounted on the heat shield were used (i) as a carrier for microorganisms and (ii) as internal control to verify whether physical conditions during atmospheric re-entry were comparable to those experienced by “real” meteorites. Samples of dolerite (an igneous rock), sandstone (a sedimentary rock), and gneiss impactite from Haughton Crater carrying endolithic cyanobacteria were fixed to the heat shield of the unmanned recoverable capsule FOTON-M2. Holes drilled on the back side of each rock sample were loaded with bacterial and fungal spores and with dried vegetative cryptoendoliths. The front of the gneissic sample was also soaked with cryptoendoliths. The mineralogical differences between pre- and post-flight samples are detailed. Despite intense ablation resulting in deeply eroded samples, all rocks in part survived atmospheric re-entry. Temperatures attained during re-entry were high enough to melt dolerite, silica, and the gneiss impactite sample. The formation of fusion crusts in STONE-5 was a real novelty and strengthens the link with real meteorites. The exposed part of the dolerite is covered by a fusion crust consisting of silicate glass formed from the rock sample with an admixture of holder material (silica). Compositionally, the fusion crust varies from silica-rich areas (undissolved silica fibres of the holder material) to areas whose composition is “basaltic”. Likewise, the fusion crust on the exposed gneiss surface was formed from gneiss with an admixture of holder material. The corresponding composition of the fusion crust varies from silica-rich areas to areas with “gneiss” composition (main component potassium-rich feldspar). The sandstone sample was retrieved intact and did not develop a fusion crust. Thermal decomposition of the calcite matrix followed by disintegration and liberation of the silicate grains prevented the formation of a melt. Furthermore, the non-exposed surface of all samples experienced strong thermal alterations. Hot gases released during ablation pervaded the empty space between sample and sample holder leading to intense local heating. The intense heating below the protective sample holder led to surface melting of the dolerite rock and to the formation of calcium-silicate rims on quartz grains in the sandstone sample. [Copyright &y& Elsevier]

Abstract: Cyanobacteria are ubiquitous, ecologically important and phylogenetically diverse components of the phytoplankton of marine and freshwater environments, as well as some extreme settings such as hot springs, and highly saline and ice covered lakes. They have also been shown to be amongst the most prolific sources of bacteriohopanepolyols (BHPs; pentacyclic triterpenoids produced by taxa within the bacterial domain and especially in the proteobacteria) and are considered to be the most environmentally significant source of C-2 methylated hopanoids. The compounds therefore have the potential for wide application in studies of the contemporary marine carbon cycle as well as providing a means of tracking cyanobacteria back through geological history where organic matter is well preserved. Here, we have used liquid chromatography ion-trap mass spectrometry to investigate the intact BHP distributions in cultured cyanobacteria (pure cultures and enrichment cultures) and in a variety of environmental settings. We present data on the detection and characterisation of BHP structures in 26 cultured cyanobacteria (ranging from marine and freshwater species to isolates from hydrothermal systems), 10 of which have not been tested for hopanoid production. Of the 58 strains of cyanobacteria studied to date, 49 have been shown to produce BHPs and 21 of them produce C-2 methylated BHPs. We show that, paradoxically, hopanoid production appears to be absent from the most prolific marine picocyanobacteria, although two important marine nitrogen fixing species, Trichodesmium and Crocosphaera, do produce BHPs. The diversity of BHP distributions in a range of environmental samples, including lake sediments, bacterial mats from lakes and hydrothermal springs, and samples from hot and cold deserts, including endoliths, hypoliths and small stromatolitic structures is also described. [Copyright &y& Elsevier]

Water is a fundamental requirement for life. Its biological availability is partly determined by water activity and thus measuring this parameter is vital in industries such as food, agriculture and beyond. Apart from its terrestrial applications, water activity is also important in planetary exploration, for example in determining habitability in the subsurface of Mars, icy moons and other regions of interest in the Solar System. This paper reports a miniaturized water activity sensor for measurement in planetary environments. In line with space instrumentation constraints, objectives included minimizing the weight and dimensions of the sensor system, lowering the power consumption, enabling smaller sample volumes and achieving faster measurement time. We describe the design, construction, testing and field validation of this instrument. • Miniaturised water activity sensor for space exploration. • Water activity design was constructed for field applications. • Boulby mine served as the field sites where the instrument was demonstrated. • Time response of the instrument was much better compared to the commercial system. • Useful for ongoing habitability studies of ancient aqueous environments in Solar system like Mars and Icy moons. [ABSTRACT FROM AUTHOR]