Previous models of microbial survival on the moon do not directly consider the permanently shadowed regions (PSRs). These regions shield their interiors from many of the biocidal factors encountered in space flight, such as UV irradiation and high temperatures, and this shielding reduces the rate at which microbial spores become nonviable. We applied the Lunar Microbial Survival Model (LMS, Schuerger et al., 2019) to the environment found inside PSRs at two craters targeted for exploration by the Artemis missions, Shackleton and Faustini. The model produced rates of reduction of -0.0815 and -0.0683 logs per lunation, respectively, which implies that it would take 30.0 years for Shackleton and 30.8 years for Faustini to accumulate a single Sterility Assurance Level of -12 logs of reduction. The lunar PSRs are therefore one of the least biocidal environments in the solar system and would preserve viable terrestrial microbial contamination for decades.

Volatile organic molecules and a complex organic refractory material were detected on the Moon and on lunar samples. The Moon's surface is exposed to a continuous flux of solar UV photons and fast ions, e.g. galactic cosmic rays (GCRs), solar wind (SW), and solar energetic particles (SEPs), that modify the physical and chemical properties of surface materials, thus challenging the survival of organic compounds. With this in mind, the aim of this work is to estimate the lifetime of organic compounds on the Moon's surface under processing by energetic particles. We performed laboratory experiments to measure the destruction cross of selected organic compounds, namely methane (CH4), 4 ), formamide (NH2CHO), 2 CHO), and an organic refractory residue, under simulated Moon conditions. Volatile species were deposited at low temperature (17- 18 K) and irradiated with energetic ions (200 keV) in an ultra-high vacuum chamber. The organic refractory residue was produced after warming up of a CO:CH4 4 ice mixture irradiated with 200 keV H+ + at 18 K. All the samples were analyzed in situ by infrared transmission spectroscopy. We found that destruction cross sections are strongly affected (up to one order of magnitude) by the dilution of a given organic in an inert matrix. Among the selected samples, organic refractory residues are the most resistant to radiation. We estimated the lifetime of organic compounds on the surface of the Moon by calculating the dose rate due to GCRs and SEPs at the Moon's orbit and by using the experimental cross values. Taking into account impact gardening, we also estimated the fraction of surviving organic material as a function of depth. Our results are compatible with the detection of CH4 4 in the LCROSS eject plume originating from layers deeper than about 0.7 m at the Moon's South Pole and with the identification of complex organic material in lunar samples collected by Apollo 17 mission.

Perchlorates have been found in the regolith of Mars and the Moon, in the ice of Europa, and in meteorites. Studying the processes of formation and destruction of these compounds is important both for understanding the geological and climatic evolution of a number of planets and bodies of the Solar System, and for assessing their habitability. To date, a number of processes for the synthesis of perchlorates under Martian conditions have been proposed, but these do not explain the perchlorate concentrations observed in the regolith and are not applicable to atmosphereless bodies, in particular Europa. We have studied the processes of synthesis and destruction of perchlorates during irradiation of ice and regolith models with high-energy electrons under conditions of low temperature (-50 degrees C) and in the absence of an atmosphere (at a pressure of 0.01 mbar). The data obtained indicate that perchlorates can be efficiently synthesized in the regolith of Mars and the surface layer of Europa ice under the influence of irradiation in the absence of a liquid phase or an atmosphere.

Extremophile organisms have been largely studied in Astrobiology. Among them, two antarctic plants emerge as good candidates to become colonizers of other celestial bodies, such as Mars and the Moon.The present research aimed to evaluate survival and growing capacity of Sanionia uncinata and Colobanthus quitensis on Martian (MGS-1) and Lunar(LMS-1) regolith simulants, underterrestrialconditions. Thesurvival responses of both species on the simulators and the original sampling site of Antarctic soil were observed during 15 days, in laboratory conditions at 'Comandante Ferraz' Station. Based on physiological parameters changes under the three soil conditions tested, our results suggest that Martian soil can be too harsh for plant growth, showing expressive decay, especially for C. quitensis. While lunar soil might provide more favorable conditions, with less observed changes, similarly to how they would in Antarctic soil from their natural habitat. This preliminary study provides resources and fosters knowledge about the possibility of these Antarctic species to survive in extraterrestrial environments, starting with soil parameters; and discusses the importance and use of Antarctic plants in astrobiology.

The comparative study of planetary systems is a unique source of new scientific insight: following the six key science questions of the Planetary Exploration, Horizon 2061 long-term foresight exercise, it can reveal to us the diversity of their objects (Question 1) and of their architectures (Question 2), help us better understand their origins (Question 3) and how they work (Question 4), find and characterize habitable worlds (Question 5), and ultimately, search for alien life (Question 6). But a huge knowledge gap exists which limits the applicability of this approach in the solar system itself: two of its secondary planetary systems, the ice giant systems of Uranus and Neptune, remain poorly explored.Starting from an analysis of our current limited knowledge of solar system ice giants and their systems in the light of these six key science questions, we show that a long-term plan for the space exploration of ice giants and their systems will greatly contribute to answer these questions. To do so, we identify the key measurements needed to address each of these questions, the destinations to choose (Uranus, Neptune, Triton or a subset of them), the combinations of space platform(s) and the types of flight sequences needed.We then examine the different launch windows available until 2061, using a Jupiter fly-by, to send a mission to Uranus or Neptune, and find that:(1) an optimized choice of platforms and flight sequences makes it possible to address a broad range of the key science questions with one mission at one of the planets. Combining an atmospheric entry probe with an orbiter tour starting on a high-inclination, low periapse orbit, followed by a sequence of lower inclination orbits (or the other way around) appears to be an optimal choice.(2) a combination of two missions to each of the ice giant systems, to be flown in parallel or in sequence, will address five out of the six key questions and establish the prerequisites to address the sixth one: searching for life at one of the most promising Ice Giant moons.(3) The 2032 Jupiter fly-by window, which offers a unique opportunity to implement this plan, should be considered in priority; if this window cannot be met, using the 2036 Jupiter fly-by window to send a mission to Uranus first, and then the 2045 window for a mission to Neptune, will allow one to achieve the same objectives; as a back-up option, one should consider an orbiter + probe mission to one of the planets and a close fly-by of the other planet to deliver a probe into its atmosphere, using the opportunity of a future mission on its way to Kuiper Belt Objects or the interstellar medium;(4) based on the examination of the habitability of the different moons by the first two missions, a third one can be properly designed to search for life at the most promising moon, likely Triton, or one of the active moons of Uranus.Thus, by 2061 the first two missions of this plan can be implemented and a third mission focusing on the search for life can be designed. Given that such a plan may be out of reach of a single national agency, international collaboration is the most promising way to implement it.

Endolithic micro-environments of rock are unique, ranging from high mountains and deep-sea floors to deserts and the Arctic and Antarctic regions colonized by high diversity of microbes. Endolithic microorganisms survive the extreme environmental conditions of rock pores and fissures with their survival strategies. In addition, the bulk rock provides mineral nutrients and protects the inhabitants from drastic ecological stresses from changes in the local conditions. Thus, endolithic microbes are at pivotal interface between geology and biology that offers a model system for unique microbial ecology, astrobiology, and geomicrobiology. This review provides comprehensive information on the diversity of endolithic microbial communities in cold, arid, aquatic, and terrestrial ecosystems and their survival strategies under ecological stresses. Furthermore, rock architecture for the colonization of endoliths, their biochemical functions and potential applications are discussed. It is clear that integrating modern molecular methods with physical and chemical analytical instrumentation will further advance our knowledge about endolithic microbial ecology, diversity, unique adaptive mechanisms, ecological functioning, and biochemical processes that shape the past, current, and future biosphere.

As new insights have emerged in recent decades about the dynamics of sea ice, researchers have sought to extend these insights to ice covered oceans in the solar system, where nonicy materials preserved in icy lithospheres may hold clues to solid-state convection and the possible presence of life. The recent study by Buffo et al. (2020), , considers the salt content of the ice covering Jupiter's moon Europa in the context of gravity drainage and mushy layer theory, and makes provocative predictions about the amounts of salts retained in the ice. A major question in such studies is how well the preservation and transport of salts in ice translates to the length and time scales of ices in ocean worlds. This work underlines the fundamental importance of including the role of chemistry in the modeling the structures and dynamics of the ice layers in ocean worlds. Plain Language Summary Earth's sea ice is a laboratory for inferring the workings of the icy lithospheres of the solar system's ocean moons, for example, Jupiter's moon Europa and Saturn's moons Enceladus and Titan. Recent work by Buffo et al. (2020) is one of the first efforts to quantify the potential entrainment of salts into the bulk of Europa's ice, extending the analysis of Earth's sea ice to the larger scales occurring in ocean world ices. This work is an important step toward understanding processes that may govern the potential for life in ocean worlds, and the potential for their icy lithospheres to hold onto clues of that life.

Carbon, hydrogen, nitrogen, oxygen, and sulfur are the main elements involved in the solid-phase chemistry of various astrophysical environments. Among these elements, sulfur chemistry is probably the least well understood. We investigated whether sulfur ion bombardment within simple astrophysical ice analogs (originating from H2O:CH3OH:NH3, 2:1:1) could trigger the formation of complex organosulfur molecules. Over 1100 organosulfur (CHNOS) molecular formulas (12% of all assigned signals) were detected in resulting refractory residues within a broad mass range (from 100 to 900 amu, atomic mass unit). This finding indicates a diverse, rich and active sulfur chemistry that could be relevant for Kuiper Belt objects (KBO) ices, triggered by high-energy ion implantation. The putative presence of organosulfur compounds within KBO ices or on other icy bodies might influence our view on the search of habitability and biosignatures.

Beyond Earth-like planets, moons can be habitable, too. No exomoons have been securely detected, but they could be extremely abundant. Young Jovian planets can be as hot as late M stars, with effective temperatures of up to 2000 K. Transits of their moons might be detectable in their infrared photometric light curves if the planets are sufficiently separated (greater than or similar to 10 AU) from the stars to be directly imaged. The moons will be heated by radiation from their young planets and potentially by tidal friction. Although stellar illumination will be weak beyond 5AU, these alternative energy sources could liquify surface water on exomoons for hundreds of Myr. A Mars-mass H2O-rich moon around beta Pic b would have a transit depth of 1.5 x 10(-3), in reach of near-future technology.

Galactic cosmic rays are a potential energy source to stimulate organic synthesis from simple ices. The recent detection of organic molecules at the polar regions of the Moon by LCROSS (Colaprete, A. et al. [2010]. Science 330, 463-468, http://dx.doi.org/10.1126/science.1186986), and possibly at the poles of Mercury (Paige, D.A. et al. [2013]. Science 339, 300-303, http://dx.doi.org/10.1126/science.1231106), introduces the question of whether the organics were delivered by impact or formed in situ. Laboratory experiments show that high energy particles can cause organic production from simple ices. We use a Monte Carlo particle scattering code (MCNPX) to model and report the flux of GCR protons at the surface of the Moon and report radiation dose rates and absorbed doses at the Moon's surface and with depth as a result of GCR protons and secondary particles, and apply scaling factors to account for contributions to dose from heavier ions. We compare our results with dose rate measurements by the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) experiment on Lunar Reconnaissance Orbiter (Schwadron, N.A. et al. [2012]. J. Geophys. Res. 117, E00H13, http://dx.doi.org/10.1029/2011JE003978) and find them in good agreement, indicating that MCNPX can be confidently applied to studies of radiation dose at and within the surface of the Moon. We use our dose rate calculations to conclude that organic synthesis is plausible well within the age of the lunar polar cold traps, and that organics detected at the poles of the Moon may have been produced in situ. Our dose rate calculations also indicate that galactic cosmic rays can induce organic synthesis within the estimated age of the dark deposits at the pole of Mercury that may contain organics. (C) 2013 Elsevier Inc. All rights reserved.