Astrobiology最新文献

{"title":"A Microbial Survival Model for the Permanently Shadowed Regions of the Moon Shows Long-Term Survival of Terrestrial Microbial Contamination.","authors":"John E Moores, Jacob L Kloos, Grace Bischof, Conor W Hayes, Andrew C Schuerger","doi":"10.1089/ast.2024.0165","DOIUrl":"10.1089/ast.2024.0165","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"391-394"},"PeriodicalIF":3.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144141324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of Photochemical Haze Refractive Indices and Hygroscopicity: Influence of CO₂ in CH₄/H₂S/N₂ Mixtures.","authors":"Kevin T Jansen, Nathan W Reed, Eleanor C Browne, Margaret A Tolbert","doi":"10.1089/ast.2024.0142","DOIUrl":"10.1089/ast.2024.0142","url":null,"abstract":"<p><p>Atmospheric organic hazes are widespread across various planetary bodies and have significant effects on both the surface and atmosphere. In this study, we investigate the optical and hygroscopic properties of organic hazes formed through photochemical processes. The hazes were generated from the irradiation of mixtures that contained molecular nitrogen (N₂), methane (CH₄), hydrogen sulfide (H₂S), and varying amounts of carbon dioxide (CO₂) to mimic early Earth-like conditions. In the absence of CO₂, the photochemical haze absorbed radiation at 405 nm. In contrast, the incorporation of CO₂ into the precursor gas mixtures resulted in hazes with reduced absorption at 405 nm. This decrease in absorption was due to the formation of non-absorbing inorganic salts and/or a change in organic composition; however, the exact composition is not fully known. Further, we observed that these hazes exhibited varying tendencies to uptake water, with non-CO₂ hazes showing no water uptake, while CO₂ hazes could absorb water and increase in size. Consequently, under humid conditions, the increased size of the haze enhanced its ability to scatter light and would thus promote cooling of a planetary atmosphere. Both the change in refractive indices and the increased hygroscopicity would contribute to greater cooling effects with higher CO₂ levels. In addition, the ability of the haze to uptake water would facilitate the particles acting as cloud condensation nuclei, potentially leading to the wet deposition of nutrients to a planet's surface that could help facilitate the emergence of life.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"395-403"},"PeriodicalIF":3.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144198183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Challenges and Opportunities in Using Amino Acids to Decode Carbonaceous Chondrite and Asteroid Parent Body Processes.","authors":"José C Aponte, Hannah L McLain, Daniel Saeedi, Amirali Aghazadeh, Jamie E Elsila, Daniel P Glavin, Jason P Dworkin","doi":"10.1089/ast.2025.0017","DOIUrl":"10.1089/ast.2025.0017","url":null,"abstract":"<p><p>Carbonaceous chondrite (CC) meteorites are fragments of planetesimals that hold clues about the early solar system's organic matter. Amino acids are key to life on Earth; thus their study from extraterrestrial samples may help identify signs of prebiotic chemistry and life on other planets and may reveal how life as we know it began. This study analyzed amino acid concentrations and distributions in 42 CC samples, including returned samples from asteroids Ryugu and Bennu, to investigate the relationship between amino acid composition and parent body processes. We performed a statistical analysis of the amino acid molecular distributions and abundances in the context of meteoritic hydrogen, carbon, nitrogen, and carbonate total contents to explore the links between these organic species and thermal and aqueous processing experienced in the parent bodies. We also evaluated whether meteoritic amino acid ratios can be used as anti-biosignatures, and we re-evaluated the links between l-isovaline enantiomeric excesses and parent body aqueous alteration. While some trends were observed, correlations between amino acid distributions and alteration proxies (H, C, N, carbonates, enantiomeric excess) were generally weak, which indicates the need for larger sample sets. Thermal metamorphism correlated with lower amino acid and elemental [hydrogen (H), carbon (C), and nitrogen (N)] abundances, consistent with diverse parent bodies or localized processing. Ryugu samples exhibited significant amino acid variations despite similar bulk elemental compositions due to parent body heterogeneity. No strong statistical correlations were found between amino acid concentrations and H, C, or N content, which diminishes the reliability of predictions of amino acid abundances based solely on observed elemental abundances. While Ryugu and Bennu may share a common, Ceres-like parent body, observed differences in chemical composition suggest diverse evolutionary pathways. Finally, principal component analysis of amino acid and elemental data revealed distinct groupings that place Ryugu samples in a potentially unique subgroup and Bennu within the C2-ung chondrite group. These findings underscore the need for further study of such materials, especially given our discovery of their distinct nature, and emphasizes the insights gleaned from the ability to analyze returned asteroid samples.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"437-449"},"PeriodicalIF":3.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144186425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial Intelligence-Enhanced Detection of Biogenicity Using Laboratory Specimens of Biologically and Microbially Induced Sedimentary Structures in a Controlled Experiment.","authors":"Florent Arrignon, Liza Alexandra Fernandez, Stéphanie Boulêtreau, Neil S Davies, Jessica Ferriol, Frédéric Julien, Joséphine Leflaive, Thierry Otto, Erwan Roussel, Johannes Steiger, Jean-Pierre Toumazet, Dov Corenblit","doi":"10.1089/ast.2024.0153","DOIUrl":"10.1089/ast.2024.0153","url":null,"abstract":"<p><p>The search for traces of life can be based on the detection of specific signatures produced by microorganisms on sedimentary rocks. Microbially induced sedimentary structures (MISSs) develop under specific physicochemical conditions that are likely to have potentially existed on Mars during the Noachian period. We designed an experiment under controlled laboratory conditions to explore the wide range variability in biogeomorphological responses of clay-sand substrates to the development of biological mats-including microbial mats-of different strains and biomasses, and an abiotic control. A 3D picture dataset based on the experiment was built using multi-image photogrammetry. Visual observations were combined with multivariate statistics on computed topographical variables to interpret the diversity in the resulting biotic and abiotic mud cracks. Finally, an artificial intelligence (AI) classifier based on convolutional neural networks was trained with the data. The resulting model predicted accurately not only the biotic-abiotic differences but also the differences between strains and biomasses of biotic treatments. Its results outperformed the blind human classification, even using only grayscale pictures. Class Activation Maps showed that AI followed several decision paths, not always like those of the human expert. Next steps are proposed for application of these models to <i>ex situ</i> biogeomorphological structures (fossil and modern MISS) on Earth's surface, to ultimately transpose them to a martian context.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"414-436"},"PeriodicalIF":3.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144186424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"UVC-Intense Exoplanets May Not Be Uninhabitable: Evidence from a Desert Lichen.","authors":"Tejinder Singh, Christos D Georgiou, Christopher S Jeffrey, Matthew J Tucker, Casey S Philbin, Tanzil Mahmud, Christopher P McKay, Henry J Sun","doi":"10.1089/ast.2024.0137","DOIUrl":"https://doi.org/10.1089/ast.2024.0137","url":null,"abstract":"<p><p>Many of the recently discovered Earth-like exoplanets are hosted by M and F stars, stars that emit intense UVC, especially during a flare. We studied whether such planets are nevertheless habitable by irradiating a desert lichen, <i>Clavascidium lacinulatum,</i> with 254-nm 55 W/m² UVC nonstop for 3 months in the laboratory. Only 50% of its algal photobiont cells were inactivated. To put this in perspective, we used the same setup to challenge the photobiont cells but grown in pure culture, and <i>Deinococcus radiodurans</i>, the most radiation-resistant bacterium on Earth. Entire monolayers of hundreds of cells were inactivated in just 60 s. Further studies indicated that the cortex of the lichen was rendered UVC-opaque by deposits of phenolic secondary metabolites in its interstices. The lichen was injured only because, while most photochemical reactive oxygen species were quenched, photochemical ozone was not. We conclude that UVC-intense exoplanets are not necessarily uninhabitable to photosynthetic organisms.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 6","pages":"404-413"},"PeriodicalIF":3.5,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144301113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomarker Preservation in Antarctic Sandstones after Prolonged Space Exposure Outside the International Space Station During the ESA EXPOSE-E Lichens and Fungi Experiment.","authors":"Alessia Cassaro, Claudia Pacelli, Giuseppina Fanelli, Mickael Baqué, Alessandro Maturilli, Patrick Leo, Veronica Lelli, Jean-Pierre Paul de Vera, Silvano Onofri, Annmaria Timperio","doi":"10.1089/ast.2024.0068","DOIUrl":"https://doi.org/10.1089/ast.2024.0068","url":null,"abstract":"<p><p>A primary aim of current and future space exploration missions is the detection and identification of chemical and biological indicators of life, namely biomarkers, on Mars. The Mars Sample Return NASA-ESA program will bring to Earth samples of martian soil, acquired from up to 7 cm depth. The ESA Rosalind Franklin rover will search for signs of life in the subsurface (down to a depth of 2 meters), given the highly radioactive conditions on Mars' surface, which are not ideal for life as we know it and for the preservation of its traces. In the frame of the Lichens and Fungi Experiment, small fragments of Antarctic sandstones colonized by cryptoendolithic microbial communities were exposed to space and simulated martian conditions in low Earth orbit for 18 months, aboard the EXPOSE-E payload. Through the use of Raman and infrared spectroscopies, as well as a metabolomic approach, we aimed to detect organic compounds in a quartz mineral matrix. The results show that pigments, such as melanin, carotenoids, and chlorophyll, lipids, and amino acids, maintained their stability within minerals under simulated martian conditions in space, which makes them ideal biomarkers for the exploration of putative life on Mars.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 5","pages":"331-345"},"PeriodicalIF":3.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143967346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strong Evidence that Abiogenesis Is a Rapid Process on Earth Analogs.","authors":"David Kipping","doi":"10.1089/ast.2025.0009","DOIUrl":"https://doi.org/10.1089/ast.2025.0009","url":null,"abstract":"<p><p>The early start to life naively suggests that abiogenesis is a rapid process on Earth-like planets. However, if evolution typically takes ∼4 Gyr to produce intelligent life-forms like us, then the limited lifespan of Earth's biosphere (∼5-6 Gyr) necessitates an early (and possibly highly atypical) start to our emergence-an example of the weak anthropic principle. Our previously proposed objective Bayesian analysis of Earth's chronology culminated in a formula for the minimum odds ratio between the fast and slow abiogenesis scenarios (relative to Earth's lifespan). Timing from microfossils (3.7 Gya) yields 3:1 odds in favor of rapid abiogenesis, whereas evidence from carbon isotopes (4.1 Gya) gives 9:1, both below the canonical threshold of \"strong evidence\" (10:1). However, the recent result of a 4.2 Gya LUCA pushes the odds over the threshold for the first time (nominally 13:1). In fact, the odds ratio is >10:1 for all possible values of the biosphere's ultimate lifespan and speculative hypotheses of ancient civilizations. For the first time, we formally have strong evidence that favors the hypothesis that life rapidly emerges in Earth-like conditions (although such environments may themselves be rare).</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 5","pages":"323-326"},"PeriodicalIF":3.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143956296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman Spectroscopy as a Tool to Measure Silanol as Evidence of Water-Rock Interactions for Astrobiological Exploration.","authors":"Yasumoto Tsukada, Stephen A Bowden","doi":"10.1089/ast.2024.0088","DOIUrl":"https://doi.org/10.1089/ast.2024.0088","url":null,"abstract":"<p><p>Because a range of silica minerals can precipitate from water, the analysis of silica mineral phases is important for astrobiological exploration. In this context, poorly crystalline opaline minerals that contain intracrystalline water are commonly accepted indicators of the presence of water in the geological past. However, opaline minerals are not the only silica phases that are evidence of past interaction with water. Water may become incorporated within crystalline quartz as silanol (Si-OH)-hydroxyl groups present as structural defects within a crystal lattice. Raman spectroscopy is a highly reliable method for detecting mineral composition, and it can also detect silanol. By analyzing Raman spectra from various silica gemstones and rocks, we found that 52 out of 71 quartz samples contain silanol. However, silanol was not universally present across all samples. Microcrystalline quartz and samples in which silica phases had replaced other minerals tended to display the highest levels of silanol, whereas macrocrystalline quartz exhibited the lowest values, as indicated by the Sil_prop parameter. In addition, we observed instances where quartz-hosted silanol and carbonaceous materials were codetected, which suggests the potential for Raman to be used to detect both carbonaceous organic matter and water, and therefore potential indications of both life and habitability.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 5","pages":"346-358"},"PeriodicalIF":3.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143966482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluorescent Biomolecules Detectable in Near-Surface Ice on Europa.","authors":"Gideon Yoffe, Keren Duer-Milner, Tom Andre Nordheim, Itay Halevy, Yohai Kaspi","doi":"10.1089/ast.2024.0140","DOIUrl":"https://doi.org/10.1089/ast.2024.0140","url":null,"abstract":"<p><p>Europa, Jupiter's second Galilean moon, is believed to host a subsurface ocean in contact with a rocky mantle, where hydrothermal activity may drive the synthesis of organic molecules. Among these possible organic molecules, abiotic synthesis of aromatic amino acids is unlikely, so their detection on planetary surfaces such as Europa suggests that they could be considered a potential biosignature. Fluorescence from aromatic amino acids, with characteristic emissions in the 200-400 nm wavelength range, can be induced by a laser and may be detectable where ocean material has been relatively recently emplaced on Europa's surface, as indicated by geologically young terrain and surface features. However, surface bombardment by charged particles from the jovian magnetosphere and solar ultraviolet (UV) radiation degrades organic molecules and limits their longevity. We model radiolysis and photolysis of aromatic amino acids embedded in ice. Our model shows dependencies on hemispheric and latitudinal patterns of charged particle bombardment and ice phase. We demonstrate that such molecules contained within freshly deposited ice in high-latitude regions on the surface of Europa are detectable using laser-induced UV fluorescence, even from an orbiting spacecraft.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 5","pages":"359-366"},"PeriodicalIF":3.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143973455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applied Astrobiology: An Integrated Approach to the Future of Life in Space.","authors":"Robin Wordsworth, Collin Cherubim, Shannon Nangle, Aaron Berliner, Esther Dyson, Peter Girguis, David Grinspoon, Rachel Harris, Ken Liu, Adam Marblestone, Chris Mason, Ryan Morhard, Dimitar D Sasselov, Sara Seager, Robert Wood, Peter Worden","doi":"10.1089/ast.2024.0156","DOIUrl":"https://doi.org/10.1089/ast.2024.0156","url":null,"abstract":"<p><p>Searching for extraterrestrial life and supporting human life in space are traditionally regarded as separate challenges. However, there are significant benefits to an approach that treats them as different aspects of the same essential problem: How can we conceptualize life beyond our home planet?</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":"25 5","pages":"327-330"},"PeriodicalIF":3.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143960016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}