Astrobiology最新文献

{"title":"Assessing the Preservation of Polysaccharides from a Sea-Ice Bacterium Through Analog Icy Moon Plume Ejection.","authors":"Georges Kanaan, Megan Stull, Alexandria Aspin, Mariam Naseem, Ziming Yang, Marc Neveu","doi":"10.1177/15311074261494441","DOIUrl":"https://doi.org/10.1177/15311074261494441","url":null,"abstract":"<p><p>Detection of complex organics emitted from Saturn's moon Enceladus has intensified the search for biosignatures accessible to future missions. Extracellular polysaccharides (EPSs) from sea-ice bacteria such as <i>Colwellia psychrerythraea</i> are promising analogs for potential biosignatures due to their prevalence in cold, saline environments analogous to the subsurface oceans on icy worlds. Here, we investigate experimentally the effect of a direct transition from liquid to vacuum environments on the detectability and composition of EPSs from <i>C. psychrerythraea</i> 34H using gas chromatography-mass spectrometry. EPSs from the bacterium were isolated and resuspended in solutions prepared with 1 wt. % NaCl and pH 9 to match properties inferred from enceladan plume grains. The primary monomers detected, including fatty acid methyl esters and sugars such as glucuronic acid, galacturonic acid, and glucosamine, remained detectable after injection into the vacuum, with slight shifts in relative abundances. These findings support the potential for EPS detection in icy moon plume samples. Our analytical approach is comparable to that of gas chromatograph-mass spectrometer payloads planned for the exploration of Enceladus and Europa, which aim to characterize organic material in plume or surface ice. These findings highlight microbial EPSs as potentially viable biosignature candidates and inform the interpretation of future <i>in situ</i> organic detections on ocean worlds.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"15311074261494441"},"PeriodicalIF":2.3,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149126460","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":"Beyond the Prebiotic Soup: Solid Organic Films and Protocell-Like Formation in Prebiotic Discharge Experiments.","authors":"Christian Jenewein, Fernando Rull-Perez, Marco Veneranda, Juan Manuel García-Ruiz","doi":"10.1177/15311074261493395","DOIUrl":"https://doi.org/10.1177/15311074261493395","url":null,"abstract":"<p><p>The original Miller-Urey experiment demonstrated the abiotic synthesis of organic compounds under early Earth conditions, yet the physicochemical properties and internal organization of the associated insoluble solid organic films (SOFs) remain poorly constrained. Here we present a spatially resolved characterization of SOFs formed in prebiotic discharge experiments, focusing on their chemical heterogeneity, structural organization, and role in the emergence of hollow organic biomorphs. Using a combination of electron microscopy and spectroscopic techniques, we show that the insoluble SOF is a continuous but chemically heterogeneous matrix whose molecular composition varies systematically across the reactor as a function of local gas-liquid-solid interactions. Distinct regions of the SOF are enriched in aliphatic amine-rich polymers, aromatic carbon domains, cyanide-derived intermediates, and amorphous carbon, indicating that hydrogen cyanide (HCN)-derived chemistry evolves differently within specific microenvironments rather than proceeding uniformly throughout the system. We further demonstrate that spherical, caterpillar-like, and polyp-like hollow biomorphs preferentially emerge at hydrated interfacial regions of the SOF, thereby directly linking their morphogenesis to spatial chemical heterogeneity and phase-boundary chemistry in spark-driven systems. The SOF's capacity to shield chemically fragile solutes and emerging biopolymers through near-ultraviolet chromophore absorption, combined with its abiotic compartmentalization properties, suggests a potentially important role in abiogenesis.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"15311074261493395"},"PeriodicalIF":2.3,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149126442","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":"Oxidation of Photochemical Organic Hazes: A Prebiotic Source of Oxygen-Bearing Organics in Titan's Atmosphere and Early Earth?","authors":"Louis Maratrat, Maëva Millan, Valentin Moulay, Ludovic Vettier, Alex Abello, Caroline Freissinet, Nathalie Carrasco","doi":"10.1177/15311074261493349","DOIUrl":"https://doi.org/10.1177/15311074261493349","url":null,"abstract":"<p><p>Photochemical organic hazes such as those found in the atmosphere of Titan, the largest satellite of Saturn, are mainly composed of reduced chemical components. However, in these predominantly reduced atmospheres favorable to the formation of hazes, oxidized species can be produced transiently by one-off events such as surface impacts or via episodic outgassing of water ice particles. Due to their native reduced composition, organic hazes may interact with these oxidative species. This mechanism thus appears as a potential source of oxidized organics in Titan and more generally in hazy planetary atmospheres. To investigate the reactivity of reduced organic photochemical hazes, Titan's aerosol laboratory analogs (or Titan's tholins) have been chosen as a proxy. Two types of tholins were synthetized and systematically compared using gas chromatography coupled with mass spectrometry: a tholin sample exposed to air and an air-preserved tholin sample. This approach allowed us to identify several oxygen-bearing species, mainly urea, oxalic acid, hydroxy-amino-1,3,5-triazine, and carboxylic acids. Mechanisms that explain the formation of these latter oxidized organics were proposed. Possible precursors for urea, oxalic acid, and hydroxy-amino-1,3,5-triazine were identified. These results provide new input in the discussion of the existence of heterogeneous oxidation of photochemical hazes in planetary atmospheres. Two cases are developed here: Titan and Hadean early Earth. In these two contexts, oxidation of photochemical hazes could have provided prebiotic matter as oxidized organics.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"15311074261493349"},"PeriodicalIF":2.3,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149103418","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":"Atmospheres as Habitats.","authors":"Noam R Izenberg, Diana M Gentry, Rakesh Mogul, Kevin McGouldrick, Paul A Burke, Paul K Byrne, Stephen R Kane, Tom A Nordheim, Kevin B Stevenson, Michael J Way, Thomas D Curtis","doi":"10.1177/15311074261475054","DOIUrl":"10.1177/15311074261475054","url":null,"abstract":"<p><p>The potential of planetary atmospheres as habitats is understudied and likely underestimated. Although planetary atmospheres can provide the fundamental physical, chemical, and energetic requirements for life, they also represent unique challenges to survival and biosphere stability. Atmospheric habitats, either self-contained or dependent on surface biospheres, may exist elsewhere in the solar system and on exoplanets. Four hypotheses essential to airborne habitats and their potential importance to astrobiology include: H-I: Earth can host fully airborne life. H-II: Fully airborne microbial life can be experimentally evolved and sustained in the laboratory. H-III: Atmospheres within our solar system can be assessed for a potential aerobiosphere, with Venus the most likely candidate. H-IV: Atmospheres around exoplanets can be modeled, simulated, and observed to assess the likelihood of aerobiospheres. New theory, modeling, observation, and experimentation are required to improve our understanding of the constraints and likelihood of airborne life. Notably, we can neither confirm nor rule out multigenerational airborne life on Earth yet.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"916-922"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148673002","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":"Astrobiological Implications of Lava Flows Superposed on Martian Glaciers: Assessment of Formation and Fate of Meltwater, Moulin Formation, Induced Transition to Wet-Based Glacial Conditions, and Ice-Flow Velocity Enhancements.","authors":"James L Fastook, James W Head","doi":"10.1177/15311074261446502","DOIUrl":"10.1177/15311074261446502","url":null,"abstract":"<p><p>Volcanic eruptions and glacial ice have occurred at virtually all latitudes and altitudes throughout Mars history. To assess the astrobiological potential of processes and microenvironments associated with lava flows onto glacial ice, we explore: (1) the influence of lava flow loading on the flow behavior of underlying ice, (2) whether, and for how long, wet-based conditions might occur and be sustained in otherwise cold-based glacial environments, and (3) the immediate fate of the meltwater generated, whether moulins can be generated, and whether and for how long wet-based conditions are generated by such processes. We employ a 1D time-dependent solution of the heat-flow equation to solve for the transient temperature field within a column of ice subjected to instantaneous deposition of a hot lava layer, exploring the parameter space by examining six different initial surface temperatures and three potential geothermal fluxes to characterize a range of past climates/geological regimes. We observe an <i>initial pulse</i> of accelerated flow due to the increased loading by the lava and consequent increase in the driving stress. A <i>secondary pulse</i> of acceleration occurs as the temperature wave from the lava penetrates the ice and reaches the bed, where the bulk of the deformation occurs in response to the warmer, softer ice. We observe basal melting as the bed briefly reaches the melting point and characterize the amounts of water produced during such brief basal melting intervals. Examination of the meltwater generated below, and in moats adjacent to the superposed lava, shows that completely full moats can propagate cracks through km-thick ice, and such crevasses can remain open (moulins) if they are at least 90% full. The greatest volume of drained water is produced by thin lava over thick ice, but the longest duration draining events occur for moderate lava thicknesses over thinner ice. Locally wet-based glacial conditions could persist below the superposed lava flow for durations well over ∼10³ years. We explore the detailed consequences of lava flow/ice interaction, highlighting those most important for the formation and dispersal of potential cryophilic microbiota on Mars, opening new windows of Mars history for astrobiological research and exploration.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"811-833"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760797","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":"Carbon and Sulfur Isotopes of Microfossils and Pyrites from Neoarchean Cherts: Microbial Diversity in an Ancient Deep-Marine Environment.","authors":"Jeffrey T Osterhout, Andrew D Czaja, Kenneth H Williford, Kouki Kitajima","doi":"10.1177/15311074261485886","DOIUrl":"10.1177/15311074261485886","url":null,"abstract":"<p><p>The 2.52 Ga Gamohaan Formation in South Africa offers critical insights into microbial ecosystems that inhabited deep-marine environments during the late Archean. Large spheroidal microfossils and pyrite grains preserved in finely laminated black cherts reveal evidence of diverse metabolic processes and a complex deep-marine sulfur cycle. This study combines optical microscopy, scanning electron microscopy, and Raman spectroscopy to characterize fossil kerogen and sedimentary pyrites, along with secondary ion mass spectrometry to analyze their <i>in situ</i> carbon (δ¹³C) and sulfur (δ³⁴S) isotope compositions, respectively. Raman spectroscopy established the kerogenous composition and thermal maturity of the microfossils. <i>In situ</i> δ¹³C_org values (-41.3‰ to -32.2‰) are lower on average than bulk organic matter and define two statistically distinct δ¹³C_org populations, with large spheroidal fossils exhibiting systematically lower values than small spheroids. This size-correlated pattern is consistent with differences in carbon sources, fixation pathways, or ecological setting. Secondary ion mass spectrometry δ³⁴S analyses of pyrite grains (-0.7‰ to +6.3‰) show variability corresponding to differences among pyrite morphologies, consistent with microbial sulfate reduction and further sulfur cycling under sulfate-limited conditions in this deep-marine environment. These isotope data provide an independent geochemical framework for evaluating sulfur-based chemotrophic interpretations of the microfossil assemblage. Collectively, the carbon and sulfur isotope signatures support the presence of a complex benthic sulfur cycle and highlight the ecological and metabolic complexity of offshore marine ecosystems in the Neoarchean.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"851-867"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148890809","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":"Signatures of Silicification in Lava Tubes: Implications for Biosignature Preservation and Detection on Earth and Mars.","authors":"Dina M Bower, Maëva Millan, Mathilde Mussetta, Clara Christiann, Amy C McAdam, Christine A Knudson, Jamielyn Jarvis, Cherie N Achilles, Jacob Richardson, Patrick L Whelley, Conor A Nixon, Mary N Parenteau","doi":"10.1177/15311074261484811","DOIUrl":"10.1177/15311074261484811","url":null,"abstract":"<p><p>Terrestrial lava tubes serve as analogs for potentially habitable subsurface environments on Mars due to the bioenergetic potential of basalts, formation of secondary minerals, presence of actively seeping fluids, and isolation from the surface. On Earth, a wide variety of microbial communities that thrive in lava tubes often leave behind detectable traces of their presence and activity. To further an understanding of the contribution that secondary minerals, such as amorphous silica, can make to the preservation of organic material in lava tubes, we analyzed a small set of silica-rich basaltic lava tube samples from Mauna Loa, Hawai'i, and Lava Beds National Monument, CA. We applied techniques relevant to current Mars missions (Raman spectroscopy, powder X-ray diffractometry, gas chromatograph-mass spectrometry, scanning electron microscopy, and energy-dispersive X-ray spectrometry) and compared our datasets with those collected previously from similar analyses of siliceous sinter deposits from Yellowstone National Park. Despite variations in major elemental and organic compositions, distributions, and concentrations, we did not observe differences in the Raman spectroscopy and X-ray diffractometer data of the different silica-rich samples. Organic molecules were detected by Raman spectroscopy in all samples with varying degrees of specificity, regardless of the presence of morphological evidence of microbes or apparent degree of silicification. Pyrolysis and thermochemolysis gas chromatograph-mass spectrometry analysis also revealed the presence of numerous organic fragments that were likely derived from the remains of microbial communities in the lava tube samples. Where microbial material was observed, there were often overlapping spectra in some of the biomolecular and amorphous silica Raman signatures, which required careful interpretation that included scanning electron microscopy and gas chromatograph-mass spectrometry. Our data indicate that amorphous silica formation in lava tubes can obscure over time the distinctive morphological characteristics of microbial remains, though the chemical signatures of biomolecular compounds can still be detectable. Our findings have implications for the types of instrument packages that could be selected to assess the chemical makeup and textures of silica-rich lava tube deposits and suggest that more targeted studies are warranted to understand the possible implications for biosignature preservation and detection in such environments.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"834-850"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148863532","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":"Habitability and Biosignatures on Earth and Mars.","authors":"Jeffrey T Osterhout, Jonathan Lima-Zaloumis, Ashley Manning-Berg, Marisol Juarez Rivera, Andrea Corpolongo","doi":"10.1177/15311074261485884","DOIUrl":"10.1177/15311074261485884","url":null,"abstract":"","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"791-793"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148872943","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":"The Search for Life and Biosignatures on Mars: A Mars System Science Approach (Atmosphere, Hydrosphere, Cryosphere, Lithosphere, Geologic History).","authors":"James W Head, Robin D Wordsworth, James L Fastook","doi":"10.1177/15311074261470203","DOIUrl":"10.1177/15311074261470203","url":null,"abstract":"<p><p>The most important quest in Mars exploration is the search for biosignatures. We adopt a Mars System Science approach, calling on information from the atmosphere, hydrosphere, cryosphere, lithosphere, and geologic history for an integrated organizational framework of inquiry. We \"follow the water\" by focusing on the characteristics of the hydrological system/cycle, their individual component water reservoirs, and their relationships and interconnectedness through time. We examine the ancillary hydrological cycle environments/processes (fluvial, lacustrine, glacial, cryospheric, groundwater) required for a robust, vertically integrated hydrological cycle to support long-duration northern lowlands oceans, arguably the largest proposed water reservoirs in Mars' history. We find that northern lowlands marine environments are likely to be low volume, transient, and short lived, prior to freezing and sublimation. Temporally associated hydrological system components (e.g., valley networks, lakes) are generally poorly integrated and characterized by intermittent, short-duration wet periods. This highly abbreviated hydrological cycle is likely to be not vertically integrated but instead horizontally stratified and thus potentially characterized by a global cryosphere separating the surface from a deeper, subsurface geothermally warmed groundwater system. Evidence for a horizontally stratified hydrological system can be traced back in time to the Late Noachian. The observed high erosion rates and the presence of phyllosilicates in the Early/Middle Noachian may have been predominantly due to the effects of the three most recent large impact basins, Hellas, Isidis, and Argyre, and their accompanying transient global deluges of hot, torrential rainfall. Sub-cryospheric, long-duration (over 4 billion years), warm subsurface groundwater systems and related chemical reactions provide an environment favorable to troglodytic chemotrophic biota in a globally connected martian \"deep biosphere.\" If life developed on Mars, catastrophic release and dispersal of subsurface groundwater and impact excavation mean that biosignatures are likely to have been introduced and preserved globally. Samples of sedimentary environments returned to Earth may therefore offer a robust test of whether Mars ever possessed life.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"868-915"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148668273","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":"The Possible Aqueous Origins of Manganese Alteration Minerals in the Máaz Formation of Jezero Crater.","authors":"Kimberly P Sinclair, Benton C Clark, Michael W M Jones, David C Catling, William T Elam, Yang Liu","doi":"10.1177/15311074261461401","DOIUrl":"10.1177/15311074261461401","url":null,"abstract":"<p><p>Home to a lake around 4 billion years ago, Jezero Crater is a unique location to study the interplay between igneous processes and aqueous alteration on ancient Mars. The Máaz formation, rich in basaltic rock, is the highest stratigraphic unit on the crater floor and hosts a diversity of alteration phases that indicate multiple aqueous episodes affected the crater floor rocks. Using data from the Planetary Instrument for X-ray Lithochemistry aboard the Perseverance rover, we investigated manganese enrichments across the crater floor. We report on multiple distinct types of Mn-rich materials. The first, in the Guillaumes abrasion low in the Máaz formation, has been tentatively identified as the rare mineral despujolsite (Ca₃Mn⁴⁺(SO₄)₂(OH)₆·3H₂O), which forms on Earth in hydrothermal and lacustrine deposits. In the Alfalfa abrasion patch, high in the Máaz formation, we find Mn-enriched magnetite spatially associated with a Ca-dominant sulfate that may contain minor Mn, which suggests a history of serpentinization followed by exposure to oxidizing acidic fluids. These findings underscore the complexity of aqueous alteration over the course of Jezero history. Future sample return missions could refine mineralogical interpretations and provide more information to improve our understanding of aqueous conditions and habitability in the crater.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"794-810"},"PeriodicalIF":2.3,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148343796","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}