Astrobiology最新文献

{"title":"Desorption of Terrestrial Noble Gases in Mars 2020 Sample Tubes: Implications for Mars Sample Return.","authors":"Jeffrey T Osterhout, Kenneth A Farley, Meenakshi Wadhwa, Jonathan Treffkorn","doi":"10.1177/15311074251377647","DOIUrl":"https://doi.org/10.1177/15311074251377647","url":null,"abstract":"<p><p>The Mars Sample Return (MSR) Campaign aims to collect and transport to Earth samples of martian atmosphere contained in sample tubes onboard the Mars 2020 rover, Perseverance. Understanding and mitigating the potential impact of terrestrial noble gas contamination is critical to ensuring the scientific integrity of these samples. This study quantifies the desorption of terrestrial argon (⁴⁰Ar) and xenon (¹²⁹Xe) from the interior of a flight-like Mars 2020 sample tube under high vacuum and provides critical insights into the potential contamination risks for returned martian atmospheric samples. Our results show that desorption rates decrease exponentially with time over ∼19 months and that desorbed terrestrial ⁴⁰Ar and ¹²⁹Xe will contribute less than 0.01% and 0.1%, respectively, to the martian noble gas inventory within a sealed sample tube that consists of martian atmosphere at a pressure of ∼7 mbar. This study suggests that the Mars 2020 sample tubes are suitable for capturing and preserving atmospheric samples from Mars for future scientific investigation.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145091204","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":"From the Biosphere to the Geosphere: Assessing Lipid Biomarker Taphonomy Through a Lithification Gradient.","authors":"Pablo L Finkel, Daniel Carrizo, Victor Parro, Federico A Vignale, María Eugenia Farías, Laura Sánchez-García","doi":"10.1177/15311074251366268","DOIUrl":"10.1177/15311074251366268","url":null,"abstract":"<p><p>The alteration of biomass into simpler molecular remnants is relevant for the search for ancient and extraterrestrial life, where identifying recurrent taphonomic pathways is crucial for the attribution of biogenicity to otherwise nonbiological molecules. This work evaluates the alteration of lipids-recalcitrant biomarkers derived from cell membranes-across a lithification gradient, from a biologically active microbial mat, through a lithifying mat, to a fully lithified microbialite. Lipids from these samples, obtained from the high-altitude, hypersaline lake of Pozo Bravo (Argentinean Andes), were analyzed at molecular and isotopic levels to reconstruct biological sources and assess preservation along a bio-to-geo transition. Lipids from the lithifying mat and microbialite retained molecular features from the soft microbial mat (e.g., cyano- and purple sulfur bacteria), albeit at lower concentrations and diversity. Moreover, our analysis revealed preferential alteration of labile structural features such as unsaturations, methyl-, and pentacyclic structures, which decreased by ≥91% from soft to lithifying mat and ≥68% from lithifying mat to microbialite. Saturated and linear chains were more resistant, decreasing by ≥64% and ≥29%, respectively. These findings highlight how lipid preservation varies during lithification; thus, they provide valuable insights for biogenicity assessments and can help guide future efforts aimed at detecting ancient life.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"611-632"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144940373","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":"Characterizing Microbial Communities in >7000- and >180,000-Year-Old Antarctic Permafrost Using a Low-Biomass Decontamination Protocol.","authors":"Jacob T H Anderson, Alexis J Marshall, Roanna Richards-Babbage, Ian R McDonald, Gary S Wilson, Andrey Abramov, Nikita Demidov, S Craig Cary","doi":"10.1177/15311074251369770","DOIUrl":"10.1177/15311074251369770","url":null,"abstract":"<p><p>The McMurdo Dry Valleys may harbor diverse surface microbial communities, yet little is known about subsurface microorganisms in permafrost and their potential for paleoecological reconstruction. Here, we present microbial diversity and paleoecology from lower Wright Valley (7000- to 25,000-year-old) and Pearse Valley (>180,000-year-old) permafrost habitats in the McMurdo Dry Valleys. Using a new decontamination protocol, low-biomass extraction approaches, and 16S ribosomal RNA gene amplification sequencing, we assessed microbial community structure and diversity. The difference between surface and subsurface microbial communities at both lower Wright and Pearse valleys suggests the environmental conditions were different at the time of colonization. Microbial taxa identified in subsurface permafrost but not in the surface soil in both valleys indicate an ancient and isolated microbial community. In contrast, communities were not resolved at a high-elevation site in the stable upland zone, the Friis Hills (>6 Ma). The inability to identify DNA using amplicon sequencing in the Friis Hills is consistent with previous efforts to analyze high-elevation soils and permafrost, which suggests that microbial habitability is severely restricted in persistent cold, arid habitats. Therefore, utilizing other approaches may be necessary to analyze surface and subsurface permafrost on Earth, and perhaps Mars, where low-abundance microbial populations may be present.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"633-647"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144940352","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":"Inverse Relationship Between Halophilic Growth and Cell Integrity Under Extremely Chaotropic Conditions.","authors":"Luke A Fisher, Alyson R Bovee, Jordan M McKaig, Benjamin Klempay, Alexandra Pontefract, Christopher E Carr, Britney E Schmidt, Jeff S Bowman, Douglas H Bartlett","doi":"10.1177/15311074251376365","DOIUrl":"10.1177/15311074251376365","url":null,"abstract":"<p><p>Concentrated magnesium chloride brines are extreme environments that are inhospitable to life on Earth. The ionic strength of these brines significantly depresses water activity and concomitantly exerts significant chaotropic stress. Although these brines are largely considered sterile, the well-known preservative effects of magnesium chloride on certain biomolecules, such as DNA, confound life detection approaches and efforts to constrain precisely the habitable window of life on Earth. While the ability of these brines to preserve genetic material is well documented, the preservation of whole cells, which are generally thought to be preserved in magnesium chloride brines, is poorly described. This work explores the effects of long-term exposure of highly chaotropic magnesium chloride on viability, cell integrity, and DNA preservation in the model organisms <i>Escherichia coli</i>, <i>Salinibacter ruber</i>, <i>Halobacterium salinarum</i>, and <i>Haloquadratum walsbyi</i>. The selected halophiles are relevant for this study as they are abundant and globally distributed in brine environments, while <i>E. coli</i> was chosen to represent infall or transport of non-adapted cells. We observed unexpected resilience in <i>E. coli</i>, which survived in 4 M magnesium chloride for longer than the tested halophiles, and nonviable cells maintained structural whole-cell integrity for over 3 years. Whole <i>S. ruber</i> cells were also preserved in 4 M magnesium chloride, while the tested haloarchaea lost viability and completely degraded within hours of exposure. DNA from all tested strains was recovered from incubations after upwards of 3 years of exposure; it showed some signs of degradation but was nonetheless still amplifiable via polymerase chain reaction. Our work demonstrates that the preservation of whole cells in magnesium chloride brines is not universal. Considering the potential abundance of chaotropic brine environments within our solar system, understanding the limits of life and the preservation of biosignatures in these brines is critical to inform future life detection missions on Earth and beyond.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"648-663"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005844","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":"Slow Radiolysis of Amino Acids in Mars-Like Permafrost Conditions: Applications to the Search for Extant Life on Mars.","authors":"Alexander A Pavlov, Hannah L McLain, Kendra K Farnsworth, Daniel P Glavin, Jamie E Elsila, Jason P Dworkin, Zhidan Zhang, Christopher H House","doi":"10.1177/15311074251366249","DOIUrl":"10.1177/15311074251366249","url":null,"abstract":"<p><p>Future missions dedicated to the search for extant life on Mars will require a clear understanding of the organic biosignature degradation processes in the shallow icy subsurface. Galactic and solar cosmic rays constantly bombard the martian surface and transform and degrade organic biomolecules over time, eventually destroying chemical evidence of life. We conducted radiolysis experiments by exposing individual amino acids in H₂O-ice and silicate matrices and amino acids from dead <i>Escherichia coli</i> microorganisms in H₂O-ice to gamma radiation as a proxy for cosmic ray exposure on the martian surface. The rates of amino acid radiolytic degradation were determined. We found that amino acids in the surface ice on Mars would survive over 50 million years of cosmic ray exposure, which is far greater than the expected age of the current surface ice deposits on Mars. Amino acids from dead <i>E. coli</i> organic matter in H₂O-ice and isolated pure amino acids dissolved in H₂O-ice tend to degrade at similar rates. We found that amino acid radiolytic degradation rates increased with increasing ice temperature in both abiotic and biological amino acids. Montmorillonite did not provide additional protection against gamma radiation to amino acids. Based on our experiments, locations with pure ice or ice-dominated permafrost would be the best places to look for recently deposited amino acids on Mars and, thus, should be considered as a target sampling location for future Mars missions searching for extant life.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"601-610"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820451","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":"From Polymerization-Enabled Folding and Assembly to Chemical Evolution: Key Processes for Emergence of Functional Polymers in the Origin of Life.","authors":"Rotem Edri, Manesh Prakash Joshi, Moran Frenkel-Pinter, Nicholas V Hud, Christine D Keating, Luke J Leman","doi":"10.1177/15311074251365943","DOIUrl":"https://doi.org/10.1177/15311074251365943","url":null,"abstract":"<p><p>Chemical and geological processes on prebiotic Earth are believed to have resulted in the emergence of life through the increasing organization and functionality of organic molecules. This primer provides an overview of some key abiotic chemical and physical processes that could have contributed to life's building blocks (amino acids, nucleotides, fatty acids, and monosaccharides) becoming more ordered during the early stages in the origin of life. The processes considered include polymerization, intramolecular folding, multimolecular assembly, and chemical evolution through various selective mechanisms. Our goal is to provide an accessible, high-level synopsis of these key general concepts for a diverse audience.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144940289","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 Existing Frameworks of Delivery of Major Volatiles and the Feasibility of Mars-Mass Planetary Embryos as the Major Volatile Contributors to Bulk Silicate Earth.","authors":"Debjeet Pathak, Rajdeep Dasgupta","doi":"10.1177/15311074251365197","DOIUrl":"10.1177/15311074251365197","url":null,"abstract":"<p><p>The presence of major volatile elements-carbon, hydrogen, nitrogen, and sulfur-on Earth is critical for establishing life. The origin of these life-essential volatile elements (LEVEs) on Earth has been studied for many years. Here, we present a brief compilation of the prevailing ideas regarding volatile delivery to Earth and evaluate their origins, strengths, and weaknesses. Motivated by the fact that one model of LEVE delivery is via a giant impactor to Earth, we subsequently present a geochemical model aimed at understanding the possible volatile inventory and fractionation between the core, the silicate magma ocean (MO), and the atmosphere of a Mars-mass embryo. We looked at various end-member accretion scenarios of the embryo and their influence on the embryo's LEVE budget and the LEVE ratios. We varied various chemical (initial concentration of volatiles in the undifferentiated bodies and the oxygen fugacity [<i>f</i>O₂] of geochemical fractionation) and physical parameters (silicate-mass fraction of the accreting bodies, MO depth) to observe their effects on the absolute and relative LEVE budgets of the embryo. Our results show that an oxidizing condition (log<i>f</i> O₂ ≥ IW-1 [Iron-Wüstite]) is critical in establishing the relative LEVE budget of the embryo's MO, closer to that of present-day bulk silicate Earth. Furthermore, the accretion of larger bodies to form the Mars-mass embryo results in the closest match of the LEVE ratios to that of the present-day bulk silicate Earth (BSE). However, the absolute LEVE budget of the MO of Mars-mass embryo is depleted by at least 1-2 orders of magnitude compared with the BSE under all model calculation scenarios. In contrast, the CI-chondrite-normalized LEVE budget of the embryos's core, in many of the scenarios, especially from the reduced (<i>e.g.,</i> IW-2) bodies, overlaps or exceeds the present-day BSE estimate. We argue that for a Mars-mass, differentiated embryo, the cores provide a better prospect for LEVE delivery to proto-Earth, through core breakups and subsequent mixing in the MO or solid mantle. Future studies need to better assess whether the fractional retention of core materials in the silicate reservoir can match the present-day BSE LEVE budgets and how such a process compares with the LEVE delivery via less-processed primitive asteroids.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144871177","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":"Experimental Models on the Prebiotic Formation of Biopolymer Building Blocks.","authors":"César Menor-Salván, Marta Ruiz-Bermejo","doi":"10.1177/15311074251365950","DOIUrl":"https://doi.org/10.1177/15311074251365950","url":null,"abstract":"<p><p>The scientific study of the origins of life is a deep pursuit that exists at the intersection of multiple disciplines. Prebiotic chemistry focuses on understanding how biopolymer building blocks such as amino acids, nucleotides, and sugars emerged and how their chemical and structural space evolves toward life (chemical evolution). Simulation experiments have been essential for exploring plausible pathways for the origin of building blocks under early Earth conditions and planetary environments. Key examples include the seminal Miller-Urey experiment and the polymerization of hydrogen cyanide. Research highlights the role of environmental cycles and geochemistry in shaping the prebiotic chemical space. These processes facilitated the condensation and stabilization of biopolymer precursors, particularly in terrestrial or small-pond scenarios. Noncanonical building blocks, including triazines and alternative amino acids, may have contributed to proto-biopolymer formation. This expands our understanding of chemical evolution. Despite significant progress, challenges remain, particularly in understanding nucleoside formation and the transition to modern biopolymers. This review provides a general overview of the prebiotic formation of biopolymer building blocks and examines both classic and seminal experiments and recent experimental approaches. Insights provided by extraterrestrial samples, such as carbonaceous meteorites and asteroids, also contribute to offering a comprehensive perspective on abiogenesis.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144820449","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":"Laminae as Potential Biosignatures.","authors":"Jon Lima-Zaloumis, Sherry L Cady, Jen G Blank, Svetlana Shkolyar, Victor Akudoro, Stanley M Awramik, Barbara Cavalazzi, Keyron Hickman-Lewis, Martin Homann, Nora Noffke, Scott M Perl, Sally L Potter-McIntyre, Frances Westall","doi":"10.1089/ast.2025.0012","DOIUrl":"10.1089/ast.2025.0012","url":null,"abstract":"<p><p>Laminae are millimeter-scale features in rocks created by physiochemical processes that can be influenced by the presence and activities of communities of organisms that occur as biofilms and microbial mats. The structure and composition of laminae reflect the processes involved in their formation and can be preserved in the rock record over geologic time; however, diagenetic and metamorphic alteration can lead to the loss of primary information and confusion over the interpretation of their origins. As potential records of ancient life, laminae can preserve evidence of microbial activity over billions of years of Earth's history. On planetary bodies such as Mars, laminae in sedimentary rocks are common and represent significant features of interest that can record habitable conditions (e.g., the presence of liquid water) at the time of their formation. Here we review the significance of laminae as targets for astrobiological exploration. We discuss common mechanisms by which laminae form in natural environments on Earth, present arguments and evidence for laminae as potential biosignatures, and describe how such information is presented in the NASA Life Detection Knowledge Base.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"501-524"},"PeriodicalIF":2.6,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144625317","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":"Stable Isotope Abundance Patterns as Potential Biosignatures.","authors":"David J Des Marais, Tristan Caro, Rajani Dhingra, Allison C Fox, Toni Galloway, Tyler J Mackey, Jeffrey Osterhout, M Joseph Pasterski, Bethany P Theiling","doi":"10.1177/15311074251360977","DOIUrl":"10.1177/15311074251360977","url":null,"abstract":"<p><p>The abundance and distribution of stable isotopes of an element in a substance can provide insights regarding the source, synthesis, and environmental history of that substance. Because isotopic discrimination during chemical reactions can be unique to specific chemical pathways or environmental conditions, isotopic patterns within a substance or between related substances may provide insights into their formation. Biosynthetic pathways can create isotopic patterns that differ from patterns that arise from abiotic processes, but this is not universally true. Isotope patterns are signatures of chemical reactions, so they require additional context to be used as biosignatures. The framework of the Life Detection Knowledge Base discussed herein is used to convey arguments that support or challenge the utility of isotopic patterns for life detection. Examples of carbon and sulfur isotopic patterns in organic materials and minerals are presented to indicate how the life detection criteria \"prevalence\" and \"signal strength\" can be applied. In future work, more abiotic processes that might create false-positive life detection claims must be characterized. A broader range of microbial communities, taxa, and biomolecules should be explored for isotopic patterns. Additional elements also warrant investigation as potential isotopic biosignatures and environmental indicators. Studies of sedimentary macromolecular organic matter should be expanded further to provide deeper insights into isotopic abundance patterns.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":" ","pages":"537-549"},"PeriodicalIF":2.6,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144788163","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}