Alexander A Pavlov, Hannah L McLain, Kendra K Farnsworth, Daniel P Glavin, Jamie E Elsila, Jason P Dworkin, Zhidan Zhang, Christopher H House
{"title":"类火星永久冻土条件下氨基酸的缓慢辐射分解:在火星上寻找现存生命的应用。","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":null,"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 H<sub>2</sub>O-ice and silicate matrices and amino acids from dead <i>Escherichia coli</i> microorganisms in H<sub>2</sub>O-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 H<sub>2</sub>O-ice and isolated pure amino acids dissolved in H<sub>2</sub>O-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":2.6000,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"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\":null,\"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 H<sub>2</sub>O-ice and silicate matrices and amino acids from dead <i>Escherichia coli</i> microorganisms in H<sub>2</sub>O-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 H<sub>2</sub>O-ice and isolated pure amino acids dissolved in H<sub>2</sub>O-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\":2.6000,\"publicationDate\":\"2025-09-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Astrobiology\",\"FirstCategoryId\":\"101\",\"ListUrlMain\":\"https://doi.org/10.1177/15311074251366249\",\"RegionNum\":3,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2025/8/11 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q2\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Astrobiology","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1177/15311074251366249","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2025/8/11 0:00:00","PubModel":"Epub","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Slow Radiolysis of Amino Acids in Mars-Like Permafrost Conditions: Applications to the Search for Extant Life on Mars.
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 Escherichia coli 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 E. coli 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.
期刊介绍:
Astrobiology is the most-cited peer-reviewed journal dedicated to the understanding of life''s origin, evolution, and distribution in the universe, with a focus on new findings and discoveries from interplanetary exploration and laboratory research.
Astrobiology coverage includes: Astrophysics; Astropaleontology; Astroplanets; Bioastronomy; Cosmochemistry; Ecogenomics; Exobiology; Extremophiles; Geomicrobiology; Gravitational biology; Life detection technology; Meteoritics; Planetary geoscience; Planetary protection; Prebiotic chemistry; Space exploration technology; Terraforming