Astrobiology最新文献

{"title":"Linear Ion Trap Mass Spectrometer (LITMS) Instrument Field and Laboratory Tests as Part of the ARADS Field Campaigns.","authors":"Marco E Castillo, Andrej Grubisic, Samuel Larson, Desmond Kaplan, Ryan M Danell, Friso H W van Amerom, Xiang Li, William B Brinckerhoff, Brian J Glass","doi":"10.1089/ast.2023.0039","DOIUrl":"10.1089/ast.2023.0039","url":null,"abstract":"<p><p>The highly compact Linear Ion Trap Mass Spectrometer (LITMS), developed at NASA Goddard Space Flight Center, combines Mars-ambient laser desorption-mass spectrometry (LD-MS) and pyrolysis-gas chromatography-mass spectrometry (GC-MS) through a single, miniaturized linear ion trap mass analyzer. The LITMS instrument is based on the Mars Organic Molecule Analyser (MOMA) investigation developed for the European Space Agency's ExoMars Rover Mission with further enhanced analytical features such as dual polarity ion detection and a dual frequency RF (radio frequency) power supply allowing for an increased mass range. The LITMS brassboard prototype underwent an extensive repackaging effort to produce a highly compact system for terrestrial field testing, allowing for molecular sample analysis in rugged planetary analog environments outside the laboratory. The LITMS instrument was successfully field tested in the Mars analog environment of the Atacama Desert in 2019 as part of the Atacama Rover Astrobiology Drilling Studies (ARADS) project, providing the first <i>in situ</i> planetary analog analysis for a high-fidelity, flight-like ion trap mass spectrometer. LITMS continued to serve as a laboratory tool for continued analysis of natural Atacama samples provided by the subsequent 2019 ARADS final field campaign.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138796046","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":"Field-Based Planetary Protection Operations for Melt Probes: Validation of Clean Access into the Blood Falls, Antarctica, Englacial Ecosystem.","authors":"J A Mikucki, C G Schuler, I Digel, J Kowalski, M J Tuttle, M Chua, R Davis, A M Purcell, D Ghosh, G Francke, M Feldmann, C Espe, D Heinen, B Dachwald, J Clemens, W B Lyons, S Tulaczyk","doi":"10.1089/ast.2021.0102","DOIUrl":"10.1089/ast.2021.0102","url":null,"abstract":"<p><p>Subglacial environments on Earth offer important analogs to Ocean World targets in our solar system. These unique microbial ecosystems remain understudied due to the challenges of access through thick glacial ice (tens to hundreds of meters). Additionally, sub-ice collections must be conducted in a clean manner to ensure sample integrity for downstream microbiological and geochemical analyses. We describe the field-based cleaning of a melt probe that was used to collect brine samples from within a glacier conduit at Blood Falls, Antarctica, for geomicrobiological studies. We used a thermoelectric melting probe called the IceMole that was designed to be minimally invasive in that the logistical requirements in support of drilling operations were small and the probe could be cleaned, even in a remote field setting, so as to minimize potential contamination. In our study, the exterior bioburden on the IceMole was reduced to levels measured in most clean rooms, and below that of the ice surrounding our sampling target. Potential microbial contaminants were identified during the cleaning process; however, very few were detected in the final englacial sample collected with the IceMole and were present in extremely low abundances (∼0.063% of 16S rRNA gene amplicon sequences). This cleaning protocol can help minimize contamination when working in remote field locations, support microbiological sampling of terrestrial subglacial environments using melting probes, and help inform planetary protection challenges for Ocean World analog mission concepts.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92152569","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 Call for a New Definition of Biosignature.","authors":"Catherine Gillen, Cyrille Jeancolas, Sean McMahon, Peter Vickers","doi":"10.1089/ast.2023.0010","DOIUrl":"10.1089/ast.2023.0010","url":null,"abstract":"<p><p>The term <i>biosignature</i> has become increasingly prevalent in astrobiology literature as our ability to search for life advances. Although this term has been useful to the community, its definition is not settled. Existing definitions conflict sharply over the balance of evidence needed to establish a biosignature, which leads to misunderstanding and confusion about what is being claimed when biosignatures are purportedly detected. To resolve this, we offer a new definition of a biosignature as <i>any phenomenon for which biological processes are a known possible explanation and whose potential abiotic causes have been reasonably explored and ruled out.</i> This definition is strong enough to do the work required of it in multiple contexts-from the search for life on Mars to exoplanet spectroscopy-where the quality and indeed quantity of obtainable evidence is markedly different. Moreover, it addresses the pernicious problem of unconceived abiotic mimics that is central to biosignature research. We show that the new definition yields intuitively satisfying judgments when applied to historical biosignature claims. We also reaffirm the importance of multidisciplinary work on abiotic mimics to narrow the gap between the detection of a biosignature and a confirmed discovery of life.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41189651","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":"False Positives and the Challenge of Testing the Alien Hypothesis.","authors":"Searra Foote, Pritvik Sinhadc, Cole Mathis, Sara Imari Walker","doi":"10.1089/ast.2023.0005","DOIUrl":"10.1089/ast.2023.0005","url":null,"abstract":"<p><p>The origin of life and the detection of alien life have historically been treated as separate scientific research problems. However, they are not strictly independent. Here, we discuss the need for a better integration of the sciences of life detection and origins of life. Framing these dual problems within the formalism of Bayesian hypothesis testing, we demonstrate via simple examples how high confidence in life detection claims require either (1) a strong prior hypothesis about the existence of life in a particular alien environment, or conversely, (2) signatures of life that are not susceptible to false positives. As a case study, we discuss the role of priors and hypothesis testing in recent results reporting potential detection of life in the venusian atmosphere and in the icy plumes of Enceladus. While many current leading biosignature candidates are subject to false positives because they are not definitive of life, our analyses demonstrate why it is necessary to shift focus to candidate signatures that are definitive. This indicates a necessity to develop methods that lack substantial false positives, by using observables for life that rely on prior hypotheses with strong theoretical and empirical support in identifying defining features of life. Abstract theories developed in pursuit of understanding universal features of life are more likely to be definitive and to apply to life-as-we-don't-know-it. We discuss Molecular Assembly theory as an example of such an observable which is applicable to life detection within the solar system. In the absence of alien examples these are best validated in origin of life experiments, substantiating the need for better integration between origins of life and biosignature science research communities. This leads to a conclusion that extraordinary claims in astrobiology (<i>e.g.,</i> definitive detection of alien life) require extraordinary explanations, whereas the evidence itself could be quite ordinary.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92152568","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":"Confidence of Life Detection: The Problem of Unconceived Alternatives.","authors":"Peter Vickers, Christopher Cowie, Steven J Dick, Catherine Gillen, Cyrille Jeancolas, Lynn J Rothschild, Sean McMahon","doi":"10.1089/ast.2022.0084","DOIUrl":"10.1089/ast.2022.0084","url":null,"abstract":"Potential biosignatures that offer the promise of extraterrestrial life (past or present) are to be expected in the coming years and decades, whether from within our own solar system, from an exoplanet atmosphere, or otherwise. With each such potential biosignature, the degree of our uncertainty will be the first question asked. Have we really identified extraterrestrial life? How sure are we? This paper considers the problem of unconceived alternative explanations. We stress that articulating our uncertainty requires an assessment of the extent to which we have explored the relevant possibility space. It is argued that, for most conceivable potential biosignatures, we currently have not explored the relevant possibility space very thoroughly at all. Not only does this severely limit the circumstances in which we could reasonably be confident in our detection of extraterrestrial life, it also poses a significant challenge to any attempt to quantify our degree of uncertainty. The discussion leads us to the following recommendation: when it comes specifically to an extraterrestrial life-detection claim, the astrobiology community should follow the uncertainty assessment approach adopted by the Intergovernmental Panel on Climate Change (IPCC).","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9942554","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":"Microbial Transport by a Descending Ice Melting Probe: Implications for Subglacial and Ocean World Exploration.","authors":"Caleb G Schuler, Dale P Winebrenner, W Timothy Elam, Justin Burnett, Bruce W Boles, Jill A Mikucki","doi":"10.1089/ast.2021.0106","DOIUrl":"10.1089/ast.2021.0106","url":null,"abstract":"<p><p>Ocean Worlds beneath thick ice covers in our solar system, as well as subglacial lakes on Earth, may harbor biological systems. In both cases, thick ice covers (>100 s of meters) present significant barriers to access. Melt probes are emerging as tools for reaching and sampling these realms due to their small logistical footprint, ability to transport payloads, and ease of cleaning in the field. On Earth, glaciers are immured with various abundances of microorganisms and debris. The potential for bioloads to accumulate around and be dragged by a probe during descent has not previously been investigated. Due to the pristine nature of these environments, minimizing and understanding the risk of forward contamination and considering the potential of melt probes to act as instrument-induced special regions are essential. In this study, we examined the effect that two engineering descent strategies for melt probes have on the dragging of bioloads. We also tested the ability of a field cleaning protocol to rid a common contaminant, <i>Bacillus</i>. These tests were conducted in a synthetic ice block immured with bioloads using the Ice Diver melt probe. Our data suggest minimal dragging of bioloads by melt probes, but conclude that modifications for further minimization and use in special regions should be made.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10154316","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":"Ice Transit and Performance Analysis for Cryorobotic Subglacial Access Missions on Earth and Europa.","authors":"Marc S Boxberg, Qian Chen, Ana-Catalina Plesa, Julia Kowalski","doi":"10.1089/ast.2021.0071","DOIUrl":"10.1089/ast.2021.0071","url":null,"abstract":"<p><p>Ice-covered ocean worlds, such as the Jovian moon Europa, are some of the prime targets for planetary exploration due to their high astrobiological potential. While upcoming space exploration missions, such as the Europa Clipper and JUICE missions, will give us further insight into the local cryoenvironment, any conclusive life detection investigation requires the capability to penetrate and transit the icy shell and access the subglacial ocean directly. Developing robust, autonomous cryorobotic technology for such a mission constitutes an extremely demanding multistakeholder challenge and requires a concentrated interdisciplinary effort between engineers, geoscientists, and astrobiologists. An important tool with which to foster cross-disciplinary work at an early stage of mission preparation is the virtual testbed. In this article, we report on recent progress in the development of an ice transit and performance model for later integration in such a virtual testbed. We introduce a trajectory model that, for the first time, allows for the evaluation of mission-critical parameters, such as transit time and average/overall power supply. Our workflow is applied to selected, existing cryobot designs while taking into consideration different terrestrial, as well as extraterrestrial, deployment scenarios. Specific analyses presented in this study show the tradeoff minimum transit time and maximum efficiency of a cryobot and allow for quantification of different sources of uncertainty to cryobot's trajectory models.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10444315","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":"Remote Laser-Induced Breakdown Spectroscopy of Bacterial Growths in Carbonate Rocks in a Mars-like Atmosphere.","authors":"Laura García-Gómez, Tomás Delgado, Francisco J Fortes, Yolanda Del Rosal, Cristina Liñán, Luis Efrén Fernández, Luisa M Cabalín, Javier Laserna","doi":"10.1089/ast.2022.0153","DOIUrl":"10.1089/ast.2022.0153","url":null,"abstract":"<p><p>Understanding the past habitable environments of Mars increases the requirement to recognize and examine modern analogs and to evaluate the mechanisms that may preserve biosignatures in them. The phenomenon that originates and preserves possible microbial biosignatures in mineral phases is of particular interest in astrobiology. On Earth, the precipitation of carbonate matrices can be mediated by bacteria. Besides microbialites and other sedimentary structures, carbonate formations can be observed in certain karstic caves. The present work is focused on the remote laser-induced breakdown spectroscopy (LIBS) characterization of cyanobacteria, exploring the possibilities for identification and discrimination on carbonate substrates. For this purpose, the extremophile cyanobacterium <i>Chroococcidiopsis</i> sp. (collected from the Nerja Cave, Malaga, Spain) was analyzed under laboratory-simulated martian conditions in terms of chemical composition and gas pressure. LIBS results related to acquired molecular emission features allowed bacterial differentiation from the colonized mineral substrate. In addition, the limits of detection were estimated with a laboratory-grown culture of the cyanobacterium <i>Microcystis aureginosa</i>. Our results reveal LIBS's capability to detect biological traces under simulated martian conditions. Additionally, the time-resolved analysis of the biological samples demonstrates the selection of optimal temporal conditions as a critical parameter for the preferential acquisition of molecular species in organic material.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41189650","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":"Is There Such a Thing as a Biosignature?","authors":"Christophe Malaterre, Inge Loes Ten Kate, Mickael Baqué, Vinciane Debaille, John Lee Grenfell, Emmanuelle J Javaux, Nozair Khawaja, Fabian Klenner, Yannick J Lara, Sean McMahon, Keavin Moore, Lena Noack, C H Lucas Patty, Frank Postberg","doi":"10.1089/ast.2023.0042","DOIUrl":"10.1089/ast.2023.0042","url":null,"abstract":"<p><p>The concept of a biosignature is widely used in astrobiology to suggest a link between some observation and a biological cause, given some context. The term itself has been defined and used in several ways in different parts of the scientific community involved in the search for past or present life on Earth and beyond. With the ongoing acceleration in the search for life in distant time and/or deep space, there is a need for clarity and accuracy in the formulation and reporting of claims. Here, we critically review the biosignature concept(s) and the associated nomenclature in light of several problems and ambiguities emphasized by recent works. One worry is that these terms and concepts may imply greater certainty than is usually justified by a rational interpretation of the data. A related worry is that terms such as \"biosignature\" may be inherently misleading, for example, because the divide between life and non-life-and their observable effects-is fuzzy. Another worry is that different parts of the multidisciplinary community may use non-equivalent or conflicting definitions and conceptions, leading to avoidable confusion. This review leads us to identify a number of pitfalls and to suggest how they can be circumvented. In general, we conclude that astrobiologists should exercise particular caution in deciding whether and how to use the concept of biosignature when thinking and communicating about habitability or life. Concepts and terms should be selected carefully and defined explicitly where appropriate. This would improve clarity and accuracy in the formulation of claims and subsequent technical and public communication about some of the most profound and important questions in science and society. With this objective in mind, we provide a checklist of questions that scientists and other interested parties should ask when assessing any reported detection of a \"biosignature\" to better understand exactly what is being claimed.</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92152529","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":"Does Gaia Play Dice? Simple Models of Non-Darwinian Selection.","authors":"Rudy Arthur, Arwen Nicholson","doi":"10.1089/ast.2023.0036","DOIUrl":"10.1089/ast.2023.0036","url":null,"abstract":"<p><p>In this article, we introduce some simple models, based on rolling dice, to explore mechanisms proposed to explain planetary habitability. The idea is to study these selection mechanisms in an analytically tractable setting, isolating their consequences from other details which can confound or obscure their effect in more realistic models. We find that the observable of interest, the face value shown on the die, \"improves\" over time in all models. For two of the more popular ideas, Selection by Survival and Sequential Selection, this is down to sampling effects. A modified version of Sequential Selection, Sequential Selection with Memory, implies a statistical tendency for systems to improve over time. We discuss the implications of this and its relationship to the ideas of the \"Inhabitance Paradox\" and the \"Gaian bottleneck.\"</p>","PeriodicalId":8645,"journal":{"name":"Astrobiology","volume":null,"pages":null},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"92152567","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}