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1.
Genes (Basel) ; 11(1)2020 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-31936690

RESUMO

The MinION sequencer has made in situ sequencing feasible in remote locations. Following our initial demonstration of its high performance off planet with Earth-prepared samples, we developed and tested an end-to-end, sample-to-sequencer process that could be conducted entirely aboard the International Space Station (ISS). Initial experiments demonstrated the process with a microbial mock community standard. The DNA was successfully amplified, primers were degraded, and libraries prepared and sequenced. The median percent identities for both datasets were 84%, as assessed from alignment of the mock community. The ability to correctly identify the organisms in the mock community standard was comparable for the sequencing data obtained in flight and on the ground. To validate the process on microbes collected from and cultured aboard the ISS, bacterial cells were selected from a NASA Environmental Health Systems Surface Sample Kit contact slide. The locations of bacterial colonies chosen for identification were labeled, and a small number of cells were directly added as input into the sequencing workflow. Prepared DNA was sequenced, and the data were downlinked to Earth. Return of the contact slide to the ground allowed for standard laboratory processing for bacterial identification. The identifications obtained aboard the ISS, Staphylococcus hominis and Staphylococcus capitis, matched those determined on the ground down to the species level. This marks the first ever identification of microbes entirely off Earth, and this validated process could be used for in-flight microbial identification, diagnosis of infectious disease in a crewmember, and as a research platform for investigators around the world.


Assuntos
Sequenciamento por Nanoporos/métodos , RNA Ribossômico 16S/genética , Manejo de Espécimes/métodos , Bactérias/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Exobiologia/métodos , Meio Ambiente Extraterreno , Genoma Bacteriano/genética , Microbiota/genética , Nanoporos , Análise de Sequência de DNA/métodos , Astronave/instrumentação
2.
Electrophoresis ; 40(23-24): 3117-3122, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31599461

RESUMO

Future spaceflight missions focused on life detection will carry with them new, state-of-the-art instrumentation capable of highly selective and sensitive organic analysis. CE-LIF is an ideal candidate for such a mission due to its high separation efficiency and low LODs. One perceived risk of utilizing this technique on a future mission is the stability of the chemical reagents in the spaceflight environment. Here, we present an investigation of the thermal stability of the fluorescent dye (5-carboxyfluorescein succinimidyl ester) used for amino acid analysis. The dye was stored at 4, 25, and 60°C for 1 month, 6 months, 1 year, and 2 years. When stored at 4°C for 2 years, 25°C for 6 months, or 60°C for 1 month there was no effect on CE-LIF assay performance due to dye degradation. Beyond these time points, while the dye degradation begins to interfere with the analysis, it is still possible to perform the analysis and achieve the majority of amino acid biosignature science goals described in the science definition team report for the potential Europa Lander mission. This work indicates that thermal control of the dye at ≤4°C will be needed during transit on future spaceflight missions to maintain dye stability.


Assuntos
Aminoácidos/análise , Eletroforese Capilar/métodos , Exobiologia/métodos , Corantes Fluorescentes/análise , Corantes Fluorescentes/química , Estabilidade de Medicamentos , Temperatura Alta , Voo Espacial
3.
Life Sci Space Res (Amst) ; 22: 55-67, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31421849

RESUMO

In order to facilitate studies on the impact of the space environment on biological systems, we have developed a prototype of GEMM (Gene Expression Measurement Module) - an automated, miniaturized, integrated fluidic system for in-situ measurements of gene expression in microbial samples. The GEMM instrument is capable of (1) lysing bacterial cell walls, (2) extracting and purifying RNA released from cells, (3) hybridizing the RNA to probes attached to a microarray and (4) providing electrochemical readout, all in a microfluidics cartridge. To function on small, uncrewed spacecraft, the conventional, laboratory protocols for both sample preparation and hybridization required significant modifications. Biological validation of the instrument was carried out on Synechococcus elongatus, a photosynthetic cyanobacterium known for its metabolic diversity and resilience to adverse conditions. It was demonstrated that GEMM yielded reliable, reproducible gene expression profiles. GEMM is the only high throughput instrument that can be deployed in near future on space platforms other than the ISS to advance biological research in space. It can also prove useful for numerous terrestrial applications in the field.


Assuntos
Bactérias/isolamento & purificação , Exobiologia/métodos , Perfilação da Expressão Gênica/métodos , Automação , Bactérias/genética , Exobiologia/instrumentação , Perfilação da Expressão Gênica/instrumentação , Sequenciamento de Nucleotídeos em Larga Escala , Análise de Sequência com Séries de Oligonucleotídeos , Sensibilidade e Especificidade , Synechococcus/genética , Synechococcus/isolamento & purificação
4.
Int J Mol Sci ; 20(17)2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31438518

RESUMO

Astrochemistry and astrobiology, the fascinating disciplines that strive to unravel the origin of life, have opened unprecedented and unpredicted vistas into exotic compounds as well as extreme or complex reaction conditions of potential relevance for a broad variety of applications. Representative, and so far little explored sources of inspiration include complex organic systems, such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives; hydrogen cyanide (HCN) and formamide (HCONH2) oligomers and polymers, like aminomalononitrile (AMN)-derived species; and exotic processes, such as solid-state photoreactions on mineral surfaces, phosphorylation by minerals, cold ice irradiation and proton bombardment, and thermal transformations in fumaroles. In addition, meteorites and minerals like forsterite, which dominate dust chemistry in the interstellar medium, may open new avenues for the discovery of innovative catalytic processes and unconventional methodologies. The aim of this review was to offer concise and inspiring, rather than comprehensive, examples of astrochemistry-related materials and systems that may be of relevance in areas such as surface functionalization, nanostructures, and hybrid material design, and for innovative technological solutions. The potential of computational methods to predict new properties from spectroscopic data and to assess plausible reaction pathways on both kinetic and thermodynamic grounds has also been highlighted.


Assuntos
Exobiologia/métodos , Animais , Formamidas/química , Humanos , Cianeto de Hidrogênio , Nanoestruturas/química , Nitrilos/química , Hidrocarbonetos Policíclicos Aromáticos/química , Prebióticos
5.
EMBO Rep ; 20(7): e48541, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31267713

RESUMO

Experiments in space and on free-fall platforms have yielded important insights into plant's reaction to low gravity with potential applications for space research and exploration.


Assuntos
Fenômenos Fisiológicos Vegetais , Ausência de Peso , Produção Agrícola/métodos , Exobiologia/métodos , Simulação de Ambiente Espacial/métodos
6.
Arch Microbiol ; 201(6): 855-862, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30929030

RESUMO

Synthetic biology, the design and synthesis of synthetic biological systems from DNA to whole cells, has provided us with the ultimate tools for space exploration and colonisation. Herein, we explore some of the most significant advances and future prospects in the field of synthetic biology, in the context of astrobiology and terraforming.


Assuntos
Exobiologia/tendências , Biologia Sintética/tendências , DNA/síntese química , DNA/genética , Exobiologia/métodos , Voo Espacial , Biologia Sintética/métodos
7.
Environ Microbiol ; 21(7): 2440-2468, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30990927

RESUMO

Analysis of 16S ribosomal RNA (rRNA) gene amplification data for microbial barcoding can be inaccurate across complex environmental samples. A method, ANCHOR, is presented and designed for improved species-level microbial identification using paired-end sequences directly, multiple high-complexity samples and multiple reference databases. A standard operating procedure (SOP) is reported alongside benchmarking against artificial, single sample and replicated mock data sets. The method is then directly tested using a real-world data set from surface swabs of the International Space Station (ISS). Simple mock community analysis identified 100% of the expected species and 99% of expected gene copy variants (100% identical). A replicated mock community revealed similar or better numbers of expected species than MetaAmp, DADA2, Mothur and QIIME1. Analysis of the ISS microbiome identified 714 putative unique species/strains and differential abundance analysis distinguished significant differences between the Destiny module (U.S. laboratory) and Harmony module (sleeping quarters). Harmony was remarkably dominated by human gastrointestinal tract bacteria, similar to enclosed environments on earth; however, Destiny module bacteria also derived from nonhuman microbiome carriers present on the ISS, the laboratory's research animals. ANCHOR can help substantially improve sequence resolution of 16S rRNA gene amplification data within biologically replicated environmental experiments and integrated multidatabase annotation enhances interpretation of complex, nonreference microbiomes.


Assuntos
DNA Bacteriano/genética , Exobiologia/métodos , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Microbiologia Ambiental , Microbioma Gastrointestinal , Humanos , Microbiota , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Astronave , Especificidade da Espécie
8.
Astrobiology ; 19(3): 300-320, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840499

RESUMO

Biologic Analog Science Associated with Lava Terrains (BASALT) is a science-driven exploration program seeking to determine the best tools, techniques, training requirements, and execution strategies for conducting Mars-relevant field science under spaceflight mission conditions. BASALT encompasses Science, Science Operations, and Technology objectives. This article outlines the BASALT Science Operations background, strategic research questions, study design, and a portion of the results from the second field test. BASALT field tests are used to iteratively develop, integrate, test, evaluate, and refine new concepts of operations (ConOps) and capabilities that enable efficient and productive science. This article highlights the ConOps investigated during BASALT in light of future planetary extravehicular activity (EVA), which will focus on scientific exploration and discovery, and serves as an introduction to integrating exploration flexibility with operational rigor, the value of tactical and strategic science planning and execution, and capabilities that enable and enhance future science EVA operations.


Assuntos
Astronautas , Exobiologia/métodos , Atividade Extraespaçonave/fisiologia , Simulação de Ambiente Espacial , Eficiência , Hawaii , Humanos , Marte , Aptidão Física , Projetos de Pesquisa
9.
Astrobiology ; 19(3): 347-368, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840500

RESUMO

Short-term and long-term science plans were developed as part of the strategic planning process used by the Biologic Analog Science Associated with Lava Terrains (BASALT) science team to conduct two Mars-simulation missions investigating basalt habitability at terrestrial volcanic analog sites in 2016. A multidisciplinary team of scientists generated and codified a range of scientific hypotheses distilled into a Science Traceability Matrix (STM) that defined the set of objectives pursued in a series of extravehicular activity (EVA) campaigns performed across multiple field deployments. This STM was used to guide the pre-deployment selection of sampling stations within the selected Mars analog sites on the Earth based on precursor site information such as multispectral imagery. It also informed selection of hand-held instruments and observational data to collect during EVA to aid sample selection through latency-impacted interaction with an Earth-based Science Support Team. A significant portion of the pre-deployment strategic planning activities were devoted to station selection, ultimately the locations used for sample collection and EVA planning. During development of the EVAs, the BASALT science team identified lessons learned that could be used to inform future missions and analog activities, including the critical need for high-resolution precursor imagery that would enable the selection of stations that could meet the scientific objectives outlined in the STM.


Assuntos
Exobiologia/organização & administração , Atividade Extraespaçonave , Marte , Simulação de Ambiente Espacial/métodos , Planejamento Estratégico , Exobiologia/métodos , Exobiologia/tendências , Previsões
10.
Astrobiology ; 19(3): 284-299, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840501

RESUMO

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.


Assuntos
Biodiversidade , Exobiologia/métodos , Meio Ambiente Extraterreno/química , Microbiota , Erupções Vulcânicas , Archaea/genética , Archaea/isolamento & purificação , Bactérias/genética , Bactérias/isolamento & purificação , DNA Arqueal/genética , DNA Arqueal/isolamento & purificação , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Hawaii , Idaho , Marte , Filogenia , Silicatos/química
11.
Astrobiology ; 19(3): 369-386, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840503

RESUMO

The limitations placed upon human explorers on the surface of Mars will necessitate a methodology for scientific exploration that is different from standard approaches to terrestrial fieldwork and prior crewed exploration of the Moon. In particular, the data transmission limitations and communication latency between Earth and Mars create a unique situation for surface crew in contact with a terrestrial science team. The BASALT research program simulated a series of extravehicular activities (EVAs) in Mars analog terrains under various Mars-relevant bandwidth and latency conditions to investigate how best to approach this problem. Here we discuss tactical decision-making under these conditions, that is, how the crew on Mars interacts with a team of scientists and support personnel on Earth to collect samples of maximum scientific interest. We describe the strategies, protocols, and tools tested in BASALT EVAs and give recommendations on how best to conduct human exploration of Mars with support from Earth-based scientists. We find that even with scientists supporting them, the crew performing the exploration must be trained in the appropriate scientific disciplines in order to provide the terrestrial scientists with enough information to make decisions, but that with appropriate planning and structure, and tools such as a "dynamic leaderboard," terrestrial scientists can add scientific value to an EVA, even under Mars communication latency.


Assuntos
Astronautas/psicologia , Comunicação , Tomada de Decisões , Marte , Comunicações Via Satélite , Planeta Terra , Exobiologia/métodos , Meio Ambiente Extraterreno , Humanos , Astronave , Fatores de Tempo
12.
Astrobiology ; 19(3): 440-461, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840505

RESUMO

Future human missions to Mars are expected to emphasize scientific exploration. While recent Mars rover missions have addressed a wide range of science objectives, human extravehicular activities (EVAs), including the Apollo missions, have had limited experience with science operations. Current EVAs are carefully choreographed and guided continuously from Earth with negligible delay in communications between crew and flight controllers. Future crews on Mars will be expected to achieve their science objectives while operating and coordinating with a science team back on Earth under communication latency and bandwidth restrictions. The BASALT (Biologic Analog Science Associated with Lava Terrains) research program conducted Mars analog science on Earth to understand the concept of operations and capabilities needed to support these new kinds of EVAs. A suite of software tools (Minerva) was used for planning and executing all BASALT EVAs, supporting text communication across communication latency, and managing the collection of operational and scientific EVA data. This paper describes the support capabilities provided by Minerva to cope with various geospatial and temporal constraints to support the planning and execution phases of the EVAs performed during the BASALT research program. The results of this work provide insights on software needs for future science-driven planetary EVAs.


Assuntos
Exobiologia/organização & administração , Meio Ambiente Extraterreno , Marte , Voo Espacial/organização & administração , Simulação de Ambiente Espacial/métodos , Astronautas , Comunicação , Planeta Terra , Exobiologia/métodos , Exobiologia/tendências , Previsões , Humanos , Comunicações Via Satélite , Software , Voo Espacial/tendências , Planejamento Estratégico , Fatores de Tempo
13.
Astrobiology ; 19(3): 321-346, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840507

RESUMO

The Biologic Analog Science Associated with Lava Terrains (BASALT) research project is investigating tools, techniques, and strategies for conducting Mars scientific exploration extravehicular activity (EVA). This has been accomplished through three science-driven terrestrial field tests (BASALT-1, BASALT-2, and BASALT-3) during which the iterative development, testing, assessment, and refinement of concepts of operations (ConOps) and capabilities were conducted. ConOps are the instantiation of operational design elements that guide the organization and flow of personnel, communication, hardware, software, and data products to enable a mission concept. Capabilities include the hardware, software, data products, and protocols that comprise and enable the ConOps. This paper describes the simulation quality and acceptability of the Mars-forward ConOps evaluated during BASALT-2. It also presents the level of mission enhancement and acceptability of the associated Mars-forward capabilities. Together, these results inform science operations for human planetary exploration.


Assuntos
Exobiologia/métodos , Atividade Extraespaçonave , Marte , Pesquisa Operacional , Simulação de Ambiente Espacial/métodos , Exobiologia/instrumentação , Humanos , Simulação de Ambiente Espacial/instrumentação
14.
Astrobiology ; 19(3): 245-259, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30840510

RESUMO

The articles associated with this Special Collection focus on the NASA BASALT (Biologic Analog Science Associated with Lava Terrains) Research Program, which aims at answering the question, "How do we support and enable scientific exploration during human Mars missions?" To answer this the BASALT team conducted scientific field studies under simulated Mars mission conditions to both broaden our understanding of the habitability potential of basalt-rich terrains on Mars and examine the effects of science on current Mars mission concepts of operations. This article provides an overview of the BASALT research project, from the science, to the operational concepts that were tested and developed, to the technical capabilities that supported all elements of the team's research. Further, this article introduces the 12 articles that are included in this Special Collection.


Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno/química , Marte , Voo Espacial , Simulação de Ambiente Espacial , Astronautas , Humanos , Silicatos/química
15.
Astrobiology ; 19(3): 260-283, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30339033

RESUMO

Field research target regions within two basaltic geologic provinces are described as Earth analogs to Mars. Regions within the eastern Snake River Plain of Idaho and the Big Island of Hawai'i, the United States, provinces that represent analogs of present-day and early Mars, respectively, were evaluated on the basis of geologic settings, rock lithology and geochemistry, rock alteration, and climate. Each of these factors provides rationale for the selection of specific targets for field research in five analog target regions: (1) Big Craters and (2) Highway lava flows at Craters of the Moon National Monument and Preserve, Idaho, and (3) Mauna Ulu low shield, (4) Kilauea Iki lava lake, and (5) Kilauea caldera in the Kilauea Volcano summit region and the East Rift Zone of Hawai'i. Our evaluation of compositional and textural attributes, as well as the effects of syn- and posteruptive rock alteration, shows that basaltic terrains in Idaho and Hawai'i provide a way to characterize the geology and major geologic substrates that host biological activity of relevance to Mars exploration. This work provides the foundation to better understand the scientific questions related to the habitability of basaltic terrains, the rationale behind selecting analog field targets, and their applicability as analogs to Mars.


Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno/química , Marte , Erupções Vulcânicas , Hawaii , Idaho , Silicatos/química
16.
Astrobiology ; 19(1): 40-52, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30044121

RESUMO

Iron-oxidizing bacteria occupy a distinct environmental niche. These chemolithoautotrophic organisms require very little oxygen (when neutrophilic) or outcompete oxygen for access to Fe(II) (when acidophilic). The utilization of Fe(II) as an electron donor makes them strong analog organisms for any potential life that could be found on Mars. Despite their importance to the elucidation of early life on, and potentially beyond, Earth, many details of their metabolism remain unknown. By using on-line thermochemolysis and gas chromatography-mass spectrometry (GC-MS), a distinct signal for a low-molecular-weight molecule was discovered in multiple iron-oxidizing isolates as well as several iron-dominated environmental samples, from freshwater and marine environments and in both modern and older iron rock samples. This GC-MS signal was neither detected in organisms that did not use Fe(II) as an electron donor nor present in iron mats in which organic carbon was destroyed by heating. Mass spectral analysis indicates that the molecule bears the hallmarks of a pterin-bearing molecule. Genomic analysis has previously identified a molybdopterin that could be part of the electron transport chain in a number of lithotrophic iron-oxidizing bacteria, suggesting one possible source for this signal is the pterin component of this protein. The rock samples indicate the possibility that the molecule can be preserved within lithified sedimentary rocks. The specificity of the signal to organisms requiring iron in their metabolism makes this a novel biosignature with which to investigate both the evolution of life on ancient Earth and potential life on Mars.


Assuntos
Bactérias/metabolismo , Crescimento Quimioautotrófico , Microbiologia Ambiental , Exobiologia/métodos , Bactérias/isolamento & purificação , Marte
17.
Life Sci Space Res (Amst) ; 19: 13-16, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30482276

RESUMO

Finding life on other worlds is a fascinating area of astrobiology and planetary sciences. Presently, over 3800 exoplanets, representing a very wide range of physical and chemical environments, are known. Scientists are not only looking for traces of life outside Earth, but they are also trying to find out which of Earth's known organisms (ex: tardigrades (water bears)) would be able to survive on other planets. In our study, we have established a metric tool for distinguishing the potential survivability of active and cryptobiotic tardigrades on rocky-water and water-gas planets in our solar system and exoplanets, taking into consideration the geometrical means of six physical parameters such as radius, density, escape velocity, revolution period, surface temperature, and surface pressure of the considered planets. More than 3800 exoplanets are available as the main sample from Planetary Habitable Laboratory - Exoplanet Catalog (PHL-EC), from which we have chosen 57 exoplanets in our study including Earth and Mars, with water composition as reference. The Active Tardigrade Index (ATI) and Cryptobiotic Tardigrade Index (CTI) are two metric indices with minimum value 0 (= tardigrades cannot survive) and maximum 1 (= tardigrades will survive in their respective state). Values between 0 and 1 indicate a percentage chance of the active or cryptobiotic tardigrades surviving on a given exoplanet. Among known planets some of the exoplanets are tabulated as ATI and CTI indices for sample representation like: Kepler-100d, Kepler-48d, Kepler-289b, TRAPPIST-1 f and Kepler-106e. The results with Mars as the threshold indicates that Mars could be the only rock-water composition planet that could be more suitable for tardigrades than other considered exoplanets.


Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno , Planetas , Sistema Solar , Tardígrados , Animais , Temperatura , Água
19.
Electrophoresis ; 39(22): 2884-2889, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30112845

RESUMO

The search for biotic compounds beyond planet Earth is among the highest priorities in space discovery. We sought to detect organic molecules in various earth soil samples collected from environments with extreme climatic conditions comparable to extraterrestrial environments using HPLC, spectrophotometry (UV, IR), GC/MS and vertical gel electrophoresis analyses systems. The applied methods in the study were compared using a self-developed software tool that was designed to evaluate the viability of instrument selection for organics detection in any given exploratory mission. The tool was created to aid further development and refinements of rapidly improving technological solutions such as MCE and MS instruments. Such comparison can be done quickly and easily, acting as a decision support tool when choosing between analytical methods during any planning phase of future exploration missions led by space agencies (i.e., NASA).


Assuntos
Algoritmos , Técnicas de Química Analítica/métodos , Exobiologia/métodos , Meio Ambiente Extraterreno/química , Compostos Orgânicos/análise , Técnicas de Apoio para a Decisão , Voo Espacial
20.
Astrobiology ; 18(11): 1460-1478, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30124326

RESUMO

Assessing biosignature preservation potential (BPP) in ancient habitable environments on Mars is a top NASA priority. We address this goal through the study of Miocene-Pliocene evaporites of the Verde Formation (central Arizona). We assessed the effects of diagenesis on BPP, integrating outcrop-scale observations with six lab analyses: thin-section petrography, X-ray diffraction, Raman spectroscopy, total organic carbon (TOC), electron probe microanalysis (EPMA), and visible to near-infrared (VNIR) reflectance spectroscopy. We recognized five facies and their diagenetic pathways. Two facies included mudstones which contain clusters of displacive growth gypsum (DGG). Early DGG was altered during diagenesis by dissolution forming crystal cavities and later underwent recrystallization, cation substitution, and sulfate dehydration. Another facies was identified by lenticular beds dominated by halite and late diagenetic thenardite (Na2SO4). These pods are overlain by a sequence of interbedded gray and red mudstones which record cyclic oxidation and Fe-oxide cementation. During the Pleistocene, a lacustrine environment developed, accompanied by magnesite cementation of playa mudstones. TOC analyses were used as a proxy for inferring the BPP in each facies. The highest BPP was associated with both red and gray mudstone facies. This study provides a taphonomic framework for playa environments on Earth that record the impacts of diagenesis on BPP, with potential applications to Mars sample return (MSR) missions.


Assuntos
Exobiologia/métodos , Meio Ambiente Extraterreno , Marte , Minerais/química , Sulfato de Cálcio/química , Isótopos de Carbono , Sedimentos Geológicos/química , Mineração , Compostos Orgânicos/análise , Oxirredução , Análise Espectral Raman
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