1,407 results match your criteria Astrobiology[Journal]


Discriminating Abiotic and Biotic Fingerprints of Amino Acids and Fatty Acids in Ice Grains Relevant to Ocean Worlds.

Astrobiology 2020 Jun 3. Epub 2020 Jun 3.

Leibniz-Institute of Surface Engineering, Leipzig, Germany.

Identifying and distinguishing between abiotic and biotic signatures of organic molecules such as amino acids and fatty acids is key to the search for life on extraterrestrial ocean worlds. Impact ionization mass spectrometers can potentially achieve this by sampling water ice grains formed from ocean water and ejected by moons such as Enceladus and Europa, thereby exploring the habitability of their subsurface oceans in spacecraft flybys. Here, we extend previous high-sensitivity laser-based analog experiments of biomolecules in pure water to investigate the mass spectra of amino acids and fatty acids at simulated abiotic and biotic relative abundances. Read More

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http://dx.doi.org/10.1089/ast.2019.2188DOI Listing

Fluvial Regimes, Morphometry, and Age of Jezero Crater Paleolake Inlet Valleys and Their Exobiological Significance for the 2020 Rover Mission Landing Site.

Astrobiology 2020 May 28. Epub 2020 May 28.

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.

Jezero crater has been selected as the landing site for the Mars 2020 Perseverance rover, because it contains a paleolake with two fan-deltas, inlet and outlet valleys. Using the data from the High Resolution Stereo Camera (HRSC) and the High Resolution Imaging Science Experiment (HiRISE), we conducted a quantitative geomorphological study of the inlet valleys of the Jezero paleolake. Results show that the strongest erosion is related to a network of deep valleys that cut into the highland bedrock well upstream of the Jezero crater and likely formed before the formation of the regional olivine-rich unit. Read More

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http://dx.doi.org/10.1089/ast.2019.2132DOI Listing

Mars Extant Life: What's Next? Conference Report.

Astrobiology 2020 May 28. Epub 2020 May 28.

University of Texas, El Paso, Texas, USA.

On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. Read More

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http://dx.doi.org/10.1089/ast.2020.2237DOI Listing

Growth of Non-Halophilic Bacteria in the Sodium-Magnesium-Sulfate-Chloride Ion System: Unravelling the Complexities of Ion Interactions in Terrestrial and Extraterrestrial Aqueous Environments.

Astrobiology 2020 May 20. Epub 2020 May 20.

UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom.

Motivated by an interest in understanding the habitability of aqueous environments on Earth and in extraterrestrial settings, this study investigated the influence of ions in an artificial sodium-magnesium-sulfate-chloride ion system on the growth parameters (lag phase, growth rate, and final cell concentration) of bacteria. These four ions, in different combinations, are key components of many aqueous environments on Earth and elsewhere. We investigated non-halophilic bacteria deliberately to remove the bias of prior adaptations to high concentrations of selected ions so that we could compare the effects of different ions. Read More

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http://dx.doi.org/10.1089/ast.2019.2092DOI Listing

Estimated Minimum Life Span of the Jezero Fluvial Delta (Mars).

Astrobiology 2020 May 20. Epub 2020 May 20.

University of Lyon, ENSL, University of Lyon 1, CNRS, LGL-TPE, Lyon, France.

The paleo-lake floor at the edge of the Jezero delta has been selected as the NASA 2020 rover landing site. In this article, we demonstrate the sequences of lake filling and delta formation and constrain the minimum life span of the Jezero paleo-lake from sedimentological and hydrological analyses. Two main phases of delta evolution can be recognized by utilizing imagery provided by the High Resolution Imaging Science Experiment (NASA Mars Reconnaissance Orbiter) and High Resolution Stereo Camera (ESA Mars Express): (1) basin infilling before the breaching of the Jezero rim and (2) the delta formation itself. Read More

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http://dx.doi.org/10.1089/ast.2020.2228DOI Listing

Growth on Carbohydrates from Carbonaceous Meteorites Alters the Immunogenicity of Environment-Derived Bacterial Pathogens.

Astrobiology 2020 May 8. Epub 2020 May 8.

Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands.

The last decade has witnessed a renewed interest in space exploration. Public and private institutions are investing considerable effort toward the direct exploration of the Moon and Mars, as well as more distant bodies in the solar system. Both automated and human-crewed spacecraft are being considered in these efforts. Read More

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http://dx.doi.org/10.1089/ast.2019.2173DOI Listing

Observational Constraints on the Great Filter.

Astrobiology 2020 May;20(5):572-579

Blue Marble Space Institute of Science, Seattle, Washington.

The search for spectroscopic biosignatures with the next generation of space telescopes could provide observational constraints on the abundance of exoplanets with signs of life. An extension of this spectroscopic characterization of exoplanets is the search for observational evidence of technology, known as technosignatures. Current mission concepts that would observe biosignatures from ultraviolet to near-infrared wavelengths could place upper limits on the fraction of planets in the Galaxy that host life, although such missions tend to have relatively limited capabilities of constraining the prevalence of technosignatures at mid-infrared wavelengths. Read More

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http://dx.doi.org/10.1089/ast.2019.2154DOI Listing

Lichen Vitality After a Space Flight on Board the EXPOSE-R2 Facility Outside the International Space Station: Results of the Biology and Mars Experiment.

Astrobiology 2020 May;20(5):583-600

DLR-German Aerospace Center, Management and Infrastructure, Astrobiology Laboratories, Berlin, Germany.

As part of the Biology and Mars Experiment (BIOMEX; ILSRA 2009-0834), samples of the lichen were placed on the exposure platform EXPOSE-R2, on the International Space Station (ISS) and exposed to space and to a Mars-simulated environment for 18 months (2014-2016) to study: (1) resistance to space and Mars-like conditions and (2) biomarkers for use in future space missions (Exo-Mars). When the experiment returned (June 2016), initial analysis showed rapid recovery of photosystem II activity in the samples exposed exclusively to space vacuum and a Mars-like atmosphere. Significantly reduced recovery levels were observed in Sun-exposed samples, and electron and fluorescence microscopy (transmission electron microscope and field emission scanning electron microscope) data indicated that this was attributable to the combined effects of space radiation and space vacuum, as unirradiated samples exhibited less marked morphological changes compared with Sun-exposed samples. Read More

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http://dx.doi.org/10.1089/ast.2018.1959DOI Listing

Are We Alone? An Interview with Dr. Norman Sleep.

Astrobiology 2020 May;20(5):563-571

Professor of Geophysics, Stanford University, Palo Alto, California, USA.

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http://dx.doi.org/10.1089/ast.2020.0224DOI Listing

The Radiation Stability of Thymine in Solid HO.

Astrobiology 2020 Apr 21. Epub 2020 Apr 21.

Astrochemistry Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland.

Nucleobases are of significant importance to all known organisms, may be an important building block of life, and could be important biosignatures of current or past life. Given their potential significance to the field of astrobiology, it is important to understand the survival of these molecules when subjected to ionizing radiation as is present in a range of extraterrestrial environments. In this work, we present data on the kinetics of the radiolytic destruction of pure thymine and water + thymine ice mixtures at temperatures from 13 to 150 K. Read More

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http://dx.doi.org/10.1089/ast.2019.2199DOI Listing

Biological Soil Crusts as Modern Analogues for the Archean Continental Biosphere: Insights from Carbon and Nitrogen Isotopes.

Astrobiology 2020 Apr 15. Epub 2020 Apr 15.

Center for Fundamental and Applied Microbiomics, Biodesign Institute, and School of Life Sciences, Arizona State University, Tempe, Arizona.

Stable isotope signatures of elements related to life such as carbon and nitrogen can be powerful biomarkers that provide key information on the biological origin of organic remains and their paleoenvironments. Marked advances have been achieved in the last decade in our understanding of the coupled evolution of biological carbon and nitrogen cycling and the chemical evolution of the early Earth thanks, in part, to isotopic signatures preserved in fossilized microbial mats and organic matter of marine origin. However, the geologic record of the early continental biosphere, as well as its evolution and biosignatures, is still poorly constrained. Read More

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http://dx.doi.org/10.1089/ast.2019.2144DOI Listing

0.25 Ga Salt Deposits Preserve Signatures of Habitable Conditions and Ancient Lipids.

Astrobiology 2020 Apr 15. Epub 2020 Apr 15.

STFC Boulby Underground Laboratory, Boulby, United Kingdom.

Polygonal features in a ∼250 million-year-old Permian evaporitic deposit were investigated for their geological and organic content to test the hypothesis that they could preserve the signature of ancient habitable conditions and biological activity. Investigations on evaporitic rock were carried out as part of the MIne Analog Research (MINAR) project at Boulby Mine, the United Kingdom. The edges of the polygons have a higher clay content and contain higher abundances of minerals such as quartz and microcline, and clays such as illite and chlorite, compared with the interior of polygons, suggesting that the edges were preferred locations for the accumulation of weathering products during their formation. Read More

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http://dx.doi.org/10.1089/ast.2019.2053DOI Listing

Center for Astrobiology: Toward the RNA-World in the Interstellar Medium-Detection of Urea and Search of 2-Amino-oxazole and Simple Sugars.

Astrobiology 2020 Apr 17. Epub 2020 Apr 17.

INAF-Osservatorio Astrofisico di Arcetri, Florence, Italy.

In the past decade, astrochemistry has witnessed an impressive increase in the number of detections of complex organic molecules. Some of these species are of prebiotic interest such as glycolaldehyde, the simplest sugar, or aminoacetonitrile, a possible precursor of glycine. Recently, we have reported the detection of two new nitrogen-bearing complex organics, glycolonitrile and Z-cyanomethanimine, known to be intermediate species in the formation process of ribonucleotides within theories of a primordial RNA-world for the origin of life. Read More

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http://dx.doi.org/10.1089/ast.2019.2125DOI Listing

BioSentinel: A Biological CubeSat for Deep Space Exploration.

Astrobiology 2020 Apr 13. Epub 2020 Apr 13.

NASA Ames Research Center, Moffett Field, California.

BioSentinel is the first biological CubeSat designed and developed for deep space. The main objectives of this NASA mission are to assess the effects of deep space radiation on biological systems and to engineer a CubeSat platform that can autonomously support and gather data from model organisms hundreds of thousands of kilometers from Earth. The articles in this special collection describe the extensive optimization of the biological payload system performed in preparation for this long-duration deep space mission. Read More

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http://dx.doi.org/10.1089/ast.2019.2068DOI Listing

Ultraviolet-Driven Deamination of Cytidine Ribonucleotides Under Planetary Conditions.

Astrobiology 2020 Apr 8. Epub 2020 Apr 8.

Department of Astronomy, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts.

A previously proposed synthesis of pyrimidine ribonucleotides makes use of ultraviolet (UV) light to convert β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate, while simultaneously selectively degrading synthetic byproducts. Past studies of the photochemical reactions of pyrimidines have employed mercury arc lamps, characterized by narrowband emission centered at 254 nm, which is not representative of the UV environment of the early Earth. To further assess this process under more realistic circumstances, we investigated the wavelength dependence of the UV-driven conversion of β-d-ribocytidine-2',3'-cyclic phosphate to β-d-ribouridine-2',3'-cyclic phosphate. Read More

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http://dx.doi.org/10.1089/ast.2019.2182DOI Listing

Exo-Ocean Exploration with Deep-Sea Sensor and Platform Technologies.

Astrobiology 2020 Apr 8. Epub 2020 Apr 8.

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.

One of Saturn's largest moons, Enceladus, possesses a vast extraterrestrial ocean ( exo-ocean) that is increasingly becoming the hotspot of future research initiatives dedicated to the exploration of putative life. Here, a new bio-exploration concept design for Enceladus' exo-ocean is proposed, focusing on the potential presence of organisms across a wide range of sizes ( from uni- to multicellular and animal-like), according to state-of-the-art sensor and robotic platform technologies used in terrestrial deep-sea research. In particular, we focus on combined direct and indirect life-detection capabilities, based on optoacoustic imaging and passive acoustics, as well as molecular approaches. Read More

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http://dx.doi.org/10.1089/ast.2019.2129DOI Listing

Molecular Muscle Experiment: Hardware and Operational Lessons for Future Astrobiology Space Experiments.

Astrobiology 2020 Apr 8. Epub 2020 Apr 8.

MRC Versus Arthritis Centre for Musculoskeletal Ageing Research and NIHR Nottingham BRC, University of Nottingham, Medical School Royal Derby Hospital, Derby, United Kingdom.

Biology experiments in space seek to increase our understanding of what happens to life beyond Earth and how we can safely send life beyond Earth. Spaceflight is associated with many (mal)adaptations in physiology, including decline in musculoskeletal, cardiovascular, vestibular, and immune systems. Biological experiments in space are inherently challenging to implement. Read More

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http://dx.doi.org/10.1089/ast.2019.2181DOI Listing

Large Mass-Independent Oxygen Isotope Fractionations in Mid-Proterozoic Sediments: Evidence for a Low-Oxygen Atmosphere?

Astrobiology 2020 May 31;20(5):628-636. Epub 2020 Mar 31.

Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel.

Earth's ocean-atmosphere system has undergone a dramatic but protracted increase in oxygen (O) abundance. This environmental transition ultimately paved the way for the rise of multicellular life and provides a blueprint for how a biosphere can transform a planetary surface. However, estimates of atmospheric oxygen levels for large intervals of Earth's history still vary by orders of magnitude-foremost for Earth's middle history. Read More

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http://dx.doi.org/10.1089/ast.2019.2060DOI Listing

Microgravity Affects the Level of Matrix Polysaccharide 1,3:1,4-β-Glucans in Cell Walls of Rice Shoots by Increasing the Expression Level of a Gene Involved in Their Breakdown.

Astrobiology 2020 Mar 24. Epub 2020 Mar 24.

Advanced Engineering Services Co., Ltd., Tsukuba, Japan.

The plant cell wall provides each cell with structural support and mechanical strength, and thus, it plays an important role in supporting the plant body against the gravitational force. We investigated the effects of microgravity on the composition of cell wall polysaccharides and on the expression levels of genes involved in cell wall metabolism using rice shoots cultivated under artificial 1 and microgravity conditions on the International Space Station. The bulk amount of the cell wall obtained from microgravity-grown shoots was comparable with that from 1 -grown shoots. Read More

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http://dx.doi.org/10.1089/ast.2019.2140DOI Listing

An Oxygen Delivery Polymer Enhances Seed Germination in a Mars-like Environment.

Astrobiology 2020 Mar 20. Epub 2020 Mar 20.

Kimberly-Clark Corp., Roswell, Georgia.

Critical to the success of establishing a sustainable human presence on Mars is the ability to economically grow crop plants. Several environmental factors make it difficult to fully rely on local resources for agriculture. These include nutrient sparse regolith, low and fluctuating temperatures, a high amount of ultraviolet radiation, and water trapped locally in the form of ice or metal oxides. Read More

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http://dx.doi.org/10.1089/ast.2019.2056DOI Listing

AMADEE-18 and the Analog Mission Performance Metrics Analysis: A Benchmarking Tool for Mission Planning and Evaluation.

Astrobiology 2020 Mar 16. Epub 2020 Mar 16.

Department of Human Performance and Space, International Space University, Strasbourg, France.

Analog research of human or combined human and robotic missions is an established tool to explore the workflows, instruments, risks, and challenges of future planetary surface missions in a representative terrestrial environment. Analog missions that emulate selected aspects of such expeditions have risen in number, expanded their range of disciplines covered, and seen a significant increase in their operational and programmatic impact on mission planning. We propose a method to compare analog missions across agencies, disciplines, and complexities/fidelities to improve scientific output and mission safety and maximize effectiveness and efficiency. Read More

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http://dx.doi.org/10.1089/ast.2019.2034DOI Listing

Biosignature Analysis of Mars Soil Analogs from the Atacama Desert: Challenges and Implications for Future Missions to Mars.

Astrobiology 2020 Mar 11. Epub 2020 Mar 11.

Astrobiology Laboratory, Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, Leiden, The Netherlands.

The detection of biosignatures on Mars is of outstanding interest in the current field of Astrobiology and drives various fields of research, ranging from new sample collection strategies to the development of more sensitive detection techniques. Detailed analysis of the organic content in Mars analog materials collected from extreme environments on Earth improves the current understanding of biosignature preservation and detection under conditions similar to those of Mars. In this article, we examined the biological fingerprint of several locations in the Atacama Desert (Chile), which include different wet and dry, and intermediate to high elevation salt flats (also named salars). Read More

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http://dx.doi.org/10.1089/ast.2019.2063DOI Listing

Mars Rover Techniques and Lower/Middle Cambrian Microbialites from South Australia: Construction, Biofacies, and Biogeochemistry.

Astrobiology 2020 May 10;20(5):637-657. Epub 2020 Mar 10.

Department of Biological Sciences, Macquarie University, Sydney, Australia.

The Perseverance rover (Mars 2020) is equipped with an instrumental and analytical payload capable of identifying a broad range of organic molecules in geological samples. To determine the efficacy of these analytical techniques in recognizing important ecological and environmental signals in the rock record, this study utilized analogous equipment, including gas chromatography/mass spectrometry, Raman spectroscopy, X-ray fluorescence (XRF), Fourier transform infrared spectroscopy, along with macroscopic and petrographic observations, to examine early-middle Cambrian microbialites from the Arrowie Basin, South Australia. Morphological and petrographic observations of these carbonate successions reveal evidence of hypersaline-restricted environments. Read More

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http://dx.doi.org/10.1089/ast.2019.2110DOI Listing

The Impact of Molecular Oxygen on Anion Composition in a Hazy Archean Earth Atmosphere.

Astrobiology 2020 May 10;20(5):658-669. Epub 2020 Mar 10.

Department of Chemistry, University of Colorado, Boulder, Colorado.

Atmospheric organic hazes are common in planetary bodies in our solar system and likely exoplanet atmospheres as well. In addition, geochemical data support the existence of an organic haze in the early Earth's atmosphere. Much of what is known about organic haze formation derives from studies of Saturn's moon Titan. Read More

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http://dx.doi.org/10.1089/ast.2019.2145DOI Listing

Biomolecules from Fossilized Hot Spring Sinters: Implications for the Search for Life on Mars.

Astrobiology 2020 Apr 5;20(4):537-551. Epub 2020 Mar 5.

Australian Centre for Astrobiology (ACA) and PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales Sydney, Sydney, Australia.

Hot spring environments are commonly dominated by silica sinters that precipitate by the rapid cooling of silica-saturated fluids and the activity of microbial communities. However, the potential for preservation of organic traces of life in silica sinters back through time is not well understood. This is important for the exploration of early life on Earth and possibly Mars. Read More

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http://dx.doi.org/10.1089/ast.2018.2018DOI Listing

Simulating Serpentinization as It Could Apply to the Emergence of Life Using the JPL Hydrothermal Reactor.

Astrobiology 2020 Mar;20(3):307-326

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California.

The molecules feeding life's emergence are thought to have been provided through the hydrothermal interactions of convecting carbonic ocean waters with minerals comprising the early Hadean oceanic crust. Few laboratory experiments have simulated ancient hydrothermal conditions to test this conjecture. We used the JPL hydrothermal flow reactor to investigate CO reduction in simulated ancient alkaline convective systems over 3 days (T = 120°C,  = 100 bar, pH = 11). Read More

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http://dx.doi.org/10.1089/ast.2018.1949DOI Listing

Persistence of Habitable, but Uninhabited, Aqueous Solutions and the Application to Extraterrestrial Environments.

Astrobiology 2020 May 27;20(5):617-627. Epub 2020 Feb 27.

UK Centre for Astrobiology, School of Physics and Astronomy, James Clerk Maxwell Building, The King's Buildings, University of Edinburgh, Edinburgh, United Kingdom.

In most environments on Earth, habitable environments contain life. Experiments were conducted to investigate the decoupling of the presence of habitable conditions and life. A set of microcosms habitable for known groups of organisms, but uninhabited (, uninhabited habitats), was exposed to external environmental conditions to test the hypothesis that extreme habitable environments can remain uninhabited for sustained time periods. Read More

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http://dx.doi.org/10.1089/ast.2019.2179DOI Listing

The Production and Potential Detection of Hexamethylenetetramine-Methanol in Space.

Astrobiology 2020 May 27;20(5):601-616. Epub 2020 Feb 27.

NASA Ames Research Center, MS 245-3, Moffett Field, California 94035.

Numerous laboratory studies of astrophysical ice analogues have shown that their exposure to ionizing radiation leads to the production of large numbers of new, more complex compounds, many of which are of astrobiological interest. We show here that the irradiation of astrophysical ice analogues containing HO, CHOH, CO, and NH yields quantities of hexamethylenetetramine-methanol (hereafter HMT-methanol; CNHO) that are easily detectible in the resulting organic residues. This molecule differs from simple HMT, which is known to be abundant in similar ice photolysis residues, by the replacement of a peripheral H atom with a CHOH group. Read More

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http://dx.doi.org/10.1089/ast.2019.2147DOI Listing

Thiophenes on Mars: Biotic or Abiotic Origin?

Astrobiology 2020 Apr 24;20(4):552-561. Epub 2020 Feb 24.

Center for Astronomy and Astrophysics (ZAA), Astrobiology Research Group, Technische Universität Berlin, Berlin, Germany.

The question whether organic compounds occur on Mars remained unanswered for decades. However, the recent discovery of various classes of organic matter in martian sediments by the Curiosity rover seems to strongly suggest that indigenous organic compounds exist on Mars. One intriguing group of detected organic compounds were thiophenes, which typically occur on Earth in kerogen, coal, and crude oil as well as in stromatolites and microfossils. Read More

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http://dx.doi.org/10.1089/ast.2019.2139DOI Listing

Analog Site Experiment in the High Andes-Atacama Region: Surface Energy Budget Components on Ojos del Salado from Field Measurements and Weather Research and Forecasting Simulations.

Astrobiology 2020 Feb 12. Epub 2020 Feb 12.

Department of Meteorology, Eötvös Loránd University, Budapest, Hungary.

Remote sensing data are abundant, whereas surface verification of atmospheric conditions is rare on Mars. Earth-based analogues could help gain an understanding of soil and atmospheric processes on Mars and refine existing models. In this work, we evaluate the applicability of the Weather Research and Forecasting (WRF) model against measurements from the Mars analogue High Andes-Atacama Desert. Read More

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http://dx.doi.org/10.1089/ast.2019.2024DOI Listing
February 2020

Spores Onboard a Stratospheric NASA Balloon and Its Complete Life Cycle.

Astrobiology 2020 Mar 6;20(3):394-404. Epub 2020 Feb 6.

Dpto. de Ciencias de la Vida, Facultad de Ciencias, Universidad de Alcalá, 28805 Alcalá de Henares, Spain.

The aim of this study was to demonstrate for the first time spore viability in the stratosphere through spore germination and its complete life cycle. These protozoan spores were flown by the National Aeronautics and Space Administration (NASA) Columbia Scientific Balloon Facility (CSBF) flight 667NT, launched from its base in Fort Sumner, New Mexico. spores were exposed to stratospheric conditions on board the NASA/CSBF 667 balloon flight for 9 h. Read More

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http://dx.doi.org/10.1089/ast.2019.2097DOI Listing

Is a Linear or a Walkabout Protocol More Efficient When Using a Rover to Choose Biologically Relevant Samples in a Small Region of Interest?

Astrobiology 2020 Mar 5;20(3):327-348. Epub 2020 Feb 5.

Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado.

We conducted a field test at a potential Mars analog site to provide insight into planning for future robotic missions such as Mars 2020, where science operations must facilitate efficient choice of biologically relevant sampling locations. We compared two data acquisition and decision-making protocols currently used by Mars Science Laboratory: (1) a linear approach, where sites are examined as they are encountered and (2) a walkabout approach, in which the field site is first examined with remote rover instruments to gain an understanding of regional context followed by deployment of time- and power-intensive contact and sampling instruments on a smaller subset of locations. The walkabout method was advantageous in terms of both the time required to execute and a greater confidence in results and interpretations, leading to enhanced ability to tailor follow-on observations to better address key science and sampling goals. Read More

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http://dx.doi.org/10.1089/ast.2019.2090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071088PMC

Lipid Biomarkers in Ephemeral Acid Salt Lake Mudflat/Sandflat Sediments: Implications for Mars.

Astrobiology 2020 02;20(2):167-178

NASA Goddard Space Flight Center, Greenbelt, Maryland.

Sedimentary strata on Mars often contain a mix of sulfates, iron oxides, chlorides, and phyllosilicates, a mineral assemblage that is unique on Earth to acid brine environments. To help characterize the astrobiological potential of depositional environments with similar minerals present, samples from four naturally occurring acidic salt lakes and adjacent mudflats/sandflats in the vicinity of Norseman, Western Australia, were collected and analyzed. Lipid biomarkers were extracted and quantified, revealing biomarkers from vascular plants alongside trace microbial lipids. Read More

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http://dx.doi.org/10.1089/ast.2017.1812DOI Listing
February 2020

What Is Life-and When Do We Search for It on Other Worlds.

Astrobiology 2020 02;20(2):163-166

NASA Ames Research Center, Moffett Field, California.

There has been considerable attention on how to detect life on other worlds by searching for biomolecules. However, there has been much less clarity as to when it becomes warranted to focus a mission on the search for life on another world. At a minimum, a life-detection mission should follow convincing evidence of (1) Liquid water of suitable salinity, past or present; (2) Carbon in the water; (3) Biologically available N in the water; (4) Biologically useful energy in the water; (5) Organic material that can possibly be of biological origin and a plausible strategy for sampling this material. Read More

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http://dx.doi.org/10.1089/ast.2019.2136DOI Listing
February 2020

Testing Flight-like Pyrolysis Gas Chromatography-Mass Spectrometry as Performed by the Mars Organic Molecule Analyzer Onboard the ExoMars 2020 Rover on Oxia Planum Analog Samples.

Astrobiology 2020 Mar 27;20(3):415-428. Epub 2020 Jan 27.

Department of Geobiology, Geoscience Centre, University of Göttingen, Göttingen, Germany.

The Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2020 rover (to be landed in March 2021) utilizes pyrolysis gas chromatography-mass spectrometry (GC-MS) with the aim to detect organic molecules in martian (sub-) surface materials. Pyrolysis, however, may thermally destroy and transform organic matter depending on the temperature and nature of the molecules, thus altering the original molecular signatures. In this study, we tested MOMA flight-like pyrolysis GC-MS without the addition of perchlorates on well-characterized natural mineralogical analog samples for Oxia Planum, the designated ExoMars 2020 landing site. Read More

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http://dx.doi.org/10.1089/ast.2019.2143DOI Listing

ExoMars Raman Laser Spectrometer: A Tool for the Potential Recognition of Wet-Target Craters on Mars.

Astrobiology 2020 Mar 27;20(3):349-363. Epub 2020 Jan 27.

CSIC-CAB Associated Unit ERICA, Department of Condensed Matter Physics, University of Valladolid, Boecillo, Spain.

In the present work, near-infrared, laser-induced breakdown spectroscopy, Raman, and X-ray diffractometer techniques have been complementarily used to carry out a comprehensive characterization of a terrestrial analogue selected from the Chesapeake Bay impact structure (CBIS). The obtained data clearly highlight the key role of Raman spectroscopy in the detection of minor and trace compounds, through which inferences about geological processes occurred in the CBIS can be extrapolated. Beside the use of commercial systems, further Raman analyses were performed by the Raman laser spectrometer (RLS) ExoMars Simulator. Read More

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http://dx.doi.org/10.1089/ast.2019.2095DOI Listing

Detection of Potential Lipid Biomarkers in Oxidative Environments by Raman Spectroscopy and Implications for the ExoMars 2020-Raman Laser Spectrometer Instrument Performance.

Astrobiology 2020 Mar 27;20(3):405-414. Epub 2020 Jan 27.

Unidad Asociada UVa-CSIC al Centro de Astrobiología (CSIC-INTA), University of Valladolid, Valladolid, Spain.

The aim of the European Space Agency's ExoMars rover mission is to search for potential traces of present or past life in the swallow subsurface (2 m depth) of Mars. The ExoMars rover mission relies on a suite of analytical instruments envisioned to identify organic compounds with biological value (biomarkers) associated with a mineralogical matrix in a highly oxidative environment. We investigated the feasibility of detecting basic organics (linear and branched lipid molecules) with Raman laser spectroscopy, an instrument onboard the ExoMars rover, when exposed to oxidant conditions. Read More

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http://dx.doi.org/10.1089/ast.2019.2100DOI Listing

Growth of DSM17938 Under Two Simulated Microgravity Systems: Changes in Reuterin Production, Gastrointestinal Passage Resistance, and Stress Genes Expression Response.

Astrobiology 2020 01;20(1):1-14

Department of Agricultural Sciences, University of Naples Federico II, Portici, Italy.

Extreme factors such as space microgravity, radiation, and magnetic field differ from those that occur on Earth. Microgravity may induce and select some microorganisms for physiological, metabolic, and/or genetic variations. This study was conducted to determine the effects of simulated microgravity conditions on the metabolism and gene expression of the probiotic bacterium DSM17938. Read More

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http://dx.doi.org/10.1089/ast.2019.2082DOI Listing
January 2020

The Limits, Capabilities, and Potential for Life Detection with MinION Sequencing in a Paleochannel Mars Analog.

Astrobiology 2020 Mar 23;20(3):375-393. Epub 2020 Jan 23.

Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Quebec, Canada.

No instrument capable of direct life detection has been included on a mission payload to Mars since NASA's Viking missions in the 1970s. This prevents us from discovering whether life is or ever was present on Mars. DNA is an ideal target biosignature since it is unambiguous, nonspecific, and readily detectable with nanopore sequencing. Read More

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http://dx.doi.org/10.1089/ast.2018.1964DOI Listing

Simulating Mars Drilling Mission for Searching for Life: Lipids and Other Complex Microbial Biomarkers in the Iron-Sulfur Rich Río Tinto Analog.

Astrobiology 2020 Jan 9. Epub 2020 Jan 9.

Centro de Astrobiología (CSIC-INTA), Madrid, Spain.

Sulfate and iron oxide deposits in Río Tinto (Southwestern Spain) are a terrestrial analog of early martian hematite-rich regions. Understanding the distribution and drivers of microbial life in iron-rich environments can give critical clues on how to search for biosignatures on Mars. We simulated a robotic drilling mission searching for signs of life in the martian subsurface, by using a 1m-class planetary prototype drill mounted on a full-scale mockup of NASA's Phoenix and InSight lander platforms. Read More

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http://dx.doi.org/10.1089/ast.2019.2101DOI Listing
January 2020

Mawrth Vallis, Mars: A Fascinating Place for Future Exploration.

Astrobiology 2020 02 9;20(2):199-234. Epub 2020 Jan 9.

Institute of Geological Sciences, Planetary Sciences and Remote Sensing Group, Freie Universität Berlin, Berlin, Germany.

After the successful landing of the Mars Science Laboratory rover, both NASA and ESA initiated a selection process for potential landing sites for the Mars2020 and ExoMars missions, respectively. Two ellipses located in the Mawrth Vallis region were proposed and evaluated during a series of meetings (three for Mars2020 mission and five for ExoMars). We describe here the regional context of the two proposed ellipses as well as the framework of the objectives of these two missions. Read More

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http://dx.doi.org/10.1089/ast.2019.2074DOI Listing
February 2020

BioSentinel: Long-Term Preservation for a Deep Space Biosensor Mission.

Astrobiology 2020 Jan 3. Epub 2020 Jan 3.

Space Biosciences Research, NASA Ames Research Center, Moffett Field, California.

The biological risks of the deep space environment must be elucidated to enable a new era of human exploration and scientific discovery beyond low earth orbit (LEO). There is a paucity of deep space biological missions that will inform us of the deleterious biological effects of prolonged exposure to the deep space environment. To safely undertake long-term missions to Mars and space habitation beyond LEO, we must first prove and optimize autonomous biosensors to query the deep space radiation environment. Read More

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http://dx.doi.org/10.1089/ast.2019.2073DOI Listing
January 2020

Thermal Heads for Melt Drilling to Subglacial Lakes: Design and Testing.

Astrobiology 2020 01 3;20(1):142-156. Epub 2020 Jan 3.

Polar Research Center, Jilin University, Changchun, China.

Antarctic subglacial lakes are often considered suitable analogues to extraterrestrial subglacial aqueous environments. Recently, an environmentally friendly RECoverable Autonomous Sonde (RECAS) was designed at the Polar Research Center of Jilin University (JLU) to sample the water of subglacial lakes without contamination. In this regard, the development of a fast-penetration thermal head is the key issue for RECAS. Read More

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http://dx.doi.org/10.1089/ast.2019.2103DOI Listing
January 2020

Ceres: Astrobiological Target and Possible Ocean World.

Astrobiology 2020 02 3;20(2):269-291. Epub 2020 Jan 3.

Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California.

Ceres, the most water-rich body in the inner solar system after Earth, has recently been recognized to have astrobiological importance. Chemical and physical measurements obtained by the Dawn mission enabled the quantification of key parameters, which helped to constrain the habitability of the inner solar system's only dwarf planet. The surface chemistry and internal structure of Ceres testify to a protracted history of reactions between liquid water, rock, and likely organic compounds. Read More

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http://dx.doi.org/10.1089/ast.2018.1999DOI Listing
February 2020

Earth's Impact Events Through Geologic Time: A List of Recommended Ages for Terrestrial Impact Structures and Deposits.

Astrobiology 2020 01 27;20(1):91-141. Epub 2019 Dec 27.

Lunar and Planetary Institute-USRA, Houston, Texas.

This article presents a current (as of September 2019) list of recommended ages for proven terrestrial impact structures ( = 200) and deposits ( = 46) sourced from the primary literature. High-precision impact ages can be used to (1) reconstruct and quantify the impact flux in the inner Solar System and, in particular, the Earth-Moon system, thereby placing constraints on the delivery of extraterrestrial mass accreted on Earth through geologic time; (2) utilize impact ejecta as event markers in the stratigraphic record and to refine bio- and magneto-stratigraphy; (3) test models and hypotheses of synchronous double or multiple impact events in the terrestrial record; (4) assess the potential link between large impacts, mass extinctions, and diversification events in the biosphere; and (5) constrain the duration of melt sheet crystallization in large impact basins and the lifetime of hydrothermal systems in cooling impact craters, which may have served as habitats for microbial life on the early Earth and, possibly, Mars. Read More

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http://dx.doi.org/10.1089/ast.2019.2085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6987741PMC
January 2020

Accuracy of Thermodynamic Databases for Hydroxyapatite Dissolution Constant.

Astrobiology 2020 01 27;20(1):157-160. Epub 2019 Dec 27.

Brookhaven National Laboratory, Environmental and Climate Sciences, Upton, New York.

Discrepancies have been noted in the solubility constant values of calcium phosphate minerals between various databases employed in widely used aqueous speciation calculation software programs. This can cause serious errors in the calculated speciation of waters when using these software programs. The aim of this communication was to bring to light these discrepancies. Read More

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http://dx.doi.org/10.1089/ast.2019.2158DOI Listing
January 2020

Sulfur Chemistry May Have Paved the Way for Evolution of Antioxidants.

Astrobiology 2020 May 27;20(5):670-675. Epub 2019 Dec 27.

Space Biosciences Research (Code SCR), NASA Ames Research Center, Mountain View, California.

The first organisms on the young Earth, just 1-1.5 billion years old, were likely chemolithoautotrophic anaerobes, thriving in an anoxic world rich in water, CO, and N. It is generally assumed that, until the accumulation of O in the atmosphere, life was exempted from the oxidative stress that reactive oxygen species (ROS) impose on hydrocarbon-based life. Read More

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http://dx.doi.org/10.1089/ast.2019.2156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232690PMC

First Detections of Dichlorobenzene Isomers and Trichloromethylpropane from Organic Matter Indigenous to Mars Mudstone in Gale Crater, Mars: Results from the Sample Analysis at Mars Instrument Onboard the Curiosity Rover.

Astrobiology 2020 02 26;20(2):292-306. Epub 2019 Dec 26.

LATMOS/IPSL, UVSQ Université Paris-Saclay, UPMC Univ. Paris 06, CNRS, Guyancourt, France.

Chromatographic analysis of the Cumberland mudstone in Gale crater by the Sample Analysis at Mars (SAM) instrument revealed the detection of two to three isomers of dichlorobenzene. Their individual concentrations were estimated to be in the 0.5-17 ppbw range relative to the sample mass. Read More

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http://dx.doi.org/10.1089/ast.2018.1908DOI Listing
February 2020