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Astrobiology

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https://www.readbyqxmd.com/read/27925795/oxidants-at-the-surface-of-mars-a-review-in-light-of-recent-exploration-results
#1
J Lasne, A Noblet, C Szopa, R Navarro-González, M Cabane, O Poch, F Stalport, P François, S K Atreya, P Coll
In 1976, the Viking landers carried out the most comprehensive search for organics and microbial life in the martian regolith. Their results indicate that Mars' surface is lifeless and, surprisingly, depleted in organics at part-per-billion levels. Several biology experiments on the Viking landers gave controversial results that have since been explained by the presence of oxidizing agents on the surface of Mars. These oxidants may degrade abiotic or biological organics, resulting in their nondetection in the regolith...
December 7, 2016: Astrobiology
https://www.readbyqxmd.com/read/27912029/how-to-establish-a-bioregenerative-life-support-system-for-long-term-crewed-missions-to-the-moon-or-mars
#2
Yuming Fu, Leyuan Li, Beizhen Xie, Chen Dong, Mingjuan Wang, Boyang Jia, Lingzhi Shao, Yingying Dong, Shengda Deng, Hui Liu, Guanghui Liu, Bojie Liu, Dawei Hu, Hong Liu
To conduct crewed simulation experiments of bioregenerative life support systems on the ground is a critical step for human life support in deep-space exploration. An artificial closed ecosystem named Lunar Palace 1 was built through integrating efficient higher plant cultivation, animal protein production, urine nitrogen recycling, and bioconversion of solid waste. Subsequently, a 105-day, multicrew, closed integrative bioregenerative life support systems experiment in Lunar Palace 1 was carried out from February through May 2014...
December 2, 2016: Astrobiology
https://www.readbyqxmd.com/read/27912028/formation-and-persistence-of-brine-on-mars-experimental-simulations-throughout-the-diurnal-cycle-at-the-phoenix-landing-site
#3
E Fischer, G M Martínez, N O Rennó
In the last few years, water ice and salts capable of melting this ice and producing liquid saline water (brine) have been detected on Mars. Moreover, indirect evidence for brine has been found in multiple areas of the planet. Here, we simulate full diurnal cycles of temperature and atmospheric water vapor content at the Phoenix landing site for the first time and show experimentally that, in spite of the low Mars-like chamber temperature, brine forms minutes after the ground temperature exceeds the eutectic temperature of salts in contact with water ice...
December 2, 2016: Astrobiology
https://www.readbyqxmd.com/read/27905827/modeling-pn2-through-geological-time-implications-for-planetary-climates-and-atmospheric-biosignatures
#4
E E Stüeken, M A Kipp, M C Koehler, E W Schwieterman, B Johnson, R Buick
Nitrogen is a major nutrient for all life on Earth and could plausibly play a similar role in extraterrestrial biospheres. The major reservoir of nitrogen at Earth's surface is atmospheric N2, but recent studies have proposed that the size of this reservoir may have fluctuated significantly over the course of Earth's history with particularly low levels in the Neoarchean-presumably as a result of biological activity. We used a biogeochemical box model to test which conditions are necessary to cause large swings in atmospheric N2 pressure...
December 1, 2016: Astrobiology
https://www.readbyqxmd.com/read/27901343/colonization-of-snow-by-microorganisms-as-revealed-using-miniature-raman-spectrometers-possibilities-for-detecting-carotenoids-of-psychrophiles-on-mars
#5
Jan Jehlička, Adam Culka, Linda Nedbalová
We tested the potential of a miniaturized Raman spectrometer for use in field detection of snow algae pigments. A miniature Raman spectrometer, equipped with an excitation laser at 532 nm, allowed for the detection of carotenoids in cells of Chloromonas nivalis and Chlamydomonas nivalis at different stages of their life cycle. Astaxanthin, the major photoprotective pigment, was detected in algal blooms originating in snows at two alpine European sites that differed in altitude (Krkonoše Mts., Czech Republic, 1502 m a...
November 30, 2016: Astrobiology
https://www.readbyqxmd.com/read/27893284/biomarkers-and-metabolic-patterns-in-the-sediments-of-evolving-glacial-lakes-as-a-proxy-for-planetary-lake-exploration
#6
Víctor Parro, Yolanda Blanco, Fernando Puente-Sánchez, Luis A Rivas, Mercedes Moreno-Paz, Alex Echeverría, Guillermo Chong-Díaz, Cecilia Demergasso, Nathalie A Cabrol
Oligotrophic glacial lakes in the Andes Mountains serve as models to study the effects of climate change on natural biological systems. The persistent high UV regime and evolution of the lake biota due to deglaciation make Andean lake ecosystems potential analogues in the search for life on other planetary bodies. Our objective was to identify microbial biomarkers and metabolic patterns that represent time points in the evolutionary history of Andean glacial lakes, as these may be used in long-term studies as microscale indicators of climate change processes...
November 28, 2016: Astrobiology
https://www.readbyqxmd.com/read/27870556/twenty-species-of-hypobarophilic-bacteria-recovered-from-diverse-soils-exhibit-growth-under-simulated-martian-conditions-at-0-7%C3%A2-kpa
#7
Andrew C Schuerger, Wayne L Nicholson
Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 20 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 10 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from diverse soils, and high numbers of hypobarophiles were recovered from Arctic and Siberian permafrost soils...
November 21, 2016: Astrobiology
https://www.readbyqxmd.com/read/27870548/onboard-science-insights-and-vehicle-dynamics-from-scale-model-trials-of-the-titan-mare-explorer-time-capsule-at-laguna-negra-chile
#8
Ralph D Lorenz, Nathalie A Cabrol
A scale model of the proposed Titan Mare Explorer capsule was deployed at the Planetary Lake Lander field site at Laguna Negra, Chile. The tests served to calibrate models of wind-driven drift of the capsule and to understand its attitude motion in the wave field, as well as to identify dynamic and acoustic signatures of shoreline approach. This information enables formulation of onboard trigger criteria for near-shore science data acquisition. Key Words: Titan-Vehicle dynamics-Science autonomy-Lake. Astrobiology 17, xxx-xxx...
November 21, 2016: Astrobiology
https://www.readbyqxmd.com/read/27700137/carbon-monoxide-and-the-potential-for-prebiotic-chemistry-on-habitable-planets-around-main-sequence-m-stars
#9
J Manik Nava-Sedeño, Adrian Ortiz-Cervantes, Antígona Segura, Shawn D Domagal-Goldman
Lifeless planets with CO2 atmospheres produce CO by CO2 photolysis. On planets around M dwarfs, CO is a long-lived atmospheric compound, as long as UV emission due to the star's chromospheric activity lasts, and the sink of CO and O2 in seawater is small compared to its atmospheric production. Atmospheres containing reduced compounds, like CO, may undergo further energetic and chemical processing to give rise to organic compounds of potential importance for the origin of life. We calculated the yield of organic compounds from CO2-rich atmospheres of planets orbiting M dwarf stars, which were previously simulated by Domagal-Goldman et al...
October 4, 2016: Astrobiology
https://www.readbyqxmd.com/read/27870586/organic-matter-detection-on-mars-by-pyrolysis-ftir-an-analysis-of-sensitivity-and-mineral-matrix-effects
#10
Peter R Gordon, Mark A Sephton
Returning samples from Mars will require an effective method to assess and select the highest-priority geological materials. The ideal instrument for sample triage would be simple in operation, limited in its demand for resources, and rich in produced diagnostic information. Pyrolysis-Fourier infrared spectroscopy (pyrolysis-FTIR) is a potentially attractive triage instrument that considers both the past habitability of the sample depositional environment and the presence of organic matter that may reflect actual habitation...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27870585/another-earth-2-0-not-so-fast
#11
Dirk Schulze-Makuch, Edward Guinan
The number of confirmed exoplanets now exceeds 3000, with an additional nearly 5000 exoplanet candidates awaiting confirmation in the NASA Exoplanet Archive ( 2016 ). Nearly weekly we hear about the detection of a new exoplanet similar in mass to Earth and located in the so-called habitable zone around its host star. The excitement is understandable given our desire to find a second Earth. However, the excitement should not lead to an over-interpretation of the findings, because the claim can only be to have some crude similarity to Earth based on a few selected geophysical parameters...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27870584/follow-the-carbon-isotopic-labeling-studies-of-early-earth-aerosol
#12
Raea K Hicks, Douglas A Day, Jose L Jimenez, Margaret A Tolbert
Despite the faint young Sun, early Earth might have been kept warm by an atmosphere containing the greenhouse gases CH4 and CO2 in mixing ratios higher than those found on Earth today. Laboratory and modeling studies suggest that an atmosphere containing these trace gases could lead to the formation of organic aerosol haze due to UV photochemistry. Chemical mechanisms proposed to explain haze formation rely on CH4 as the source of carbon and treat CO2 as a source of oxygen only, but this has not previously been verified experimentally...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27870583/organic-matter-responses-to-radiation-under-lunar-conditions
#13
Richard Matthewman, Ian A Crawford, Adrian P Jones, Katherine H Joy, Mark A Sephton
Large bodies, such as the Moon, that have remained relatively unaltered for long periods of time have the potential to preserve a record of organic chemical processes from early in the history of the Solar System. A record of volatiles and impactors may be preserved in buried lunar regolith layers that have been capped by protective lava flows. Of particular interest is the possible preservation of prebiotic organic materials delivered by ejected fragments of other bodies, including those originating from the surface of early Earth...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27827540/meteorites-and-the-rna-world-a-thermodynamic-model-of-nucleobase-synthesis-within-planetesimals
#14
Ben K D Pearce, Ralph E Pudritz
The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We investigated the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identified the two most important reactions for each nucleobase and found that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27827533/fluctuation-analysis-of-redox-potential-to-distinguish-microbial-fe-ii-oxidation
#15
A M L Enright, F G Ferris
We developed a novel method for distinguishing abiotic and biological iron oxidation in liquid media using oxidation-reduction (redox) potential time series data. The instrument and processing algorithm were tested by immersing the tip of a Pt electrode with an Ag-AgCl reference electrode into an active iron-oxidizing biofilm in a groundwater discharge zone, as well as in two abiotic systems: a killed sample and a chemical control from the same site. We used detrended fluctuation analysis to characterize average root mean square fluctuation behavior, which was distinct in the live system...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27792417/the-pale-orange-dot-the-spectrum-and-habitability-of-hazy-archean-earth
#16
Giada Arney, Shawn D Domagal-Goldman, Victoria S Meadows, Eric T Wolf, Edward Schwieterman, Benjamin Charnay, Mark Claire, Eric Hébrard, Melissa G Trainer
Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects...
November 2016: Astrobiology
https://www.readbyqxmd.com/read/27732069/microbial-diversity-of-impact-generated-habitats
#17
Alexandra Pontefract, Gordon R Osinski, Charles S Cockell, Gordon Southam, Phil J A McCausland, Joseph Umoh, David W Holdsworth
Impact-generated lithologies have recently been identified as viable and important microbial habitats, especially within cold and arid regions such as the polar deserts on Earth. These unique habitats provide protection from environmental stressors, such as freeze-thaw events, desiccation, and UV radiation, and act to trap aerially deposited detritus within the fissures and pore spaces, providing necessary nutrients for endoliths. This study provides the first culture-independent analysis of the microbial community structure within impact-generated lithologies in a Mars analog environment, involving the analysis of 44,534 16S rRNA sequences from an assemblage of 21 rock samples that comprises three shock metamorphism categories...
October 2016: Astrobiology
https://www.readbyqxmd.com/read/27732068/hydrogen-isotopic-composition-of-arctic-and-atmospheric-ch4-determined-by-a-portable-near-infrared-cavity-ring-down-spectrometer-with-a-cryogenic-pre-concentrator
#18
Y Chen, Kevin K Lehmann, Y Peng, L M Pratt, J R White, S B Cadieux, B Sherwood Lollar, G Lacrampe-Couloume, T C Onstott
In this study, near-infrared continuous wave cavity ring-down spectroscopy was applied to the measurement of the δ(2)H of methane (CH4). The cavity ring-down spectrometer (CRDS) system consisted of multiple DFB laser diodes to optimize selection of spectral line pairs. By rapidly switching measurements between spectral line peaks and the baseline regions, the long-term instrumental drift was minimized, substantially increasing measurement precision. The CRDS system coupled with a cryogenic pre-concentrator measured the δ(2)H of terrestrial atmospheric CH4 from 3 standard liters of air with a precision of ±1...
October 2016: Astrobiology
https://www.readbyqxmd.com/read/27681637/contact-electrification-of-regolith-particles-and-chloride-electrolysis-synthesis-of-perchlorates-on-mars
#19
K Tennakone
Contact electrification of chloride-impregnated martian regolith particles due to eolian agitation and moisture condensation on coalesced oppositely charged grains may lead to spontaneous electrolysis that generates hypochlorite, chlorite, chlorate, and perchlorate with a concomitant reduction of water to hydrogen. This process is not curtailed even if moisture condenses as ice because chloride ionizes on the surface of ice. Limitations dictated by potentials needed for electrolysis and breakdown electric fields enable estimation of the required regolith grain size...
October 2016: Astrobiology
https://www.readbyqxmd.com/read/27631567/fermi-s-paradox-is-a-daunting-problem-under-whatever-label
#20
Milan M Ćirković
No abstract text is available yet for this article.
October 2016: Astrobiology
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