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Astrobiology

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https://www.readbyqxmd.com/read/28323456/stratosphere-conditions-inactivate-bacterial-endospores-from-a-mars-spacecraft-assembly-facility
#1
Christina L Khodadad, Gregory M Wong, Leandro M James, Prital J Thakrar, Michael A Lane, John A Catechis, David J Smith
Every spacecraft sent to Mars is allowed to land viable microbial bioburden, including hardy endospore-forming bacteria resistant to environmental extremes. Earth's stratosphere is severely cold, dry, irradiated, and oligotrophic; it can be used as a stand-in location for predicting how stowaway microbes might respond to the martian surface. We launched E-MIST, a high-altitude NASA balloon payload on 10 October 2015 carrying known quantities of viable Bacillus pumilus SAFR-032 (4.07 × 10(7) spores per sample), a radiation-tolerant strain collected from a spacecraft assembly facility...
March 21, 2017: Astrobiology
https://www.readbyqxmd.com/read/28177270/biosignature-preservation-and-detection-in-mars-analog-environments
#2
Lindsay E Hays, Heather V Graham, David J Des Marais, Elisabeth M Hausrath, Briony Horgan, Thomas M McCollom, M Niki Parenteau, Sally L Potter-McIntyre, Amy J Williams, Kennda L Lynch
This review of material relevant to the Conference on Biosignature Preservation and Detection in Mars Analog Environments summarizes the meeting materials and discussions and is further expanded upon by detailed references to the published literature. From this diverse source material, there is a detailed discussion on the habitability and biosignature preservation potential of five primary analog environments: hydrothermal spring systems, subaqueous environments, subaerial environments, subsurface environments, and iron-rich systems...
February 8, 2017: Astrobiology
https://www.readbyqxmd.com/read/28151691/starlife-an-international-campaign-to-study-the-role-of-galactic-cosmic-radiation-in-astrobiological-model-systems
#3
Ralf Moeller, Marina Raguse, Stefan Leuko, Thomas Berger, Christine Elisabeth Hellweg, Akira Fujimori, Ryuichi Okayasu, Gerda Horneck
In-depth knowledge regarding the biological effects of the radiation field in space is required for assessing the radiation risks in space. To obtain this knowledge, a set of different astrobiological model systems has been studied within the STARLIFE radiation campaign during six irradiation campaigns (2013-2015). The STARLIFE group is an international consortium with the aim to investigate the responses of different astrobiological model systems to the different types of ionizing radiation (X-rays, γ rays, heavy ions) representing major parts of the galactic cosmic radiation spectrum...
February 2, 2017: Astrobiology
https://www.readbyqxmd.com/read/28151689/evaluation-of-the-resistance-of-chroococcidiopsis-spp-to-sparsely-and-densely-ionizing-irradiation
#4
Cyprien Verseux, Mickael Baqué, Riccardo Cifariello, Claudia Fagliarone, Marina Raguse, Ralf Moeller, Daniela Billi
Studying the resistance of cyanobacteria to ionizing radiation provides relevant information regarding astrobiology-related topics including the search for life on Mars, lithopanspermia, and biological life-support systems. Here, we report on the resistance of desert cyanobacteria of the genus Chroococcidiopsis, which were exposed (as part of the STARLIFE series of experiments) in both hydrated and dried states to ionizing radiation with different linear energy transfer values (0.2 to 200 keV/μm). Irradiation with up to 1 kGy of He or Si ions, 2 kGy of Fe ions, 5 kGy of X-rays, or 11...
February 2, 2017: Astrobiology
https://www.readbyqxmd.com/read/28323483/taphonomy-of-microbial-biosignatures-in-spring-deposits-a-comparison-of-modern-quaternary-and-jurassic-examples
#5
Sally L Potter-McIntyre, Jason Williams, Charity Phillips-Lander, Laura O'Connell
On Earth, microorganisms commonly enhance mineral precipitation and mediate mineralogical and chemical compositions of resulting deposits, particularly at spring systems. However, preservation of any type of microbial fossil or chemical or textural biosignature depends on the degree of alteration during diagenesis and factors such as exposure to diagenetic fluids. Little is known about the transformation of biosignatures during diagenesis over geologic time. Ten Mile Graben, Utah, USA, hosts a cold spring system that is an exceptional site for evaluation of diagenetic alteration of biosignatures because of the presence of modern springs with actively precipitating microbial mats and a series of progressively older tufa terraces (<400 ka) preserved in the area from the same spring system...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28323482/constraints-on-the-early-terrestrial-surface-uv-environment-relevant-to-prebiotic-chemistry
#6
Sukrit Ranjan, Dimitar D Sasselov
The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28323481/the-emergence-of-life-as-a-first-order-phase-transition
#7
Cole Mathis, Tanmoy Bhattacharya, Sara Imari Walker
It is well known that life on Earth alters its environment over evolutionary and geological timescales. An important open question is whether this is a result of evolutionary optimization or a universal feature of life. In the latter case, the origin of life would be coincident with a shift in environmental conditions. Here we present a model for the emergence of life in which replicators are explicitly coupled to their environment through the recycling of a finite supply of resources. The model exhibits a dynamic, first-order phase transition from nonlife to life, where the life phase is distinguished by selection on replicators...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28282220/identification-and-characterization-of-early-mission-phase-microorganisms-residing-on-the-mars-science-laboratory-and-assessment-of-their-potential-to-survive-mars-like-conditions
#8
Stephanie A Smith, James N Benardini, David Anderl, Matt Ford, Emmaleen Wear, Michael Schrader, Wayne Schubert, Linda DeVeaux, Andrzej Paszczynski, Susan E Childers
Planetary protection is governed by the Outer Space Treaty and includes the practice of protecting planetary bodies from contamination by Earth life. Although studies are constantly expanding our knowledge about life in extreme environments, it is still unclear what the probability is for terrestrial organisms to survive and grow on Mars. Having this knowledge is paramount to addressing whether microorganisms transported from Earth could negatively impact future space exploration. The objectives of this study were to identify cultivable microorganisms collected from the surface of the Mars Science Laboratory, to distinguish which of the cultivable microorganisms can utilize energy sources potentially available on Mars, and to determine the survival of the cultivable microorganisms upon exposure to physiological stresses present on the martian surface...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28282216/remote-sensing-of-potential-biosignatures-from-rocky-liquid-or-icy-exo-planetary-surfaces
#9
Olivier Poch, Joachim Frey, Isabel Roditi, Antoine Pommerol, Bernhard Jost, Nicolas Thomas
To detect signs of life by remote sensing on objects of our Solar System and on exoplanets, the characterization of light scattered by surface life material could complement possible clues given by the atmospheric composition. We reviewed the reflectance spectra of a broad selection of major biomolecules that constitute terrestrial carbon-based life from 0.4 to 2.4 μm, and we discuss their detectability through atmospheric spectral windows. Biomolecule features in the near-infrared (0.8-2.4 μm) will likely be obscured by water spectral features and some atmospheric gases...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28277783/origin-of-life-and-the-phosphate-transfer-catalyst
#10
Radosław W Piast, Rafał M Wieczorek
In this paper, we revisit several issues relevant to origin-of-life research and propose a Phosphate Transfer Catalyst hypothesis that furthers our understanding of some of the key events in prebiotic chemical evolution. In the Phosphate Transfer Catalyst hypothesis, we assume the existence of hypothetical metallopeptides with phosphate transfer activity that use abundant polyphosphates as both substrates and energy sources. Nonspecific catalysis by this phosphate transfer catalyst would provide a variety of different products such as phosphoryl amino acids, nucleosides, polyphosphate nucleotides, nucleic acids, and aminoacylated nucleic acids...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28263676/survival-and-dna-damage-in-plant-seeds-exposed-for-558-and-682-days-outside-the-international-space-station
#11
David Tepfer, Sydney Leach
For life to survive outside the biosphere, it must be protected from UV light and other radiation by exterior shielding or through sufficient inherent resistance to survive without protection. We tested the plausibility of inherent resistance in plant seeds, reporting in a previous paper that Arabidopsis thaliana and tobacco (Nicotiana tabacum) seeds exposed for 558 days outside the International Space Station (ISS) germinated and developed into fertile plants after return to Earth. We have now measured structural genetic damage in tobacco seeds from this EXPOSE-E experiment by quantitatively amplifying a segment of an antibiotic resistance gene, nptII, inserted into the chloroplast genome...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28206823/the-effect-of-high-dose-ionizing-radiation-on-the-isolated-photobiont-of-the-astrobiological-model-lichen-circinaria-gyrosa
#12
Joachim Meeßen, Theresa Backhaus, Annette Brandt, Marina Raguse, Ute Böttger, Jean-Pierre de Vera, Rosa de la Torre
Lichen symbioses between fungi and algae represent successful life strategies to colonize the most extreme terrestrial habitats. Consequently, space exposure and simulation experiments have demonstrated lichens' high capacity for survival, and thus, they have become models in astrobiological research with which to discern the limits and limitations of terrestrial life. In a series of ground-based irradiation experiments, the STARLIFE campaign investigated the resistance of astrobiological model organisms to galactic cosmic radiation, which is one of the lethal stressors of extraterrestrial environments...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206822/the-effect-of-high-dose-ionizing-radiation-on-the-astrobiological-model-lichen-circinaria-gyrosa
#13
Rosa de la Torre, Ana Zélia Miller, Beatriz Cubero, M Luisa Martín-Cerezo, Marina Raguse, Joachim Meeßen
The lichen Circinaria gyrosa is an astrobiological model defined by its high capacity of resistance to space conditions and to a simulated martian environment. Therefore, it became part of the currently operated BIOMEX experiment on board the International Space Station and the recent STARLIFE campaign to study the effects of four types of space-relevant ionizing radiation. The samples were irradiated with helium and iron ions at doses up to 2 kGy, with X-rays at doses up to 5 kGy and with γ rays at doses from 6 to 113 kGy...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206821/simulated-space-radiation-impact-of-four-different-types-of-high-dose-ionizing-radiation-on-the-lichen-xanthoria-elegans
#14
Annette Brandt, Joachim Meeßen, Reiner U Jänicke, Marina Raguse, Sieglinde Ott
This study addresses the viability of the lichen Xanthoria elegans after high-dose ionizing irradiation in the frame of the STARLIFE campaign. The first set of experiments was intended to resemble several types of galactic cosmic radiation (GCR) as present beyond the magnetic shield of Earth. In the second set of experiments, γ radiation up to 113 kGy was applied to test the limit of lichen resistance to ionizing radiation. Entire thalli of Xanthoria elegans were irradiated in the anhydrobiotic state. After STARLIFE 1, the metabolic activity of both symbionts was quantified by live/dead staining with confocal laser scanning microscopy...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28206820/tolerance-to-x-rays-and-heavy-ions-fe-he-in-the-tardigrade-richtersius-coronifer-and-the-bdelloid-rotifer-mniobia-russeola
#15
K Ingemar Jönsson, Andrzej Wojcik
The aim of this study was to analyze tolerance to heavy ions in desiccated animals of the eutardigrade Richtersius coronifer and the bdelloid rotifer Mniobia russeola within the STARLIFE project. Both species were exposed to iron (Fe) and helium (He) ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in Chiba, Japan, and to X-rays at the German Aerospace Center (DLR) in Cologne, Germany. Results show no effect of Fe and He on viability up to 7 days post-rehydration in both R. coronifer and M. russeola, while X-rays tended to reduce viability in R...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28151696/survival-dna-integrity-and-ultrastructural-damage-in-antarctic-cryptoendolithic-eukaryotic-microorganisms-exposed-to-ionizing-radiation
#16
Claudia Pacelli, Laura Selbmann, Laura Zucconi, Marina Raguse, Ralf Moeller, Igor Shuryak, Silvano Onofri
Life dispersal between planets, planetary protection, and the search for biosignatures are main topics in astrobiology. Under the umbrella of the STARLIFE project, three Antarctic endolithic microorganisms, the melanized fungus Cryomyces antarcticus CCFEE 515, a hyaline strain of Umbilicaria sp. (CCFEE 6113, lichenized fungus), and a Stichococcus sp. strain (C45A, green alga), were exposed to high doses of space-relevant gamma radiation ((60)Co), up to 117.07 kGy. After irradiation survival, DNA integrity and ultrastructural damage were tested...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28151694/the-effects-of-hze-particles-%C3%AE-and-x-ray-radiation-on-the-survival-and-genetic-integrity-of-halobacterium-salinarum-nrc-1-halococcus-hamelinensis-and-halococcus-morrhuae
#17
Stefan Leuko, Petra Rettberg
Three halophilic archaea, Halobacterium salinarum NRC-1, Halococcus hamelinensis, and Halococcus morrhuae, have been exposed to different regimes of simulated outer space ionizing radiation. Strains were exposed to high-energy heavy ion (HZE) particles, namely iron and argon ions, as well as to γ radiation ((60)Co) and X-rays, and the survival and the genetic integrity of the 16S rRNA gene were evaluated. Exposure to 1 kGy of argon or iron ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) facility at the National Institute for Radiological Sciences (NIRS) in Japan did not lead to a detectable loss in viability; only after exposure to 2 kGy of iron ions a decline in survival was observed...
February 2017: Astrobiology
https://www.readbyqxmd.com/read/28103108/secondary-school-students-knowledge-and-opinions-on-astrobiology-topics-and-related-social-issues
#18
Raquel Oreiro, Jordi Solbes
Astrobiology is the study of the origin of life on Earth and the distribution of life in the Universe. Its multidisciplinary approach, social and philosophical implications, and appeal within the discipline and beyond make astrobiology a uniquely qualified subject for general science education. In this study, student knowledge and opinions on astrobiology topics were investigated. Eighty-nine students in their last year of compulsory education (age 15) completed a written questionnaire that consisted of 10 open questions on the topic of astrobiology...
January 2017: Astrobiology
https://www.readbyqxmd.com/read/28103107/star-masses-and-star-planet-distances-for-earth-like-habitability
#19
David Waltham
This paper presents statistical estimates for the location and duration of habitable zones (HZs) around stars of different mass. The approach is based upon the assumption that Earth's location, and the Sun's mass, should not be highly atypical of inhabited planets. The results support climate-model-based estimates for the location of the Sun's HZ except models giving a present-day outer-edge beyond 1.64 AU. The statistical approach also demonstrates that there is a habitability issue for stars smaller than 0...
January 2017: Astrobiology
https://www.readbyqxmd.com/read/28103106/low-temperature-alkaline-ph-hydrolysis-of-oxygen-free-titan-tholins-carbonates-impact
#20
Coralie Brassé, Arnaud Buch, Patrice Coll, François Raulin
Titan, the largest moon of Saturn, is one of the key planetary objects in the field of exobiology. Its dense, nitrogen-rich atmosphere is the site of important organic chemistry. This paper focuses on the organic aerosols produced in Titan's atmosphere that play an important role in atmospheric and surface processes and in organic chemistry as it applies to exobiological interests. To produce reliable laboratory analogues of these aerosols, we developed, tested, and optimized a device for the synthesis of clean tholins...
January 2017: Astrobiology
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