166 research outputs found
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Microbial preservation in sulfates in the Haughton impact structure suggests target in search for life on Mars
Microbes occur within transparent gypsum crystals in the Haughton crater. The crystals transmit light for photosynthesis, but protect from dehydration and wind. Sulfates on the Martian surface should be a priority target in the search for life
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Simple devices for concentration of microbial life: Experiments in Haughton impact structure
Simple devices that create environments with high levels of light and moisture could attract extant microbial life on a planetary surface and hence enhance the detection of it. Experience in the Haughton crater shows that this can occur readily
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Surface mineral crusts: A priority target in search for life on Mars
Mineral crusts are strong candidates in the search for evidence of life during planetary exploration, and should be an important target for examination in impact craters. Crusts in the Haughton crater readily yield a biological signature
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Hopane biomarkers traced from bedrock to recent sediments and ice at the Haughton Impact Structure, Devon Island: Implications for the search for biomarkers on Mars
Hopanoid biomarkers have been traced from bedrock to ice in the Haughton Impact Structure, suggesting that they represent a promising strategy in the search for life in ice deposits on Mars and other icy bodies
Constraining the Temperature of Impact Melt from the Mistastin Lake Impact Structure Using Zircon Crystal Structures
Impact melt is a product of hyper-velocity impact events formed by the instantaneous melting of near-surface target rocks. Constraining the temperature of impact melt is vital to understanding its prograde heating and cooling history, which can have implications for inferring the environment of early Earth ~4.0 billion years ago when microbial life potentially arose. To date, only one datum on the initial impact melt temperature has been derived by Timms et al. These authors studied zirconia microstructures and crystallographic orientations that revealed the former presence of cubic zirconia, found in a black impact glass at the Mistastin Lake impact structure, Canada. The presence of cubic zirconia indicates a minimum temperature for the impact melt of >2370C from the dissociation temperature of zircon to cubic zirconia and liquid SiO2. With only one temperature datum, it is still difficult to constrain the entire temperature range experienced during the impact melting process; from its instantaneous formation to thermal equilibrium with the cold clasts collected along the crater floor and walls. In addition, obtaining a temperature value from only one type of impactite limits the inferred temperature range, because each impactite experiences a different cooling history. In this study, we present a preliminary investigation of 61 zircon crystals, 14 of which are similar to those studied by Timms et al., from the Mistastin Lake impact structure. To acquire a more accurate temperature profile representative of impact melt, zircon crystals were collected from different types of impactites containing impact melt, including additional samples of the black impact glass studied by Timms et al
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The Stac Fada “impact ejecta” layer: not what it seems
The Stac Fada Member (SFM) forms part of the Stoer Group of the Torridonian of NW Scotland. The SFM is unique in the Torridonian, being characterized by the presence of greenish altered glass clasts. Its origin has been debated for decades with several hypotheses being proposed but all invoking some connection with volcanic activity in the region. More recently, Amor et al. suggested that the SFM represents “a chord section through the continuous ejecta blanket surrounding an impact crater”. Here, we confirm the presence of shocked material within the SFM and then discuss its origin
BIOMECHANICAL VALIDATION OF A QUALITATIVE ANALYSIS OF BASEBALL PITCHING
Correct biomechanics minimise the risk of injury and improve performance during baseball pitching. The mechanics of 20 youth pitchers were analysed during outdoor practice using digital camcorders and a checklist of kinematic and temporal elements. The pitchers were also analysed indoors with a six-camera 240Hz Motion Analysis System. In both conditions, mechanics were graded using accepted norms for youth pitchers. Kappa coefficients were calculated between the qualitative measurements and motion analysis data for 17 kinematic parameters. 11 variables showed acceptable relationships between qualitative and quantitative data, indicating the practical value of this qualitative analysis as a field tool
Role of Meteorite Impacts in the Origin of Life
The conditions, timing, and setting for the origin of life on Earth and whether life exists elsewhere in our solar system and beyond represent some of the most fundamental scientific questions of our time. Although the bombardment of planets and satellites by asteroids and comets has long been viewed as a destructive process that would have presented a barrier to the emergence of life and frustrated or extinguished life, we provide a comprehensive synthesis of data and observations on the beneficial role of impacts in a wide range of prebiotic and biological processes. In the context of previously proposed environments for the origin of life on Earth, we discuss how meteorite impacts can generate both subaerial and submarine hydrothermal vents, abundant hydrothermal–sedimentary settings, and impact analogues for volcanic pumice rafts and splash pools. Impact events can also deliver and/or generate many of the necessary chemical ingredients for life and catalytic substrates such as clays as well. The role that impact cratering plays in fracturing planetary crusts and its effects on deep subsurface habitats for life are also discussed. In summary, we propose that meteorite impact events are a fundamental geobiological process in planetary evolution that played an important role in the origin of life on Earth. We conclude with the recommendation that impact craters should be considered prime sites in the search for evidence of past life on Mars. Furthermore, unlike other geological processes such as volcanism or plate tectonics, impact cratering is ubiquitous on planetary bodies throughout the Universe and is independent of size, composition, and distance from the host star. Impact events thus provide a mechanism with the potential to generate habitable planets, moons, and asteroids throughout the Solar System and beyond
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An infrared study of modern and paleo-filamentous bacteria from Rio Tinto, Spain
The Rio Tinto River Basin in southwestern Spain is a natural acidic (pH ~2.3) drainage system that supports a diversity of acid tolerant bacteria and eukaryotes with iron and sulfur- oxidizing prokaryotes performing chemolithotrophy and supporting anaerobic respiration [1, 2]. River terrace deposits formed over the past 2 Myr have preserved remnants of this unique biosphere, particularly microbial filaments, which provide templates for iron sulphate and iron oxide precipitation [1, 2]. This process of permineralization causes organic material to become trapped within a mineral matrix and preserved over geological time.
This study analysed cultured filamentous bacteria, modern biofilms and sediments, and river terrace deposits spanning 2.1 Myr to assess the preservation of organics in this extreme environment over time, and the ability to correlate them with a contemporary culture.
Filamentous bacteria are preserved within optically translucent nanophase to crystalline jarosite and goethite within all samples. The cultures contained 1 ÎĽm diameter filaments, some partially encrusted with iron oxides with visible cell walls, and others completely free of iron oxides, that are morphologically comparable to those preserved in the Rio Tinto rock record. Organic compounds (e.g. aliphatic hydrocarbons, amides and carboxylic acids) were detected at various levels within the culture and river terraces using mid-IR spectroscopy.
Rio Tinto is a natural laboratory allowing living cells to be studied and correlated to morphological and biomolecular fossils in the geological record. These deposits will provide predictive tools for biomarker studies that may be extended to analogous environments on ancient Earth or even Mars.
[1] Fernández-Remolar et al. (2005) Earth Planet Sci Lett 240,149-167.
[2] Fernández-Remolar & Knoll (2008) Icarus 194,72-85
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