165 results on '"Cockell C. S."'
Search Results
2. In Search of Future Earths: Assessing the possibility of finding Earth analogues in the later stages of their habitable lifetimes
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O'Malley-James, J. T., Greaves, J. S., Raven, J. A., and Cockell, C. S.
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Astrophysics - Earth and Planetary Astrophysics - Abstract
Earth will become uninhabitable within 2-3 Gyr as a result of the moving boundaries of the habitable zone caused by the increasing luminosity of the Sun. Predictions about the future of habitable conditions on Earth include a decline in species diversity and habitat extent, ocean loss and changes in the magnitudes of geochemical cycles. However, testing these predictions on the present-day Earth is difficult. The discovery of a planet that is a near analogue to the far future Earth could provide a means to test these predictions. Such a planet would need to have an Earth-like biosphere history, requiring it to have been in its system's habitable zone (HZ) for Gyr-long periods during the system's past, and to be approaching the inner-edge of the HZ at present. Here we assess the possibility of finding this very specific type of exoplanet and discuss the benefits of analysing older Earths in terms of improving our understanding of long-term geological and bio-geological processes. As an illustrative example, G stars within 10 parsecs are assessed as potential old-Earth-analogue hosts. Surface temperature estimates for hypothetical inner-HZ Earth analogues are used to determine whether any such planets in these systems would be at the right stage in their late-habitable lifetimes to exhibit detectable biosignatures. Predictions from planet formation studies and biosphere evolution models suggest that only 0.36% of G stars in the solar neighbourhood could host an old-Earth-analogue. However, if the development of an Earth-like biosphere is assumed to be rare, requiring a sequence of low-probability events to occur, then such planets are unlikely to be found in the solar neighbourhood - although 1000s could be present in the galaxy as a whole., Comment: Accepted for publication in Astrobiology
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- 2015
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3. Photosynthetic Potential of Planets in 3:2 Spin Orbit Resonances
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Brown, S. P., Mead, A. J., Forgan, D. H., Raven, J. A., and Cockell, C. S.
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Astrophysics - Earth and Planetary Astrophysics - Abstract
Photosynthetic life requires sufficient photosynthetically active radiation (PAR) to metabolise. On Earth, plant behaviour, physiology and metabolism are sculpted around the night-day cycle by an endogenous biological circadian clock. The evolution of life was influenced by the Earth-Sun orbital dynamic, which generates the photo-environment incident on the planetary surface. In this work the unusual photo-environment of an Earth-like planet (ELP) in 3:2 spin orbit resonance is explored. Photo-environments on the ELP are longitudinally differentiated, in addition to differentiations relating to latitude and depth (for aquatic organisms) which are familiar on Earth. The light environment on such a planet could be compatible with Earth's photosynthetic life although the threat of atmospheric freeze-out and prolonged periods of darkness would present significant challenges. We emphasise the relationship between the evolution of life on a planetary body with its orbital dynamics., Comment: 18 pages, 17 figures, accepted for publication in the International Journal of Astrobiology
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- 2014
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4. Swansong Biospheres: Refuges for life and novel microbial biospheres on terrestrial planets near the end of their habitable lifetimes
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O'Malley-James, J. T., Greaves, J. S., Raven, J. A., and Cockell, C. S.
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Astrophysics - Earth and Planetary Astrophysics - Abstract
The future biosphere on Earth (as with its past) will be made up predominantly of unicellular microorganisms. Unicellular life was probably present for at least 2.5 Gyr before multicellular life appeared and will likely be the only form of life capable of surviving on the planet in the far future, when the ageing Sun causes environmental conditions to become more hostile to more complex forms of life. Therefore, it is statistically more likely that habitable Earth-like exoplanets we discover will be at a stage in their habitable lifetime more conducive to supporting unicellular, rather than multicellular life. The end stage of habitability on Earth is the focus of this work. A simple, latitude-based climate model incorporating eccentricity and obliquity variations is used as a guide to the temperature evolution of the Earth over the next 3 Gyr. This allows inferences to be made about potential refuges for life, particularly in mountains and cold-trap (ice) caves and what forms of life could live in these environments. Results suggest that in high latitude regions, unicellular life could persist for up to 2.8 Gyr from present. This begins to answer the question of how the habitability of Earth will evolve at local scales alongside the Sun's main sequence evolution and, by extension, how the habitability of Earth-like planets would evolve over time with their own host stars., Comment: Accepted for publication in International Journal of Astrobiology
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- 2012
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5. Back to the Moon: The Scientific Rationale for Resuming Lunar Surface Exploration
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Crawford, I. A., Anand, M., Cockell, C. S., Falcke, H., Green, D. A., Jaumann, R., and Wieczorek, M. A.
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The lunar geological record has much to tell us about the earliest history of the Solar System, the origin and evolution of the Earth-Moon system, the geological evolution of rocky planets, and the near-Earth cosmic environment throughout Solar System history. In addition, the lunar surface offers outstanding opportunities for research in astronomy, astrobiology, fundamental physics, life sciences and human physiology and medicine. This paper provides an interdisciplinary review of outstanding lunar science objectives in all of these different areas. It is concluded that addressing them satisfactorily will require an end to the 40-year hiatus of lunar surface exploration, and the placing of new scientific instruments on, and the return of additional samples from, the surface of the Moon. Some of these objectives can be achieved robotically (e.g. through targeted sample return, the deployment of geophysical networks, and the placing of antennas on the lunar surface to form radio telescopes). However, in the longer term, most of these scientific objectives would benefit significantly from renewed human operations on the lunar surface. For these reasons it is highly desirable that current plans for renewed robotic surface exploration of the Moon are developed in the context of a future human lunar exploration programme, such as that proposed by the recently formulated Global Exploration Roadmap., Comment: Accepted for publication in a forthcoming Special Issue of Planetary and Space Science on "Scientific Preparations for Lunar Exploration"
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- 2012
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6. Light and Life: Exotic Photosynthesis in Binary Star Systems
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O'Malley-James, J. T., Raven, J. A., Cockell, C. S., and Greaves, J. S.
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
The potential for hosting photosynthetic life on Earth-like planets within binary/multiple stellar systems was evaluated by modelling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in: (i) close-binary systems; (ii) wide-binary systems and (iii) three-star systems were investigated and a range of stable radiation environments found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic forms of photosynthetic life, such as infrared photosynthesisers and organisms specialised for specific spectral niches., Comment: Accepted for publication in: Astrobiology
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- 2011
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7. Cryptic photosynthesis, Extrasolar planetary oxygen without a surface biological signature
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Cockell, C. S., Kaltenegger, L., and Raven, J. A.
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Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
On the Earth, photosynthetic organisms are responsible for the production of virtually all of the oxygen in the atmosphere. On the land, vegetation reflects in the visible, leading to a red edge that developed about 450 Myr ago and has been proposed as a biosignature for life on extrasolar planets. However, in many regions of the Earth, and particularly where surface conditions are extreme, for example in hot and cold deserts, photosynthetic organisms can be driven into and under substrates where light is still sufficient for photosynthesis. These communities exhibit no detectable surface spectral signature to indicate life. The same is true of the assemblages of photosynthetic organisms at more than a few metres depth in water bodies. These communities are widespread and dominate local photosynthetic productivity. We review known cryptic photosynthetic communities and their productivity. We link geomicrobiology with observational astronomy by calculating the disk-averaged spectra of cryptic habitats and identifying detectable features on an exoplanet dominated by such a biota. The hypothetical cryptic photosynthesis worlds discussed here are Earth-analogs that show detectable atmospheric biomarkers like our own planet, but do not exhibit a discernable biological surface feature in the disc-averaged spectrum., Comment: 23 pages, 2 figures, Astrobiology (TBP) - updated Table 1, typo in detectable O2 corrected
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- 2008
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8. DARWIN - A Mission to Detect, and Search for Life on, Extrasolar Planets
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Cockell, C. S., Leger, A., Fridlund, M., Herbst, T., Kaltenegger, L., Absil, O., Beichman, C., Benz, W., Blanc, M., Brack, A., Chelli, A., Colangeli, L., Cottin, H., Foresto, V. Coude du, Danchi, W., Defrere, D., Herder, J. -W. den, Eiroa, C., Greaves, J., Henning, T., Johnston, K., Jones, H., Labadie, L., Lammer, H., Launhardt, R., Lawson, P., Lay, O. P., LeDuigou, J. -M., Liseau, R., Malbet, F., Martin, S. R., Mawet, D., Mourard, D., Moutou, C., Mugnier, L., Paresce, F., Quirrenbach, A., Rabbia, Y., Raven, J. A., Rottgering, H. J. A., Rouan, D., Santos, N., Selsis, F., Serabyn, E., Shibai, H., Tamura, M., Thiebaut, E., Westall, F., White, and Glenn, J.
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Astrophysics - Abstract
The discovery of extra-solar planets is one of the greatest achievements of modern astronomy. The detection of planets with a wide range of masses demonstrates that extra-solar planets of low mass exist. In this paper we describe a mission, called Darwin, whose primary goal is the search for, and characterization of, terrestrial extrasolar planets and the search for life. Accomplishing the mission objectives will require collaborative science across disciplines including astrophysics, planetary sciences, chemistry and microbiology. Darwin is designed to detect and perform spectroscopic analysis of rocky planets similar to the Earth at mid-infrared wavelengths (6 - 20 micron), where an advantageous contrast ratio between star and planet occurs. The baseline mission lasts 5 years and consists of approximately 200 individual target stars. Among these, 25 to 50 planetary systems can be studied spectroscopically, searching for gases such as CO2, H2O, CH4 and O3. Many of the key technologies required for the construction of Darwin have already been demonstrated and the remainder are estimated to be mature in the near future. Darwin is a mission that will ignite intense interest in both the research community and the wider public.
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- 2008
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9. Radiative Habitable Zones in Martian Polar Environments
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Cordoba-Jabonero, C., Zorzano, M. -P., Selsis, F., Patel, M. R., and Cockell, C. S.
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Astrophysics - Abstract
The biologically damaging solar ultraviolet (UV) radiation (quantified by the DNA-weighted dose) reaches the Martian surface in extremely high levels. Searching for potentially habitable UV-protected environments on Mars, we considered the polar ice caps that consist of a seasonally varying CO2 ice cover and a permanent H2O ice layer. It was found that, though the CO2 ice is insufficient by itself to screen the UV radiation, at 1 m depth within the perennial H2O ice the DNA-weighted dose is reduced to terrestrial levels. This depth depends strongly on the optical properties ofthe H2O ice layers (for instance snow-lile layes). The Earth-like DNA-weighted dose and Photosynthetically Active Radiation (PAR) requirements were used to define the upper and lower limits of the nortern and southern polar radiative habitable zone (RHZ) for which a temporal and spatial mapping was performed. Based on these studies we conclude that phtosynthetic life might be possible within the ice layers of the polar regions. The thickness varies along each Martian polar spring and summer between 1.5 m and 2.4 m for H2= ice-like layers, and a few centimeters for snow-like covers. These Martian Earth-like radiative habitable environments may be primary targets for future Martian astrobiological missions. Special attention should be paid to planetary protection, since the polar RHZ may also be subject to terrestrial contamination by probes., Comment: 44 pages, 8 figures
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- 2005
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10. Aeolian abrasion of rocks as a mechanism to produce methane in the Martian atmosphere
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Safi, E., Telling, J., Parnell, J., Chojnacki, M., Patel, M. R., Realff, J., Blamey, N. J. F., Payler, S., Cockell, C. S., Davies, L., Boothroyd, I. M., Worrall, F., and Wadham, J. L.
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- 2019
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11. Deep Drilling into the Chesapeake Bay Impact Structure
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Gohn, G. S., Koeberl, C., Miller, K. G., Reimold, W. U., Browning, J. V., Cockell, C. S., Horton, J. W., Kenkmann, T., Kulpecz, A. A., Powars, D. S., Sanford, W. E., and Voytek, M. A.
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- 2008
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12. A steeply-inclined trajectory for the Chicxulub impact
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Collins, G. S., Patel, N., Davison, T. M., Rae, A. S. P., Morgan, J. V., Gulick, S. P. S., Christeson, G. L., Chenot, E., Claeys, P., Cockell, C. S., Coolen, M. J. L., Ferrière, L., Gebhardt, C., Goto, K., Jones, H., Kring, D. A., Lofi, J., Lowery, C. M., Ocampo-Torres, R., Perez-Cruz, L., Pickersgill, A. E., Poelchau, M. H., Rasmussen, C., Rebolledo-Vieyra, M., Riller, U., Sato, H., Smit, J., Tikoo, S. M., Tomioka, N., Urrutia-Fucugauchi, J., Whalen, M. T., Wittmann, A., Xiao, L., Yamaguchi, K. E., Artemieva, N., Bralower, T. J., Geology and Geochemistry, Department of Earth Science and Engineering [Imperial College London], Imperial College London, Institut de chimie et procédés pour l'énergie, l'environnement et la santé (ICPEES), Université de Strasbourg (UNISTRA)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), and Natural Environment Research Council (NERC)
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010504 meteorology & atmospheric sciences ,Science ,Impact angle ,General Physics and Astronomy ,010502 geochemistry & geophysics ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Impact crater ,EMPLACEMENT ,DEFORMATION ,CRATER ,10. No inequality ,lcsh:Science ,0105 earth and related environmental sciences ,Multidisciplinary ,Science & Technology ,Plane (geometry) ,ORIGIN ,METEORITE ,General Chemistry ,ANGLE ,Multidisciplinary Sciences ,BOUNDARY ,SIZE ,Meteorite ,PEAK-RING FORMATION ,13. Climate action ,Asteroid ,[SDU]Sciences of the Universe [physics] ,ASYMMETRY ,Trajectory ,Science & Technology - Other Topics ,lcsh:Q ,Third-Party Scientists ,IODP-ICDP Expedition 364 Science Party ,Asteroids, comets and Kuiper belt ,Seismology ,Geology - Abstract
The environmental severity of large impacts on Earth is influenced by their impact trajectory. Impact direction and angle to the target plane affect the volume and depth of origin of vaporized target, as well as the trajectories of ejected material. The asteroid impact that formed the 66 Ma Chicxulub crater had a profound and catastrophic effect on Earth’s environment, but the impact trajectory is debated. Here we show that impact angle and direction can be diagnosed by asymmetries in the subsurface structure of the Chicxulub crater. Comparison of 3D numerical simulations of Chicxulub-scale impacts with geophysical observations suggests that the Chicxulub crater was formed by a steeply-inclined (45–60° to horizontal) impact from the northeast; several lines of evidence rule out a low angle (, The authors here present a 3D model that simulates the formation of the Chicxulub impact crater. Based on asymmetries in the subsurface structure of the Chicxulub crater, the authors diagnose impact angle and direction and suggest a steeply inclined (60° to horizontal) impact from the northeast.
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- 2020
13. Description of Tessaracoccus profundi sp.nov., a deep-subsurface actinobacterium isolated from a Chesapeake impact crater drill core (940 m depth)
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Finster, K. W., Cockell, C. S., Voytek, M. A., Gronstal, A. L., and Kjeldsen, K. U.
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- 2009
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14. What makes a planet habitable?
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Lammer, H., Bredehöft, J. H., Coustenis, A., Khodachenko, M. L., Kaltenegger, L., Grasset, O., Prieur, D., Raulin, F., Ehrenfreund, P., Yamauchi, M., Wahlund, J.-E., Grießmeier, J.-M., Stangl, G., Cockell, C. S., Kulikov, Yu. N., Grenfell, J. L., and Rauer, H.
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- 2009
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15. THE VALUE OF HUMANS IN THE BIOLOGICAL EXPLORATION OF SPACE
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COCKELL, C. S.
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- 2004
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16. A bioenergetic model to predict habitability, biomass and biosignatures in astrobiology and extreme conditions
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Higgins, P. M., primary and Cockell, C. S., additional
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- 2020
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17. Ellsworth Subglacial Lake, West Antarctica: A review of its history and recent field campaigns
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Ross, N., primary, Siegert, M. J., additional, Rivera, A., additional, Bentley, M. J., additional, Blake, D., additional, Capper, L., additional, Clarke, R., additional, Cockell, C. S., additional, Corr, H. F. J., additional, Harris, W., additional, Hill, C., additional, Hindmarsh, R. C. A., additional, Hodgson, D. A., additional, King, E. C., additional, Lamb, H., additional, Maher, B., additional, Makinson, K., additional, Mowlem, M., additional, Parnell, J., additional, Pearce, D. A., additional, Priscu, J., additional, Smith, A. M., additional, Tait, A., additional, Tranter, M., additional, Wadham, J. L., additional, Whalley, W. B., additional, and Woodward, J., additional
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- 2011
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18. UV radiation and potential biological effects beneath the perennial ice cover of an antarctic lake
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Kepner, Jr., R. L., Wharton, Jr., R. A., Collier, R. D., Cockell, C. S., and Jeffrey, W. H.
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- 2000
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19. Ocean resurge-induced impact melt dynamics on the peak-ring of the Chicxulub impact structure, Mexico.
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Schulte, Felix M., Wittmann, Axel, Jung, Stefan, Morgan, Joanna V., Gulick, Sean P. S., Kring, David A., Grieve, Richard A. F., Osinski, Gordon R., Riller, Ulrich, IODP-ICDP Expedition 364 Science Party, Gulick, S. P. S., Morgan, J. V., Bralower, T. J., Chenot, E., Christeson, G. L., Claeys, P., Cockell, C. S., Coolen, M. J. L., Ferrière, L., and Gebhardt, C.
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KELVIN-Helmholtz instability ,RAYLEIGH-Taylor instability ,CLAY minerals ,OCEAN ,MELTING ,BRECCIA ,MARINE debris - Abstract
Core from Hole M0077 from IODP/ICDP Expedition 364 provides unprecedented evidence for the physical processes in effect during the interaction of impact melt with rock-debris-laden seawater, following a large meteorite impact into waters of the Yucatán shelf. Evidence for this interaction is based on petrographic, microstructural and chemical examination of the 46.37-m-thick impact melt rock sequence, which overlies shocked granitoid target rock of the peak ring of the Chicxulub impact structure. The melt rock sequence consists of two visually distinct phases, one is black and the other is green in colour. The black phase is aphanitic and trachyandesitic in composition and similar to melt rock from other sites within the impact structure. The green phase consists chiefly of clay minerals and sparitic calcite, which likely formed from a solidified water–rock debris mixture under hydrothermal conditions. We suggest that the layering and internal structure of the melt rock sequence resulted from a single process, i.e., violent contact of initially superheated silicate impact melt with the ocean resurge-induced water–rock mixture overriding the impact melt. Differences in density, temperature, viscosity, and velocity of this mixture and impact melt triggered Kelvin–Helmholtz and Rayleigh–Taylor instabilities at their phase boundary. As a consequence, shearing at the boundary perturbed and, thus, mingled both immiscible phases, and was accompanied by phreatomagmatic processes. These processes led to the brecciation at the top of the impact melt rock sequence. Quenching of this breccia by the seawater prevented reworking of the solidified breccia layers upon subsequent deposition of suevite. Solid-state deformation, notably in the uppermost brecciated impact melt rock layers, attests to long-term gravitational settling of the peak ring. [ABSTRACT FROM AUTHOR]
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- 2021
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20. Stress‐Strain Evolution During Peak‐Ring Formation: A Case Study of the Chicxulub Impact Structure
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Rae, Auriol, Collins, Gareth, Poelchau, Michael, Riller, Ulrich, Davison, Thomas, Grieve, Richard, Osinski, Gordon, Morgan, Joanna, Gulick, S. P. S., Chenot, Elise, Christeson, G. L., Claeys, P., Cockell, C. S., Coolen, M. J. L., Ferrière, L., Gebhardt, C., Goto, K., Green, S., Jones, H., Kring, D. A., Lofi, Johanna, Lowery, C. M., Ocampo‐Torres, R., Perez‐Cruz, L., Pickersgill, A. E., Rasmussen, C., Rae, A.S.P., Rebolledo‐Vieyra, M., Sato, H., Smit, J., Tikoo, S. M., Tomioka, N., Urrutia‐Fucugauchi, J., Whalen, M. T., Wittmann, A., Xiao, L., Yamaguchi, K. E., Department of Earth Science and Engineering [Imperial College London], Imperial College London, University of Freiburg [Freiburg], Universität Hamburg (UHH), Centre for Planetary Science and Exploration [London, ON] (CPSX), University of Western Ontario (UWO), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), and Natural Environment Research Council (NERC)
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Geochemistry & Geophysics ,010504 meteorology & atmospheric sciences ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,01 natural sciences ,stress ,strain ,Impact crater ,DEFORMATION ,FLUIDIZATION ,Geochemistry and Petrology ,impact cratering ,CRATER ,Earth and Planetary Sciences (miscellaneous) ,Fluidization ,Impact structure ,Petrology ,0105 earth and related environmental sciences ,Science & Technology ,ORIGIN ,Scientific drilling ,Stress–strain curve ,deformation ,Drilling ,International Ocean Discovery Program ,peak ring ,Geophysics ,Chicxulub ,Shear (geology) ,13. Climate action ,Space and Planetary Science ,Physical Sciences ,ASYMMETRY ,MOON ,Geology ,HYDROCODE SIMULATIONS - Abstract
Deformation is a ubiquitous process that occurs to rocks during impact cratering; thus, quantifying the deformation of those rocks can provide first-order constraints on the process of impact cratering. Until now, specific quantification of the conditions of stress and strain within models of impact cratering has not been compared to structural observations. This paper describes a methodology to analyze stress and strain within numerical impact models. This method is then used to predict deformation and its cause during peak-ring formation: a complex process that is not fully understood, requiring remarkable transient weakening and causing a significant redistribution of crustal rocks. The presented results are timely due to the recent Joint International Ocean Discovery Program and International Continental Scientific Drilling Program drilling of the peak ring within the Chicxulub crater, permitting direct comparison between the deformation history within numerical models and the structural history of rocks from a peak ring. The modeled results are remarkably consistent with observed deformation within the Chicxulub peak ring, constraining the following: (1) the orientation of rocks relative to their preimpact orientation; (2) total strain, strain rates, and the type of shear during each stage of cratering; and (3) the orientation and magnitude of principal stresses during each stage of cratering. The methodology and analysis used to generate these predictions is general and, therefore, allows numerical impact models to be constrained by structural observations of impact craters and for those models to produce quantitative predictions.Plain Language Summary During impact cratering events, extreme forces act on rocks beneath the crater to produce deformation. Computer simulations of large impact cratering events are particularly important because the conditions of those events can never be simultaneously produced by laboratory experiments. In this study, we describe a method by which the forces and deformations that occur during cratering can be measured in computer simulations of impact cratering events. Combining this analysis with geological observations from impact structures allows us to improve our understanding of impact crater formation. Here, we use this method to study the Chicxulub impact structure, Mexico, to understand the formation of peak rings, rings of hills found internal to the rim of large impact craters. Our analysis provides estimates of the sequence of forces and deformation during peak-ring formation. As deformation produces fractures, our analysis has important implications for how fluids flow through rocks in craters.
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- 2019
21. Scientific Goals and Objectives for the Human Exploration of Mars: 1. Biology and Atmosphere/Climate
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Levine, Joel S, Garvin, J. B, Anbar, A. D, Beaty, D. W, Bell, M. S, Clancy, R. T, Cockell, C. S, Connerney, J. E, Doran, P. T, Delory, G, Dickson, J. T, Elphic, R. C, Eppler, D. B, Fernandez-Remolar, D. C, Head, J. W, Helper, M, Gruener, J. E, Heldmann, J, Hipkin, V, Lane, M. D, Levy, J, Moersch, J, Ori, G. G, Peach, L, and Poulet, F
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Lunar And Planetary Science And Exploration - Abstract
To prepare for the exploration of Mars by humans, as outlined in the new national vision for Space Exploration (VSE), the Mars Exploration Program Analysis Group (MEPAG), chartered by NASA's Mars Exploration Program (MEP), formed a Human Exploration of Mars Science Analysis Group (HEM-SAG), in March 2007. HEM-SAG was chartered to develop the scientific goals and objectives for the human exploration of Mars based on the Mars Scientific Goals, Objectives, Investigations, and Priorities.1 The HEM-SAG is one of several humans to Mars scientific, engineering and mission architecture studies chartered in 2007 to support NASA s plans for the human exploration of Mars. The HEM-SAG is composed of about 30 Mars scientists representing the disciplines of Mars biology, climate/atmosphere, geology and geophysics from the U.S., Canada, England, France, Italy and Spain. MEPAG selected Drs. James B. Garvin (NASA Goddard Space Flight Center) and Joel S. Levine (NASA Langley Research Center) to serve as HEMSAG co-chairs. The HEM-SAG team conducted 20 telecons and convened three face-to-face meetings from March through October 2007. The management of MEP and MEPAG were briefed on the HEM-SAG interim findings in May. The HEM-SAG final report was presented on-line to the full MEPAG membership and was presented at the MEPAG meeting on February 20-21, 2008. This presentation will outline the HEM-SAG biology and climate/atmosphere goals and objectives. A companion paper will outline the HEM-SAG geology and geophysics goals and objectives.
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- 2008
22. THE VALUE OF HUMANS IN THE BIOLOGICAL EXPLORATION OF SPACE
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COCKELL, C. S.
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- 2005
23. Microbial Preservation in Sulfates in the Haughton Impact Structure Suggests Target in Search for Life on Mars
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Parnell, J, Osinski, G. R, Lee, P, and Cockell, C. S
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Lunar And Planetary Science And Exploration - Abstract
Microbes in Haughton Crater Sulfates: Impact craters are of high interest in planetary exploration because they are viewed as possible sites for evidence of life [1]. Hydrothermal systems in craters are particularly regarded as sites where primitive life could evolve. Evidence from the Miocene Haughton impact structure shows that crater hydrothermal deposits may also be a preferred site for subsequent colonization and hence possible extant life: Hydrothermal sulfates at Haughton are colonized by viable cyanobacteria [2]. The Haughton impact structure, Devon Island, Canadian High Arctic, is a 24 km-diameter crater of mid-Tertiary age. The structure preserves an exceptional record of impact-induced hydrothermal activity, including sulfide, and sulfate mineralization [3]. The target rocks excavated at the site included massive gypsum-bearing carbonate rocks of Ordovician age. Impact-remobilized sulfates occur as metre-scale masses of intergrown crystals of the clear form of gypsum selenite in veins and cavity fillings within the crater s impact melt breccia deposits [4]. The selenite is part of the hydrothermal assemblage as it was precipitated by cooling hot waters that were circulating as a result of the impact. Remobilization of the sulfate continues to the present day, such that it occurs in soil crusts (Fig. 1) including sandy beds with a gypsum cement. The sulfate-cemented beds make an interesting comparison with the sulfate-bearing sandy beds encountered by the Opportunity MER [5]. The selenite crystals are up to 0.3 m in width, of high purity, and transparent. They locally exhibit frayed margins where cleavage surfaces have separated. This exfoliation may be a response to freeze-thaw weathering. The selenite contains traces of rock detritus, newly precipitated gypsum, and microbial colonies. The rock detritus consists of sediment particles which penetrated the opened cleavages by up to 2cm from the crystal margins. Some of the detritus is cemented into place by gypsum, which must have been dissolved and reprecipitated from the host selenite.
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- 2005
24. Impact-shocked rocks--insights into Archean and extraterrestrial microbial habitats (and sites for prebiotic chemistry?)
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Cockell, C. S
- Subjects
Exobiology - Abstract
Impact-shocked gneiss shocked to greater than 10 GPa in the Haughton impact structure in the Canadian High Arctic has an approximately 25-times greater pore surface area than unshocked rocks. These pore spaces provide microhabitats for a diversity of heterotrophic microorganisms and in the near-surface environment of the rocks, where light levels are sufficient, cyanobacteria. Shocked rocks provide a moisture retaining, UV protected microenvironment. During the Archean, when impact fluxes were more than two orders of magnitude higher than today, the shocked-rock habitat was one of the most common terrestrial habitats and might have provided a UV-shielded refugium for primitive life. These potential habitats are in high abundance on Mars where impact crater habitats could have existed over geologic time periods of billions of years, suggesting that impact-shocked rocks are important sites to search for biomolecules in extraterrestrial life detection strategies. In addition to being favourable sites for life, during the prebiotic period of planetary history impact-shocked rocks might have acted as a site for the concentration of reactants for prebiotic syntheses. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.
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- 2004
25. Microbial Mats in the Tswaing Impact Crater: Results of a South African Exobiology Expedition and Implications for the Search for Biological Molecules on Mars
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Cockell, C. S, Brandt, D, Hand, K, and Lee, P. C
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Lunar And Planetary Science And Exploration - Abstract
We describe microbial mats from the Tswaing impact crater in South Africa. The mats provide insights into the unique biological characteristics of impact craters and can help strategies for the search for biomolecules on Mars. Additional information is contained in the original extended abstract.
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- 2001
26. Trace element biosignatures and the evolution of the metallome in Earth’s early oceans
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Hickman-Lewis, K., Sorieul, S., Gautret, P., Foucher, Frédéric, Georgelin, T., Cockell C., S., Westall, Frances, Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Vecteurs - Infections tropicales et méditerranéennes (VITROME), Institut de Recherche Biomédicale des Armées (IRBA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU), Institut Hospitalier Universitaire Méditerranée Infection (IHU Marseille), Frapart, Isabelle, Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut de Recherche Biomédicale des Armées [Brétigny-sur-Orge] (IRBA)
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[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2018
27. Influence of early ocean chemistry on cell biochemistry and prokaryotic metallomic biosignatures
- Author
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Hickman-Lewis, K., Cavalazzi, B., Sorieul, S., Gautret, P., Foucher, Frédéric, Georgelin, T., Cockell C., S., Westall, F., Frapart, Isabelle, Centre de biophysique moléculaire (CBM), and Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)
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[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2018
28. The ultraviolet environment of Mars: biological implications past, present, and future
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Cockell, C. S, Catling, D. C, Davis, W. L, Snook, K, Kepner, R. L, Lee, P, and McKay, C. P
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Lunar And Planetary Science And Exploration - Abstract
A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.
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- 2000
- Full Text
- View/download PDF
29. pH Influences the Distribution of Microbial Rock-Weathering Phenotypes in Weathered Shale Environments
- Author
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Samuels, T., primary, Pybus, D., additional, Wilkinson, M., additional, and Cockell, C. S., additional
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- 2019
- Full Text
- View/download PDF
30. Microbial Mayhem in the Nascent Chicxulub Crater
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Schaefer, B., primary, Grice, K., additional, Coolen, M.J.L., additional, Summons, R.E., additional, Cui, X., additional, Bauersachs, T., additional, Schwark, L., additional, Böttcher, M. E., additional, Bralower, T. J., additional, Lyons, S. L., additional, Freeman, K. H., additional, Cockell, C. S., additional, Gulick, S. S., additional, Morgan, J. V., additional, Whalen, M. T., additional, Lowery, C. M., additional, and Vajda, V., additional
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- 2019
- Full Text
- View/download PDF
31. Radiation: microbial evolution, ecology, and relevance to mars missions
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Rothschild, L. J and Cockell, C. S
- Subjects
Life Sciences (General) - Abstract
Ultraviolet (UV) radiation has been an important environmental parameter during the evolution of life on Earth, both in its role as a mutagen and as a selective agent. This was probably especially true during the time from 3.8 to 2.5 billion years ago, when atmospheric ozone levels were less than 1% of present levels. Early Mars may not have had an "ozone shield" either, and it never developed a significant one. Even though Mars is farther away from the Sun than the Earth, a substantial surficial UV flux is present on Mars today. But organisms respond to dose rate, and on Mars, like on Earth, organisms would be exposed to diurnal variations in UV flux. Here we present data on the effect of diurnal patterns of UV flux on microbial ecosystems in nature, with an emphasis on photosynthesis and DNA synthesis effects. These results indicate that diurnal patterns of metabolism occur in nature with a dip in photosynthesis and DNA synthesis in the afternoon, in part regulated by UV flux. Thus, diurnal patterns must be studied in order to understand the effect of UV radiation in nature. The results of this work are significant to the success of human missions to Mars for several reasons. For example, human missions must include photosynthetic organisms for food production and likely oxygen production. An evolutionary approach suggests which organisms might be best suited for high UV fluxes. The diurnal aspect of these studies is critical. Terraforming is a potential goal of Mars exploration, and it will require studies of the effect of Martian UV fluxes, including their diurnal changes, on terrestrial organisms. Such studies may suggest that diurnal changes in UV only require mitigation at some times of day or year.
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- 1999
- Full Text
- View/download PDF
32. Ultraviolet Radiation on the Surface of Mars
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Catling, D. C, Cockell, C. S, and McKay, C. P
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Lunar And Planetary Science And Exploration - Abstract
An evaluation of the ultraviolet (UV) flux incident on the Martian surface is important for a number of issues. UV-induced photolysis of water changes the chemistry of the soil and atmosphere, inducing its oxidizing nature. Alternatively, UV may directly affect surface chemistry by generating silicate defects. UV also rapidly degrades organic material delivered by meteoritic infall. Consequently, UV affects the overall chemistry of the Martian surface and atmosphere. The extent of UV breakdown of organic molecules is also relevant to concerns regarding contaminants on lander or rover surfaces that could interfere with life-detection experiments causing "false positives". The radiation flux at a point on the surface of Mars depends on factors such as cloud cover, atmospheric dust loading, season, local time, and latitude. Previously, the UV spectrum incident on the surface of Mars has been calculated from a simple radiative transfer model. Limitations of this earlier model include no accounting for the effect of dust, which may be a perennial constituent of the atmosphere, and also the use of gas absorption data measured at room temperature that overestimate absorption for lower Martian temperatures. We present an updated model for UV radiation (200-400 nm) that incorporates dust and more recent data for the solar spectrum, gas absorption, and UV surface albedo. Additional information is contained in the original extended abstract.
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- 1999
33. The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats
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Cockell, C. S and Rothschild, L. J
- Subjects
Life Sciences (General) - Abstract
Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.
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- 1999
- Full Text
- View/download PDF
34. The Polar Exploration of Mars
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Cockell, C. S
- Subjects
Lunar And Planetary Exploration - Abstract
Apart from the Earth, Mars is the only planet in our Solar System to possess significant and traversable polar caps that could potentially play host to a long term program of human polar exploration. Such explorations may provide valuable information on the structure of the martian poles, both geologically and from the point of view of gaining an increased insight into volatile cycling in the martian atmosphere, past and present. Here some initial considerations are made on the nature and methods for the human exploration of the martian poles and the scientific objectives that might be prioritized for such missions. The first proposed strategies and routes for overland Mars polar expeditions, using the nature of terrestrial polar expedition attempts as a template, are also suggested.
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- 1997
35. Occurrence and significance of carbonaceous matter at the surface of Mars
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Hickman-Lewis, K., Gautret, P., Foucher, Frédéric, Cavalazzi, B., Cockell C., S., Westall, F., the MASE, Team, Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Vecteurs - Infections tropicales et méditerranéennes (VITROME), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut de Recherche Biomédicale des Armées [Brétigny-sur-Orge] (IRBA), Frapart, Isabelle, Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and Institut de Recherche Biomédicale des Armées (IRBA)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)
- Subjects
[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,[CHIM] Chemical Sciences ,[CHIM]Chemical Sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2017
36. Mars exploration begins on Earth: Systematic comparison of the anaerobic, intact and cultivable microbiome of extreme, anoxic, Mars-analogue environments
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Perras A., K., Wink, L., Duller, S., Monaghan, E., Schwendner, P., Cockell C., S., Rettberg, P., Beblo-Vranesevic, K., Bohmeier, M., Gaboyer, F., Westall, F., Walter, N., Cabezas P. Garcia-Descalzo, L., Gomez, F., Malki, M., Amils, R., Ehrenfreund, P., Vannier, P., Marteinsson, V., Erlacher, A, Mahnert, A., Bashir, M., Moissl-Eichinger, C., Leiden Observatory [Leiden], Universiteit Leiden [Leiden], UK Centre for Astrobiology, SUPA School of Physics and Astronomy [Edinburgh], University of Edinburgh-University of Edinburgh, DLR Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt [Köln] (DLR), Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), European Science Foundation (ESF), Centro de Astrobiologia [Madrid] (CAB), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), Universidad Autonoma de Madrid (UAM), and Frapart, Isabelle
- Subjects
[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,[CHIM] Chemical Sciences ,[CHIM]Chemical Sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2017
37. Mineralization and Preservation of an extremotolerant Bacterium Isolated from an Early Mars Analog Environment
- Author
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Gaboyer, F., Le Milbeau, C., Bohmeier, M., Schwendner, P., Vannier, P., Beblo-Vranesevic, K., Rabbow, E., Foucher, F., Gautret, P., Guégan, R., Richard, A., Sauldubois, A., Richmann, P., Perras, A. K., Moissl-Eichinger, C., Cockell, C. S., Rettberg, P., Marteinsson, Monaghan, E., Ehrenfreund, P., Garcia-Descalzo, L., Gomez, F., Malki, M., Amils, R., Cabezas, P., Walter, N., Westall, F., Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Biogéosystèmes Continentaux - UMR7327, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), DLR Institute of Aerospace Medicine, Deutsches Zentrum für Luft- und Raumfahrt [Köln] (DLR), UK Centre for Astrobiology, SUPA School of Physics and Astronomy [Edinburgh], University of Edinburgh-University of Edinburgh, MATIS - Prokaria, Centre de Microscopie Electronique, Université d'Orléans (UO), Universität Regensburg (UR), BioTechMed-Graz, Graz University of Technology [Graz] (TU Graz)-Karl-Franzens-Universität [Graz, Autriche]-Medical University Graz, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Universidad Autonoma de Madrid (UAM), European Science Foundation (ESF), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Graz University of Technology [Graz] (TU Graz)-Karl-Franzens-Universität Graz-Medical University Graz, Universidad Autónoma de Madrid (UAM), POTHIER, Nathalie, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), and Graz University of Technology [Graz] (TU Graz)-Medical University Graz-Karl-Franzens-Universität [Graz, Autriche]
- Subjects
EXTREMOPHILIC ARCHAEA ,Science ,EXPERIMENTAL SILICIFICATION ,MERIDIANI-PLANUM ,Mars ,BLUE-GREEN-ALGAE ,Article ,EXPERIMENTAL DIAGENESIS ,[SDU] Sciences of the Universe [physics] ,Strahlenbiologie ,RAMAN-SPECTROSCOPY ,[SDU]Sciences of the Universe [physics] ,EXPERIMENTAL FOSSILIZATION ,MASE project (Mars Analogue for Space Exploration) ,Medicine ,ARCHEAN CHERTS ,MOLECULAR PRESERVATION ,ATACAMA DESERT - Abstract
International audience; The artificial mineralization of a polyresistant bacterial strain isolated from an acidic, oligotrophic lake was carried out to better understand microbial (i) early mineralization and (ii) potential for further fossilisation. Mineralization was conducted in mineral matrixes commonly found on Mars and Early-Earth, silica and gypsum, for 6 months. Samples were analyzed using microbiological (survival rates), morphological (electron microscopy), biochemical (GC-MS, Microarray immunoassay, Rock-Eval) and spectroscopic (EDX, FTIR, RAMAN spectroscopy) methods. We also investigated the impact of physiological status on mineralization and long-term fossilisation by exposing cells or not to Mars-related stresses (desiccation and radiation). Bacterial populations remained viable after 6 months although the kinetics of mineralization and cell-mineral interactions depended on the nature of minerals. Detection of biosignatures strongly depended on analytical methods, successful with FTIR and EDX but not with RAMAN and immunoassays. Neither influence of stress exposure, nor qualitative and quantitative changes of detected molecules were observed as a function of mineralization time and matrix. Rock-Eval analysis suggests that potential for preservation on geological times may be possible only with moderate diagenetic and metamorphic conditions. The implications of our results for microfossil preservation in the geological record of Earth as well as on Mars are discussed. Redrawing the history of early life on Earth requires being able to assess if microstructures present in the oldest terrestrial rocks are of biological origin or not. Such assessments are still very challenging mainly due to the degradation of microbial remains during diagenesis and to microbial-like morphologies abiotically produced. Several Archaean rocks could nevertheless be described as ancient unambiguous biological systems, representative of the early-Earth fossil record, like strata of South Africa and Australia containing evidence of phototrophic 1–6 and heterotrophic microbial. To better understand the processes leading to microfossil formation and preservation, artificial mineralization of microorganisms, also called fossilisation, was first undertaken by Oehler and Schopf with the silicification of
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- 2017
38. Metabolic response of Yersinia intermedia MASE-LG1 to osmotic stress
- Author
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Schwendner, P., Cockell, C. S., Perras, A., Rettberg, Petra, Beblo-Vranesevic, Kristina, Bohmeier, M., Moissl-Eichinger, C., Marteinsson, V., Vannier, P., Gomez, F., Garcia-Descalzo, L., Ehrenfreund, P., Monaghan, E. P., Westall, F., Gaboyer, F., Amils, R., Malki, M., Cabezas, P., and Walter, N.
- Subjects
Strahlenbiologie ,Yersinia intermedia MASE-LG1 ,osmotic stress - Abstract
Osmotic stress is one of the major limitations for cell growth. Microorganisms can evolve adaptations to abiotic stresses like high salt concentrations in the environment. Sensor and signal transduction networks provide information to the cell about the osmolarity of its surroundings leading to an immediate metabolic response to counteract the osmotic stress. Some of these adaptations can be structural, some are metabolic. Our current knowledge of microbial responses to osmotic challenges is based on studies of representative bacteria, archaea, and eukaryotic microbes that is mainly focusing on the effect of NaCl. There is still a lack of understanding whether and how different salts, for example NaCl versus MgSO4 alter the response of a microorganism to salt induced stress conditions. We chose Yersinia intermedia MASE-LG1 a strain isolated from an Icelandic lake as test organism. It is known for its abilities to adapt to a wide variety of habitats of rapidly changing environmental conditions. In order to identify which roles the different salts play in the global metabolic response, Y. intermedia was exposed sustained salt stress induced by either MgSO4 or NaCl. After metabolite extraction, metabolic profiles from three replicate cultures of Y. intermedia MASE-LG-1 grown under 3 different conditions (e.g. control salt stressed in MgSO4, and salt stressed in NaCl) were obtained. Generally, changes in numerous metabolites mainly in the amino acid metabolisms were observed in stressed samples compared to the control. To a lesser extent the carbohydrate metabolism was also affected. Looking at the effect of the different kations, the results clearly indicated significant differences in response to salt stress induced by the magnesium salt compared to sodium chloride. The results suggest that the amino acid synthesis, reflecting the general activity of translation operations, dominates the reaction to osmotic stress. These adaptations might provide necessary energy and building blocks to fuel processes conveying salt tolerance like the biosynthesis of compatible solutes. In addition we were able to identify metabolites which are linked to osmoprotective activity. The outcome of this study will have impact on our understanding of how microorganisms adapt to hostile environmental conditions.
- Published
- 2017
39. Mars Analogues for space exploration – A summary of results
- Author
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Cockell, C. S. (and the MASE Team)
- Subjects
Strahlenbiologie ,MASE (Mars Analogues for Space Exploration) - Abstract
Astrobiology seeks to understand the limits of life and to determine the physiology of organisms in order to be able to better assess the potential habitability of other worlds and improve our ability to assay them for the presence of life. To successfully achieve this we require representative microorganisms from environments on Earth that in physical and/or chemical conditions approximate to extraterrestrial environments. The most challenging of these environ-ments with respect to the sample collection and follow on isolation and cultivation of microorganisms are anaerobic environments. Here we describe a systematic approach to this challenge and aim to provide a guideline for future field work and sampling campaigns. We selected a number of anaerobic environments based on characteristics that make them analogous to past and present locations on Mars (Icelandic lakes, sulfidic springs, deep hypersaline environ-ments, acidic iron-rich environments and permafrost). We implemented a culturing approach to enrich organisms from these environments under anaerobic conditions using a defined medium that would allow for all organisms to be grown under iden- tical culturing conditions in future physiological comparisons. We then isolated anaerobic microorganisms, carried out a study of their basic physiology and deposited these organisms in the DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH) culture collection to make them available to astrobiologists and microbiologists. These organisms can them be used for a variety of astrobiology projects. In MASE, the selected organisms are being artifically fossilised and matured and the ensuing biosignatures studied in order to aid the search for in situ biosignatures on Mars and in samples returned from Mars. This project represents the first attempt to implement a coordinated effort from the selection of extraterrestrial analog sites through to the isolation and the characterisation of organisms and their deposition within a culture collection.
- Published
- 2017
40. Hydrothermal chemotrophic biosignatures on Mars
- Author
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Westall, F., Campbell K., A., Gautret, P., Bréhéret, J., Foucher, Frédéric, Vago, J.-L., Kminek, G, Hickman Lewis, K., Cockell C., S., Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and Frapart, Isabelle
- Subjects
[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2016
41. Hydrothermal chemotrophic biosignatures on Mars
- Author
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Westall, Frances, Campbell K., A., Gautret, P., Bréhéret, J., Foucher, Frédéric, Gaboyer, F., Vago J., L., Kminek, G., Hubert, A., Hickman-Lewis, K., Cockell C., S., Centre de biophysique moléculaire (CBM), Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR48, Institut des sciences biologiques (INSB-CNRS)-Institut des sciences biologiques (INSB-CNRS)-Centre National de la Recherche Scientifique (CNRS), Frapart, Isabelle, Université d'Orléans (UO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and INSB-INSB-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU] Sciences of the Universe [physics] ,[SDU]Sciences of the Universe [physics] ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2016
42. Anaerobic microorganisms in astrobiological analogue environments: from field site to culture collection
- Author
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Cockell, C. S., primary, Schwendner, P., additional, Perras, A., additional, Rettberg, P., additional, Beblo-Vranesevic, K., additional, Bohmeier, M., additional, Rabbow, E., additional, Moissl-Eichinger, C., additional, Wink, L., additional, Marteinsson, V., additional, Vannier, P., additional, Gomez, F., additional, Garcia-Descalzo, L., additional, Ehrenfreund, P., additional, Monaghan, E.P., additional, Westall, F., additional, Gaboyer, F., additional, Amils, R., additional, Malki, M., additional, Pukall, R., additional, Cabezas, P., additional, and Walter, N., additional
- Published
- 2017
- Full Text
- View/download PDF
43. Lunar Mission One: The First Crowdfunded Mission to the Moon Presenting New Opportunities for Lunar Science
- Author
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Anand, M., Crawford, I. A., Sims, M. R., Smith, A., Burgess, R., Katherine Joy, Cockell, C. S., Sephton, M. A., Russell, S. S., Smith, C. L., Smith, D. J., Woan, G., Bowles, N., Grady, M. M., Zarnecki, J. C., and Iron, D.
- Published
- 2015
- Full Text
- View/download PDF
44. Lunar Mission One: the first crowdfunded mission to the Moon presenting new opportunities for lunar science
- Author
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Anand M., Crawford I. A., Sims M. R., Smith A., Burgess R., Joy K. H., Cockell C. S., Sephton M. A., Russell S. S., Smith C. L., Smith D. J., Woan G., Bowles N., Grady M. M., Zarnecki J. C., and Iron D.
- Published
- 2015
45. Anaerobic microorganisms in astrobiological analogue environments: from field site to culture collection.
- Author
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Cockell, C. S., Schwendner, P., Perras, A., Rettberg, P., Beblo-Vranesevic, K., Bohmeier, M., Rabbow, E., Moissl-Eichinger, C., Wink, L., Marteinsson, V., Vannier, P., Gomez, F., Garcia-Descalzo, L., Ehrenfreund, P., Monaghan, E.P., Westall, F., Gaboyer, F., Amils, R., Malki, M., and Pukall, R.
- Published
- 2018
- Full Text
- View/download PDF
46. Raman spectroscopy of amino acids and other biomarkers on Mars
- Author
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Rolfe, S. M., Patel, M. R., Olsson-Francis, K., Cockell, C. S., and Ringrose, T. J.
- Abstract
In the search for life elsewhere in the Solar System, our nearest planetary neighbour, Mars, offers great potential for finding past or present life. Whether life is extant or not, signs of biological activity can be inferred through the detection of specific biomarkers, such as amino acids.\ud \ud Raman spectroscopy is an extremely effective method of detecting biomarkers. It is non-destructive and is used to identify different molecular species through observations of the Raman shift created by the bonds within the molecule.\ud \ud Amino acids that are part of a biological system could provide potential evidence of life on Mars. It is thought that amino acids could survive in the sub-surface of Mars, making them a high-priority biomarker candidate. Terrestrial life utilises homochiral amino acids, and if detected on Mars it would provide an important piece of evidence for the case for life on Mars.\ud \ud In this work, a number of biologically essential amino acids that are utilised in terrestrial organisms will be studied using Raman spectroscopy. We aim to characterise the Raman signature for these molecules in detail in order to aid interpretation of results from future Mars landers, and presented here are initial results from the preliminary investigations. \ud \ud Further work will extend to other high-priority biomarkers that may be found at the surface/sub-surface of Mars.
- Published
- 2011
47. STONE 6: Artificial Sedimentary Meteorites in Space
- Author
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Westall, F., Demets, R., Brandstetter, F., Edwards, H. G. M., Cockell, C. S., Parnell, J., Pillinger, J., Sancisi-Frey, S., Franchi, I. A., Kurat, G., and Brack, A.
- Abstract
The STONE 6 experiment demonstrated the survivability of carbonaceous and microfossiliferous martian analogue sediments during atmospheric re-entry. Doped endoliths died but their carbonised cells remained.
- Published
- 2008
48. Impact pressures generated by spherical particle hypervelocity impact on Yorkshire Sandstone
- Author
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Miljkovic, K., Taylor, E. A., Tsembelis, K., Proud, W. G., Cockell, C. S., and Zarnecki, J. C.
- Published
- 2007
49. The influence of shock pressure, pre-shock temperature, and host rock composition on the survival rate of endolithic microorganisms during impact ejection from Mars
- Author
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Misgaiski, M., Meyer, C., Stöffler, D., Fritz, J., Horneck, G., Moeller, R., Rabbow, E., Cockell, C. S., De Vera, J. P., Ott, S., and Hornemann, U.
- Abstract
Petrographic and biological analysis of shock recovery experiments confirms the possible life transport due to an impact from Mars to Earth.
- Published
- 2007
50. Life after shock: the mission from Mars to Earth
- Author
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Meyer, C., Stöffler, D., Fritz, J., Horneck, G., Möller, R., Cockell, C. S., de Vera, J. P., and Hornemann, U.
- Abstract
Extract from introduction: The minerals of the Martian meteorites collected so far indicate an exposure to shock waves in the pressure range of 5 to 55 GPa [1]. As terrestrial rocks are frequently inhabited by microbial communities, rocks ejected from a planet by impact processes may carry with them endolithic microorganisms, if microbial life existed/exists on this planet.
- Published
- 2006
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