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Sorted by: Date Added To NTRS in Descending order 1 2 3 Next  Earth After the Moon Forming Impact Author(s): Zahnle, Kevin Abstract: The Hadean Earth is widely and enduringly pictured as a world of exuberant volcanism, exploding meteors, huge craters, infernal heat, and billowing sulfurous steams; i.e., a world of fire and brimstone punctuated with blows ... NASA Center: Ames Research Center Publication Year: 2006 Added to NTRS: 2006-12-20 Document ID: 20060054214 Sulfur during the Transition from Anoxic to Oxic Atmospheres Author(s): Zahnle, Kevin; Catling, David; Claire, Mark Abstract: The invention of oxygenic photosynthesis was likely accompanied by the introduction of large amounts of O2 and complementary reduced gases (chiefly CH4) into the atmosphere. To first approximation the venting of O2 and CH4 ... NASA Center: Ames Research Center Publication Year: 2006 Added to NTRS: 2006-09-29 Document ID: 20060021472 Hydrodynamic Simulations of Asteroid Impacts on Venus Author(s): Zahnle, Kevin; Korycansky, Donald G. Abstract: In this study, numerous two-dimensional (2-D) high-resolution hydrodynamical simulations of asteroids striking the atmosphere of Venus were performed. The computations used ZEUS, a grid- based Eulerian hydro-code designed to ... NASA Center: Ames Research Center Publication Year: 2000 Added to NTRS: 2005-11-24 Document ID: 20040077143 Cratering Rates on the Galilean Satellites Author(s): Zahnle, Kevin; Dones, Luke Abstract: In the inner solar system, impact craters are made mostly by asteroids and long-period comets. The Jupiter family of comets, whose comets are in relatively short-period,low-inclination orbits dominated dynamically by ... NASA Center: Ames Research Center Publication Year: 1998 Added to NTRS: 2005-11-24 Document ID: 20040075732 Carbon Dioxide Cycling and the Climate of Ancient Earth Author(s): Zahnle, Kevin; Sleep, Norman H. Abstract: The continental cycle of silicate weathering and metamorphism dynamically buffers atmospheric CO2 and climate. Feedback is provided by the strong temperature dependence of silicate weathering. Here we argue that hydrothermal ... NASA Center: Ames Research Center Publication Year: 2001 Added to NTRS: 2005-08-25 Document ID: 20020002146 Cratering Rates on Synchronously Rotating Satellites Author(s): Zahnle, Kevin; Schenk, Paul Abstract: Impact cratering of synchronously rotating satellites is expected to occur faster on the leading hemisphere than on the trailing hemisphere because the orbital velocity of the satellite around the planet is generally large ... NASA Center: Ames Research Center Publication Year: 2002 Added to NTRS: 2005-08-25 Document ID: 20040171746 The collision of Jupiter and Comet Shoemaker-Levy 9 Author(s): Zahnle, Kevin; Mac Low, Mordecai-Mark Abstract: A simple description of the disruption and deceleration of 100-m- to 5-km-diameter comets striking Jupiter is combined with numerical simulations of the subsequent explosions to predict the fate of Comet Shoemaker-Levy 9. ... NASA Center: Ames Research Center, Goddard Space Flight Center Publication Year: 1994 Added to NTRS: 2004-11-03 Accession Number: 95A63429; Document ID: 19950031830 Cratering Rates in the Outer Solar System Author(s): Zahnle, Kevin Abstract: We have constructed a self-consistent study of cratering rates in the outer solar system. Two papers were written, one on cratering asymmetries on synchronously rotating satellites and the other on the cratering rates ... NASA Center: Ames Research Center Publication Year: 2003 Added to NTRS: 2004-11-03 Document ID: 20030112096; Report Number: Rept-1 Models of Fallback Author(s): Zahnle, Kevin Abstract: The impact of a typical Shoemaker-Levy 9 fragment produced three light peaks as seen from Earth. The first peak is related to the entry of the fragment into the jovian atmosphere. The second peak occurs when the exploding ... NASA Center: Ames Research Center Publication Year: 1995 Added to NTRS: 2004-11-03 Document ID: 20020027488 Impact origin of Titan's atmosphere Author(s): Zahnle, Kevin; Dones, L. Abstract: The reason why Titan has a thick atmosphere while its Jovian clones Ganymede and Callisto have nothing is addressed. It is argued that this contrast is a predictable consequence of impact erosion, i.e., the escape of ... NASA Center: Ames Research Center Publication Year: 1992 Added to NTRS: 2004-11-03 Accession Number: 92N32351; Document ID: 19920023107 1 2 3 Next  + Back to Top + Sponsored by the NASA Scientific and Technical    Information Program + 2004 Vision for Space Exploration + Freedom of Information Act + NASA Web Privacy Policy and Important Notices + NASA Disclaimers, Copyright Notice,    and Terms and Conditions of Use NASA Official: Calvin Mackey Page Curator: NASA Center for AeroSpace Information (help@sti.nasa.gov) Last Updated: July 5, 2007