Titan's inventory of organic surface materials

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Read Full Article (file size: 192762 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L02206, doi:10.1029/2007GL032118, 2008 Titan's inventory of organic surface materials Ralph D. Lorenz Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA Karl L. Mitchell Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Randolph L. Kirk U.S. Geological Survey, Flagstaff, Arizona, USA Alexander G. Hayes Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA Oded Aharonson Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA Howard A. Zebker Departments of Geophysics and Electrical Engineering, Stanford University, Stanford, California, USA Phillipe Paillou UMR 5804, Laboratorie d'Astrophysique de Bordeaux, Observatorie Aquitain des Sciences de l'Univers, Floirac, France Jani Radebaugh Department of Geological Sciences, Brigham Young University, Provo, Utah, USA Jonathan I. Lunine Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA Michael A. Janssen Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Stephen D. Wall Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Rosaly M. Lopes Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Bryan Stiles Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Steve Ostro Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Giuseppe Mitri Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA Ellen R. Stofan Proxemy Research, Rectortown, Virginia, USA Abstract Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas reserves on Earth. Dark dunes cover some 20% of Titan's surface, and comprise a volume of material several hundred times larger than Earth's coal reserves. Overall, however, the identified surface inventories (>3 × 10⁴ km³ of liquid, and >2 × 10⁵ km³ of dune sands) are small compared with estimated photochemical production on Titan over the age of the solar system. The sand volume is too large to be accounted for simply by erosion in observed river channels or ejecta from observed impact craters. The lakes are adequate in extent to buffer atmospheric methane against photolysis in the short term, but do not contain enough methane to sustain the atmosphere over geologic time. Unless frequent resupply from the interior buffers this greenhouse gas at exactly the right rate, dramatic climate change on Titan is likely in its past, present and future. Received 2 October 2007; accepted 26 November 2007; published 29 January 2008. Keywords: Titan; surface; organics. Index Terms: 6281 Planetary Sciences: Solar System Objects: Titan; 5470 Planetary Sciences: Solid Surface Planets: Surface materials and properties; 5464 Planetary Sciences: Solid Surface Planets: Remote sensing; 5405 Planetary Sciences: Solid Surface Planets: Atmospheres (0343, 1060). Read Full Article (file size: 192762 bytes) Cited by Citation: Lorenz, R. D., et al. (2008), Titan's inventory of organic surface materials, Geophys. Res. Lett., 35, L02206, doi:10.1029/2007GL032118. Copyright 2008 by the American Geophysical Union.

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