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Titan's inventory of organic surface materials
Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
U.S. Geological Survey, Flagstaff, Arizona, USA
Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Departments of Geophysics and Electrical Engineering, Stanford University, Stanford, California, USA
UMR 5804, Laboratorie d'Astrophysique de Bordeaux, Observatorie Aquitain des Sciences de l'Univers, Floirac, France
Department of Geological Sciences, Brigham Young University, Provo, Utah, USA
Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Proxemy Research, Rectortown, Virginia, USA
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.
Citation: (2008), Titan's inventory of organic surface materials, Geophys. Res. Lett., 35, L02206, doi:10.1029/2007GL032118.
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