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1 Applied Physics Lab 2 JPL - Jet Propulsion Laboratory 3 US Geological Survey 4 Department of Geological and Planetary Sciences 5 Department of Electrical Engineering Stanford 6 L3AB - Laboratoire d-astrodynamique, d-astrophysique et d-aéronomie de bordeaux 7 OASU - Observatoire aquitain des sciences de l-univers 8 Department of Geological Sciences BYU 9 Lunar and Planetary Lab 10 Proxemy Research Inc

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.

Keywords : Planetary Sciences: Solar System Objects: Titan Planetary Sciences: Solid Surface Planets: Surface materials and properties Planetary Sciences: Solid Surface Planets: Remote sensing Planetary Sciences: Solid Surface Planets: Atmospheres 0343 1060

Author: Ralph D. Lorenz - Karl L. Mitchell - Randolph L. Kirk - Alexander G. Hayes - Oded Aharonson - Howard A. Zebker - Philippe Paillou

Source: https://hal.archives-ouvertes.fr/


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