HR: 16:20h
AN: P44A-01    [Abstracts]
TI: Early History of Titan
AU: Castillo-Rogez, J C
EM: Julie.C.Castillo@jpl.nasa.gov
AF: Jet Propulsion Laboratory - California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: * Matson, D L
EM: Dennis.L.Matson@jpl.nasa.gov
AF: Jet Propulsion Laboratory - California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Johnson, T V
EM: Torrence.V.Johnson@jpl.nasa.gov
AF: Jet Propulsion Laboratory - California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Atreya, S
EM: atreya@umich.edu
AF: Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, United States
AU: Lunine, J I
EM: jlunine@lpl.arizona.edu
AF: Jet Propulsion Laboratory - California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States
AU: Lunine, J I
EM: jlunine@lpl.arizona.edu
AF: Lunar and Planetary Lab, 1629 E. University Blvd., Tucson, AZ 85721, United States
AB: We revisit models for the early history of Titan. Our models start a few My after the production of calcium- aluminum inclusions (CAIs), consistent with the dates required by our thermophysical-dynamical modeling of Saturn's medium-sized satellites. Depending on the time of formation with respect to CAIs, the accretion time scale, and the available accretional energy, models of Titan's interior after accretion are partially to fully differentiated. At one extreme of the models, Titan accretes incorporating a minimal amount of heat. This results in a relatively cold core that, over the long term, heats up and overturns, consistent with previous models of Titan. At the other extreme, accretional heat and heat fom the decay of short-lived radiogenic isotopes results in quick and complete differentiation. In this model there is no core overturn, and conditions soon develop for silicate serpentinization, and hydrothermal activity starts. We identify the periods during which conditions are suitable for hydrothermal geochemistry leading to the production of molecular nitrogen from ammonia decomposition and methane from the Fischer-Tropsch reaction. Key questions include the availability of suitable metal catalysts and/or clay minerals, storage of the reactants and products in the interior of Titan, and mechanisms by which they are released to the atmosphere. Acknowledgements: This work was carried out at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA.
DE: 6024 Interiors (8147)
DE: 6280 Saturnian satellites
DE: 8147 Planetary interiors (5430, 5724, 6024)
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly