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G. M. Boubin, E. G. Reffet (Universite Paris 7 D.Diderot), J. Lunine, J. Radebaugh (University of Arizona), R. M. Lopes (Jet Propulsion Laboratory), Cassini Radar Team
During the T3 Cassini spacecraft flyby on 15 February 2005, an image swath of the 5 degrees N, 125 degrees W to 5 degrees N, 10 degrees W region of Titan was obtained by the RADAR mapper operating in synthetic aperture mode (SAR)[1]. In many parts of the swath, big fields of large, longitudinal black stripes known as ``cat scratches" appear. They range in size from 1-10 km wide and from 10-100 km long, and are roughly E-W in orientation, with some variations. These features have the same RADAR properties as dunes on Earth, in particular in contrast, form, length and width. In the west part of the swath, the cat scratches look like snow dunes in Antarctica called megadunes [2] which need a strong, constant wind and a specific surface slope to be formed. In the east part they are similar to longitudinal sand dunes [3].
We seek to understand if Titan's surface is a good candidate for dune formation. In order to make dunes, there must be supply of material and wind. Materials could be fine organic or impact ejecta particles. Our study consists of making precise descriptions, measurements, and maps of the cat scratch fields and comparing these with models of Titan's winds [4], erosion [5] and surface properties [6] in terms of dune formation [3]. The presence of such scratches, and other features like possible wind streaks, would constrain the wind profile, topography and relief, origin and nature of transported particles, and weather on Titan.
Acknowledgements: The authors acknowledge the support of LPL and thank the Cassini RADAR team.
References: [1] Spaceborne Radar Observations NASA, JPL; [2] Frezzotti e.a. Snow megadunes in Antartica. 2002; [3] Greeley and Iversen Wind as a geological process; [4] Tokano. Icarus. 2002; [5] Lorenz and Lunine. Icarus. 1995; [6] Lorenz e.a. Prediction of aeolian features on planets. 1995.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.