The Sand Seas of Titan: Cassini RADAR Observations of Longitudinal Dunes
Lorenz, R. D.; Stiles, B.; Kelleher, K.; Callahan, P.; Gim, Y.; Encrenaz, P.; Roth, L.; Picardi, G.; Paganelli, F.; Stofan, E.; Elachi, C.; Ori, G. G.; West, R.; Mitchell, K.; Kirk, R.; Radebaugh, J.; Wall, S.; Janssen, M.; Lopes, R.; Lunine, J.; Soderblom, L.; Wood, C.; Wye, L.; Zebker, H.; Anderson, Y.; Ostro, S.; Allison, M.; Boehmer, R.; Flamini, E.; Francescetti, G.; Hamilton, G.; Hensley, S.; Johnson, W.; Muhleman, D.; Posa, F.; Seu, R.; Shaffer, S.; Vetrella, S.; Reffet, E.; Boubin, G.
United States, France, Italy
Abstract
The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show ~100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of ~0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.