A Different Look At Titans Dunes
Résumé
In its six Titan flybys (T16: July 2006) the Cassini's Titan Radar Mapper has imaged yet again more evidence of dark linear streaks and/or dunes. The latitude, between 14-25 N, and orientation of these features is comparable to the one seen in the T3 (February 2005) Titan flyby. The implications of these new observation stand on the particular geometry in which the dunes have been imaged in the radar swath and consequently on the effect that this has on their characterization. Previous flyby geometries had look direction perpendicular to the general azimuth of the dunes, thus allowing identification of dunes with generally observed E-W orientation (see also Radebaugh et al., this conference) and --because of the favorable geometry -- to identify their topographic expression. T16 has shown that the same dark linear streaks and/or dunes trend can be imaged with look direction quasi-parallel to them, very similar to the + 25 E-W azimuth in T3. This has the implication that these features might be superposed streaks with none or minimal topography, and that they are visible because of differential erosion between the radar bright rougher substrate and the radar dark of fine particle smooth surface deposits. This paper will asses the imaging geometry at which these dark linear streaks and/or dunes are seen in T16 and T3 flybys, and what the data are telling us in terms of their physical and morphological properties.