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E. G. Reffet, G. M. Boubin (Universite Paris 7 D.Diderot), J. Lunine, J. Radebaugh (University of Arizona), R. M. Lopes (Jet Propulsion Laboratory), Cassini Radar Team
We present an interpretation of a portion of the Synthetic Aperture Radar (SAR) data from the first Cassini flyby of Titan (October 16th 2004, Ta) during which a part of the northern hemisphere was imaged with a varying resolution of 0.4-1 km/pixel. This image swath reveals a complex area with many features not yet understood [1,2]. We discuss the existence of a volcanic field [2,3,4] and its consistency with observations and models.
Cryovolcanism on Titan. Titan is likely composed of an icy crust above a liquid layer of ammonia-water. Like silicates, the melt is less dense than the solid, so it is conceivable for cryovolcanism to occur. Consideration of gravity- and temperature-scaling of viscosities [5] shows that ammonia-water lava on Titan behaves similarly to basaltic lava on Earth, in terms of viscosity and flow morphology. From the same lava composition, different surface structures can occur [6]. Differences in flow, cooling, and crystallization result either in smooth and lobate surfaces that are radar-dark or in surfaces that are rough and clinkery and hence radar-bright [7].
Area of study. The area located at 75-90 degrees W and 45-55 degrees N is a tangle of bright and dark lobate regions, some bright channel-like features, and a few small, dark, circular features. We propose that different surface structures of cryovolcanic flows can explain these variations. We present a geomorphologic map of this region, with boundaries delineated mainly by differences in brightness, and with some possible volcanic vents, cones, and craters outlined.
Acknowledgements. The authors acknowledge the support of LPL and thank the Cassini RADAR team. References. [1] Paganelli e.a. LPSC 2005. [2] Lopes e.a. LPSC 2005. [3] Stofan e.a. LPSC 2005. [4] Elachi e.a. Science 2005. [5] Kargel e.a. Icarus, 1990. [6] Peterson and Tilling. JVGR, 1980. [7] Spaceborne Radar Observations. NASA, JPL.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.