[hal-01088824] Looking for Thermal Anomalies on Titan's Surface

A radiometric brightness map of Titan at 2-cm wavelength has been constructed from seven years worth of observations by the Cassini RADAR. To the extent that Titan's surface temperature distribution is known from a combination of Huygens probe, far infrared, and radio occultation measurements, this map can be used to construct a map of emissivity. This can in turn be compared with the radar reflectivity map, which now covers half of Titan at SAR resolution. Emissivity and reflectivity are related through Kirchhoff's law of thermal radiation. One can use this comparison to test the assumption that we indeed know Titan's surface physical temperature everywhere, noting that a possible thermal anomaly due to active cryovolcanism may be present that, if strong enough, would appear as an emissivity that is too high for the measured reflectivity. Thermal anomalies as small as a few degrees averaged over a radiometer footprint could be observed. The possible existence of such anomalies and their relation to surface features will be discussed. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.



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