Surface Reflectance Change on Titan: Implications for Atmospheric and Volcanic Activity

Regional changes in the near-infrared reflectance of a 2800 km 2 area on Titan occurred between July 2004 and October of 2005 Cassini s Visual and Infrared Imaging Spectrometer observed a flux increase by a factor of two between July 2004 and March-April 2005 then a decrease through October 2005 The character is inconsistent with tropospheric clouds of the type observed at Titan s South pole and high mid-latitudes Application of a comprehensive radiative transfer model finds that it is unlikely to be caused by a ground fog and most likely occurred at Titan s surface This is the first direct evidence of short-term surface change on Titan Inspection of the spectral differences between the spot and its surrounding terrain rules out changes in the distribution of the ices of H 2 O CO 2 and CH 4 as the cause Interpretations include changing surface deposits due to abrupt tectonic or volcanic activity This is the first evidence for currently active tectonic processes such as volcanism on Titan This work done at JPL CALTECH under contract with NASA