An Apparent Increase in Flux from a Surface Feature on Titan: Implications for Surface and Atmosphere

We observed an apparent increase in flux from a region of Titan's surface between the time of the initial Titan flyby in July 2004 (T0) and the next flybys, 8 and 9 months later (T4 and T5). The approximate location of the region is lat=-25 lon=80. At the T0 flyby this was the brightest point on Titan at 2 microns as measured by Cassini's Visual and Infrared Mapping Spectrometer-VIMS. It was included as a photometric control point. After six flybys this point remains the brightest region on Titan and its flux appears to have increased. The increase was also observed at 1.28, 1.57, and 4.97 microns, other wavelengths where VIMS can see Titan's surface. The magnitude of this increase was greatest at 2.0178 microns, where the intensity increased 11-15% depending on method of analysis used. This preliminary result may still be only apparent, arising from photometric or calibration effects; hence we require further analyses to verify the changes. Possible causes include atmospheric processes such as ground fogs or orographic clouds and even possible active volcanism in the 9-month period. These and other possibilities will be investigated extensively as new data become available during the Cassini orbital tour. This work done at JPL under contract with NASA