37th DPS Meeting, 4-9 September 2005
Session 46 Titan's Surface and Magnetic Environment
Poster, Wednesday, September 7, 2005, 6:00-7:15pm, Music Recital Room

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[46.14] CASSINI/VIMS Observations of the Huygens Probe Landing Site

S. Rodriguez, S. Le Mouelic, C. Sotin, H. Clenet (Laboratoire de Planetologie et de Geodynamique de Nantes, France), B. Buratti (JPL), R. N. Clark (USGS, Denver), R. H. Brown (U. Arizona), K .H. Baines (JPL), T. B. McCord (HIGP/SOEST, Hawaii), R. M. Nelson (JPL), VIMS Team

The VIMS (Visual and Infrared Mapping Spectrometer) instrument onboard Cassini acquires hyperspectral images with two separate detectors, one in the visible ranging from 0.35 to 1.05 micron, and one in the infrared from 0.88 to 5.1 microns, with a total of 352 spectral channels. VIMS has proved to be able to see through the thick Titan haze and successfully take medium to high resolution images of Titan surface in eight infrared spectral windows, where atmospheric methane absorptions are the weakest. On 26 October (TA flyby) and 13 December 2004 (TB flyby), the Cassini-Huygens mission flew over Titan at an altitude lower than 1200 km at closest approach and the VIMS instrument imaged the site where the Huygens probe successfully landed on 14th January 2005, with a spatial resolution ranging from 16 to 14.4 kilometers per pixel. No major change between TA and TB is observed, despite the 48 days time span. We report here the analysis of these images using ratios between bands centred in the methane windows. These ratios are corrected from atmospheric scattering effects by the mean of both an empirical method and a first order theoretical model. Band ratios allow us to investigate the compositional heterogeneity of the region of the surface where the Huygens probe landed, giving new clues on the local nature of Titan surface in terms of morphology and composition. While the surface is uniformly composed of bright and dark areas on raw images (the only particular structure revealed is a circular feature that may be an impact crater), corrected band ratios reveal some features totally decorrelated from albedo, witnessing possible surface heterogeneities. Some of these features could be related with local enrichment in water ice content or grain size variation in hydrocarbons. Others variations are still under interpretation in terms of surface composition. The VIMS data obtained at the Huygens landing site are also compared with the data acquired by the instruments onboard Huygens, which provides ground truth for our remote sensing observations.

The author(s) of this abstract have provided an email address for comments about the abstract: sebastien.rodriguez@univ-nantes.fr

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