Titan atmosphere

Exobiology a b s t r a c t Since Titan entered Northern spring in August 2009, the North Pole has been illuminated allowing obser-vations at optical wavelengths. On June 5, 2010 the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft observed the Northern Pole area with a pixel size from 3 to 7 km. Since, as we demonstrate, little of the solar flux at 5 lm is scattered by the atmosphere, these observations were obtained at relatively large incidence angles and allowed us to build a mosaic covering an area of more than 500,000 km2 that overlaps and complements observations made by the Synthetic Aperture Radar (SAR) in 2007. We find that there is an excellent correlation between the shape of the radar dark area, known as Ligeia Mare and the VIMS 5-lm dark unit. Matching most of the radar shoreline, the 2010 VIMS observations suggest that the 125,000-km2 surface area of Ligeia Mare measured by RADAR in 2007 ha