This image shows the first flash of sunlight reflected off a lake on Saturn's moon Titan. The glint off a mirror-like surface is known as a specular reflection. The Visual and Infrared Mapping Spectrometer (VIMS) on NASA's Cassini spacecraft detected this glint on 8 July 2009. It confirmed the presence of liquid in the moon's northern hemisphere, where lakes are more numerous and larger than those in the southern hemisphere. Scientists using VIMS had confirmed the presence of liquid in Ontario Lacus, the largest lake in the southern hemisphere, in 2008.
The northern hemisphere was shrouded in darkness for nearly 15 years, but the Sun began to illuminate the area again as it approached its spring equinox in August 2009. VIMS was able to detect the glint as the viewing geometry changed. Titan's hazy atmosphere also scatters and absorbs many wavelengths of light, including most of the visible light spectrum. However, the VIMS instrument enabled scientists to look for the glint in infrared wavelengths that were able to penetrate through the moon’s atmosphere. This image was created using wavelengths of light in the five micron range.
By comparing the new image to radar and near-infrared light images acquired from 2006 to 2008, Cassini scientists were able to correlate the reflection to the southern shoreline of a Titan lake called Kraken Mare. The sprawling Kraken Mare covers about 400,000 square kilometres. The reflection appeared to come from a part of the lake around 71 degrees north latitude and 337 degrees west latitude.
It was taken on Cassini's 59th flyby of Titan on 8 July 2009, at a distance of about 200,000 kilometres. The image resolution was about 100 kilometres per pixel. Image processing was done at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in Berlin and the University of Arizona in Tucson.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson.
Credit: NASA/JPL/University of Arizona/DLR.