December 1, 2011
This image shows grooves in the southern part of Saturn's moon Enceladus. The image was created using synthetic-aperture radar (SAR) data acquired by NASA's Cassini spacecraft on Nov. 6, 2011. The radar image is overlaid in light blue over an earlier visible-light image (Map of Enceladus - December 2006). The SAR swath shown is 15.5 miles (25 kilometers) wide and provides a close-up view of the grooved, water-ice bedrock present in this region. This region is a few hundred miles north of the vents from which plumes of water vapor and icy material have been previously detected (Enceladus' Warm Baghdad Sulcus). The image is centered at 65 south latitude and 293 west longitude.
Both visible-light and SAR images show the shape of features and give information about the features' composition. But whereas visible-light images (like we normally see in photographs) tell us about chemical composition, SAR images tell us about electric properties. Electric properties help us distinguish one material from another. Here, shadowing in this SAR imagery also emphasizes smaller undulations in the surface interspersed in the terrain surrounding the large groove. These appear to be relatively young features that may have formed from extension, or pulling apart, of Enceladus' crust due to effects of Saturn's gravity. Since the radar illumination is from the upper right (perpendicular to the swath), the upper slopes of grooves are dark and the lower (left) slopes are bright. Analysis of the slopes and their shading reveal that the central, prominent groove is about 2,100 feet (650 meters) deep and 1.2 miles (2 kilometers) wide, with slopes of about 33 degrees.
This large groove is similar to Enceladus' famous "tiger stripes." These large fractures are the source of the jets of icy particles and water vapor that erupt from the moon's southern polar region. They are much warmer than the rest of the moon's surface, indicating a subsurface source of heat.
These images of Enceladus show some similarity to those obtained of Saturn's largest moon Titan. Titan's large feature Xanadu (Xanadu: Rivers Flowed onto a Sunless Sea) is also very bright, as are areas surrounding the crater Sinlap (Titan Crater in Three Views). Whether the bright areas seen here are due to the same, or very different, processes will be a subject of discussion as scientists continue to learn more about the moons of Saturn.
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. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.
Credit: NASA/JPL-Caltech/Space Science Institute