These raw, unprocessed images of Saturn's moon Dione were taken on Dec. 12, 2011, by NASA's Cassini spacecraft. Although Cassini obtained more detailed images on previous flybys of Dione, this was the spacecraft's closest pass of the moon's surface. Cassini passed within approximately 62 miles (99 kilometers) of Dione. Cassini's previous closest passes of the moon were Oct. 11, 2005 and April 7, 2010. Those flybys each were about 300 miles (500 kilometers) from Dione.
This Dione encounter was intended primarily for Cassini's composite infrared spectrometer and radio science subsystem. However, the imaging team did capture views of the distinctive, wispy fractures on Dione's trailing hemisphere and a ridge called Janiculum Dorsa on the moon's leading hemisphere. The best resolved images from this flyby have scales ranging from about 1,100 feet (350 meters) to about 1,600 feet (500 meters) per pixel. Janiculum Dorsa will be imaged at higher resolution in May 2012.
Dione is joined by other moons in some of these views. Mimas appears just beyond the dark side of Dione in one view and just beyond the edge of the visible disk of Dione in another. Epimetheus and the planet's rings appear in two images, once with Prometheus and once with Pandora. Potato-shaped Prometheus appears at the bottom center of the image in which it appears. Pandora, which is similar in size to Prometheus, appears above the rings and Epimetheus in its image.