July 5, 2006
Dramatic edge-on Cassini views of Saturn's E ring, like these side-by-side images, reveal for the first time a double-banded structure. The structure is similar to that of Jupiter's gossamer ring and to the bands of dust found within the solar system's asteroid belt. Scientists believe that the E ring particles have their origins in the geysers erupting from the south polar of Enceladus.
The double-banded appearance exists because there are fewer particles close to the ring plane than 500 to 1,000 kilometers (300 to 600 miles) above and below. This circumstance can arise if the particles making up the ring encircle Saturn on inclined orbits with a very restricted range of inclinations.
This special condition might exist for two reasons. One possibility is that the particles being jetted out of Enceladus and injected into Saturn orbit may begin their journey around Saturn with a certain velocity, and consequently a restricted range of inclinations, with respect to the ring plane. Another is that the particles may begin with a large range of inclinations, but those orbiting very close to the ring plane get gravitationally scattered and removed from that region by the passage of Enceladus.
Scientists will continue to observe the E ring from various angles to confirm and understand the structure.
Most of the bright specks in the images are background stars, although a few are cosmic ray hits on the camera's detector.
The two images were taken five hours apart on Dec. 1, 2005, when Cassini was approximately 1.9 million kilometers (1.2 million miles) from Saturn. The image scale on the sky at the distance of Saturn is about 220 kilometers (137 miles) per pixel.
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, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.
Credit:NASA/JPL/Space Science Institute