The Cassini spacecraft reveals details on the surface of small, irregularly shaped Helene in this close-up view, obtained during the spacecraft's closest encounter with this moon during its four-year primary mission.
Helene (32 kilometers, or 20 miles across) is a Trojan moon, sharing Dione's orbit but staying 60 degrees or 400,000 kilometers (250,000 miles) ahead of the much larger moon.
The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 20, 2007. The view was acquired at a distance of approximately 39,000 kilometers (24,000 miles) from Helene and at a Sun-Helene-spacecraft, or phase, angle of 61 degrees. Image scale is 231 meters (758 feet) 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