Interplanetary profile: Dione

"Orbiting Saturn within the tenuous E-ring, Dione possesses fine streaks that crosscut its surface. Parallel grooves splash across the terrain, which are interrupted by larger, asymmetrical bright fractures. Scientists believe the cracks and fractures were caused by tectonic activity."

You can follow this NASA link to find out more about Dione and the rest of the Cassini mission.