On June 16, NASA's Cassini spacecraft will travel very close to Saturn's moon Dione. It will reach within 321 miles of the moon's surface. On August 17, it will fly past Dione once again, plunging within 295 miles of the surface.

Cassini's cameras and spectrometers will be observing terrain that consists of 'Eurotas Chasmata', which is a region that was first observed 35 years ago by NASA's Voyager mission. Scientists expected that observed streaks were bright material ejected onto the surface by geologic activity, like ice volcanoes. The spacecraft will also try to detect and find out the composition of any fine particles, emitted from Dione, which could show low-level geologic activity.

It is expected by mission controllers that images will be returned to earth within a few days of the encounter.

It will be the fourth targeted encounter with Dione of Cassini's long mission. A propulsion maneuver will be required to accurately guide the spacecraft in the direction of a desired path above a moon for targeted encounters. Earlier, Cassini's closest-ever flyby of Dione occurred in December 2011, at a distance of 60 miles (100 kilometers).

The spacecraft will leave Saturn's equatorial plane in late 2015. Moon flybys take place most frequently in Saturn's equatorial plane.

The Cassini-Huygens mission is a joint project of three space agencies i. e. NASA, ESA (European Space Agency) and the Italian Space Agency. JPL is a division of the California Institute of Technology in Pasadena, which manages the mission for NASA's Science Mission Directorate in Washington.