Cassini to Make Last Close Flyby of Dione

[bystander]

Cassini to Make Last Close Flyby of Dione
NASA | JPL-Caltech | Cassini Solstice Mission | 2015 Aug 13

[img3="A view of Saturn's moon Dione captured by NASA's Cassini spacecraft during a close flyby on June 16, 2015. The diagonal line near upper left is the rings of Saturn, in the distance. Image Credit: NASA/JPL-Caltech/Space Science Institute"]http://www.jpl.nasa.gov/images/cassini/ ... 813-16.jpg[/img3][hr][/hr]

NASA's Cassini spacecraft will zip past Saturn's moon Dione on Monday, Aug. 17 -- the final close flyby of this icy satellite during the spacecraft's long mission.

Cassini's closest approach, within 295 miles (474 kilometers) of Dione's surface, will occur at 11:33 a.m. PDT (2:33 p.m. EDT). Mission controllers expect fresh images to begin arriving on Earth within a couple of days following the encounter.

Cassini scientists have a bevy of investigations planned for Dione. Gravity-science data from the flyby will improve scientists' knowledge of the moon's internal structure and allow comparisons to Saturn's other moons. Cassini has performed this sort of gravity science investigation with only a handful of Saturn's 62 known moons.

During the flyby, Cassini's cameras and spectrometers will get a high-resolution peek at Dione's north pole at a resolution of only a few feet (or meters). In addition, Cassini's Composite Infrared Spectrometer instrument will map areas on the icy moon that have unusual thermal anomalies -- those regions are especially good at trapping heat. Meanwhile, the mission's Cosmic Dust Analyzer continues its search for dust particles emitted from Dione. ...

[bystander]

Chasms on Dione
NASA | JPL-Caltech | Cassini Solstice Mission | 2015 Aug 17

[img3="Credit: NASA/JPL-Caltech/Space Science Institute"]http://photojournal.jpl.nasa.gov/jpeg/PIA18327.jpg[/img3][hr][/hr]

While not bursting with activity like its sister satellite Enceladus, the surface of Dione is definitely not boring. Some parts of the surface are covered by linear features, called chasmata, which provide dramatic contrast to the round impact craters that typically cover moons.

The bright network of fractures on Dione (698 miles or 1,123 kilometers across) was seen originally at poor resolution in Voyager images and was labeled as "wispy terrain." The nature of this terrain was unclear until Cassini showed that they weren't surface deposits of frost, as some had suspected, but rather a pattern of bright icy cliffs among myriad fractures. One possibility is that this stress pattern may be related to Dione's orbital evolution and the effect of tidal stresses over time.

This view looks toward the trailing hemisphere of Dione. North on Dione is up. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on April 11, 2015.

The view was acquired at a distance of approximately 68,000 miles (110,000 kilometers) from Dione. Image scale is 2,200 feet (660 meters) per pixel.

[bystander]

Cassini's Final Breathtaking Close Views of Dione
NASA | JPL-Caltech | Cassini Solstice Mission | CICLOPS | 2015 Aug 20

A pockmarked, icy landscape looms beneath NASA's Cassini spacecraft in new images of Saturn's moon Dione taken during the mission's last close approach to the small, icy world. Two of the new images show the surface of Dione at the best resolution ever.

Cassini passed 295 miles (474 kilometers) above Dione's surface at 11:33 a.m. PDT (2:33 p.m. EDT) on Aug. 17. This was the fifth close encounter with Dione during Cassini's long tour at Saturn. The mission's closest-ever flyby of Dione was in Dec. 2011, at a distance of 60 miles (100 kilometers). ...

The main scientific focus of this flyby was gravity science, not imaging. This made capturing the images tricky, as Cassini's camera was not controlling where the spacecraft pointed. ...

[img3="This view from NASA's Cassini spacecraft looks toward Saturn's icy moon Dione, with giant Saturn and its rings in the background, just prior to the mission's final close approach to the moon on August 17, 2015.
Image Credits: NASA/JPL-Caltech/Space Science Institute"]http://www.nasa.gov/sites/default/files ... 0_main.jpg[/img3]

[img3="Dione hangs in front of Saturn and its icy rings in this view, captured during Cassini's final close flyby of the icy moon. "]http://s3.amazonaws.com/ciclops_ir_2015 ... 9564_1.jpg[/img3]

---

The full set of images released today is available at the JPL Photojournal and CICLOPS.