Today, it will zip past the moon and gather data as it continues on its mission.
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Since arriving in Saturn orbit in 2004, Cassini has only been able to gain such a close view of a handful of Saturn’s 62 known moons, so every flyby of the Saturnian satellites it can make close encounters with is of extreme scientific importance. As well as, Cassini’s Composite Infrared Spectrometer instrument will map areas on the icy moon which have uncommon thermal anomalies – these areas are particularly good at trapping warmth. These earlier shut Cassini flybys yielded high-resolution views of the brilliant, wispy terrain on Dione first seen through the Voyager mission.
This image from NASA’s Cassini spacecraft shows a part of Dione’s surface that is covered by linear, curving features, called chasmata. Previous flyby images illustrated Dione’s canyons and bright features.
Scientists have been curious about Dione’s geological activity since Saturn’s other moon, Enceladus has geysers.
Bonnie Buratti is a Cassini science team member at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Cassini’s closest-ever flyby of Dione was in December. 2011, at a distance of 60 miles (100 kilometers). The fifth flyby of Dione will be our last chance.
The study now examines that “Dione has been an enigma, giving hints of active geologic processes, including a transient atmosphere and evidence of ice volcanoes”.
The findings that Cassini sends back may reveal a bit more about Saturn and one of its many moons. But, they never discovered the smoking gun as the spacecraft’s fifth flyby will be their last chance. The final act of the mission will take a year to setup before the spacecraft makes the dive through Saturn’s expansive rings.
National Geographic points out that backyard skywatchers can get a glimpse of Saturn’s Cassini division (the largest dark gap between Saturn’s rings) this week.
Scott Edgington is Cassini mission deputy project scientist at JPL.
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In the 11 years the Cassini probe has explored the Saturn system, it’s visited seemingly sleepy Dione four times. “Cassini has offered insights into this icy moon’s mysteries, together with a wealthy knowledge set and a number of latest questions for scientists to ponder”.
