Cassini to make last close flyby of Saturn moon Dione

August 14, 2015 by Preston Dyches, Jet Propulsion Laboratory
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. Credit: NASA/JPL-Caltech/Space Science Institute

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 will improve scientists' knowledge of the '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.

This flyby will be the fifth targeted encounter with Dione of Cassini's tour at Saturn. Targeted encounters require maneuvers to precisely steer the spacecraft toward a desired path above a moon. The spacecraft executed a 12-second burn using its thrusters on Aug. 9, which fine-tuned the trajectory to enable the upcoming encounter.

Cassini's closest-ever flyby of Dione was in Dec. 2011, at a distance of 60 miles (100 kilometers). Those previous close Cassini flybys yielded high-resolution views of the bright, wispy terrain on Dione first seen during the Voyager mission. Cassini's sharp views revealed the bright features to be a system of braided canyons with bright walls. Scientists also have been eager to find out if Dione has geologic activity, like Saturn's geyser-spouting moon Enceladus, but at a much lower level.

"Dione has been an enigma, giving hints of active geologic processes, including a transient atmosphere and evidence of ice volcanoes. But we've never found the smoking gun. The fifth flyby of Dione will be our last chance," said Bonnie Buratti, a Cassini science team member at NASA's Jet Propulsion Laboratory in Pasadena, California.

Cassini has been orbiting Saturn since 2004. After a series of close moon flybys in late 2015, the spacecraft will depart Saturn's equatorial plane—where moon flybys occur most frequently—to begin a year-long setup of the mission's daring final year. For its grand finale, Cassini will repeatedly dive through the space between Saturn and its rings.

"This will be our last chance to see Dione up close for many years to come," said Scott Edgington, Cassini mission deputy project scientist at JPL. "Cassini has provided insights into this icy moon's mysteries, along with a rich data set and a host of new questions for scientists to ponder."

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Jonseer
not rated yet Aug 14, 2015
What a waste of an ending.

The craft should be steered towards Titan in order to give it the slowest possible decent allowing for pictures to be taken of deep inside Titan's atmosphere.

That they chose otherwise to avoid possibly contaminating Titan with evil Earth microbes is proof environmentalism has run a muck in the space program. It needs to be rooted out, before any more grand explorations missions are designed and launched.

The chances of any Earth microbe surviving so long in deep space let alone being able to survive and multiply on the surface of Titan regardless of resources due to the temps. is in real terms non-existent. We've never even found a shred of proof that any Earth organism can survive in those conditions.

It's ironic that we will lose such a golden opportunity, because the science establishment opts to believe in make believe rather than common sense.

JustAnotherGuy
5 / 5 (1) Aug 17, 2015
Jonseer... you will enjoy this... I did it! ...some time ago...
Cassini's team have envisioned about Titan's images too, and designed the Huygens probe:
http://phys.org/n...tan.html

Fasten your parachute and boost your speakers' volume for this one:
http://apod.nasa....121.html

Don't worry on environmentalists and microbes, looks like nobody does:
http://phys.org/n...lds.html
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The chosen Cassini's end seems wise. The 'dirty work' for the last.
Now, if I were to chose, I would send it to Mimas, aka the "Death Star".
https://en.wikipe...s_(moon)

There's an...hum... urban myth... which claims that a single small-sized ship can take down one of these alone... (:p)
http://img4.wikia...game.jpg

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