Cryovolcanism on Dione?

3488 · Apr 24, 2007

Icy Volcanoes Likely Shape Saturn's Smooth Moon By David Powell Special to SPACE.com posted: 24 April 2007 06:01 am EDT Saturn’s icy moon Dione may have much in common with its active sibling Enceladus, new research using Cassini spacecraft data has revealed. Paul Schenk of the Lunar and Planetary Institute and Jeff Moore of NASA’s Ames Research Center modelled Dione’s surface using digital elevation models (DEMs). Their results indicate volcanism has been a major force in shaping Dione’s surface. “We don't see giant shield volcanoes belching lavas,” says Schenk. ”Instead we see smooth plains with low crater densities.” These plains are the hallmark of cryovolcanism, which manifests itself as an outpouring of icy liquids from a moon’s interior. How it works The DEMs used by Schenk and Moore reveal Dione’s cryovolcanic plains to be higher than the surrounding terrain, suggesting they may have been emplaced in a high viscosity flow similar to terrestrial glaciers sometime within the last 2 billion to 4 billion years. Cryovolcanism requires a heat source to drive liquids to the surface. At present the mechanism for this heat engine is not fully understood but the two leading contenders are radioactive decay and gravitational flexing. “As far as the source of the heat, well that’s the big question. It is clear that some of the craters (on Dione) have been severely modified by high heat flow, not unlike parts of Enceladus. Perhaps these satellites (Dione and Enceladus) were very hot to begin with and had continued tidal heating to keep them warm,” Schenk told SPACE.com. This tidal heating of these moons interiors would be caused by Saturn’s strong gravitational pull as well as help from Dione and Enceladus’ orbital resonance; Enceladus completes two orbits of Saturn for every one achieved by Dione. Gravity pulls on the moons from different angles during their <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 24, 2007

A perspective view over volcanic terrain seen in a new digital elevation model, with ridges in foreground and large impact basin in background. The elevations are exaggerated for effect. Red is high and blue is low. Credit: Paul Schenk/LPI, NASA Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 24, 2007

Thermally modified impact craters seen in the new digital elevation model. The elevations are exaggerated for effect. Red is high and blue is low. Credit: Paul Schenk/LPI, NASA . Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 24, 2007

Tectonic faults and craters on Saturn's icy moon Dione are revealed in this color-enhanced image that mixes infrared, ultraviolet and green light observations. The color variations might be caused by subtle differences in the surface composition or the sizes of grains making up the icy soil, but scientists aren't sure. Credit: NASA/JPL/Space Science Institute. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 24, 2007

This very detailed image taken during the Cassini spacecraft's closest approach to Saturn's moon Dione on Dec. 14, 2004 is centered on the wispy terrain of the moon. To the surprise of Cassini imaging scientists, the wispy terrain does not consist of thick ice deposits, but rather the bright ice cliffs created by tectonic fractures. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo. For more information, about the Cassini-Huygens mission visit, http://saturn.jpl.nasa.gov and the Cassini imaging team home page, http://ciclops.org. Image Credit: NASA/JPL/Space Science Institute Full resolution image can be seen here. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

portercc · Apr 25, 2007

One of my favorite moons. I believe we should be getting some images of Dione this week. A pass of 71,000 on April 24th.

3488 · Apr 25, 2007

Post deleted by 3488. Image did not attach! Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

Whilst not fantastically close to Dione, 71,000 KM will still yield some high resolution images, about 900 metres - 1 KM, per pixel, so good enough to image any interesting terrain. Also close enough, to check the local environment, elevated dust levels, outgassing, etc. When the images are in, I will post some on this thread. Dione is turning out to be a very interesting moon of Saturn, quite different in many respects to the stereotypical cratered ice ball. Quite like the one below from a distance of 273,964 kilometers on : Monday 9th April 2007. Clearly shows smoother areas with only smaller imapct craters, a large filled basin & numerous canyons & valleys. Like most fairly large ice moons (Iapetus a notable exception), Dione lacks tall mountains. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

Also this one, taken immediately afterwards, long exposure, looking for plumes, etc??? Dione is vastly overexposed, but this image can reveal any activity along the limb & terminator. Image obtained: Monday 9th April 2007. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

As promised new Dione images are coming in from the Cassini encounter of: Tuesday 24th April 2007. Literally just appeared on the Cassini website. N00081677.jpg was taken on April 24, 2007 and received on Earth April 25, 2007. The camera was pointing toward DIONE at approximately 107,675 kilometers away, and the image was taken using the CL1 and IR3 filters. This image has not been validated or calibrated. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

N00081692.jpg was taken on April 24, 2007 and received on Earth April 25, 2007. The camera was pointing toward DIONE at approximately 111,007 kilometers away, and the image was taken using the CL1 and IR3 filters. Just a co-incidence I know, the canyons at the 11 o'clock position are very similar to those on the Uranus moon Ariel!!! Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

N00081685.jpg was taken on April 24, 2007 and received on Earth April 25, 2007. The camera was pointing toward DIONE at approximately 109,502 kilometers away, and the image was taken using the CL1 and GRN filters. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 25, 2007

N00081672.jpg was taken on April 24, 2007 and received on Earth April 25, 2007. The camera was pointing toward DIONE at approximately 106,650 kilometers away, and the image was taken using the CL1 and CL2 filters. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

MeteorWayne · Apr 25, 2007

I think I need to order another box of WOW's. WoW!! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

docm · Apr 25, 2007

Double WOW's <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

Swampcat · Apr 25, 2007

Color image of Dione from April 25th images (IR1, GRN and UV3 filters): <div class="Discussion_UserSignature"> ------------------------------------------------------------------- "I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."Thomas Jefferson </div>

brellis · Apr 25, 2007

hi borman It's always a joy to get a lurker's p.o.v. of your thought process. Thanks for sharing it here! A possible way to sort out the difference is to note all the additional different products coming from Enceladus, consistent with a subsurface release of water when compared to what products are being cast off from Dione as compared to what we see on the surface of Dione. There were some comparative measurements as of the announcement of possible Dione outgassing. IIRC, the spectrum of the Dione outgassing was "cleaner" {icier?} than that from Enceladus. My guess is that Enceladus' outgassing is 'dirty' because it is physically ejecting its material, while Dione's output is 'cleaner' because of a different, relatively passive process.* *This is a guess. I know I'm waay over my head here. <img src="/images/icons/smile.gif" /> I skimmed through the outgassing thread, found this comment from you: impacts great or small can dredge up fresher crystal ice. There may be ice spewn from interiors via cryovolcanism from a moon or second hand ice from another moon such as Enceladus. That's what I would've said, if I knew how to put it! <div class="Discussion_UserSignature"> I'm a recovering optimist - things could be better. </div>

portercc · Apr 26, 2007

Our old friend Ariel. Nice job Andrew!

3488 · Apr 26, 2007

Post deleted by 3488 <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 26, 2007

Hi MeteorWayne & portercc. I will keep an eye out for more images later. We do not have the ones from closer in yet (unless closest approach was over the night hemisphere)!!! The Uranus moon Ariel seems to share many traits. Did you ever see the thread I started ages ago on this? Thanks swampcat for your colour image. Dione could well join the list of geologically active worlds in out Solar System. A major find!! Below I have attached an image showing Dione & Ariel canyons to the same scale. The limb of Ariel does show some tall mountains where as Dione does not. The canyons on Ariel are larger, but generally are the same shape & form as those on Dione. Both Ariel & Dione are about the same size & density of each other!! Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 26, 2007

Global image of Dione, just in. N00081693.jpg was taken on April 24, 2007 and received on Earth April 26, 2007. The camera was pointing toward DIONE at approximately 195,349 kilometers away, and the image was taken using the CL1 and CL2 filters. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 26, 2007

Close up of one shot of Dione showing a relatively smooth terrain & a curious feature at the bottom just left of centre. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 27, 2007

N00041246.jpg was taken on October 11, 2005 and received on Earth October 12, 2005. The camera was pointing toward DIONE at approximately 1,360 kilometers away, and the image was taken using the CL1 and CL2 filters. This image I know was a while back in October 2005, but is the highest resolution image yet of Dione. About 10 metres per pixel. What is curious are the shallow valleys running from top left to bottom right, with small ridges running at right angles to them. Clearly this small patch is very old, owing to the number of tiny impact craters, exposing 'cleaner' ice. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Apr 27, 2007

N00041245.jpg was taken on October 11, 2005 and received on Earth October 12, 2005. The camera was pointing toward DIONE at approximately 1,360 kilometers away, and the image was taken using the CL1 and CL2 filters. Another ultra close image of Dione. About 10 metres per pixel. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

h2ouniverse · May 8, 2007

Dear all, Looking for info in Ariel I incidentally fell on this discussion. I recently attended a presentation from MK Dougherty from Imperial College(*). She was recalling that their analysis of Saturn's plasma flow Cassini measurements had evidenced a plume from Enceladus (via the asymmetrical deviation of the plasma by Enceladus) long BEFORE the optical observation. And, that they measure a similar although less ample phenomenon on Dione... That is especially encouraging for the future confirmation of venting and activity on Dione. And also a reminder that we shall look under every stone: all icy bodies deserve close looks! Regards. (*) EGU2007-A-05413; PS3.0-1TH3O-006 Dougherty, M. K.; Khurana, K. K.; Neubauer, F. M.; Russell, C. T.; Saur, J.; Leisener, J. S.; Burton, M. E. Discovery of a Dynamic Atmosphere at Enceladus from Cassini Magnetometer Observations

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