Enceladus, the Europa of Saturn

jmilsom · Jul 23, 2005

I've just now seen these images for the first time. Amazing. Applause. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

chew_on_this · Jul 26, 2005

Some news on the recent close flyby: CASSINI IMAGING CENTRAL LABORATORY FOR OPERATIONS (CICLOPS) SPACE SCIENCE INSTITUTE, BOULDER, COLORADO http://ciclops.org media@ciclops.org Preston Dyches (720) 974-5859 CICLOPS/Space Science Institute, Boulder, Colo. Erica Hupp/Dolores Beasley (202/358-1237/1753) NASA Headquarters, Washington Carolina Martinez (818) 354-9382 Jet Propulsion Laboratory, Pasadena, Calif. For Immediate Release: July 26, 2005 CASSINI FINDS RECENT, UNUSUAL GEOLOGY ON ENCELADUS New detailed images taken by NASA's Cassini spacecraft of the south polar region of Saturn's moon Enceladus reveal distinctive geological features, and the most youthful terrains of any seen on Enceladus. These findings point to a very complex evolutionary history for Saturn's brightest, whitest world. Cassini's flyby on July 14 brought it within 175 kilometers (109 miles) of the surface of the icy moon. The close encounter revealed a landscape near the south pole littered with house-sized ice boulders, carved by tectonic patterns unique to Enceladus, and almost entirely free of impact craters. These features set the southerly region apart from the rest of the moon. The new image products can be seen at http://ciclops.org, http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. As white as fresh snow, Enceladus (505 kilometers, 314 miles across) has the most reflective surface in the solar system. Previous Cassini flybys have revealed that Enceladus, in contrast to the other icy moons of Saturn, possesses lightly cratered regions, fractured plains and wrinkled terrain. The new findings add to the story of a body that has

thechemist · Jul 26, 2005

"Boulder Strewn Surface" (July 26, CICLOPS update) "The tortured southern polar terrain of Enceladus appears strewn with great boulders of ice in these two fantastic views – the highest resolution images thus far obtained by Cassini on any world." ................... At the fine scale afforded by the narrow angle view, the surface is dominated by ice blocks between 10 and 100 meters across. The origin of these icy boulders is enigmatic. Scientists are interested in studying the sizes and numbers of the blocks in this bizarre scene, and in understanding whether terrain covered with boulders is common on Enceladus. ................... Image scale is about 4 meters (13 feet) per pixel in the narrow angle image and about 37 meters (121 feet) per pixel in the wide angle camera image" <div class="Discussion_UserSignature"> I feel better than James Brown. </div>

CalliArcale · Jul 26, 2005

<blockquote>In reply to:<hr />I think calling Enceladus the Europa of Saturn is bit like calling Titan and early Earth. It seems accurate only at first glance. Enceladus is clearly its own world and trying to learn about Encaldus by comparing it to Europa isn’t going to work.<hr /></blockquote> True, but it got people's attention to the thread, didn't it? <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

gavino · Jul 27, 2005

It is possible for a Ocean on Enceladus, but If I had to chose which one would have one I would chose Europa. <div class="Discussion_UserSignature"> gavinovz </div>

centsworth_II · Jul 27, 2005

From Chew-on-This's opening post of this thread: From Carolyn Porco:Everyone, "...Enceladus, a body that could be the `Europa of the Saturn System', with the potential of a sub-surface ocean." What's the fuss? Enceladus and Europa may share the similarity of both having a thick ice crust covering a water ocean. Both having young surfaces covered with telltale cracks and ridges. Whatever great differences there may be between them, these similarities are real and scientifically important. Carolyn Porco is a real scientist, not a blowhard, stevehw33. She may or may not regret her perhaps off-hand comment, but she shouldn't. As to comparing Titan and an early Earth. One of the major stated scentific reasons for exploring Titan was the possibility of learning something about what the early Earth's atmosphere may have been like. How similar is the atmosphere of Titan to that of early Earth? Is there any similarity at all? Noone knows, but the questions are scientifically valid. There are plenty of exagerated headline claims that get my goat, but comparing Enceladus to Europa and Titan to early Earth are not among them. <div class="Discussion_UserSignature"> </div>

centsworth_II · Jul 27, 2005

Do you mean your post of 2-19? If so, I'll reprint my comment from that time: The first post specifies that they could be similar in both having "...the potential of a sub-surface ocean". No other similarities are drawn. Your list is interesting but useless as an attack on this premise. Yes there are great differences between Enceladus and Europa, no argument there. There are also stiking similarities in apparent surface composition --ice crust -- and features. These similarities are important and may be important in learning more about both moons. <div class="Discussion_UserSignature"> </div>

chew_on_this · Jul 27, 2005

There's nothing sensationalistic about the comparison originally made. Both moons have the impression of rafting. Pretty simple. You're the one making the comparisons that aren't relevant to the original post. I think comparing Carolyn Porco to the Enquirer is just as irrelevant (and silly) as your comparisons.

yurkin · Jul 28, 2005

Wow, I never meant to start a controversy, at least not with this post. My point is that good scientist must confront new data without any prejudices about what they are going to find. This isn’t just true of planetary astronomy. If we view Enceladus with the preconception that it will be similar to Europa it will skew our perception of what we are seeing. Now it may turn out in retrospect that similarities between the two worlds do exist, but that’s besides the point of post. <img src="/images/icons/smile.gif" />

volcanopele2 · Jul 28, 2005

I think stevehw does have a point, that we must be careful when comparing worlds of vastly different sizes. True, some regions on Enceladus do look a lot like Europa. However, large portions of the surface, like the north polar region and much of the anti-Saturnian hemisphere, look nothing like Europa, being covered in craters, indicating a very old surface age. The craters in these regions also conflict with the possibility of a GLOBAL sub-surface ocean. Now, the very young terrains certainly don't rule out localized tidal heating. The tidal heating would be produced by Enceladus' orbit migrating in and out of resonance with Dione. This heating may not be enough to produce global resurface, but is instead concentrated some how into a few regions. In terms of the statement made by Carolyn, this came out of earlier imaging of terrain that showed remarkable similarity to Europa. This just points out the problems with doing science "by press release".

yurkin · Jul 30, 2005

Back to the topic Cassini Finds an Active, Watery World at Saturn's Enceladus July 29, 2005 (Source: NASA/JPL) Saturn's tiny icy moon Enceladus, which ought to be cold and dead, instead displays evidence for active ice volcanism. NASA's Cassini spacecraft has found a huge cloud of water vapor over the moon's south pole, and warm fractures where evaporating ice probably supplies the vapor cloud. Cassini has also confirmed Enceladus is the major source of Saturn's largest ring, the E-ring. "Enceladus is the smallest body so far found that seems to have active volcanism," said Dr. Torrence Johnson, Cassini imaging-team member at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Enceladus' localized water vapor atmosphere is reminiscent of comets. 'Warm spots' in its icy and cracked surface are probably the result of heat from tidal energy like the volcanoes on Jupiter's moon Io. And its geologically young surface of water ice, softened by heat from below, resembles areas on Jupiter's moons, Europa and Ganymede."

chew_on_this · Jul 31, 2005

July 29, 2005 More from CICLOPS: Dear Friends and Colleagues, During Cassini's closest pass to Enceladus two weeks ago, at a grazing altitude of 109 miles -- about half the altitude of the Space Station's flight above the Earth -- multiple instruments made the remarkable discovery that heat and water vapor are escaping from the interior along the prominent, `tiger stripe' fractures seen near the moon's south pole. The fact that such a small moon, only 500 km (300 miles) across, has a significant interior heat source and is evaporating through tectonic gashes in its surface comes as a great surprise, and is just the kind of long-awaited clue scientists were hoping for in understanding the nature of this bizarre little world. For more information, and the latest image release, visit ... http://ciclops.org Enjoy, Carolyn Porco Cassini Imaging Team Leader Director/CICLOPS Space Science Institute Boulder, CO How fricken cool is that!

chew_on_this · Jul 31, 2005

And its geologically young surface of water ice, softened by heat from below, resembles areas on Jupiter's moons, Europa and Ganymede." Gee, imagine that...

centsworth_II · Jul 31, 2005

"Gee, imagine that..." Indeed. <div class="Discussion_UserSignature"> </div>

tom_hobbes · Jul 31, 2005

Care to speculate on the possible implications? <div class="Discussion_UserSignature"> I wish I could remember But my selective memory Won't let me - Mark Oliver Everett </div>

silylene old · Jul 31, 2005

I can remember a couple of SDC members were rather adamant that this could not occur.... <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

tom_hobbes · Jul 31, 2005

Erm, so do I. How nature surprises... <div class="Discussion_UserSignature"> I wish I could remember But my selective memory Won't let me - Mark Oliver Everett </div>

chew_on_this · Aug 1, 2005

Care to speculate on the possible implications? Hmmm...implications...speculation...are you trying to bait me for a good thrashing by that particular poster? That being said, I guess if you could narrow down what I'm speculating about, I'd be glad to stick my neck out. Life perhaps? I can see it now...but It's cryogenically cold out there(said while wildly flailing arms)!

thechemist · Aug 1, 2005

There is a very good sum-up article at The Planetary Society : Enceladus' South Polar Stripes Spew "Warm" Water The conclusion of the article: "The discovery is thrilling. Recent activity on Enceladus has been considered a possibility since Voyager, but there is no known explanation for how a body as small as Enceladus can generate enough internal heat to drive active geology. Spilker grappled with the problem: "Radiogenic heating is impossible for a body the size of Enceladus, there might not be much heat left over -- and tidal heating, from what we understand about how the tidal heating works, that’s not enough." But there's hope for people who want to explain Enceladus, she said. "I think the key here is that it’s not a global heat source, it’s really concentrated at the south pole. And that might make the problem a little easier in that you only need a localized heat source. How it got there, why it’s still there, -- people are busy scratching their heads!" <div class="Discussion_UserSignature"> I feel better than James Brown. </div>

nexium · Aug 1, 2005

So Enceladus has a diameter of 500 kilometers and a density of 1.2 The latter suggests that it is 90% water and other volitiles, likely frozen, but possibly liquid or not completely rigid. Considering the large contients and larger oceans of Earth, I don't see why an anomolous south pole of Enceladus is such a surprise. If negligible convection occured for millions of years, even 0.000001% radioactive material could make the interior hot. This stored heat escaping in a few hundred years, could account for most of the observed including E ring. Conditions may have been much different 40 years ago, when the mount Polomar observitory gave us a much less detailed view of Enceladus. Neil

tom_hobbes · Aug 1, 2005

<img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> I wish I could remember But my selective memory Won't let me - Mark Oliver Everett </div>

CalliArcale · Aug 1, 2005

<blockquote>In reply to:<hr />"I think the key here is that it’s not a global heat source, it’s really concentrated at the south pole. And that might make the problem a little easier in that you only need a localized heat source. How it got there, why it’s still there, -- people are busy scratching their heads!"<hr /></blockquote> I'm sure this is one of the things they're pondering, but what is the possibility that its residual heat from a massive impact? It would have to have been so massive as to have liquified Enceladus, since there's no huge crater to give it away. Either that, or there's a huge crater hiding where it hasn't been seen yet. Is there a large part of Enceladus that hasn't been adequately imaged yet? <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

chew_on_this · Aug 1, 2005

I'm with Calli on this one. I believe it's most likely an impactor providing this localized heat. The fact that no crater is present is due to the resurfacing of the (crater)area by outflow. What possibly remains is the jiggy pattern of cracks due to residual heat jostling crust around.

chew_on_this · Aug 1, 2005

Let me clarify, fine, temps ARE cryonically cold ABOVE the surface. I think most of us agree that is a given. Now below the crust, that's were you fail to see the forest for the trees. All I can say is....

centsworth_II · Aug 1, 2005

The argument (Enceledus, the Europa of Saturn) is not whether Enceledus is cryonically cold or not. Europa is cryonically cold -- on the surface. The argument is whether Enceledus resembles Europa in having an ice crust overlaying a liquid ocean. I will concede that it looks like a global liquid ocean is out for Enceledus. Europa's subcrust ocean may be global or not, it is certainly more extensive than Enceladus'. The point is that both Europa and Enceledus are similar in having ice crust showing evidence of a liquid sea beneath. Whether the cause is the same for both moons -- tidal warming -- is the next big question. <div class="Discussion_UserSignature"> </div>

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