Enceladus, the Europa of Saturn

[silylene old]

And Enceladus for comparison: <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[CalliArcale]

The striations on Dione seem different from Enceladus' tiger stripes, though. They're fractures, and relatively recent ones to boot since they have very jagged and brilliantly white surfaces -- even where they run through the dark region on the trailing hemisphere of Dione. There are fractures that appear much older, visible in that picture. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"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."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[thermionic]

>>All the major planets have rings <br />Does Jupiter have a ring too?

 

[yurkin]

I never liked the Impact Theory for the Enceladus warm region. Anything that is time dependant is unlikely simply because we have to be there at the right point in its development. Its simply more likely that the moon has always been like how it is now rather then that it recently became that way.

 

[chew_on_this]

<font color="yellow"> for the same reason the moon has no vulcanism. </font><br /><br />Umm... cryo-vulcanism it has.<br /><br /><font color="yellow">We have no evidence of tidal effects, esp. not with Saturn, to create enough heat.</font><br /><br />Funny the scientists believe this is the cause, but I'll take Steves word on it!<br />

 

[bad_drawing]

Plumes imaged coming from Enceladus!<br /><br />http://saturn.jpl.nasa.gov/multimedia/images/raw/raw-images-details.cfm?feiImageID=54845<br /><br />The size and shape of the plumes makes me think that your assertion earlier in this post about Enceladus being the source of the e-ring could very likely be true.<br /><br />

 

[chew_on_this]

Enceladus may be an easier candidate than Europa for a heat sinking probe to explore the depths and composition of the warm southern region. Assuming the crust is that much thinner to allow plumes.

 

[jatslo]

Be sure to tag stevehw33 hard when he gets here. <img src="/images/icons/wink.gif" />

 

[bonzelite]

"I never liked the Impact Theory for the Enceladus warm region. Anything that is time dependant is unlikely simply because we have to be there at the right point in its development. Its simply more likely that the moon has always been like how it is now rather then that it recently became that way."<br /><br />---i agree. enceladus in all likelihood has been that way for an ongoing period of time. probably for centuries. i never ever thought an impact created the fissures and jets of water. in my opinion, the structures do not in any way suggest this. there may be (have been) espisodes of eruptions to the surface from a variety of locales; we just happen to be seeing this one. <br /><br />as i generalize, causation of everything we see out there by "impacts" is, to me, highly overrated: objects are too remote from each other in space for impacts to play the role that they are assumed to. it appears that there is a knee-jerk reaction to immediately claim that, by some measure, an impact created this or that. <br /><br />enceladus raises far more questions than it answers. so far, the whole tour of Saturn, though just really begun, has rendered some of the most intriguing celestial objects and phenonmena i have yet seen. if enceladus is actually generating it's own heat, which it just might be, then this entirely throws a wrench into conventional wisdom. <br /><br />and the spiral ring of saturn is quite hilarious. it is as if the cosmos were playing a big joke on all of us, reminding us that we don't really know much of anything. <br /><br />

 

[bonzelite]

<font color="yellow">The conclusion of the article: <br /><br />"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!"</font><br /><br />radioactive heat mole impactor is a creative and cute idea, but seems nearly totally unbelievable and inplausible --when in doubt, say it is from an impact event. <br /><br />this heat mole, then, had to nearly perfectly strike the south pole dead-on. i think we need to shave with a certain razor tonight. <br /><br /><br />

 

[bonzelite]

<font color="yellow">It sure seems like we need an extraneous energy source - the amount and localization of heat from Enceladus' hot spot certainly rules out standard tidal or accretionary radioactive heating models! The density of Enceladus (as I mentioned in this thread) implies this moon is mostly water ice, constraining theoretical radioactivity to only small localized regions (necessitating higher concentrations of radioactive materials) as the total rock mass is apparently rather low. The fact that there is any noticeable heating on such a small moon is flat out amazing. </font><br /><br />thank you. <br /><br />every explanation will be proposed except the one that makes the most sense. no razors will be used at all.

 

[bonzelite]

<font color="yellow"> I would certainly be curious to hear your proposal to explain what we are seeing at Enceladus when you get the chance..... it should make for some interesting reading.</font><br /><br />the reading will become more interesting once there is more data; speculation is all we have at this point. some of it is far off the mark, some of it is closer, perhaps, to the general reasons for it's happening. <br /><br />i ask: why is the south pole so warm? nevermind the burrowing radioactive mole, perfectly impacted at the bullseye of the south pole --but just ask the question first: why is it so warm there, notably a hot spot? <br /><br />moreover, what else could be responsible for this polar heat signature? <br /><br />has the north pole been temperature mapped as has the south? if so, what is the data from that mapping?<br /><br />is Enceladus embedded in a plasma torus, as is Io at Jupiter? and what are the similarites between Enceladus to Io? what are the differences? <br /><br /><br /><br /> <br /><br /><br />

 

[bonzelite]

okee dokee. we shall resume afresh tomorrow.

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>I would expect impacts to be much more frequent there than in the inner solar system, as various studies have determined.<p><hr /></p></p></blockquote><br /><br />That expectation is well supported by the phenomenally battered surfaces of many of Saturn's moons and the shockingly large number of really huge craters.<br /><br />I know this has been bandied about before, but one thing that's been suggested is that Enceladus was struck so violently that it was almost completely liquified. It could've taken a heck of a long time for it to cool down, and maybe the south pole is just the last spot to cool down; its probably not completely uniform inside, so it seems plausible for cooling to occur somewhat irregularily. But I'm no physicist. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"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."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[astrophoto]

Are the temps recorded higher than the freezing point of water? I wonder that if the body was mostly water under a thick layer of ice that water might retain it's liquid form for quite some time under that 'insulation' similar to an igloo -- a minor heat source could keep it that way for quite a period. Then add an impact event and you get a geyser.... the impact wouldn't necessarily have to have happened on the South Pole, I could see it happen elsewhere and simply 'crack the egg' at the weakest point.

 

[silylene old]

Enceladus already gets a significant amount of tidal heating due to its slightly egg-shape, and possibly if it had an eccentric orbit in its past.<br /><br />+++<br /><br />Finally, I wish to propose that if the interior of Enceladus is non-symmetrically inhomogeneous, that this in itself should be cause significant tidal heating. For example, if there was a lump of a high density material within the moon, but off-center, this should cause a very high amount of tidal heating, located above the dense lump.<br /><br />My hypothesis does not require that the lump itself offer radioactive heating, nor does it require that the lump carry remnant heat from a long-ago meteorite impact.<br /><br />Simply, if a dense large lump is present off-center in the moon, the lump will interact gravitationally with Dione, Saturn and other moons to cause the ices and rock above and around it to heat significantly due to unequal gravitatinal flexing. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[bonzelite]

<font color="yellow">You mention how odd it is that the South Pole got hit and that somehow this is counter to the razor. But you got it backwards. <br /><br />Enceladus has a density that suggests it is primarily ice. Radioactive materials are usually much denser than ice. If a large dense shard were to hit and augment locally the mass of Enceladus, there would be a mass location imbalance due to the denser material. Like a gyroscope, the resulting rotation from the combined masses would seek to minimize the imbalance meaning the heavy end would prefer to be at one of the poles rather than the opposite extreme of being at the equator. In other words, wherever the impact occurred is going to become a pole because of the density difference of the impactor assuming there is a great difference in density between the impactor and Enceladus which is more likely if the impactor is radioactive. </font><br /><br />i follow this reasoning and it makes sense. it still seems too complicated an idea, the whole "mole" thing. why would it's greater density sink to the south pole and not settle out in the middle of the body, no matter where it hit, then? opposite extreme, to me, is skewed to one of the poles. middle is balanced. <br /><br />i will reiterate that i am not a physicist or astronomer. so i'm going on individual assessment based upon layman knowledge of high school level physics. so i am by default simple-minded about these things. and i know that the complicated answer is sometimes the correct one. <br /><br />at least the plumes are beautiful. i do know that. <img src="/images/icons/wink.gif" /><br />

 

[bonzelite]

sily, your ideas are interesting.

 

[silylene old]

<font color="yellow">I've seen several recent estimates of the rocky material pointing to a core diameter of 95 -150 km!</font><br /><br />My hypothesis is that this core is either 1) <i>off-center</i>; 2) <i>non-spherical</i> or 3) there is a lump of inert dense rock or inert metal between the core and the south pole.<br /><br />Either way, I am rather sure that an asymmetric inhomogenous mass distribution would grealty amplify tidal wobbles and cause much greater heating. I would love to see a dynamical model of my hypothesis. But I am sure my proposition is correct that this would cause significant tidal heating if it the moons' mass was asymmetrically inhomogenously distributed.<br /><br />Careful monitoring of Cassini trajectories as it passes near Enceladus should allow for modeling of the mass distribution in the moon - <i>if</i> the model that this data is fit to is sophisticated enough to allow for non-symmetric mass distributions, it may find exactly what I am predicting.<br /><br /><font color="yellow">All the information I've been able to find indicates that even given Enceladus' orbital resonance to Dione and proximity to Saturn, there is insufficient energy produced by tidal effects - even if former orbital perturbations are included. </font><br />Enceladus is non-spherical. It's a bit egg-shaped, thus there's a little wobble longitudinally, about 1 degree in extent every Enceladus day, based on current SPICE models. Would that little wobble be enough to generate at least some heating? <br /> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[silylene old]

<font color="yellow"> <i>Borman</i> The mechanism you propose seems it should be rather common considering the number of impacts giving rise to the opportunity for it to occur. <br /></font><br />Plutons were detected on the Moon under some of the largest craters and some locations of maria, which was one of the big surprises of Apollo. IIRC, Apollo 16 studied this in detail as it orbited the moon. These caused the orbiting spacecraft to show small but measurable changes in orbital velocity and height. Similarly, perhaps there is a very large pluton (batholith) near the south pole of Enceladus. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[silylene old]

<font color="yellow">Regelation <br /><br />I am aware that a rock does not need to be radioactive to sink through ice. A process known as regelation where pressure alone is sufficient: </font><br /><br />The gravitational force downwards on Enceladus is very weak. And it will be even less as you move towards the center. Perhaps this weak force prevents complete regelation? As you know, moons not that much less massive than Enceladus are often non-spherical, because the gravitational attraction is inadequate for regelation to occur.<br /><br />(btw, the center of mass of the Moon is offset by a few km from the geometric center) <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[bonzelite]

worlds are highly individualistic, as are people. look at the diversity of worlds at Jupiter. and that is only one system. look at the odd things around Saturn by the truckload. what may arise on one world may not on another. what is happening at Enceladus may be unique to it's conditions. <br /><br />this still leaves us not knowing what those conditions are. threre are now discovered "trinary" star systems with planets. and the press releases contest that "it shouldn't be there." but it is. Enceladus is being heated from inside and it should not be, according to conventional science wisdom. but it is. so i think conventional explanations for the plumes' occurrences are not applicable. <br /><br />

 

[bonzelite]

indeed.<br /><br />looking at the moon and it's highly altered surface, most of the southern hemishpere being smoothly wrinkled, with ridges, rilles, it appears that the process of machining it's surface has been going on for quite a long time. this makes a residual process from an impact event seem highly unlikely. unless it is a radioactive mole that did impact, the impact idea appears weak. <br /><br />a question, then, is can cassini in subsequent passes assess radioactivity in the southern hemisphere of Enceladus? and if it can, and proves negative in result, then that would rule that out, yes? <br /><br />i'm still not buying the impactor event because of the hot spot's bullseye location directly at the south pole. it's too perfectly happening there. and a migration TO the south pole by some rock inside of it seems unbelievable and counter-intuitive. <br /><br />very baffling whatever it is. there now needs to be an Enceladus probe. we need so many probes that it is frustrating to contemplate how many gigantic discoveries have been made in just the short past year. and how specific investigation of individual worlds must take place.

 

[chew_on_this]

Better clarify what moon you're talking about dingus. The thread is about Enceladus. You did not say lunar in your post. Tidal effects are mathmatically confirmable there copernicus. You and your "confirmation" gig. You need some new material.

 

[chew_on_this]

Pot, kettle, black.