Computer model explains sustained eruptions on icy Enceladus

March 28, 2016
This enhanced color view of Enceladus shows much of the southern hemisphere and includes the south polar terrain at the bottom of the image. Scientists at the University of Chicago and Princeton University have published a new study describing the process that drives and sustains this moon of Saturn's long-lived geysers. Credit: NASA/JPL/Space Science Institute

The Cassini spacecraft has observed geysers erupting on Saturn's moon Enceladus since 2005, but the process that drives and sustains these eruptions has remained a mystery. Now, scientists at the University of Chicago and Princeton University have pinpointed a mechanism by which cyclical tidal stresses exerted by Saturn can drive Enceladus's long-lived eruptions.

"On Earth, don't tend to continue for long," said Edwin Kite, assistant professor of geophysical sciences at UChicago. "When you do see eruptions that continue for a long time, they'll be localized into a few pipelike eruptions with wide spacing between them."

But Enceladus, which probably has an ocean underlying its icy surface, has somehow managed to sprout multiple fissures along its south pole. These "tiger stripes" have been erupting vapor and tiny frost particles continuously along their entire length for decades and probably much longer.

"It's a puzzle to explain why the fissure system doesn't clog up with its own frost," Kite said. "And it's a puzzle to explain why the energy removed from the water table by evaporative cooling doesn't just ice things over."

What's needed is an energy source to balance the evaporative cooling. "We think the energy source is a new mechanism of tidal dissipation that had not been previously considered," Kite said. Kite and Princeton's Allan Rubin present their findings the week of March 28 in the Early edition of the Proceedings of the National Academy of Sciences.

This close-up view of Saturn's moon Enceladus show a distinctive pattern of continuous, slightly curved and roughly parallel faults within the moon's southern polar latitudes. Informally called 'tiger stripes' by imaging scientists, they mark the source of the moon's long-lived geysers. Credit: NASA/JPL/Space Science Institute

"I was very happy to see this new work by Kite and Rubin that brings to the fore a process that had escaped notice: the pumping of water in and out of the deep fractures of the south polar ice shell by tidal action," said Carolyn Porco, head of Cassini's imaging science team and a leading scientist in the study of Enceladus.

Astrobiology experiment

Enceladus, which Kite calls "an opportunity for the best astrobiology experiment in the solar system," serves as a leading candidate for extraterrestrial life. Cassini data have strongly indicated that the cryovolcanic plumes of Enceladus probably originate in a biomolecule-friendly oceanic environment.

Cryovolcanism may also have shaped the surface of Europa, one of Jupiter's moons. "Europa's surface has many similarities to Enceladus's surface, and so I hope that this model will be useful for Europa as well," Kite said.

One of the problems that attracted Kite and Rubin was the anomalous tidal response of the Enceladus eruptions. The eruptions reach their peak approximately five hours later than expected, even when taking into account the 40 minutes needed for the erupted particles to reach the altitude at which Cassini can detect them. Other scientists had previously suggested reasons for the lag, which included a delay in the eruptions as well as a squishy, slowly responding ice shell.

Computer model explains sustained eruptions on icy moon of Saturn
Jets of icy particles burst from Saturn's moon Enceladus in this sequence of four images taken from the Cassini spacecraft on Nov. 27, 2005. The geysers of Enceladus continue to erupt today. Credit: NASA/JPL/Space Science Institute

"The new proposal is really a way to get a delay in the eruptions. You really don't need to propose any terribly squishy ice shell to do it," Porco said.

Kite and Rubin also wanted to know why Enceladus maintains a base level of cryovolcanic activity, even when at that point in its orbit where the fissures should clamp shut and curtail the eruptions. Other key questions: Why does the volcanic system generate five gigawatts of power instead of a lot more or a lot less? Why don't the eruptions frost over or freeze over?

The Kite-Rubin model of the Enceladus plumbing system seems to answer them all. Their model consists of a series of nearly parallel, vertical slots that reach from the surface down to the water below. They applied Saturn's tidal stresses to their model on a desktop computer and watched what happened.

The tricky part

"The only tricky part quantitatively is calculating the elastic interactions between the different slots and the varying water level within each slot as a response to the tidal stress," Kite explained. The width of the slots affects how quickly they can respond to the tidal forces. With wide slots, the eruptions respond quickly to tidal forcing. With narrow slots, the eruptions occur eight hours after the tidal forces reach their peak.

"In between there's a sweet spot," Kite said, where tidal forces turn water motion into heat, generating enough power to produce eruptions that match the observed five-hour lag. Porco called it "the best thing in my mind about this new work."

Tidal pumping heats the water and the ice shell via turbulence. Kite and Rubin have proposed that new Cassini data can test this idea by revealing whether or not the in the south polar region is warm.

"If the new mechanism is a major contributor to the heat coming from the fractures, then the south polar ice in between the fractures may in fact be cold," Porco said. "The jury is still on out on this until the results from the final Enceladus flybys of last year are fully analyzed."

Kite and UChicago geophysical sciences Prof. Douglas MacAyeal are interested in studying an Earth analogue to the Enceladus geysers. A crack has formed across a section of the Ross Ice Shelf in Antarctica, partially breaking it away from the continent.

"In that crack you have strong tidal flow, so it would be interesting to see what a real ice sheet does in an environment that's analogous in terms of the amplitude of the stresses and the temperatures of the ice," Kite said.

Explore further: Image: Enceladus and Saturn's rings

More information: Sustained eruptions on Enceladus explained by turbulent dissipation in tiger stripes, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1520507113

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24 comments

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cantdrive85
1.8 / 5 (10) Mar 28, 2016
The reason Enceladus remains so "mysterious" is due to the fact they have continued to ignore the one mechanism that is most likely the cause of the plumes, electrical discharge machining. The source of the electric current has already been found, all that needs to be realized is that it "actually does something".
http://www.nasa.g...420.html
wduckss
1.4 / 5 (10) Mar 28, 2016
I do not know why smart scientists persistently pushed impossible things and trying to pump her the truth, which is actually a lie?
Beneath Antarctica is also the molten core of the Earth and the temperature is larger for 100 ° C of Enceladus and there is no indication of geysers etc.
In Antarctica have water (as opposed to Enceladus) and there is silence.
How many times do they should be repeated the lie that being accepted as true?
HannesAlfven
1 / 5 (5) Mar 28, 2016
It's ironic that they posted the animated gif which shows the "geysers" moving independently of the land features. You'd think more people would find this unusual. Yet, nobody blinks.
britton_beckham
2.5 / 5 (8) Mar 28, 2016
Computer models -- get used to it people, it's the science of the future. Forget real data... why would you need it why you can generate your own?
matt_s
4.7 / 5 (15) Mar 28, 2016
@HA

Seems to just be the changing relative position of the geyser to the spacecraft, not that the geysers location on the surface is actually moving. But hey, always a conspiracy, right?
jonesdave
4.5 / 5 (8) Mar 29, 2016
The reason Enceladus remains so "mysterious" is due to the fact they have continued to ignore the one mechanism that is most likely the cause of the plumes, electrical discharge machining. The source of the electric current has already been found, all that needs to be realized is that it "actually does something".
http://www.nasa.g...420.html


Lol. Again. And what parts of the electromagnetic spectrum would this EDM be seen in? And why hasn't it?
What temperatures would show up where the non-existent EDM isn't happening? Certainly not the ones that have been seen.
What ro-vibrational state would the H2O be in if produced by a 'hot' mechanism? Why isn't it?
Learn to do a bit of research b4 talking BS.
wduckss
1 / 5 (2) Mar 29, 2016
The form is recognizable. Compression (holding force) and stretching takes place perpendicular to the equator, the heated (less cold) material goes to the poles (quasars, pulsars, stars, etc.).
The action of the force and duration of the process is long lasting, bursts of matter depend on the composition of the body.
FredJose
2.1 / 5 (7) Mar 29, 2016
Other key questions: Why does the volcanic system generate five gigawatts of power instead of a lot more or a lot less? Why don't the eruptions frost over or freeze over?

Herein lies the rub of the mystery. Since the tidal energy is not enough to give continuous heating, there has to be another reason why it doesn't freeze over. Some other source of energy within the planet itself must be responsible. And finding a reason for its existence will be a major, major headache to solve - given that Enceladus is supposedly billions of years old.
antialias_physorg
4.7 / 5 (14) Mar 29, 2016
Computer models -- get used to it people, it's the science of the future. Forget real data... why would you need it why you can generate your own?

Did you even read the article? This isn't just computer models. It matches observation (i.e. real data gathered beforehand).
Whether the model pans out is now up to what other effects it predicts and whether these effects match further observation. This paper proposes such a testable model.

That is how ALL of human knowledge is gathered. You make an observation...you make a mental model of what might be the cause....you check the model against further observation. Whether the mental model is just formulas on paper of a computer model (which is nothing but formulas coded into a program) makes no difference.

It's not the 'science of the future'. It's just how science has always been done: Always use the best tools available.
wduckss
1 / 5 (4) Mar 29, 2016
FredJose
You are on the right path. Instead of another source that generates temperature, include other materials (particles) The temperature at Enceladus is: min. -240 ° C, average -198 ° C. Nitrogen is liquid at a temperature of -209 ° C to -195 ° C.
Not need further source because there are already conditions for discharge of nitrogen from admixture especially because the max. temperature of -128 ° C.
Tuxford
1 / 5 (5) Mar 29, 2016
Other key questions: Why does the volcanic system generate five gigawatts of power instead of a lot more or a lot less? Why don't the eruptions frost over or freeze over?

Herein lies the rub of the mystery. Since the tidal energy is not enough to give continuous heating, there has to be another reason why it doesn't freeze over. Some other source of energy within the planet itself must be responsible. And finding a reason for its existence will be a major, major headache to solve - given that Enceladus is supposedly billions of years old.


In SQK, it is genic energy from photon blue shifting entering our observable universe deep within the cores of larger bodies. The larger the body, the more energy generated. The extreme case is quasars. Explains why Jupiters and Plutos are too hot as well.
HannesAlfven
1.9 / 5 (9) Mar 29, 2016
Re: "Lol. Again. And what parts of the electromagnetic spectrum would this EDM be seen in?"

You do realize that this is like asking what frequency your blow torch runs at, right? Probably not the correct question to be asking ...

Re: "And why hasn't it?"

Actually, the evidence in support of EDM is very large, and spans numerous topics and solar system bodies. What is confusing the planetary scientists is that it's slightly different on each planet that it occurs.

Re: "What temperatures would show up where the non-existent EDM isn't happening?"

Not sure where you're going with that.

Re: "What ro-vibrational state would the H2O be in if produced by a 'hot' mechanism? Why isn't it?"

You seem eager to find reasons to not believe it. But, you've obviously not spent any time trying to understand it first. You're off on the basic details of the claim.

Re: "Learn to do a bit of research b4 talking BS."

I did.
matt_s
5 / 5 (8) Mar 30, 2016
You do realize that this is like asking what frequency your blow torch runs at, right? Probably not the correct question to be asking ...


Blow torch operates in visible light and infrared, correct? If there was a giant blow torch, you could observe it operating. I think that's the point he's getting at. We haven't seen EDM.

Actually, the evidence in support of EDM is very large, and spans numerous topics and solar system bodies


And yet, any feature attributed to EDM can be explained by another cause.

Not sure where you're going with that.


I agree. I think power required for these EDM processes would be a much more interesting number. Just how powerful would these events need to be to carve claimed features? (Order of magnitude is fine)

I did.


Then apply that to all your comments. (Particularly your first one on this page..)

Captain Stumpy
4 / 5 (8) Mar 30, 2016
@ha
power required for these EDM processes
that is the all important note to remember... this is also something that can be determined by extrapolating from the plasma physics, and it is why the eu fails every time they assume it is the cause of their cratering regardless of the observed impacts.

this is why your EDM theory fails as well. not saying it is not possible, just not probable for the bulk of the impact craters (and again, it would leave a *lot* of evidence behind that could be used to demonstrate the source of cratering, as told to you and cd in the past, but ignored)

the reason MS trumps eu is simple: evidence
you got none
Learn to do a bit of research b4 talking BS
I did
reading a soliloquy of your deluded fundamental religious leadership is not research, nor is searching your fundie sites

research starts in places like this: http://ocw.mit.ed...y-topic/

it also includes reputable source material
not fundie links
jonesdave
5 / 5 (5) Mar 30, 2016

I did.


Yep; at Dunderdolts.
Is it cold EDM? It would need to be, because the places where the EU idiots claim it to be happening (i.e. comets & Enceladus etc) have had temperature measurements made of the areas in question. Does it operate at, say, 200K? Didn't think so.
I suggest you do some research on the ro-vibrational levels of molecules. Shouldn't take more than a few months.
Then do some research on the electromagnetic spectrum, and where these discharges and various other electrical woo should show up, i.e. x-ray, radio, EUV, FUV etc. And then ask why we don't see it.
And then ask why there is still zero evidence for it.

cantdrive85
1 / 5 (4) Mar 30, 2016
Blow torch operates in visible light and infrared, correct? If there was a giant blow torch, you could observe it operating. I think that's the point he's getting at. We haven't seen EDM.

He didn't say it should look like a blow torch, he used an analogy. Most folks jump to the conclusion they understand what we should be seeing regarding EDM. EDM doesn't only occur in arc mode discharge, sputtering is an example of EDM that doesn't require arc mode discharge. As Wiki "reports", an electric discharge is any flow of electric charge through a gas, liquid, or solid. Of course this includes plasma as well, you know the other 99.999% of the Universe. Not surprisingly Wiki omits the most common state of matter known, plasma. Charge density is the concern, not frequency or temperature or brightness.
cantdrive85
1 / 5 (4) Mar 30, 2016
Is it cold EDM?

Could very well be. Can you show the temperature parameters of EDM? Or are you trying to apply your extensive knowledge of plasma processes ( like sputtering and electrochemistry in plasmas)? JA!
matt_s
5 / 5 (6) Mar 30, 2016
He didn't say it should look like a blow torch, he used an analogy.


Of course, and I was pointing out the analogy doesn't work. These processes must be visible?

EDM doesn't only occur in arc mode discharge, sputtering is an example of EDM that doesn't require arc mode discharge.


Do you have a video of these processes happening naturally on Earth? If not, then why should I consider that idea, when erosion explains the same features (and can be observed in real time?)

Here's a specific question. What kind of power output, over what kind of time scale, would be required to carve a feature the size of the Grand Canyon?
cantdrive85
1 / 5 (3) Mar 31, 2016
Do you have a video of these processes happening naturally on Earth?

Earth's atmosphere and EM environment is slightly different than Enceladus', there is your inapplicable analogy. There are a number of different examples of electric discharge occurring on Earth, such as lightning, ball lightning, tornadoes, dust devils, hurricanes, aurora, wind, earthquake lights, St. Elmo's fire, among others.

If not, then why should I consider that idea, when erosion explains the same features (and can be observed in real time?)

Because erosion fails to explain the Grand Canyon, unless water really does flow up hill. Or unless gigantic side canyons can be eroded without similarly significant tributaries. There is also no explanation for the missing 1300 cubic kilometers of material. That theory has it's own shortcomings.
Da Schneib
5 / 5 (4) Mar 31, 2016
When you make a theory, and it turns out to work in unrelated fields, that's called "consilience," and it's a clear indicator of a really good theory.

It doesn't matter if the theory is written as equations on paper, or encoded as equations on a computer. The entire point of computers is to do what you can do on paper without killing trees.

People who whine about computer models don't understand computers.
Captain Stumpy
5 / 5 (4) Mar 31, 2016
There are a number of different examples of electric discharge occurring on Earth
@cd
yeah, well... here is a point
they're far more likely to happen on Earth for many reasons from the atmosphere to more, but you still don't see any high energy plasma discharges capable of forming the grand canyon
Why is that?
Because erosion fails to explain the Grand Canyon
and you have absolutely zero evidence supporting that one (still)

more to the point, your "plasma discharge" delusion would leave a "lot" of evidence behind that we not only don't see, but can't find *any* evidence of whatsoever

that is one major problem your whole eu idiocy has - that the evidence for your claims is not present supporting you

another problem is prediction failures (shall i link some of your highlights?)

yet another problem is feasibility or observation

shall i go on?
cantdrive85
1 / 5 (2) Mar 31, 2016
When you make a theory, and it turns out to work in unrelated fields, that's called "consilience," and it's a clear indicator of a really good theory

That's why EU Theory is head and shoulders above all others, "consilience". From cosmology to biology, geology to human historical record, the EU is unmatched in "consilience" across disciplines.

People who whine about computer models don't understand computers

People who don't understand how computer models are generated using preconceived notions which allows them to build the "models" to produce the desired outcomes seem unaware it is not science.
matt_s
5 / 5 (4) Mar 31, 2016
@CD

I repeat.
Here's a specific question. "What kind of power output, over what kind of time scale, would be required to carve a feature the size of the Grand Canyon?"

Why don't we see features like this being carved today? For people who are all about seeing real world results... seems like an epic failure here. You list some phenomenon, but none have ever done anything like what you're claiming happened with the Grand Canyon. Where's the evidence?
FineStructureConstant
5 / 5 (4) Mar 31, 2016
...lightning, ball lightning, tornadoes, dust devils, hurricanes, aurora, wind, earthquake lights, St. Elmo's fire, among others...
Among others? Pixie farts? Jello balls? Fire ants? Muons? Yet another cluster of discarded EU theories hitting the dust at terminal velocity?

OK, so not counting those who have been abducted by bug-eyed aliens, all those who have seen one/any/all of the above phenomena create a canyon: raise your right hand.

Come on, now, don't be shy...

Guys?

Uhhh, guys.........

[Exit stage right, holding candle.]

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