Europa's heaving ice might make more heat than scientists thought

April 14, 2016 by Kevin Stacey, Brown University
As the moon Europa's icy shell is pushed and pulled by Jupiter's gravity, it heaves up and down. That process creates enough heat, scientists think, to create a global subsurface ocean on Europa. Experiments by Brown University researchers suggests that this heating process, known as tidal dissipation, creates more heat in ice that scientists have generally assumed. The insight could help scientists model the thickness of Europa's icy shell. Credit: NASA/JPL

Jupiter's moon Europa is under a constant gravitational assault. As it orbits, Europa's icy surface heaves and falls with the pull of Jupiter's gravity, creating enough heat, scientists think, to support a global ocean beneath the moon's solid shell.

Now, experiments by geoscientists from Brown and Columbia universities suggest that this process, called tidal dissipation, could create far more heat in Europa's ice than scientists had previously assumed. The work could ultimately help researchers to better estimate the thickness of moon's outer shell.

The work is published in the June 1 issue of Earth and Planetary Science Letters.

The largest Jovian moons—Io, Europa, Ganymede and Callisto—were first discovered by Galileo in the early 1600s. When NASA sent spacecraft to Jupiter in the 1970s and 1990s, those moons proved to be full of surprises.

"[Scientists] had expected to see cold, dead places, but right away they were blown away by their striking surfaces," said Christine McCarthy, a faculty member at Columbia University who led this new research as a graduate student at Brown. "There was clearly some sort of tectonic activity—things moving around and cracking. There were also places on Europa that look like melt-through or mushy ice."

The only way to create enough heat for these active processes so far from the sun is through tidal dissipation. The effect, McCarthy says, is a bit like what happens when someone repeatedly bends a metal coat hanger.

"If you bend it back and forth, you can feel it making heat at the junction," she said. "The way it does that is that internal defects within that metal are rubbing past each other, and it's a similar process to how energy would be dissipated in ice."

However, the details of the process in ice aren't very well understood, and modeling studies that try to capture those dynamics on Europa had yielded some puzzling results, the researchers say.

"People have been using simple mechanical models to describe the ice," McCarthy said. While those calculations suggested liquid water under Europa's surface, "they weren't getting the kinds of heat fluxes that would create these tectonics. So we ran some experiments to try to understand this process better."

Working with Reid Cooper, professor of Earth, environmental and planetary sciences at Brown, McCarthy loaded ice samples into a compression apparatus. She subjected the samples to cyclical loads similar to those acting on Europa's ice shell. When the loads are applied and released, the ice deforms and then rebounds to a certain extent. By measuring the lag time between the application of stress and the deformation of the ice, McCarthy could infer how much heat is generated.

The experiments yielded surprising results. Modeling approaches had assumed that most of the heat generated by the process comes from friction at the boundaries between the ice grains. That would mean that the size of the grains influences the amount of heat generated. But McCarthy found similar results even when she substantially altered the grain size in her samples, suggesting that are not the primary heat-generators in the process.

The work suggests that most of the heat actually comes from defects that form in the ice's crystalline lattice as a result of deformation. Those defects, the research showed, create more heat than would be expected from the grain boundaries.

"Christine discovered that, relative to the models the community has been using, appears to be an order of magnitude more dissipative than people had thought," Cooper said.

More dissipation equals more , and that could have implications for Europa.

"The beauty of this is that once we get the physics right, it becomes wonderfully extrapolative," Cooper said. "Those physics are first order in understanding the thickness of Europa's shell. In turn, the thickness of the shell relative to the bulk chemistry of the moon is important in understanding the chemistry of that ocean. And if you're looking for life, then the chemistry of the ocean is a big deal."

McCarthy and Cooper hope that modelers will make use of these findings as they try to unravel the mysteries of Europa's hidden ocean.

"This provides modelers with a new physics to apply," McCarthy said.

Explore further: Faraway moon mimics Earth tectonics

More information: Christine McCarthy, Tidal dissipation in creeping ice and the thermal evolution of Europa, Earth and Planetary Science Letters (2016). DOI: 10.1016/j.epsl.2016.03.006

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HannesAlfven
1.6 / 5 (13) Apr 14, 2016
Piling speculation upon speculation, and building models to sell it ...
wduckss
1 / 5 (9) Apr 14, 2016
Science should instead speculation that later most taken as solid evidence, start doing your job and find ways how collect substantial evidence. Exist writers who are expert on fairy tales.
Similar stories are endlessly circulated about Pluto and where are they now?
Captain Stumpy
4.7 / 5 (23) Apr 14, 2016
speculation
@ha
not entirely - you can see the effects of gravity in our own Moon-Earth system alone and how the tidal forces affect the water on our planet

... plus we know that Jupiter is quite a bit more massive and thus has greater tidal forces (observed)

we can test those gravitational forces by experimentation as well
... you know, like using it to launch stuff past Jupiter or to brake

... or by watching things hit Jupiter

so ... what happened recently that would be able to determine the accuracy of our knowledge about things like tidal forces and roche limits?

wow! how about D/1993 F2 !

so this is not speculation so much as it is evidence based hypothesis generating a model

of course, if you can provide evidence refuting this, feel free to publish a peer reviewed paper in the next journal of "Earth and Planetary Science Letters" or even "Science" magazine

i look forward to that one... just remember to link it here when you publish
thanks
gkam
2.1 / 5 (15) Apr 14, 2016
Enceladus, a moon of Saturn, not only has the ocean, but evidence of hydrothermal activity under the ice, like the early Earth.

Since many of these moons blast their stuff into space, we may not need a lander or ice borer to find life.
HannesAlfven
2.1 / 5 (15) Apr 14, 2016
Re: "of course, if you can provide evidence refuting this, feel free to publish a peer reviewed paper in the next journal of "Earth and Planetary Science Letters" or even "Science" magazine"

"Scientists are educated nowadays in a habit of self-censorship. The system promotes self-repression in the spread of ideas, so most scientists, when writing a paper, think something like 'I think this and that, but I cannot say so in my paper because this will not pass the referee's control, so I will not say it'. This causes serious harm to creativity among people who dare to think new things."

- Martín López Corredoira: Cosmologist / Astrophysicist / Philosopher / Published 50 Academic Papers, Often as Lead
Captain Stumpy
4.6 / 5 (19) Apr 15, 2016
"Scientists...blah blah blah
@ha
ah... so one person makes a quote that you agree with, so obviously this applies to all of the sciences everywhere
I see

since when is opinion considered evidence equivalent to a peer reviewed journal study?

here are some more quotes:
"Baseball is 90% mental. The other half is physical" Yogi Berra
we can now determine that baseball has 140% in total reality because the opinion of the great Berra, right?

better yet - "A nickel ain't worth a dime anymore" Yogi Berra
this must mean the overall world state of inflation has increased to the point of detrimental and depreciatory misrepresented monetary allotments assigned to coins, and they then being destabilised due to inaccurate consolidated assignments of value insuring the destruction of the future economy, obviously

.

which brain told you that opinion was equivalent to empirical evidence, BTW?
the reptilian fast thinking brain?
SCVGoodToGo
3.9 / 5 (15) Apr 15, 2016
"Scientists are educated nowa TL;DR
- Martín López Corredoira


"Wise men make proverbs, but fools repeat them."
- Samuel Palmer (1805-80)
torbjorn_b_g_larsson
4.7 / 5 (14) Apr 15, 2016
Of course the trolls misrepresent an empirical input as 'model' and 'speculation' (which is it?), but neglect to note that there are and will be crafts measuring the thermal dissipation directly. (Such as Cassini.)

Add an ironic touch when one of them quotes a fringe scientist/philosopher. (Look at his home page!) Conflict of interest and severe misrepresentation, anyone!?

Meanwhile science marches on.

Despite the agitated screams of web trolls who doesn't recognize science, even less can accurately describe it, when it hits them in the face. "It is a tale. Told by an idiot, full of sound and fury, Signifying nothing."
gwrede
5 / 5 (8) Apr 15, 2016
I was about to write a comment, but when I saw the usual lunatic sewage here, I didn't.

I really don't see why PhysOrg puts up with all this crap. It drives away the people this is meant for.

Maybe the moderator is a closet anti-scientist. Go figure.

-- And yes, I can "adjust the slider" to 4 or 4.5, but then every other comment is an answer to some invisible lunatic, instead of discussing the article.
gkam
1.6 / 5 (13) Apr 15, 2016
gwrede, my own comments here from experience was met with screams of "LIAR!" and other offensive nonsense.

The vandals on his forum have ruined it, chasing everybody else away with their crude attacks. and hateful games.
yep
1.6 / 5 (7) Apr 16, 2016
Confirmation bias makes wise men fools.
Scv your post is ironic.
Andrew Palfreyman
3.4 / 5 (10) Apr 16, 2016
The moron troll density here is insufferably high. Mr. Moderator, bloody do something about it please.
cantdrive85
1 / 5 (10) Apr 17, 2016
Jupiter's moon Europa is under a constant gravitational assault. As it orbits, Europa's icy surface heaves and falls with the pull of Jupiter's gravity, creating enough heat, scientists think,

This guess has been falsified, of course they have no intention of changing the narrative.
http://www.nasa.g...ced.html
gkam
2.1 / 5 (14) Apr 17, 2016
Can't, I read your reference, and it does NOT say what you assert. It says:

"Tidal heating is also thought to be responsible for oceans of liquid water likely to exist beneath the icy crusts of Europa and Saturn's moon Enceladus."

It contradicts your assertion.
cantdrive85
1.4 / 5 (10) Apr 17, 2016
Can't, I read your reference, and it does NOT say what you assert. It says:

It contradicts your assertion.

No, not really at all as it falsifies the tidal heating model quite clearly. The first paragraph;
"Jupiter's moon Io is the most volcanically active world in the Solar System, with hundreds of volcanoes, some erupting lava fountains up to 250 miles high. However, concentrations of volcanic activity are significantly displaced from where they are expected to be based on models that predict how the moon's interior is heated, according to NASA and European Space Agency researchers."
They expound,
"We performed the first rigorous statistical analysis of the distribution of volcanoes in the new global geologic map of Io," says Hamilton. "We found a systematic eastward offset between observed and predicted volcano locations that can't be reconciled with any existing solid body tidal heating models."
"Can't be reconciled" is science speak for falsification.
cantdrive85
1.4 / 5 (11) Apr 17, 2016
Can't, I read your reference, and it does NOT say what you assert. It says:

"Tidal heating is also thought to be responsible for oceans of liquid water likely to exist beneath the icy crusts of Europa and Saturn's moon Enceladus."

It contradicts your assertion.

As I said, in spite of the obvious falsification, they have no intention of changing their narrative. It is they who are contradicting the evidence in order to cling to their failed guesses and fanciful reasonings.
gkam
2.1 / 5 (15) Apr 17, 2016
You are confusing Io with Enceladus!!

They do not even orbit the same planet!

cantdrive85
1.7 / 5 (12) Apr 17, 2016
You are confusing Io with Enceladus!!

They do not even orbit the same planet!

No, I'm quite aware that Io orbits Jupiter, Enceladus Saturn. The Io findings are a test for the tidal heating guess, and it failed miserably. Try to keep up.
torbjorn_b_g_larsson
4.7 / 5 (13) Apr 17, 2016
Of course the trolls misrepresent the article evidence as not in evidence. Oy vey!
TheGhostofOtto1923
3.9 / 5 (15) Apr 17, 2016
And yes, I can "adjust the slider" to 4 or 4.5, but then every other comment is an answer to some invisible lunatic, instead of discussing the article
gwrede, my own comments here from experience was met with screams of "LIAR!" and other offensive nonsense.

The vandals on his forum have ruined it, chasing everybody else away with their crude attacks. and hateful games
Ahahaahaaaaa george you do realize that you're the 'invisible lunatic' he's referring to?

What a moron you are.
gkam
1 / 5 (9) Apr 17, 2016
It is "Mirror Time" for otto!
Bodeplot
1.8 / 5 (10) Apr 18, 2016
Hello. I'm an electronics technician for some 20 years and new comer to this forum. I read this article and have a question. Quartz Crystal produces electricity when compressed and decompressed (and visa versa). Does water ice honour this
Piezoelectric effect under the volume scales of a planet ?. If so, how much current would be generated in the area indicated in the article ?
Mike_Massen
2 / 5 (12) Apr 19, 2016
Bodeplot Interesting query
... Quartz Crystal produces electricity when compressed and decompressed (and visa versa). Does water ice honour this
Piezoelectric effect under the volume scales of a planet ?
As it happens been reading:-
"Proton_Conduction_in_Water_Ices_Under_Electric_Field" by Giuseppe Cassone,
Paolo V. Giaquinta, Franz Saija and A. Marco Saitta

Suggests 'free' protons generated by piezo effect result in greater ionic dissociation & recombine ie Typical 2H2O -> OH- + H3O+ & variations thereof at femtosecond rate, implication is just produces heat minus a gross current vector.

Another paper I've yet to locate broadly suggests under appropriate magnetic field resulting charge separation may lengthen ionic clustering & stability thus allow a current vector but, haven't seen details yet.

Not sure how to calc current yet, strongly influenced by ice cluster variance - many long lasting & complex, other papers by same authors though :-)
Bodeplot
2.2 / 5 (10) Apr 19, 2016
Thanks for the reply Mike. The thought jumped out as I was reading this article. I can't access Giuseppe Cassone's article, but is the abstract in his/her study in regard to static electric fields ?
Mike_Massen
1.8 / 5 (10) Apr 19, 2016
Bodeplot asks
.. thought jumped out as I was reading this article. I can't access Giuseppe Cassone's article, but is the abstract in his/her study in regard to static electric fields ?
He's added to both, I have more due:-

Ab_Initio_Molecular_Dynamics_Study_of_Dissociation_of_Water_under_an_Electric_Field (5p)
&
Proton_Conduction_in_Water_Ices_Under_Electric_Field (6p)

Latter static fields yes. Can email <700KB technical which I enjoy detail or instead check link here referred to them & more general
http://www1.lsbu....nce.html
see Quick Links top left, wealth of useful data

Anyway welcome, please don't be discouraged by the robotic impotent voting patterns of d..ks challenged on unsupportable claims, they're angry redneck/bogans with huge chips on their shoulders that only drawing attention to themselves failing to notice votes useless from mindless clone id's, Lol, they take an interest, maybe worry if they don't ever ;-)
Mike_Massen
1.4 / 5 (9) Apr 19, 2016
@Bodeplot
Part abstract of 2nd paper, 1000 ch post limit
".. study of the effects
produced by a static electric field on proton conduction in ordinary
hexagonal ice (phase Ih) and in its proton-ordered counterpart (phase
XI). We performed ab initio molecular dynamics simulations of both
phases and investigated the effects produced by the field on the structure
of the material, with particular attention paid to the phenomenon of
proton transfer. We observed that in ice Ih molecules start to dissociate
for field intensities around 0.25 V/Å, as in liquid water, whereas fields
stronger than 0.36 V/Å are needed to induce a permanent proton flow.
In contrast, in ice XI, electric fields as intense as 0.22 V/Å are already
able to induce and sustain, through correlated proton jumps, an ionic
current; this behavior suggests, somewhat counterintuitively, that the
ordering of protons favors the autoprotolysis phenomenon. However,
the same is not true for static conductivities "
Bodeplot
1 / 5 (6) Apr 20, 2016
Hi Mike. Interesting research, but I was thinking more along the lines of a crystal structure resonating. With say a Quartz crystal (or any piezoelectric material), if you stress it (with sound, or a shock), it will produce a voltage, but then that self induced voltage will then produce stress in the crystal, which will then produce a voltage, then a stress, then a voltage etc.. and hence resonation will occur. This effect is used in digital electronics (ie: clock crystals that drive CPU's, Surface Acoustic Wave filters etc). I was wondering if a regional ice structure on Europa (like in the unset picture of this article) was shocked from a sudden fracture/crack (without knowing the speed of this fracture), would we observe resonation ?, and what sort of (RF?) power would we see. I was wondering if any researchers in this field reading could comment on this ?. Has any researcher thought of this effect before ?

Cheers J
Mike_Massen
1 / 5 (7) Apr 21, 2016
Bodeplot asked
.. but I was thinking more along the lines of a crystal structure resonating ..
Yes understand cyclic stress-voltage etc but, subject to many losses thus not self-sustaining. btw: I'm EE 1982, Perth, Western Australian Institute of Technology so fully appreciate your view & your nick too :-) but, wasn't into RF much then, now wifi instrumentation across cross-discipline all Eng variants & Food science

From London South Bank link, re ice, there are many structures with mixes of regularity & chaotic interfaces, constantly on move too. Key physics, systems tend to lowest energy so if you had (momentarily) pertinent structure that might offer a potential difference likely wouldn't last long as potential discharges & upsets structure returning to lowest state. Any new (primarily random) geologic activity offering more cycles goes through same tendency - I expect entropy wins long term & many ways

Structurally sound ;-) silica & metal salts likely

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