Jupiter's ocean moons raise tides on each other

My observation. 116 years of observations since 1891 show Io has moved towards Jupiter by 55 km while Europa moved outward by 125 km and Ganymede moved outward by 365 km from Jupiter. The Laplace resonance in their orbits today is breaking. Io mean distance from Jupiter is 350,200 km. At the present rate of movement toward Jupiter since 1891, it would fall into Jupiter in < 1E+6 years. As the S&T report on chaos in the solar system indicated, it came as a surprise to astronomers that the Laplace resonance of the Jovian moons is slowing breaking.

ref - Hanging in the Balance, Sky & Telescope 119(4):30-31, 2010, April 2010 issue.
 
If Jupiter rotates 4x or so faster than Io orbits, the tidal action should move Io outward, right? It would be the dominant force in an in or out radial movement. So what am I missing?
 
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Helio, you said in post #3, "So what am I missing?"

My information cited a specific source from the April 2010 issue of Sky & Telescope. Other sources know this too about the Galilean moons.

"Tidal dissipation within Io and Jupiter leads to a migration of the Galilean satellites. In fact, the resonant interaction between Io, Europa and Ganymede spreads the dissipative effects from Io to the orbits of the other moons. The amount of the loss of energy and the consequent rate of the orbital evolution was determined in (Lainey et al., 2009), along with the dissipative parameters k2 / Q of Io and Jupiter...", Chaotic orbit determination in the context of the JUICE mission, https://ui.adsabs.harvard.edu/abs/2019P&SS..17604679L/abstract, October 2019
 
Helio, I had to fact-check this statement here :) "If Jupiter rotates 4x or so faster than Io orbits" MS BING shows Jupiter rotates about 12.6 km/s, Io orbits Jupiter at about 17 km/s.
But it is the difference in Jupiter's rotation period compared to Io's orbital period. Jupiter rotates in just under 10 hours, and Io takes 42.5 hours to make one orbit. So if we were on Io, we would see Jupiter spin around 4 x before we got back to where we started.

Thus, the tidal action from a faster spinning host will cause the moon to migrate outward, as does our own Moon.

Here's a paper about Io's outward motion.
 
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Helio, if you have the sources to show your are correct, then Sky & Telescope should publish a correction to Io migrating and the other Galilean moons changing at Jupiter too. I can only point to the sources I referred to and the 116 years of documented observations of Io and its distance change at Jupiter.
 
During the formation period of the moons, they migrated inward as there was balance between the outward from of gas and dust from Jupiter's equatorial region ( but flow inward at the polar regions) and gravity. Io would have formed first and produced gravity waves, of some kind, that contributed to inward migration of the sister moons to the point of their mutual resonance. The Sun removed the gas and dust too soon for Callisto to migrate inward enough, apparently.
 
Helio, if you have the sources to show your are correct, then Sky & Telescope should publish a correction to Io migrating and the other Galilean moons changing at Jupiter too. I can only point to the sources I referred to and the 116 years of documented observations of Io and its distance change at Jupiter.
I hit the wrong button when I was trying to add that link. But the paper is there now.

Also, your link doesn't work for me.
 
116 years of observations since 1891 show Io has moved towards Jupiter by 55 km while Europa moved outward by 125 km and Ganymede moved outward by 365 km from Jupiter. The Laplace resonance in their orbits today is breaking.

This is the issue, not what the Galilean moons were extrapolated to be doing 4.5 billion years ago, but what they are observed doing today in the solar system. We see apparent young age now at the moons, just like an apparent young age for the ring system of Saturn, etc. I can go on and on here :)
 
Helio, your post #8 has nothing to do with the observed changes of the Galilean moons, now tracked and documented for the past 116 years at Jupiter, starting in 1891 as Sky & Telescope reported.
Post 8 was just to mention that there was inward migration during the formation period. Post 6 gives a link that mentions "migration" of the moons 100x.
 
116 years of observations since 1891 show Io has moved towards Jupiter by 55 km while Europa moved outward by 125 km and Ganymede moved outward by 365 km from Jupiter. The Laplace resonance in their orbits today is breaking.

This is the issue, not what the Galilean moons were extrapolated to be doing 4.5 billion years ago, but what they are observed doing today in the solar system. We see apparent young age now at the moons, just like an apparent young age for the ring system of Saturn, etc. I can go on and on here :)
Please check your link. I'm happy to review it if I can read it. The link I gave shows present migration outward, apparently (I didn't read it all).
 
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Helio, this source supports the April 2010 S&T report as well as others. Io is moving inwards now towards Jupiter, not expanding away from the gas giant.

Strong tidal dissipation in Io and Jupiter from astrometric observations, https://ui.adsabs.harvard.edu/abs/2009Natur.459..957L/abstract, June 2009

Abstract "...The measured secular accelerations indicate that Io is evolving inwards, towards Jupiter, and that the three innermost Galilean moons (Io, Europa and Ganymede) are evolving out of the exact Laplace resonance."

Someone is reporting misconceptions perhaps :)
 
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Helio, this source supports the April 2010 S&T report as well as others. Io is moving inwards now towards Jupiter, not expanding away from the gas giant.

Strong tidal dissipation in Io and Jupiter from astrometric observations, https://ui.adsabs.harvard.edu/abs/2009Natur.459..957L/abstract, June 2009

Abstract "...The measured secular accelerations indicate that Io is evolving inwards, towards Jupiter, and that the three innermost Galilean moons (Io, Europa and Ganymede) are evolving out of the exact Laplace resonance."

Someone is reporting misconceptions perhaps :)
Ah, that helps, thanks! That's interesting. There is a tug-of-war, apparently, between the normal tidal forces that would cause Io and the others to migrate outward and an energy loss for Jupiter that has the opposite effect. This seems to be what the abstract says. But I can only read the abstract, not the paper.

So now I'm curious about what energy is being lost on Jupiter that counters outward migration? There is incredible amperage flow from Jupiter and Io, huge tidal forces, radiation, etc. that must be considered, apparently.

It's interesting that both links you give are much earlier than the 2016 paper showing outward movement. This is odd. :)
 
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Helio, the 2016 paper does not deny Io is moving inwards to Jupiter. "4.2 Jupiter, Figure 3 shows the predicted and measured (Lainey et al. 2009) values of Q and ttide for the moons of Jupiter. We have again used tα = 50 Gyr, although the appropriate value of tα could be different for Jupiter. The measured ttide for Io was negative, with the interpretation that the instantaneous migration of Io is inward due to eccentricity damping. This
point does not appear on the plot, and likely does not represent tidal dissipation in Jupiter caused by Europa to be quite large, Q >= 10^4, although we expect Europa to be migrating outward at ttide ∼ 20 Gyr due to its MMR with Io."


"Finally, resonance locking resolves the problems arising from current-day migration/heating rates, which imply that some moons formed long after their planets if the tidal Q is constant."

Helio, this is the real problem here at Jupiter and Saturn, similar to our Moon's tidal dissipation rate. You cannot have young moon ages at Jupiter and Saturn if the solar system is 4.5 billion years old.
 

"Finally, resonance locking resolves the problems arising from current-day migration/heating rates, which imply that some moons formed long after their planets if the tidal Q is constant."

Helio, this is the real problem here at Jupiter and Saturn, similar to our Moon's tidal dissipation rate. You cannot have young moon ages at Jupiter and Saturn if the solar system is 4.5 billion years old.
[my bold] The "if" is important because they discuss how Q is not constant.

Are you suggesting the moons are young? The paper talks about their age as that of the 4.5G yr. solar system.
 
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Yes Helio. Certainly the 116 years of telescope observations starting in 1891 as reported in Sky & Telescope of the migrations of the Galilean moons could be interpreted like this. Models developed to show their long age integration in their present orbits contain many assumptions. Example.

"Other works suggest that the Laplace resonance settled during the formation of the Galilean satellites. Greenberg (1982) conjectured that the satellites were originally in deep resonance and that they are currently evolving out of resonance. In this scenario, the forced eccentricities of the satellites were initially much higher, with a consequent stronger tidal friction within all three resonant moons. Greenberg (1987) found a path of stable configurations leading from the current configuration of the Laplace resonance back to deeper resonant states. Forced to follow this path because of tidal dissipation, the Laplace angle would then have passed through asymmetric equilibria (i.e., different from 0 or π). Nevertheless, this scenario gives no information about how primordial the Laplace resonance is. According to Peale & Lee (2002), the Laplace resonance could have settled during the formation of the satellites in the circumjovian disk as a result of differential migration. Following the scenario depicted by Canup & Ward (2002), Ganymede underwent the faster Type I migration because of its larger mass. Moving toward Jupiter, it first captured Europa in resonance, followed by Io, and this process happened relatively quickly (about 10^5 years). After the dissipation of the disk, the satellites then reached their current state by tidal dissipation.", https://arxiv.org/pdf/2001.01106.pdf

"ABSTRACT Context. The Galilean satellites have very complex orbital dynamics due to the mean-motion resonances and the tidal forces acting in the system. The strong dissipation in the couple Jupiter–Io is spread to all the moons involved in the so-called Laplace resonance (Io, Europa, and Ganymede), leading to a migration of their orbits. Aims. We aim to characterize the future behavior of the Galilean satellites over the Solar System lifetime and to quantify the stability of the Laplace resonance. Tidal dissipation permits the satellites to exit from the current resonances or be captured into new ones, causing large variation in the moons’ orbital elements. In particular, we want to investigate the possible capture of Callisto into resonance. Methods. We performed hundreds of propagations using an improved version of a recent semi-analytical model."

Jupiter's Galilean moons like Earth's Moon has tidal dissipation rate issues. if there is no giant impact model for the Moon, the current tidal dissipation rate shows the Moon kissing the Earth only 1.5 billion years ago. Io has been studied extensively since 1891 in these reports. As the arxiv link states "In the case of the couple Jupiter–Io, the most reliable estimate of the dissipative parameters was obtained by Lainey et al. (2009), who fitted a complete numerical model to astrometric observations taken from 1891 to 2007. The orbit determination revealed a strong energy dissipation within Io and Jupiter..."

So young Galilean moons like young Saturn ring age - looks like recent catastrophism in the solar system :)
 
Yes Helio. Certainly the 116 years of telescope observations starting in 1891 as reported in Sky & Telescope of the migrations of the Galilean moons could be interpreted like this. Models developed to show their long age integration in their present orbits contain many assumptions.
Yes, all science (and engineering) require initial conditions. Assumptions are suppositions and they are typically what comes prior to conjectures, then hypotheses, then if they are overarching in scope, theories.

What helps weed out the bad assumptions is having multiple lines of evidence. So an assumption or assumptions can bring forth a scientific model if it has objective evidence giving it weight.

The most popular model, I think, for the moons of Jupiter can be summarized (I hope :)):

1) Jupiter was in a very dense part of the early solar accretion disk. The fact that it was just outside the snowline means it had all those ices to build from.
2) The moons formed at the same time in this very dense gas and dust accretion region, especially as the accretion disk for Jupiter formed.
3) The gas and dust, being very small, had slower rates in the orbit around Jupiter, similar to that of the solar disk.
4) As clumps formed into large objects (moons) they lost a lot of their orbital suspension and began to spiral inward toward Jupiter.
5) As long as the disk was still around, these newly formed moons augured into Jupiter.
6) The EM dynamics of Jupiter's core created a hole, or void, region around itself.
7) Io, in its inward spiral, was the first to benefit from the void and it settled into orbit, though it would then begin to migrate outwarrd due to tidal action.
8) Europa was still spiraling inward but fell into resonance with Io.
9) Ganymede did the same with Europa, along with resonance assistance from Io.
10) Callisto came "late to the party" and the gas and dust were dissipated to the point where it didn't reach a resonance orbit with the others.
11) The resonance dampened the formation of circular orbits, thus eccentricity exists.
12) The eccentricity increase the heating, so temperatures of, say, Europa are high enough to have a huge briny ocean. [The less briny water is less dense, which rises and freezes forming an ice cap.]
13) Jupiter's tidal action, caused by its fast rotation rate, drags Io along in its orbit causing it to speed up, thus causing it to migrate outward.
14) The rate of movement is dampened since it must also drag the other two sisters along due to the resonance, though they too are pushed forward by tidal actions, but the force is an inverse cube law so distance makes a big difference.

I doubt you will find many who will claim Io is now spiraling inward, It's plausible that circumstances over eons have affected that resonance in accord with the paper you cite, but show my a paper that predicts Io will crash burn. That would be interesting to see but seems, IMO, to be an ATM point of view.

Example.

Following the scenario depicted by Canup & Ward (2002), Ganymede underwent the faster Type I migration because of its larger mass. Moving toward Jupiter, it first captured Europa in resonance, followed by Io, and this process happened relatively quickly (about 10^5 years). After the dissipation of the disk, the satellites then reached their current state by tidal dissipation.",
Ok, notice that this is another model in how they got into resonance. But I like the one above, which comes from Erik Asphaug (Planetary Science, U of Arizona)

Neither model is arguing that Io will auger in, or am I wrong?

"ABSTRACT Context. The Galilean satellites have very complex orbital dynamics due to the mean-motion resonances and the tidal forces acting in the system.
Yes, this gets more into your point about assumptions. The problem, I think, for calculation tidal forces is to fully understand all the numerous structural variables of the spinning host. If you start with a perfectly spherical planet made of perfectly rigid material, say less flexible than diamond, then the tidal action will be nothing, at least I think this is correct.

The flexing of the surface and subsurface layers, the variations in density by both latitude and longitude, the sloshing effects of resonant things like bays (eg Bay of Funday), the regional flows, etc. all contribute to the amount of tidal action on the moon. Then all these variables must be applied to the moon as well, as well as, the orbital resonance effects.

The more we learn about Jupiter's interior the more we will be able to apply retrodictive science to the moons of Jupiter.

There are stories out now about the discovery that Titan's migration (outward) is perhaps 10x what they held it to be, though others had predicted it would be greater. The complexity of Saturn's internal structure, including its atmospheric flows, is mostly the challenge to all the assumptions in the earlier model.

Jupiter's Galilean moons like Earth's Moon has tidal dissipation rate issues. if there is no giant impact model for the Moon, the current tidal dissipation rate shows the Moon kissing the Earth only 1.5 billion years ago.
Nope. Given all the variables, the migration rate of the Moon is a very crude way to give the Moon any age, only a minimum. If you divide its distance by its annual migration rate outward, 3.8 cm/yr., it gives the Moon a 10 billion year history. But, another variable is that inverse cube law for tidal action, so when the Moon was much closer, it would have been migrating at a much faster rate. All one needs to know are those thousands of density variations, sloshing resonances, etc. to calculate the age based on the refined equations.

Fortunately, as mentioned at the beginning, we have multiple lines of independent evidence to do a better job on determining the Moon's age. The craters of the Moon are such that they argue for the Moon being around for the Heavy Bombardment period long ago, so it has to be at least that old. Also, the samples from Apollo also demonstrate an even greater age. There are probably other lines of evidence as well.

So young Galilean moons like young Saturn ring age - looks like recent catastrophism in the solar system :)
No, they are stating that the resonant stability will be for 1.5 Gyrs. I didn't search hard -- though the word "age" isn't in that paper -- that would indicate they suggest the moons are young.
 
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Helio, your post #20, may present some misconceptions :) The tidal dissipation rate for the Moon shows an orbital history only about 1.5 Gyr, reference - Explicitly modelled deep-time tidal dissipation and its implication for Lunar history, https://ui.adsabs.harvard.edu/abs/2017E&PSL.461...46G/abstract, March 2017. "Dissipation of tidal energy causes the Moon to recede from the Earth. The currently measured rate of recession implies that the age of the Lunar orbit is 1500 My old, but the Moon is known to be 4500 My old. Consequently, it has been proposed that tidal energy dissipation was weaker in the Earth's past, but explicit numerical calculations are missing for such long time intervals. Here, for the first time, numerical tidal model simulations linked to climate model output are conducted for a range of paleogeographic configurations over the last 252 My..."

The 1.5 billion year period and tidal dissipation rate problem is referenced in other reports too. Reference - Thank the moon for Earth's lengthening day, https://www.sciencedaily.com/releases/2018/06/180604151200.htm, June 2018 "...For instance, the moon is currently moving away from Earth at a rate of 3.82 centimeters per year. Using this present day rate, scientists extrapolating back through time calculated that "beyond about 1.5 billion years ago, the moon would have been close enough that its gravitational interactions with the Earth would have ripped the moon apart," Meyers explains. Yet, we know the moon is 4.5 billion years old."

This is a long standing problem with the tidal dissipation rate parameter for the receding Moon and the angular momentum of the Earth-Moon system. The giant impact model was developed to help solve tidal dissipation rate(s) problems and the angular momentum problem of the Earth-Moon system as well as provide an explanation for the origin of the Moon that fits with the 4.5 billion years old date. In the giant impact model, the proto-Moon forms near the Earth's Roche limit or about 3 earth radii distance. Today the Moon orbits near 60.3 earth radii distance. Rapid expansion of the early Moon's orbit is required in the giant impact model and then that rapid expansion and tidal dissipation slows down.

Helio, you mentioned "There are stories out now about the discovery that Titan's migration (outward) is perhaps 10x what they held it to be, though others had predicted it would be greater. "

I note this about Titan's present orbit at Saturn. ""...Now, decades of measurements and calculations have revealed that Titan's orbit around Saturn is expanding—meaning, the moon is getting farther and farther away from the planet—at a rate about 100 times faster than expected. The research suggests that Titan was born much closer to Saturn and migrated out to its current distance of 1.2 million kilometers (about 746,000 miles) over 4.5 billion years...", reference - Titan is migrating away from Saturn 100 times faster than previously predicted, https://phys.org/news/2020-06-titan-migrating-saturn-faster-previously.html, June 2020.

Helio, you said "I doubt you will find many who will claim Io is now spiraling inward, It's plausible that circumstances over eons have affected that resonance in accord with the paper you cite, but show my a paper that predicts Io will crash burn. That would be interesting to see but seems, IMO, to be an ATM point of view."

My post #2 cited the April 2010 Sky & Telescope report and this does show that observations using 116 years of data for Io since 1891 show the moon has migrated closer to Jupiter by 55 km. This does not claim that Io will crash and burn at Jupiter but does show interesting issues with tidal forces and long age calculations for the moon as well as other moons in the solar system. That is my main point. Apollo lunar samples dated via radiometric methods also come with very young, CRE ages, just like all meteorites. Short lifetimes of comets need an Oort Cloud, short orbital lifetimes of asteroids, some like Centaurs need age dating reconciliations, surfaces with young age calculations or crater counts. Remember this is the iron clad age for the solar system reported as about 4.6 billion years old. References, The age of the Solar System redefined by the oldest Pb-Pb age of a meteoritic inclusion, https://ui.adsabs.harvard.edu/abs/2010NatGe...3..637B/abstract, September 2010.

Age of meteorites and the earth, https://ui.adsabs.harvard.edu/abs/1956GeCoA..10..230P/abstract, October 1956. My note, Clair Patterson meteorite age paradigm fixes the age of the Earth.

In the solar system, when objects are found that indicate or suggest much younger ages than the paradigm established in 1956 and used ever since, science needs various reconciliation calculations and methods to make everything fit nicely. The space.com report discussed tides and tidal forces (gravity) in the Galilean moons, I decided to expand the thinking a bit here :) Good discussion Helio---Rod
 
rod,

If you can be more explicit with where you are going, then I can better offer what little I know.

Helio, your post #20, may present some misconceptions :) The tidal dissipation rate for the Moon shows an orbital history only about 1.5 Gyr, reference - Explicitly modelled deep-time tidal dissipation and its implication for Lunar history,...
So do you mean to present that the Moon's current orbital stability has been essentially the same for 1.5G yrs, or that the Moon might only be 1.5 Gyrs old? I'm curious what you think these articles are saying.

The currently measured rate of recession implies that the age of the Lunar orbit is 1500 My old,...
[and]..."...For instance, the moon is currently moving away from Earth at a rate of 3.82 centimeters per year. Using this present day rate, scientists extrapolating back through time calculated that "beyond about 1.5 billion years ago
Well, not really. The Moon is 38 billion centimeters away, and it is migrating outward at 3.8 cm per year, which in this oversimplistic way demonstrates an age up to 10 Gyrs. So the other details need to be inserted to argue for a 1.5Gyr view, or even the 4.5 G yr. view. That is why I listed some of the relative variables above.

In the giant impact model, the proto-Moon forms near the Earth's Roche limit or about 3 earth radii distance. Today the Moon orbits near 60.3 earth radii distance. Rapid expansion of the early Moon's orbit is required in the giant impact model and then that rapid expansion and tidal dissipation slows down.
But rapid expansion (migration) of the early Moon isn't just a guess it's in accord with the laws of physics. The inverse cube law for tidal action isn't in question, so the close proximity of the Moon would have produced a very rapid migration rate compared to today's rate.

... The research suggests that Titan was born much closer to Saturn and migrated out to its current distance of 1.2 million kilometers (about 746,000 miles) over 4.5 billion years...", reference - Titan is migrating away from Saturn 100 times faster than previously predicted, https://phys.org/news/2020-06-titan-migrating-saturn-faster-previously.html, June 2020.
Ok, 100x, but the result still suggests a formation period of 4.5 G yrs ago.

...This does not claim that Io will crash and burn at Jupiter but does show interesting issues with tidal forces and long age calculations for the moon as well as other moons in the solar system. That is my main point. [Apollo lunar samples dated via radiometric methods also come with very young, CRE ages, just like all meteorites.
The tweaking of moon migrations around Saturn are expected as structural information for Saturn itself is discovered. The Earth is far better understood.


Short lifetimes of comets need an Oort Cloud, short orbital lifetimes of asteroids, some like Centaurs need age dating reconciliations, surfaces with young age calculations or crater counts. Remember this is the iron clad age for the solar system reported as about 4.6 billion years old. References, The age of the Solar System redefined by the oldest Pb-Pb age of a meteoritic inclusion, https://ui.adsabs.harvard.edu/abs/2010NatGe...3..637B/abstract, September 2010.
"Iron clad" is never taken to be an absolute. Those same scientist likely would have been quick to suggest further tweaking is likely but that the 4.6 Gyr was demonstrably close.

Age of meteorites and the earth, https://ui.adsabs.harvard.edu/abs/1956GeCoA..10..230P/abstract, October 1956. My note, Clair Patterson meteorite age paradigm fixes the age of the Earth.
Right, and the more we study material from the earliest periods of formation, the better the ~ 4.6 G yr age becomes tweaked. BTW, even studies with CAI material is not ideal for the earliest age as these likely formed just after the first material, IIRC.
 
This is one more piece of evidence supporting a relatively-recent, 650 Ma, massive, high-angular-momentum debris disk in our highly-unusual solar system:
- Anomalously warm moons of Jupiter
- Marinoan glaciation on Snowball Earth
- Low large-crater count on Ceres, with an internal ocean, in a minor planet with NO tidal heating
- Cold classical KBOs, on low-inclination, low-eccentricity orbits, composed of similar-size and similar-color binary systems, in quiescent (unperturbed) orbits, formed in situ by streaming instability
- Geologically-active surface of Pluto, in a synchronous orbit with Charon, with NO tidal heating

This is extraordinary evidence for an extraordinary claim in a highly-unusual solar system that REQUIRES an extraordinary explanation
 

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