Pluto System Speculation |
Pluto System Speculation |
Jan 15 2016, 03:17 PM
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#121
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Senior Member Group: Members Posts: 2997 Joined: 30-October 04 Member No.: 105 |
I've been examining satellite imagery of the Arctic/Antarctic and Greenland. This is probably the closest Terrestrial analogy to Sputnik Planum we have. And going further afield from strict analogy, I've also looked at the ice-sheets/lava fields of Iceland for ideas away from the Tombaugh region.
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Jan 16 2016, 02:29 PM
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#122
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
That has occurred to me, too. A clathrate couldn't dissolve and still be a clathrate. But could it weather (physically break down) into a minimum clathrate "cell" or structure? I tend to think of clathrates as being akin to silicates at these temperatures, but that is not a strict analogy since the SiO4 and H2O bonds are way different. What would clathrate nanoparticles behave like? There is some work on ice clathrates of methane CH4 and ethane C2H8 forming at geologic depths on Titan. http://spaceref.com/saturn/icy-aquifers-on...e-rainfall.html The inference from Titan is that in the icy bodies of the outer solar system, clathrates could form a thick subterranean layer. At these temperatures, really over-simplifying water ice = basaltic ocean crust volatile ices = oceans clathrates = continental crust The study about Titan and clathrates notes that clathrates are good at separating liquids with different sized molecules. For Pluto at depth, where you might have liquid methane, liquid N2 and liquid CO, that separation effect could be very interesting. Methane clathrates would be similar on Titan and Pluto, and although carbon monoxide and nitrogen are chemically different from ethane, the molecules are roughly the same size as ethane, so the cage-size based fractionation should be very similar. So, Plutonian crustal clathrates might show the fractionation effect mentioned for Titan, e.g. they might be able to separate liquid phases because of the smaller size of the CH4 molecules compared to the larger CO and N2 molecules. One result of this could be that some areas on Pluto are underlain by deep methane aquifers while other areas are underlain by aquifers of carbon monoxide and nitrogen. On Titan, the clathrates not only separate chemicals but appear to polymerize then, methane to ethane, ethane to propane. So, perhaps at depth, Pluto clathrates could catalyze methane, ethane, propane; and also carbon monoxide to polycarbonyl. Finally, if clathrates can catalyze polymerization of three CH4 molecules into propane, then perhaps starting with CH4, N2, and CO results in polymerization into red tholins? |
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Jan 16 2016, 03:12 PM
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#123
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
Would that also be the case under various other conditions? As it turns out, water ice apparently can dissolve in liquid nitrogen, but can be done only on a small scale under difficult conditions in the laboratory. Imagine how complex the interactions are in the vast scale and intricacies of Pluto's crust and mantle, not to mention all the unknowns (and unknowables). It may be centuries before we have a solid grasp of what makes Pluto tick. There's a bit of discussion about clathrates, CH4, N2 etc, in regards to Enceladus. http://www.unmannedspaceflight.com/index.p...ost&p=77810 A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume Susan W. Kieffer, Xinli Lu, Craig M. Bethke, John R. Spencer, Stephen Marshak, and Alexandra Navrotsky Science 314, 1764-1766 (2006) Abstract Supporting Online Material See also the accompanying News of the Week article "A Dry View of Enceladus Puts a Damper on Chances for Life There" by Richard Kerr. |
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Jan 16 2016, 11:36 PM
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#124
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Senior Member Group: Members Posts: 2997 Joined: 30-October 04 Member No.: 105 |
So clathrates can be considered to be the zeolites of an icy world. Strangerer and strangerer...
--Bill -------------------- |
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Jan 17 2016, 12:15 AM
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#125
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
So clathrates can be considered to be the zeolites of an icy world. Strangerer and strangerer... --Bill Well, not quite. It's not about large void spaces like zeolites, rather it's the incorporation of a "volatile" into the solid crystal structure of the "rock". On early earth, the first rocks to cool would be basalt. Basalt is the dense black rock that makes the ocean crust. When you re-melt basalt in the presence with water, (e.g. run basalt through a subduction zone) the water is incorporated into the mix and you get granite, the less-dense light colored rock that makes the continental crust. So, on outer planets, "pure" H2O ices would be analogous to "basalt", while the H2O clathrates would be analogous to granites as rock that has incorporated a volatile into the crystal structure. |
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Jan 18 2016, 03:10 PM
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#126
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Senior Member Group: Members Posts: 2997 Joined: 30-October 04 Member No.: 105 |
That is an excellent analogy. I tend to look at terrestrial clathrates, with the methane clathrate or methane hydrate being a type example, as a magical, mystical substance that binds up methane and therefore is akin to a zeolite. The classical description is a "cage structure enclosing methane molecules" and so on. Fairly simplistic.
I need to go do some reading... --Bill -------------------- |
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Feb 4 2016, 11:03 PM
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#127
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Senior Member Group: Members Posts: 2997 Joined: 30-October 04 Member No.: 105 |
astounding.. i hadnt noticed the three curious conical features before (see excerpt below), the opposite shadowing from surrounding terrain suggests they are depressions. [attachment=38876:sinx.png] Early Lunar studies suggested that "conical" craters are the product of either volcanic (or gas) vents or of the sapping (or draining) of fine dust into a subsurface cavity. Given that these craters occur on a water-rocky terrain on could speculate that they are gas vents. --Bill -------------------- |
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Feb 10 2016, 09:30 PM
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#128
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Junior Member Group: Members Posts: 98 Joined: 30-November 05 From: Antibes, France Member No.: 594 |
Excellent and captivating presentation (at Drexel University) by Alan Stern that I've just followed on youtube:
https://www.youtube.com/watch?v=mIfqjbCNO3s Regarding the famous "snakeskin" terrain, he says the composition involves methane ice. The pseudo-stalagmites may be composed of methane ice... He says there are sinuous channels which may be related to ancien flows of liquid nitrogen at a time when the atmosphere was heavier, denser. He postulates the presumed convection process associated with the polygons of Sputnik Planum may be related to an internal heat source from the progressive freezing of a water ocean beneath the icy crust. The heat is expelled upward from the freezing process... That's at least his favorite assumption at the moment. |
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Feb 12 2016, 03:50 AM
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#129
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
QUOTE ... if Pluto does have the occasional runaway green house, (or impact) it might get to 63 Kelvin with a transient one-tenth bar atmosphere and have liquid N2 for a while. And it seems like the volume of ice in sputnik is just about what you would see if that entire transient atmosphere froze out into one polar deposit. Bump. Wow. Flowing liquid nitrogen may have carved drainage channels Pluto? https://www.youtube.com/watch?v=mIfqjbCNO3s One hour, two minutes in. Noticed that a stitched black & white lorri image by wildespace shows the area with the channels http://www.unmannedspaceflight.com/index.p...st&p=227627 |
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Feb 13 2016, 03:26 PM
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#130
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Senior Member Group: Members Posts: 2997 Joined: 30-October 04 Member No.: 105 |
What wonderful worlds. Even though the temperature is low they ar not stuck in a deep-freeze.
--Bill -------------------- |
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Mar 22 2016, 02:02 PM
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#131
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
Interesting idea. You need about .1 bar of atmosphere to allow N2 to flow like a liquid on pluto. Basically, if Pluto had a transient warming event, either procession or perhaps a collision, the surface temperature would rise to 63 Kelvin, then you'd start melting N2 into atmosphere, and once you have .1 bar of N2, you could get liquid. ... Rather interesting actually - if Pluto does have the occasional runaway green house, (or impact) it might get to 63 Kelvin with a transient one-tenth bar atmosphere and have liquid N2 for a while. Bump- So Pluto is like the "Diamond Mountains of Lower Pomerania" That's the Brothers Grimm fairy tale, where a finch sharpening it's beak wears down a mountain. Instead, every 800,000 years, Pluto warms, a thin atmosphere forms which allows brooks and rivers of N2 flow for a few years. Then back to endless winter to wait almost a million years... http://phenomena.nationalgeographic.com/20...-lake-on-pluto/ QUOTE “The pressure changes radically,” says New Horizons principal investigator Alan Stern. Today, he says, Pluto’s atmospheric pressure is “atypically low,” noting that at maximum it can be more than 20,000 times the current reading.
That means surface temperatures must be fluctuating enough to mess with the nitrogen on Pluto’s surface, driving it from a frozen solid into a gas. And sometimes, the temperature and pressure occasionally rise high enough for liquid nitrogen to flow on the surface. The last time temperatures were sufficiently high to melt nitrogen was around 800,000 years ago, when Pluto’s orbital alignment led to its most extreme warm climate, says MIT’s Richard Binzel. |
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Mar 22 2016, 05:57 PM
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#132
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Senior Member Group: Members Posts: 2073 Joined: 13-February 10 From: Ontario Member No.: 5221 |
I recall that there have been findings that Mars has had extreme periods of tilt in its past, because of the lack of large satellites to prevent a wobble, but how would Pluto's axis undergo precession in such an extreme way, though? Doesn't Charon stabilize the axis just like our Moon does for Earth? Certainly intriguing...
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Mar 22 2016, 07:42 PM
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#133
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
What would be relevant are the moment of inertia of the system and the torque that is applied to the system. We can't know the internal moments of inertia of Pluto and Charon, but I would guess that the system's MOI can be estimated from externally observable quantities. There should be an answer for this, but it's a research project to get to the bottom of it.
Pluto's orbit is tightly controlled by Neptune, which says something about how much Neptune influences the Pluto-Charon system. But the answer to your question involves pages of math. |
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Mar 22 2016, 09:32 PM
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#134
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
I recall that there have been findings that Mars has had extreme periods of tilt in its past, because of the lack of large satellites to prevent a wobble, Eh, as to Mars, there was a recent paper and discussion that the weight of the Tharsis bulge actually shifted the martian equator by 20 degrees. Basically, Martian valleys/tropical rain bands and ice fields only make sense if you turn Mars by 20 degrees, then the highlands and lowlands are balanced. Pluto should be susceptible to the same crust-shifting effect, ice re-deposition causes a huge mass redistribution, which forces the outer crust to shift. Neat thing is, on Pluto, every 800,000 years, that ice could melt or sublimate, and then re-deposit somewhere else, causing ANOTHER round of crust shifting. Interesting to think of that interationc between atmosphere and planet. On Venus, it's possible that the atmosphere has actually reversed the rotation of the planet, on Pluto, it's possible that the weight of the frozen atmosphere reorients the poles every few million years. |
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Mar 22 2016, 11:03 PM
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#135
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Senior Member Group: Members Posts: 2073 Joined: 13-February 10 From: Ontario Member No.: 5221 |
But the answer to your question involves pages of math. No surprise there Thanks for the info from you both, though still odd to consider. A Plutonian equivalent of the Milankovitch cycles? The Sun is too distant to have an effect, so it must be either Neptune or internal forces. Long term observations will shed light (no pun intended)... |
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