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The only mechanism that explained the data was cryovolcanism, the eruption of liquids and gases in an ultra-cold environment.

This action could be occurring on timescales as short as a few hours or days, and at levels that would recoat Charon to a depth of one millimeter every 100,000 years.
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- Charon: An Ice Machine in the Ultimate Deep Freeze

...I'm working on a story right now...type fast, Emily, type fast...

I can report now that there has been so much media interest in this that the first author on the paper, Jason Cook, had his email inbox fill up yesterday and start bouncing messages!

--Emily

Very interesting! Okay...so now I am confused. Occultation data suggests the presence of a large impact basin on Charon's leading hemisphere and now we see that there is geologic activity on this world. Maybe this moon is kinda like Dione, most an ancient surface with numerous fractures that penetrate down to some liquid water/ammonia pocket in the interior.

Hopefully, they can determine the likely longitudes for active locations. Maybe NH's trajectory can be adjusted to image these areas.

We know there are Geysers on Triton, now Charon, so I guess Pluton is on the list too...

This is annoying:



Not because of any residual quarrel about Pluto, but because nobody has ever said that objects other than planets could not have moons (we speak of "asteroid moons" easily enough) and because the phrasing "companion world" is without either warrant or precedent. What is the Gemini Observatory up to here?

From Emily's excellent article (way to fly those fingers, E, and nice job on the illustration, Doug!):

"The possibility is raised," Cook and coauthors write, "that there is more liquid water in the Kuiper belt than on Earth."

What else can be said but <clink> ?

The Pluto part was done a few weeks ago as part of something else - the Charon was just a variation on it. The texture, for those wondering, is 50% Dave Seals Charon map, 50% Enceladus - as a noise pattern mixture.

Doug

Hmm. This is interesting.

I wouldn't have thought that something as small as Charon could still have liquid water in its interior. This isn't like Enceladus or Miranda where a big gas-giant planet is available to power tidal heating.

Just to speculate: My understanding is that a lot of the Earth's uranium floated to the crustal layer during the planet's formation. You'd expect such a heavy element to sink, but uranium likes to combine chemically with oxygen, and that provides it with a lot of buoyancy.

On a body like Charon, though, the uranium would only be able to float to the top of the core -- where it would remain, insulated by a 500-km-deep layer of ice. So should we expect ice/rock bodies like Pluto, Charon and Triton to hold onto their radiothermal heat more efficiently than similarly-sized rocky bodies? (Assuming we could find any similarly sized rocky bodies, of course.)

Wow.

Would this then imply that we might expect ancient cryovolcanoes, like really old and cratered versions of Tortola facula or Ganesa macula on Titan, on the surface of larger KBO objects like Pluto and friends?

-Mike

If the surface is covered with fresh ice I can imagine the surface looking quite young...

Apart from heat due to radioactive materials, are there any other potential heat sources that far out? For example (picks an idea out of the air) could there have been a recent impact large enough to have liquified the interior? I know any ideas would be pure speculation, but thats all we'll have until june 2015 . The ammonia in the (possible) water might allow for heat sources ordinarily to feeble to be considered to have an impact. Would anyone care to speculate?

Charon - the ultimate in fresh powder skiing...or in the limited gravity with Pluto pulling so closely would it be powder surfing?

Or would it be powder cross country, with few sloped surfaces?

A current projected resurfacing rate of 1 mm/1E5 years would only give about an inch and a half of powder over the age of the solar system.

Even if the resurfacing rates were much, much higher in the past, the powder may only obscure some of the smaller really old features.

It should look quite pretty. I imagine craters and peaks all lightly coated and sparkly with a thin ice glazing.

[Littlebit, I'd strongly suggest using rental skis, instead of your own. ]

-Mike

Probably not... an impact big enough to liquify the interior would probably also have thrown Charon's orbit off-circular. We'd be able to see the ellipticity of its orbit, I think.

There is also the chromographic soil effect: At a nuclear facility near Hanford, Washington, extremely low concentration radioactive wastes were dumped in an evaporative sludge pond. Over time (probably decades), elements were chomographically separated in the clay, and a layer of high energy waste was concentrated naturally near the surface to an unnatrual level - almost self sustaining.

I also have a questionable account about how the problem was discovered: rabbits managed to get through the fence and nibble on grasses growing in the pond. Routine radioactive measurements taken outside of the fence uncovered radioactive rabbit pellets...

So THAT'S where they filmed "Night of the Lepus"!

Only if the...er...evidence was the size of rugby balls. (Still can't believe Gregory Peck ever agreed to be in that lemon...)

EDIt: I'm wrong, thank God...Peck wasn't in it...although Stuart Whitman & Janet Leigh's talents were definitely wasted, so the mourning is appropriate...

Likely nucleides for heating mantles (at least for Earth) are Uranium, Thorium, and Potassium-40.

According to Wikipedia (my copy of Cotton and Wilkenson's is back at the office), uranium likes being in oxidation states U(+4) or U(+6), with the most common form in nature (terrestrial conditions) being U3O8. "Both oxide forms are solids that have low solubility in water and are stable over a wide range of environmental conditions."

But at the bottom of an ammonia water ocean, what would be the preferred form?

Would it be a uranium hydroxide (U[OH]6), or would it be ligated to ammonium (NH4)xUy(OH)z? Could there be hot water percolating throughout a silicate core concentrating some bizarre uranium species at the silicate/water interface?

In Littlebit's Hanford scenario, the water percolates upward and evaporates. (Or does it percolate down, and concentrate the stuff at the "top of the column" - leaching away everything but the uranium)

On Charon, maybe the material percolates "upwards" but the uranium species (U3O8?) crashes out when it hits cooler water?

This just begs for a cool (and easy to do experiment with a scintillation counter) experimental model.

Just not in my lab....

-Mike

(I wonder what the forms of other likely radionucleides are? WWTD [What Would Thorium Do?])
[Potassium(40) is easy: KOH would be the preferred form and it is extremely soluble in water - it would not be able to concentrate]