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Posted by Teraen (Member # 8612) on :
So I lost my notes on the short story I am writing (Curses!) and I can't remember which moon I picked.

Does anyone know the moon (around Saturn or Jupiter, I think) that has an icy crust of ammonia and carbon dioxide?

Wikipedia is only partially useful here...

Posted by Strychnine (Member # 9207) on :
are you thinking of Europa?
Posted by RationalDelirium (Member # 9019) on :
Maybe Titan? Though that has seas of liquid methane. Not so sure about the consistency of its crust.
Posted by JSchuler (Member # 8970) on :
I'd place my money on Callisto. It actually has a (very very thin) CO2 atmosphere.
Posted by Teraen (Member # 8612) on :
See what I mean? Hard to get info. Its one of those moons that has FROZEN ammonia and carbon dioxide on it. Almost everything I can find involves atmosphere. Its frustrating to no end!
Posted by JSchuler (Member # 8970) on :
If it has frozen CO2, it will likely also have a CO2 atmosphere. Same thing as Earth, which has a lot of water vapor in its atmosphere, but still has water ice.

The thing about Callisto is its atmosphere is so thin, it wouldn't last long (and I'm not geologically speaking here) unless there was something generating it. Sublimating dry ice would do it.

As far as frozen ammonia, nearly every moon around Jupiter and Saturn has that.

Posted by Rhaythe (Member # 7857) on :
You are likely thinking of Titan. To quote Wikipedia:

Titan's watery magma would be denser than its solid icy crust. This means that cryovolcanism on Titan would require a large amount of additional energy to operate, possibly via tidal flexing from nearby Saturn. Alternatively, the pressure necessary to drive the cryovolcanoes may be caused by ice Ih "underplating" Titan's outer shell. The low-pressure ice, overlaying a liquid layer of ammonium sulfate, ascends buoyantly, and the unstable system can produce dramatic plume events. Titan is resurfaced through the process by grain-sized ice and ammonium sulfate ash, which helps produce a wind-shaped landscape and sand dune features.

Hope this helps:


Posted by JSchuler (Member # 8970) on :
Except the ammonia is liquid, and it sounds like whatever makes it to the surface reacts with sulfuric acid and becomes ammonium sulfate (which is a solid, not a liquid, and therefore not ice). Finding pure frozen ammonia on the surface of Titan sounds about as natural as finding pure iron on the surface of Earth.

Plus, Titan is such a weird duck that the flavor of shaved ice on its beaches probably wouldn't make the postcard.

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