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A comment on Scientists discover evidence for a habitable region on Saturn’s moon Enceladus.

Re:Scientists discover evidence for a habitable region on Sa... by Animats on Tuesday May 16, 2017 @03:52AM (#14348037)
So there's this big hydrogen vent in a moon of Saturn. Where's the energy coming from to drive that? Too far from the sun. Enceladus is tidally locked to Saturn, so there are no tidal forces. Enceladus has very low orbital eccentricity, a near-circular orbit, so there are very low tidal forces from that. Some phenomenon must provide energy for the hydrogen jet.
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Re:Scientists discover evidence for a habitable region on Sa... by huhtenberg on Tuesday May 16, 2017 @06:00AM (#14348480)
There _are_ tidal forces. It's just that they alone don't explain the amount of heat measured by Cassini.

https://en.wikipedia.org/wiki/Enceladus#Tidal_heating

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Re:Scientists discover evidence for a habitable region on Sa... by wiredfool on Tuesday May 16, 2017 @05:25AM (#14348361)
It appears to be tidal: http://www.blastr.com/2017-5-8/no-we-havent-found-signs-life...

(link to bad astronomy, a reasonably good explainer type source)

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Re:Scientists discover evidence for a habitable region on Sa... by mcv on Tuesday May 16, 2017 @04:41AM (#14348209)
How long has it been tidally locked? Maybe the core is still hot. Or maybe other moons pass close enough to exert enough tidal forces to keep it warm.
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Re:Scientists discover evidence for a habitable region on Sa... by njarboe on Tuesday May 16, 2017 @01:42PM (#14351595)
Similar to the Earth, it would be a combination of heat from radioactive decay and the original heat of accretion slowly radiating away.
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Re:Scientists discover evidence for a habitable region on Sa... by scallycat on Tuesday May 16, 2017 @05:11AM (#14348325)
Orbital eccentricity gives rise to tidal forces in this case.
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Re:Scientists discover evidence for a habitable region on Sa... by Animats on Tuesday May 16, 2017 @02:28PM (#14352041)
What orbital eccentricity? That moon has a nearly circular orbit. Much less orbital eccentricity than Luna.
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Re:Scientists discover evidence for a habitable region on Sa... by foota on Tuesday May 16, 2017 @04:38AM (#14348197)
Couldn't it just be pressurised hydrogen?
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Re:Scientists discover evidence for a habitable region on Sa... by throwanem on Tuesday May 16, 2017 @06:46AM (#14348623)
Pressurized by what, though?
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Re:Scientists discover evidence for a habitable region on Sa... by kijin on Tuesday May 16, 2017 @08:18AM (#14348952)
The weight of all the water and ice on top of it, maybe?
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Re:Scientists discover evidence for a habitable region on Sa... by Cthulhu_ on Tuesday May 16, 2017 @06:59AM (#14348677)
Aliens.
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