On: Scientists discover evidence for a habitable regio...

[Animats]

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.

[huhtenberg → Animats]

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

[wiredfool → Animats]

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)

[mcv → Animats]

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.

[njarboe → Animats]

Similar to the Earth, it would be a combination of heat from radioactive decay and the original heat of accretion slowly radiating away.

[scallycat → Animats]

Orbital eccentricity gives rise to tidal forces in this case.

[Animats → scallycat]

What orbital eccentricity? That moon has a nearly circular orbit. Much less orbital eccentricity than Luna.

[foota → Animats]

Couldn't it just be pressurised hydrogen?

[throwanem → foota]

Pressurized by what, though?

[kijin → throwanem]

The weight of all the water and ice on top of it, maybe?

[Cthulhu_ → throwanem]

Aliens.