[X] My Assistant

[SigurRosFan]

- Cosmic rays could power icy moon's plumes (New Scientist)

[Rob Pinnegar]

Hmmm, a refreshingly strange idea. I guess they should at least get brownie points for originality.

Sorry about the closed-mindedness, but I don't buy this one at all, for reasons that are outlined in the article.

[volcanopele]

Yeah, I don't quite buy it either. You still have to explain why Enceladus is gifted with geologic activity and not Mimas. The author suggests that this works on Enceladus because maybe it has Ammonia-rich slush near the surface, but then you would still need a heat source to get that...

[Rob Pinnegar]

...And then you also have to explain why Enceladus has this slush and Tethys, Dione and Rhea apparently don't (as is pointed out in the article).

I just have trouble believing that chemical reactions could provide this much energy over such a long period of time. Although a body the size of Enceladus could contain a lot of ammonia, this would have to run out sooner or later. Tidal heating is, for all intents and purposes, a "renewable" source of energy at Enceladus and just seems much more reasonable.

Having said that, this hypothesis might explain the origin of *some* of the energy that powers Enceladus' plumes. Certainly the mechanism seems like the sort of thing that could technically work -- but what percentage of the total observed energy release could it actually provide? One percent? A tenth of a percent? I don't know the subject well enough to come up with an educated guess, but it'd surprise me if it were much more than that. (Mind you, being surprised is what makes this game so much fun.)

It's worth pointing out here that Earth has more than one source of internal heat. In addition to the heat that is released by decaying uranium and thorium isotopes, there's also the latent heat that is released by the infinitesmal growth of the inner core as the liquid outer core slowly solidifies. One of those mechanisms clearly dominates the other, and, if one were to try to explain Earth's internal heat source from first principles, it would be a good idea to try to get a good solid idea of the magnitude of the dominant source before focussing too much on secondary sources. This is where we are with Enceladus right now.

I guess it wouldn't hurt to speculate about secondary sources -- however, it's difficult to think of the mass media as being the forum of choice for that sort of thing.

[Edit: After writing the above post, I did a bit of looking around for information on latent heat release by the inner core, and discovered one of the best crackpot theories I've seen in a long time. For a good laugh, call...

http://sci-e-research.com/geophysics.html

I love the way this guy puts "latent heat" and "crystallization" in quotes -- as if their existence were debatable.]

[JRehling]

Yeah, I don't quite buy it either.

It sounds like an explanation of Spiderman's powers. All very fine and well at the hand-waving level.