Plumes on Enceladus!

[Malenfant]

Well they didn't find plumes at Europa, but they sure seem to have found something at Enceladus now! Quite amazing considering the small size of the moon, but it does look like some kind of active eruptive process is going on there - thought this was suspected since it was clearly the source of material from the E ring.

Full details at: http://ciclops.org/view_event.php?id=45&flash=1

[Dollan]

Absolutely and wonderfully amazing. I mean sure, we all suspected something like this (as I recall, there was speculation of Io having volcanoes before the initial Voyager discovery), but to finally see them, active, and emanating from the warm region....

Wonderful!

...John...

[Malenfant]

tis pretty darn cool, isn't it . I remember people being somewhat disappointed that they didn't see any on Europa while I was in the US working with the Galileo SSI team... i'm wondering if that was just a case of bad luck/bad timing for Galileo now? Could Europa have plumes like this too, and we just missed them?

[Dollan]

I don't know. Galileo seemed to put in a lot of time covering Europa. Or maybe it just seems like it? If there *is* a global ocean under that ice, I wonder if it would be able to persist for billions of years and still have active geysers.

What I really want to know (aside from what seems to be driving all the dynamic activity in the Saturnian system) is where does this ejecta on Enceladus come from? Subsurface liquid or sluch reserves? Is there enough gravitational interaction between all of the Saturnian moons, and Saturn itself, to perpetuate cryo-volcanism? And if so, why is only the southern hemisphere active?

So many questions, so few probes.... I remember when I used to think that the Saturn system was vaguely boring!

...John...

[Malenfant]

I don't know. Galileo seemed to put in a lot of time covering Europa. Or maybe it just seems like it?

I think it just seemed like it. Remember, Galileo had the screwed up high gain antenna which means it couldn't monitor its targets all the time on approach or while it was approaching something else. I think we actually got about 1 out of every 20 images that were originally planned (heck, when Cassini flew past Jupiter on the way to Saturn it returned more images of Jupiter than Galileo had for the previous 5 years).

So it wouldn't surprise me if the few snapshots we got of Europa at high phase angle might have been just taken at the wrong time or the wrong angle or looking in the wrong place, because we only have a literal handful of images that actually looked for plumes.

Given the apparently tidal origin of some of the cracks on Europa's surface (the cuspoid ridges), it always did strike me as somewhat surprising that we didn't see any evidence of current activity. Particularly when the theory for their origin implied that they were still actively being created by tides.

If there *is* a global ocean under that ice, I wonder if it would be able to persist for billions of years and still have active geysers.

That's a headscratcher for me too. Maybe radiogenic heating + tidal heating is enough even in such a small body to keep its interior liquid? We know that Callisto has an ocean too even though it's not tidally heated - but it has a lot more rock to act as a radiogenic heat source than Enceladus does.

So many questions, so few probes.... I remember when I used to think that the Saturn system was vaguely boring!

I suspect that Cassini will be targeting Enceladus a lot more (probably in an extended mission, which has got to happen unless Bush's funding plans for his crazy manned missions get in the way - which is actually ooking frighteningly possible) so we may get some answers...

[ElChristou]

... but it does look like some kind of active eruptive process is going on there...

Another nice effect we need to implement in Celestia...