Saturn Moon Continues to Delight and Baffle

vic_1066 writes to tell us that BBC News is reporting on the many interesting discoveries made by the Cassini probe. The Saturn moon, Enceladus, apparently continues to provide confusion and excitement for scientists the world over. The Cassini probe has been making waves ever since its arrival to the Saturn system.

Comments

How many more moons are there?

[Anonymous Coward]

As best I know, they keep finding new moons in the Saturn and Jupiter systems. Is it possible that there are more to be found?

For those who care about who...

[rob_squared]

...the moon is named after:

"In Greek mythology Enceladus was a Titan who was defeated in battle and buried under Mount Etna by Athena."

Great things come in small packages

[lightyear4]

These are the things that make this universe so incredible! Nature may be governed by general laws, but she will never allow a dull moment

For such a tiny moon (its only 500km across), this one packs plenty of surprises. This oddity has: a localized hotspot at its southern pole, a largely water vapor atmostphere with some interesting trace compounds, and most intriguingly, a spot on the very short list of places possibly harboring life.

Absolutely intriguing - congrats to the Cassini team for their achievements.

It'd be interesting

[krymsin01]

if the source of the heat turned out to be a natural nuclear reactor, like Oklo. I doubt that's a possibility, since I would think it'd put off a lot more heat if it were.

Re:It'd be interesting

[MichaelSmith]

I think this fact also VERY likely precludes the existance of a natural nuclear reactor at Enceladus now as well.

How about a recent cometary impact? It might have created a pod of water under the surface of the south pole, which is slowly leaking heat and water into the outside.

Stephen Baxter incoporated this idea into his book Titan, and suggested there might be ice packs above a deep body of water. In the case of this small moon I would suggest that the heat pulse from the impact would spread out slowly from the impact site, but it would tend to release energy through fractures close to the point of impact.

Cracks me up

[Markus Registrada]

I love reading these NASA and JPL press releases.

"Scientists are baffled! We can't account for polar heating / overlapping flat-bottomed craters on Mars / volcanoes drifting around the surface of Io / particles blasting out of the sun at a quarter of lightspeed / gullies that cross over one another / the enormous explosion out of that comet!"

Of course they're baffled. They won't let anybody competent explain it to them. These guys never studied plasma fluid dynamics in school, and they figure that now they're too old to learn it. Anyway the math was too hard even back then. If they had even one experienced plasma physicist on-staff (or took his gag off) they'd have easy explanations -- at least the beginnings of them -- for most of these things.

As it is, every time they run across something that's unavoidably electromagnetic in character, they're absolutely astonished. Then they instantly forget all about it. Each time, they're astonished anew. Yet it never occurs to them that any new impossibility could also involve similar stuff.

Here's a hint: is there a magnetic field somewhere nearby? That means there's electric current, too, either generating it, or at least being induced by the (conductive) moon moving through it. Where's it flowing? What sort of ions are carrying it, and are transported by it? What happens when they hit a planetary surface? What happens when a charge builds up for a long time, and then gets released? Polar heating... hey, guess where auroras happen? Look at Saturn's poles, in x-rays and infrared.

Jeez. What do we pay these mooncalves for, if they're afraid of fluid dynamics maths? Hire somebody mentally better-equipped.

Re:Cracks me up

[Markus Registrada]

Your first image is not from Mars. It's of a catena on Ganymede, and the chain is about 150--200 km long.

Fine. This makes an enormous difference, doesn't it?

... Shoemaker-Levy 9. We watched SL9 break up and impact Jupiter, producing similar "features".

For a sufficiently dissimilar grade of "similar". Jupiter doesn't have any craters that I know about. (Maybe you have private information.) SL9 pieces hit thousands of miles apart. What broke up something, but kept all the bits right next to one another and right in a perfect line, and furthermore arranged they would all hit at precisely the same instant? And what happened to the stuff that was in the holes?

... our second image is perfectly consistent with aborted graben formation ...

They don't look anything like the grabens we know about, although they do look like other things called grabens on, e.g., the moon, which begs the question. (Expand your definition enough and any hole is a graben.) Anyway, Mars (like the moon) is supposed to be geologically inactive. How long are these things supposed to have been there?

our third image is...consistent with the breakup of a comet or asteroid before impact

An exceptionally well-trained, tidy, and cooperative comet, evidently. Notice the perfectly-formed ridges between craters ("graben"?), and the lack of ejecta.

As technical as it may seem, your reply amounts to, "I can't handle big numbers where electrical phenomena are involved." There's no denying that the amount of energy you quote carved out those cavities. It certainly can be terrifying to contemplate lightning bolts that large, but no more so (if you think clearly) than the corresponding rocks zooming about.

Deep Impact: The predicted impact size was about not more than ... [yadda yadda]

The amount of energy released was several times the largest value predicted and, in particular, much larger than could be accounted for by the kinetics. (Kinetics is a pretty mature topic.) I note that you don't address the flash that occurred prior to (what I would interpret as) impact, or the x-radiation. The one-mile-deep burrow wasn't my idea; it came from a JPL press release, as an explanation for the delay between the initial flash (interpreted as impact) and the ejecta. As you note, it's obviously silly, which demonstrates my own original point nicely, thank you.

The only way the amount of volatiles could square with expectations is by out-and-out revisionism. Before impact Tempel was described as a "dirty snowball" (or "snowy dirtball" by more lately fashionable models), and the ejecta was predicted to be mostly, or largely, volatiles. (The disagreement was just over whether it was mostly snow, or maybe as little as a third snow.) Instead, there were only traces, and it is now acknowledged to be a rock and not a snowball at all. Now the "cometary jets" that were supposed to be suddenly-vaporizing pockets of volatiles are entirely unexplained (again). Now everybody pretends they knew that all along.

It cannot be a "waste of taxpayer money" to publish papers: researchers pay "page fees" to publish. Considering what does get published, any suspicion about the ultimate correctness of the ideas contained obviously has little or nothing to do with the decision to accept or reject. To reject a paper because you quail at the amperage implied is inconsistent with the bold spirit of inquiry. If this was science, you'd publish the stuff you disagree with, and other papers that show what's wrong with it, and any that show what's wrong with them. Censorship is for churchmen and cowards.

Re:Cracks me up

[Markus Registrada]

If you have a an explanation - write it up. Become a famous planetary scientist.

A famously unemployed planetary scientist, it looks like. You have get papers accepted in peer-refereed journals, and draw peer-refereed NSF grants, to stay employed as a scientist. (Of course these "peers" haven't studied plasma physics.) One might as well apply for a grant to study the cause of DNA damage in brain tissue exposed to low-magnitude modulated microwaves.

Actually, I happen to know there are some very competent electrodynamicists on the Cassini science team (these folks, for example), and no doubt they'll be involved in vetting hypotheses.

Or they'll be told to sit down and shut up, as they evidently have been so far. They know better than to stick their necks out. It would be easy to tie them to cranks and biblical literalists.