Has it been definitively stated there was no water in the secondary plume?
Or no more detected than before the impact?


- Bob

http://www.ssc.se/default.asp?divisi...00577144355393

So the actual data indicates that there was little water vapor in the plume, and in fact the dust plume appears to mask the water vapor seen streaming away from us before the probe impacted.

Here are some before and after spectra:

http://www.ssc.se/data/content/IMAGE...dinspektra.PDF

However, the article continues:
No! No! NO!

There is no reason whatsoever that the distribution of molecules within the dust plume would mask significant water vapor within the plume, that is just plain bogus. DATA should aways trump theory, and expectations based soley on theory should not cause us to discount what we have observed.

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jwj

It's ok not to know. We should try harder to find out.

If the outer ring of the cratering plume were composed primarily of surface dust shot outward in the initial impact with the water vapor composing the central spire of the ejecta having been stirred up at the direct point of impact.

Its possible, how likely is open to debate, based on what you believe the distribution of material within the comet is. Which makes it all the more unfortunate that the crater won't likely ever be imaged.

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

They sound more like tarballs to me. I think the thing is held together chemically rather than gravitationally. If it is as porous as the researchers are saying, why any cratering at all? Shooting a porous material usually results in a clean hole with straight sides. The material needs some brittleness to crater.

Just my opinion.

Brittleness, or surface resilience? I guess we are stating the same argument. If Temple 1 has the density they have calculated, it is 90% void.

I just listened to the Planetary Societies' interview with PI Jessica Sunshine. Sunshine said the moisture readings increased by a factor of 10 during the impact, and the 'dust' by a factor of 20. She also said that a periodic jet that should have started just before the impact skipped a cycle. Did it skip a cycle, or was some of the moisture measured during event the the result of the jet, not the impact? The article I quoted above makes it clear the main column of moisture appeared to be 'behind' or shielded by the plume. (Other reports have indicated that the jet would have been on the 'far side' when it erupted.)

The other curious thing is, not once in the ~15 minute interview was it even mentioned that the comet ejecta contained significant amounts of clay - they only mentioned water and organics, which is pretty much what the comet was expected to be made out off before the impact. As I understand it, the ejecta is dominated by silicates and ferro-silicates.

"So is the characterization of a comet as a 'dirty snowball' still intact?"

"Pretty much..."

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jwj

It's ok not to know. We should try harder to find out.

To me, the good news is that there are definitely things like hydrocarbons and ammonia in these wee beasties. Even better, NASA seems inclined to go whack another one. Maybe we'll have better luck with the next set of observations.

No mention of ammonia in the Sunshine interview, either. Ammonia is a surprising no-show on Titan. I listened to the Planetary Society interview again, just to make sure. Their is no mention of the water / dust increase, only that the 'organic' volume released increased 20 x and water and C02 increased 10 x.

Did I miss something somewhere? Did they decide there was not a release of clays - silicates and pyrenes?

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jwj

It's ok not to know. We should try harder to find out.

Personally I can not see how you made the gigantic leap from the bit where they originated in a region where they may be solid(etc etc)
add gigantic leap of `logic' here....
to

The obvious implication here is that the water contained in comets has never been unfrozen, therefore,
insert wild guess here

what the???

the ice in my freezer originated in my freezer.
The obvious implication here is that the water contained in my freezer has never been unfrozen, therefore,
all ice originates from my freezer!!

DEAD Wrong!

(i know i know its a strawman-but jeez... simple logic seems to have gone on xmas holidays it seems)
say something like i boppa believe all ice in the universe came from my freezer and uses a torturious path to point back at my previous statement as proof is mildly `unusual' i would have thought..

but its obvious...

and equally obvious is its
DEAD Wrong!

;-)

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Surely if you are going to start a conspiracy theory it is best to start with something that might have a grain of truth or reality in it. To start with the preposterous and go downhill from there is just stupid. steve(primus) (Avatar)

j.j
im assuming that option 1 in your list isnt one of your prefered options
or are you assuming that temple 1 in particular(and by your quote every comet??) only does a single `death plunge' towards the sun and there dies a fiery death

or possibly you are actually admitting that you find that a comet

Web definitions for comet

(astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit
wordnet.princeton.edu/perl/webwn

may possibly have come in close to the sun and then gone away again-even several times even?

wouldnt this `orbit' thingo consist of a warmer past for this(and indeed most if not all other comets' at times???

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Surely if you are going to start a conspiracy theory it is best to start with something that might have a grain of truth or reality in it. To start with the preposterous and go downhill from there is just stupid. steve(primus) (Avatar)

I don't have any strong feeling, theories, what have you, on what a comet should or should not be. I am just bumping my old texts up against the observations. The clays found in Tempel 1 form at relatively high temperatures ~450 k, (or was it C?), These were unexpected.

Also unexpected are the small particle size of the dust.

But what was perhaps most unexpected is the extremely low thermal inertia - the fine particles of blackened sand in a high-void matrix make a great insulated black body, and the nucleus cools immediately when the sun is not shining on it directly. This makes it difficult to explain how the clays formed (therefore, they ARE most likely 'primal'), but it makes it even more difficult to explain what causes the jetting: If no heat is absorbed, why do jets, when they are not facing the sun, jet???

Prior to Tempel 1, it could have been argued that the as they rotisserate, pockets of moisture deep in the nucleus are heated like kernals of popcorn. But if very little solar energy is absorbed, (as the thermal inertia indicates), no popcorn. Very curious.

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jwj

It's ok not to know. We should try harder to find out.

It might be a photochemical reaction that is delayed. That's the only thing I can think of anyway.

I'm curious why you thought this was surprising. It would seem to me that if comets were born in the dust cloud from which the other planets formed, yet had not changed substantially since then, that such a composition would be expected. These bodies are not massive enough to self compress from gravity, so there's no reason to expect the particles composing the comet to condense into more solid form. The coma could then be more easily explained as these fine particles held in suspension around the nucleus through weak ionization charge from interaction with solar wind rather than heat evaporation.

Just a thought, anyway.

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

I think you're possibly right in your assumptions, but the major problem I see is that the images of the comets we have seen to date, all imply a very cohesive (if not downright rocky) surface. Craters, steep cliffs and spires are not to be expected when the major constituent is dust. And then again how are the highspeed collimated jets formed (even apart from the question how the heat is supposed to get to the assumed ices/volatiles)? It makes no sense to me whichever way you look at it from the Whipple (dirty snowball, or dusty whatever-ball) point of view.

Cheers.

There's enough cohesion in particles of talcum dust to form craters with walls that appear to be more substantial, as if they were solid, when you drop something into a pile of powder. Given that your talking about cubic miles of the stuff in pretty much microgravity, then those whispy features can assume a pretty grand scale, since gravity isn't there to pull them back flatter. Also, its an irregular body, so lacking a consistent shape from which to vary, the "spires" and "valleys" could be nothing more than incidental effects of how the material first clumped together, rather than something that formed later.

As far as the jets, let me partly backtrack myself, there does exist the possibility of compression to more solid form at the point where something impacts upon the nucleus. Over a few billion years, its possible to generate those clumps of ice from whatever liquefication and freezing occurs from impacts to create the sources of the jets (this localized clumping of ices could explain why the locations of some jets are consistent from one close pass to the next).

As far as heat transfer? Beats me, I guess there could be an element of heating as well as ionizing, since the coma might get to be substantial enough for thermal transfer, but I'll leave that to more educated minds than my own.

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

Yes, in retrospect, no one should have been surprised by dust, especially since the moon is so dusty, but no one predicted it. I would suppose because in previous close comet encounters (Wild 2, and Halley's), the surfaces looked pock-marked and rocky, not dusty. I'm personally at a loss to try and explain why the jets produce so much moisture, and the impact so little.

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jwj

It's ok not to know. We should try harder to find out.

Perhaps the jets are coming from deeper inside the comet. The DI probe didn't penetrate that far inside.

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I'm not a scientist, but I play one on the internet.
http://www.rrac.org

I suggested the dustiness partly because of the precident set by Hyabusa and the other American probe that had a close encounter with an asteroid (having a senior moment, so please bear with me), those both reported that the asteroids they encountered were really no more than a conglomeration of boulders and dust that appeared to be completely solid. This in spite of the fact that their appearances clearly looked like your traditionally assumed solid rock, complete with cratering.

Based on where the conversation was going here, I just connected the dots and came up with that possible conclusion.

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I'm not completely heartless, the doctor who removed it told me he'd never be able to get it all.

Sorry Doodler,

I have to disagree with your view on the cohesiveness of talcumpowder-sized dust grains, such dust can't take any pressure from inside, and that's where supposedly jets originate. The dust would simply be pushed away and never form the highspeed collimated jets that are observed.

Cheers.