Wrong. Sources even say it's composition is "atypical". Here:
http:arxiv.org/pdf/0712.3314.pdf "The unique nature of the recent outburst of 17P does indicate that its composition and other properties must be atypical in some marked way."
My usage of "composition" came specifically in response to your original complaint/question about water content. In the paper you've provided here, the author is describing Holmes to be "especially heterogenous" compared to other comets in terms of various metals, minerals, and potentially gases -- so it's perhaps "atypical" in that sense (
overall composition). But you'll notice he also states its mantle is water-rich. The paper is replete with descriptions of water, both in content and as a catalyst. As such, this provides no basis for arguing that the comet is water-deficient, which is where you were trying to go the whole time (i.e., once again attempting to cast aspersion on the prevailing model).
Also, it's not only ironic but pretty funny that you selected this paper to try and make such a point, because guess what the author provides? A model possibly explaining Holmes's outburst, which could apply to other short-period comets as well. That's the intent. And you cite this,
"A novel mechanism for outbursts of Comet 17P/Holmes and other short-period comets", after proclaiming that mainstream astronomers
"are shrugging and saying we 'may never know the cause'".
http://www.nasa.gov/worldbook/comet_worldbook.html " A comet (KOM iht) is an icy body that releases gas or dust. ... snip ... The nucleus of a comet is a ball of ice and rocky dust particles that resembles a dirty snowball. The ice consists mainly of frozen water"
http://www.planetary.org/explore/topics/near_earth_objects/asteroids_and_comets/comet_facts.html "Comets are small, irregularly shaped objects composed of a mixture of rocks, dust, and what astronomers refer to as “ice” -- frozen water, methane, and ammonia."
http://www.noao.edu/education/igcomet/igcomet.html "Chemical composition of the nucleus by number, based on coma observations: • H2O ice is the main component (80-90%)"
http://www.yale.edu/ynhti/curriculum/units/1996/6/96.06.03.x.html "The nucleus consists primarily of water ice and solid carbon monoxide, with additional small quantities of carbon dioxide, methane, ammonia, nitrogen, formaldehyde, and hydrogen cyanide."
For that matter, name a comet that mainstream astrophysicists have concluded contained no water.
Since we were discussing water "abundance" versus "deficiency", I was using
"wet" to mean
"primarily composed of water ice". I wasn't attempting to suggest comets contain no water.
Preceding this...
You: And the mainstream model seems to need them to be all wet.
Me: I don't recall see anything requiring all comets to be wet.
I noted last time that you're reading too much into what these pages state. They're written like encyclopedia entries that speak generally about cometary characteristics. You're making the mistake of concluding from these rather brief synopses that in order to jibe with the mainstream model, they're
required to contain a certain percentage of water (or other) content with no little or no deviation.
The descriptions provided reflect cumulative observations, not some absolute measure of what a comet has to be. It would be equally misguided to pull up an article on asteroids and conclude that they
all must yield a specific albedo, or an article on spiral galaxies and assume they
all must fit a specific constraint on size or mass.
Since it doesn't seem to be sinking in, I'll say it again: with additional observations and measurements those estimates may be refined, and should that be the case these articles will be appropriately amended to reflect such.
You misstate the amount they found.
http://www.nasa.gov/mission_pages/deepimpact/media/deepimpact_water_ice.html. "The ice covered less than 1% of Comet Tempel 1’s surface and of that area only 6% consisted of pure water ice."
Not intentionally. I was referring to the observed on the nucleus but typed it out incorrectly without qualification. Regardless, what I was pointing out was the methodology involved, and my inadvertent mistake doesn't change its validity.
The only comet they've penetrated with a lander was Tempel 1.
And they can apply their findings to the distribution of water ice on other comets, comparing them against additional observations.
They did watch Schumacher Levy break up and saw no evidence of water.
Shoemaker-Levy 9. And, I don't think that's accurate (
see here).
Based on the ASSUMPTION that detected OH came from water. Electric comet theorists have suggested another possible source for OH.
You have this predictably backwards, most likely due to parroting the claims from sources like Thunderbolts without recognizing why they're wrong or understanding the ramifications.
The incorrect assumption being made here is by the EU proponents, who assert the solar wind carries a net positive charge. That's the basis for their attempt to explain the presence of hydroxyl in cometary observations, further claiming that they result from positively charged hydrogen in the solar wind somehow coupling with negatively charged oxygen from comet nuclei. But the solar wind is demonstrably electrically neutral, and these claims completely ignore or defy a myriad of observations. This attempted extension of their electrically-driven ideas to comets fails because their underlying assumptions fail.
Multiple, independent observations confirm that comets are the source of the hydrogen that's seen rather than what EU-ers claim.
Photodissociation of water isn't some new, mysterious thing that's been haphazardly invoked to explain observed processes in comets. It's supported by a tremendous amount of evidence. Your claim that this is just some wild guess being made simply has no merit. While I'm certainly no expert in astronomy or chemistry, this is fairly basic stuff. With very little effort you can pull up journal articles describing precisely why this is what astronomers see.
It's rather insulting that you repeatedly attempt to marginalize empirical methodologies as mere "ASSUMPTIONS" while eagerly accepting truly wild, ridiculous assumptions and assertions from EU claimants. They advance egregious premises that wholly contradict existing observations and data, include alleged phenomena which have never been observed, and fail to make any measure of cogent, reliable prediction.
But it's bogus to claim this confirms there is lots of water in all comets. And if there isn't, then explaining the jets in those cases becomes problematic for the mainstream model. Wouldn't you agree?
Nope.
Then how does a mainstream comet create a tail full of OH if there's not lots of water?
Please take the time to format your quotes correctly. The text in red is yours I quoted in a
prior post. The text in blue is the one word of my answer you bothered to include.
The comet you describe in this part of the exchange is Tempel 1. Ample quantities of water exist in Tempel 1 to account for the observed OH.
Then here's another challenge for you. Find a mainstream source that does lay out a believable mechanism by which the ice deep in a comet can be vaporized by heat from the sun to create those stunning jets and tails given the excellent insulating characteristics of the surface materials on comets.
You already linked to
one hypothesis applicable to short-period comets, perhaps without even realizing it. I already stated that the specific cause of cometary outburst events is not known, and is being studied. That however does not negate what
is known about comets, nor does it require we discard the sum of physics and chemistry to embrace your fringe cosmology.
Your introduction of this issue is just a diversionary tactic anyway. Going on the
MAINSTREAM BAD! offensive by making others jump through unnecessary hoops keeps the focus off of why the EU ideas, to which you're so attached, fail. Whack-a-mole is particularly tiresome as is and that's exacerbated when when you go on to ignore or reject the explanations, references, and resources which negate your position. You display a consistent penchant for attempting to shift the burden of proof.
That's a mighty important item ... too important to have no other answer than "study continues". I hope they don't invent another gnome to explain it.
If you'd bother to look, you could find articles devoted to the study of cometary jets (it took me about five seconds to find several entries
like this). The specific mechanisms are not known
yet, but will be better understood in time, if not specifically identified. This process takes time because we have somehwat limited opportunities to observe comets in comparison to other celestial bodies. What you're doing yet again is focusing one small aspect of a large picture and trying to leverage an unknown to dismiss that which
is known. You have completely unrealistic expectations. If you put half the effort into understanding physics and astronomy that you do bashing it, you might have a better grasp of why EU claims don't withstand scrutiny.
They based that claim of 4500 tons on OH measurements. But as I've noted, electric comet theorists suggest there is another explanation for that OH ... one that doesn't involve water.
And that alternate explanation is untenable for reasons already described.
And the SWIFT team concluded that 250,000 tons was released. That's quite a difference from the other estimate.
Yes, it is -- because they used different instruments on different spacecraft over different time spans.
And they based that on the ASSUMPTION that x-rays that were measured were the result of water being lifted into the solar wind.
I think you similarly underestimate the accuracy of this observational method.
Refer to this (Thompson explains it far better than I could hope to).
First of all, charge exchange doesn't require the neutral atoms be water. Second, electric theorists have suggested a different source of the electrons producing x-rays in comets ... one that doesn't require water or neutral atoms. Third, sources on these SWIFT results have noted that the long period of increased X-ray emission is puzzling because views of the comet at optical wavelengths suggest out-gassing died down relatively shortly after the impact.
What we have are
different interpretations from scientists studying the same observations. I don't know how close they've come to rectifying their views in the time since the article was published.
Your line of argument sidesteps the original point though, and you're choosing to focus on more minutiae. Regardless of the methodologies employed by the Deep Impact mission and contributing observatories, no matter how you slice it, plenty of water has been observed in the case of Tempel 1.
More importantly, even if
all the analyses were somehow discovered to be flatly wrong,
no veracity is added to the claims made by EU proponents as a result, cometary or otherwise, because those fail on their own (lack of) merit. As has already been
brought to your attention, there's nothing resembling an actual "electric" model for comets presented by the sources you insist on citing -- just a lot of handwaving from people who don't understand or wrongly reject established science (including the overwhelming evidence which contradicts their claims).
Fourth, have you done a calculation of how big 250,000 tons of ice would be? Even without considering the very low density that the mainstream astronomers claim the Tempel 1 comet has, that much ice would be bigger than the crater they claim has been carved out of the comet. Explain that, please.
I think you (like McCanney) mistakenly assume that the volume of water ice observed by the SWIFT team would have to be confined to the ejecta released from impact. From their published results:
Willingale et al said:
It could be that either this water was produced from the surface several days after impact or the impact liberated the water as slow moving ice grains rather than gas. Ice grains with sizes in the range 1-10 µm were observed in the ejecta of the impact, but the lifetimes of grains this size are only a few hours.
...
Similar areas of other volatiles including carbon dioxide may have been exposed by the impact producing a temporary increase in the molecular outgassing rate. A thin ejecta blanket deposited on the comet surface by the impact to form evaporating ‘‘snow banks’’ would be difficult to see in reflected light but could be responsible for a significant
increase in the outgassing rate.
...
If this outburst was caused by the DI impact, water ice or other volatiles must have been exposed at the surface by the collision or initially shed as small grains rather than neutral gas. The exposed surface and/or the grains then sublimed over a period of 12 days.