Deep Impact Predictions

JonClarke · Aug 30, 2005

vevuad We have first hand experience of four comets, not three. Just because the US had only sent missions to three comets does not make this the sum total of missions to comets. You forget that in 1986 five spacecraft flew past Halleys comet from Japan, the USSR and ESA. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

yevaud · Aug 30, 2005

Dang, you're right. My mistake. My emphasis in school was the formation and dynamics of planetary atmosphere's / atmospheric physics. ABCD laws and such like. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

yevaud · Aug 30, 2005

This still goes right back to a lack of evidence in either direction. We need more. The jury's still out on this, I'm afraid. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

dmjspace · Aug 30, 2005

JonClarke said: This is quite different to TVF. He is one researcher who has been pushing his barrow by him,self for decades. Actually, over the last 185 years, Piazzi, Lagrange, Olbers, Brown and Patterson, and Ovenden have fleshed out the theory. Brown and Patterson concluded there is irrefutable evidence that asteroids are part of a larger parent body. He has not convinced any of his peers and his ideas are utterly inconsistent with what is known about asteroid chemistry. This is a sweeping generalization. TVF certainly has his support among peers. He does not enjoy the numbers the dirty snowball proponents do, but who does? Despite popular misconceptions, science is not a popularity contest. But I am intrigued by your comment about asteroid chemistry. Please tell us what characteristics you note that are inconsistent with the EPH and favorable for the dirty snowball model. Did you know that TVF won a bet with Don Yeomans regarding asteroid satellites? How about the fact that Eros exhibited roll marks from deorbited satellites? Both of these were considered next to impossible in the standard model. The fact that no dirty snowball proponent is willing to even give the slightest nod of success to the EPH is proof enough of an extreme bias against it. If the correctness of the snowy-dirty-muddy-iceball is so compelling, why is there such resistance to "throwing a bone" to the challenger? By the way, still waiting for a snowball proponent to make a specific prediction on the Deep Impact data findings...

JonClarke · Aug 30, 2005

Lack of mechanism was not what stopped US scientists from accepting continental drift, it was lack of familiarity with the evidence. Partly an accident of geography perhaps, or provincialism on their part. It may not be coincidence that Holmes, du Toit, King, Carey, and others were all intimately familiar with Gondwanan geology, which requires continental dift to make sense. These people wrote in the 30-60s. If pointing out that fact that TvF's exploding planet theory does not fit the facts of asteroid geochemistry is a nasty attack then so be it. ususally when someone says that an attack is nasty in the face of factual criticism it is a sign that there are not facts to base a defense on. BTW comets hold lots of water, demonstrated by telescopic observations of hundreds of comets and space missions to five of them. The dirty snowball idea (that comets are mixtures of ices and silicates) is a fact. the exact proportions vary from comet to comet. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

JonClarke · Aug 30, 2005

Many asteriods are derived from larger parent bodies. Note the plural. There are more than a dozen chemical classes* that point to a similar number of larger (but still small) differentiated parental bodies. in addition there are a great many completely undifferentiated meteorites that have never been part of a large differentiated body, these are probably the majority. TVF and his supporters ignore these facts. Jon *added in edit: This refers to the metallic meteorites alone. If you add the various chondrite classes and asteroid famlies like the D and P classes that have no meteorite counterparts the number of parental bodies rises into the scores, perhaps even past 100. <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

dmjspace · Aug 30, 2005

JonClarke said: BTW comets hold lots of water, demonstrated by telescopic observations of hundreds of comets and space missions to five of them. The dirty snowball idea (that comets are mixtures of ices and silicates) is a fact. the exact proportions vary from comet to comet. Since nobody else has been willing, perhaps you'd like to post some very specific predictions about what Tempel 1 data will show? Preferably, what data can DI generate that will provide a test between the dirty snowball model and the EPH? Also, what test(s) would you propose that could potentially falsify the dirty snowball hypothesis?

yevaud · Aug 30, 2005

The fact that no dirty snowball proponent is willing to even give the slightest nod of success to the EPH is proof enough of an extreme bias against it. Oh, good God, man, we haven't been saying that at all. I've said repeatedly that if Van Flandern can begin his theory from different premise's, or find some actual hard data supporting EPH, then fine and well. I've said this at least 7 ot 8 times to you and CS. Nor have I once said that the concept of a "snowy dirtball" is preferable to a "dirty snowball." Not once. I frankly don't have an agenda here as to which is preferable, although you keep insisting I have one. For that matter, so does "Rob" at the Metaresearch board, and I don't even know Rob! And if you went around and actually looked you'd see that myself, Jon, Telfrow, and others all engage in very amenable and informative debates on a huge variety of scientific topics. You guys at that board try to paint us all with a broad brush. What I have said is that his beginning arguments for the EPH hypothesis is fatally flawed. Find another sbeginning premise, or rework the theory, or find some hard evidence. And that's all I've said is the issue. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

dmjspace · Aug 30, 2005

JonClarke said: Many asteriods are derived from larger parent bodies. Note the plural. There are more than a dozen chemical classes* that point to a similar number of larger (but still small) differentiated parental bodies. And is this what the solar nebula theory predicts? Or did it originally expect asteroids or comets, as groups, to be essentially homogenous? If it expected parent bodies to break-up (presumably only through collision), when did these break-ups occur? In other words, how are these observations more suited to the dirty snowball model, as opposed to the EPH?

JonClarke · Aug 31, 2005

The different compositional classes are derived from direct chemical analysis of meteorites. The existance of different classes are predicted from models of planetary accretion from planetisimals. Their composition helps us refine such models. The existance of a large number of parental bodies as demonstrated by chemistry is completely inconsistent with any form of the EPH. EPH would predict only a single source (maybe a few if you allow for moons and an impacting body). Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

yevaud · Aug 31, 2005

Thank you, Jon. Dmj, no one here is unwilling to debate and discuss EPH, but this is precisely what I meant. EPH does not take into count more things than I can even think of, and Jon's expertise in Geology and Planetary science now say this is so as well. As have I and as have Saiph. Three different people with varying expertise, and different (but all related) scientific specialities. We're not trying to discourage you. God, no. You apparently have a fine mind. You have focus and diligence. But this EPH concept is flawed. Please see that. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

JonClarke · Aug 31, 2005

I was at a presentation of Tempel 1 data last week by Mike A'Hearn. The spectrum from the impact plume showed a very strong water peak. This has has yet been published. Tempel 1 therefore must contain significant water. Water has also been detected in many other comets, some examples: LINEAR http://irtfweb.ifa.hawaii.edu/Science/lisse.pdf Hykutake http://www.submm.caltech.edu/~dcl/Refereed/1998Icar..133..147.pdf Hale-Bopp (and others) http://isowww.estec.esa.nl/science/SSR/Mueller.pdf Halley http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=31878 Ikeya-Zhang http://www.obspm.fr/actual/nouvelle/jun02/comete-odin.en.shtml Absence of water in cometary spectra would falsify the dirty snowball model. Since water spectra have been repeatedly found the dirty snowball model is confirmed, not falsified. Of course the actual snow/silicate ratio will vary depending on comet. Short period comets will have less ice, long period comets more. But Whipple's model has stood the test of time. It is now fact, just as it is a fact the moon is made of rock, not cheese. Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

dmjspace · Aug 31, 2005

JonClarke said: The existance of different classes are predicted from models of planetary accretion from planetisimals. The EPH says different asteroid belts are the result of multiple broken up planets. The planetary accretion hypothesis says asteroid belt are the result of multiple accreted planetesimals. There doesn't seem to be much of a difference between the two. The solar nebula hypothesis is no more proven than the exploding planet hypothesis, since neither has been observed. And can you point me to sources which predicted the various chemical compositions, rather than simply accommodated them as they were observed?

dmjspace · Aug 31, 2005

JonClarke said: I was at a presentation of Tempel 1 data last week by Mike A'Hearn. The spectrum from the impact plume showed a very strong water peak. This has has yet been published. Tempel 1 therefore must contain significant water. Isn't it true that even asteroids contain 20% water by volume? Isn't it also true that DI cannot determine the volumes of any material, including water, in Tempel 1? Water in the spectra is no surprise. But if a strong water peak indicates "significant" water, why didn't Earth-based telescopes find a net increase in water vapor post-impact? Water has also been detected in many other comets, some examples: The question has never been about water. It's been about the *amount* of water present. Absence of water in cometary spectra would falsify the dirty snowball model. It would also falsify the EPH, since the EPH expects water too. But Whipple's model has stood the test of time. Thanks for the links. They are interesting. Most interesting is the fact that, while there is plenty of discussion about the characteristics of that water (e.g. the percentage of "heavy water"), there is virtually no discussion about how much water is contained in comets. Since water spectra have been repeatedly found the dirty snowball model is confirmed, not falsified. Not according to the scientist interviewed in your ESA link, Max Planck's Horst Uwe Keller, who said: "We discovered that a comet is not really a 'dirty snowball' since dirt is dominant, not ice," Which is really all the EPH says...dirt is dominant in comets, just like asteroids. It appears to me that the fundamental problem we're facing here is that dirty sno

dmjspace · Sep 4, 2005

It's a bit disappointing JonClarke decided to exit this discussion. I'd really like to hear an "insider's" response to the questions about water I posed in my prior post. But I see JonClarke has more important things to do...namely, posting in the "a worst scifi movie ever" thread. <img src="/images/icons/wink.gif" /> Perhaps when the DI team writes their papers on Tempel 1, we'll be able to really get into the data rather than having to rely on vague statements like Lucy McFadden's "we found hot water!"

yevaud · Sep 5, 2005

Or even vaguer opinions, such as "an exploding planet terminated all of the dinosaurs." Nuff said. Dead thread. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

dmjspace · Sep 5, 2005

I see. So you don't see anything lacking in JonClarke's argument? C'mon, Yevaud, you're smarter than that. His only argument is that, since water is found in the spectra of comets, the dirty snowball model is confirmed. Bunk. The scientist in one of JonClarke's own references refutes his very premise, for God's sake: "We discovered that a comet is not really a 'dirty snowball' since dirt is dominant, not ice." This debate is sounding more and more like a political campaign than a scientific discussion. Double talk and data spinning and tools of the trade for people looking to get elected. They shouldn't be wielded in the scientific realm. JonClarke's setting up a false dichotomy, and he knows it. Asteroids have water too. The presence of water neither rules out the EPH nor "rules in" the snowball model. The lack of increased water vapor in Tempel 1's post-impact spectra, on the other hand, is extremely telling. It means the expected vast reservoirs of water were nowhere near the surface, as required by the dirty snowball model. That model's proponents will have to figure out where all the water is, likely by altering the model in fundamental ways yet again. The spinning, in fact, has already begun, as we see in today's NASA press release: NASA Finds Evidence Some Comets May Have Become Asteroids Tell me, how do comets "become" asteroids...unless they were simply asteroids to begin with? Remember, snowball supporters here insist that comets have densities that are far lower than asteroids. Recall stevehw33 and his "more than 4 sources" informing me that comets are light 'n' fluffy, not hard and rocky like asteroids. Well, which is it? Here's what the EPH says: Comets are merely asteroids with interstitial ice pockets. Otherwise, the two entities are virtually indistinguishable.<</safety_wrapper>

yevaud · Sep 6, 2005

Well, again, I think it's still hard to say. It's promising for the standard model, so to speak, that (as Jon said) a significant plume of H2O *was* seen. On the other hand yes, you are right, the jury's still out on that. Comets can "become" asteroids by accreting material over a long period of time. But that's terminology - it's still, at heart (no, not making a pun here) an icy body, but as you might see, once the rocky material begins to predominate, it will certainly "look" like an asteroid. So, they have to call it *something* - and asteroid it is. So, anyways, I think it's still hard to say. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

dmjspace · Sep 6, 2005

Well, JonClarke's not back to defend the "water means it's a comet" argument. It's probably a good thing in the end, since doing so is becoming harder and harder for dirty snowball propoenents. Two significant new articles are out today on Tempel 1, one from Space.com and the other from PhyOrg.com Neither bodes well for the dirty snowball model. According to Space.com's Robert Roy Britt, in the inappropriately titled article "Analysis: Deep Impact Comet All Fluff": Comet Tempel 1, hit in early July by an 820-pound probe, appears to be coated with fine powder rather than solid ice and rock. The powder is even finer than sand, scientists had reported shortly after the impact. This finding is a surprise to the standard model, but it is *precisely* what the EPH has argued for years. Comets and asteroids were formed in an explosive fireball rife with high velocity collisions and abundant carbonaceous "fallout." This fallout--which would have the consistency of ASH, (again, think burnt toast or charcoal)--should blanket the surface of Tempel 1. The fallout ash, a straightforward prediction of the EPH, also explains nicely the extremely low reflectivity of comets, which used to be thought of as shiny, brilliant, icy objects. Britt concludes that the comet "appears to be rather fluffy." But is that a reasonable conclusion? The whole thing is fluffy? Of course not. It's only covered with a lot of fluffy ash the probe had to blast through to get to a rocky surface. How else could the comet possibly stay together, unaffected in any significant way by Deep Impact's strike? The DI team still thinks the thing is held together by gravity, despite the overwhelming evidence that Tempel 1 is "strength dominated" because of a solid nucleus.

JonClarke · Sep 6, 2005

Since I am back it must be a bad thing. There are two things here. First is the EPH. The fact that there are scores, if not hundreds of asteroid parental bodies as indicated with different compositions is uttely fatal to it. The EHP started out with one exploding planet. if you postulate scores you have ended up with a view indistinuishable from everyone else. With a large number of parental bodies collisional distruption becomes likely. No biazzare, unknown mechanisms are needed. The EHP hyothesis becomes unneccessary. The second is the composition of comets. You seem think that I am saying that if it has water it is a comet, if it does not, it is an asteroid. If I gave that impression my apologies. What matters is the form of that water. Some asteroids do not contain water. Others, specifically the type C, do. This occurs as hydrated minerals. Comets contain free water as ice. This explains the major difference in behaviour between the two. Comets undergo major out gassing when at aphelion, because the ices volatilises. You get outbursts, tails, formation of a coma, fragmentation, all the phenomena that make comets interesting and unpredictable as a result. It is this activity, characteristic of ice bearing bodies in the inner solar system, that defines a comet. As ice is not stable in the inner solar system comets have to originated further out, past Jupiter, which defines the snowline for the solar system. You also wrote: "This finding [the fine surface materials of Tempel] is a surprise to the standard model..." Wrong. Comets have been known as sources of cosmic dust for many decades. You also seem to be under the impression that the "Dirty snowball model prdicst are particular ice-silicate ratio and a specific surface structure. Again wrong. The dirty snowball was proposed as an alternative to the flying sandbank hypothesis which suggested that comets were concentration or independe <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

dmjspace · Sep 6, 2005

JonClarke said: Since I am back it must be a bad thing. It's not a bad thing at all. In fact it's a pleasure to an SDC participant debate specific data with an intent to educate, rather than an intent to "win" the argument at all costs. There are two things here. First is the EPH. The fact that there are scores, if not hundreds of asteroid parental bodies as indicated with different compositions is uttely fatal to it. I still don't understand why, if this is fatal to the EPH, it's not fatal to alternative models. Did "solar nebula" models predict scores of different compositions? Or does it merely accommodate that data, as the EPH had to? The EHP started out with one exploding planet. if you postulate scores you have ended up with a view indistinuishable from everyone else. There is one big difference, as I understand it. The EPH breakups occurred far more recently than required by alternate mechanisms. The difference in time requirements of the competing models leads to very different predictions. The second is the composition of comets. You seem think that I am saying that if it has water it is a comet, if it does not, it is an asteroid. If I gave that impression my apologies. The EPH suggests that asteroids are no more than 20% water by volume. Ditto for comets, since they are basically the same thing. I am confused by what you're suggesting. What, exactly, is the difference between comets and asteroids, in terms of water content? More importantly, does the dirty snowball model *predict* any specific rock/water ratios, or does it merely accommodate whatever data come in by seeking to fit it into a preconceived notion about what comets "must" be? Comets undergo major out gassing when at aphelion, becaus

JonClarke · Sep 6, 2005

I have never read anywhere that the difference between asteroids and comets is based on a specific water content. It is the mode the water occurrs in and how it behaves that is important. Water in comets occurs as ice and therefore out gas in the inner solar system. Water in asteroids occurs in minerals and therefore out gassing does not occur. There is no reason why a particular body might contain only 10% water but, because occurs as ice and it enters the inner solar system is classed as a comet whereas another body contains 20% water as mineral phases and therefore does not outgas and is called an asteroid. I would not regard press quotes or even press releases as a reliable source of information on what people were or were not expecting at Tempel. I have had some experience of being quoted by the press and sometimes any similarity between what you said and what is quited is coincidental. Press releases are also often hyped -every Mars mission is said to be looking for evidence of water, for example. That is why I said you must look at sources other than the internet. The fact remains that comets have been known as dusty bodies for decades. this is not accommodation, this is fact. Why do you think that evolved terrain complete with craters was unexpected. If comets outgas every time they go round the sun then you would expect the terrain to be modied. This has been known since the 70's at least, when people started thinking about the surfaces of comets. Like I said, don't rely on web sites, read the literature. If you want to understand these things you have to get to grips with it. How many books have you read on comets and asteroids, for example? Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

JonClarke · Sep 6, 2005

Do you or do you not recongising the following as facts? Yes or no will suffice 1. There is not enough mass in the small bodies (comets, asteroids and dust) in the planetary solar system (ie. excluding the Kuiper belt and Oort cloud) to construct a planet larger than about 1/30th of the Moon - say twice the mass of Charon. 2. The geochemical evidence unequivocally points to scores if not more than 100 parental bodies. 3. The source of the asteroids lies between Jupiter and Mars. 4. The most plausible way to fragment a planet is through collision. 5. That the majority of asteroids and all cometary material as not undergone melting and differentiation (added in edit) Jon <div class="Discussion_UserSignature"> Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars Arthur Clarke </div>

telfrow · Sep 6, 2005

Deep Impact probe shows a fragile, empty comet Tue Sep 6, 2005 9:39 PM BST WASHINGTON (Reuters) - Comet Tempel 1, the target of NASA's Deep Impact probe, turns out to be quite fragile, with no more substance than a snowbank, scientists said on Tuesday. "The comet is mostly empty, mostly porous," said Michael A'Hearn, a comet specialist at the University of Maryland. "Probably all the way in, there is no bulk ice. The ice is all in the form of tiny grains." The material on the comet's surface, down to a depth of several dozen yards (meters) is "unbelievably fragile, less strong than a snowbank," A'Hearn said in a telephone news briefing to release early findings from the mission. The comet's dust and ice grains form a fluffy structure of fine particles held together loosely by a weak gravitational pull, the researchers said. The surface of Tempel 1 is pocked with apparent impact craters, features that have not been detected before on close-up observation of two other comets. Deep Impact collided purposely with Tempel 1 on July 4, freeing a plume of primordial material from its nucleus, the first time astronomers have been able to glimpse the interior of a comet. The smash-up with Deep Impact's washing-machine-sized probe was monitored by another part of the NASA spacecraft that flew above the comet, along with a European spacecraft called Rosetta and more than 70 ground-based telescopes. Scientists hope research into Tempel 1 will help unlock the secret of how life arrived on Earth. Variously described as dirty snowballs or snowy dirtballs, comets are prime candidates for seeding planets, including Earth, with water and organic material. An analysis of material in the plume showed a huge increase in the amount of molecules that contain carbon. This suggests that comets like Tempel 1 contain a substantial amount of organic material, which means they might have brought such m <div class="Discussion_UserSignature"> Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild. - Tennyson </div>

telfrow · Sep 6, 2005

Also see: Deep Impact mission reveals data of comet Tempel 1 http://news.xinhuanet.com/english/2005-09/07/content_3453803.htm Deep Impact space collision reveals comets to be fluffy balls of powder http://www.guardian.co.uk/uk_news/story/0,3604,1564078,00.html Deep Impact Adds Color to Unfolding Comet Picture http://www.physorg.com/news6258.html <div class="Discussion_UserSignature"> Made weak by time and fate, but strong in will to strive, to seek, to find and not to yeild. - Tennyson </div>

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