Deep Impact Predictions

maxtheknife · Jul 20, 2005

Yes, I've begun reading your links, Colesakick. Do I understand this correctly? Is the second image from the top left an electrical burst, followed by an image of 'nothing', followed by the actual impact?

a_lost_packet_ · Jul 20, 2005

colesakick - ..sun's electrical current to blast it in an attempt to equalize (think lighting on earth) the local charge gradient. The action creates sparks (the tail)... Are you saying that a comet's "tail" is composed of sparks? <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

yevaud · Jul 20, 2005

Apparently the effects of Kinetic Impact don't occur. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

telfrow · Jul 21, 2005

Packet: Update; mention of publication of findings... http://www.planetary.org/news/2005/deep_impact_tcm_0720.html Snip: These conclusions represent just the beginning of the scientific results of the Tempel 1 observation campaign. The first peer-reviewed papers to present new results from Deep Impact's encounter with Tempel 1 are now being written and submitted to Science magazine. Members of the Deep Impact science team and the international observers hope to see those first results in print by the time of the annual meeting of the Division of Planetary Sciences of the American Astronomical Society to be held in Cambridge, England, in September. The Planetary Society will be there for the latest news on this and other developing stories in planetary science. <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>

a_lost_packet_ · Jul 21, 2005

Thanks telfrow! I can't wait! I really hope they get that additional funding too! <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

yurkin · Jul 21, 2005

Comet Webcast JPL’s Comet Exploration Webcast tonight at 10PM Eastern I posted this over on mission and launches but I figure I’ll post it here too.

a_lost_packet_ · Jul 21, 2005

Thanks Yurkin! I'll definitely be watching that! <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

dmjspace · Jul 21, 2005

Let's hope somebody in the audience actually asks an intelligent question or two, such as: 1) Why didn't Earth based telescopes register an increase in water vapor after the impact, as expected by NASA's favored models? 2) Why did the debris expand into space rather than falling back down to the comet's surface, as expected in NASA's favored models? 3) Are you seeing abundant evidence of salts or highly differentiated materials in the spectral data, as opposed to the "pristine" ices NASA's favored model expects? 4) If Deep Impact detected no significant water vapor increase, and if the debris did not behave as expected, and if the materials are not pristine, are you prepared to include the "exploded planet hypothesis"--which predicted both observations--in your list of viable models? Of course, the answer to number four will be "NO" no matter what the answers to the prior three questions are. It should be interesting, nevertheless, to see how NASA force-fits unexpected data into the snowball theory.

dmjspace · Jul 21, 2005

Looks like the comet webcast is a no go. Or, if it is, it's starting very late (it's 7:40PM my time already). Or they're not showing it on NASA TV. Too bad. I was hoping to finally hear something new out of the Deep Impact team.

a_lost_packet_ · Jul 22, 2005

I don't know what was up with that. I faithfully tuned in to watch but all I got was canned programming. Oh well, I'll check one more time before I log for the eve. <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

centsworth_II · Jul 22, 2005

Maybe the Friday talk will be webcast? <div class="Discussion_UserSignature"> </div>

yevaud · Jul 22, 2005

Well, I'm merely an interested bystander, but I'll answer those as best as I can. 1) Why didn't Earth based telescopes register an increase in water vapor after the impact, as expected by NASA's favored models? Well, predictions don't always meet reality head-on. Not certain how to answer this, without listing an entire grab-bag of possibilities. Perhaps the energy imparted by the kinetic impact wasn't sufficient to liberate much actual H2O vapor. 2) Why did the debris expand into space rather than falling back down to the comet's surface, as expected in NASA's favored models? The gravity exerted by the Comet is quite tiny. Likely the energy of the kinetic impact exceeded that, which is why the debris expended outwards, instead of falling back. 3) Are you seeing abundant evidence of salts or highly differentiated materials in the spectral data, as opposed to the "pristine" ices NASA's favored model expects? Haven't yet looked at all of the data. Sorry. 4) If Deep Impact detected no significant water vapor increase, and if the debris did not behave as expected, and if the materials are not pristine, are you prepared to include the "exploded planet hypothesis"--which predicted both observations--in your list of viable models? Apples and Oranges here. The "exploding planet" hypothesis has effectively zero examples seen in nature (to be fair, I'll say, "as yet."). Besides, there's a problem with that hypothesis. There's something called the "binding energy," which in short is the energy required to crack a planet wide open. I did a research paper on this when I was in school. It turns out that the size (dependent on velocity, and hence collision energy imparted) is quite large. It would take an object the size of the moon (mor <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 · Jul 22, 2005

Yevaud said: Well, predictions don't always meet reality head-on. Not certain how to answer this, without listing an entire grab-bag of possibilities. That's why I keep saying prediction is the hallmark of good science. If a theory doesn't make successful predictions, the theory needs to be revised or discarded. Perhaps the energy imparted by the kinetic impact wasn't sufficient to liberate much actual H2O vapor. It was the nearly unanimous expectation from JPL and NASA teams (judging by all the pre-impact press releases I saw, and being familiar with the "snowball" theory) that abundant evidence of ice would be liberated from the 23,000 mph impact. The fact that it apparently didn't is clear evidence that the snowball theory is flawed, severely if not fatally. 2) Why did the debris expand into space rather than falling back down to the comet's surface, as expected in NASA's favored models? Did you look at simulations from the Lunar and Planetary Laboratory I posted earlier? The "gravity-dominanted" model favored by NASA required a majority (75%) of debris to rain back down to the comet's surface. The "strength-dominated" scenario, on the other hand (as required by the EPH), projected the debris to escape the comet. As far as anyone can tell from the available data on Deep Impact, the latter scenario is a better description of what actually happened. 3) Are you seeing abundant evidence of salts or highly differentiated materials in the spectral data, as opposed to the "pristine" ices NASA's favored model expects? Haven't yet looked at all of the data. Sorry. Well, there are no data to look at in this respect. We might not see it until this fall, after scientists have had a chance to publish their conclusions.

a_lost_packet_ · Jul 22, 2005

centsworth_II - Maybe the Friday talk will be webcast? I hope so. I'm really anxious to see a good news conference on this. Heck, if I lived close by I try to go to the conference myself. Dog gone it.. :/ I'm keeping my eyes peeled. If anyone gets a line on the conference webcast/broadcast drop a msg here. <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

colesakick · Jul 23, 2005

Who needs conspiracy when you have a reasonble explaination like this (regarding instrument problems ect. . .) Jul 22 thru Aug 07, 2005 Interim Report on Deep Impact Though many details remain to be determined, enough data is now in hand to offer a preliminary assessment of our predictions on Deep Impact. In our Picture of the Day posted prior to Deep Impact we registered the most detailed predictions of any group in anticipation of the event. For their part, NASA investigators made no predictions. Nor can we find in NASA’s subsequent comments any acknowledgement that an independent group had successfully anticipated the greatest surprises of the encounter. In view of this situation, we consider it essential that the remaining data analysis by NASA not be permitted to lag so far behind the event that no one will notice what has occurred. Nor will it be helpful if the data find their way into the public domain as isolated fragments of technical minutiae. Therefore, to maintain the integrity of the most fundamental questions we offer the following status report. Missing Water. Proponents of the electric model predicted that Deep Impact would reveal insufficient water to support the popular ideas about comets. Now we know the ejected material was largely—perhaps entirely—dust and vaporized rock. Subsurface Composition. We said that the “impact/electrical discharge will not reveal ‘primordial dirty ice,’ but the same composition as the surface.” It is now known that the presence of volatiles in the coma immediately after impact did not change, with the exception of changes relating to charge exchange between the coma and the solar wind (see below). High-Energy Explosion. Wallace Thornhill claimed that the energy of the “impact” would be greater than expected from impact studies, because of electrical discharge. When the predicted event occurred, it left every NASA investigator stunned. <div class="Discussion_UserSignature"> Intellectual honesty means being willing to challenge yourself instead of others </div>

a_lost_packet_ · Jul 23, 2005

...Creation of Water in the Coma. The electric model suggests that negatively charged oxygen from silicates and other metallic oxides on the nucleus (a negatively charged object) reacts electrically with the positively charged hydrogen ions of the solar wind to create OH. Thus, readings of the relative abundance of OH should drop in the immediate wake of impact, while in the days after the impact abundances of OH should rise. Though this is inconceivable under the standard model, preliminary data released does suggest this pattern. .. Water? OH? That's a nice hydroxide group they have there. Care to switch it around and add another hydrogen? <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

yevaud · Jul 23, 2005

I've long since spoken with a woman I went to BU with - she has a PhD in Space Weather. And she has looked at the data, and says "no, Megalightning did *not* bring down the shuttle." Just thought y'all might want to know. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

emperor_of_localgroup · Jul 23, 2005

@Colesakick Advance Flash. Thornhill predicted that a visible discharge between the nucleus and impactor would be likely prior to the impactor's contact with the surface. At least two flashes are now known to have occurred, though (for the obvious reasons) no one on NASA's investigative team had anticipated this. Is this true? I am all confused about this model debate. But the pic on your link says the picture was taken 97 sec after the impact, not before. And how is this flash of light different from the light we see when grains of meteor burns up as it nears the earth? I'm not trying to refute your claim, but to learn more. <div class="Discussion_UserSignature"> Earth is Boring </div>

dmjspace · Jul 23, 2005

stevehw33 said: And he totally ignored the comet density facts, showing them as having a density of less than that of water, as well as those of the asteroids, showing them to be, largely rock. What "facts" are you referring to? Actually, it is you who is quite good at ignoring anything in my posts that contradicts your grand proclamations. Comet densities and porosities are NOT known. There are guesstimates for a tiny handful, and sweeping generalizations for the rest. Worse yet, these guesstimates are based almost solely on the "dirty snowball" model, which has failed repeatedly to make accurate predictions. The only reason we know densities of certain asteroids is that we have pieces of them on Earth. We know almost nothing about comets...which is precisely why Deep Impact went in the first place. He never acknowledged those facts once! Not once! Because they so ineluctably undermine his silly positions on comets. Nor does he acknowledge the scores of passages of Tempel around the sun, which has resulted in the loss of much volatile material, including H2O, CH4, NH3 and others. So now you're agreeing with me that Tempel should NOT show evidence of abundant ices? Why don't you make up your mind? Which is it? Is Tempel a dirty snowball or is it an asteroid? His method is to ignore the facts, lets speculations and unsubstantiated claims intrude, and thus, can prove whatever he wants. No, my method is to cite known facts and make specific predictions. I don't see much of that coming from the resident pseudoskeptic society here, of which you might easily be elected president.

yevaud · Jul 24, 2005

Many ( in fact almost most) objects in space can become charged. Don't forget that we exist in a stream of charged particles that are part of the solar wind. The initial flash may well have been the differing potential between impactor and comet equalizing themselves just prior to the impact proper. And then the second flash would be from the kinetic strike. Of course, one might look at the light from meteors in the atmosphere as a sort of kinetic impact also - the meteor is colliding with the molecules in the atmosphere, and so burns up. <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 · Jul 24, 2005

Well, irrespective of the current debate, I frequently find myself fascinated by the dichotomy: that if one small aspect of known physics doesn't match predictions, some are eager to immediately jump in and say "all of physics is wrong. Here's a weird theory to explain everything." Disregarding the light we're seeing by, the computer we're posting from, the telecommunications that they use - all of which work just fine, based on those selfsame physics. Although the debate is, of course, usefull in hashing things out. But when someone says "because some aspects of predictions about <yadda /> don't meet predictions, therefore the "electric universe non-theory must be correct," I think, "that's like saying that because my cold medicine doesn't work well, therefore all of modern medicine must be wrong, and animism and appealing to the ten-thousand Gods is the correct way to cure the cold." Huh? <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

silylene old · Jul 24, 2005

Well, irrespective of the current debate, I frequently find myself fascinated by the dichotomy: that if one small aspect of known physics doesn't match predictions, some are eager to immediately jump in and say "all of physics is wrong. Here's a weird theory to explain everything." 'Intelligent Design' is yet another manifestation of the same irrationality, as applied to biology and the science of speciation. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

dmjspace · Jul 24, 2005

stevehw33 said: Bull! You were given at least 2 refs, including Wikipedia and NASA, both of which gave many supporting observations and even more references. You ignored those. I stated you would. I didn't ignore them. Here's what Wikipedia says: [The "dirty snowball" model] was confirmed when an armada of spacecraft (including the European Space Agency's Giotto probe and the Soviet Union's Vega 1 and Vega 2) flew through the coma of Halley's comet in 1986 to photograph the nucleus and observed the jets of evaporating material. The American probe Deep Space 1 flew past the nucleus of Comet Borrelly on September 21, 2001 and confirmed that the characteristics of Comet Halley are common on other comets as well. There's nothing about determining mass or porosity in there. Halley, in fact, raised many more questions than answers, including the surprise that it had multiple nuclei, precisely as predicted by the EPH's satellite model. Halley also had a sodium tail, which was completely unexpected in the snowball model but expected in the EPH. Like Borrelly and Tempel, Halley also had nowhere near the amount of ice it was "supposed" to have. I guarantee you will NOT be able to find a snowball model prediction regarding ice content in Halley or any other comet that turned out to be accurate. They don't exist. That means any guesses on density are virtually meaningless. NASA and JPL knows this, which is why even this rudimentary Wikipedia entry ends with this sentence: "Forthcoming space missions will add greater detail to our understanding of what comets are made of." In other words, we don't know what comets are made out of. The density data are clear for comets and asteroids. Untrue. Even the Tempel 1 Wikipedia article concludes with: "The purpose of the Deep Impact mission is to study the interior composition

dmjspace · Jul 24, 2005

Yet another reference confirming that comet densities are mere guesses comes from Cosmic Comets May Yield Secrets of Our Galaxy: Because the comet's [Tempel 1's] density is unknown, the size of the impact crater could range from that of a house to that of Rome's Coliseum. Says Prof Keith Mason, the director of the Mullard Space Science Laboratory at University College London: "Never before have we penetrated the nucleus of a comet. The resulting data should provide us with the most comprehensive set of scientific measurements ever obtained of a comet - unprecedented information on the genesis of our solar system." There is simply no way to know the composition of a body with certainty by remote sensing alone. But this was obvious to anyone really paying attention to the Deep Impact mission, for which NASA had ready at least a half dozen models assuming varying densities for Tempel, from "frozen smoke"-like particles to densely packed ice. So far, from observations of Tempel and every other comet we've gathered data from, there is no evidence that comets are significantly different from what we call asteroids.

robnissen · Jul 25, 2005

While I generally agree with most of your posts in this thread, I think you overstated the evidence in your last post. The link you posted actually states: "Density: PROBABLY between 100 and 900 kilograms per cubic meter (between 1/10 and 9/10 the density of water on Earth)." (Capitalization added). The fact that the range is almost a full order of magnitude, and that has PROBABLY added in front of it, sound to me like the listed density for Tempel is not much more than a guess.

Deep Impact Predictions

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