CometWatch 10 January

This four-image mosaic comprises images taken from a distance of 27.5 km from the centre of Comet 67P/Churyumov-Gerasimenko on 10 January. The image resolution is 2.3 m/pixel and the individual 1024 x 1024 frames measure 2.4 km across. The mosaic is slightly cropped and measures 4.2 x 3.8 km.

navcam_mosaic_20150110

Four image mosaic comprising images taken on 10 January 2015. Rotation and translation of the comet during the imaging sequence make it difficult to create an accurate mosaic, so always refer to the individual images before drawing conclusions about any strange structures or low intensity extended emission. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

The image shows the smaller lobe of the comet in the lower left corner, and the larger lobe to the upper right. The smaller lobe is actually in the foreground, and its rotation over the time elapsed between the first and the fourth frame is significant, making the mosaic particularly tricky.

The intricate patterns of pits and other roundish, hollow features on the larger of the comet’s lobes stand out beautifully in this view, along with a number of boulders, particularly on the smaller lobe and across the neck.

The four individual 1024 x 1024 frames, along with a montage of the frames, are provided below:

Montage_20150110

ROS_CAM1_20150110A ROS_CAM1_20150110B ROS_CAM1_20150110C ROS_CAM1_20150110D

Comments

52 Comments

  • Steve Kasian says:

    Dead center there are 2 distinct jets visible exiting their source! Based on the distance to the nearest shadow terminator, it would appear that the sunlight is illuminating these jets within mere feet of their source at the surface. These are the first jets this narrow to be seen thus far that can be seen all the way down to their source. Unfortunately, the source is in shadow and can’t be seen. I’ve increased the brightness & contrast to make it as visible as possible here:

    https://mega.co.nz/#!zQVmHZbC!vItTPR9zO_6KHsVXZgODl9NXHJDU-SMcAGS1Xe-1L1U

    • Leo Vuyk says:

      Steve : congrat. for:
      These are the first jets this narrow to be seen thus far that can be seen all the way down to their source.
      Indeed it look as if the jets emerge out of a pipe!

    • Graham Hall says:

      Well spotted, but while you say “unfortunately the source is in shadow” in my view its because the source and the jets are in shadow and only illuminated by reflected light that you and now we are able to see them. Images from previous comet encounter plus image from 67P have shown jets but very much against a black background. Close up they are less visible. Well done!.

    • Daniel says:

      Just to clarify, dead center here is not exactly on the pixel in the center but rather a tiny bit down and to the right of the center in the mosaic. It is very faint, But with a high contrast/brightness you can see two apparent jets there.
      If you take a look at the individual frames then they are in the ‘D’ frame. They are in the shadows directly to the right of the new circular features that can be seen in the valley.

      Very interesting, but I think I will leave the speculations up to someone else.

  • Ross says:

    This image supports the electrical model without any doubt.
    In the center of the neck region you can see two similarly sized crater-like depressions, followed by a smaller crater on its rim. This is a common pattern seen consistently in crater fields on all planets and moons. Then just a bit up and right from this feature is a well-lit cliff. The edge is lined with circular depressions. This scalloping of crater edges is also seen on every planet and most moons. These depressions are the footprints of the jets. Electric discharge machining of a charged surface produces all of the observed phenomena. The discharge sputters along the nucleus always leaving circular depressions of an even depth.

    This cannot be caused by impact theory, which is assumed amongst the planets and moons. It cannot be sublimation, leaving uniform depth, circular depressions overlapping in fine dust.

    I cannot wait until this summer when the increased activity will make this perspective painstakingly obvious.

    • buck rogers says:

      You are right. Obviously the ideas we had about comets don’t explain the findings of the rosetta mission sufficiently.
      The theory favorited by many posters here (seeing comets as highly charged, rocky bodies electrically interacting with the sun’s plasma if I get that right), on the other hand, still leave many questions unanswered, like:
      If the comet is much denser, where is the mass/gravity?
      How does the electric discharge work on such a large scale?
      How does it not lose the electric potential flying through the plasma sun wind?
      And with the enormous forces necessary, how do they not affect (even destroy) the instruments as well as the rosetta probe itself …

      “Obviously” there is no ice on the surface, which is extremely hard, but the comet as a whole has a low density, so it appears to have a protective shell. As you stated, the depressions on the surface are not impact craters, nor can they be caused by sublimation.

      The comet increases it’s activity as it approaches the sun. Organic molecules have been found. It’s about time to think in a different direction as to what comets really are, the evidence is growing stronger with every day of the mission. We will need to rethink our concept of what life is, as well.

      • originalJohn says:

        You are asking all the right questions buck rogers and your understanding of the theory of comets as charged electrical bodies ….etc is correct.
        The mass measured for this comet and therefore the density is a serious anomaly as it does not fit with the normal dense rock appearance. This needs thorough investigation ie many repeat mass measurements as well as measurement of the physical properties of the rock.
        An electric discharge can work on any scale.
        It does lose electrical potential as it flies through the solar wind. That is the electrical discharge that we see. At some point nearer the Sun it may reach a charge balance and fade dramatically.

        It is intense current that would cause the damage rather than a force. If the orbiter intersected a dense current flow it could indeed be seriously damaged or destroyed. This could happen if that current flow is not recognised and mapped.
        Note also buck that there are no apparent exit “nozzles” on the surface for the gas theorised to be coming at high speed from ice hidden beneath the surface.

        As above, activity may not necessarily increase near the Sun. If the potential drops a lot it will decrease, possibly even to nothing. Then activity could increase when the more positively charged comet returns to the more negative region of the heliosphere. Previous comets have brightened or even exploded in this region, near Jupiter.

      • Ross says:

        The achieved density is calculated indirectly through the gravitational forces acting on Rosetta. This may shed light on the relation between gravity and the electromagnetic force which Faraday sought after.
        The electric discharge works on large scales just as it does on small scales. Research plasma scaling and you’ll see that this strongly supports the plasma cosmology perspective of the universe. Discharges do not. Only occur in arc modes seen in lightning, glow mode (St. Elmo’s fire) and dark mode are also present.
        Enormous forces are not required, the electric field of the sun is very weak, yet proves substantial over the large distances. It is a fact that the Saturnian moon Hyperion is negatively charged, which discharged with Cassini from over 2000 km away. The comet becomes most active when the change in voltage is the largest, which happens to be near the orbits of Jupiter and Saturn. If this were true then we’d expect events to occur as the comet is moving away from the sun as well… and this is exactly what we do find… in contrast to temperature-related models which should decrease with time away from perihelion.
        CONSERT has also provided evidence that the interior is solid, with no crusts, large voids, or coalesced rubble. The interior of the neck region is static iced, as if torn from a planet… because that’s exactly what happened.

        I’m not saying that the electrical model is absolutely correct and explains what we observe with perfection. What I’m saying is that the dirty snowball model is wrong. Not just kinda wrong that needs to be fixed with more ad hoc hypotheses, but so wrong that the very idea of interior ices or volatiles should be abandoned altogether along with any mention of hypothetical Oort clouds. ANY alternative should be investigated, so long as it can be directly measured.

        Our findings of Rosetta will rewrite history books. Myths and legends of the ancient will be given more credence. Comets were terrifying, catastrophic events which rained fire and oil. No snowball there. The scarring of planets deemed impact craters will be reevaluated. The “cryovolcanoes” of Jupiter and Saturns moons will be acknowledged as ongoing electrical processes.

      • PTR says:

        …are you referring to the giant serpent that ate all the dinosaurs?

    • originalJohn says:

      Good point Ross. These arc discharge crater characteristics have been somewhat overlooked.

    • Graham Hall says:

      I cannot wait for people spouting this baloney about the electric universe in relation to comets to shut up. I would have thought that an electric theory would be supported by actual measurements of the charges, and details of how they are continually formed (so that they can continually discharge). Of course there is no evidence, but unfortunately that doesn’t stop supporters of the theory wasting their own time and that of others here with their nonsense. It a price we have to pay for free speech and expression I suppose, but how I wish that such irrelevances could be screened out of blogs such as this.

  • Bill Harris says:

    This is crop of the ESA Blog Mosaic image of the 10 Jan 15 Navcam, and covers the “D” frame with the “A, B and C” frames on the edges. It has been enhanced to show the interplay of sunlight and shadow on the dust present in the “canyon” of the North Polar Plain as well as sunlight streaming through the dust past the jagged edge of the Major Lobe on the upper right. Note also that the lobe is silhouetted against the faint background glow of the coma in the lower right.

    http://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Dust-Jets/i-w2NtrZw/0/L/Comet_on_10_January_2015_NavCam–enh3–crop1-L.png

    –Bill

  • Robin Sherman says:

    Thanks Claudia. This image gives an excellent chance to spot changes in this region of the neck. It is a very similar view to the October 24th NAVCAM image.

    http://blogs.esa.int/rosetta/2014/10/24/cometwatch-20-october/

    Images D and A of today’s mosaic are the most interesting. Image D includes the former landing site A, Bill’s aptly named “Amphitheatre”, and I am sure he will post one of his nice comparison montages. The changes here are mainly the increase in definition of the “scalloped” areas near the edge of the plateau, the two new circular depressions seen recently and the whole plateau has a more undulating terrain as more of the underlying solid sub-surface shows through. There are now two bright white newly exposed areas of sub-surface along the cliff edge too.

    Below the Amphitheatre, on the neck plain, several new “horseshoe”, or semicircular features can be seen, both in the smoother part of the plain and to the bottom left of the exposed rougher area to the left of them. The cryoboulder that looked like “Yoda” now looks like an Easter Island statue. Towards the bottom of image D the formerly quite smooth plain shows depressions and smaller cryorocks beginning to show through as dust has been removed. The gem though is the two apparent jets coming from the cliff face near the circular features top middle of the image. It is still not possible to see the source here, but those with the right tools might be able to shed more light on that cliff face.

    Image A also has some less noticeable changes, again this is mostly due to the thinning of the dust layer and features of the sub-surface becoming more visible. In the Oct 24th image there is a large lump of cliff that has fallen onto the plain below, pretty recently too, the dusty layer on top is significantly darker than the plain’s dust around it and it matches the surface dust colour at the top of the cliff. In today’s image the change in light exposure has already started to change the appearance of the top surface of this chunk of cliff, it is lighter and some areas have lost almost all their dusty insulation layer to expose the brighter sub-surface underneath.

    Looking at the mosaic as a whole, the terrain is seemingly rougher, more rubble strewn and even more gnarly than it was 10 weeks ago. The effects of the increasing activity are beginning to become visible, not only on the surface, but around it. There are many more white blobs and particles floating around the comet, a few of which would seem to be metre sized and others moving pretty fast, though their distance from Rosetta is unknown so this could be an illusion. The large cloudy blob in image B is a camera effect we have seen on NAVCAM images before, but the number and intensity of jets visible on “normally” exposed NAVCAM images is also increasing.

    • Daniel says:

      I believe you are being fooled by how similar the images are. The view is similar but neither it nor crucially the shadows are exactly the same. You also have a change in resolution to contend with The only surface change I can accept as real is the “horseshoe” features as you call them. Anything else can in my mind be explained away by the change in viewing conditions. Although to be fair, I’m not entirely clear as to which is the “Yoda” boulder for example, so maybe I’m looking at the wrong places.

      Here is a lazily up-scaled and cropped version of the 10th January (montage version) image which you can use to easily compare with the one from 20th October.
      http://i.imgur.com/fNogAIx.jpg

      There is also another NAVCAM image that is from a similar viewpoint (http://blogs.esa.int/rosetta/2014/12/02/cometwatch-30-november/) which I’ve done the same for.
      http://i.imgur.com/z7SdZJq.jpg

      (I scaled/cropped them up simply to make it easier to compare with the 20th October image directly in a browser)

      • Robin Sherman says:

        Hi Daniel. I take your point about the different lighting, phase angle etc. and generally I would have to say there are very few specific visual changes to highlight apart from the crescent shapes in the dust. Even these may only be visible under certain conditions. It is more just a general impression that the thickness and coverage of dust is not the same as a few months ago.

        Thanks to Bill for the enhanced image, however I still can’t really make out the nature of the source of the two jets in Image D. I lean towards it being two exposed cryoboulders, but others interpret it as pits or holes, I am not convinced by either. At least it is evidence of jets emanating from the surface.

        • Daniel says:

          Yeah, there can of course be actual changes visible without them being clear enough to make a definite case for from the in the images we have. Not trying to be too much of a killjoy, just trying to temper the expectations of those that read the comments. The jets also puzzle me, but I assume better pictures (OSIRIS) will answer that eventually.

  • Robin Sherman says:

    Here is an interesting clip from a German documentary about the search for Philae in which we get to get some glimpses of the images which OSIRIS took back in December. Holger Sierks appears in it explaining the difficulty of finding Philae. My German is virtually nil, I got that he talked about overhangs, cliffs and craters, but others here can let us know if he says anything of import.

    https://www.ndr.de/fernsehen/sendungen/hallo_niedersachsen/Was-macht-eigentlich-die-Sonde-Philae,hallonds25212.html

    Pausing and checking the images seen in the video, the spot where I think Philae is hiding is mostly in darkness, but there is one shot with that spot at the centre of a red ring, presumably the CONSERT defined search area, with two bright pixels where I think Philae should be. Now I understand Holger’s reticence about definitely saying they had found Philae. It probably is there, but there is no way to say for definite, from that image anyway. One presumes there are some images that we did not get to see, but looking at the lighting conditions, shadows etc., the phase angle at the time these shots were taken would not permit a positive identification of Philae. The alcove/niche she is hiding in is likely to be in the dark for some time yet from the perspective of Rosetta’s orbit along the terminator. This limits what views the OSIRIS camera can actually get and their lighting. Rosetta’s orbit would have to be over the spot during the comet afternoon and as I understand it the increased activity during daylight hours represents an increased risk to Rosetta from debris and navigation issues due to gas pressure on the solar panels.

    Having made those images public it would be nice if they could be given in the highest resolution available to ESA, so that the world can get a proper look at them and see the challenges faced by the OSIRIS team for ourselves. I don’t think anyone will be able to find Philae, but you never know.

    • Rainer says:

      Hi Robin,

      essentially he talks about the way Philae flew after the first bounce and that it hides somewhere in a stadiumsized field. Temperatures are about -160 °C which is about 100 °C lower than Philae was built for.
      Mr. Goesmann talks about scanning all the data and trying not to fool himself by ‘seeing’ something that might not be there. He has to exclude different things to make sure that his results are as close as possible to the truth.

      • THOMAS says:

        @ Rainer “it hides somewhere in a stadiumsized field”

        The word “field” is perhaps slightly misleading as it suggests something flat. The main point is that Holger Sierks insists, above all, on the extremely rugged nature of the terrain where Philae has chosen to hide away, hence the difficulty in locating it.

        • Robin Sherman says:

          Thanks for the replies. The other thing I could not glean from the pictures was when this interview took place and of course when the images we saw were taken. Like you Thomas I think “field” is slightly misleading, but I guess we can take it in the “field of view” sense. Looks like we are going to have to wait several weeks to have a chance to find Philae, by which time Rosetta will no longer be in these bound orbits of 30Km so it might rely on Philae waking up again and making contact.

  • logan says:

    The solar wind reaches Earth with a velocity typically around 400 km/s, a density of around 5 ions/cm3

    http://en.wikipedia.org/wiki/Aurora

    Flow:

    400Km/s=400,000m/s=40,000,000 cm/s

    At 5 ions/cm3 we have 200,000,000 ions reaching a cm2 each second.

    Taking it to the micro level:

    A cm2=100 mm2=100,000,000 square micrometers.

    So, there are 2 ions hiting a square micrometer of our magnetosphere each second.

    Translating to Ducky:

    Considering average Sun distance to be 3.4 AU. Then 2/3.4^2 ions/square-micrometer=0.17ions/square-micrometer. Or easily spoken:

    One ion impacting a square-micrometer of 67P, each 6 seconds, average.

    Weak magnetism and “jets” probably reducing significantly this flow. Trace atmosphere probably do not.

    There are something between 400 and 8,000 molecules showing in a solid square-micrometer and -chemically speaking- 6 seconds are an eternity.

    • Lucas says:

      Hmm as far as I know flow of charged particles is known as electric current:
      http://en.wikipedia.org/wiki/Electric_current

      Why almost nobody mension this? Everywhere I read I can see “winds”, “rains” or “wawes” of charge or of “hot gas” – why nobody calls it electric current or plasma? If something has 100.000 kelvins its extremaly heated and should be called plasma.

      • Gerald says:

        The solar wind is a plasma. The notion “wind” is maybe not the best.
        Regarding the current, there are electrons, too, such that the plasms is overall electrically neutral.
        I wouldn’t call a driving car an electrical current just because it contains atomic nucei moving relative to the observer.

        Solar wind is a very good conductor, such that it may conduct currents, if there are any differences of electric potential.

      • logan says:

        Hi Lucas, thanks for the reply. If we are going to call it current at the micro level then at graphing it would be a very scattered and discrete line 🙂

    • originalJohn says:

      Logan, you have assumed that the solar current in the heliosphere, popularly called the solar wind, is of uniform density which it is not. The general speed also varies within a range typically of 300-700 km/sec. Usually the density reduces with increased speed. Catastrophic activity such as coronal mass ejections results in increases in both speed and ion density. These effects are however small compared to local effects that can occur in the solar current itself. It consists of a flow of charged particles, ions, and is therefore an electric current and such currents are subject to particular self induced effects. One is the magnetic pinch, known also as the Bennett pinch or a z pinch. This effect, caused by the inward radial force of the induced magnetic field on current filaments, can, in a plasma, result in very large increases in ion current density and one region it occurs in is within the coma of a comet nucleus.

      The positive ions in the solar current are indeed principally protons which are a product of the ionisation of hydrogen atoms, which in the neutral state consist of only 1 proton and 1 electron.

      You can get continuously updated near Earth background proton density and speed data from the SOHO or NOAA space weather websites.

      • Gerald says:

        Calling the solar wind a current is rather misleading, leading to wrong conclusions.
        Calling it a plasma is a good choice.

        • originalJohn says:

          The solar wind, Gerald, is a flow of charged particles. That is all that is required for it to be called an electric current. The plasma provides the ions.

          Not at all misleading. In fact calling it a wind is misleading and obscures the fact that it is an electric current.

      • logan says:

        Hi Originaljohn. Thanks for the guiding me in plasma issues. Does this Bennett pinch or a z pinch applies to mixed flows of both + and – ions?

        • logan says:

          Is solar wind separated in + and – ion ‘hairs?

        • originalJohn says:

          My pleasure Logan.

          Yes indeed the Bennett pinch effect applies to any electric current flow, of positive or negative ions. Normally in the situation we are familiar with, of electricity flowing in metal conductors, the current carriers are electrons, which are mobile in solids, particularly in metals. The pinch in metals is resisted by the atoms which are held in the crystal structure but solid metals can also be deformed by the effect. Interestingly although some electrons in all metals are free to move, they still form part of the metallic bond which is unique to metals. They carry the charge, but are not strictly ions because they are not completely free. If they leave the metal as in electrolysis they become ions in the electrolyte but are immediately replaced in the metal by other electrons from the current circuit, so the neutrality is maintained.

          In a plasma, like the solar wind, both positive ions and electrons are mobile. The general current flow of positive and negative is in opposite directions and at different speeds with the electrons travelling much faster because of their much lower mass. However this is complicated by the fact that electrons can drift for considerable distances in the same direction as the protons.. If there are the same number of protons and electrons in a plasma but acting separately the plasma is known as quasi neutral but has all the properties of a plasma.
          This situation is further complicated in the solar wind by, as you have observed yourself, the presence of other positive and negative ions which are part of the current flow and can under favourable conditions interact with each other. The average density is however low so the distance between ions is quite high and there are also speed differences, so the charge separation is largely maintained.

          The very interesting question about precisely how the opposite electron and proton streams in the solar wind plasma respond to the pinch effect I am afraid I do not know the answer too. If they were confined by the same radial magnetic field they would be compressed in the same pinch I would expect, as both positive and negative constitute the overall current flow. In this way the positive flow could be pinched by the negative flow and vice versa.
          I am not aware of any work on this issue but I would imagine that it has been looked at in the fusion research field.. They are however using a much simpler plasma than the heliosphere plasma.

  • logan says:

    Could’nt find anything about this:

    Does solar wind speed refer only to proton speed?

    If that speed apply to all particles then they arrive with very different energies.

  • logan says:

    Hi Claudia. This particular lighting on the lower left lobe shows what to me appears as a polyhedral quality on the shape of 67P.

  • logan says:

    Right now I am back to the electromagnetic spectra as the main energy source. Maybe those undusted surphaces are not opaque, maybe those are an ‘optic trap’.

    • logan says:

      Looking directly at those undusted surphaces would be like looking down into the abism 😉

  • Guili says:

    Feels a bit like a joke that we mostly get OSIRIS news from Mr Sierks interviews in german medias instead of the ESA channel/blog…

  • THOMAS says:

    @ Steve Kasian

    Great observation!

    It should be noted above all, given the scale of the image, that very close to their point of origin both jets must be several metres in diameter. This single image thus conclusively refutes the theory of the millimetre-sized “nozzles” which were always required by the standard theory (combined with high temperature/pressure of the supposedly subliming ice…) to give any plausibility to its explanations in terms of standard fluid mechanics for the observed 700 m/sec velocity of the material making up the jets.

    No need even to do the maths, so clear is the prima facie, ocular evidence. There is no way these can be jets of subliming ice, particularly since they are leaving an area which is clearly a rock face.

    • Sovereign Slave says:

      Took me awhile to find the jets, but sure enough, there they are, and they do look quite big at the base, which is not possible for the proposed method of jet formation through sublimation. Another oddity is that the jets originate in shadow, where the temperature is much less than in the sunlight. If the jets were due to sublimation and subsurface ice was prevalent and more or less evenly distributed under the surface, seems the jet patterns should always be strongest in sunlit areas and completely stop as they go into shadow. If surface ice isn’t sublimating in shadowed craters on the moon and Mercury, subsurface ice should definitely not be explosively sublimating in shadow on P67.

  • Harvey says:

    Normally my posts are short; hopefully I can be permitted a longer one as this will be my final post on the subject, barring exceptional new observations by Rosetta. I will not post references in this for brevity; my previous posts contain many.

    As Rosetta approached 67P I was vaguely aware of the ‘dirty snowball’ theory, but hold no ‘allegiance’ to it whatever. I soon became aware of an alternative theory, which I will paraphrase as the ‘EU’ theory (though that is wider.) So, interesting, I went & looked it up. It would not ‘upset me’ if the EU model was correct, I have nothing ‘invested in it’ & I’m quite happy to admit when I’m wrong. I am, obviously, a ‘conventional scientist/engineer’ – who has worked extensively on discharges, high voltages, vacuum systems, cryogenics, spectroscopy etc – & a little on spacecraft – so I do know something of this.

    The principle site is the ‘Thunderbolts Project’, very slick & glossy. It did not impress me. A great deal of regurgitated textbook physics, almost no numbers, and no coherent development of a real ‘theory’ at all. Images of things which formed *under oil*, on a micron scale, are compared to multi-km scale images, formed in vacuum. Others, highly selected, of a fused grain which happens to look like 67P; you could equally have used a peanut & claimed 67P is obviously a legume frankly. It happens that some of the talks at the 2014 conference are directly in my field of expertise, so I watched them. They are FULL of obvious, gross errors. The related papers contain blatant mathematical errors, & are in a Journal which clearly does not referee properly; all papers accepted in a day or two. I did not get off to a good start with EU ‘theory’.

    To rather brutally paraphrase these two theories
    – Conventional, ‘C’, holds that comets contain water & other ices mixed with rock & dust; they warm up & sublime as they approach the sun, forming the coma. Large body of detailed, refereed papers.
    – The ‘EU’ – ‘theory’, as expressed here, asserts that there is no ice; the comet is (solid, in some views) rock; the water is formed by sputtering from the solar wind, and surface features are formed by ‘electric discharge machining’. Essentially no detailed, refereed papers.

    ‘Refereed papers’ are viewed by the EU community as the stuck-in-the-mud conventional view where nothing radical will ever surface. All I can say is that as a Journal Editor in Chief, frequent reviewer, & frequent writer of papers, that is a parody. The refereeing process exists to remove errors, ensure novelty, etc; no editor worth anything rejects ‘because it’s too novel’ – & if they did, there are plenty of other Journals. Being original is how you make your career. Fifty years ago there was some justification for the EU view of refereeing, Journals; long gone.

    What does the evidence have to say? C++, strongly supports ‘conventional, C+, C, EU/C (deuce), EU, EU+, EU++ scale, obviously my subjective view.

    1. Topography. The topography of 67P is bizarre. C has no real explanation of it; EU purports to, but actually has no real explanations other than vague visual similarities to things formed in utterly different circumstances which are invalid. Deuce C/EU

    2. No ice is seen on the surface – much is made of this by the EU community. It’s perhaps a bit surprising it’s so hard to see; but ablation will concentrate refractory materials on the surface, & it only takes a micron of black gunk to hide the ice. So for C, bit of a surprise, but not a big problem. Deuce C/EU perhaps. Might give EU a small edge.

    3. Density. The density is ~0.4g/cc as determined by the gravitational interaction with Rosetta, ESA could not conceivably navigate round 67P if this was badly wrong. It is broadly consistent with other comets. Completely inconsistent with solid rock. Could be consistent with a very high pore volume rock composite, or a considerably lower pore volume ice/dust/void composite. Deuce EU/C for composite models, maybe leaning to C. But C+++ if the ‘opposition’ is solid rock.

    4. Water emission. MIRO & previous measurements on other comets directly observe large amounts of neutral water, H2O molecules. There is no physical mechanism to form these by solar wind sputtering, you will get protons, O, O+, a little OH etc, virtually no H2O. Proton sputtering has a very low yield & must depend on sputtering previously implanted protons. C++

    5. The amount of water VASTLY exceeds the proton supply from the solar wind over the comet projected area & the disparity worsens a 67P approaches the sun. EU argues a plasma ‘pinch’ concentrates the solar wind on 67P – no detailed model of how/why. But there would be a magnetic field & plasma signature of that; none observed. If purely protons strike the comet (why?) it will charge up & repel the protons; if it self- neutralises with electrons, as expected, there is no net current, so no magnetic field to cause a pinch. C++

    6. If it is sputtering off huge amounts of oxygen, it will have to sputter off comparable amounts of silicon etc. But no very strong silicon signature is reported in the spectra, C+

    7. Glow discharges & arcs produce obvious spectral signatures from electronically excited atoms & ions. What emission is seen is consistent with solar UV photodissociation & photo ionisation; it is not consistent with an arc or glow discharge. C++

    8. The solar wind density will simply scale as reciprocal distance to the sun squared; but comet activity varies *MUCH* more strongly than that, consistent with the much more nonlinear variation of vapour pressure with temperature. Furthermore, the comet’s bow shock structure – the basis of which is theoretically well understood & the shock directly observed on other comets – will partially shield 67P from the solar wind, but not from thermal flux. C+

    9. ROSINA reports a very high D/H ratio; the solar wind is depleted in D & has a low D/H ratio, so cannot be the source of the ROSINA water. C++

    10. Limited data from the ROSETTA RPG plasma experiments supports a conventional photoionised plasma model. C, C+

    10. CONSERT data. Very limited so far. On a few paths supports a rather uniform
    fine-grained structure consistent with EU & C ‘composites’ is reported. HOWEVER, the delays would be wildly different for a ‘solid rock’ model, but these have not been reported. Unless the CONSERT team are deliberately hiding data in conflict with the 0.4 density – which I do not believe – also rules out solid rock. Could be consistent with either ‘composite’ model. EU/C deuce for composites, leaning to C; probably C+ for solid rock, but not proven yet.

    11. Only comets produce large water molecule bearing comas. Rocky bodies, our moon (closer to the sun than 67P), asteroids, do not – but are also exposed to the solar wind. No EU explanation for the difference I have seen; conventionally, comets contain water ice, the others don’t. C++

    Enough. The conclusion is blindingly obvious. The discussion of EU v C here & elsewhere does not have the character of a rational scientific exchange; it is far closer to a ‘religious’ matter. If data disagrees with the EU, it simply ‘must be wrong’ (the density is an example par excellence) or it just gets ignored. The EU community spends its efforts trying to disparage the C community, as opposed to developing rational, coherent theories which agree with the observed data. Much depends on what is ‘obvious’ visually; but this is a *very* dangerous route for C or EU; the environment of 67P, hard vacuum, low gravity, periodically heated, exposed to solar wind & hard UV etc, is so outside normal experience common sense, intuition, what is ‘obvious’ is likely to be wrong.

    So there is no point in continuing the exchange really, I will leave ‘EU theorists’ to their parallel electric universe  where any observation always supports that view, & proper detailed models, maths are not required.

    • Marco says:

      Good. Now that you have cleared the decks from what is clearly a quasi-religious false dichotomy, you can concentrate on the main game for citizen scientists and armchair astronomers. That is, stretch vs. ablation vs. contact binary vs. “something we haven’t thought of which is not a combination of these” debate, as to what causes this and other bilobed shapes in comet nucleii. I am lumping “machining” with sublimation as different methods of ablation.

    • originalJohn says:

      Harvey, I first posted this reply a week ago and it has yet to change from awaiting moderation. So here is another try in slightly modified form. Lets skim through your points list one by one and see it for what it is.
      Thunderbolts Project is not aimed at you it is aimed at the people and is not in the business of garnering academic kudos. Regurgitating text books? Isn’t that what the academic world is all about , or do you see yourselves as pioneers. And the fact that plasma effects are scalable and measurable from a few centimetres on the laboratory bench to to kilometres in interplanetary space has enormous significance, which you have yet to come to grips with. It is far from contradictory.
      I bow to your specialised knowledge of black bodies and Kirchoff’s Law but why don’t you then confront the scientist concerned. Maybe he would find fault with some of your work.
      No such thing as EU theory. It is a paradigm for cosmology of which the comet mechanism is a part and it is multidisciplinary. No ice is not an assertion, it is an observation that you can only contradict with a hope.
      As for refereeing, you would say that, wouldn’t you.
      Your rating system is a measure of how much you are convinced either way. Purely personal. Means nothing.
      The topography is only bizarre if you were not expecting it. It is actually specific. There are detailed explanations which you have not encountered.
      No ice. Inescapable.
      For other comets cited mass was estimated based on the snowball idea, The measured mass of this one is an anomaly. If you can’t see that you never will. Navigation not significant. Gravity works. Such a huge mass difference between the craft and planets that errors would be minute and adjustable by feedback.
      The water formation thing is your opinion. You don’t know what is possible in the coma environment. And if no ice, where does the water come from. And you only know about sputtering “yield” in laboratory equipment.

      The proton deficiency, on results so far, I have shown is of the order of 10 power 5. Easily attainable in a plasma pinch. Not EU argument. My argument.
      No model needed. It is a behaviour of plasma recognised in plasma physics. Any way almost impossible to model plasma. How do you know what has not been observed and whether it has been looked for. It is discharging all the time but is a prolific source of electrons, so gradually. And it may as I have speculated achieve neutrality temporarily near or just round the Sun. Other comets have.

      No strong silicon yet? How do you know. There is loads of dust. What filters have been used.
      7. You know all the results so far do you?

      The average density may be reciprocal squared but it is not uniform, it is non linear as you require The bow shock concept is a model and an invalid one.

      High D/H on one occasion. D/H not fixed anyway, D/H varies throughout solar system bodies, yet all came from the Sun disc, supposedly. More data needed.

      Hardly any data yet from plasma experiments.
      Hardly any CONSERT data yet.

      The coma is a current density/plasma effect peculiar to comets because of highly elliptical orbit and resultant charge imbalance. Planets have almost circular, charge stabilized orbits and much lower discharge. Some water still forms. Some asteroids have coma and tail.

      Sorry Harvey, the standard comet theory is the religion. The EU paradigm is an open, objective approach trying to reach the truth. No attempt to disparage by EU people, Just highlighting of aspects which contradict observation or for which no evidence exists. That is science. The attempted disparaging comes from certain mainstream individuals. A lot depends on it for them.

      You are right. It is pointless to keep grinding this out. Lets see what happens. We have nailed our colours to the mast.

  • Harvey says:

    Oh, for completeness, as its another ‘deuce’ & live topic.

    How are the gas jets formed?
    Of course we arent seeing the gas jet, just the dust; beware.
    And the gas dynamics, expansion into space, probably with a nozzle shock wave, from a very low pressure source, is unlike anything we are used to. Dust particles will rapidly just continue on their free trajectory.
    C struggles to explain them certainly, though it doesnt look ‘impossible’ its weird. But EU just claims they are ‘obviously’ electrical; no detailed model of course. How does it accelerate mainly neutral gas? Why do they look as they do? It has no better explanation than C.

    Both are in some difficulty here; deuce.

    • graham Hall says:

      Harvey a well argued and fair comparison of the opposing theories. But on the gas jets there is published material on a model which, while not definitive, gives a sound basis for further work,
      http://www.lpl.arizona.edu/~yelle/eprints/Yelle04a.pdf

      I’d wager the Rosetta scientists are busy writing their own papers along these lines right now. C+?

    • originalJohn says:

      Harvey, the origin of the speed and trajectory of the dust particles would be the gas jet. What force would cause the two to deviate.
      No model is required for a straightforward electrical discharge. Nobody models lightning. It is protons in, negative ions out and jets with typical plasma characteristics. They have yet to be positively identified as ionized or neutral, unless you have exclusive knowledge.

      • Harvey says:

        ‘No models required’ is the entire problem. OF COURSE they are required. Discharges of all types are extensively modeled – including arcs – as is the plasma environment of comets. ‘Typical plasma characteristics’ is completely meaningless; the properties range hugely; but the vast majority emit telltale visible light (GLOW discharges, ‘arc eye’..) which we do not see. Most such discharges have low ionization fractions; only the ions get accelerated, not the neutrals. Neither do we see the magnetic fields associated with a pinch; which couldn’t be formed & simultaneously solve the charging problems.
        So now its negative ions; typically fragile things, with low binding energies for species like H-, O-. – not that they solve the problem.
        These things are just ‘thrown out’ as if they magically solve it; no observation to support it, no model to show they could form, & frankly clearly no understanding.

  • logan says:

    Harvey, fully sorrow if we are causing despair around. In the short term, things are going to (un)settle down mostly as you predict on your 13 points(there are 2 ten plus an addend).

    As you said, you are done on EU. I am being exposed to it here for the first time. And I wouldn’t, if not for Rosetta’s blog. Here I have the privilege to take a look at it, in a critical and guided way. Quite surely I would not find a lot of dissent about thunders and volts at ThunderVolts.com.

    Even conservative thinking about small planetary bodies is accepting the relative relevance of the other two field forces. So, why not begin to talk seriously about those?

    Hard Numbers from the Teams could contribute to consolidation of perspectives in a lesser an more manageable number [and to shut up my mouth].

    Got that, Marco 🙂

    • Kamal Lodaya says:

      Logan: I see your point, I also encountered EU for the first time on this blog. Since Philae is sitting there, if it wakes up, can one think of an experimental measurement which will bear upon this issue? I personally don’t see the viewpoint that everybody else has to be wrong. For example, why can’t one have sublimation and sputtering both happening at some relative ratio dictated by the numbers? On the numbers, Gerald has a calculation on the “Fine structure” post.

  • Prof Harvey Rutt says:

    Capta ate it? Second try.
    Graham
    Thanks for the reference, as its a properly worked through version of my back of the envelope version elsewhere and above, of course I like it 🙂
    Yes, C at least maybe C+ as you suggest.

    BTW I intend to remain involved in sensible discussions. I’m just not going to bother refuting EU dogma.
    I do scientific discussion, not religious conversion.

    • originalJohn says:

      Lets have a proper scientific discussion then Harvey. Lets talk about the water being emitted by the comet nucleus, from beneath the surface. Of course as scientists we would definitely have positive evidence of a source of water within the nucleus before we believed that was where it was coming from. What, we have no evidence at all, But lots of people say that there is ice there and have been saying it for a long time so it must be true. So we will assume that it is there. Now we can base all our subsequent conclusions about what is in the coma on that belief. And we do have positive evidence that the jets coming from the nucleus are neutral molecules and nothing else. What, we don’t have positive evidence of that either. Well never mind, we will assume it is true. Lots of people say it is so it must be, and there is water in the coma after all. So thats it settled then. There is ice in the nucleus, sublimating as neutral molecules into the coma. We are really beginning to find things out now. Proper science. That’s the way to do it.

      • Harvey says:

        I have zero interest in ‘what people say’; I’m interested in *the evidence*.
        We have known for over thirty years at least that comets emit vast amounts of neutral water vapor; for Halley, some 5100kg/s, not even at perihelion.
        http://www.ncbi.nlm.nih.gov/pubmed/17773501
        This is simply ignored. There is no remotely credible source of that other than ice in the comet body.
        Claims to the contrary simply do not accord with basic physics or observational evidence for umpteen separate reasons. The equivalent ‘proton current’ would be ~54GA. Yes, *G*A.
        I can’t be bothered to keep trying to teach physics 101 to those with no interest in it, or argue with those who ignore the evidence. It’s a complete waste of time. Its quite clear that no scientific discussion is possible.

        • THOMAS says:

          Harvey, if you had wanted to prove the precise point that Originaljohn is making, you couldn’t have done it better.

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