Ultraviolet study reveals surprises in comet coma

This news item is mirrored from the main ESA web portal.

Rosetta’s continued close study of Comet 67P/Churyumov–Gerasimenko has revealed an unexpected process at work, causing the rapid breakup of water and carbon dioxide molecules spewing from the comet’s surface.

ESA_Rosetta_Alice_Infographic150602

ESA’s Rosetta mission arrived at the comet in August last year. Since then, it has been orbiting or flying past the comet at distances from as far as several hundred kilometres down to as little as 8 km. While doing so, it has been collecting data on every aspect of the comet’s environment with its suite of 11 science instruments.

One instrument, the Alice spectrograph provided by NASA, has been examining the chemical composition of the comet’s atmosphere, or coma, at far-ultraviolet wavelengths.

At these wavelengths, Alice allows scientists to detect some of the most abundant elements in the Universe such as hydrogen, oxygen, carbon and nitrogen. The spectrograph splits the comet’s light into its various colours – its spectrum – from which scientists can identify the chemical composition of the coma gases.

In a paper accepted for publication in the journal Astronomy and Astrophysics, scientists report the detections made by Alice from Rosetta’s first four months at the comet, when the spacecraft was between 10 km and 80 km from the centre of the comet nucleus.

For this study, the team focused on the nature of ‘plumes’ of water and carbon dioxide gas erupting from the comet’s surface, triggered by the warmth of the Sun. To do so, they looked at the emission from hydrogen and oxygen atoms resulting from broken water molecules, and similarly carbon atoms from carbon dioxide molecules, close to the comet nucleus.

They discovered that the molecules seem to be broken up in a two-step process.

First, an ultraviolet photon from the Sun hits a water molecule in the comet’s coma and ionises it, knocking out an energetic electron. This electron then hits another water molecule in the coma, breaking it apart into two hydrogen atoms and one oxygen, and energising them in the process. These atoms then emit ultraviolet light that is detected at characteristic wavelengths by Alice.

Similarly, it is the impact of an electron with a carbon dioxide molecule that results in its break-up into atoms and the observed carbon emissions.

“Analysis of the relative intensities of observed atomic emissions allows us to determine that we are directly observing the ‘parent’ molecules that are being broken up by electrons in the immediate vicinity, about 1 km, of the comet’s nucleus where they are being produced,” says Paul Feldman, professor of physics and astronomy at the Johns Hopkins University in Baltimore, and lead author of the paper discussing the results.

By comparison, from Earth or from Earth-orbiting space observatories such as the Hubble Space Telescope, the atomic constituents of comets can only be seen after their parent molecules, such as water and carbon dioxide, have been broken up by sunlight, hundreds to thousands of kilometres away from the nucleus of the comet.

“The discovery we’re reporting is quite unexpected,” says Alice Principal Investigator Alan Stern, an associate vice president in the Space Science and Engineering Division of the Southwest Research Institute (SwRI).

“It shows us the value of going to comets to observe them up close, since this discovery simply could not have been made from Earth or Earth orbit with any existing or planned observatory. And, it is fundamentally transforming our knowledge of comets.”

“By looking at the emission from hydrogen and oxygen atoms broken from the water molecules, we also can actually trace the location and structure of water plumes from the surface of the comet,” adds co-author Joel Parker, an assistant director in SwRI’s Space Science and Engineering Division in Boulder, Colorado.

The team likens the break-up of the molecules to the process that has been proposed for the plumes on Jupiter’s icy moon Europa, except that the electrons at the comet are produced by solar photons, while the electrons at Europa come from Jupiter’s magnetosphere.

The results from Alice are supported by data obtained by other Rosetta instruments, in particular MIRO, ROSINA and VIRTIS, which are able to study the abundance of different coma constituents and their variation over time, and particle detecting instruments like RPC-IES.

“These early results from Alice demonstrate how important it is to study a comet at different wavelengths and with different techniques, in order to probe various aspects of the comet environment,” says ESA’s Rosetta project scientist Matt Taylor.

“We’re actively watching how the comet evolves as it moves closer to the Sun along its orbit towards perihelion in August, seeing how the plumes become more active due to solar heating, and studying the effects of the comet’s interaction with the solar wind.”

More information

“Measurements of the near-nucleus coma of Comet 67P/Churyumov-Gerasimenko with the Alice far-ultraviolet spectrograph on Rosetta,” by P Feldman et al is accepted for publication in Astronomy and Astrophysics. The paper is available to read online, here: http://www.aanda.org/10.1051/0004-6361/201525925

 

Comments

96 Comments

  • masanori says:

    Excellent job Rosetta & the Alice team!! Not only Alice but I am so impressed and delighted by all the instruments on both Rosetta and Philae for working seemingly in excellent condition after all these years of travelling through Solar System, at the place where the team have wanted them to work properly. All of them should. But this is the most important, I think, and the reason why I applaud for this mission with huge respects. Some might say it’s too early to say this but I strongly feel this very long planning & travelling already paid off!!

  • Gerald says:

    It’s a big pleasure to see the cream of the crop working together in such a productive way!

    Despite being “just” an initial paper, we are already getting a much deeper insight into the processes in the close environment of the nucleus.

  • dave says:

    Glowing Paper,
    great detective work, was a pleasure to read, well done to the whole team.

  • J.H. says:

    That process is Photoelectric…. is it not? A Photon energizing something into releasing an electron?

    • Harvey says:

      Photoionisation is the term usually used.
      The ‘photoelectric effect’ is usually applied to photon induced electron emission from a solid surface,.
      There is considerable similarity, but in the first case you can identify a specific positive ion, whereas in the latter you usually cannot, certainly if the solid is conducting, as there is a ‘sea’ of electrons in the solid.

      • J.H. says:

        But there would appear to be a “surface”… at about a kilometre from the comet nucleus…. It is there that the electrons are electrolysing oxygen and hydrogen from water…. Thus there is a “current” there.

        That’s what is going on here isn’t it?

  • ianw16 says:

    Hmmm, I suppose all this H20 and CO2 is coming from sublimated ices. No surprise there for most of us. It’d be interesting to know how the EU proponents explain this, given that they think its rock. Based on what I’ve seen elsewhere, I suspect they’ll invoke O ions being stripped from the comet, then combining with protons from the solar wind to form OH and H2O. So before that argument is made, there are 7 orders of magnitude too few protons in the solar wind to account for the measured amount of water, as reported some months ago when 67P was at 2.7 AU and producing, on average 1 litre of water per second.
    I know they don’t like maths, but;
    average proton density in solar wind at 1 AU ~7 protons cm^3. Declines with inverse square law. So at 2.7 AU ~ 1 proton cm^3. Average velocity of solar wind ~400 km/s. Area of 67P facing solar wind? Generously let’s say 4 x 3 km = 12 km^2. Converting to cm, the number of protons impacting 67P is (4.0 x 10^7) x (1.2 x 10^11) = 4.8 x 10^18/s.
    Number of molecules in 1 litre of water? 3.3 x 10^25!

    • Gerald says:

      They invent a z-pinch to fill in the seven orders of magnitude. This would of course immediately destroy Rosetta, contradict all measurements, and it lacks any physical mechanism. To overcome the lack of physical mechanisms they invent huge charges to cause strong electrical fields. Again hugely contradicting abundant measurements, and basic physical principles, like repulsive Coulomb forces which would disrupt the comet, and conservation of electric charge.
      To resolve this, they invent a chemical perpetuum mobile combusting organic material of the comet with strongly bound oxygen from silicates.
      To resolve this, math and physics must be a big conspiracy of the establishment, for the electric universe people. Otherwise electric universe ideas would be buzz-wrong, which cannot, must-not, argh, … 😉

      • THOMAS says:

        Actually, Gerald, it was Nature itself which “invented” the Z-pinch effect some time before the EU/plasma cosmology people got round to start talking about it (a few billion years earlier at least, depending on how old you think the Universe is) (see http://en.wikipedia.org/wiki/Pinch_%28plasma_physics%29).

        The EU/plasma cosmology people simply made the discovery that the Z-pinch effect is a universal mechanism whereby the electromagnetic force, acting via Birkland currents flowing through dusty plasma (i.e. the whole of inter-stellar and inter-galactic “space”), shapes and drives all the most clearly-visible objects in the universe (and probably most of the less visible ones too). Hundreds of images acquired by the Hubble space telescope have since provided ample evidence of the fact, the most emblematic no doubt being the beautiful neon-tube-shaped “planetary nebula” M2-9, also known as the “Twin Jet Nebula” or the “Butterfly Nebula”: http://upload.wikimedia.org/wikipedia/commons/f/f1/Planetary_Nebula_M2-9.jpg

        The Wikipedia article “Bipolar nebula” (http://en.wikipedia.org/wiki/Bipolar_nebula) states that “A bipolar nebula is a distinctive nebular formation characterized by an axially symmetric bi-lobed appearance. Many, but not all, planetary nebulae exhibit an observed bipolar structure” before admitting (as usual in these cases where the only reference-frame and the only toolbox available are those of standard theory gas kinetics rather than those of plasma cosmology) “the exact causes of this nebular structure are not known”. That says it all…

        Another image used to illustrate the article, that of PN Hb12, (http://en.wikipedia.org/wiki/Bipolar_nebula#/media/File:Bipolar_planetary_nebula_PN_Hb_12.jpg) displays the ubiquitous hour-glass shape which is also to be seen in such apparently disparate objects as the supergiant star Eta Carina (http://en.wikipedia.org/wiki/Eta_Carinae#/media/File:Eta_Carinae.jpg) and the supernova SN 1987A (http://www.holoscience.com/wp/supernova-1987a-decoded-2/)

        Come to think of it, 67P itself, with its own roughly hourglass shape and its “jets” emanating mainly from the neck region (look at the Eta Carina image again) and now, increasingly, along the longitudinal axis, exhibits the same sort of properties, doesn’t it? Given the increasing charge difference between themselves and the Sun as they approach it, comets are indeed the focus of modest Z-pinches in those parts of the solar wind which they are traversing.

        • Gerald says:

          THOMAS, what are you trying to say? That hourglasses and yoyos are electrical discharges?

          Eta Carinae is a rather instable giant star, an interesting object
          http://en.wikipedia.org/wiki/Eta_Carinae

          It will probably undergo a supernova explosion in the (geologically) near future:
          http://en.wikipedia.org/wiki/Supernova
          Somewhat similar to SN1987A:
          http://en.wikipedia.org/wiki/SN_1987A

          The explosion remnants can take the “bipolar” shape similar to hourglasses.

          But this doesn’t have anything to do with hollow-worlders of flatlanders.
          Some people write about fantasy worlds in their spare time for amusement. And obviously there are people who take this for real – no it isn’t, that hollow world stuff is just entertainment.

          • THOMAS says:

            @ Gerald
            “THOMAS, what are you trying to say? That hourglasses and yoyos are electrical discharges?”

            Sorry for again having to state the obvious but, with all due respect, your comparison is invalid. Hourglasses and yoyos are man-made artifacts, whereas the multitude of “hourglass-SHAPED” objects already observed at every scale in the Universe have been so shaped by the fundamental universal driving bi-polar force which you believe to be “gravity” (whatever that is…) and which I believe to be “electricity” (that tiny difference between a -sign and a +sign…). That’s the difference between a man-made artifact and objects formed by Nature itself: we have all drawn naïve pictures of the Sun as children but none of our pictures have ever given off anything like the heat (not to speak of the electromagnetic radiation…) which the Sun itself does.

            Speaking about the SN1987A supernova event, you say: “The explosion remnants can take the “bipolar” shape similar to hourglasses.” Sorry to have to differ again, but it’s not that the remnants “can” assume an hour-glass shape but they actually HAVE done so. The difference between us is that the model I favour explains (and actually predict) this bi-polar shape (that’s how electricity self-organizes, complete with Z-pinch effects…) whereas your standard model has absolutely no explanation for it (gravity just doesn’t do that sort of thing, does it?).

            I’ve no idea what your “hollow world stuff” refers to…

          • Gerald says:

            THOMAS, the crab nebula is another supernova remnant:
            http://en.wikipedia.org/wiki/Crab_Nebula
            Where is your predicted bipolar shape?

            Electromagnetism is one of the four (known) fundamental forces of the standard model of particle physics. As the other three forces, gravity, weak and strong nuclear force, you can find it everywhere in the universe, if you just look and measure sufficiently accurate.
            http://en.wikipedia.org/wiki/Standard_Model
            In supernova explosions all four fundamental forces are involved significantly.
            Your z-pinch doen’t explain much of anything happening in supernova explosions, their remnants, nor does it relate to the shaping of comets.
            A splash of water has to do more with the shape of supernova remnants than a z-pinch:
            https://www.youtube.com/watch?v=axOcr15TV_M

          • Gerald says:

            THOMAS, sorry I thought you’ve been referencing a hollow world website, but the referenced “holo” site is even worse, actually it’s beyond my pain tolerance.

            In comparison more reasonable fictive worlds:

            Hollow earth:
            http://en.wikipedia.org/wiki/Hollow_Earth

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

      • Harvey says:

        Ianw16 – be warned, Gerald, I and one or two others have been combatting this nonsense for months. It’s impossible to ‘win’ because proper scientific argument is irrelevant. They know they are right!

        If you want a real laugh (or possibly apoplexy) take a look at the Thunderbolts web site. It’s a logic, evidence, physics and number free zone, but unquestionably (in the literal sense of the word) explains life, the universe and everything – including of course comets.

        • THOMAS says:

          Harvey, please allow me to take mild issue with your renewed attack on anything which doesn’t fit into your tidy little tool-box, especially regarding the notions of “logic, evidence and physics” which you appeal to.

          Regarding the considerable body of evidence which Rosetta has already garnered and which is plain for all to see (bearing in mind that what has so far been disclosed is just a tiny fraction of the images and data which have been actually acquired, especially in view of the increasingly intriguing non-disclosure of the long-awaited OSIRIS images), please read the (non-exhaustive) list of totally “surprising” and/or “unexpected” features, facts and figures in my post above (http://blogs.esa.int/rosetta/2015/06/02/ultraviolet-study-reveals-surprises-in-comet-coma/#comment-466773). The “logic” which these hard facts show in refuting the standard “dirty snowball”/”icy dirtball” theory is absolute and implacable.

          As for having “a real laugh (or possibly apoplexy”), you presumably know the old English saying which begins “He who laughs last, laughs…” Comet 67P is now just 2 months from perihelion with, for example, consistent evidence of a preferential axial location of the jets (firstly orthogonal to the longitudinal axis, from the neck region, and now increasingly in the longitudinal axis itself), clearly suggestive of electrical circuitry; once the complete data-set (including the full set of OSIRIS images) has been disclosed and analyzed, we will see who laughs longest.

          • Harvey says:

            I’ll very, very happily take that risk!
            So far, there is *not one single item* of quantitative evidence in support, and. A VAST mass of evidence opposing, the assertion that the jets are discharges.

            I’ve been asking for it since forever and never had an answer; how does the ‘discharge circuit’ work?
            ‘Charged comet discharging’ is quantitatively utterly ludicrous, and why hasn’t it discharged?
            Anything else seems to require a conducting comet which magically is an anode and a cathode at the same time.
            So please, baby steps for an idiot to understand, preferably with some numbers, *how does the ‘circuit’ work*?

          • Kamal Lodaya says:

            Thomas: Like Harvey I am puzzled why you think “consistent evidence of a preferential axial location of the jets” is “clearly suggestive of electrical circuitry”. Which axis? Not the rotational one which you said some time ago had a very slow 12 hour period. Why should any other line drawn by our imagination have anything to do with electricity? I think you are also wrong on the facts: there is no preferential axial location of the jets. The pictures we have seen in recent months show jets in all directions, preferentially more in the daylight half towards the zenith.

          • THOMAS says:

            @ Harvey
            “So please, baby steps for an idiot to understand, preferably with some numbers, *how does the ‘circuit’ work*?”

            Harvey, perhaps the first “baby steps for an idiot to understand” should be taken by first examining the most spectacular form of discharge phenomenon which we are all familiar with in our own backyard down here on Earth, which we call “lightning”. Take a look at this example: http://www.abc.net.au/news/image/4400182-3×2-940×627.jpg, then tell me whether you are able to explain the circuitry (preferably with numbers, of course).

            Once you’ve done that and if it seemed too easy for you, by all means go on to the next step (for merely stupid people), which is to explain (preferably with numbers) the circuitry involved in other, rarer manifestations of terrestrial lightning which the scientists call “upper atmospheric lightning” (“red sprites”, “blue jets”, elves” etc.) shown schematically here: http://en.wikipedia.org/wiki/File:Upperatmoslight1.jpg in the Wikipedia article: http://en.wikipedia.org/wiki/Upper-atmospheric_lightning.

            Once we’ve got these “baby steps for idiots” out of the way and finally arrived at a satisfactory level of understanding of these discharge phenomena occurring in our own back yard (which is, to date, very far from being the case), we might at last get round to venturing tentatively out into the plasma-filled space contained within the heliosphere and start to try understanding the circuitry (and numbers) involved in electric discharge phenomena affecting other bodies in the Solar System such as comets (but also the moons of Jupiter and Saturn, among others…). For the moment, we have only obtained direct observations of some of them, including comet 67P, so any demands for the description of the precise circuitry involved (with numbers…) would seem a little premature. Use your standard theory toolbox, Harvey, to first try explain to us the precise nature of the discharge phenomena taking place hundreds of thousands of times every day down here on Earth.

          • Kamal Lodaya says:

            Thomas: I didn’t understand your explanation of circuitry. Is there some axis on Earth which is an underlying cause of lightning?
            Kamal

          • Harvey says:

            As ever, a completely content free ‘explanation’, just irrelevant comparisons. Lightening, a high pressure pulsed small area discharge, is utterly irrelevant. As is whether I have numbers for it (they are readily available on the web.)
            Instead of actually explaining 67P you simply try to distract.

            FOR THIS COMET how does it work?

            There have been repeated claims its negatively charged. What is the charge, the voltage, the discharge current? Just rough order of magnitude values are fine.

            If it’s not charged, but part of some circuit, just how does it work? Where are the electrons coming from, going to, on the comets surface?
            What order of magnitude of current are we talking about? How does the comet avoid charging/discharging?
            Is it conducting or insulating?
            What order of magnitude is the discharge current density?

            Nothing ‘precise’, just a broad, rough description with some rough order of magnitude numbers.

            If you have no answers to these questions, you don’t have the beginnings of a model or a prediction. Whether I or anybody else has an explanation of some unrelated, or even related, phenomena does not change the absense of an explanation for this supposed discharge.

          • Gerald says:

            THOMAS, I’ve no problem at all with understanding the lightnings on Earth, including the involved circuits, at least on a basic level.

            But actually you didn’t explain anything, not even rather well-understood lightnings on Earth, but just tried to escape obviously indissoluble problems with your electric discharge mis-interpretations of the cometary activity, even on the most basic level, applying more-than-poor rhetoric. So please try it again, the version you provided above is more than disappointing, even for electric universe circumstances.

          • Sovereign Slave says:

            To Harvey, Gerald and company, not to speak for Thomas, but I think it’s obvious that he’s making the point that the phenomena of electricity, especially as it exists in nature, is really not well understood at all, can be very hard to make sense of, is difficult to measure, model, math, and define in all its manifestations, and is only known to exist in some instances based on observation alone, such as sprites, though there are no real explanations behind that knowledge. Case in point, for years and years it’s been believed by the scientific establishment, and presented as fact, that lightening is created as a result of clouds that generate positive and negative charges to the point of discharge, and this is still what is found as the common explanation. But there is research suggesting that lightning is actually triggered by cosmic rays (linked below). Where those rays might come from I think is an open question, but at any rate, I think it’s obvious that modern science is just scratching the surface of what electricity in nature, and the cosmos, is all about, and what it’s capable of, and that there’s much much more that’s unknown about it than is known, despite the protestations of those who seem to think they have the scientific high ground in this and all other matters related to P67.

            Anyway, here’s the link:

            http://www.pbs.org/wgbh/nova/earth/lightning.html

          • Gerald says:

            Sovereign Slave, the point is, that lightnings on Earth are consistent with the “laws” of physics, but an interpretation of the jets at the comet as electrical discharges would severly violate those “laws” and massively contradict measurements.
            The question has been about the resolution of one those obvious severe violations of the “laws” of nature.
            More precisely about the violation of charge conservation:
            https://en.wikipedia.org/wiki/Charge_conservation

          • Sovereign Slave says:

            Uh huh. And how many experiments have been done IN SPACE to determine exactly how electricity operates in that arena? You say it violates laws, but the same thing could no doubt have been said of sprites and other electric phenomenon until they were better understood, or their existence became irrefutable. Even in the video I linked, they discovered something new, that lightening has a strong x-ray signature…hmm, something you find pretty abundantly in the cosmos as well, huh? I wonder if there could be a connection?

          • THOMAS says:

            @ Sovereign Slave

            “To Harvey, Gerald and company, not to speak for Thomas, but I think it’s obvious that he’s making the point that the phenomena of electricity, especially as it exists in nature, is really not well understood at all, can be very hard to make sense of, is difficult to measure, model, math, and define in all its manifestations, and is only known to exist in some instances based on observation alone, such as sprites, though there are no real explanations behind that knowledge. Etc.”

            Thanks for putting my position into a nutshell, Sovereign Slave. It amounts to saying that it is rather unfair to ask others to run when you yourself have barely learnt to walk (cf. Harvey’s “baby steps for idiots”…)

            BTW, my thanks do not signify that I’m trying to enlist you to any sort of EU cause, since I’ve understood that your training and work in the humanities have well equipped you to distance yourself from any too partisan approach and thereby to adopt a sufficiently objective viewpoint to be able to detect the underlying, unconscious patterns of conformity.

            For my part, I’d like to take this opportunity of recording that my contributions are motivated essentially by my total rejection of mainstream Big-Bang, gravity-only cosmology (going back around 15 years), after being a standard, unquestioning conformist for several decades. (It was Halton Arp’s conclusive, empirical demonstration of the intrinsic nature of redshift which acted as the real eye-opener).

            The EU model I eventually turned to as being the most interesting alternative model in terms of its successfully explicative and predictive power still obviously needs to be filled out, given that there has been zero public funding for research in the field of plasma cosmology over the last century, compared with the billions of dollars poured into attempting to confirm the standard theory during the same period, with diminishing success. I believe that Comet 67P will be an important milestone in operating the long-overdue paradigm-shift, if all the acquired images and data are finally released and we are thus at last able to construct a cosmological model based on observation and evidence rather than on prior belief.

          • Gerald says:

            Sovereign Slave, there is a HUGE difference between explorational discoveries and violations of best-tested laws of nature, in the case of charge conservation up to more than 20 digits accuracy.
            Those “laws” hold in any ever tested or observed environment anywhere in the laboratory, and anywhere in the observed universe from high vaccuum, near absolute zero as well as for stars, highest-energy cosmic rays or LHC experiments. Our modern technology would fail miserably from the very beginning, long before you could even think of plasma experiments or space exploration.
            Sprites are very well within the constraints of these laws of nature, they just haven’t been known before their discovery, like the southern woolly lemur hasn’t been known before its discovery.
            You need A L O T more to only remotely scratch at the validity of these laws than armwaving and obvious mis-interpretations of images.

          • Kamal Lodaya says:

            Thomas: I believe you are right about the importance of 67p, but not in the direction you hoped for. 67p has destroyed the “electric discharge machining” model of formation of dust jets. The cliffs of Hathor seem to be ideal “rock-like” formations where we would expect to see this process taking place. But we do not find any dust jets from Hathor. We find the jets instead from almost every area of 67p which has a dust cover. Supporters of the electric theory have often said on this blog that no sublimation is being seen. But as Harvey says the indirect evidence for sublimation is quite strong so one cannot discard sublimation. With no indirect evidence to support it I think EDM is a goner.

          • Sovereign Slave says:

            @Gerald
            Well, I was wondering when someone would finally pull out the big guns and introduce the southern woolly lemur to prove their case, so touche. And in the same post, you’ve perfectly captured I think much of the nature of the ongoing debates (A L O T of intellectual hand waving indeed). But sure, there are obviously well established natural laws, but even these require accurate interpretation and application in new environments, can be acted upon in unexpected ways by other laws and unknown or multiple phenomenon, be misinterpreted, etc etc, so as much as I’d like to just take your word for it (even though you almost had me at lemur), I’ll continue to reserve judgment on all things related to P67.

          • THOMAS says:

            @ Kamal Lodaya

            “67p has destroyed the “electric discharge machining” model of formation of dust jets. The cliffs of Hathor seem to be ideal “rock-like” formations where we would expect to see this process taking place. But we do not find any dust jets from Hathor. We find the jets instead from almost every area of 67p which has a dust cover.”

            We obviously haven’t been looking at the same pictures over the last few months…

            The vast majority have shown jets from the neck region and/or from Hathor or the opposite cliff-face, the most emblematic of the latter being the famous “plumber’s pipes” image:
            http://blogs.esa.int/rosetta/2015/03/20/cometwatch-14-march-6-hours-later/
            but also: http://blogs.esa.int/rosetta/2015/03/06/cometwatch-28-february/
            and:http://blogs.esa.int/rosetta/2015/02/13/last-stop-before-close-flyby-cometwatch-9-february/

            In fact, until the last month or so, when jets have been increasingly observed emanating from the rocky regions at each ends of the longitudinal axis, virtually no jets have been observed from “almost every area of 67p which has a dust cover” (unless you can refer to the images concerned…).

            As I have commented before, Kamal, your constant vague, hand-waving, statements backed up by absolutely no references, hardly serve your cause.

            In the meantime, the multitude of precious OSIRIS images which must clearly show the precise point of emission of the “jets” are still strangely being kept carefully under wraps. One increasingly wonders why…

          • THOMAS says:

            @ Kamal Lodaya

            Sorry, I forgot the recent OSIRIS image of “sunset” jets which are also clearly emanating from rock rather than from a “dust-covered” region…

            Far from “destroying it, all of these images, on the contrary, totally *support* the EU model.

          • Gerald says:

            Sovereign Slave, you are of course right, that we always need to be careful not to make premature conclusions. That’s why science appears to advance slowly in many cases.
            But try to write a waterproof paper yourself. You’ll see, it will keep you busy for quite a while.

        • Sovereign Slave says:

          Well said, Gerald, and agreed. And I am well aware that me making comments on the Rosetta science is somewhat like a cro magnon critiquing the workings of a gentleman’s watch, but missions of discovery like this are incredibly exciting, and it’s hard not to pipe in. But I do presume some latitude in believing contending/questioning viewpoints make for better considerations. As John Wooden said, “When everyone is thinking the same, no one is thinking.”

      • Sovereign Slave says:

        Well, I guess if consensus cosmology can invent things like black holes that violate very well known,very well established physical laws in order to explain things, not sure how you can criticize others by accusing them of the same thing. Regardless, please explain how this new finding (and isn’t it an electrical phenomenon?) supports sublimation theory or models. Also, if comets are so well known and understood, and their models at least remotely accurate, why have they been completely, absolutely useless in predicting much of anything about this comet?

        • Harvey says:

          Black holes of course are irrelevant red herrings, and yet again it supports water vapour (not that it needs it) which has no other source.
          Semantic arguments are generally rather pointless, but no, unless you are going to start calling everything involving an electron ‘electrical’ it’s not ‘electrical’ in the normal usage of the word. It’s an addition to the zoo of such process that go into the the known-for-decades plasma which surrounds the comet.

          ‘Failure’ – well sure, you can call it that if you want – though in fact a good few aspects, specially the plasma data we’ve seen so far, are pretty much as expected. That’s what science does; it builds models *consistent with known physics and data* then it checks them – we build Rosetta. And the bits that are wrong we fix – *consistent with known physics and the new data*; that’s how science works.

          In contrast, despite excellent data on the density, it’s just denied; must be wrong, because the EU knows it’s rock.
          Despite the fact that there is absolutely NO mechanism by which the water can come from the solar wind, it must do, because the EU knows it does.
          Despite the fact there is absolutely NO credible mechanism to run these discharges in terms of the current source, charged comet etc, they *are* discharges, because the EU knows they are.
          Ditto, the fact that we don’t see the spectroscopic signature or the magnetic field they imply.
          Then of course discharges are very poor at transporting neutral gas, let alone dust, but that’s not an issue, the EU just know it does.
          The only ‘evidence’ at all is the frequent assertion that they are obviously discharges based on visual appearance – when actually that resemblance is extremely superficial, and largely asserted by people who don’t actually seem to have seen many discharges or know much about them.

          The bizarre thing about this so called EU theory is that it doesn’t actually exist! There are no real predictions even qualitatively, let alone quantitatively. No numbers, no formulae, just nothing at all; it’s just an assertion backed up by nothing. A line from Macbeth comes to mind.
          So eventually 67P and a dead Rosetta will sail away, and science will be left with much improved models, which will still be incomplete and maybe wrong in some areas. But they will fit the data and the physics, aside from (generally very rare) actual mistakes.
          I guarantee however the EU, or much of it, will still be yelling ‘it’s all discharges, you didn’t make the right measurements, the data that proves us right is being hidden’ etc etc.
          The interesting thing about it is probably the sociology/psychology of such a phenomenon.

          • ianw16 says:

            @Harvey

            “The bizarre thing about this so called EU theory is that it doesn’t actually exist! ”

            Quite so. And where they do bother to put things down in writing, it is easily shown to be wrong. Take any of their proposed electric sun models, for instance.
            Even their explanation of why comets exist, for instance:
            From http://www.holoscience.com/wp/comet-…ink-confirmed/
            “‘In addition to removing dust, the gargantuan electric forces of an interplanetary thunderbolt are able to loft entire mountains into space from the surface of a planet. Comets and asteroids can be formed this way.”

            And would also be vapourised in this way, but hey ho.

            And, from the same page:
            “The Electric Universe proposes that their origin is identical (*that is, comets and asteroids*) and that a cometary display is due entirely to highly eccentric motion of a charged body in the radial electric field of the Sun.”

            Thereby totally ignoring the fact that there are many asteroids with highly eccentric motions that have been observed.

            67P/C-G: (comet):
            aphelion 5.68 AU, perihelion 1.24 AU, eccentricity 0.64, period 6.44 yr, volume 21.4 km^3, mass 1.0 x 10^13 kg, density 0.47 g cm^-3.

            4179 Toutatis (S-type stony (silicate rock) asteroid):
            aphelion 4.12 AU, perihelion 0.94 AU, eccentricity 0.63, period 4.02 yr, volume 23.8 km^3, mass 5 x 10^13 kg, density 2.1 g cm^-3.

            Strange.

          • Sovereign Slave says:

            @Harvey
            LOL. Yes, I completely agree, “black holes of course ARE irrelevant red herrings.” That’s why I used it as an example. Although, while black holes are extremely suspect scientifically, there’s no arguing that monetarily they’re one of the biggest cash cows in history. I’d be willing to bet that no other single IDEA has ever generated more money, besides the Big Bang IDEA that is. And I definitely agree with your last sentence, the sociology/psychology of thought systems is very interesting, is what much of my background is in, and as I’ve stated before here, is what I find fascinating about many of the posts. And it’s equally fascinating to me that even as you see and point out the phenomenon in others, you seem completely blind to the fact that you’re fully exhibiting and practicing it yourself. As you’ve stated, the ice HAS to be there, there are no other explanations. So that belief fuels all your arguments, and it fully captures you and locks you in, which is the nature of beliefs, and all those that don’t hold to that belief are obviously cracked in your mind. Suspending one’s beliefs is incredibly difficult, especially when there are so many social/psychological things supporting them, but it’s a great exercise and can help avoid becoming too dogmatic.

          • THOMAS says:

            “The bizarre thing about this so called EU theory is that it doesn’t actually exist! There are no real predictions even qualitatively, let alone quantitatively. No numbers, no formulae, just nothing at all; it’s just an assertion backed up by nothing. A line from Macbeth comes to mind.”

            Harvey, you seem to have conveniently forgotten the explicit predictions made by Wal Thornhil concerning the Deep Impact encounter with comet Tempel 1, which were posted on the Thunderbolts website on July 4, 2005, which was the day immediately before impact….

            Several of his predictions, which were totally incomprehensible to standard theory proponents, turned out to be absolutely correct, most famously and spectacularly, of course, his prediction of an initial, pre-impact flash which was indeed observed, to the utter amazement and confusion of the Deep Impact mission scientists. What Thornhill wrote was:
            “Electrical interactions with Deep Impact may be slight, but they should be measurable if NASA will look for them. They would likely be similar to those of Comet Shoemaker-Levy 9 prior to striking Jupiter’s atmosphere: The most obvious would be a flash (lightning-like discharge) shortly before impact.”
            That is EXACTLY what happened.

            The full post can be found here: http://www.thunderbolts.info/tpod/2005/arch05/050704predictions.htm

            Many of his other predictions were also completely accurate. Now that is the sign of a successful model. (Thornhill also quite simply had the guts to put his reputation on the line…) It’s a very far cry from the mere “expectations” of the standard ‘dirty snowball’ model concerning 67P, which have all been utterly disappointed by the reality of the images and the data acquired by Rosetta.

            BTW, which line from Macbeth were you thinking of?

            In return, I offer the famous lines from Hamlet which, although written over 400 years ago, remarkably sum up the limitations of the modern-day standard theory conceptual tool-box:
            There are more things in heaven and earth, Horatio,
            Than are dreamt of in your philosophy. (Act I, scene 5)

          • THOMAS says:

            “BTW, which line from Macbeth were you thinking of?”

            Don’t bother, the line from Macbeth just came back to me (strange how the brain/memory works, isn’t it: it’s all down to electricity powering the neuronal circuits in ways we will never fully understand…).

            Thanks for the “idiot”, if it’s meant for people like me.

            I’ve stated before that the people on your side of the argument would do better to refrain from gratuitous insults and abuse (however well disguised) in lieu of actual scientific argument.

            You will not be surprised to learn that personally, I believe that the “tale […] full of sound and fury,
            Signifying nothing” perfectly describes mainstream cosmic theory, with all its elusive “dark/black” stuff and its other impossible physical entities and phenomena. Hamlet’s words to Horatio (see above) are also for the mainstreamers.

          • Gerald says:

            THOMAS, obviously you didn’t understand, what “baby steps for an idiot” means.
            Since centuries, and particularly detailed near the year 1900, it became clear, that any reasoning must be able to be broken down to a handful of strict logical rules to be conclusive. The probably most famous atomic step of logical reasoning is the modus ponens:
            https://en.wikipedia.org/wiki/Modus_ponens
            So, if you try to convince scientifically educated people from a fringe idea, you need to break down this idea to seamless steps of reasoning to fill the gap between commonly accepted assumptions (“knowledge”) and your idea, such that these individual steps don’t leave space for ambiguous interpretations.

            In the case of suggested high electric discharge activities at 67P, there is a huge gap e.g. between the well-tested conservation of electric charge and the suggestion of a strongly discharging comet.
            This gap/contradiction is evident for scientifically educated people.
            Hence your idea to be considered as meaningful, it needs to be counterchecked against well-tested laws of nature. This check is refused by electric universe people, and it appears to be impossible to be filled in by scientifically educated people.
            There is in contrast abundant evidence for the jets to consist mainly of dust, which scatters sunlight, and gas from sublimated ices or clathrates.
            So you shouldn’t be surprised, that the electric discharge interpretation of the jets of 67P is called “nonsense” by scientifically educated people.

            The – from your point of view – idiots, since they don’t understand your ideas, need help from your superior mind. The appreciated help would be logical baby-steps, e.g. starting with an explanation of the electric circuitry allowing for huge amounts of charge presumed to be discharged.

        • Kamal Lodaya says:

          Sovereign slave: We had plenty of science before we went to the Moon, but we still learned many things by sending spacecraft there. No one accused the scientists then of being “completely, absolutely useless” because many things were found which were unanticipated.

          As I wrote in an earlier post, comets have two kinds of tails: dust tails and ion tails. There are different models for how these tails are supposed to form. Dust tails were explained by a sublimation model. It was said that ion tails were due to the solar wind. The question is, which particles in the solar wind and how do they do it? (For example, Alfvén proposed a possible mechanism in one of his papers.) That is the question addressed here.

          As a proponent of the electric theory, you are only interested in what this paper means for electric theory, or otherwise what it means for the downfall of sublimation. But the comet is not interested in proving or disproving our theories, it just does what it does and leaves us the task of figuring out what it does.

          • Sovereign Slave says:

            Hi Kamal,
            You could of course be quite right, there may indeed be (and no doubt are) a combination of factors contributing to the tails and other phenomena going on with P67. The ones being bantied about are Marco’s/A.Cooper’s stretch theory, EU, and sublimation. Stretch theory is great because I think it’s added a lot to the discussion, and has caused others to consider their own positions more than they normally would, and who knows, it may wind up being the best overall model.

            But as to your first comment, my statement doesn’t at all refer to the scientists, but to the sublimation model which has pretty much been useless in explaining or predicting findings and cometary behavior. Obviously there is a ton of things to still learn about comets, which is the reason for the mission, but very few if any of the findings to date directly support the sublimation model, and many seem to outright contradict it. That would be fine if the sublimation model was one of several that were being honestly considered by open minds, but that’s not generally been the case. The attitude and ongoing presentation in articles and comments has been that sublimation is THE model, it’s right, and we just need to figure out how the sublimation is working, and all other considerations are either non events, or just plain crazy talk. As I’ve said in other posts, once someone is locked into their beliefs, objectivity and truly rational consideration goes out the window. But as you say so well, “the comet is not interested in proving or disproving our theories, it just does what it does and leaves us the task of figuring out what it does.” Why therefore should anything it does be surprising? The only reason anyone should be surprised is if one is too locked into their beliefs about what comets are and how they behave.

        • originalJohn says:

          You have been told the answers to your questions many times Harvey. Why keep repeating them. You have to realise also that the actual values you ask for are unknown and the ESA scientists have the pioneering opportunity of measuring them in a natural situation.

          But, for one more time, what is proposed by the electric comet hypothesis is this. The nucleus is a charged body moving in the electric field of the heliosphere. It is negatively charged having spent the slow moving part of its orbit in a region of the solar system with greater negative charge, beyond the orbit of Jupiter. As it returns to the other focus of its elliptical orbit, the Sun, it accelerates and moves through the solar electric field into increasingly positively charged regions. A potential gradient is therefore established between the nucleus and its surroundings causing a discharge from the negatively charged surface of the nucleus to the more positively charged virtual anode region of the heliosphere encountered. And because it is in motion along the potential gradient of the heliosphere it is always encountering a new more positive potential. It will continue to discharge provided it retains a more negative potential than its surroundings.
          This process is unique to comets because of the extreme elliptical shape of their orbits. The planets and the asteroids also follow elliptical paths but their orbits tend towards circular so in general they do not discharge visibly as their motion is in a region of the heliosphere of approximately uniform potential for an extremely long period of time and they achieve the local potential themselves. Therefore no potential gradient and no discharge. Some of the more elliptically orbiting asteroids have been observed discharging and some have been reclassified as comets.

          I repeat we do not as yet know the discharge current of 67P or any of its electrical properties. But knowing as we do that the glow discharge will manifest itself in a plasma at very much less than 1 amp and a potential difference of a few hundred volts we can surmise that those are the order of figures that will eventually be measured for 67P. If the current density of the discharge increases significantly near perihelion, which is one possibility, we may see a switch, almost literally, to the much more intense arc mode discharge, with a current of tens or hundreds of amps. A potential barrier must be overcome to achieve this jump, maybe 1000 volts but once the arc is established the voltage drops by a factor of 10 to much less than the glow voltage.

          These Harvey are the sort of figures we will be looking for.

          Finally, it is possible that in the approximately circular path of the perihelion phase with a constant potential/time relationship that the discharge will reduce considerably or stop. For that period the nucleus would have little or no charge difference from the immediate solar environment. If there is insufficient time available for this the discharge will continue. In any event as the nucleus begins the return leg of its journey it will once again be moving through the solar field to regions of continuously new potential, this time more negative, and it will either restart or continue to discharge. There are a range of possibilities.
          Eventually, if it survives, it slows down in the strongly negative outer range of its orbit and the discharge stops as it achieves the potential of that region. Then once more around the Sun.

          There you go Harvey a broad, rough description with order of magnitude numbers as demanded. No distraction. Exactly to the point. Perhaps you could in a similar way post your hypothesis for criticism. I demand it.

          The electrons, by the way, that constitute the virtual cathode at the edge of the solar electric field, stream, with well documented intensity, from the interstellar medium.

          • Gerald says:

            Originaljohn, first, thanks for the comprehensive overview.

            To be able to do any quantitative considerations, is the electric comet hypothesis assuming “mainstream” electromagnetism (Maxwell) -including predicative logic, algebra, calculus, or does it assume a different physics?
            In the latter case, which rules of physics and reasoning are considered valid?

          • Gerald says:

            Originaljohn, this electric comet model has the obvious difficulty to explain the origin of the positive charging of the anode region in the inner solar system as well as the origin of negative charging of the cathode region in the outer solar system.
            You need some inaccessible (in hyperspace?) engine to separate charges and to transport them to the two electric poles via invisible wires through some hyperspace.

            This gap can be closed by moving both electrical poles, anode and cathode, to the Sun. The Sun, like a battery or an electric generater itself is electrically close to neutral. But it seperates electrical charges, e.g. in its interior, and provides both, positively and negatively charged regions.
            Electrical currents, e.g. in the solar corona, close the electric circuit.
            That way you get both, electric and magnetic fields, as observed, and you get them on a reasonable order of magnitude.
            No violation of Coulomb’s law, and no violation of the conservation of charge.

            Your playground now is the solar dynamo:
            http://www.cora.nwra.com/~werne/eos/text/dynamo.html

            The electric comet hypothesis is revealed as unbased.

      • originalJohn says:

        Why do you use the word invent Gerald. A hypothesis is a suggestion of what might reasonably be happening. Z pinch is a perfectly reasonable phenomenon to invoke as it is a well established behavioural characteristic of plasma electric currents.
        There are no abundant contradicting measurements that I am aware of, such as ion densities at different points within the coma, including close to the nucleus surface. If you are aware of these please share.

        “repulsive Coulomb forces” Are you suggesting that electrostatic repulsion forces between for example protons could nullify the increase in current density promoted by the Lorentz force induced pinch effect. The vast experience of the fusion researchers would deny that. They routinely achieve 20 orders of magnitude increase in ion density in plasmas.

        As far as the combustion reaction is concerned Gerald it is a standard chemical reaction, widely understood. “they” did not invent it in the comet context. It was proposed as a hypothesis by me, as you know, because the reactants are there at the nucleus surface and the reaction products have been identified in the coma, and the solar protons are there as a continuous flux ( “continuum” ?) to supply the energy to release the oxygen and initiate the reaction. One solar proton can dissociate hundreds of Si-O bonds. This hypothesis cannot be dismissed by presumptive calculations or dogma. It could be confirmed or refuted by measurement of what is happening at the nucleus surface, as also could the ice sublimation hypothesis.

        Nobody as far as I am aware has suggested or implied any conspiracy. The defenders of the “establishment” like yourself are the only ones who refer to that. What you are defending however is a consensus, an explanation upheld by the majority by agreement. This is not a conspiracy. My contention is that the explanation is not supported by fact. Therefore good to look for other explanations.

        So let us see the electrical, plasma and temperature data that could easily confirm or contradict the combustion/ plasma discharge hypothesis or the ice sublimation hypothesis. That is what Rosetta is there for isn’t it. To find out how comets work.

        • Gerald says:

          Originaljohn, a lot could be said. in this post I pick out just one of many issues: Assumed, the non-existent strong local currents and z-pinches would exist near the comet, how would the magnetic fields of the z-pinches and currents be shielded?

          https://en.wikipedia.org/wiki/Pinch_(plasma_physics)
          “A pinch is the compression of an electrically conducting filament by magnetic forces.”

          http://rosetta.jpl.nasa.gov/news/rosetta-and-philae-find-comet-not-magnetised-0
          “‘During Philae’s landing, Rosetta was about 17 km above the surface, and we could provide complementary magnetic field readings that rule out any local magnetic anomalies in the comet’s surface materials,’ says Karl-Heinz Glassmeier, principal investigator of RPC-MAG on board the orbiter and a co-author of the Science paper.”

          • originalJohn says:

            The magnetic field which establishes the Lorentz pinch force Gerald is local to a particular plasma current filament. It is distinct from the magnetic field of the nucleus. It is not necessary to detect it to know its presence. If there is a current flowing in a conductor the corresponding magnetic field is there. The greater the current the stronger the field and the greater the force. Such local fields in plasma are capable of radially compressing plasma filaments to produce increases in current density of many orders of magnitude. That degree of force can arise for example as ions are accelerated within double layers by the extreme potential gradients that can exist there. The general velocity of solar current ions is hundreds of kilometres a second. In double layers they can be accelerated to relativistic levels. The regions that need to be examined for the presence of these currents are the boundary between the coma and the heliosphere and the boundary between the coma and the nucleus. Other plasma boundaries are however also likely within the coma.

        • Gerald says:

          Repulsive Coulomb forces would disrupt any strongly charged fluffy dust grain. The comet therefore cannot be strongly charged.
          Strong surface charging would (after partial charge exchange) also immediately eject any loose surface material.

          https://en.wikipedia.org/wiki/Coulomb's_law

          http://blogs.esa.int/rosetta/2015/04/09/giada-investigates-comets-fluffy-dust-grains/
          “…the fluffy aggregates are slowed down and disrupted creating the showers and sub-showers seen by GIADA.”

        • Gerald says:

          Combustion doesn’t work.
          Even with 1000 freed oxygen atoms by one proton you would still be a factor 10,000 below the needed amount of oxygen to explain the measured CO2 and H2O.
          But actually you get just about 0.01 oxygen atoms per proton. Other protons are simply absorbed, without sputtering oxygen. The oxygen is happy with the silicon. Oxygen and silicon radicals just form the silicate again.

          So you are nine orders of magnitude off.

          Assuming your suggested mechansim would work by some unknown magic, you would get excess silicon, which would also be sputtered, but it’s remarkably absent.
          Hence your hypothesis is refuted by measurements. Where is the clear silicon signature either in spectral data or in ion measurements?

          Of course calculations and logic are your enemies, since they easily dismiss your hypotheses.

          • originalJohn says:

            You don’t know the proton current density at the nucleus surface Gerald. You are assuming it. And what you are talking about is point measurements of CO2 and H2O extrapolated according to a hypothetical model. The coma is estimated to be 100,000 km in diameter. You have no idea what the actual levels are. Atomic oxygen is another point measurement and of free oxygen. It does not include reacted oxygen.
            Oxygen has no emotion Gerald but if it did it would be as happy with hydrogen and carbon. Neither do you know how much oxygen would be released by 10 keV protons sputtering rock under comet conditions. You are guessing based on irrelevant lab bench technology.
            As far as the silicon signature is concerned, publish the spectral data and the ion measurements and publish the analysis of the dust, and publish your interpretation.

            There is nothing in published measurements to refute the combustion hypothesis. The measurement that could easily refute it and support the ice sublimation hypothesis would be temperature measurement of the jets. So do it and publish it. Then we can speak again.

            My enemy by the way is baseless assumptions presented as facts. Calculations and logic are of course fine.

        • Gerald says:

          .”That is what Rosetta is there for isn’t it. To find out how comets work.”
          I agree with these two last of your above sentences.

        • Gerald says:

          Regarding evidence for ices: You may like to read e.g. these two papers about the detection of volatile species:
          http://www.hou.usra.edu/meetings/lpsc2015/pdf/2716.pdf
          http://www.hou.usra.edu/meetings/lpsc2015/pdf/2947.pdf
          The straightforward, and the only known reasonable causes for the presence of these volatiles are the presence of ices and/or clathrates.

    • originalJohn says:

      You are talking about the background proton density again w16. Actual proton density at the nucleus surface unknown. Actual boundary factors likely to affect it unacknowledged.

  • originalJohn says:

    Very interesting results from P. Feldman et al ; the unexpected identification of atomic hydrogen, oxygen and carbon in the spectra of the comet coma with separation between the light reflected from the nucleus and what is described as the comet light or the intrinsic radiation from the near nucleus coma.
    The interpretation is however dubious. A mechanism is hypothesised without considering any other possible explanation for the presence of these atoms. The proposed mechanism is a two step one of ionisation of water or carbon dioxide molecules by solar ultra violet photons with sufficient energy, ( ie those towards the shortest ultra violet wavelengths. The ionisation energy of water is typically 12.6 eV , greater than that of the Lyman alpha photons) and subsequent dissociation of other water and CO2 molecules by energetic freed electrons. The two stage hypothesis presumably selected to support the likely electron dissociative excitation of H2O suggested by the non variable relative intensities over time of atomic hydrogen and oxygen. Atomic carbon emission is however also attributed to electron dissociative excitation of CO2 even though its relative intensity does vary with respect to atomic hydrogen and oxygen. This two stage mechanism also is proposed despite the fact that the the ionised electrons could have no greater energy than the extreme ultraviolet photons that released them and which themselves would be capable of dissociating the H2O and CO2 molecules without the the contribution of the electrons. No mention either of the proportion of neutral molecules ionised. In the past ESA have suggested that a proportion of 1ppm of neutral material ionised would be consistent with photoionisation ie a weak effect that reflects the proportion of ultraviolet photons with sufficient energy in the solar radiation flux. Is this sufficient, according to their mechanism, to account for the intensities observed or their estimated electron density of a few hundred per cm cubed and with measured peak energies in the range 25-50 eV, well into the extreme ultraviolet range and therefore likely to be capable of much less than 1ppm ionisation of neutrals, simply through being even less abundant.
    They may be right in their interpretation but there is no evidence that they are and there are reasons why they might not be. There are other sources of atomic hydrogen and carbon (without dissociation) and one is incomplete combustion of hydrocarbons. CO is also an incomplete combustion product. Under other conditions surplus oxygen could be a combustion product in molecular form. It absorbs ultraviolet radiation and has a low dissociation energy of 1.5 eV. What oxygen level is there in the coma and is it dissociating. And water and CO2 are standard products of either incomplete or surplus oxygen combustion.
    In addition the energy of solar protons, typically in the range 1 – 10 keV, as either an ionisining or a dissociating medium is not considered. Neither is a potential source of electrons in the discharge current from the nucleus. High electron densities in the hundreds per cm cubed have previously been measured by ESA in the coma. Is such a density accounted for by ionisation of neutral molecules by the minute proportion of solar photons with energies greater than 10 eV.
    The interpretation by Feldman et al is a presumption for which there is no conclusive evidence, therefore no more than an interesting hypothesis. Fine if we are clear about that.

    • ianw16 says:

      @originaljohn
      “In addition the energy of solar protons, typically in the range 1 – 10 keV, as either an ionisining or a dissociating medium is not considered. ”

      Which part of “there aren’t enough protons in the solar wind to account for the obderved water production” didn’t you understand?

      • originalJohn says:

        Ah 16 you know the typical solar wind proton density near the surface of the comet nucleus. Perhaps you would be good enough to share the figure with us and your source.

        • ianw16 says:

          This has been explained numerous times. The density has been measured on a regular basis at 1AU, and at other distances by other spacecraft. At 1 AU it is around 7-10 per cm^3. This diminishes with distance via the inverse square law. 1/r^2.
          At roughly 3 AU where the first measurements of water were made (roughly 1 litre per second) it would therefore be ~1 proton cm^3. There are ~ 3.3 x 10^25 molecules of H2O in a litre of water. The maths has been done here before to show that at that density there is a deficit of, generously, ~ 10^7 protons cm^3 to explain the water production as seen then. I suspect it would be closer to 10^8 or more by now, not to mention at other comets where water has been identified.
          Now you have two options here: increase the current proton density by the aforementioned factors, or keep it as it is, but increase the velocity by those factors.
          Having done that, I suggest you email the mission designers and ask them what those ion fluxes would mean for poor little Rosetta.
          So I reiterate, this is a non-mechanism.

          • ianw16 says:

            @Originaljohn,
            Sorry, you asked for souces. There are many, relating to various comets, but for this comet there was the paper that was released as part of the Science magazine special edition, of 23 Jan 2015, at: http://www.sciencemag.org/content/347/6220/aaa0571.short
            If you haven’t already got it, then it is still free, but you may need to register to access the full article.
            Interestingly, they had an increase in the solar wind flux of a whole order of magnitude on one of their observation days. However, this is nothing to get too excited about, as it is still at least 6 orders of magnitude to small to account for what the EU ideas call for. The authors don’t state the reason for this increased flux, but a bit of digging around shows that it is most likely due to this: http://spaceweather.com/archive.php?view=1&day=13&month=09&year=2014

          • originalJohn says:

            The repeated explanation ian is misguided and presumptive. You refer to proton densities at 1 AU ie in the vicinity of the Earth. As you know such measurements are made to monitor the impact of space weather on the planet and its orbiting hardware. There is no validation for extrapolating the 1 AU figure to every point in the heliosphere. This ignores the real possibility of extreme increases in ion density that can occur in plasma and which are very likely to be occurring in the vicinity of this and other comet nuclei, judging by their behaviour. Not necessarily however likely in the immediate vicinity of the orbiter. The charge state of the nucleus and the coma enveloping it are likely to be different from that of the orbiter. Neither is there any reason why the behaviour of the plasma surrounding the two should be similar. If the orbiter gets close to the nucleus that is a different story and it is very likely it would be adversely affected then. Local effects are therefore significant. Largely unmeasured local effects.

            Even though it is possible for the proton density to be increased by Lorentz forces by many orders of magnitude, as a natural self induced effect in the solar wind plasma, to provide sufficient protons in a proton/ oxygen reaction at the nucleus surface and to account for the measured water in the coma, this reaction is not necessary.
            There is another potential source of water which is the reaction of oxygen from the rock with hydrocarbons which coat the nucleus surface. This would be energised by the naturally densified solar proton flux. No measurements have yet been published to show that this cannot be happening. Data from analysis of the composition of the coma does however confirm the presence of multiple atoms and molecules that could be the products of this reaction (reactions).
            Measurement of proton (or electron) density at one point ( or even one radius) in the coma is meaningless since large scale variations in plasma ion density can occur over comparatively short distances ( a few Debye lengths). A map of proton ( and other ion densities in the coma) is required.
            If the mission designers have not taken into account the possibility of very large local increases in solar wind ion density ( and/or velocity) then they may well be surprised. They would however have no data relating to this. They would have to recognise it as a possibility, from their knowledge of the natural behaviour of plasmas.

            So alternative mechanisms to the ice sublimation model still stand, awaiting contradictory data or measurements of any sort relating to them. The ice sublimation model also awaits such data.

  • THOMAS says:

    The surprise expressed by the scientists mirrors the now-famous “expect the unexpected” advice from Holger Sierks many months back. May I point out that the notions of “surprise” and “the unexpected” only make sense with respect to standard theory EXPECTATIONS based on mere ASSUMPTIONS which have constantly and invariably been respectively disappointed and disproved ever since 67P’s arrival at the comet.

    I think this discovery should be set in its wider context. This detection of huge quantities of hydrogen and oxygen atoms/ions in the immediate vicinity of the comet surface is just the last (but perhaps now the biggest) in the long list of other total and utter surprises which should now be recalled before they simply become taken for granted and conveniently dismissed as somehow being irrelevant:

    -the improbable irregular, roughly hourglass shape of the nucleus
    -the rocky, rugged, chaotic, appearance of the terrain featuring identically Earth-like features such as sheer cliffs, canyons, chasms, pits, outcrops, boulders of all shapes and sizes strewn or piled up everywhere but mainly at the foot of cliffs and, the real killer, unmistakable stratification everywhere, at every scale
    -the large, roughly circular (but often hexagonal) “depressions” which would still be blandly described as “impact craters” (as they presumably still are on other comet nuclei we have imaged from a distance), if we had not managed to get close enough to them to falsify the “impact crater” theory
    -the extraordinarily low albedo of the nucleus, making 67P one of the darkest objects in the Solar system, giving it a “burnt-to-a-cinder” appearance, associated with multiple complex carbon compounds
    -the hardness of the surface which initially prevented Philae from getting a grip on it and then caused it to bounce so high as to almost attain escape velocity, never to be seen again, even fleetingly
    -the total failure to detect water ice (or any other ice) anywhere on the surface, even in the most minute quantities
    -the average surface temperature which, on Rosetta’s arrival at the comet, was a whopping 30°K higher than the standard model had predicted (I repeat: 30°K, not 0,3°K or 3°K but 30°K)
    -the paradoxical location of the highest temperatures (the highest by far), recorded all along the bottom of the Hapi Valley neck region, despite this being precisely the region of the comet which receives the least input from solar energy since it is shaded from the sun by the towering cliffs on either side
    -the extremely localized nature of the “jets” which, until very recently, were concentrated almost exclusively in the neck region but which now seem to be shifting their preference to axial locations at the top and bottom of the head and body lobes (see the latest cometwatch 21 May post: http://blogs.esa.int/rosetta/2015/06/03/cometwatch-21-may/)
    -the often-observed curving of the jets immediately after their point of origin which thus cannot be attributed to rotational forces
    -the considerable diameter of many jets at their base, totally inconsistent with the “nozzle” mechanism required by standard theory to explain the observed speed (700m/s) and collimation of the jets
    -the increasing emanation of extremely powerful jets from shaded regions of the nucleus, particularly from the top and bottom of the head and body lobes
    -the intrinsic brightness of such jets, right from their heavily shaded bases

    This list, long though it is, only includes the most obviously anomalous characteristics of 67P as compared with standard theory expectations, such as the average citizen scientist has been able to pick up on, from careful study of the scant images and data which have actually been released over the past ten months.

    Every single one of these “surprises”, on the other hand, is an explicit EXPECTATION of EU theory.

    The vast body of yet undisclosed images (OSIRIS, anyone?) and data will presumable reveal infinitely more “surprises” for the standard theory, each one of them even more “surprising” than the others. Holger Sierks himself warned us to expect as much many months ago and the true revelations are at last starting to leak out…

    • Gerald says:

      Wow, interesting! Combustion and lightnings of -50°C, fully consistent with the expectations of electric universe claims.
      I would have expected something like +500 to +1500°C for combustion and 10,000 to 30,000°C for lightnings, a mere 550 to 1550°C or 10,050 to 30,050 degrees off, depending on the joke of the day, really a very accurate prediction of the electric universe proponents.

      In contrast the “standard theory” has been a little off with the fluffiness estimate of the dust layer, leading locally to a discrepancy of up to 30°C; that’s of course much more than the up to 550 to 30,050°C discrepancy to the electric universe. Unforgivable, terrible error! All physics must immediately be abondaned and replaced by the precise predictions of the perfectly elaborated electric universe theory of everything!

      Dream on, electric universe!

      • THOMAS says:

        @Gerald

        I’ve no idea what you are referring to with your “lightnings” and the temperature values you throw off, with respect to comet 67P. They appear to be classic red herrings.

        The EU model, for its part, predicts localized electrical discharge phenomena of varying degrees of intensity, as a function of (and in order to reduce) the charge difference existing at a given time between the comet nucleus on the one hand and the state of the plasma constituting the solar wind in that part of the solar wind it is traversing on the other. The reason why the whole length of the bottom of the Hapi Valley canyon was shown, several months ago, to be by far the warmest part of the nucleus even though paradoxically it receives by far the least sunlight is that for many months, that is precisely where the vast majority of the discharge activity was focused until quite recently. (Now the main focus seems to be gradually switching to the longitudinal axis. It will be interesting to observe whether the updated VIRTIS temperature maps show an equivalent appearance of extensive hotspots at the top and bottom of the head and body lobes respectively, which would be a further confirmation of the EU model).

        Regarding the alleged, unforeseen “fluffiness” of the dust layer to explain the 30°C discrepancy between standard expectations and on-site observations, allow me to say simply that I find the excuse rather feeble (and, of course, scientifically worthless).

        Your silence on all the other items in my long list of real, evidence-based (rather than mere maths-based…) shocks and surprises for the standard theory is presumably a form of acquiescence. I’m not sure that your over-heavy irony about the accuracy of EU predictions, which you seem to be using in lieu of actual scientific argumentation, will convince many people either. Please note, finally, that I personally always base my comments on the evidence of actual observations and that I never resort to the use of such expressions of mere value-judgments, again in lieu of argumentation, as “horribly ridiculous” or “complete nonsense”. It would greatly enhance the actual scientific value of the debates on this blog if the people on your side of the argument could adopt the same procedure.

        • Harvey says:

          Thomas, the one thing you *never* do is base it on evidence.
          The evidence is a density of 470kg/m^3, but apparently it’s solid rock.
          The evidence is trivial magnetic fields typical of the interplanetary value, so no big discharge currents, no Z pinches.
          The evidence is large amounts of molecular water which certainly cannot come from the solar wind, so there must be a water source.
          And so on.

        • Gerald says:

          THOMAS, I’ve explained and shown in due detail, why your claim of martian dust devils being electric discharges are “horribly ridiculous”, see e.g. here:
          http://blogs.esa.int/rosetta/2015/04/20/osiris-catches-activity-in-the-act/#comment-463406

          “my long list of real, evidence-based (rather than mere maths-based…) shocks and surprises for the standard theory is presumably a form of acquiescence.”
          Which evidence? Without math? and without physics? Do you really call this science?

          Those “shocks” just exist within your imagination. In reality the scientists are highly excited. Obviously you’ve never met a member of the science teams. Where else should your completely wrong assessment come from?

          Temperature of lightnings:
          “The core temperature of the plasma during the return stroke may exceed 50,000 K, causing it to brilliantly radiate with a blue-white color.”
          http://en.wikipedia.org/wiki/Lightning#Properties
          If you disagree with this, what discharges are you talking of? What currents do you suppose? If you presume relevant sputtering or effects more intense than sunlight, you need to go up to these intensities.

          If your ideas are intended to be taken only remotely serious, you need to provide at least order of magnitude numbers. Instead you try to pump up 190K versus 220K, which is well within uncertainties considering temperature estimates on the polar night down to about 30K.

          Your “all the other items” are either completely wrong or don’t prove anything regarding electric hypotheses.
          “Intrinsic brightness” is just one of many of your mis-interpretations.

          Example:
          “average surface temperature which, on Rosetta’s arrival at the comet, was a whopping 30°K higher than the standard model had predicted “: wrong in two ways at least, first the estimate referred to a narrow area in the neck region during maximum solar illumination, not to an average temperature. The effect has later been consistently explained by high fluffiness and self-heating effects.

          “the total failure to detect water ice (or any other ice) anywhere on the surface, even in the most minute quantities”: Irrelevant for the existence of subsurface ice, and additionally wrong, since evidence for surface ice has been detected spectrographically.

          “the large, roughly circular (but often hexagonal) “depressions” which would still be blandly described as “impact craters””: Your error. Not an issue for science.

          … and so on.

          About “red herrings”: That applies essentially to all your items. Why waste endless time discussing them?

        • Gerald says:

          For completeness, some simple answers for what you’re trying people to take for issues:

          “-the extraordinarily low albedo of the nucleus, making 67P one of the darkest objects in the Solar system, giving it a ‘burnt-to-a-cinder’ appearance, associated with multiple complex carbon compounds”:
          plus iron sulfide, most of it originating from cosmic dust from which our solar system formed

          “-the hardness of the surface which initially prevented Philae from getting a grip on it and then caused it to bounce so high as to almost attain escape velocity, never to be seen again, even fleetingly”
          The cold gas thruster and the harpoons didn’t fire. The issue with the cold gas thruster has been known before Philae’s separation from Rosetta. The harpoons probably didn’t fire due to a discrepancy of the electric wiring from the plan, the according software has been developped according to the plan, the glitch is known by now and might be used for another firing attempt. The ice screws allone are just able to stop horizontal motion, insufficient to stop bouncing. A crust on the nucleus has been anticipated at least since the design of the mission in the early 1990’s.

          “-the considerable diameter of many jets at their base, totally inconsistent with the ‘nozzle’ mechanism required by standard theory to explain the observed speed (700m/s) and collimation of the jets”
          Wrong in several ways. You’re confusing gas and dust velocity. Nozzles are neither required for collimated jets nor ruled out by observation. Just nozzles above a diameter of more than about a meter are unlikely during early activity.

          “-the increasing emanation of extremely powerful jets from shaded regions of the nucleus, particularly from the top and bottom of the head and body lobes”
          “Extremely powerful” is a bit of an exaggeration. Due to closer proximity to the Sun deeper subsurface layers are warmed up above sublimation/decompositiom temperature of the respective ices/clathrates. Water ice sublimates significantly above about -70°C, slowly starting at about -130°C. As comparison Mars surface temperature at noon near the equator is usually near 0°C in the summer, can be up to +20°C. Mars has a higher albedo than 67P, hence heated less than 67P by the Sun at the same distance.

          “-the often-observed curving of the jets immediately after their point of origin which thus cannot be attributed to rotational forces”
          Is there any confirmation for this opinion? I assume, with rotational forces you mean Coriolis forces. Even if, so what? Dust grains may move to a differently moving gas jet or get in contact with another location on the concave surface of the comet.

    • Marco says:

      Hi Thomas,

      I don’t agree at all that EU theory has *predicted* anything more than that the surprising findings when we visited other comets are typical of comets in general. eg. Dark, bi-lobed shape “dry” surface, jet properties, lack of impact craters etc. Even the temperature readings from flybys are consistent with the findings on C-P.
      Did it predict anything new that wasn’t already partly a surprise finding in previous missions? I don’t think so.

      As far as the falsifiability of EU goes, the density question surely takes the cake. I still cannot fathom that it is considered a serious scientific hypothesis that C-P and other comets are actually the density of rock. I find it an insult to science, and takes all the credibility about some of the sensible challenges you make to assumptions underlying cometary science. The ability to explain away such glaring faults essentially turns EU into an unfalsifiable assertion. Contact Binary is also close to being unfalsifiable – like a fall back theory as other competing theories are falsified because they are more falsifiable.

      I strongly believe water vapour is being emitted from the nucleus. No other explanation makes sense. That does not mean water ice is necessarily on the surface, subsurface or deep down. I do not think the surface is being “eroded”

    • Kamal Lodaya says:

      Sorry, Thomas, but I don’t see why your long list should be expectations of EU theory. Just your saying so does not make them so.

      For example, “the large, roughly circular (but often hexagonal) depressions”, are you saying that EU theory predicted that we would find them on comets before Rosetta got to 67p? I believe you keep updating your list with things which you think have an electrical explanation and conveniently fail to list observations for which you cannot see an explanation. For example, did EU theory predict that comet nuclei would not be magnetized?

      Even if we ignore these matters of precedence, there is no model today (as apart from statements on blogs) where all these consequences are worked out.

  • THOMAS says:

    So now we are being asked to believe that the water allegedly “spewing” from the surface is immediately dissociated into H and O atoms, before coming together to form water again further out in the coma.

    This was hardly “expected” either, was it?

    It seems rather more logical to believe, on the basis of actual observations corresponding to hard data, that no water has ever “spewed” from 67P (or from any other comet for that matter) and that the observed H and O atoms have a totally different origin. Having read through the A&A article (http://www.aanda.org/articles/aa/pdf/forth/aa25925-15.pdf), I’d like to quote, for example:

    “In Figs. 4 and 5, the brightness of the H I Lyman-β line from two off-nadir sequences is USED AS A SURROGATE for H2O abundance along the line-of-sight” (my capitals for emphasis).

    It’s perhaps a naïve question, but why should “surrogates” still be required to prove “H2O abundance” unless, as many of us suspect, no direct detection of H2O has ever been made by the battery of dedicated ROSETTA instruments since arrival at the comet nearly 10 months ago? Direct observation by Alice apparently only concerned hydrogen and oxygen atoms/ions:

    “From the 10 km orbit in mid-October 2014 Alice observed emissions from atomic H and O above the comet’s limb.”

    The rest is pure (and explicit!) assumption and speculation:

    “ASSUMING the observed H and O emissions are primarily produced by electron impact dissociation of H2O, these far-ultraviolet observations COULD be mapping the spatial distribution of water plumes erupting from the surface of the nucleus.” (Note the telltale “COULD be”…)

    A comparison is then made with “the mapping of H and O emissions from water plumes emanating from Jupiter’s satellite Europa (Roth et al. 2014)”. The problem with this comparison is that the alleged existence of “water plumes” on Europa is again a simple assumption, whereas the ELECTROMAGNETIC nature of the “footprint” connection between Jupiter and Europa has long since been established: see the impeccably peer-reviewed, February 2002 ‘Nature’ article “Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter” at http://www.nature.com/nature/journal/v415/n6875/full/415997a.html. There too, there are the same signs of “surprise”, although the euphemistic downplaying is ever-present: to quote the abstract, “The specific physical mechanisms responsible for generating those emissions ARE NOT WELL UNDERSTOOD” (again, my capitals for emphasis).

    Surprise, surprise!

    In any case, what on earth could even be the possible relevance of a comparison between two distinct phenomena which are explicitly claimed to be driven by utterly different forces (“electron impact dissociation of H2O” in the case of 67P and “electromagnetic” forces leaving their “footprint” in Jupiter’s magnetosphere)? EU proponents would claim, rather more consistently, that BOTH phenomena are due to electromagnetic forces (but without the never-observed water “spewing” from the surface of either Comet 67P or Europa, of course).
    Things seem to be going from bad to worse for the standard theory as 67P approaches perihelion…

    Personally, I can’t wait for the upcoming images, data and disclosures.

    • ianw16 says:

      @Thomas
      “It’s perhaps a naïve question, but why should “surrogates” still be required to prove “H2O abundance” unless, as many of us suspect, *no direct detection of H2O has ever been made by the battery of dedicated ROSETTA instruments since arrival at the comet nearly 10 months ago?* Direct observation by Alice apparently only concerned hydrogen and oxygen atoms/ions:

      Yawn. Have you forgotten the VIRTIS data? Link here: http://www.hou.usra.edu/meetings/lpsc2015/pdf/2494.pdf

      You will notice that H2O was detected from its spectral signature. I think you’ll find that this spectral signature is different from OH, H, or O. So your claim is factually wrong. They detected water, and if you read the paper carefully, you’ll see that those emissions were coming from within 0 – ~500m of the comet surface.
      So for the Alice team to assume that these are products of H2O photon dissociation is quite valid, in my view.
      You may also want to see http://www.nature.com/nature/journal/v324/n6096/abs/324441a0.html
      “Post-perihelion observations of water in comet Halley.”
      Again, spectrally identified. No doubt what they were seeing. Don’t they tell you this stuff over at Thunderbolts?

    • Harvey says:

      So, ‘no water…..’ Complete nonsense.
      The Kuiper telescope directly measured water *molecules * using IR spectroscopy as early as 1986
      http://www.ncbi.nlm.nih.gov/pubmed/17773501
      Using a completely different technique, microwave spectroscopy, MIRO has measured it at 67P.
      No one suggests they ‘come together’; most of the neutral water molecules do not undergo these processes..
      As ever, inconvenient data is just ignored.

    • Gerald says:

      Do electric universe proponents still predict a stop of cometary activity near perihelion due to the orbit being parallel to the (nonexistent) planes of constant electric potential around the Sun?
      Or do they already claim, that they’ve always been predicting high activity near perihelion?

      • originalJohn says:

        Instead of misunderstanding or inventing other peoples predictions Gerald why don’t you make some predictions, quick before it is too late.

        My prediction is that the activity could intensify, decrease or stop altogether for a period depending on the potential difference between the nucleus and its immediate environment. We have no way of knowing which it will be although for example daily measurement of that potential difference might allow the relationship to be extrapolated to perihelion.

        We do know from observation of past orbits of 67P that activity has increased to a maximum weeks after perihelion.

        • Harvey says:

          Now that is a really useful prediction; the activity could ‘intensify, decrease or stop altogether’.
          In other words, no prediction at all.

        • Harvey says:

          ‘Daily measurement of the potential difference’; now that’s an interesting suggestion.
          To do that, implies some basic understanding of the ‘circuit’ involved here, which I’ve been asking for since forever.
          So where exactly should I connect my voltmeter?
          If 67P is rock, as we are told, , it’s insulating, so it’s surface need not be equipotential. That a a bit of a problem. Of course if it’s conducting, I’m not quite sure how CONSERT got a radio signal through it.
          And where to I connect the other lead?
          Presumably in this nice thought experiment maybe I could put an ammeter in series with the discharges, and get an idea of currents and current densities. Just so I can choose the right instrument, what order of magnitude of current might it show? Of course it can’t be very high, or we’d have seen the magnetic field; but if it is not very high, how does it transport so much gas and dust (*neutral*) – when the ions are going towards the comet if it’s negative as is asserted.
          Measuring the ‘potential difference’ is a bit of a can of worms; EU ‘theory’ and number don’t mix very well.

          • originalJohn says:

            Yep it is a prediction Harvey. We have no way of knowing which is more likely so the prediction is that the occurrence will be random to us.. Here is another prediction. No ice in any significant quantity will be found. Positive enough for you.

          • originalJohn says:

            Ah Harvey, do you only know one way of determining voltage, as on a laboratory bench. Might I suggest that another property could be measured, for which instruments in the appropriate locations are available, particularly now, then the voltage could be calculated. Any ideas what could be measured.

            No need for your floating ammeter either Harvey. Measure the electron and positive ion densities and speeds in the coma plasma at any point and you know the current. You have already argued your case using the sole published measurement of such figures to suggest the current might be insufficient for certain reactions.

            And finally Harvey once we are able to confirm the nature of the jet discharge ( those instruments are there again) we can can know with certainty the voltage and current within specific ranges simply from the appearance of the discharge.

          • Kamal Lodaya says:

            OriginalJohn: Sorry, but that is not a prediction of your theory. As far as I can see nothing in the electric theory depends on whether ice is present on the comet or not. As I have said earlier I do not see why we cannot have two different mechanisms working on the comet. Nothing says that if one mechanism is active it will hinder the other one from happening.

    • ianw16 says:

      @Thomas;
      “So now we are being asked to believe that the water allegedly “spewing” from the surface is immediately dissociated into H and O atoms, before coming together to form water again further out in the coma. ”

      Who said that? Where have they detected it further out in the coma?
      The only claim I’ve seen that relates in any way to that is by an EU supporter, who claims that O- is being stripped from the surface and carried into the tail of the comet, where it is combining with H+ ions from the solar wind to form OH. It is this OH, he proposes, that the instruments are seeing, and mistaking for H2O.
      Wrong, they’re seeing actual H2O, close to the surface, and they are seeing it on the sunward side of the comet.
      Not even sure if an H+ ion at 400 km s^-1 could combine with an O- atom in the tail. However, that is irrelevant, as there are nowhere near enough protons to account for the observed H20 or even OH.

      • Harvey says:

        Ianw, you are quite right that recombination to form water molecules is extremely improbable under those conditions.
        There is no possibility whatever OH can be mistaken for H2O of course. Their electronic, vibrational and rotational spectra are utterly different. H2O is an asymmetric top, OH a linear molecule. Asymmetric tops have complex spectra with many lines in a complex pattern: linear molecules a simple so called ‘PQR’ structure. MIRO measured lines in H2O at 67P and Kuiper thirty years ago infrared lines of Halley I think it was.
        Whilst once the evidence of water, whilst extremely compelling, was indirect via the observation of OH, the direct confirmation has existed for decades.
        But as you say, there is not enough solar wind by many orders of magnitude. (Oh, and what happens to the silicon? And the massive power deposition it would represent? And then there is the very low sputter yield……..)

  • Kamal Lodaya says:

    Is this process enough to explain formation of an ion tail, or do the numbers not match up yet? The composition seems to be of the kind observed in spectra. Perhaps an incipient ion tail?

  • Harvey says:

    Kamal. It only forms properly when the bow shock forms, which depends on the degassing rate. The bow shock was predicted to have formed by now, but depends on the degassing rate. We’ve not seen any data on out gassing rates to compare to models, or from the Rosetta plasma probes which should clearly show if it’s now behind the shock or not. So the team knows, but we don’t 🙁
    Certainly the composition is pretty much as expected; the new element is the importance of the electron impact dissociation, the initial photoionisation step is as per models, Indeed it’s not obvious why this mechanism wasn’t already included, it’s not radical, just overlooked I guess.
    It’s currently quite badly position for earth based measurements of the ‘remote’ tail I think.

    • originalJohn says:

      I suggest Harvey that the imagined bow shock effect, whether a collision or a magnetic field effect would if it occurred be inconsequential compared to the pinch effect in the solar plasma current and other known behaviour of plasma.

      There is no evidence either that the origin of the constituents of the coma is degassing, ie release of gas. The spherical coma is probably a plasma with properties that no gas has. The team knows but we don’t.

      • Harvey says:

        As usual you just ignore inconvenient evidence.
        Several spacecraft have flow right through the bow shock and shown the unequivocal expected signature of it. Furthermore it’s completely expected from plasma physics (real plasma physics that is).
        A pinch would have a completely different signature .

        Molecular water was first detected thirty odd years ago from Kuiper, and measured by MIRO on Rosetta.
        Of course the coma is a plasma; a very tenuous one; that’s why there is a bow shock, ion tail etc. Is this supposed to be a surprise? There are hindreds of papers on it.

        • originalJohn says:

          And the unequivocal expected signature of a bow shock is Harvey ? Not one from magnetohydrodynamics either. That would be extremely equivocal. A dubious theory which is far from real plasma physics.
          Oh and the signature of a pinch is ,Harvey ? or a double layer boundary for that matter. Although I have given you some help on that elsewhere here.

          And yes, no argument about the demonstrated presence of molecular water. No evidence though of its origin.

          And I don’t think I suggested that the plasma nature of the coma was a novel idea. To you maybe but not to me, nor the numerous publications. Reading some of them would be a good idea.
          I realise that plasma physics is new to you and you have a bit of catching up to do.

  • J.H. says:

    So to reiterate what I think I’m reading in that…

    From the comets nucleus up to a kilometre there is an “photoionization of H2O molecules… An electron is released.

    Then at about a kilometre the density of electrons is enough to initiate electrolysis of the H2O molecules splitting them into Hydrogen and Oxygen.

    Thus at about a kilometre there is a “boundary” or a “surface” in which an electrified current is electrolysing H2O into Hydrogen and Oxygen.

    Is that why they are surprised?

    • Harvey says:

      Electrolysis is a mechanism that depends on the passage of current through a liquid containing ions, driven by an externally applied field. Generally no free electrons are involved, it’s all ions of both signs.
      There is no ‘current’ involved in the mechanisms described here in that sense. The electrons are moving randomly and diffusing, not moving consistently in an externally imposed drift field. It’s gas, not liquid, and electrons are very much involved, so very different indeed to electrolysis.

      The whole ‘surprise’ thing is over hyped. Basically they have realised that an extra detailed mechanism is important which had previously been overlooked. It’s an incremental improvement to the models, not a radical revision of them. The authors of course want to talk up the novelty a bit (yes, scientists do that :-). ) and others wish to hype it for effect.

  • THOMAS says:

    I quote from the article:

    “The team LIKENS the break-up of the molecules to the process that has been proposed for the plumes on Jupiter’s icy moon Europa, EXCEPT THAT the electrons at the comet are produced by solar photons, WHILE the electrons at Europa come from Jupiter’s magnetosphere.” (My capitals for emphasis)

    Could someone please explain how these two admittedly quite distinct processes can be “likened” (with all the relevant maths and equations, by all means, if they help us to understand the processes at work). In short, what is the possible relevance of this comparison in terms of correct scientific method?

    • Harvey says:

      It’s a passing comment that the same mechanism is thought to operate in the Europa plumes but with a different source of electrons. It has no great importance and they don’t give it any; but those interested might care to look up the Europa situation, so worth a brief mention.
      Basically, so what?

    • ianw16 says:

      The author of that paper has his e-mail address on the paper. Why don’t you e-mail him, laying out your qualifications, and respectfully ask him to explain?

  • Joe says:

    What proportion of the water vapour leaving the comet is split? If this is a significant proportion how does this impact the water-delivery model where Earth’s water may have been delivered by comets (ignoring for the moment whether specific invidividual comets have matching isotopic mixes)?

  • Harvey says:

    Joel can’t give a quantitative answer off the cuff, but almost certainly a small fraction of it due to the low density.
    It does not appear to impact the’water delivery to earth’ story in any way I can think of. That invokes sctual hard body collisions with earth, ‘bulk delivery’ 🙂

  • Robert Clark says:

    I’m trying to see if this amount of H and O available could be harvested for propellant for in-space propellant depots. This would have an advantage of just using the H2O in that you wouldn’t need the extra step to disassociate the H2O into separate H and O.
    Anyone know the amounts released?

    Bob Clark

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