VIRTIS detects water and carbon dioxide in comet’s coma

In previous blog posts we’ve heard how VIRTIS is able to map the temperature of the comet’s surface. Now, as Dominique Bockelee-Morvan (CNRS) and Stephane Erard (Observatoire de Paris) report, the VIRTIS science team has started to map gas in the coma.


VIRTIS spectra of Comet 67P/C-G's coma from early October 2014, showing water vapour and carbon dioxide. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; Comet image: ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0

One of the scientific objectives of Rosetta’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) is to map the emission of different gases from comet 67P/Churyumov-Gerasimenko, and to study how these change with comet activity.

In early October 2014, activity in the region above the ‘neck’ of the comet became high enough for water (H2O) and carbon dioxide (CO2) to be detected by the instrument’s high spectral resolution channel, VIRTIS-H. (The surface mapping is done with an imaging spectrometer, called VIRTIS-M.)

From these spectra, it is already possible to tell quite a lot about the gas in the coma.

The spectra show infrared molecular bands whose shape depends on the temperature in the coma, whereas the intensity is a function of the number of molecules along the line of sight of VIRTIS.

From these measurements, the relative abundance of carbon dioxide with respect to water is estimated to be about 4%, showing that comet 67P/C-G is not as rich in carbon dioxide as comet 103P/Hartley, also a Jupiter-family comet, for which a relative abundance of about 20% was measured by NASA’s EPOXI mission during its brief fly-by on 4 November 2010.

Ever since July, VIRTIS has been measuring the average temperature of the comet’s surface, finding it to be around –70 °C at the moment. These measurements of the gas in the coma now allow the science team to say something also about the temperature at some distance from the surface.

The current measurements correspond to a height of one kilometre above the surface, where the temperature falls by more than 100 °C to around –183°C. This large drop is expected, and is due to gases accelerating away from the surface and expanding in the coma, leading to cooling by so-called ‘adiabatic expansion’.

The detection of gases in the comet’s coma in this early phase of the mission is important for understanding the ices inside the comet. MIRO and ROSINA have already detected water and carbon dioxide, respectively, and VIRTIS can detect the same molecules, adding robustness to the measurements. But because it can see both with the same instrument, it can determine their relative abundance directly.

This is very important because from the ratios of these two molecules that make up the ice in the comet, scientists can gain vital insights into the make-up and structure of that ice. Ultimately, these new measurements will help meet one of the key goals of the Rosetta mission: what is comet 67P/C-G made of?

As the comet moves towards perihelion in August 2015, its activity will increase, and the team will be looking at how temperatures vary on the surface and in the coma. During this time, VIRTIS will continuously map the distribution of carbon dioxide and water, as well as that of other minor species including carbon monoxide (CO), methanol (CH3OH), methane (CH4), formaldehyde (CH2O), and hydrocarbons such as acetylene (C2H2), and ethane (C2H6).

There are exciting times ahead as the icy treasure chest starts to give up its secrets.



  • Jacob nielsen says:

    Relative abundances of substances in the coma can only be translated into relative abundances in the nucleus with some caution: repeated cycles of sublimation, (melting) and re-freezing, may cause substances to separate, facilitating sequential release to the coma as 67p approaches sun. The differential heating of the surface caused by suns radiation I believe is still fairly low and I think it has been mentioned that tidal forces is still the main motor in generating heat in the regions where e.g. H2O and CO2 are 'stored' (ignoring the more speculative explanations). Would be nice to see images of the surface with an infrared filter. (Am I the first one to ask for that? 🙂 )

    • THOMAS says:

      @Jacob Nielsen "Would be nice to see images of the surface with an infrared filter. (Am I the first one to ask for that?)

      There shouldn't really be any need to "ask" for those images, since they were promised as early ago as August 1, when the average temperature of -70C (measured even earlier "between 13 and 21 July" by Rosetta’s visible, infrared and thermal imaging spectrometer, VIRTIS) was first published:

      In that release, VIRTIS principal investigator Fabrizio Capaccioni explained that "very soon, VIRTIS will be able to start generating maps showing the temperature of individual features". Though having just reread what he said, it's true he didn't actually promise anything....

      One wonders why this ultra-important information in terms of revealing the temperature of all those (relatively) much whiter patches, particularly on the neck, has not yet been released. Too hot to handle for standard dirty snowball theory?

  • Perrier says:

    Water, Carbon dioxide. This comet seams to be a pretty good sparkling mineral water source 🙂

  • John says:

    Hello Claudia, would you explain how you are able to conclude that the water you have detected in the coma was sublimated from ice in the nucleus when it is recognised, and by NASA too, that rock bodies can interact with the solar proton stream to release oxygen ions which then combine with the protons (hydrogen ions) from the dense proton stream to form water. How can you be certain about the unique origin of the water from its presence alone.
    Also you have measured the surface temperature of the nucleus as -70 Celsius and that of the coma at a height of 1 kilometre as -183 Celsius and you say this drop results from heat lost by adiabatic expansion in the evolving gas. How then does the radiant heat from the Sun. the cause of the sublimation, get past the thermal trough in the coma and re-energise itself so that it gains the 113 degrees of temperature necessary to heat the surface of the nucleus to -70 degrees.
    It would be better to conclude from your measurements that regardless of the sensible heat in the radiation from the Sun there is an energetic reaction between the cold proton stream and the surface of the of the comet nucleus which heats that surface to -70 degrees. The anomalous temperature gradient in the come would.then be of no consequence.

    • Dave Harvey says:

      There is no such concept of a "thermal trough" for photons! To take a terrestrial example, If there were such an obstruction to photons, then you could not get sun-burnt when skiing, or perhaps more generally, we could have the earth heated by the sun to temperatures higher than the typical -70C found in the stratosphere!

      • John says:

        Good point Dave Harvey, presumably because the photons have little or nothing to collide with to release their energy. Plenty though in the the Earth's atmosphere and on the surface, including us.
        Plenty too in the comet's coma but they seem to fail to impart their heat until they reach the nucleus. That's the trough my friend.

    • Robin Sherman says:

      In todays Google+ Hangout Matt Taylor, the plasma guy on the Rosetta science team explained that the plasma in the comet's coma has a current induced it it by the comet's passage through the Sun's magnetic field. This current then generates its own magnetic field within the coma. This magnetic field deflects the Solar Wind around the comet, much as the Earth's magnetic field does. Very little of the Solar Wind even gets near the surface of the comet. No figures were given for the size of the current or the strength of the induced magnetic field. A graph showed it was variable, possibly in line with changing coma plasma density, and hence has a wave like structure of a higher and then slightly lower magnetic field strength. It does suggest the nearer the comet gets to the sun the stronger this magnetic field will become and even cosmic rays might not get through. Weathering is down to good old fashioned sun burn.

      • Sovereign Slave says:

        What specific scientific data did he refer to, from Rosetta or otherwise, to begin to validate this theory? Hopefully he was citing reams and reams of Rosetta data to back up what he was saying. Otherwise I'll slot this under the normal hubris shown by the standard model - it seems to inevitably state theories as absolute, consensus agreed upon, undeniable facts, no doubts, no discussion or consideration of competing theories, no walking through of the scientific method that made these conclusions self evident and validated. So again, until there's hard data released that can be reviewed and interpreted by a wide range of experts, there's no reason at all to put much stock in more opinions, EU crowd included.

        • Robin Sherman says:

          The video of the webcast is available to view just click on the hangout top right of this page. I should say this is not some theory made up, it is basic electromagnetism, a pillar I believe of the EU model and something predicted by it. A charged object, the comet's coma, moving through the Sun's magnetic field, in fact any charge moving through a magnetic field will generate an electric current. As it happens he did have data from Rosetta's instruments to base his explanation on.

          Electric currents flowing in a conductor generate a magnetic field. FACT. One that has been known since Sir Michael Faraday demonstrated this at the Royal Institution in London at the beginning of the 19th century. Now if 200 years of discussion, multiple applications, mathematical proofs, the computer used to write your post is powered by electricity generated using this basic Physics, is not enough to validate a model then perhaps you could explain why.

          • THOMAS says:

            Good post, Robin. Thanks for your reporting on this hang-out. (I didn't watch it because I expected nothing from it: I'm pleasantly surprised...).

            We're finally getting there! ("We" in the most general sense of all those who still fervently believe in the absolute precedence of observation over theory and that "ROSETTA" will indeed finally unlock one of the main secrets of how the Universe REALLY works ...).

          • Sovereign Slave says:

            Thanks for the pointer to the video, Robin. Nice to see that many people are watching it…it was at 301 earlier today, when I actually sat down to watch it later it was over 1500. And imagine my consternation at what seems a near role reversal as you lecture me on the dynamics of electricity and it’s behavior in space. Bravo! Matt did have interesting things to say about “how the comet and this gas out of the comet interacts with the solar wind, the outer atmosphere of the sun.” He goes on to talk about plasma instabilities that generate waves which create boundaries between the comet and the solar wind. He also mentions “plasma bubbles,” “plasma instabilities,” “plasma waves,” and other confusing terminology that seem to be labels that I think probably defies a clear definition of established electrical phenomena, similar to other references such as “magnetic reconnection” when referring to solar activity. Anyway, I did not hear him make any comments about weathering being from sunburn, or anything he said outright negating electric tooling however. I IS however very nice to see that electricity in space related to the comet is being discussed!

            One thing he said that really floored me was the volume of water entering the coma that the comet was generating. Right now it’s several kilos per second. And unless I misunderstood him, he said that this will increase to 100’s of kilos a second as the comets activity increases through perihelion! Now, I’m American, so to get a sense of how much this is, I first converted kilos to gallons. I’m going out on a limb here, so let me know if I messed up the conversions and this line of reasoning anywhere, but to be conservative, I’ll use 200 kilos for his “hundreds,” which is almost 53 gallons. So let’s go with 50 gallons. So at its most active, that’s (very conservatively) at least 50 gallons of water coming off the comet EVERY SECOND. That’s 3000 gallons per minute; 180,000 gallons per hour; 4,320,000 gallons each 24 hours (or every day); basically 130,000,000 gallons per month. That’s a vast amount of water!

            To put this into some kind of perspective, I looked it up and found that a pool with one million gallons of water in it would measure 267’ long, 50’ wide, and 10’ deep. The comet produces over 4 million gallons a day, so to fit this into a manageable visual, let’s say that each day’s sublimated ice again very conservatively produces one football field’s worth of coma water at a depth of 10’ per day (a football field is 160’ wide by 300’ long). Each day would add 10’ to the depth of the pool then. The comet will be most active several months as it rounds the sun, let’s say conservatively 4. That’s basically 500 million gallons of water! And that’s not counting all the other ongoing sublimation taking place the other months. So going back to our football sized pool, that would be a depth of 1200’ (120 days x 10’). Or a pool that’s 10’ deep and roughly 2 miles wide and 3 miles long. I’ve got no idea what percentage of volume this represents compared to P67, but seems like it would be quite significant.

            Since discovery in 1969, P67 has gone around the sun 7 times. That’s very conservatively 3.5 trillion gallons worth of sublimated ice.

            So no wonder there’s still hoping for ice. Standard theory dictates that all the water found in the coma comes from sublimated ice found on (well, now in) the comet. And a massive amount of ice is necessary for the sublimation theory to hold true. Right now we’re facing a comet with NO surface ice to speak of, in fact its apparently bone dry.

            As stated, EU theory requires no cometary ice to create water in the coma, just a bone dry rock with a disparate charge to that of the sun.

      • THOMAS says:

        Sounds like a start to the beginning of a very unwilling sort of admission as to the faint possibility of an electromagnetic component to cometary activity....

        It's a beginning. More will follow.

        • Jacob nielsen says:

          @Thomas, no news in the role of electromagnetism in shaping the coma. Electricity as such is not a secret and not excludive to EU. I guess the showdown is between sublimation as a product of solar and tidal heating vs. Electric corrosion producing ions reacting to produce the observed water. I am having my fun now, maybe you will have yours later 🙂

      • John says:

        It is odd how this theory you convey makes no mention of the comet nucleus in the current flow and no mention of the current flowing in and from the Sun which is responsible for the Sun's magnetic field. It seems to suggest that the plasma in the coma exists as a spherical shell in isolation, with no association with the comet nucleus other than as a source of neutral gas from which the plasma formed by ionisation.
        In which case the question arises what keeps the nucleus at the centre of the coma, or even in it at all. There is no reason why they should not drift apart and go their separate ways. The gravity of this comet is as we know vanishingly small and the coma could easily span several thousands of kilometres. Impossible for the tiny comet to exert a gravitational influence over that distance. A plausible theory should link the plasma current in the coma to the comet nucleus then they could be considered as an entity. Perhaps we should wait for some actual measurements. A nice plasma map of the coma would be useful.

    • AndreH says:

      @John: "Also you have measured the surface temperature of the nucleus as -70 Celsius and that of the coma at a height of 1 kilometre as -183 Celsius and you say this drop results from heat lost by adiabatic expansion in the evolving gas. How then does the radiant heat from the Sun. the cause of the sublimation, get past the thermal trough in the coma and re-energise itself so that it gains the 113 degrees of temperature necessary to heat the surface of the nucleus to -70 degrees." Just like on a sunny day the sunlight passes through the air which may have a temperature of 30°C and heats up an asphalt road up to 50° C or more. No "reenergizing" needed.

      • John says:

        Well AndreH, the conditions at the comet are nothing like those on the surface of the Earth on a sunny day. Trough or not you seem happy that the feeble sunlight at 400 million kilometres plus could maintain a temperature difference of 113 degrees between the comet surface and its surroundings with the major losses that would occur, including the loss from the theorised expansion of the theorised gas from the theorise vents. A much more concentrated source of energy would be required like for example the heat by- product of proton sputtering of the rock,

  • John says:

    * coma

  • Don says:

    Interesting info on composition of a comet.

  • Prof Harvey Rutt says:

    The sun's radiation has no problem 'getting past the thermal trough' do it does not have to 're-energise' itself, though it's not clear what that means.
    Cold, low pressure CO2 and H2O have very narrow, discrete absorption lines. In between those lines the radiation simply passes straight through the gas without interacting with it.
    Most of the sun's radiation is in any case at much shorter wavelengths, where the molecular species have extremely low absorption.
    Re protons generating water, not my field, sounds possible, but I suspect would generate far too little water to generate these effects by a very large number indeed. It could also only explain water from areas directly illuminated by the solar wind, which is clearly not the case.

    • John says:

      As with the "greenhouse effect" too Prof ?
      The solar wind is a stream of ions which can interact with the whole surface of the comet, day and night side. This has been observed in other comets and probably will be in this one too.

      • Prof Harvey Rutt says:

        Essentially as in the greenhouse effect, but the details are different. On Earth the absorption lines are pressure broadened and Lorenzian in shape, decaying slowly with spectral distance from the absorbing line. At these very low pressures the lines will be Doppler broadened, Gaussian in shape, and reduce very quickly. This will in fact make it easier for the sunlight to mainly 'shine through' the CO2 spectrum.
        I don't doubt the mechanism exists; I seriously doubt it is anywhere near strong enough to explain what is seen.

  • Robin Sherman says:

    Thanks Claudia, you know how some of us like our science treats. So there is 25 times as much Water in the Coma as Carbon Dioxide. Last info we had on the amount of water leaving the comet was from way back in August at a maximum of 5 Litres per second. Some of us are sure we have seen increasing amounts of sublimation in the form of gas plumes and dusty jets. If we have seen it in the lower resolution images released here, then the science team must have access to better images to validate the sublimation process that is going on. Any news on how the recent rise in sublimation activity seen in the NAVCAM images, has increased this figure? Is the density of the gases in the Coma yet at a level sufficient to affect the amount of Solar radiation reaching the surface. Visually I would imagine not, its still little more than a diffuse haze.

    • Robin Sherman says:

      HI Claudia. Just watched the hangout and there was a graph of coma density on that, no figures to tell us what that density is, but we can see that it does fluctuate in a diurnal rhythm with the rotation of the comet. This is at least evidence that the coma gas density is related to the amount of sunlight reaching the surface below Rosetta and suggests sublimation from the surface is creating the coma. Hopefully this information and graph will shortly be available for us to peruse at our leisure along with the plasma interaction information.

  • Cometstalker says:

    So we now can confirm that it is possible to detect water and carbon dioxide and that those compositions are present in the coma. I would rather like to see a graph of how the quantity is varying in time. And also an infrared scan of the surface overlaid on a photographic image of the streamers would be nice.
    The science is not at an overwhelming level of what is presented so far, i guess we will continue to stick with fiction as there is no alternative. To present that the instruments are working is fine and to use the capacity of skilled personal to add up a few simple things to a meaningful conclusion would be magnitudes better. So far all we get is in the (de)range of the colorized image of the comet that was called a map and was nothing but a meaningless poster good for nothing.

  • dave says:

    Proff Harvey Rutt
    Here is an extract from a paper ref some lab experiments done back in the 70's, showing how the solar wind will produce water when there are silcates on the surface being eroded.
    We know there are silicates on this comet from the capture of dust, so we might expect this method of comet erosion to be happening right now in front of us. Especially since there appears to be a complete absence or Ice on the surface of the comet.

    Here is an interesting NASA article in which it is conceded that the presence of the hydroxyl radical in the coma does not necessarily imply the existence of water on comets. ''14.6. INFERENCES ON THE NATURE OF COMETS FROM EMISSION CHARACTERISTICS

    The assumption of ices as important bonding materials in cometary nuclei rests in almost all cases on indirect evidence, specifically the observation of atomic hydrogen (Lyman [Greek letter] alpha emission) and hydroxyl radical in a vast cloud surrounding the comet, in some cases accompanied by observation of H20+ or neutral water molecules. In addition, CH3CN, HCN, and corresponding radicals and ions are common constituents of the cometary gas envelope. These observations can be rationalized by assuming (Delsemme, 1972; Mendis, 1973) that the cometary nuclei consist of loose agglomerates containing, in addition to silicates (observed by infrared spectrometry (Maas et al., 1970)) and also water ice with inclusions of volatile carbon and nitrogen compounds.

    It has been suggested by Lal (1972b) that the Lyman a emission could be caused by solar wind hydrogen, thermalized on the particles in the dust cloud surrounding the comet. Experiments by Arrhenius and Andersen (1973) irradiating calcium aluminosilicate (anorthite) surfaces with protons in the 10-keV range resulted in a substantial (~10 percent) yield of hydroxyl ion and also hydroxyl ion complexes such as CaOH.

    Observations on the lunar surface (Hapke et al., 1970; Epstein and Taylor, 1970, 1972) also demonstrate that such proton-assisted abstraction of oxygen (preferentially O16) from silicates is an active process in space, resulting in a flux of OH and related species. In cometary particle streams, new silicate surfaces would relatively frequently be exposed by fracture and fusion at grain collision. The production of hydroxyl radicals and ions would in this case not be rate-limited by surface saturation to the same extent as on the Moon(for lunar soil turnover rate, see Arrhenius et al. (1972)).

    These observations, although not negating the possible occurrence of water ice in cometary nuclei, point also to refractory sources of the actually observed hydrogen and hydroxyl. Solar protons as well as the products of their reaction with silicate oxygen would interact with any solid carbon and nitrogen compounds characteristic of carbonaceous chondrites to yield volatile carbon and nitrogen radicals such as observed in comets. Phenomena such as "flares," "breakups," "high-velocity jets," and nongravitational [236] acceleration are all phenomena that fit well into a theory ascribing them to the evaporation of frozen volatiles. However, with different semantic labels the underlying observations would also seem to be interpretable as manifestations of the focusing and dispersion processes in the cometary region of the meteor stream, accompanied by solar wind interaction.''

    What do you think guys?

    • Marco says:

      Hi Dave,
      I, for one, don't buy it. Yes- There is interaction with the sun in some of the ways described. However what is happening inside the comet is more important to what makes a comet. And it is not a simple scalable, experimentable phenomenon. It is a complex thing that we need to get inside the comet ( or at least look inside, via CONSERT) to get to the bottom of.

      • THOMAS says:

        Looking forward to the CONSERT findings, though still doubtful of Philae's ability to live long enough on the surface (if it manages to reach it with all systems working) to acquire and transmit them.

        If it does manage to, the difference will be totally unambiguous between an overall rocky composition (with possible fissures and cavities as in rock formations down here on Earth) or, on the other hand, a hollow or ice-filled interior beneath the evident rocky crust.

        And the argument between the competing models will be settled beyond the shadow of a doubt.

        Can't wait for Wednesday evening!

  • logan says:

    Thanks a lot Claudia, Dominique and Stephane. This 4% C02/H20 snippet of data changes all of my panorama about relative density of structures. Much less minerals than those on my initial scenarios. Slower sublimation /deposition. More of a chance for 'complex' organic. Etc.

    Discourse 'changing'. 🙂

  • THOMAS says:

    An average temperature of -70 C seems extraordinarily high given that it was measured back in mid-July when 67P was still at a distance from the Sun of well over twice that of Mars, where the average temperature is measured at -60 C. It was still considerably closer to Jupiter than to Mars, the temperature of the Jovian clouds being estimated -145 C… There is thus something clearly abnormal about 67P’s temperature as it is situated on the expected temperature gradient/distance from the Sun.

    The extra heat is estimated by VIRTIS mission scientists themselves to be an amazing “20 – 30 C” higher than expected or predicted by standard theory, and cannot simply be due to the photons received from the Sun. An internal heat source seems to be ruled out in such a tiny body which is supposed to have been in existence since the beginning of the Solar System.

    The EU model, on the other hand, PREDICTS a higher-than-expected overall average temperature due to the extreme heat created LOCALLY by the occurrence of ongoing electric discharge machining, preferentially on prominent surfaces. This locally generated heat explains the lava-like smooth plains to be seen all over the surface and currently corresponds to the whiter spots and patches to be seen on all the images we have received. Confirmation of the much higher temperature of these local hot-spots could easily be provided (and presumably already has been) by the VIRTIS infrared cameras. VIRTIS principal investigator Fabrizio Capaccioni was understandably proud to be able to assert, even before Rosetta arrived at the comet back in July that "very soon, VIRTIS will be able to start generating maps showing the temperature of individual features".

    I see no reason why those “maps” should not now be released for public viewing. If there turned out to be absolutely no measurable local temperature differences, this would, in my opinion, seriously challenge the EU comet model.

    Why is this essential information being withheld?

    • Marco says:

      Hi Thomas, given that the average temperature is so high - I think that any explanation or eventually discovered reason would indicate local temperature differences. There are other competing models, hardly mentioned in the comments - one main one being the "wet comet" model promoted by panspermia advocates, which hypothesises a phase change from the dirty snowball to a liquid water filled, partially pressure sealed comet with active bacterial life within. "Respiration", that is the conversion of chemical energy to waste heat and compounds would drive both the jets and the increased temperature at this point in the orbit. There are other theories and variations, so rightly dismissing naive snowball theory does not necessarily elevate EU.

    • Mar'ya says:

      Hi Thomas,
      sorry for a possibly silly question but what is the EU comet model?

  • logan says:

    'Something' is published today at Imgur.

    Need some redundancy on this.

  • logan says:

    Could it be that 67P has depleted most of her CO2?

    • Robin Sherman says:

      Carbon Dioxide is heavier than Water, so if the porous nature of the comet allows migration of molecules, the Carbon Dioxide will sit below the Water. We are at the initial stages of sublimation so the water being nearer the surface sublimates first and there is a lot more of it. As activity increases this ratio might change, hence the interest in studying how this ratio changes with time to understand the composition of the comet. Carbon Dioxide is less reactive than Water, consequently there tends to be a great deal of it knocking about the Solar System.

      • Cometstalker says:

        Carbon dioxide ice is a bit heavier then di-hydrogen monoxide ice, about a factor 1.5/0.9 although this is not essential. The lighter elements that can freeze in this environment is mixed to a cocktail, say H2O:CO2:CO:NH3:CH4:CH3OH:HCN:And a lot more soaked up by the dust-grain structure.
        To determine the sublimation point in almost vacuum of this mess is not easy and whatever decides to leave the bonding will also pull other compositions with it.
        I would like to compare it to what is going on when a still is filled with water and roses to get access to the complex composition of the fragrant rose oil that has a boiling temperature a lot higher than water. The steam pulls the fragrace with it and when it condenses to water a fraction of rose oil is separating out by flotation.

  • Dave says:

    That's a new one on me, it made me smile though, at least the electric scouring of the surface is tested in the lab by NASA of all people. Maybe you can argue that it is not scalable but for sure it's happening, maybe you could argue it does not generate enough water but that would ignore the fact that the solar wind can supply hydrogen to convert the oxygen in the coma to water.
    Is there is any link you can supply ref the super wet comet you have described, I would be interested to have a look. All the comets we have seen appear to be bone dry.'

    • Marco says:

      Hi Dave, Thomas,
      The following link is to research by, among others, Richard B Hoover, a former NASA astrobiologist and enthusiast for the model.

      The link didn't work for me on Chrome, but it did on Safari. Just in case I included the Abstract below:
      ABSTRACT:It has been seven years since we presented evidence for liquid water on comets and the wet comet theory that comets melt and undergo an irreversible phase change on their first passage through the inner solar system. Since then there have been three more comet flybys and analysis on returned cometary material. We review the wet comet model and discuss the new data, showing that the model not only has been further vindicated, but explains several more independent observations. Not only do comets show evidence of some melting, they show evidence of complete melting.

  • Dave says:

    Hi rob,
    At least we admit there is a current! Now we just have to find birkeland currents that would be acting to equalise the potential between the comet and the local potential in the solar wind. The difference in potential may well get bigger as it gets nearer the sun hence the birkeland current may get easier to see as the plasma discharge begins to glow, rather than just be witnessed by the dust caught in the magnetic fields surrounding the birkeland currents. Once this is confirmed it would be game over for the std model.
    If there are ices somewhere on the comet then clearly with the correct conditions then sublimation may occur but on such a dry structure it does not look to me that it could be the main driver of the jets(no ice has yet been detected)

  • THOMAS says:

    Sure, Marco, it's true I'm perhaps a little too focused on the dominant "dirty snowball" v. EU opposition. It's true I know very little about the other alternative models. And I've always made it a personal rule not to make assertions on things I know nothing about.

    • Marco says:

      Hi Thomas,
      I do encourage you to read the link regarding wet comet theory - Not because I think you will at all be convinced by it, but that it is important not to get caught up in a false dichotomy. I do think that the one thing that the dirty snowball idea has going for it is that there is strong scientific evidence that there was such objects very early in the solar system's foundation. Evidence seems to show that there is not now. The thing that EU has got going for it is that there does seem to be considerable electromagnetic interaction between the sun and it's orbiting bodies. Both models have some solid science behind them, but both models by themselves are way too simplistic to accurately describe what is happening now on comets. Ockham's razor has been applied too hastily on them.

    • Andrew R Brown says:

      Is that so Harry Costas using the sock puppet Thomas, who has been banned from every serious science board.

      • THOMAS says:

        Hi, Andrew R Brown, welcome to the blog. Many thanks for your attempt to get me banned by the moderators. Well tried! But I doubt if it will be enough…

        Are my posts THAT threatening for the standard theory you seem to be so worried to defend? I must admit to feeling quite flattered.

        I’ve absolutely no idea who “Harry Costas” is. What entitles you to cast any doubt on my real identity anyway? And who are YOU, by the way?

        I’ve lived in France for the past 33 years. Has Harry Costas? To dispel any possible doubt, I’m translating this post into French, which I write and speak fluently. “Harry Costas" presumably doesn’t!

        Salut, Andrew R Brown, bienvenue sur le blog. Grand merci pour votre tentative de faire bloquer mes commentaires par les modérateurs. Bien joué ! Mais cela ne suffira sans doute pas…

        Mes commentaires sont-ils vraiment si menaçants que cela pour la théorie standard que vous défendez ? Je dois avouer trouver cela plutôt flatteur.

        Je n’ai pas la moindre idée de qui est “Harry Costas”. Qu’est ce qui vous donne le droit de mettre en doute la réalité de mon identité, déjà ? Et vous êtes qui, vous, au fait ?

        Je vis en France depuis 33 ans. Tout comme Harry Costas, sans doute? Pour qu’il ne subsiste aucun doute à ce sujet, voici ma traduction de ce commentaire en français, langue que je maîtrise aussi bien à l’oral qu’à l’écrit. Je suppose que l’on ne peut pas en dire autant de “Harry Costas"...

        • Marco says:

          Please don't ban Thomas. We want him to be here long enough for him to eat his words regarding the "rock"
          I am thinking any of the following are more likely.
          Crude oil, tar, vulcanised rubber, liquorice, coal, graphene aerogel, black petroleum jelly, "shoe polish" - ie. materials made from complex mixtures of organic compounds that are black.

          • THOMAS says:

            Thanks for your plea in my favour, Marco, even if I sense a certain irony in it. It wasn't needed anyway. My rejoinder to Andrew R Brown (whoever HE is) was willingly accepted by the moderators. (See above).

            Talking about rock and rocky outcrops, I just came across the most spectacular example of it yet in this image published some days ago on the ESA “Space in Images” page (not sure if it’s been published in any of the blog posts):
            It’s so obviously rocky, with dead straight seams of stratified rock over hundreds of metres, deeply fractured in many places, perpendicularly to the main stratification. The most striking feature, however, is the completely free-standing mountain just left of centre, which which is utterly scarred both vertical stratification and horizontal fracturing, and hundreds or thousands of boulders lying on the two long flat terraces just above and below it. If this image had been acquired in ANY OTHER context, on whatever planet or moon we have obtained close-up images of, (and thus without the theoretical presuppositions and prejudices which are still blinding the majority of posters and visitors to this blog as to the true GEO-PHYSICAL nature of “comets”, despite all this observational evidence) then NOBODY would have had the least doubt that this is indeed spectacularly rocky rock we’re looking at.

            Marco, I sincerely believe you’ll soon be eating your liquorice and drinking your water, well before I start eating that rock.

  • Cometstalker says:
    The solar wind is often noted in the blog and i would like to add my cheese.
    It is mainly protons due to stripped hydrogen then there is about 8% @ particles due to stripped Helium add a bit of the traces in the graph in the link plus a lot of electrons and thats it. Then the speed has two fractions of flow, one makes it with about 400km/s and another twice that much. A lot of other stuff makes it even more complex but it is essential to realize that the sun releases positive charges as well as negative charges meaning electrons and charged atom nuclei. It is not a unipolar current. Only releasing positive charged protons. Although the huge difference of the mass between electrons and nuclei of atoms make the total effect quite complex when it hits the comet and its coma, creating currents in plasma and inducing magnetic fields plus some amount of electrostatic forces as well in this complex dance.
    We do not yet understand all of the complexity of our close by earth magnetosphere behavior that has been explored for several decades with a lot of missions ranging from balloons to arrays of satellites in orbit.

    In sum do not expect a lot from ESA as they so far release just about nothing of essence and the best we are getting are pictures that are crippled in their contents.

  • Cometstalker says:

    The icy treasure chest is quite empty with all the amounts of water expected and longed for in a manic almost psychotic way leaving a lot of dust and frustration to those people that suggested that our oceans are the result of colliding comets with earth. This is getting a bit tragicomical and possibly we should start to look for more interesting stuff like the solid minerals and their compositions and creations. I think this comet will soon become an asteroid. In desperation it is mentioned that its activity will increas a lot and those spectacular jets and streamers will become Hollywood shaped as soon the comet reaches perihelion. The hope lasts to the very end only outlived by the very conservative stubborn minds. So far the fiction is at its highest peak and I see no trace of the science that ESA is supposed to convert to. This really is a small backward step for homo sapiens and a giant forward leap for homo narrans.

    • THOMAS says:

      @Cometstalker: "I think this comet will soon become an asteroid."

      It will IMMEDIATELY become an asteroid if some inexplicable event occurs to circularize its orbit, since in that case all electrical imbalance relative to the solar electric field will be reduced to near zero. And that will mean no further discharge activity.

      It is more often the case that asteroids become comets, (or intermediate-type Centaurs) when something presumably happens to knock/pull/push/tweak them into a more elliptical orbit.

  • Lothair Hamann says:

    Was it actually h2o detected or just hydroxyl groups OH which could be produced in other ways and might not indicate water. Proton bombardment from the solar wind might play a part. Highly sceptical of the icey body theory with the whole frost line scenario even more so looking at 67p. Let's see if electrical discharge doesn't effect Philae moments before landing. I'm hoping not and that a certain amount of electrical equilibration after sharing part of the orbit cycle has taken place to neutralise this potential threat for the mission after what we saw with vesta. Fantastic mission thus far but sadly I think the whole pushing of one theory in the media spotlight when other ones which exist that seem technically more science based is a bit off putting from the main stream. This mission might at least over turn the status quo of dirty snow balls.

  • Dave says:

    Hi Logan,
    Keep the graphene aerogel hidden or we will all need a new theory.

    Maybe 67P really does walk on water after all,

  • Prof Harvey Rutt says:

    If the solar wind is responsible, acting on silicates, why don't we see this all happening on the moon, with a grandstand view? It's certainly made of silicate rocks, and has no atmosphere or magnetic field to protect it, and is considerably closer to the sun than 67P right now.
    The mechanism exists, but doesn't fit the behaviour, and is orders of magnitude too weak.

  • Prof Harvey Rutt says:

    Some level of discharge activity seems a possibility.
    But if it were occurring on s large scale, it out to be blindingly obvious. There would be a lot of atoms and molecular excited species emitting light, both neutral and ionised. It should be obviously glowing, at least in patches. There should be a lot of electrical noise, which might well have been detected too.
    Maybe it happens locally on a small scale, I've not tried to do any sums. But there is no observational evidence supporting it on a large scale.

  • Prof Harvey Rutt says:

    Ok, nasty cold wet day, stuck in a small flat, so I did some rough sums. Using rough and ready 1AU average proton velocities and densities, (~~500km/sec and ~~10/cm^3) and scaling to 67P current distance quadratically, there are several orders of magnitude too few protons available to explain the observed water degassing rate.
    Now I had to do much of it in my head, from web sources, I could have slipped up, but perhaps one of the protagonists would like to prove me wrong; *numerically.*

    • John says:

      It is not an observed water degassing rate Prof. It is a calculated rate of production of water or hydroxyl ions in the coma based on local analysis, with the assumption that they originated from water in the nucleus.

      I expect when you worked it out in your head you assumed an approximate cross sectional area of the nucleus interacting with the proton stream. Combination with oxygen ions can and does occur throughout the coma which can be thousands or even tens of thousands of times greater in diameter than the nucleus. Perhaps this is where your missing orders of magnitude are.

      Whether you can believe it or not the proton sputtering of silicates and subsequent water production is an effect observed and documented by NASA on solar system bodies. Others in this blog have provided references.

      • Prof Harvey Rutt says:

        I believe protons sputter silicate and liberate some tiny amount of oxygen.
        But not enough, by many orders of magnitude.
        Nothing in the NASA papers etc challenges that.
        As I've said repeatedly, the mechanism exists; but it's FAR too weak.

  • Can someone direct me to any discussion of the rubble field on the surface of 67P and its possible connection to envisioned formative processes?

  • Luke Collie says:

    Also from web sources, but on a calculator:-

    Proton flux at Earth = 3 X 10^8 per cm^2 per second

    The comet is now at 3 AU from the Sun, so the flux will be lower by a factor of 3^2 = 9

    The comet area exposed to the Sun if roughly a 3 km by 4 km elipse, area (1/4)*PI * 3 *4*10^10 cm^2

    So protons hitting the comet is ((3*10^8)/9)*(1/4)*PI*3 *4*10^10 per second = PI * 10^18/sec

    Three billion billion/sec sounds like a lot, but protons are very small. To get a reasonable mass of atomic-scale things, we need to count in moles, 6*10^23 protons = 1 mole of protons makes 1 gramme. So the protons hitting Rosetta are only (3 *10^18) / (6*10^23) = 5 *10^-6 moles per second.

    If all these protons were converted to water on hitting the surface, they would make 2.5 * 10^-6 moles of water. Al mole of water is 18 g, so that is 4.5 * 10^-5 g. Round up and call it 50 microgrammes per second.

    Rosetta has detected about 5 kg/sec of water leaving 67P, so the solar wind is about 100 million times too thin to supply the necessary hydrogen.

    This is all back-of-envelope work, of course. but I could be off a million fold and it still wouldn't work.

    Space is unimaginably empty. A good laboratory vacuum for most purposes - e.g. inside an electron microscope - is about 1 billionth of atmospheric. But such a 'vacuum' still has something like 10 billion times as many atoms in each cm^3 as there are solar wind protons per cm^3 near 67P, The environment is completely dominated by the outgasing from the comet.

    • Prof Harvey Rutt says:

      That is precisely the calculation I did; somehow, in my head I got a couple of orders bigger, but same conclusion; FAR too low.
      Somewhere higher up it was suggested the interaction area is bigger than the comet. There is no basis for that, it will just be its projected area; they have to hit silicate for the proposed mechanism.
      In fact the yield will be far less than the 100% we both assumes. Many will remain surface implanted, or escape other than as H2O.
      Basically, stop defending the indefensible; the mechanism exists; but is many orders of magnitude too weak.

    • dave says:

      See Johns blog above yours, it may help.

      Also No Ice has been found on the comet, so where do you suppose the water is comming from?

    • logan says:

      May the force be with you, Luke. Thanks for the calcs. 😉

  • Prof Harvey Rutt says:

    Perhaps we could think about ". Combination with oxygen ions can and does occur throughout the coma which can be thousands or even tens of thousands of times greater in diameter than the nucleus. Perhaps this is where your missing orders of magnitude are." a little.

    No reference, no mechanism, no numbers.

    If they are combining out there, how do they magically reappear right in close to the comet, where the outflows are being measured? Do they have some sort of homing instinct?
    Where are all these oxygen ions and atoms coming from; apparently not from degassing, since this mechanism is supposed to replace that; so what is their source? Proton impact? - but there aren't enough protons by far.
    And how does a 1 to 10keV proton combine with an oxygen atom or ion to form a molecule with a dissociation energy of about 4.8eV and satisfy minor matters like conservation of energy and momentum?
    (Yes, you will see some excited OH etc - from protons hitting degasses H2O! We can detect such things extremely sensitively.)
    The hypothesis does not stand up to a moments serious consideration, as soon as you require numbers, detailed mechanisms, it falls apart everywhere.
    There is much going on we don't understand; much to learn. But I'd place a large bet this is not a significant mechanism.

    • John says:

      Place your bet Prof and start doing the numbers on the ice sublimation mechanism, when some ice is found. Multiple assumptions in your calculations.

  • Prof Harvey Rutt says:

    Which assumptions would reduce the amount of water; and please state your case *NUMERICALLY*; *QUANTITATIVELY*. The assumptions made by Luke and myself *EXAGERATE' the amount of water produced by this mechanism, if anything. You need to find many orders of magnitude to overturn that calculation. In formulae and numbers, not words.

    Have you ever walked on a high altitude glacier? I have, many times. You are standing on maybe 100m or more of ice - and it's completely invisible under a thin top layer of debris. That's all it takes to hide the ice from direct observation, a thin layer of pretty much anything.

    Why isn't this happening on the Moon? It should be blindingly obvious!

    • dave says:

      Ok Prof Harvey Butt,

      We believe this method does not look substantial enough, but you are a betting man by the look of it so what is your bet?

      • Marco says:

        For what it's worth, I'm with the prof on this one. It is indifensible to claim that sublimating ice *on* the surface explains the emissions. It is equally indifensible to claim that solely electrical processes quantitatively explain the emissions. We are left with all the really interesting, complex stuff happening below the surface, and the sensible, logical, incumbent model being wrong enough that it should be dropped, while a popular alternative is quantitatively indefensible. The rediculous insistence that EU model is sufficient to explain everything is unnecessary

    • John says:

      You are not in academia Prof. This is where there are comments and a calm exchange of views. If you are not interested in words you are in the wrong place.

      I am not trying to prove anything. I am speculating on the origin of water in the coma reported in this ViRTIS result because I don't believe the ice sublimation story, for which there is no evidence so far on this mission or any previous comet mission. You clearly do believe it and you seem to want to negate the possibility of any alternative.

      ESA do not report any estimated quantity of water in the coma in this result just the abundance with respect to carbon dioxide. So the surface reaction remains feasible as an explanation of its presence.

      Results from other comet investigations have estimated large amounts of water in the coma, also without any confirmation of ice in the nucleus. So I am interested in the possibility of an in situ origin. The protons seem a reasonable source of the hydrogen element and this is not of course my original idea but I am supporting it. I am sure you are correct in your judgement that it is not energetically possible for hydroxyl ions to form under the conditions you assume. This does not, however, make ice which is hypothesised within the nucleus any more likely as the origin of the water that is there. The little understood environment within the coma is probably extremely complex and I am prepared to allow for the possibility of seemingly unlikely reactions there.

      You keep saying why doesn't it happen on the Moon, with regard to water production from silicates by proton sputtering. It does and has been reported. Look it up. That's what the search engines are for.

      Obviously further data is imminent and I await it with great interest. I will tell you now that my belief is that this comet is a negatively charged lump of igneous rock with an origin within the solar system. I presume yours is that it is a lump of ice and dust of primordial origin so let us wait and see which of us is nearer to the truth.

  • Prof Harvey Rutt says:

    'Belief' is completely irrelevant. That's to do with religion, not science. Science is to do with observations, deductions, analysis, and in particular *numbers*. It requires self consistency and accuracy. The replies on this are invariably totally devoid of *numbers* or any sort of quantitative analysis. When it is pointed out that a counter argument doesn't work, that gets ignored., as has happened repeatedly.

    What is going on inside the commet and what it's made of I have no evidence of directly; except that it clearly has a very low density, and any model needs to account for that; which rules out solid rock. It's degassing a lot of water and co2; the estimates of how much make no assumption about the source; the are from observed pressures, distributions and temperatures. Any model has to explain them, or prove they are wrong. Prove, not spout hot air. The obvious one is that under that black surface, there must be ice and solid co2.

    Talk of 'bi layers' etc is frankly nonsense; they are relevant on a few nanometer scale in lipid bi layers; there is no electrical force which could cause the miscalculation of the mass, yet permit accurate navigation by Rosetta.

    What I can calculate, with considerable confidence, is an upper limit to the proton arrival rate. That gives me, under the extremely 'optimistic' assumption that they all end up in water, an upper limit to this mechanism's water production rate; and it is far, far too low. You have done nothing to refute those estimates, other than make unsupported assertions, many of which are simply not physically credible.

    Oh, for the umpteenth time, *why isn't the moon degassing water like crazy*, the proton flux is ~~9 times higher, and we know there is plenty of rock.

    Whether 'dirty snowball' is a good description I don't know; not a term I've ever used.

    What I do know is that the proton flux *cannot* explain these degassing rates, and that there is no known mechanism which would confound the density estimate.

    • John says:

      Believe means accept in this context Prof. Nothing to do with faith.

    • Luke says:

      OK, same calculation for the Moon.

      Radius of Moon = 1738 km, so area intercepting the solar wind = PI * 1738^2 = 9.5 million km^2 = 9.5 * 10^16 cm^2

      Proton flux = 3 * 10^8 protons/cm^2/sec, as in previous post

      So 2.8 * 10^25 protons/sec

      Divide by 6 * 10^23 to get moles, and it is 47 moles/sec, enough to make 23.6 moles/sec of water, which is 425 g Call it half a litre/sec, or a pint if you prefer.

      That rate of water loss from the Moon should be detectable, but that only shows that the mechanism is not 100% efficient. It can generate some water, and probably does, see

      what littler water the Moon has is probably from this mechanism.

      • Prof Harvey Rutt says:

        Thanks for taking the trouble to do that.
        Results as expected; happens but tiny.
        I wonder if it has ever been detected directly? The resultant density in the vapour phase would be extremely low. Probably has in the solid.
        I'm still in my Japanese flat; when I get back home I'll run SRIM/TRIM and take a look at typical penetration depths just out of idle interest.

  • Dave says:

    Prof Harvey rutt
    Every person on this blog has the same problem. There is very little starting information to try any science. It's like the old joke,
    A tourist lost in an unfamiliar country stops and asks a local the directions to Utopia, the stranger replies if I was going to Utopia I wouldn't start from here.
    We don't even know what the comets made of yet, there is barely anything to start with.
    We are in limbo playing in a sand box, we can't get out again until there is more information.
    We probably all could knock over opposing views on the blog precisely because there is not enough information to make a descision.
    So you need to take your best punt, take a guess. It does not need to be perfectly backed by science, no one will take offence if you go with the original dirty snow ball or even the hard crust filled with pressurised water theory. Please feel free, place your bet and have some fun

  • Dave says:

    The comet is so varied in landscape I woul think that almost no body is thinking there is one model that explains it all.
    So the more the merrier

    • Marco says:

      Yes!! There are tantalising hints of things in comets like liquid water, complex organics, changes in spin rates.

      That together with knowing about other comets that split up, bi lobed shapes, non-gravitational forces and general complex unpredictable behaviour, one crazy idea (EU model) is not enough. We need a thousand crazy ideas and inputs!

  • Prof Harvey Rutt says:

    One can *start* with words; but without *numbers*, it rapidly becomes a sterile exercise.
    As I have repeatedly agreed, your proposed mechanism exists. It exists on the moon - at a minute level.
    But, contrary to your statement, there are quantitative estimates of the degassing rates, and they are orders of magnitude bigger than any conceivable proton influx mechanism. They do not pre suppose any particular source.
    Basically you are content to build tottering towers of words with no basis in science whatever. Fine, amuse yourself, I'm not.
    I don't 'believe' in the sublimation model. So far, I see evidence that is quantitatively reasonably consistent with such a model. I'm entirely open to any other model which quantitatively explains the facts; proton influx quite clearly is not.
    Enjoy the SciFi, just don't confuse it with science.

  • dave says:


    Do you relly have no opinion? about comet formation and its life cycle.

    Accepting there is not enough evidence for any rigid conclusion. You could always qualify it.

    Even Fred made a reasonable theory out of little data 60 years ago.

    But now we can see a bit more, perhaps his assumptions need modifying.

    The debate on the electrical experiment is dead, yes that method is a possibility, but also its not enough for the quantities see, al beit we dont have much data about that either.

    Surely you would have a view?

    As I have already said there is no science on this blog, we have no data.

  • Prof Harvey Rutt says:

    We have quite a lot of data, though it's preliminary. A mass, a density, an area, a rough out gassing rate, considerable information on gas temperature and composition, an albedo, a spin rate, surface temperatures, and more.
    Any theory has to be consistent with those, or show why they are wrong. We don't have confirmed detail yet, refereed papers, it's too early for that, but there are reasonable indications.
    Since there is no credible external source of the observed water and CO2, its source must be internal.
    Broadly these appear consistent with what one might call, I suppose, a dirty snowball covered in black gunk, to use a highly scientific term. There certainly is something odd about the reported temperature, which suggests something unexpected about the internal structure and possibly the spectral variation of albedo.
    But in the end it will need *numerical* model consistent with both physics and the data to decide if that's right.

    I totally fail to understand why many people here seem to think the data so far confound a model of that type. They appear entirely consistent with it to me, give or take the thermal issue, which needs sorting.
    What is absolutely clear is that no credible alternative model has been presented. Talk of 'electric forces' making the density wrong is risible.
    It will of course become much clearer as 67P approaches the sun.

    • Sovereign Slave says:

      A few thoughts. One, when you say, "We have quite a lot of data, though it's preliminary," I agree. The very partial and very incomplete data we have I believe is insufficient to draw any conclusions with, mathematically or otherwise. Two, accounting for every known variable and influence this complicated is mathematically impossible, and that's not accounting for the unknown variables and influences. Three, it's too easy to lie with numbers (no, I'm NOT saying that's what you're doing at all, just pointing it out). Economists do it all the time. And yes, math certainly has it's place and it's uses, Rosetta getting to P67 is a fine example, but it was used as a modeling process needing regular adjustments, recalibrations, etc. There are many other facets to the scientific method, math being at times one useful aspect. But ultimately, you can jimmy math to consciously or unconsciously say pretty much whatever you want. Otherwise, ALL mathematicians would be in complete agreement about everything, no?

      • Prof Harvey Rutt says:

        Sorry, but that's largely nonsense.
        You can mess with statistics for example, to produce missleading results for the general public. 'Lies damned lies and statistics' is an old saw. It generally does not work on those who actually know maths/statistics. You cannot 'Jimmy math' or whatever the phrase was. It has absolutely strict rules, and by and large an attempt to deceive is obvious.
        Math, quantitative data, is the absolute root of the physical sciences, and nowadays to a large extent the biological sciences too. Math is essentially the language of science, and in the physical sciences you cannot practise it without speaking it.
        There are indeed many things we don't know - I'm glad to say, or it would be far less fun, and I'd be out of a job. There is much about the comet we don't know. But there are other areas in which our understanding is in fact extensive, and from that understanding it is perfectly possible to make order of magnitude estimates with considerable confidence. Much of this discussion frequently calls on mysterious unknown processes in areas where our understanding is actually very good, and frequently simply ignores basic physics. A good case would be the interaction of energetic protons with a low density gas. That is *well, numerically*, understood, and has been for a long time. You don't, for obvious basic physics reasons, make water molecules like that. It also often cites process which do indeed exist - but are orders of magnitude too weak to explain what it's claimed they explain. Unless you can 'run the numbers' it's easy to end up with utter nonsense.

        • Sovereign Slave says:

          Thanks for the reply, prof, and again I must agree with you, much of what I say is largely utter nonsense, but for some reason that's not restrained me from continuing to say it. I've found the Rosetta blog discussions quite fun and entertaining, though the increasing redundancy of speculation minus solid facts has been a testament to man's fascination with debating the increasingly trivial. The debate between EU theory and standard model theory going on here I'd say was pretty much even until you came along and scared everyone off by applying mathematical formula all over the place. So bravo, your entry into the debate is quite refreshing.

          Now from what I can tell, everyone seems to agree that there are some type of electrical forces at play with P67 (obviously as there are instruments on board Rosetta to measure these things) and it's seems that there is agreement that electrical interactions among celestial bodies can generate degassing rates. Now, here's my question. If P67 had a much greater charge differential in relationship to the sun than lets say the moons charge differential to the sun, say by many many "orders of magnitude," is it possible that this could affect the amount of degassing of P67 compared to that of the moon? And have your mathematical calculations factored in the degree of electrical charge differential between P67 and the sun's heliosphere? And whether you believe this charge differential would make a difference or not, could you effectively integrate it into you mathmatical calculations just to see what the results are?

        • Sovereign Slave says:

          Second post attempt:

          Thanks for the reply, prof, and again I must agree with you, much of what I say is largely utter nonsense, but for some reason that's not restrained me from continuing to say it. I've found the Rosetta blog discussions quite fun and entertaining, though the increasing redundancy of speculation minus solid facts has been a testament to man's fascination with debating the increasingly trivial. The debate between EU theory and standard model theory going on here I'd say was pretty much even until you came along and scared everyone off by applying mathematical formula all over the place. So bravo, your entry into the debate is quite refreshing.

          Now from what I can tell, everyone seems to agree that there are some type of electrical forces at play with P67 (obviously as there are instruments on board Rosetta to measure these things) and it's seems that there is agreement that electrical interactions among celestial bodies can generate degassing rates. Now, here's my question. If P67 had a much greater charge differential in relationship to the sun than lets say the moons charge differential to the sun, say by many many "orders of magnitude," is it possible that this could affect the amount of degassing of P67 compared to that of the moon? And have your mathematical calculations factored in the degree of electrical charge differential between P67 and the sun's heliosphere? And if not, whether you believe this charge differential would make a difference or not, could you effectively integrate it into you mathmatical calculations just to see what the results are?

  • Prof Harvey Rutt says:

    Incidentally, right now, given the failure of the cold gas thruster let's hope the 'black gunk' is sticky!

  • dave says:

    Thanks Prof,

    Its good to know your position.

Comments are closed.