Rosetta reveals comet’s water-ice cycle

ESA’s Rosetta spacecraft has provided evidence for a daily water-ice cycle on and near the surface of comets. This story is mirrored from the main ESA web portal.

ESA VIRTIS info

Comets are celestial bodies comprising a mixture of dust and ices, which they periodically shed as they swing towards their closest point to the Sun along their highly eccentric orbits.

As sunlight heats the frozen nucleus of a comet, the ice in it – mainly water but also other ‘volatiles’ such as carbon monoxide and carbon dioxide – turns directly into a gas.

Comet 67P/Churyumov–Gerasimenko 12–14 September 2014 taken with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS on 12 (top), 13 (middle) and 14 September (bottom), in the optical band at 0.7 micron. The images focus on Hapi, a region on the comet's ‘neck’, one of the most active spots on the nucleus at the time. The first and second image were taken about 12 hours apart, and therefore are separated by about one comet rotation; the second and the third were taken about 37 hours apart, so the comet had undergone three rotations in the meantime. Owing to the complex topography of the comet, the illumination conditions are different in each of the three images, as shown by the shadows covering different patches on the surface. Using infrared spectra taken at the same time with VIRTIS, scientists identified water ice repeatedly appearing and disappearing, visible only on patches of the surface that were in shadow. This suggests that the water ice undergoes a daily cycle, forming during the local night from the sublimation of subsurface material and disappearing on the next comet day, just after local dawn. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015)

Comet 67P/Churyumov–Gerasimenko 12–14 September 2014 taken with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS on 12 (top), 13 (middle) and 14 September (bottom), in the optical band at 0.7 micron. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015). Click for full image details

This gas flows away from the comet, carrying dust particles along. Together, gas and dust build up the bright halo and tails that are characteristic of comets.

Rosetta arrived at Comet 67P/Churyumov–Gerasimenko in August 2014 and has been studying it up close for over a year. On 13 August 2015, the comet reached the closest point to the Sun along its 6.5-year orbit, and is now moving back towards the outer Solar System.

A key feature that Rosetta’s scientists are investigating is the way in which activity on the comet and the associated outgassing are driven, by monitoring the increasing activity on and around the comet since Rosetta’s arrival.

Scientists using Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, have identified a region on the comet’s surface where water ice appears and disappears in sync with its rotation period. Their findings are published today in the journal Nature.

“We found a mechanism that replenishes the surface of the comet with fresh ice at every rotation: this keeps the comet ‘alive’,” says Maria Cristina De Sanctis from INAF-IAPS in Rome, Italy, lead author of the study.

The team studied a set of data taken in September 2014, concentrating on a one square km region on the comet’s neck. At the time, the comet was about 500 million km from the Sun and the neck was one of the most active areas.

As the comet rotates, taking just over 12 hours to complete a full revolution, the various regions undergo different illumination.

“We saw the tell-tale signature of water ice in the spectra of the study region but only when certain portions were cast in shadow,” says Maria Cristina.

“Conversely, when the Sun was shining on these regions, the ice was gone. This indicates a cyclical behaviour of water ice during each comet rotation.”

Maps of water ice abundance (left) and surface temperature (right) focusing on the Hapi ‘neck’ region of Comet 67P/Churyumov–Gerasimenko. These maps are based on images and spectra collected with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS on 12 (top), 13 (middle) and 14 September (bottom) 2014.Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015). Click for full image details.

Maps of water ice abundance (left) and surface temperature (right) focusing on the Hapi ‘neck’ region of Comet 67P/Churyumov–Gerasimenko. These maps are based on images and spectra collected with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS on 12 (top), 13 (middle) and 14 September (bottom) 2014.Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015).
Click for full image details.

The data suggest that water ice on and a few centimetres below the surface ‘sublimates’ when illuminated by sunlight, turning it into gas that then flows away from the comet. Then, as the comet rotates and the same region falls into darkness, the surface rapidly cools again.

However, the underlying layers remain warm owing to the sunlight they received in the previous hours, and, as a result, subsurface water ice keeps sublimating and finding its way to the surface through the comet’s porous interior.

But as soon as this ‘underground’ water vapour reaches the cold surface, it freezes again, blanketing that patch of comet surface with a thin layer of fresh ice.

Eventually, as the Sun rises again over this part of the surface on the next comet day, the molecules in the newly formed ice layer are the first to sublimate and flow away from the comet, restarting the cycle.

“We suspected such a water ice cycle might be at play at comets, on the basis of theoretical models and previous observations of other comets but now, thanks to Rosetta’s extensive monitoring at 67P/Churyumov–Gerasimenko, we finally have observational proof,” says Fabrizio Capaccioni, VIRTIS principal investigator at INAF-IAPS in Rome, Italy.

From these data, it is possible to estimate the relative abundance of water ice with respect to other material. Down to a few cm deep over the region of the portion of the comet nucleus that was surveyed, water ice accounts for 10–15% of the material and appears to be well-mixed with the other constituents.

Spectra of Comet 67P/Churyumov–Gerasimenko taken at infrared wavelengths with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, in September 2014. The black spectrum corresponds to a patch of the comet surface that was well illuminated at the time of the measurement; the red spectrum corresponds to a less-illuminated patch; and the blue spectrum to a patch of the comet surface that was cast in shadow. The black spectrum shows a weak dip between wavelengths of 2.8 and 3.6 micron, which is produced by organic compounds on the surface absorbing the comet’s thermal radiation. The shape changes gradually from the black to the red and then the blue spectrum. In the blue spectrum, the dip is much stronger and shifted towards shorter wavelengths (2.7 to 3.6 micron), showing the characteristic shape of an absorption feature caused by water ice on the surface. The three spectra demonstrate that water ice is only found on patches of the comet that are cast in shadow, suggesting a cyclical behaviour of water ice during each comet rotation. Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015)

Spectra of Comet 67P/Churyumov–Gerasimenko taken at infrared wavelengths with Rosetta’s Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, in September 2014. The black spectrum corresponds to a patch of the comet surface that was well illuminated at the time of the measurement; the red spectrum corresponds to a less-illuminated patch; and the blue spectrum to a patch of the comet surface that was cast in shadow.
The black spectrum shows a weak dip between wavelengths of 2.8 and 3.6 micron, which is produced by organic compounds on the surface absorbing the comet’s thermal radiation.
The shape changes gradually from the black to the red and then the blue spectrum. In the blue spectrum, the dip is much stronger and shifted towards shorter wavelengths (2.7 to 3.6 micron), showing the characteristic shape of an absorption feature caused by water ice on the surface.
The three spectra demonstrate that water ice is only found on patches of the comet that are cast in shadow, suggesting a cyclical behaviour of water ice during each comet rotation.
Credit: ESA/Rosetta/VIRTIS/INAF-IAPS/OBS DE PARIS-LESIA/DLR; M.C. De Sanctis et al (2015)

The scientists also calculated how much water vapour was being emitted by the patch that they analysed with VIRTIS, and showed that this accounted for about 3% of the total amount of water vapour coming out from the whole comet at the same time, as measured by Rosetta’s MIRO microwave sensor.

“It is possible that many patches across the surface were undergoing the same diurnal cycle, thus providing additional contributions to the overall outgassing of the comet,” adds Dr Capaccioni.

The scientists are now busy analysing VIRTIS data collected in the following months, as the comet’s activity increased around the closest approach to the Sun.

“These initial results give us a glimpse of what is happening underneath the surface, in the comet’s interior,” concludes Matt Taylor, ESA Rosetta Project Scientist.

“Rosetta is capable of tracking changes on the comet over short as well as longer time scales, and we are looking forward to combining all of this information to understand the evolution of this and other comets.”

“The diurnal cycle of water ice on comet 67P/Churyumov-Gerasimenko,” by Maria Cristina De Sanctis et al. is published in the 24 September 2015 issue of Nature.

Comments

79 Comments

  • Guili says:

    I don’t understand how such a cycle is not seen in the visible spectrum by a change on the optical properties of the comet surface (color, reflectivity, etc).
    If a layer of water ice is deposited each comet day, we should SEE it.

    • ianw16 says:

      @Guili
      “If a layer of water ice is deposited each comet day, we should SEE it.”

      How, exactly? By definitiion, to be able to exist on the surface it must be in shadow. As soon as it isn’t in shadow it sublimes. So how are we meant to see into shadow? I’d say spectral analysis is a pretty good bet!

      • Guili says:

        We can see in the shadow thanks to the albedo of the sunlit part.
        It means that Philae’solar arrays are covered in ice every day and its electronics too. Could it be that we locally cross the corona pressure which would be very bad for the electronics ?

    • Dale says:

      However the ice is deposited each night and in the shadow regions. They are too dark to be imaged so you don’t see. Re read

      “We saw the tell-tale signature of water ice in the spectra of the study region but only when certain portions were cast in shadow,” says Maria Cristina.

      “Conversely, when the Sun was shining on these regions, the ice was gone. This indicates a cyclical behaviour of water ice during each comet rotation.”

      Dale

      • Harvey says:

        Also, remember it’s condensing gas coming up from the interior. That will tend to freeze out below the surface, in the pores of the material. So it doesn’t follow that much will become visible directly on the surface, though some might. Even at night, ices would sublime to an extent if right at the low pressure surface – internally the pressures can be slightly higher, vapour pressures change very rapidly with temperature. The ices very close to the surface will sublime off first as it moves into daylight.
        So the ‘visibility’ of ices from this process could be pretty low, and very transient.
        I would assume this apparently gentle, cyclic process is quite distinct from more violent events – though one can envisage it being involved in the formation of the cavities postulated for some of those.

  • LEO says:

    I miss arrows going down to get a cyclic process.

  • OzObserver says:

    WOW! Nice find Rosetta/VIRTIS team! 🙂

  • Harvey says:

    In vacuum systems, we sometimes use ‘cryopumps’, basically just a surface so cold it condenses the gases (usually except hydrogen and helium) so pumping them. Most are cooled to near 4K. But every once in a while you have to warm your cryopumps up to dump the load of condensed gases.

    So the surface of 67P is acting just like a cryopump. During the night, it cryopumps the interior of the comet and accumulates a load of condensed water and depending on temperature other things; in daylight in dumps that load to space, ready to do it again the next night.

    Cryopumps in the laboratory characteristically produce a regular ‘wheezing’ noise from the cooler; its been the acoustic backdrop to many hours of my life; I’ll never hear it again without thinking of 67P.

    • Ramcomet says:

      Very very cool, Harvey! Ya old Wheezer! (Said with great affection)

    • logan says:

      Very fine allegory, Harvey. Given the ‘powdery’ nature of that neck’s area, lots of surface to ‘pump’.

      That ‘wheezing’ noise should be stress ‘shattering’. Lots of stress at that material up there…

      • Harvey says:

        The noise comes from the ‘displacers’, roughly pistons, in the Giffors-Mcmahon (I think they are) cooling engines used to condense the gas.
        You get so used to it wheezing away in the background you don’t hear it any more.
        What really would stress me would be if that noise *stopped*!

    • logan says:

      You said it somewhere: Several hundred ºC to get rid of adsorbed water. Adsorption seems to work on different rules. The kind of rules present at formative environments.

  • Kamal says:

    In the poster-sized picture, the dates 12,13,14 September appear to be wrongly dated 2015.

    • emily says:

      indeed the data is for 2014 (the graphic has since been corrected).

  • Sovereign Slave says:

    Wow. Very interesting findings and conclusions that seem well considered and feasible. Sublimated water seeping through the porous surface in the daylight heat, only to freeze on the surface at night. This appears to be a very gentle sublimation process. The neck area at that time, as they say and we all remember, was very active…with dust jets… countless, fast moving dust jets that there’s been all kinds of speculation about as to the mechanisms causing them. I don’t remember there being any suggestions that the jets are created by a gentle sublimation process that takes place through a porous surface though. And indeed, sublimating water seeping through a porous surface doesn’t seem capable of blasting dust from the surface in organized jets, or really having too much affect on the dust at all. Hopefully the Nature article will address this. I guess I always wonder too if the conclusions being drawn are inescapably the only ones possible, or if there could be other ways of interpreting the data.

    • ianw16 says:

      @Sovereign Slave
      The gas will “seep” until it reaches the surface, or very close to it. Once there it encounters vacuum. At that stage it will sublime and escape, or freeze, depending on temperature. The speed at which it escapes will vary according to species. With H2O this is about 0.7 km/s. This is normal in vacuum. Surface dust will be entrained within the escaping gas. That is what we have been seeing.
      I’m not sure what other ways of interpreting the data need to be invented, as this has been observed before, is reproducible in a lab, and the temperature data preclude any “alternative” warming mechanisms.

      • THOMAS says:

        @ ianw16

        “The speed at which it escapes will vary according to species. With H2O this is about 0.7 km/s.”

        How does “seeping” gas suddenly get accelerated to 700m/s in collimated jets, given that the “seepage” described here is totally inconsistent with the type of huge hypothesized pressure build-ups in hypothetical subsurface cavities which have been suggested by some as the only possible standard theory mechanism to energize the jets? And could you please provide references/links to your claim that this is “reproducible in a lab”.

      • Sovereign Slave says:

        Could be I guess, Ian, though you’re playing sort of fast and loose with your terminology. If the gas already is a gas, it’s already sublimated, right? So saying the gas will sublimate once it’s near the surface is sort of redundant. But nitpicking aside, if it is as you say, this seems reasonable. Perhaps each jet then represents the surface boundaries of each area that’s being sublimated. But why is the dust almost always being propelled straight up? Seems all the sublimating gas would have to be accelerated straight up as well for this to happen (as opposed to omni-directionally), and has this been demonstrated to be the norm for sublimated gas behavior in a vacuum? What determines the direction that a gas will be accelerated in a vacuum, and why would all the gas accelerate in the exact same direction?

        Regarding interpreting, your use of the word “inventing” is interesting. However, if the interpretation of the thing observed is inaccurate the first time, observing the thing again does not mean your interpretation is confirmed, nor does reproducing it in the lab, such as observing heat, being able to reproduce heat using fire, and saying fire is definitely the cause just because you see heat, as opposed to heat from a chemical reaction, or friction, etc.

        • Kamal says:

          SS: I once called it a “sloshing” substance to escape from being pinned down on whether it is solid, liquid or gas. Now “seeping” is being used, but it is not clear if ices can be said to seep. In another post Logan uses “diffusing”. 67p is giving us a real lesson on how sublimation works in a natural environment like a comet, something we don’t have much experience of (at least in the tropics). So far we only had sublimation of volatiles as an explanation of more energetic processes, but from Imhotep it seems gravity can combine to create processes at an intermediate level of energy. Yet to see how creation of ions fits into these mechanisms.

    • THOMAS says:

      “…sublimating water seeping through a porous surface doesn’t seem capable of blasting dust from the surface in organized jets, or really having too much affect on the dust at all.”

      Indeed. It would be a bit like claiming that our understanding of how morning dew forms by condensation is sufficient to account for the workings of geysers…

    • Kamal says:

      SS: Nowhere is anything said about “gentle sublimation”, so could we have a definition, please? As far as I can see you mean to say that something is “gentle” if it cannot create a jet. In philosophy this is called mixing cause and effect. What prevents “gentle” as well as “non-gentle” sublimation? Why can’t there be a different mechanism to produce jets?

      Or perhaps you mean that “seeping” cannot create a jet. Nowhere is anything said about “seeping”. Could you define this, please? As far as I can see you mean to say that something “seeps” if it cannot create a jet. We are back to mixing cause and effect. What prevents “seeping” as well as “non-seeping”?

      I believe the difficulty is that you see two preconceived hypothesis, and you want to explain everything using one of them. When it doesn’t mix well with the facts, you use your imagination to interpolate various things into the facts to form a holistic picture in your mind. But the things you interpolated might give you a false picture. Wishing for a change of paradigm does not immediately resolve inconsistency.

      I must add that Earth-limited imagination (mine also) does not appear to get us far on 67P. It keeps doing several new things we have never seen to surprise us!

      • Sovereign Slave says:

        Hey, Kamal. Points taken, I may be playing fast and loose with my own terminology. But given that, I guess I would define gentle in this context with descriptive sublimation-specific words like “flows,” “porous,” and “finding it’s way to the surface,” (all words used in the article, as a matter of fact), as opposed to words like “explosive,” “pressure,” and “force,” (words not found in the article). So the word gentle seems appropriate to me and was not in any way suggesting that this was the paradigm expansion I meant. Seeping basically same as above, indicating a somewhat long process of gas “finding its way” to the surface, as opposed to blasting its way to the surface, which seems to be the general best guess presented on how the jets are formed..

        As far as hypothesis, I actually can’t conceive at all of how the jets form, and the point of my post was not to advance my own hypothesis, but to highlight that gentle (sorry) sublimation certainly can’t account for (and seems to even contradict) being a mechanism for the jets, especially when the authors repeatedly say that the gas “flows” away from the comet. So sure, there must be other mechanisms causing the jets, but that whole area appears to be dust, and therefore porous, and there were definitely a lot of jets emanating from it (and no doubt still are), so I’ll put the ball back in your court – how does the sublimation process described in this article create fast moving columnized dust jets?

    • logan says:

      Hi Sovereign Slave. Several processes going on the escaping ‘atmosphere’, many vertically structured, not all of them ‘jets’.

      On remembering that beautiful, long, ‘perfect’ non-‘jet’ seen at the neck shortly after arrival. Actually think of it more like a pleasant cigarette smoke line at a quite corner. Driving forces being not that of convection, but electrostatics.

      Of course, could be wrong 🙂

  • logan says:

    Think non-capillary ices like these nightly depositions are very erosive at the molecular level.

    • logan says:

      Hypothetical charges could be ‘trailed’ up along with this eroded super-fine material.

      67P’s core could be delivering charge units, in a discrete -non continuous flow.

      Another charge transfer mechanisms could apply.

    • logan says:

      Charges not being ‘pushed’ by tremendous Voltages. Charges being literally transported, along with the material, over the gentle force of the dust outflow 🙂 This fits well.

      • logan says:

        This is for surface inducted charges. UV two pass generated ions/electrons subject only to field forces, doesn’t have this initial gas ‘kicking’ 🙂 Think OriginalJohn suggested on the hundred[s] V.

  • originalJohn says:

    Optical and infrared VIRTIS data is interpreted as being indicative of a water ice cycle. Note that it is an interpretation and is based on surface and subsurface models, ie assumptions. It is not a conclusive result.
    The scale maximum on the map of “water ice abundance” is given as > 5%. This is shown white, indicative of saturation, so the greater than symbol is reasonable.
    On the ViRTIS temperature map however the scale maximum is labelled as an actual temperature, – 63 deg C, also shown white, ie the instrument is saturated at -63 deg C. The greater than symbol has been omitted obscuring the fact that white represents saturation and thus – 63 deg C or greater. The white temperature regions could therefore represent any temperature within a range – 63 deg C to close to infinity and have not been measured.

    Returning to the blue coloured regions interpreted as signifying water ice and which are in the vicinity of the temperature hot spots they could only be indicative of ice if the temperature was less than 0 deg C, and there is no evidence of that due to instrument saturation.

    The spectrum is thus water at an indeterminate temperature. Not evidence of ice. The interpretation relies on the assumption of ice.

    Water could be present at the surface as a reaction product and show the same spectrum.

    Another and more viable conclusion of the ViRTIS data would be that the saturation on the temperature map indicates unknown temperatures above – 63 deg C therefore may not be indicative of ice. Further sensitive temperature measurement is essential before the presence of ice can be confirmed.

    • sjastro says:

      If only you invested a bit of time on learning the science of the IR spectroscopy.

      Water molecules do some interesting things, the OH bond vibrates, stretches and bends at various frequencies in the IR range. These frequencies are unique to water and provide a chemical fingerprint.

      Furthermore the intensity of the major absorption peak in the water IR spectrum changes with temperature due to changes in hydrogen bonding.
      The IR spectrum of water is distinctly different in the solid, liquid and gaseous states.

      Hence your conclusion that scientists are in the dark over temperature and the presence of surface ice is an assumption is so completely and utterly wrong.

    • Booth says:

      originaljohn!

      Let’s try this again!

      http://blogs.esa.int/rosetta/2015/07/20/inside-imhotep-2/#comment-501931

      You write, “Optical and infrared VIRTIS data is interpreted as being indicative of a water ice cycle. Note that it is an interpretation and is based on surface and subsurface models, ie assumptions. It is not a conclusive result.”

      Wrong again! The VIRTIS data indicates the presence of water ice! It is NOT based on models or assumptions! It is based on the spectra of water ice! Allow me to quote from the last figure in the article – “The shape changes gradually from the black to the red and then the blue spectrum. In the blue spectrum, the dip is much stronger and shifted towards shorter wavelengths (2.7 to 3.6 micron), showing the characteristic shape of an absorption feature caused by water ice on the surface.”

      You write, “On the ViRTIS temperature map however the scale maximum is labelled as an actual temperature, -63 deg C, also shown white, ie the instrument is saturated at -63 deg C.”

      Once again, you are so very wrong! Please reread my earlier post and the seven journal articles referenced within (if you have trouble finding them, let me know, and I will post links to same! As you will recall, VIRTIS is able to measure temperatures in excess of 700 K. Thus, the VIRTIS temperature data is accurate. Your interpretation of actual scientific data is clouded by your world view. The white temperature region represents a temperature of 210 K (with appropriate error bands of course). The maps presented in this article are accurate. The highest temperature being measured, and shown, in the attached images is 210 K! There is no saturation! I feel I must repeat that … the temperatures measured by VIRTIS are NOT saturated! I must ask why find it so hard to accept this fact?

      You write, “The white temperature regions could therefore represent any temperature within a range -63 deg C to close to infinity and have not been measured.”

      Given the operational characteristics of real scientific instruments, I am curious about your claim that the temperature could somehow be “close to infinity.” That would certainly be something to see on a comet.

      You write, “Returning to the blue coloured regions interpreted as signifying water ice and which are in the vicinity of the temperature hot spots they could only be indicative of ice if the temperature was less than 0 deg C, and there is no evidence of that due to instrument saturation.”

      Wrong again regarding saturation! And wrong again about the temperatures of cometary ices. Just for the record, water ice experiences eight specific temperature transitions that lead to various forms of sublimation activity (Bar-Nun et al (1987) – please make note of the date)! What follows is a brief summary of countless experiments on amorphous solid water (ASW) and it’s transformed variations!

      Cometesimals are formed when gravitational accretion processes pull together volatile ices and dust. Van der Waal forces help to hold these “cold” or “low kinetic energy” volatiles in porous voids while the ASW matrix slowly forms around them. For H2 to be captured, the formation temperature of the comet needs to be below 20 K. For carbon monoxide, the comet temperature is below ~25 K, while NH3 can be captured at temperatures below ~28 K. Restated, ASW is very porous, with voids that are filled with other volatiles with lower sublimation temperatures. Lab experiments have shown that water ice experiences eight distinct, and irreversible, temperature dependent outgassing episodes. As temperatures increase, the water molecules repack, or rearrange, resulting in the outgassing of supervolatiles, like H2, CO, CO2, NH3, etc. In the process, some water ice is also entrained. Thus, at

      25 K – gases frozen to nucleus surface sublimate / evaporate
      35 K – irreversible annealing stage / supervolatile outgassing including some water
      44 K – adsorbed gases on the nucleus surface sublimate / evaporate
      80 K – irreversible annealing stage / supervolatile outgassing including water
      120 K – irreversible annealing stage / supervolatile outgassing including water
      137 K – annealed amorphous ice transforms into cubic ice / outgassing
      160 K – cubic ice transforms into hexagonal form / further outgassing
      180 K – sublimating ice releases gases trapped in clathrate-hydrate cages

      You write, “The spectrum is thus water at an indeterminate temperature. Not evidence of ice. The interpretation relies on the assumption of ice.”

      Wrong! The spectra, as noted, shows the characteristic shape of an absorption feature caused by water ice! VIRTIS temperature data does not exceed 210 K in this specific case!

      You write, “Water could be present at the surface as a reaction product and show the same spectrum.”

      No! It has been shown time and again, that there is insufficient oxygen due to proton sputtering to produce the quantities of water being measured by MIRO (and other instruments). A volume (recently reported) of 300 kg/s is off the charts for anything other than comets made of water ice! Furthermore, your reaction waste products would have to freeze immediately to the surface to generate the spectra presented in the article. How would you explain the sudden lose of temperature?

      You write, “Another and more viable conclusion of the VIRTIS data would be that the saturation on the temperature map indicates unknown temperatures above -63 deg C therefore may not be indicative of ice. Further sensitive temperature measurement is essential before the presence of ice can be confirmed.”

      It is obvious that the “sensitive temperature measurements” have already been made. You just have to accept them as fact!

      • originalJohn says:

        On the VIRTIS temperature map you have an orange coloured scale Booth. White is nowhere on an orange scale. It represents an absence of orange, therefore saturation. You do not know the temperature in the white zone. Or if you think you do confirm it by measuring the temperature by some other means which is not at the limit of the instrument’s sensitivity.

        On the surface reaction issue there are no published measurements, that I am aware of, of quantities of oxygen released from the nucleus surface. There are no published measurements either of proton flux density or proton energy close to the nucleus surface so you would have no way of knowing the oxygen yield. Your oxygen deficiency assertion is an assumption derived from laboratory data. And figures for oxygen in the coma would represent only unreacted oxygen.
        The nucleus surface is known to be covered with a layer of hydrocarbons, millions of tons and a copious source of hydrogen and if the underlying material is rock there are vast quantities of oxygen available.

        And the loss of temperature to allow a water reaction product to form ice, surface ice, would occur if the reaction stopped, or stopped and started at a different site. We know this occurs but it appears that we have no data on it. Perhaps that is the water ice cycle.
        I should add Booth that I would not argue that ice could not exist on the nucleus surface. There are many eventualities that could result in that. I would argue that ice on the surface is not indicative of ice beneath the surface and I would argue that there is and never has been any evidence that this or any other comet nucleus is ice.

        But there is no need to argue about these VIRTIS results. There are other ways of getting at the truth, if that is the objective. If the jets from the nucleus are water vapour sublimed from comet nucleus ice they should consist of neutral molecules, allowing for the expected maximum 1ppm photoionisation, and should be displaying a temperature close to or below O deg C even as vapour, reduced even further by expansion under pressure. If the jets contain any significant quantity of ionised material they are not sublimed ice, or if the jet temperature is anywhere above 0 deg C or, giving you a bit of leeway, say above 100 deg C, they are not sublimed ice. I suspect we are not looking for marginal differences here. I would guess ionisation of the jets could be 50 % or higher and jet temperature could be many hundreds of deg C, or many thousands of deg C in the bright reaction zones close to the surface that we have seen sporadically in recent weeks.

        We have no published data yet on these jet properties.

        • sjastro says:

          Your post is analogous to someone believing in the tooth fairy and putting the onus on everyone else to prove them wrong.

          The onus is on you to show the evidence supports the electric comet theory. Instead you consistently argue the lack of data such as the “source of oxygen” somehow provides an excuse for keeping the electric comet theory afloat simply because scientists have not considered it.

          Suppose scientists did consider the “source of oxygen”. Then there is glaring problem of the comet density of 0.4 g/cc.
          Would you care to explain how an oxygen bearing rock such as silicates can have such low densities?
          If you can’t explain the “source of oxygen” then it becomes equally pointless to demand measurements for “proton flux density” which incidentally is way too low as a solar wind source or “proton energy” measurements as a mechanism for water formation.

          Let’s suppose we ignore the lack of an “oxygen source”, and the” low proton flux” and assume that your water formation mechanism is correct.
          In this case water is external and not intrinsically associated with the comet.
          Would you care to explain to us how this mechanism is consistent with the water loss data which was steadily increasing as the comet approached perihelion?
          How does your mechanism explain the presence of water ice in the shadow areas of the comet or is in any way consistent with the water ice cycle?

          The fact is science can be hard enough as it is without having to waste time on an electric comet theory which can be easily dismissed.

          • logan says:

            Hi Sjastro.

            Quite often we public show impatience, lack of proper language or knowledge of the timings of science.

            Neither scientists are, or should be, following our wanderings and lost ways.

            But like to think that they would find lovely if communities are build around their work.

            If so, they need at times to slow, extend his flaps, and go down and back to show the way South to the rest of the flock.

            And yes, even at times, would be nice from them to show to the loosen ones among the flock, why West is not South.

            Even after that, birds that go West, or North. But scientists made their part.

            As general public the onus is not in this side. Not the capacity, competence and access.

        • Booth says:

          originaljohn!

          Please see end of thread. Apparently it’s really late in my part of the world.

      • THOMAS says:

        Booth writes: “there is insufficient oxygen due to proton sputtering to produce the quantities of water being measured by MIRO (and other instruments).”

        Originaljohn writes: “On the surface reaction issue there are no published measurements, that I am aware of, of quantities of oxygen released from the nucleus surface.”

        sjastro (below) speaks of “the lack of an oxygen source”.

        As an answer to these three comments, I found this interesting statement of what would seem to be discreetly announced breaking news in the “Far-ultraviolet spectroscopy from inside the coma of comet” submission on the ALICE data (http://meetingorganizer.copernicus.org/EPSC2015/EPSC2015-727.pdf) to the 2015 European Planetary Science Congress held in Nantes last week:

        “Another interesting case is when the brightness of O I λ 1356 is comparable to that of O I λ 1304 but C I λ 1657 is weak, which implies electron impact on O2 as an important source. THE ORIGIN OF THE SIGNIFICANT ABUNDANCE OF O2 NEAR THE NUCLEUS REMAINS UNCERTAIN.” (my capitals for emphasis).

        (For those who would wish to quibble with the meaning of the last sentence, please note that it is the ORIGIN of the abundant oxygen which is “uncertain”, not its presence near the surface, which is clearly indisputable and undisputed.)

        Now in my book, the “significant abundance of O2” detected “near the nucleus” means:

        1/ that there is enough spare oxygen left over for it to be detected in significant quantities once much of it has combined with hydrogen to form the H20 which proponents of the standard theory instead see as proof of sublimating subsurface ice.

        2/ that the very presence of any oxygen near the nucleus, (the origin of which is “uncertain”), is unexpected and inexplicable by the standard theory, since it can play no role in the “sublimating ice” scenario.

        This revelation has, on the other hand, always been an actual expectation and prediction of the electric comet model, given the abundance of oxygen which is locked up inside the rocky nuclei of comets.

        • sjastro says:

          All you are doing is cherry picking the report and completely misrepresenting it.
          .
          (1) The paper refers to relative abundances not absolute abundances.
          The strength of the oxygen emission in the FUV spectrum is based on the relative contributions of molecules that undergo photo-excitation such as H2O, CO, CO2 and O2.
          O2 is a significant contributor to the emission RELATIVE TO THE OTHERS.. This doesn’t lead to the conclusion there are copious amounts of O2 at or near the surface.
          This is like arguing that since silicates are abundant in cometary dust, it must be abundant in the comet. But in reality dust only contributes a small percentage of the cometary mass hence the amount of silicate relative to the cometary mass is very small.

          (2) The paper only reinforces the evidence is at complete loggerheads with electric comets.
          Water is undergoing dissociation through photo-ionization instead of being produced.

          (3) If water is in fact being produced near and on the surface, this completely flies in the face of the MIRO results.
          The comet nucleus would be gaining water, yet MIRO has been showing an accelerated rate of water loss from the nucleus as the comet was approaching perihelion.
          Needless to say this is consistent with sublimation.

          (4) A rocky core would require the density to be at least five times greater unless you want to come up with something exotic such as pumice in which case an electric comet would need to be volcanic in origin:)

        • originalJohn says:

          Good points, well made, THOMAS, about an interesting reference. Odd that the authors rely on a complex and low probability process of dissociation to explain the atomic forms detected and consider no other possible explanation. They require photoionisation of water molecules to release electrons which in turn bring about the dissociation. This fails to take into account the low probability of photoionisation in view of the very small amount of ultraviolet radiation in the solar spectrum with sufficient energy to achieve ionisation.

          They are perplexed by what source might explain the abundance of oxygen molecules near the comet nucleus surface and are happy to leave it at that, offering no possible explanation. To them oxygen from nowhere.

          All of this arises from the strange desire to maintain photon radiation from the Sun as the only possible source of energy influencing reactions at the comet.

          As soon as the proton flux is considered everything becomes clear and straightforward. As you observe, the presence of oxygen molecules near the nucleus surface is readily accounted for by the release of oxygen from the rock by the impact of energetic solar protons. Not only that though. Atomic hydrogen was detected. It is a common product of incomplete combustion of hydrocarbons. Carbon was also detected, an obvious breakdown product of hydrocarbons and also a common incomplete combustion product. Carbon dioxide is on the other hand a complete combustion product and water forms in both complete and incomplete reactions. This would explain simply the observed variation in the water / carbon dioxide ratio from one period to another.

          The solar proton energy and density can vary widely even from hour to hour and the autonomous variations in both proton energy and flux density may also fluctuate with local conditions. So the amount of oxygen released from the comet rock would be expected to vary. At times of high proton input a surplus of oxygen would be expected for the quantity of hydrocarbon at a particular reaction site. The reaction would be complete and the surplus oxygen would appear and accumulate in the coma. At other proton energies and current densities insufficient oxygen might be released to complete the reaction and products like atomic hydrogen, carbon monoxide, carbon and formaldehyde, all of them incomplete combustion products, would accumulate in the coma near the nucleus. All of these have been found.

          It should be noted that there would be differences in the flame for oxygen depleted and surplus oxygen combustion but complex differences. The depleted flame would still appear bright for example, perhaps even brighter. The appropriate instruments could however easily distinguish the two.

          • sjastro says:

            @originaljohn wrote,

            “Good points, well made, THOMAS, about an interesting reference. Odd that the authors rely on a complex and low probability process of dissociation to explain the atomic forms detected and consider no other possible explanation. They require photoionisation of water molecules to release electrons which in turn bring about the dissociation. This fails to take into account the low probability of photoionisation in view of the very small amount of ultraviolet radiation in the solar spectrum with sufficient energy to achieve ionisation.”

            Thank goodness the laws of physics don’t follow your recipe as life on Earth would have been well and truly sterilized out of existence by high energy UV photons. Fortunately these photons are filtered out by an ozone layer at a ridiculously low number density of around 1000 molecules /cc.

            Where you go terribly wrong is assuming that photon ionization through collisions are a low probability event.
            A single photon is defined by its mean free path length which is the distance travelled by a photon between successive collisions with atoms and molecules.

            https://en.wikipedia.org/wiki/Mean_free_path

            As you can see from the table even in rarefied conditions photons travel small distances between collisions. If the medium is thicker than the photon free path length, then virtually all the photons will experience collisions.

            It should also be noted that collisions involving photons can result in either ionization or scattering.

            The other point you get wrong is assuming the degree of photo-ionization is weak simply because of the small amount of UV in the solar spectrum.
            What this doesn’t take into account is that the FUV spectrum is the result of a UV photon emitted when an electron collides into a water molecule which results in disassociation. This UV photon in turn can initiate the release of other electrons resulting in cascade type reactions.

            You wrote.
            “They are perplexed by what source might explain the abundance of oxygen molecules near the comet nucleus surface and are happy to leave it at that, offering no possible explanation. To them oxygen from nowhere.”

            Like Thomas you either don’t understand the concept of relative abundance or you simply reading your own bias into the subject.

            As to where the O2 comes from, here is another report that might makes things clearer.

            http://www.esa.int/Our_Activities/Space_Science/Rosetta/Ultraviolet_study_reveals_surprises_in_comet_coma

            Since O atoms are produced in the disassociation process of water, it is likely the O2 molecules are probably formed from these O atoms given it is an energy preferred state.

            Notice this makes more sense than conjuring up magical rocks with densities of 0.4g/cc.

            Since you are unable to address this fundamental point the rest of your post which is bizarre in itself becomes irrelevant.

            I am still waiting on your responses to the various questions I have asked in previous posts.

          • sjastro says:

            @originaljohn also wrote.

            “As soon as the proton flux is considered everything becomes clear and straightforward. As you observe, the presence of oxygen molecules near the nucleus surface is readily accounted for by the release of oxygen from the rock by the impact of energetic solar protons.

            It certainly isn’t clear and straightforward.

            Given that oxygen is a divalent atom and can form double bonds, the H+ (proton) attaches itself to the oxygen as follows.

            =O + H+ —> -OH

            This what a chemist refers to as an electrophilic addition reaction where an electrophile such as a proton interacts with electrons in the O double bond to form a single hydroxyl bond (-OH).

            This mechanism is used to explain the existence of water on the moon.
            Given the moon is made of rock and has a density of 3.34 g/cc it has the requirements that you simply assume is the case for the comet despite the data.

            The formation of water on the moon is believed to be a multistep process.

            S=O + H+ —> S-OH
            (S=O can be part of the silicate or oxide chemical structure of the rock.)
            2 S-OH —> S=O + S + H2O
            or 2 S-OH —> S-O-S + H2O

            Notice there is ABSOLUTELY NO OXYGEN EMITTED in the process.
            The oxygen remains as a chemical constituent of the rock.

            Hence your mechanism doesn’t work even if the comet was made out of rock.
            It is far more energetically favourable for the protons to interact with the electrons in the oxygen double bond than for the kinetic energy of the protons freeing oxygen from the rock.

          • logan says:

            “…The formation of water on the moon…”

            Thanks for the data, Sjastro 🙂

          • sjastro says:

            Thanks Logan,

            Just to clarify a point which I may not have explained very well.

            In the reactions

            S=O + H+ —–> S-OH
            2 S-OH —> S=O + S + H2O
            or 2 S-OH —> S-O-S + H2O

            S is the rock surface and the O atoms are bonded directly to this surface and do not form the silicate or oxide chemical composition of the rock as I my have unwittingly implied in the original post.

  • logan says:

    Thanks a lot to De Sanctis et al. for this exemplary work on disciplined science. Also to all the Teams an to Emily.

    • originalJohn says:

      Lets start withe this sjastro ” the H+ (proton) attaches itself to the oxygen as follows…”. The proton of course is not capable of attaching itself to anything. It either becomes attached or does not depending on the conditions of the collision. As the proton energy is at least within the range 1-10 keV ( background ; could be much more within the coma) and the OH bond dissociation energy is 4.8 eV the OH bond cannot form. The protons are far too energetic.
      As for your hypothetical set of reactions for water formation on the Moon they completely ignore the energy of the protons. The Si-O bond energy is 4.68 eV. The proton impact transfers an energy, once again, of 1-10 keV which will cascade the separation of hundreds of Si-O bonds releasing hundreds of oxygen atoms per proton. Combination of these energy dissipated protons with oxygen atoms to form water as OH then H-OH is possible.
      The set of reactions you cite would require none of the Si-O bonds to be separated ie no energy input into the reaction. Rather unlikely in view of the proton energy. Of course there are those who would readily point out that this proton/ oxygen route for water on the moon would require the deuterium- helium ratio of the resulting water to match that of the Sun. I have not checked whether it does or not as we are not discussing the Moon here.

      The situation on the surface of the comet nucleus is different from the Moon in one significant respect. The comet is coated with a layer of hydrocarbons. The protons in this case cascade release the oxygen from the Si-O bonds in the rock and the free oxygen, with activation input also from the protons, then reacts exothermically with the hydrocarbon to form water in a combustion reaction, along with multiple other combustion products, including surplus oxygen, depending on whether the combustion reactions go to completion or not. Some proton oxygen reactions may also occur, who knows but I suspect the exothermic hydrocarbon combustion reaction is more favourable.
      Perhaps you would care to explain your assertion that it is far more energetically favourable for the protons to interact with electrons in the oxygen double bond.

      The point about the UV photoionisation is that the photons must carry enough energy to exceed the ionisation energy of water and only a very small proportion of the solar photons do, in a particular UV band. ESA have suggested in an old poster publication that this would be typically one millionth of available photons. The same ionisation energy requirement is there for any freed electrons, electrons which are incidentally discharging across the electric field at the nucleus surface, ie being removed from the reaction zone.

      • sjastro says:

        originajohn wrote,

        “Lets start withe this sjastro ” the H+ (proton) attaches itself to the oxygen as follows…”. The proton of course is not capable of attaching itself to anything. It either becomes attached or does not depending on the conditions of the collision. As the proton energy is at least within the range 1-10 keV ( background ; could be much more within the coma) and the OH bond dissociation energy is 4.8 eV the OH bond cannot form. The protons are far too energetic.”

        If only physics and chemistry was that simple.

        According to you the reaction goes through this rather simplistic pathway.

        REACTANTS ——-> PRODUCTS

        In reality it goes like this.

        REACTANTS ——-> TRANSISTION STATE —–> PRODUCTS.

        Part of the excess energy from the protons is used to form the TRANSITION STATE.
        The TRANSISTION STATE then loses any remaining excess energy primarily through heat to form the products.
        These are exothermic reactions.

        So in fact the OH bond is formed despite the energy of the protons.

        You wrote,

        “As for your hypothetical set of reactions for water formation on the Moon they completely ignore the energy of the protons. The Si-O bond energy is 4.68 eV. The proton impact transfers an energy, once again, of 1-10 keV which will cascade the separation of hundreds of Si-O bonds releasing hundreds of oxygen atoms per proton. Combination of these energy dissipated protons with oxygen atoms to form water as OH then H-OH is possible.
        The set of reactions you cite would require none of the Si-O bonds to be separated ie no energy input into the reaction. Rather unlikely in view of the proton energy. Of course there are those who would readily point out that this proton/ oxygen route for water on the moon would require the deuterium- helium ratio of the resulting water to match that of the Sun. I have not checked whether it does or not as we are not discussing the Moon here.”

        On the contrary, the Moon is an excellent example as it has the magical ingredients that are required for the your electric comet.

        We can put your mechanism to the test on the 430 odd kgs of moon rock collected (mainly through the Apollo missions, the rest through Moon rock that has found its way to Earth as meteorites.)

        Since in your mechanism O is depleted , it’s a simple case of measuring the O/Si ratio in silicate moon rocks via mass spectrometry and compare it against silicate Earth rocks where there is no depletion of O.

        Needless to say there is no difference between the two hence your mechanism is wrong.

        You wrote.
        “The situation on the surface of the comet nucleus is different from the Moon in one significant respect. The comet is coated with a layer of hydrocarbons. The protons in this case cascade release the oxygen from the Si-O bonds in the rock and the free oxygen, with activation input also from the protons, then reacts exothermically with the hydrocarbon to form water in a combustion reaction, along with multiple other combustion products, including surplus oxygen, depending on whether the combustion reactions go to completion or not. Some proton oxygen reactions may also occur, who knows but I suspect the exothermic hydrocarbon combustion reaction is more favourable.
        Perhaps you would care to explain your assertion that it is far more energetically favourable for the protons to interact with electrons in the oxygen double bond.”

        Well given your Si-O bond breaking mechanism is shown to be incorrect anyway and the comet is not composed of rock despite your denials, this is all a moot point.
        The reason however why the protons interacting with the electrons in oxygen double is energetically favourable is that the energy difference between the REACTANTS and TRANSITION STATE is less than the energy required in wiping out the Si-O bonds.
        This is related to a very simple point it is “easier” to form a chemical bond (in this case the O-H bond) then to break the Si-O bond.

        You wrote,

        “The point about the UV photoionisation is that the photons must carry enough energy to exceed the ionisation energy of water and only a very small proportion of the solar photons do, in a particular UV band. ESA have suggested in an old poster publication that this would be typically one millionth of available photons. The same ionisation energy requirement is there for any freed electrons, electrons which are incidentally discharging across the electric field at the nucleus surface, ie being removed from the reaction zone.”

        In this very thread I have already explained to you, that UV photons are also produced, when electrons dislodged by solar UV photons collide into water molecules. This is shown in the FUV spectrum. These UV photons in turn dislodge further electrons and create cascade reactions.

        So there is no need to conjure up magical discharging electric comets.

        • originalJohn says:

          Ah yes magic, sjastro, like the big bang, inflation, dark matter, dark energy, dark flow, neutron stars, the fusion core Sun, metallic hydrogen, nebular accretion and comet ice sublimation, which make up consensus cosmology and astrophysics and none of which can be supported by evidence.
          The big difference with the electrical magic is that it is real and observable and there to be measured. I can see how it would appear as magic to you though. Not in the curriculum eh.

          Two further points from your statements. Even as you describe it the quantity of uv photons of sufficient energy to photoionise water still depends on the tiny proportion of such photons in the solar radiation. Hence the typical photoionisation of one millionth of neutrals.

          And I am well aware of intermediate reactions, running into the hundreds in hydrocarbon combustion for example. I have cited them on this blog as sources of elements and compounds found in the comet coma. However, regardless of the energy requirements for particular reactions, if the energy carried by each solar proton exceeds the Si-O bond energy by a factor of a thousand or so then the Si- O bonds will be separated and the subsequent overall combustion reactions are strongly exothermic. It is worth remembering too that combustion of hydrocarbons is extremely complex and that it is impossible to predict in detail, even with your assertive confidence. With analysis the reactions can however be constructed retrospectively.

          Interesting that you should claim that the comet is not rock. I must have missed the presentation of that contrary evidence.

          • sjastro says:

            originaljohn wrote,

            “Ah yes magic, sjastro, like the big bang, inflation, dark matter, dark energy, dark flow, neutron stars, the fusion core Sun, metallic hydrogen, nebular accretion and comet ice sublimation, which make up consensus cosmology and astrophysics and none of which can be supported by evidence.
            The big difference with the electrical magic is that it is real and observable and there to be measured. I can see how it would appear as magic to you though. Not in the curriculum eh.”

            You must be running short of ideas by having to dredge up tired old clichés that abound on pseudo and anti science sites such as Thunderbolts, where mainstream science is devoid of evidence and the laughable suggestion that astrophysicists know nothing about “electricity”.

            This does not validate electric comets and is nothing more than the false dichotomy fallacy at work.

            One of the many unanswered questions is for you to demonstrate the evidence supplied by Rosetta and Philae which supports electric comets.
            Simply arguing that mainstream is “wrong” makes electric comets “right” doesn’t cut it.

            You wrote,
            “Two further points from your statements. Even as you describe it the quantity of uv photons of sufficient energy to photoionise water still depends on the tiny proportion of such photons in the solar radiation. Hence the typical photoionisation of one millionth of neutrals.”

            The second logical fallacy you employ is argument by repetition. Repeating the same line over and over isn’t going to make it right.
            It will still be incorrect the hundredth time over as it is first time.
            As such I won’t bother giving you the same response except to state, the presence of a cometary ionosphere which is the combination of solar photons, ejected electrons, secondary photons and low density gas at work completely destroys the idea that photo-ionization is a small effect.

            You wrote
            “And I am well aware of intermediate reactions, running into the hundreds in hydrocarbon combustion for example. I have cited them on this blog as sources of elements and compounds found in the comet coma. However, regardless of the energy requirements for particular reactions, if the energy carried by each solar proton exceeds the Si-O bond energy by a factor of a thousand or so then the Si- O bonds will be separated and the subsequent overall combustion reactions are strongly exothermic. It is worth remembering too that combustion of hydrocarbons is extremely complex and that it is impossible to predict in detail, even with your assertive confidence. With analysis the reactions can however be constructed retrospectively.”

            Once again the argument by repetition at work.

            You claim to know about intermediate reactions but clearly do not comprehend it.
            Increasing the energy of the protons will increase the rate of OH BOND FORMATION not the rate of BOND DISSOCIATION. This is simple chemical kinetics at work.
            Since you quote bond dissociation energies for O-H and Si-O, what do you think the corresponding bond formation energies are? They have the same magnitude but different signs. In other words where energy is required to break bonds, energy is released when the corresponding chemical bond is formed. Hence chemical bond formation does not require external energy and is therefore the “preferred” process.
            When thermodynamics is introduced into the picture, the entropy of the captured protons in forming bonds is less than the entropy of the protons in the solar wind. Since bond formation is exothermic, the heat released into the surroundings may in fact increase the entropy of the surrounding solar wind.
            In this case not only is O-H bond formation energetically favourable but could also be spontaneous if the overall entropy increases.

            The other point that completely messes up your Si-O bond breaking mechanism is that the ionic bond between the metal and silicate groups is weaker than the Si-O covalent bond.
            So even if you want to conveniently ignore the science of kinetics and thermodynamics, why should these energetic protons break the Si-O instead of the weaker ionic bond?

            You wrote,
            “Interesting that you should claim that the comet is not rock. I must have missed the presentation of that contrary evidence.”

            I find it intriguing how the evidence you ignore, becomes the evidence that doesn’t exist.
            This indicates either intellectual dishonesty or self delusion.

            You ignore the density of the comet which is too low for it to be a rock.
            You ignore the presence of an ionosphere, which indicates photo ionization cannot be a limited process.
            You ignore the O/Si ratios of silicate Moon and Earth rocks are the same as hence the Si-O breaking mechanism via the solar wind is wrong.

            The list is far from exhausted……

            On top of this your so called contrary evidence is nothing more than pareidolia in operation with regards to images or making up “evidence” such as the physical variation of G.

  • logan says:

    If_ well down here volatiles are transiting in one sync pulsed way [exhaling], at formative environment could well be two way [breathing].

    • logan says:

      Update: Robin has properly signaled that two way transit of gases is plausible on a cold [and warming] surface.

      http://blogs.esa.int/rosetta/2015/09/29/an-update-on-comet-67pc-gs-water-ice-cycle/#comment-549964

    • logan says:

      The original idea [on a formative environment context] for this process read from Alembe.

    • originalJohn says:

      Well sjastro this is my final contribution to this discussion as in the absence of relevant data it is one hypothesis versus another. I will have more to say when the data is available. Your argument is based on the false premise that only one reaction can occur at the expense of all others. Ridiculous as the hydrocarbon combustion reactions demonstrate with hundreds of reactions occurring, many simultaneously. Such a degree of complexity that it is impossible to predict which reactions do occur and which don’t. The same would apply to the surface reactions from impact of energetic protons. Whatever reaction you prefer the proton induced bond separation will occur anyway as relatively enormous energy is being dissipated in the rock on impact even at solar wind background levels. Because there is such a surplus of energy, which reactions are thermodynamically favourable is of no consequence. The real proton energy and density is likely to be much higher than background because of natural plasma effects. No data available there. In any event if any energy reduced protons combined with electrons ( after dissipating their energy into Si-O bond separation) to produce atomic hydrogen and then with available oxygen to form OH, the OH bond would immediately be dissociated by subsequent proton impact. No OH would survive to react further. So no OH from the solar wind source then. And the fact that other reactions requiring no energy input can occur does nothing to prevent the proton energy separating Si-O bonds. So that reaction most definitely will occur. Your argument is wrong.

      As far as your Moon rock point is concerned you say if oxygen was released by proton Impact the rock would be oxygen depleted. Wrong again . The proton impact separates the Si-O bond releasing both oxygen and silicon so no oxygen depletion and no change in Si/ O ratio remaining in the rock. No surprise in the mass spec results then.

      With regard to photoionisation and the dependence on it of your hypothesis for all ions present in the coma, you argue that uv photons can be generated by other collisions and this would account for the necessary ionisation. But the collisions you cite are with solar uv photons which are severely limited. Typically one millionth of all neutral material can be photoionised. So the overall availability of sufficiently energetic uv photons is still dependent on the meagre availability in the solar wind.
      You completely ignore of course the obvious source of ions in the coma which is plasma discharge from the surface of the comet nucleus. One way of confirming or refuting this would be an ion analysis of the jets emitted from the nucleus. Incredibly the opportunity of gathering this fundamentally important data seems to have been rejected up to now. You prefer to stick to and base all your explanation on the tired old sublimation hypothesis, which requires photoionisation as the sole ion source.

      “Well given your Si-O bond breaking mechanism is shown to be incorrect anyway and the comet is not composed of rock”

      So given that your argument for lack of viability of the Si-O bond breaking mechanism is shown to be wrong the mechanism stands as a fully viable process. And your confidence that the comet is not composed of rock is rather premature since to my knowledge nobody as yet knows what it is made of. No data available, except the visual evidence that it has the appearance and topology of rock. Once again the opportunity appears to have been bypassed so far of qualitatively analysing the particles ejected from the nucleus, as the NASA Stardust mission went to great trouble to do with Wild 2. Such an analysis would provide some good clues as to what 67P is made of.

      “tired old clichés that abound on pseudo and anti science”
      The points raised appear to be tired and old sjastro because there is never any reply to them offered by the consensus. Never any justification for the faith in a whole bunch of evidence free imagination that forms the basis for current cosmology. And you call the electrical alternative pseudo science because it does not follow the consensus rules. It is quite definitely not anti-science. It is totally science based but definitely anti consensus based science. Anti pseudo science in fact.

      “the laughable suggestion that astrophysicists know nothing about “electricity”.

      Not so laughable at all. Judgement based on a complete lack of any electrical argument to explain any cosmological phenomenon. Results which demonstrate electrical behaviour come from NASA, and go. Such results are never referred to in subsequent explanations. Instead the tired old gravity only isolationist story continues despite the evidence. So there is very strong indication that the importance of cosmic electric currents is indeed being overlooked by astrophysicists. Actually it would be laughable if it was not so serious.

      “Increasing the energy of the protons will increase the rate of OH BOND FORMATION”

      False logic here sjastro. You make this statement despite recognising that the bonds you refer to require NO ENERGY INPUT. So increasing energy cannot increase bond formation. And as I have explained above the large surplus of proton energy will dissociate any bonds that happen to form.

      “One of the many unanswered questions is for you to demonstrate the evidence supplied by Rosetta and Philae which supports electric comets.”

      I have no control over that evidence sjastro. If it is not released it cannot be demonstrated. After more than a year in contact with the comet there is precious little evidence relating to electrical or plasma properties. Virtually none in fact. No measurement of charge state. No measurement of ion abundance in the jets or in the coma as a whole. No measurement of ion currents. No voltage measurements. And this applies when jets have erupted recently , just after perihelion, which had obvious plasma characteristics such as intrinsic illumination, orders of magnitude brighter than anything seen until then. Until that evidence is available one way or the other the electric comet concept remains a hypothesis, as does the ice sublimation hypothesis itself, also for lack of evidence.

      “The other point that completely messes up your Si-O bond breaking mechanism”

      Rubbish here sjastro. You state that the fact that the ionic bond is weaker than the Si-O covalent bond would mean that it would be preferentially separated. This would only apply if the energy available was close to the dissociation energy. In fact the large surplus of energy available in the proton flux means that such a constraint does not apply. All bonds that differed by a factor of hundreds from the proton energy would be separated easily.

      “I find it intriguing how the evidence you ignore, becomes the evidence that doesn’t exist.”

      Let us examine this accusation.

      I do not ignore the density of the comet nucleus. I fully accept that it is correct. I do not accept the explanation for it. I hypothesise that there is other explanation which is beyond your imagination.

      I do not ignore the presence of an ionosphere. I acknowledge it as a fundamental characteristic of a comet. I question the origin of it solely in photoionisation and explain why there would be insufficient particular photons available to account for the whole coma, by far. I propose plasma discharge from the nucleus as a much more likely and prolific ion source.

      And finally, I do not ignore the similarity in O/Si ratios of Earth and Moon rocks. I explain to you that both silicon and oxygen are separated and removed by proton impact therefore no oxygen depletion expected in the remaining rock.

      Your arguments convince yourself sjastro but nobody else. But for now no further argument on these issues.. The data is awaited. Why don’t you take the time to learn something useful about electricity and plasma.

      • sjastro says:

        You wrote,
        ” Your argument is based on the false premise that only one reaction can occur at the expense of all others. Ridiculous as the hydrocarbon combustion reactions demonstrate with hundreds of reactions occurring, many simultaneously. Such a degree of complexity that it is impossible to predict which reactions do occur and which don’t. The same would apply to the surface reactions from impact of energetic protons. Whatever reaction you prefer the proton induced bond separation will occur anyway as relatively enormous energy is being dissipated in the rock on impact even at solar wind background levels. Because there is such a surplus of energy, which reactions are thermodynamically favourable is of no consequence. The real proton energy and density is likely to be much higher than background because of natural plasma effects. No data available there. In any event if any energy reduced protons combined with electrons ( after dissipating their energy into Si-O bond separation) to produce atomic hydrogen and then with available oxygen to form OH, the OH bond would immediately be dissociated by subsequent proton impact. No OH would survive to react further. So no OH from the solar wind source then. And the fact that other reactions requiring no energy input can occur does nothing to prevent the proton energy separating Si-O bonds. So that reaction most definitely will occur. Your argument is wrong.”

        Since you don’t comprehend thermodynamics and kinetics and how these lead to preferred states and reactions, let me give you a simple example.
        Suppose there is a ball on the side of a hill. The ball is in a state of unstable equilibrium. The preferred final state is for the ball to roll downhill not uphill. If the ball is struck by a rock projected up the hill (equivalent to your colliding proton), it will still prefer to roll downhill irrespective of the kinetic energy the colliding rock.
        It may very briefly move uphill as a result of the collision (the excited transition state) before rolling downhill due to gravity and releasing kinetic energy.
        For the ball to move uphill potential energy increases which is clearly not a preferred state as WORK is required to move the ball uphill.
        Similarly the capture of protons in bond formation is the preferred state over bond disassociation. Bond formation releases energy, whereas bond disassociation requires increasing the potential energy to break the existing bond. Note that bond disassociation is an ENDOTHERMIC not an EXOTHERMIC reaction as you have erroneously claimed.
        The excess proton energy is taken up by increasing the rate of bond formation and is dependent on the Gibbs free energy of activation which is the difference between the initial and transition free energy states. The Gibbs free energy of activation is the thermodynamic version of WORK.

        Where the focus has been on the chemical effects of the solar wind on the lunar surface, the physical effects are far more prominent. The vast percentage of colliding protons and electrons do not engage in chemical reactions but are embedded in the lunar surface in what is known as solar wind implantation. This is accompanied by spallation or ejection of material from the surface. Higher energy solar wind particles penetrate deeper into the surface.
        Cosmic rays which are up to a million times more energetic than the solar wind penetrate deeper.

        You wrote,
        “As far as your Moon rock point is concerned you say if oxygen was released by proton Impact the rock would be oxygen depleted. Wrong again . The proton impact separates the Si-O bond releasing both oxygen and silicon so no oxygen depletion and no change in Si/ O ratio remaining in the rock. No surprise in the mass spec results then.”

        Not only does this fail Chemistry 101 but simple arithmetic. One of the basic building blocks of silicates is the [SiO4]]4- group.
        There are four oxygen atoms bonded to every Si atom. So you are not knocking out O and Si atoms on a one to one basis. Four O atoms are removed per Si atom.
        By some miraculous coincidence the depletion ratio Si/O is exactly tied to the chemical empirical formula of the silicate being tested!! Absolutely amazing!!
        We can take this nonsense even further by claiming that since the moon has been bombarded by the solar wind for around 4.5 billion years, there should be no Si or O at all in which case one would expect silicates to be completely stripped from the surface of lunar rocks.

        Once again the evidence shows your mechanism is wrong.

        You wrote,
        “With regard to photoionisation and the dependence on it of your hypothesis for all ions present in the coma, you argue that uv photons can be generated by other collisions and this would account for the necessary ionisation. But the collisions you cite are with solar uv photons which are severely limited. Typically one millionth of all neutral material can be photoionised. So the overall availability of sufficiently energetic uv photons is still dependent on the meagre availability in the solar wind.
        You completely ignore of course the obvious source of ions in the coma which is plasma discharge from the surface of the comet nucleus. One way of confirming or refuting this would be an ion analysis of the jets emitted from the nucleus. Incredibly the opportunity of gathering this fundamentally important data seems to have been rejected up to now. You prefer to stick to and base all your explanation on the tired old sublimation hypothesis, which requires photoionisation as the sole ion source.”

        Yet again the argument by repetition.
        What completely refutes your argument is the lack of a magnetic field around the nucleus. As we are constantly reminded moving charges generate magnetic fields. There are no ions being discharged from the nucleus as there is no magnetic field. Yet despite this point being mentioned on numerous occasions by various individuals you continue to ignore it and regurgitate the same nonsense.

        You wrote,
        “And your confidence that the comet is not composed of rock is rather premature since to my knowledge nobody as yet knows what it is made of………”

        Why don’t you provide the evidence that a SOLID rock can have a density as low 0.4g/cc. Otherwise speculating that comets are made from solid rock is pointless .

        You wrote,
        “”Increasing the energy of the protons will increase the rate of OH BOND FORMATION””
        False logic here sjastro. You make this statement despite recognising that the bonds you refer to require NO ENERGY INPUT. So increasing energy cannot increase bond formation. And as I have explained above the large surplus of proton energy will dissociate any bonds that happen to form.”

        The bond formation itself doesn’t require energy but you still need the energy to bring to bring the reactants together in order for the bond to form. That should be obvious in collision type theories on which this is based on.

        Perhaps I should have put the word RATE in capital letters. I suspect that even you would understand that reaction rates are temperature dependant. Higher proton energies have higher thermal energies which increase the OH bond formation reaction RATE.

        If as you claim “proton energy disassociates any bonds that happen to form”, then how are O2 molecules formed in your hypothesis not disassociated into O atoms and radicals by the very same high energy protons in the solar wind?
        You have effectively contradicted yourself and have shown the mechanism is not even self consistent.

        You wrote
        “I have no control over that evidence sjastro. If it is not released it cannot be demonstrated. After more than a year in contact with the comet there is precious little evidence relating to electrical or plasma properties. Virtually none in fact. No measurement of charge state. No measurement of ion abundance in the jets or in the coma as a whole. No measurement of ion currents. No voltage measurements. And this applies when jets have erupted recently , just after perihelion, which had obvious plasma characteristics such as intrinsic illumination, orders of magnitude brighter than anything seen until then. Until that evidence is available one way or the other the electric comet concept remains a hypothesis, as does the ice sublimation hypothesis itself, also for lack of evidence.”

        The theory that tooth fairies exist should not be dispelled until the evidence is provided one way or the other. As ridiculous as this sounds, this is how you are arguing the point.
        You are blissfully unaware that the data already supplied by the mission, such as the lack of a local magnetic field, the spectroscopic data, density, etc not only supports the mainstream view but effectively kills off electric comets. You are going to be waiting for a very long time for non existent data……..

        You wrote,
        “I do not ignore the density of the comet nucleus. I fully accept that it is correct. I do not accept the explanation for it. I hypothesise that there is other explanation which is beyond your imagination.”

        You are one confused individual that seems to forget what you have written in previous posts.
        For someone who accepts the density value, then what was the point of going through the exercise of trying to show that G varies? You accept the value but not the explanation? That makes absolutely no sense.

        You wrote,
        “I do not ignore the presence of an ionosphere. I acknowledge it as a fundamental characteristic of a comet. I question the origin of it solely in photoionisation and explain why there would be insufficient particular photons available to account for the whole coma, by far. I propose plasma discharge from the nucleus as a much more likely and prolific ion source.”

        For someone who claims to understand plasma physics better than anyone else, you are displaying considerable ignorance. Remember I explained the concept of free mean path length. Along with this concept is the associated time scale which is a very important concept in plasma physics. Photo-ionization does occur in the coma but so does the recombination of the electrons and positive ions back into neutrals. The time scale in the recombined or neutral state is longer than the ionized state hence the coma is predominately composed of neutrals. As the neutrals expand into the surrounding space, the density drops, ionization time scale increases and the recombination time scale decreases.
        The ionosphere is where ionization is the dominant process.
        How does this compare to your plasma discharge process? Well we already know it doesn’t occur, because of a lack of the magnetic field around the nucleus.
        Even if we ignored this inconvenient truth how does your plasma discharge start as predominately neutral in the coma and ends up mainly plasma in the ionosphere.

        It is simply yet another example of absurdness of your hypothesis which is contradicted by observation and experiment.

        You wrote,
        “Your arguments convince yourself sjastro but nobody else. But for now no further argument on these issues.. The data is awaited. Why don’t you take the time to learn something useful about electricity and plasma.”

        I’m sorry to disappoint you but I do know enough about plasma physics and electricity to realize how bereft of knowledge you are in these subjects.

        • originalJohn says:

          Sjastro, might I suggest that you stick to a factual argument and do not try to constantly belittle your adversary even though it makes you feel better. If your argument is good enough it should stand without personal content.

          And your argument is not good enough. You offer what to you are indisputable points on a QED basis but unfortunately for you all your points are highly disputable. For example on the WORK point. Whatever is more thermodynamically favourable, if sufficient energy is available the thermodynamics is of no consequence. So with your ball on a hill analogy let’s say it is a golf ball and a proficient golfer approaches it with an 8 iron, addresses it swings and strikes in the direction of the hill top. Of course it sends it up and over the hill regardless of the fact that the energetically more favourable possibility would be for it to roll down the hill after being tipped with a foot. So no debunk there sjastro. No proof that a solar proton striking rock could not separate the Si-O bond because of thermodynamic considerations. And the protons in the case in point are still available for capture in bond formation. Whether that bond ( the OH bond) would survive subsequent solar proton impact is debatable and would depend on local conditions. For example if the OH remained hugging the surface it would be highly susceptible to dissociation from subsequent dissipated energy of proton impact. Oxygen molecules however, released from the rock, would instantaneously be taken up in combustion reactions forming gaseous products that would be transported away from the surface with a very much lower probability of collision with protons. And if there was a surplus of oxygen it would evolve unreacted. And recent ESA results have shown that there is a strong incidence of molecular oxygen near the nucleus. So another indisputable point bites the dust, your contradiction point.

          Now back to the moon, the poor analogy moon, which resembles a comet only by being a rocky solar system body. You are fixated on the Si/ O ratio in the moon rock aren’t you sjastro. Indeed the structure is locally tetrahedrally coordinated but the structure over any unit cell is a ratio of 2 : 1 oxygen : silicon, hence the chemical formula SiO2 for silicate. So on average two oxygen bonds are separated for every silicon atom released, not 4. But anyway it makes no difference. If the oxygen and silicon are released in the same ratio as they exist in the structure there is no preferential depletion in the remaining rock. Get it sjastro? Another irrefutable point of yours refuted.

          Now the magnetic field sjastro. Why do you think this comet has no magnetic field? It was confirmed some time back in a published ESA paper discussed in Claudia’s blog post ” what made the comet sing” that the nucleus has a magnetic field. Take it up with the author Dr Glassmeier. So any assertions you make which depend on no magnetic field are nullified. Another one bites the dust sjastro. Of course the simplest way to determine whether the nucleus is discharging ions or not would be to measure the ion content of the jets. It will be done eventually. Too embarrassing to overlook.

          Right no time to waste on this one, your tooth fairy analogy. The electric comet theory and the combustion hypothesis are highly plausible and worthy of serious investigation as I am showing by cancelling out your “irrefutable” points. In fact tooth fairy springs to my mind when I see the ice sublimation hypothesis so confidently believed in.

          Now on the density issue sjastro you and I are not going to agree. However there is absolutely no confusion or inconsistency in my argument. Obviously the mass is correct for the assumed constant G value. The variables plugged into the force equation were the mass of the Rosetta craft, the separation between its centre and that of the nucleus and the measured force between them, with the mass of the nucleus unknown. With a different G value the mass would be different for the nucleus but the force exerted would be exactly the same. And it is that force that is used in the navigation calculations. ( the new G and the mass difference would cancel out in the equation) So perhaps a particular quantity of matter exerts a different force under some sub atomic structural conditions and therefore manifests as a lower measured mass, hence the anomalously low density. Get it sjastro or is it too much for you? It is an interesting one and others have applied themselves to it well before me. Look them up.

          And finally, plasma. I have never claimed to know more than everyone else about plasma. I do however judge other peoples knowledge including yours from what they say, what they believe is possible and the significance they attach to certain phenomena. I have had little discussion with you on plasma but your failure to acknowledge the significance of plasma behaviour or to recognise it in the Rosetta data, and your insistence on the dominance of photoinisation in the coma give you a low rating on plasma knowledge in my view. As I have pointed out repeatedly it is only possible for photoionisation to account for about one millionth of the ions in the coma ( ESA figure). Another prolific source is therefore necessary. In my view the coma is formed as a mixture of ions and neutrals by discharge from the comet nucleus. The ions remain as ions as they accumulate in the coma. I can see features of a plasma discharge in the discharge jets and in their variability ( a mixture of ions and neutrals is a plasma). Water and CO2 would discharge as neutral molecules some of which would be ionised, more likely by the proton flux than by photons. The actual proportions as far as I am aware are unknown, or at least unpublished. The results from the 1000 km flyaway should be enlightening there. It is however a complex state within the coma and spot or even line analysis could be highly misleading. A complete ions/ neutrals map is required with as high a resolution as possible and measured not modelled.
          With regard to mean free path length it is only significant if particles can interact with all other particles as in a gas. A plasma is not a gas and different considerations apply. Beyond the Debye radius any charged particle in a palsma is screened from any other charged particle and beyond that distance cannot interact. Charges therefore remain separated and there is no actual neutralisation. For this reason plasmas are often described as quasineutral, equal numbers of positive and negative ions but no interaction, hence the charge separation and electrical conductivity. Particle interaction can occur within the Debye radius but charge separation remains throughout the plasma as a whole.

          This has debunked your claimed debunk sjastro by succinctly highlighting the flaws in the major aspects of your argument.

          • sjastro says:

            Originaljohn,

            You have convinced me that thermodynamics is beyond your capability for comprehension and any further discussion in this area is pointless.
            Continue denying the evidence which supports the thermodynamic view and as well as propagating your own self delusionary views that some important discoveries are around the corner ready to smash the mainstream and propel science into the glorious world of electric comets.

            You wrote,
            “Indeed the structure is locally tetrahedrally coordinated but the structure over any unit cell is a ratio of 2 : 1 oxygen : silicon, hence the chemical formula SiO2 for silicate. So on average two oxygen bonds are separated for every silicon atom released, not 4. But anyway it makes no difference. If the oxygen and silicon are released in the same ratio as they exist in the structure there is no preferential depletion in the remaining rock. Get it sjastro? Another irrefutable point of yours refuted.”

            Silicates have the tetrahedral structure [SiO4]4- .
            https://en.wikipedia.org/wiki/Silicate

            In case you didn’t know tetra as in tetrahedron means four. You cannot form a tetrahedral shape with two O atoms!!!

            And while we are at it please explain why there is no Si and O depletion in this laboratory test of H+ and He+ irradiation of silicates.
            http://www.pnas.org/content/111/5/1732.full.pdf

            How much more evidence do you want that Si-O bond disassociation doesn’t occur?

            You wrote,
            ” Now the magnetic field sjastro. Why do you think this comet has no magnetic field? It was confirmed some time back in a published ESA paper discussed in Claudia’s blog post ” what made the comet sing” that the nucleus has a magnetic field. Take it up with the author Dr Glassmeier. So any assertions you make which depend on no magnetic field are nullified. Another one bites the dust sjastro.”

            Why don’t you try reading the article instead of cherry picking it. Your selective blindness has resulted in missing the obvious point that Rosetta did not land on the comet nor was anywhere near the nucleus or coma when the measurements where made.
            Philae on the other hand did land on the surface and found no magnetic field.
            So much for a magnetic field at the nucleus.

            Try reading this report instead and leave out the cherry picking.

            http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_and_Philae_find_comet_not_magnetised

            You wrote,
            “Now on the density issue sjastro you and I are not going to agree. However there is absolutely no confusion or inconsistency in my argument. Obviously the mass is correct for the assumed constant G value. The variables plugged into the force equation were the mass of the Rosetta craft, the separation between its centre and that of the nucleus and the measured force between them, with the mass of the nucleus unknown. With a different G value the mass would be different for the nucleus but the force exerted would be exactly the same. And it is that force that is used in the navigation calculations. ( the new G and the mass difference would cancel out in the equation) So perhaps a particular quantity of matter exerts a different force under some sub atomic structural conditions and therefore manifests as a lower measured mass, hence the anomalously low density. Get it sjastro or is it too much for you? It is an interesting one and others have applied themselves to it well before me. Look them up.”

            What “I do get” originaljohn, is this is a hopelessly inane argument.
            As usual you have missed the obvious point, the mass of the comet is not an unknown quantity but calculated from its orbit around the Sun.

            So which is the correct mass for the comet originaljohn?
            Is it the one where you change the value of G for Rosetta’s orbit around the comet to obtain a tailor made value, or calculated from 67P-C/G’s orbit around the Sun using measured orbital elements?

            Leaving the value of G as its EXPERIMENTALLY MEASURED VALUE, the calculated mass using either scenario will agree within experimental error.

            Which is the more logical process, mix and match the value of G to get any mass and density value you want, or to leave G as a constant and find the calculations automatically fall into place.

            The former involves pure nonsense the latter Science.

            You wrote,
            “And finally, plasma. I have never claimed to know more than everyone else about plasma. I do however judge other peoples knowledge including yours from what they say, what they believe is possible and the significance they attach to certain phenomena.”

            This is an apt summary of the generally illogical nature of your posts.
            Admitting you may not know more than anyone else but in the very next sentence pontificating about judging others is downright hypocritical.

            The point being you know far less about the knowledge base of the people you are criticizing than your own limited knowledge about plasma.

            You wrote,
            “With regard to mean free path length it is only significant if particles can interact with all other particles as in a gas. A plasma is not a gas and different considerations apply. Beyond the Debye radius any charged particle in a palsma is screened from any other charged particle and beyond that distance cannot interact. Charges therefore remain separated and there is no actual neutralisation. For this reason plasmas are often described as quasineutral, equal numbers of positive and negative ions but no interaction, hence the charge separation and electrical conductivity. Particle interaction can occur within the Debye radius but charge separation remains throughout the plasma as a whole.”

            Whereas this might sound impressive to the scientifically illiterate to everyone else it is mindless word salad. To suggest that distances beyond the Debye radius prevents interaction or recombination in plasma is so utterly ridiculous.

            For a start in plasmas of any density, the mean free path length between collisions resulting in recombination is many orders of magnitude greater the Debye length. So apart from completely contradicting your claim it indicates the Debye length does not hinder recombination. Energetic free electrons are still mobile irrespective of whether they are inside or outside the Debye sphere and can be captured by ions in the recombination process.

            Gas and Plasma in an ionizing environment exist in equilibrium. Whether one is favoured over the other depends on the density of the gas.

  • logan says:

    “137 K – annealed amorphous ice transforms into cubic ice / outgassing”

    This could explain at what temp Ducky has passed most of its forming life 🙂

    Thanks for approaching this data Booth!

  • Booth says:

    originaljohn!

    You write, “On the VIRTIS temperature map you have an orange coloured scale Booth. White is nowhere on an orange scale. It represents an absence of orange, therefore saturation.”

    Really?

    You, Sir, are incorrect once again! Based on your comments, I must conclude that you have no background in science or data presentation/visualization. When I was an undergrad (in physics and applied math), I was required to take a course in data visualization. Colour, as it turns out, operates at a psychological level. In this case, black is cold, orange is warm to hot, and white is hottest! The “orange” scale employed by the VIRTIS team is one of many colour scales that can be selected by the authors to convey an immediate perception of what is being presented – in this case temperature. The white portion of the scale does not represent saturation! It represents a temperature band of 200 to 210 K. Nothing more! Your claim of saturation is, once again, false!

    You write, “You do not know the temperature in the white zone. Or if you think you do confirm it by measuring the temperature by some other means which is not at the limit of the instrument’s sensitivity.”

    Actually we do know what the temperature is in the white zone. According to the scale, any pixels displayed as “white” are between 200 and 210 K. Capaccioni et al (2015) reported temperatures as high as 230 K between June and September of 2014. This very same VIRTIS instrument recorded a maximum temperature of 245 K at 21 Lutetia (Coradini et al (2011)). Furthermore, I have given references that show the Visible and Infrared Thermal Imaging Spectrometer is capable of measuring temperatures in excess of 700 K. Are you saying the VIRTIS instrument is flawed, or unreliable at measuring temperature? Based on what I’ve read, it sounds like an extremely sensitive scientific instrument. What, in your opinion, is wrong with the instruments sensitivity?

    As an aside, recall that the ESA’s Venus Express mission flew the Rosetta mission spare. Knowing this, it seems a great many scientists are impressed by the capabilities of this little instrument!

    You write, “On the surface reaction issue there are no published measurements, that I am aware of, of quantities of oxygen released from the nucleus surface. There are no published measurements either of proton flux density or proton energy close to the nucleus surface so you would have no way of knowing the oxygen yield.”

    Your statements are, once again, false! However, I will give you one point. We do not have “at surface” data for proton densities, and hence, oxygen yields. Regardless, here’s what we do know …

    Instrument = RPC-ICA Reported by Nilsson et al (2015)
    – On 2014/08/07, at 3.6 AU, water ion density was 10^13 molecules/m^3
    – Neutral water ion density on 09/21 is consistent with value reported by ROSINA/COPS
    – At ~28 km from nucleus, comet plasma and SW have comparable particle densities
    – At ~28 km from nucleus, particle density is similar to ‘F’ region of Earth’s ionosphere
    – Solar wind (SW) deflection measured at ~20 deg for protons and half that for He++ ions

    Instrument = RPC-IES Reported by Broiles et al (2015)
    – In a weakly outgassing comet, SW is not slowed by coma, but significantly deflected
    – On 2014/10/20, H+ was deflected 18 deg / He++ was deflected 9 deg
    – On 2015/01/23, H+ was deflected 60 deg / He++ was deflected 30 deg
    – In both cases, deflections are away from sun-comet axis (i.e., away from nucleus)
    – In both cases, pick-up ions are accelerated perpendicular to flow of SW protons

    Conclusion – protons are being deflected away from the comet nucleus. Please note, the deflection of 60 degrees was measured approximately seven months before perihelion!

    In regards to determining proton flux densities, I refer you to a previous comment …

    http://blogs.esa.int/rosetta/2015/03/20/cometwatch-14-march-6-hours-later/#comment-421301

    Now, where are your cited references to show that combustion in a vacuum is even possible? And how does your combustion model account for the increase from 0.3 kg/s (2014/06) to 300 kg/s (recent blog statement 2015/08). That, my friend, is an incredible amount of oxygen!

    You write, “Your oxygen deficiency assertion is an assumption derived from laboratory data.”

    Wrong again! Proton densities within our solar system (at various heliocentric distances, and around numerous planets, moons, etc.) are based on over fifty years of data collected by dozens of science missions. Harvey has also provided us with DSMC proton sputtering rates that are far too low to provide a viable mechanism for oxygen production. We also know that 67P is not made of rock …

    In Rosetta’s encounter with asteroid 21 Lutetia –
    RSI established a mass of 1.7 x 10^18 kg
    OSIRIS determined a volume of 5.0 x 10^14 m^3
    Combined, this data yields a bulk density of 3400 kg/m^3 – i.e., rock

    In Rosetta’s encounter with comet 67P –
    RSI established a mass of 1.0 x 10^13 kg
    OSIRIS determined a volume of 2.14 x 10^10 m^3
    Combined, this data yields a bulk density of 470 kg/m^3 – i.e., NOT rock

    Outgassing rates of water, carbon monoxide, and carbon dioxide cannot be explained by a combustion process that violates the most basic laws of physics and chemistry. The lack of an atmosphere is just one hurdle. And please note, these three combustion waste products all contain oxygen!

    You write, “And figures for oxygen in the coma would represent only unreacted oxygen.”

    Enough said! See above!

    You write, “The nucleus surface is known to be covered with a layer of hydrocarbons, millions of tons and a copious source of hydrogen and if the underlying material is rock there are vast quantities of oxygen available.”

    Again! Please explain the sputtering mechanism that can generate the volume of water cited above using “real” undergraduate physics and chemistry, knowing that protons are being deflected away from the nucleus, and now the scant protons also have to pass through “millions of tons” of hydrocarbons to liberate the oxygen you assume is locked up in rock with a density of 470 kg/m^3. And your “copious source of hydrogen” is …?

    You write, “And the loss of temperature to allow a water reaction product to form ice, surface ice, would occur if the reaction stopped, or stopped and started at a different site.”

    This statement … demands an explanation. Here’s the problem – combustion generates heat. Heat causes the waste products, plus unburned fuel and oxidizer to expand into the “cold” vacuum of space. How then are these expanding water waste products to be deposited on the surface? Can you calculate the velocity of the expanding combustion volume? Can you also calculate the efficiency of combustion (i.e., how much oxygen should be left as a waste product)?

    You write, “We know this occurs but it appears that we have no data on it.”

    No! We do not know that this occurs! Your model/explanation violates basic laws of physics and chemistry! You are stating an opinion that is not based on science.

    You write, “I would argue that ice on the surface is not indicative of ice beneath the surface and I would argue that there is and never has been any evidence that this or any other comet nucleus is ice.”

    Deep Impact! Recall that the spectral signature of water ice (the subject of this thread) is different than that of it’s liquid or gas phases. Water ice was detected at comet 9P by both Earth based and space based observatories (A’Hearn et al (2005), Sunshine et al (2006 & 2007), Schulz et al (2006), Ipatov and A’Hearn (2011)). Apparently the proposed ice-cycle discussed here, requires that water ice exist under the surface. The bulk density of 470 kg/m^3 is further evidence. What kind of evidence would work for you? Sincerely, why are you opposed to comets being composed of volatile ices and dust?

    You write, “But there is no need to argue about these VIRTIS results. There are other ways of getting at the truth, if that is the objective.”

    Actually, that’s what scientist do! Though their ‘discussions’ tend to use mathematics, physics, chemistry, computer models, and ultimately, references, be they textbooks or peer reviewed. And truth is always the objective of science!

    Regarding your last paragraph, the temperatures have already been measured by VIRTIS and reported in papers and on this blog. When the first “jet” images were published, they showed the neck with maximum temperatures of 220 K, not the hundreds or thousands of degrees you are expecting. I will side with you on another point – it would be nice to see something a little more recent. Oh, and the visible jets are entrained dust reflecting sunlight, and the “extraordinarily bright” events include water ice grains being ejected along with the dust. Water vapour is not visible in NAVCAM images.

    • Booth says:

      Correction –
      The first two lines of the RPC-ICA findings list were truncated by the use of common mathematical symbols. The corrected text should read …

      Instrument = RPC-ICA Reported by Nilsson et al (2015)
      – On 2014/08/07, at 3.6 AU, water ion density was less than 10^5 molecules/m^3
      – On 2014/09/21, at 3.3 AU, water ion density was greater than 10^13 molecules/m^3

      Apologies

      • logan says:

        At least a hundred fold on water ion density increase on traversing from 3.6 to 3.3 AU! Amazed at this data, Booth.

        Is there some kind of ‘frontier’ there, physically speaking? Is it just according to the formula?

    • originalJohn says:

      Booth, i am not going to reply to each of your points in turn. You are clearly convinced by your own constructs and interpretation. You are welcome to your opinions. Yours is one interpretation. There are others.

      Let us consider though for a minute your concept of data visualization. The data we are concerned with and which is collected by VIRTIS is a spectrum of (invisible) infrared frequencies. This data is processed and represented by the chosen artificial colour scale of temperature converted from frequency. You describe the colour scale selected as black- orange- white from cold to hottest (your superlative). I would say to be consistent you should say coldest to hottest. At the black and white extremes we are looking at the limits of the scale. There is no
      range of black or white. The orange however (yes, selected for its association with visual perception of heat) covers a range of dark orange to bright (or light) orange and represents the useful range of sensitivity of the scale, with black as a lower single figure limit and white as an upper single figure limit. So all temperatures at or below the lower
      limit will be displayed as black and all temperatures at or above the upper limit will be displayed as white. All that can be concluded from a white indication is therefore a temperature at or above the upper limit, the upper limit of sensitivity of the scale ( not necessarily the instrument).

      It seems that you believe that all temperatures displayed on the scale as white correspond to the single figure upper limit of the scale. What an amazing coincidence that would be, that the upper limit of the scale chosen corresponded exactly to the maximum temperature exhibited at the comet nucleus surface. Of course that would be absurd.

      I will reiterate the reality of the situation. On the scale chosen temperatures displayed as white cannot be known with any precision. The best that could be concluded is that the minimum temperature represented by white is the upper limit of the chosen scale. The maximum temperature represented by white is unknown. And the point at which noorange
      is displayed in the colour is the point of saturation, the point of onset of white. So you have not measured the temperature in the white zone Booth. You have simply measured the minimum temperature it could be.

      The other point I want to comment on is your assertion about availability at the nucleus surface ( at the hydrocarbon/rock interface to be precise) of oxygen to supply a surface combustion reaction, the products of which, if
      the reaction goes to completion, are water and carbon dioxide.
      The source of oxygen is the silicon-oxygen compounds which are the principal constituents of the rock that makes up the
      nucleus. The measured density is anomalous, and in fact anomalous for ice too, so the ice is assumed to be, in the hypothesis, a porous agglomeration of ice and dust. No evidence for this.

      Incidentally, the density of liquid methane is 0.656 kg/ metre cubed and this is probably closely typical of the hydrocarbons coating the surface. So the density of the component of the comet underlying material that contributed to the average measured density would be even lower than 0.4. If all other indications are that the comet is rock,
      mainly, appearance and surface topography, and we have no evidence that it is porous or agglomerated then the density anomaly could arise if the consensus assumption of big G as a constant is flawed. It is assumed it is universal. It may not be. We have no evidence that it is. So the density of the nucleus is no argument that it is not rock.

      The surface reaction depends for its viability on a sufficient supply of oxygen being released from the nucleus rock.
      The suggestion that the nucleus is surrounded by a vacuum is an irrelevance. An atmosphere is not required as an oxygen source. In any event the vacuum idea of space is an obsolete one. Space, the interplanetary medium in this case, is filled with plasma, ions, not a vacuum. And the comet coma is a separate plasma, acknowledged as such now even by the consensus. A significant proportion of those space ions are protons carried in the solar “wind”. There is no dispute
      that this ion stream can be deflected by a magnetic field.

      Rather than measuring the deflected protons the flux density of protons within the coma should be measured, particularly
      close to the nucleus surface. A study then of the background proton density in the solar wind, the density in the coma and the density near the nucleus will expand understanding of the plasma behaviour. The proton energy
      needs to be known too, as a combination the current density and the energy will determine the potential quantity of oxygen that can be released from the nucleus rock. There is no doubt that the protons even at backgound energy levels of 1-10 keV have more than enough energy to overcome the few eV Si-O bond energy.

      There are processes that operate naturally within plasmas and at plasma boundaries that can increase both the proton energy level and the proton current density by many orders of magnitude. On that basis alone it is absurd to assume, as you and others do, that the proton flux and energy available at the comet nucleus surface is that of the background
      level in the interplanetary medium or in the vicinity of the Earth. But even without acknowledging the potential natural increase in current density and energy, plausibility of a surface oxygen/ hydrocarbon reaction can be confirmed or refuted by measuring the density and energy of the proton flux within the coma close to the nucleus surface. Very close. it is likely that a double layer of only metres or even cetimetres in extent defines the boundary between the nucleus and the coma plasma.

      By the way, I remind you that we are picking around at a frontier of knowledge here, sometimes a region where old ideas and interpretations are brought into question and perhaps abandoned, regardless of how widely held they are and regardless whether anything exists to replace them or not.

      • sjastro says:

        @orignaljohn said

        ” If all other indications are that the comet is rock,
        mainly, appearance and surface topography, and we have no evidence that it is porous or agglomerated then the density anomaly could arise if the consensus assumption of big G as a constant is flawed. It is assumed it is universal. It may not be. We have no evidence that it is. So the density of the nucleus is no argument that it is not rock.”

        I’ll let Booth address the rest of the post but this requires a response.
        First of all any “anomaly” relating to G relates more to the experimental error than an actual physical variation..
        The maximum deviation from the mean result in recent times is around 0.7%.
        Even if one accepted this result as “true”, it falls way short of saving your rocky comet model. You would require the anomaly to be around 500%!!!.
        Then there is the problem if G is so wildly fluctuating how was Rosetta able rendezvous with the comet in the first place?
        Even though orbital trajectories are based on computer numerical method programs, G has a specific value.

        • originalJohn says:

          Measurements of G on Earth throughout the 20th century, Sjastro, included differences in result well outside the error range of the equipment. Wild fluctuations is emotive. It is likely there was a reason for the variation. We don’t know it.
          The question is is the assumption that it is a constant valid. There is no evidence that it is. I think it is a very interesting question. You perhaps would prefer to leave it alone and accept what you are told.
          A comet, as an object a long way different from Earth in the spectrum of solar system bodies, is a good opportunity to test the constancy assumption.
          Gravity is dealt with in science as a mathematical concept. Nothing is known about what the force is and how it is transmitted. Not a satisfactory situation at all. To understand how gravity navigation works in the solar system we
          would have to understand what it is, otherwise it is simply empirical luck.

          As far as whether the comet is rock, or what it is made of we should not have to rely on guesswork and an anomalous gravity result. One of the main objectives of the mission surely was to find out, or perhaps prove, what the comet is
          made of, with evidence. It is a pity the lander failed to contribute but is that it. Is there no more attempt to find out what the nucleus consists of. All we have so far is that it looks like rock, it is covered in a layer of hydrocarbons, there are some patches of ice on the surface and the measured density is less than half that of ice. All stuff we pretty much already knew before take off. What do we do now. Keep speculating and wait for somebody else to get the solid data on a future mission.

          • sjastro says:

            originaljohn wrote,

            “Measurements of G on Earth throughout the 20th century, Sjastro, included differences in result well outside the error range of the equipment. Wild fluctuations is emotive. It is likely there was a reason for the variation. We don’t know it.”

            A fundamental flaw in your argument is that you don’t actually know whether a result is due experimental error or not.
            Experiments such as the measurement of G are not performed as single isolated experiments but are coordinated activities between laboratories. Not only is G measured but the repeatability and reproducibility capability of each laboratory is also assessed. In this way one is able to identify if odd results are due to experimental error or not.

            You wrote,
            “The question is is the assumption that it is a constant valid. There is no evidence that it is. I think it is a very interesting question. You perhaps would prefer to leave it alone and accept what you are told.”

            There is evidence (although not conclusive) that G might periodically change in the order of about 0.005% from maximum to minimum but you are deluding yourself into thinking this error is reflected in the density result.
            The minimum density of solid rock is around 2.0g/cc which is a 400% error from the 0.4g/cc.
            The contribution of G as an error to the calculated density of the comet is therefore totally insignificant.

            You wrote.
            ” A comet, as an object a long way different from Earth in the spectrum of solar system bodies, is a good opportunity to test the constancy assumption.”

            As I explained in my previous post if G varies to the degree that you so desperately hope for to address the density issue, the calculated position of the comet would be nowhere near its true position.
            Rosetta would never have reached its target based on the calculated trajectory.
            The fact Rosetta reached its target is a good test for the constancy of G.

            You wrote
            “Gravity is dealt with in science as a mathematical concept. Nothing is known about what the force is and how it is transmitted. Not a satisfactory situation at all. To understand how gravity navigation works in the solar system we
            would have to understand what it is, otherwise it is simply empirical luck.”

            You have got to be joking.

            Physics is divided into 3 types of theories.

            (1) Non phenomenological or cause based theories
            (2) Phenomenological or effect based theories.
            (3) Semi-phenomenological theories .

            Newtonian gravity is a phenomenological type theory. Do you seriously think not knowing how gravity works means the calculations to put men on the Moon, the planetary ephemeris or Rosetta reaching Comet 67P/GC, to name a few, was achieved on empirical luck?

            Give me a break…..

            You wrote,
            “As far as whether the comet is rock, or what it is made of we should not have to rely on guesswork and an anomalous gravity result. One of the main objectives of the mission surely was to find out, or perhaps prove, what the comet is
            made of, with evidence. It is a pity the lander failed to contribute but is that it. Is there no more attempt to find out what the nucleus consists of. All we have so far is that it looks like rock, it is covered in a layer of hydrocarbons, there are some patches of ice on the surface and the measured density is less than half that of ice. All stuff we pretty much already knew before take off. What do we do now. Keep speculating and wait for somebody else to get the solid data on a future mission.”

            What you consider to be “guesswork” is a reflection of your own lack of knowledge.
            You have made this abundantly clear in this and previous posts.

            I’m still waiting on the answers to my questions……

  • Kamal says:

    Sjastro: On this blog we have people with different degrees of comfort with science. What is interesting is how we have a debate between devotees, suspects and skeptics of theory X (with apologies to Higashino), for various X’s. In extreme cases like the electric theory, the devotees try to undermine other theories such as universal gravitation, because refusing to acknowledge its existence is an act of devotion.

    • sjastro says:

      Kamal,

      The line of argument used in this exchange was the classic false dichotomy fallacy.

      If I am a supporter of theory X, and can show that the opposition theory Y is wrong (by fair or foul means), then this automatically validates theory X.

      Hence theory X doesn’t stand on its own merits but on the supposed deficiencies of the opposing theory.

    • logan says:

      Hi Kamal (Lodaya?). Science is build over skepticism.

      Not on my lifetime, but all of the ‘good will’ on ROSETTA will have to be compared, strained and tested against latter planetary science.

      On doing their best on delimiting the nature of their affirmations, Teams are extending the usefulness of their science into the future. [We bloggers don’t have to :)].

      Even today we are adjusting gravitational constant, testing light speed. Personally think the issue is more about attachment and investment.

      • logan says:

        Curious thing: Is trough skepticism that science ‘filters out’ exceptions and preserve general behaviors.

      • logan says:

        Exploring far worlds we are discovering that our assumptions about how a planet(oid) behave where quite ‘exceptional’. Skepticism.

    • originalJohn says:

      Ah yes, the faith argument Kamal. Examine your own beliefs about, for example, the composition and mechanism of comets, the origin of comets and the origin of the solar system. How much evidence do you honestly have. Quite a lot of faith and devotion required there, plus following the majoriy and the consensus. The electric theory of comets is on the other hand a quest for the truth in the face of evidence. No faith required.
      As for gravity Kamal if you know how it works you’re the only one. Quite a lot of trust and faith required there. No evidence of constancy or universality either so all faith there. And the reassuring feeling of being with the crowd of course.

    • originalJohn says:

      First of all sjastro lets get it clear that what I have said about gravity is not an argument. My comments are speculative suggestions to account for the mass anomaly rather than accept that the physical structure of the nucleus could somehow explain the absurdly low density of 0.4. However that does not mean I rule out another explanation or the possibility that other evidence may arise.

      Similarly I am not deluding myself into anything regarding the significance of G results. I remain fully open minded about all possibilities. The fact remains that the range of variation in published results is well outside the error range of the high precision measuring methods used. That is how you know they are variations and not errors.

      What your mind doesn’t stretch to sjastro is that the G variations we are referring to are for measurements on the surface of the Earth, where it would be expected to be constant for a particular body. If G should happen not to be constant then the difference in G for relatively tiny charged body like a comet would be far greater compared to the Earth than the variability on one body. Nevertheless I remind you once again this is speculation. There is no evidence. But there is no evidence that G is universally constant either. Nothing wrong with discussing it therefore. Unless of course you desperately want it to be constant.

      This alludes to my final point. The issues we are discussing seem to be emotive ones for you and you assume they are for me also. So you say ” if G varies to the degree that you so desperately hope for to address the density issue”. Well sorry to disappoint you but I am not at all desperate about the comet density anomaly. i am just interested in an explanation for it and in discussions thereof, emotionless discussions.

      Oh and finally “men on the Moon” as evidence of anything. You are joking there aren’t you.

      • sjastro says:

        originaljohn wrote,

        “First of all sjastro lets get it clear that what I have said about gravity is not an argument. My comments are speculative suggestions to account for the mass anomaly rather than accept that the physical structure of the nucleus could somehow explain the absurdly low density of 0.4. However that does not mean I rule out another explanation or the possibility that other evidence may arise

        Similarly I am not deluding myself into anything regarding the significance of G results. I remain fully open minded about all possibilities. The fact remains that the range of variation in published results is well outside the error range of the high precision measuring methods used. That is how you know they are variations and not errors..”

        The mass anomaly is a creation of your own making. You refuse to accept the evidence because it contradicts your religious and emotional attachment to electric comets.
        If this isn’t a case of self denial then I would certainly like to know what it is.

        In case you didn’t know G=6.67408 x 10^-11+/ 0.00031 x 10^-11 m^3 kg^-1 s^-2.
        This is an 0.005% uncertainty.
        It’s up to you to show that published results outside this range are not due systematic or other errors. You have simply assumed this a physical variation of G and not an experimental error.

        Show me the data you are referring to.

        You wrote,

        “What your mind doesn’t stretch to sjastro is that the G variations we are referring to are for measurements on the surface of the Earth, where it would be expected to be constant for a particular body. If G should happen not to be constant then the difference in G for relatively tiny charged body like a comet would be far greater compared to the Earth than the variability on one body. Nevertheless I remind you once again this is speculation. There is no evidence. But there is no evidence that G is universally constant either. Nothing wrong with discussing it therefore. Unless of course you desperately want it to be constant.”

        Kepler and Newton would be turning in their graves.
        Where do you think Kepler’s laws for planetary motion came from, out of thin air?
        They were based on precise planetary measurements from Tycho Brahe.
        Newton was able to derive the inverse square law for gravity from Kepler’s law and ultimately from Brahe’s data.
        The point here is that G MUST BE A CONSTANT for Kepler’s laws to hold.
        Hence we know in our solar system at least G is constant.
        I don’t know how many times I have to tell you but if G varies Rosetta would never have reached its target.
        Also Rosetta’s orbit around comet 69P/C-G is based on being G being constant.

        My opinion on G being constant is evidence based and nothing else.
        I don’t have an emotional need of G having a particular value, unlike yourself.

        You wrote,
        “This alludes to my final point. The issues we are discussing seem to be emotive ones for you and you assume they are for me also. So you say ” if G varies to the degree that you so desperately hope for to address the density issue”. Well sorry to disappoint you but I am not at all desperate about the comet density anomaly. i am just interested in an explanation for it and in discussions thereof, emotionless discussions.”

        You are being very disingenuous here.
        You are clearly not interested in discussions. You refuse to answer questions, you ignore flaws pointed out in your arguments. Your not even prepared to defend your own position. You repeat the same nonsense over and over again.
        It’s the case of being an EC evangelist trying to gain converts based purely on faith.

        You wrote,
        ” Oh and finally “men on the Moon” as evidence of anything. You are joking there aren’t you.”

        If you cannot comprehend that putting men on the moon is an example of celestial mechanics in operation then that is indeed very sad.

        • originalJohn says:

          Much as you would like me to be, sjastro, I am not an evangelist and I do not represent what you call the EC either. Such assertions are ploys commonly used by your category of person, the consensus believer, when you have no other argument. I am simply considering the facts and the evidence and judging the most likely explanation. I have no desire to convert you. On this blog i am presenting a case to the open minded and perceptive for not believing the hackneyed standard model of comets, for which there is no evidence, and for looking for other explanations. A great deal of evidence for the electrical nature of the interplanetary medium has ensued in the late 20th and early 21st centuries, from NASA sources. Find it if you are interested. Not magic, or belief but observational evidence. People like you object to it because it questions some of their sacrosanct beliefs and the pronouncements of some of their heroes, so they ignore it and pretend that the consensus is the truth. The consensus is being challenged my friend. It is a quest for a true understanding of reality. if you are not interested in that it does not concern me. Stick to the old faith story if you wish but let the truly objective and open minded draw their own conclusions. The consensus of science has been collectively wrong many times in the past and unfortunately with regard to comets and cosmology it looks as though it is too in our era and you appear to be a voluntary victim of the ignorance.

  • Booth says:

    Originaljohn!

    Apologies for the delay!

    Re. your comment of 06/10/2015 at 19:43

    You write, “Booth, i am not going to reply to each of your points in turn.”

    I really wish you would! The fact that you will not discuss the points I raise is an indication that you have no science to draw on! For example, using basic physics and chemisty, please explain the difference between the 21 Lutetia density of 3400 kg/m^3 and the 67P density of 470 kg/m^3. You can’t! You simply call the 67P density anomolous! What does that mean? There must be something wrong with the instrumentation? There must be something wrong with the scientists? There must be something wrong with the physics? I ask with all sincerity, what is the issue? Asteroids are made of rock! Comets are made of ices! There is no anomaly with the density! Just your expectation of what it is supposed to be to prove your point. A point, I might add, that has no scientific basis. When you realize that comets are made of ices, all the pieces fit together!

    Further proof?

    Table 1: A Short List of Comet Bulk Densities
    Comet: MT : Visited : Eccen : Density (kg/m^3)
    1P : FB : 1986/03/14 : 0.967 : 600 – Halley
    9P : IM : 2005/07/04 : 0.517 : 620 – Tempel 1
    19P : FB : 2001/09/21 : 0.624 : 300 – Borrelly
    67P : ES : 2014/08/06 : 0.641 : 470 – Churyumov–Gerasimenko
    81P : SR : 2004/01/02 : 0.538 : 600 – Wild 2
    103P : FB : 2010/11/04 : 0.694 : 220 – Hartley
    MT = Mission Type with FB = Flyby, IM = Impact, ES = Escort, SR = Sample Return

    Table 2: A Short List of Asteroid Bulk Densities
    Aster: MT : Visited : Eccen : Density (kg/m^3)
    1 : ES : 2015/03/06 : 0.076 : 2160 – Ceres(C)
    4 : ES : 2011/07/16 : 0.088 : 3456 – Vesta(V)
    21 : FB : 2010/07/10 : 0.164 : 3400 – Lutetia(M*)
    433 : ES : 2000/02/14 : 0.223 : 2670 – Eros(S)
    9969 : FB : 1999/07/29 : 0.431 : 3900 – Braille(Q)

    Table 3: A Short List of Planet Bulk Densities and Basic Snow Line Properties
    Planet : R(AU) : T(K) : Eccen : Density (kg/m^3)
    Mercury : 0.387 : 450 : 0.206 : 5430
    Venus : 0.723 : 329 : 0.007 : 5200
    Earth : 1.000 : 280 : 0.017 : 5520
    Mars : 1.524 : 227 : 0.093 : 3930 – ‘Rocky’ planets inbound
    Jupiter : 5.203 : 123 : 0.048 : 1330 – ‘Ice or Gas’ planets outbound
    Saturn : 9.539 : 92 : 0.056 : 687
    Uranus : 19.18 : 64 : 0.047 : 1320
    Neptune : 30.06 : 51 : 0.009 : 1640
    Note 1 – Tabulated temperature data is based on solar heat flux at the planet’s average distance from the sun.
    Note 2 – Asteroids are mainly found between Mars and Jupiter. Comet sources are typically located well beyond Neptune. Note the temperatures associated with these regions!
    Note 3 – The observed solar system water snow line is ~2.7 AU. Inside this region, comets (which are made of volatile ices, especially water) will experience extensive sublimation. Outside this zone, sublimation will still occur, but it will be driven by volatiles with lower sublimation temperatures! That is real science! And it’s all so simple!

    Fun Fact – The bulk density of the Earth is 5520 kg/m^3. The Earth is composed of several different layers with unique densities, that when “summed,” equals that of the bulk density. At the surface, the density of Earth’s continental crust is ~2700 kg/m^3, oceanic crust is ~3000 kg/m^3, and at the Earth’s inner core, it is estimated to be ~13000 kg/m^3.

    Query – How do you explain the density of Saturn? Tis comparable to that of comets!

    While statistically not significant (i.e., the sample size is too small), we can still see that asteroids and comets have different densities. It is also worth noting that comets outgas water, carbon dioxide, carbon monoxide, and large quantities of dust. Asteroids do not! Furthermore, you can see that the two types of objects exhibit a wide range of eccentricities – I deliberately included that data point knowing that that is supposedly important to the EU model (FYI, it is not). Now, in light of all I have given you, please explain 1996 PW – a rocky body (i.e., no outgassing) with an extremely high eccentricity of 0.9903! And just for the record, 1996 PW’s perihelion distance is 2.55 AU (i.e., inside our solar system’s water snow line). I love science!!!

    The models I spend my time researching are internally consistent! I’ve yet to see any sort of consistency in your EU model. Asteroids are rocky bodies with relatively small amounts of frozen volatiles. Comets are primarily made of volatile ices that sublimate when exposed to a heat source. As I’ve pointed out in another thread, sublimation of water ice occurs at specific temperatures as the ASW anneals, releasing other volatiles with lower sublimation temperatures. The early outgassing activity observed when 67P was between 4.3 and 3.7 AU is consistent with the comet experiencing temperatures between ~135 and 146 K (i.e., water ices annealing and/or converting to cubic form).

    If your model cannot explain the density difference between asteroids and comets using real physics, your model FAILS and must be discarded! That is how science works. Claiming the laws of physics must bend to suit some unrealistic, ill-conceived hypothesis is absurd! If you want to claim that the value of the gravitational constant is variable, you need REAL SCIENCE to prove it! Enough said!

    Query – If it’s called the “gravitational constant,” why do you think it’s variable?

    Next, you write, “You are clearly convinced by your own constructs and interpretation.”

    No, Sir! I am convinced by science, evidence and logic! EU/EC understands none of this. Case in point, sublimation of cometary materials has been extensively researched. First, I would like you to review the excellent summary by Sears, Kochan, and Huebner (1999 – and references therein) regarding the KOSI (German = Kometen Simulation) experiments conducted between 1987 and 1993. As an aside, you may be horrified to learn that young children are making their own simulated comets inside a DLR test assembly – and these comets are made of ices and dust. If this is not convincing enough, you can consult the excellent works of scientists such as Bar-Nun, Laufer, Kleinfeld, Mumma, Notesco, and Prialnik! If you would accept some guidance, I suggest you start with Akiva Bar-Nun’s extensive library! Top notch stuff!

    KOSI Summary = Sears, Kochan, and Huebner; Laboratory Simulation of the Physical Processes Occurring on and Near the Surfaces of Comet Nuclei; Meteoritics & Planetary Science 34, 491-525 (1999)

    You write, “Let us consider though for a minute your concept of data visualization. The data we are concerned with and which is collected by VIRTIS is a spectrum of (invisible) infrared frequencies.”

    I am so glad you brought this up. I’ve been wanting to discuss this issue for some time. To begin, the human eye evolved to register EM spectra in the very narrow range of ~380 to 720 nm. So, why is this important? Our Sun can be modeled as a blackbody with a temperature of ~5800 K. Using Wien’s Displacement Law, this temperature yields a spectral emission peak of ~500 nm (i.e., within the green region of the spectrum), which coincides with the peak sensitivity of the human eye! Now, given the range of the EM spectrum from gamma rays (at less than 10 pm) to longwave radiation (at greater than 10 km), we are essentially blind to the incredible beauty of our universe. Hence, when you say 67P “looks” like rock, I would ask you to “look” at all the data to ensure your eyes are not deceiving you. If you’re still confused, use your favourite search engine to enter the key words, “fake prop rocks and boulders,” and tell me what you see. You can be sure that science instruments like ALICE and VIRTIS can see right through that deception. NAVCAM? Not so much. The human eye? Again, not so much …. Clear as mud?

    Query – Why is the term “invisible” significant? Infrared EMR may be “invisible” to the human eye (a rather useless sensing organ – see above), but it is not invisible to our technology!

    If you’ve not explored Rosetta’s extensive array of scientific instruments, many operating outside the optical range, I give you the following summary list …
    NAVCAM : optical navigation camera : ~380 to 720 nm
    ALICE : ultraviolet imaging spectrometer : ~70 to 205 nm
    OSIRIS/WAC : multispectral camera : 14 specific filters : ~245 to 630 nm
    OSIRIS/NAC : multispectral camera : 11 specific filters : ~270 to 990 nm
    VIRTIS-M : visible and IR imaging spectrometer : ~250 to 5000 nm
    VIRTIS-H : high resolution N/M IR spectrometer : ~2000 to 5000 nm
    MIRO : microwave inst : centre-band freqs : 0.5 mm (562 GHz) & 1.6 mm (188 GHz)
    RSI : radio science inst : X-band @ 36 mm (8.4 GHz) & S-band @ 130 mm (2.3 GHz)
    CONSERT : radiowave nucleus transmission : ~3330 mm (90 MHz) – a variation on GPR

    You write, “This data is processed and represented by the chosen artificial colour scale of temperature converted from frequency. You describe the colour scale selected as black- orange- white from cold to hottest (your superlative). I would say to be consistent you should say coldest to hottest.”

    You slay me, Sir! Well, not really! This is exactly what I expect of EU proponents – don’t discuss the data or science, attack a trivial issue with an individual’s use of language. For the record, my background is in science and engineering. What about yourself? Perhaps a degree in English? I do ask sincerely.

    You write, “At the black and white extremes we are looking at the limits of the scale. There is no range of black or white. The orange however (yes, selected for its association with visual perception of heat) covers a range of dark orange to bright (or light) orange and represents the useful range of sensitivity of the scale, with black as a lower single figure limit and white as an upper single figure limit. So all temperatures at or below the lower limit will be displayed as black and all temperatures at or above the upper limit will be displayed as white.”

    You, Sir, are still wrong! Your explanation and interpretation of the data indicates to me that you have no background in science. When presenting data, scales are chosen to include the minimum and maximum values in a data set. If there are outliers, the scale and/or text should explain/identify the situation. Again, the black-orange-white scale in question is a standard used by scientists in many different disciplines. There are also dozens of colour scale variations, and several ways in which to display no data, as well as over-scale and under-scale data. I give you the following three temperature maps. If you feel the data being presented is misleading or flawed, please explain why! I would really like your thoughts on this issue!

    Venus Express #1
    http://www.esa.int/spaceinimages/Images/2006/12/Temperature_maps_of_Venus_surface

    Please note that the scale runs from “black to red,” with a minimum VIRTIS temperature of 726 K and a maximum of 746 K. I also want to draw your attention to the white area in the SE corner of the VIRTIS map. You will note that there is NO white temperature value on the scale provided. This is one way scientists display off-scale, or over-scale data; what you have been calling saturated. Furthermore, there are two different kinds of “black” data. According to the figure description, the VIRTIS data was acquired on a single orbit over the south pole, resulting in a large area of “no data” covering most of the planets surface. This is obvious. Yes? There are also at least three small regions where it is obvious that the temperature being recorded is ~726 K (taking into account appropriate instrument error).

    Venus Express #2
    http://www.esa.int/spaceinimages/Images/2009/07/The_new_temperature_map_of_Venus_southern_hemisphere

    Again, I draw your attention to both the temperature scale and the map. In this case, the authors are showing a positive correlation between surface lower atmosphere brightness temperature and Magellan altimetry data. The scale indicates that temperatures range from 695 K (at topographic altitudes greater than ~3 km) to 715 K (at altitudes ~1 km below the VIRA datum). It should be obvious by inspection that there are two different “off” scale conditions being presented. First, the black hachures indicate missing altimetry data. Next, the white regions at the pole and on the right side of the map are not areas of saturation, but areas in which no data was collected. Please see Mueller et al (2008) for more detail. As an aside, the white area in image #1 (based on data from a single orbit) was located at approximately 270 E x 37 S. This same area corresponds to a temperature of ~705 K in the current image (based on data from over 100 orbits).

    Venus Express #3
    http://onlinelibrary.wiley.com/doi/10.1029/2008JE003075/pdf

    Apologies in advance. I tried to find a standalone image for our discussion, but came up empty. On the plus side, you get to see the whole set! Referring to Figure 10 (from Grassi et al (2008)), you will note the scale being used is our old friend “black-orange-white.” In this case, the authors were kind enough to spread the air temperature scale out from 170 to 300 K (they did this to aid future comparison between all the data sets that will have temperatures within that range). When you examine the images in Figure 10, you will observe air temperature values that range from a low of ~215 K to a high of ~245 K. Perhaps this specific form of scaling is less confusing than the simple min/max system being employed by the Rosetta VIRTIS team. Thoughts?

    I could go on for hours … but I won’t! You can look up temperature maps from the Lunar Reconnaissance Orbiter, annual surface air temperatures on Earth, climate change related temperature deltas, etc!

    Query – If “all temperatures at or below the lower limit will be displayed as black and all temperatures at or above the upper limit will be displayed as white,” why not select a temperature scale that actually includes the minimum and maximum temperatures measured? Why use a convoluted, ill-fitting, non-standard scale that makes it difficult to interpret the data?

    You write, “All that can be concluded from a white indication is therefore a temperature at or above the upper limit, the upper limit of sensitivity of the scale (not necessarily the instrument).”

    No! When I review the data as presented, I observe a maximum temperature of ~210 K over the three days of ice cycle data. No conclusions are necessary or warranted regarding some unmeasured maximum. The temperature data is what it is! Furthermore, the “water ice abundance” data is what it is. What we may debate is the relationship between temperature and water ice abundance. In my opinion, humble as it is, the conclusions being drawn by De Sanctis et al are reasonable!!! Please note, that last statement received three exclamation points!

    Query – How can scales be sensitive? Scientific instruments are sensitive. Some people are sensitive. But referring to a scale as being sensitive? No! Scales are cold and cruel. They offer a “black and white” view of the data! There can be no questioning the scale! Data? Methodology? Certainly! But you often need to understand the science and mathematics to find the errors and flaws – hence, the “peer” review!

    You write, “It seems that you believe that all temperatures displayed on the scale as white correspond to the single figure upper limit of the scale.”

    No! You are obviously confused on how scales are selected and applied to data! As I’ve stated previously, any pixels displayed within the range called “white” are between 200 and 210 K. Why is that so hard to grasp? The maximum temperature measured over the three ice cycle days in question was ~210 K (plus or minus some instrument error) As it turns out, the maximum temperature reported in this thread is well below the maximums reported elsewhere! For example, Capaccioni et al (2015) reported temperatures at 67P as high as 230 K between June and September of 2014. This very same VIRTIS instrument recorded a maximum temperature of 245 K at 21 Lutetia in 2010 (Coradini et al (2011)). If VIRTIS can record temperatures up to 245 K, and the temperature in the ice cycle data set never exceeds 210 K, why not choose a temperature scale that best represents the measured data? Restated, the scale for the data in this thread was deliberately chosen to constrain the minimum and maximum temperature values contained within the current data set. To a scientist this is trivial!

    You write, “What an amazing coincidence that would be, that the upper limit of the scale chosen corresponded exactly to the maximum temperature exhibited at the comet nucleus surface. Of course that would be absurd.”

    Wrong again, and I must admit that I am getting tired of saying that! Amazing coincidence? Not at all! As noted in Venus Express #3, it is possible to select a scale that bounds the minimum and maximum data values with buffers on either end. In the ice cycle case, there are no buffers. Contextually, your use of the word “chosen” is salient to our discussion. The scale for data presented in this thread was “chosen” by scientists! They deliberately “chose” to set the scale maximum to be equivalent to the maximum temperature measured (aside – sometimes this is automatically done by the software being used). Whatever the motivation, setting the maximum scale value to be that of the maximum measured temperature does not alter the meaning or importance of the data! To scientists, this entire discussion of scale “saturation” and “sensitivity” is irrelevant! Instrument can be saturated. Scales cannot. Instruments can be sensitive. Scales are not.

    You write, “I will reiterate the reality of the situation.”

    Sadly, I don’t think so. From what I can gather, the electric universe is far removed from reality. As it turns out, there are dozens of physical laws used by practicing electricians that seem to have absolutely no place in the electric universe. Why is that? Will we ever see a circuit diagram for the operation of comets, asteroids and 1996 PW? Are you familiar with what are referred to as Main Belt Comets? And then there’s simple electrodynamics (please see Griffiths – Introduction to Electrodynamics (Fourth Edition – 2013)).

    You write, “On the scale chosen temperatures displayed as white cannot be known with any precision. The best that could be concluded is that the minimum temperature represented by white is the upper limit of the chosen scale. The maximum temperature represented by white is unknown. And the point at which no orange is displayed in the colour is the point of saturation, the point of onset of white. So you have not measured the temperature in the white zone Booth. You have simply measured the minimum temperature it could be.”

    Once again, a thousand times wrong! As I have tried to explain in my long winded entries, we can, and do know, “precisely” (within error tolerances, of course) what the maximum temperature is. If the temperature was 230 K, the scale would be set to include that value as the maximum. If the temperature was 245 K, the scale would be set to include that value as the maximum. If the temperature was 700 K, the scale would be set to include that value as the maximum. If the temperature were truly anomalous, the scientists would be obligated to identify this discrepancy and try to explain it. As there are no anomolous temperatures, this has not been the case. For the record, there are numerous examples in the literature where errant data is discussed by researchers. It happens all the time. But back to your issue with “white” being equivalent to “saturation” …

    For the three days of ice cycle data, the maximum temperature measured was ~210 K (plus or minus some systematic instrument error). That is what the scale tells us. And in case it was not obvious, I don’t have a problem with that number. It is consistent with expected temperatures in regions of icy comets exposed to insolation at ~3.3 AU from the Sun. Now, at the time the ice cycle temperatures were being measured, Capaccioni et al (2015) was observing temperatures no greater than 230 K in isolated, high incidence angle hotspots. Let me restate that … the maximum temperatures being measured at 67P between June and September of 2014 never exceeded 230 K. The maximum temperatures at 67P in the specific region under ice cycle investigation never exceeded 210 K. As has been shown many times, this specific instrument has already measured temperatures as high as 245 K (i.e., well below the VIRTIS “saturation” temperature). Furthermore, this exquisite piece of scientific kit is able to measure temperatures in excess of 700 K (i.e., well below the VIRTIS “saturation” temperature)! So, what is the “saturation” temperature for VIRTIS?

    As stated long ago, mineralogical calibrations for VIRTIS on Venus Express were conducted using a reference temperature of 770 K, a temperature which is ~35 K higher than the VIRA reference temperature! And still no saturation! Here’s a fundamental truth about many scientific instruments – if the signal being measured is extremely strong, you reduce the integration time to avoid saturation. Bringing the concept closer to home, when the sky is clear and the sun is shining, photographers can reduce the amount of light entering their camera in one of two ways. They can either stop down the aperture, which has the added benifit of increasing the depth of field, or they can reduce the integration time by decreasing the shutter speed. So, what is the “saturation” temperature of VIRTIS? I’ll wager that it is significantly higher than 770 K! And I certainly don’t think we will see any VIRTIS temperatures on, or around, 67P greater than ~400 K.

    I would really like to think that the issue of anomolous temperatures has been explained satisfactorily, but alas ….

    I fear that no matter how much evidence I put forward, you will continue to cling to the notion that the VIRTIS temperatures being measured and presented are in error. The scientists are obviously withholding critical information that would validate the electric universe’s system of beliefs. Guess what? There is no conspiracy! There are no anomalous temperatures! The data is accurate and well presented! The fact that VIRTIS has measured temperatures up to 245 K on asteroid 21 Lutetia should be your first clue that you have been wrong in your interpretation of what is happening on and around 67P. Comets are made of ices! The data is consistent with that fact!

    Originaljohn, if you believe Rosetta instruments are broken, why do you keep posting on this weblog? RSI is broken because the density is wrong. VIRTIS is broken because it is saturated and cannot measure temperatures above 700 K. Please, show me one piece of real evidence from the Rosetta mission that you accept as fact (and the volume of the comet nucleus obtained by OSIRIS does not count). Sincerely, I would like your feedback on this issue. What Rosetta data do you accept as fact? What Rosetta data does EU accept as fact? As far as I can tell from past readings, the answer will be none. I hope that I am wrong.

    Part 2 will follow shortly ….

    • originalJohn says:

      Well Booth, I appreciate your detailed and considered reply and acknowledge the time and the work that you put into it. I have some idea of how all consuming it can be. I have not yet looked at all your linked references but I will. I am interested in this topic of temperature measurement in “space”.
      Let us get one thing clear though. I do not represent the EU paradigm. Any ideas I proffer are based on my own judgement and my own studies, which of course includes the work of those identifiable as representing EU theory. Neither will I disclose my background, education or any personal details. I am represented entirely by what I say. I am not looking for a job or any sort of approval. Similarly I am not either interested in your background , qualifications or status, just in what you say. And from that I conclude that you are an insider. ESA are your employers so there is a limit as to how far you can go in straying from the straight and narrow, the consensus view. I would advise you Booth however that you could, in this comet instance and on the issue of temperature alone, be foregoing a big opportunity to make a name for yourself, but perhaps you do not have the power and can’t risk it.

      Once again I am not going to pick through your reply point by point. I prefer to read the whole thing and comment on aspects which make an impression. I do not deliberately ignore any issue and if I had no reply I would say so. If I later realised I was wrong I would say so too, as I have done before on this blog. In other words I am not trying to fool anyone or get away with anything. My reply will not in any event match the length of yours but I am happy to return to any issues in future posts. For now look upon it as a precis.

      To begin with we are discussing the issue of choice of scale and I get the impression from all you say that you assume, for the VIRTIS temperature plots, that the data is received and then the scale is applied depending upon the range of the data. I on the other hand, and you will correct me if I am wrong, assumed from reports that VIRTIS M is a camera type instrument, an imaging spectrometer, and that the scale is built into the instrument before the data is gathered, as in a camera, hence my notion of saturation, synonymous with overexposure. In other words how the received signal affects the VIRTIS imaging device is what indicates the temperature. My question to you would be If you were to point the VIRTIS camera at the Sun, from an appropriate distance, with exactly the same configuration as was used for the comet what would be recorded on the image.

      You see Booth I have very good reason to expect much higher temperatures at the comet surface than you have recorded, and you have in your view very good reason to believe the reported temperatures because you believe the comet is ice sublimating gas. Neither of our very good reasons should however influence what the instrument detects. If it is truly sensitive to a temperature range which includes both our expectations then the result should discount one or the other. If however the instrument as you suggest has a limit of around 700 deg K then it is no use for detecting temperatures of say 5000 deg K and cannot discount them.

      On the question of the density comparison between comets, asteroids and planets which you raised I would remind you that there is a major significant factor which affects these bodies and that is the shape of their orbits. In fact there is more similarity between the asteroids in general and planets, both of which approximate to circular orbits, than between asteroids and comets. Comets have highly elliptical orbits. So no surprise that asteroids return rock like densities as do the Earth and other acknowledged rocky planets. Comets on the other hand despite appearing to be a rock bodies and returning rock mineral results when ejected material is analysed, exhibit a distinctly unrocklike density, in fact distinctly unicelike density too. The response of the established scientific community to this result has been to assume a highly porous physical structure of as yet unknown material but assumed to be ice as it is closer to the result in density. Nevertheless that is why it is an anomaly. That assumption is invalid. It does not make sense. Not because I don’t want it to. I am entirely objective about it..

      Interestingly no composition results yet on this comet on analysis of ejected solid material, yet the Rosetta craft is right there. The NASA Stardust mission went to great trouble solely to collect samples of ejected solids from comet Wild 2 and found it to consist of complex rock minerals that we are familiar with on Earth, some of them only capable of formation at extremely high temperature.

      So there is objective reason to think the comet is rock not ice and that the density is an anomaly. There are in my view three possible explanations. 1. It is highly porous material, higher porosity than any known pumice on Earth for example. 2. It is normal rock density material but formed as a thick shelled hollow structure. Perhaps a shell wall of a couple of hundred metres. Just a guess. I have not calculated if this would account for the density. We are looking for a reduction in mean density to about 14 % of solid rock density. 3. There is something wrong with our understanding of mass with regard to specifically comets. In other words the comet is solid rock but does not manifest a solid rock mass as would be expected from a universally constant big G. A possible explanation for this would be a result of the elliptical orbit of the comet. Without going into detail here ( I have done elsewhere on this blog) there is a plausible mechanism relying on electrostatic induction and an electrodynamic charge by which the comet acquires a charged state. As gravity ( an unknown mechanism in physics) could feasibly be a charge interaction phenomenon between polarised states of bodies ( other peoples theories not mine) it is possible that the charge state of a body could account for the mass it manifests.

      I am very interested in option 3 as an explanation although clearly have no way of gathering evidence. That is the unique privilege of the Rosetta team. They actually have an opportunity of explaining the mysteries of comets and gravity in one fell swoop. Perhaps the peers would not approve. But science is not a democracy. Progressive ideas are never popular.

      You could see I am sure Booth that the discharge of this acquired charge could readily also explain the observed behaviour of comets. It implies also that the mass might change with state of charge.
      You could see also I am sure why the temperature at the nucleus surface is significant. An arc discharge would exhibit a temperature of 5000 deg K plus, a glow discharge combined with combustion around 1200 deg K and an ice sublimation perhaps 150 to 270 deg K. Very large differences and easy to separate. An irresistible measurement to an objective scientist I would have thought.

      By the way finally I have no dispute with the functioning of the Rosetta instruments. I think the density and therefore the mass is correct and I am happy the VIRTIS camera is working as designed. I am however questioning the interpretation in both cases.

  • Booth says:

    … Part 2

    originaljohn!

    I am going to make every effort to keep this post shorter. No promises though, as there is so much interdisciplinary science to discuss. And it does actually relate to the water ice cycle!

    Re. your comment from 06/10/2015 at 19:43 (continued …)

    Now. I would like to jump ahead in your commentary to deal with what I consider to be the most important failure of the EU model.

    You write, “The measured density is anomalous, and in fact anomalous for ice too, so the ice is assumed to be, in the hypothesis, a porous agglomeration of ice and dust. No evidence for this.”

    Actually, the evidence is overwhelming! As I mentioned in the previous post, our eyes are rather useless for sensing much of what our universe is made of and how it operates. For example, our eyes cannot sense the chemical signatures of poisons in plants, nor can they see the tiger hiding in the dark. And have you ever gone scuba diving below 10 m in natural sunlight? That 380 to 720 nm optical window really narrows towards the blue end of the spectrum! Hence, when we employ advanced sensing technologies to enhance our sight, the evidence for comets being made of ices is actually quite overwhelming! Please refer to Figure 5, from A’Hearn et al (2011) for just one tantalizing example!

    But back to the bulk density. This, in my opinion, is the one issue that must be resolved. Your whole house of cards rests on this foundation. Refering to Tables 1 and 2 from my previous post, you will note that comets and asteroids have very different densities. You will also note (refering to Table 3 – same post), that the planets have a density dividing line somewhere between Mars and Jupiter. Inside this dividing line, we have the rocky planets and asteroids. Outside this line we find the “gas” giant planets, as well as the reservoir regions for comets (i.e., the Kuiper Belt and Oort Cloud). This dividing line is refered to as a snow line, and each volatile species has it’s own unique (temperature) distance from the Sun. Inside it’s snow line, the volatile molecule will sublimate. Outside it’s snow line, the same volatile will deposit (i.e., the phase change from gas to solid).

    Now, the bulk density of asteroid 21 Lutetia is 3400 kg/m^3. The bulk density of comet 67P is 470 kg/m^3. These values were established using the same physical RSI and OSIRIS assets. It should also be obvious that asteroids and comets are made of common materials (i.e., atoms consisting of protons, electrons, and neutrons; nothing exotic), and exist within a well defined physical reference frame (i.e., normal physical processes are at work; the flight dynamics team was able to use four gravity assist maneuvers to rendezvous with 67P, and knowledge of the local gravity field (which is a function of mass) to maintain stable and predictable flight operations around the comet nucleus). According to Table 3 (Sears et al (1999)), the KOSI comet simulant from experiment #8 had a true density of 400 kg/m^3 and a porosity of 56%. If you look at the composition of the comet simulant for this experiment you will see that it is composed of nothing but water. No dust. No other volatiles. Just water! Thus, it should be obvious that the bulk density of 67P is indicative of a comet composed of a significant amount of water ice. Again, there must be other materials in the mix to account for the outgassing and dust production, but we are essentially on the right track. Clear?

    Aside – All the measured densities from the KOSI experiments fall within the range of comet densities listed in Table 1 (from previous post).

    Query – You claim the density of 67P is anomalous. If true, then the densities of all comets are anomalous! The measured densities from all eleven KOSI experiments are anomalous. And finally, by extension, the densities of the four outer planets must also be anomalous! Why, then, is everything on the outbound side of the snow line anomalous? The “sublimation” model says that all these “anomalous” objects have a density that is consistent with a composition of volatiles at low temperatures! What makes this detective story so interesting and exciting is determining the exact composition of each individual object! The research on comet composition is quite extensive and easy to locate on the internet! Take a few hours and check it out.

    Your turn, Sir! Where is your physical EVIDENCE (chapter and verse) that supports the absurd EU claim that the density was incorrectly measured, and hence, casts genuine doubt on what I have presented here? Please note, personal opinion and conjecture will not do! I want cited references! I want real science … and calculus! Lot’s of integral calculus! And juicy physics equations! I assume that most of the laws of physics still work in the electric universe? Now, if you want the science community to see the EU model as a credible alternative (and not some bad religion), you need to use the same scientific rigor you demand of the science community!

    Conclusion – The density and sublimation evidence is before you (and I can supply you with hundreds of additional papers if need be), you just refuse to accept the cumulative results produced by thousands of scientist over the last 2000 plus years, or the hard data reported by the Rosetta science teams! Remember, the bulk density of 67P has been established by Rosetta’s RSI and OSIRIS teams to be 470 kg/m^3. This density is not anomalous. This density is consistent with KOSI results, comet formation models, and the accretion model of planetary formation. It is not, however, consistent with EU “non-science” ….

    Query – If comet densities are anomalous, how come EU proponents are the only ones to see this? If I may offer a thought, I don’t think the problem is with the physics surrounding comets!

    Jumping ahead …

    You write, “If all other indications are that the comet is rock, mainly, appearance and surface topography, and we have no evidence that it is porous or agglomerated then the density anomaly could arise if the consensus assumption of big G as a constant is flawed. It is assumed it is universal. It may not be. We have no evidence that it is. So the density of the nucleus is no argument that it is not rock.”

    Now, you’ve only listed one “visual” indication that the comet MAY be made of rock – that of appearance. Is that really sufficient evidence to be presented in the scientific court of law? I don’t think so! As shown previously, the human eye is not a reliable scientific instrument in this environment. Our eyes can be deceived. What we “see” is not necessarily what is “physically” there. Going forward, visual evidence will no longer suffice in this court! To prove your claim we need samples in hand! Actual physical evidence! Is this not the same basic demand you make regarding the evidence of ice? The EU mantra drones on – Because we “see” no ice, there is no ice! While the “appearance” of 67P may “look” like rock, the bulk density determined using RSI mass indicates a composition of porous ices and dust. This detail has also been materially confirmed with the KOSI experiments (i.e., densities ranging from 400 to 600 kg/m^3, and porosities running from 29 to 60%). Rosetta is providing the evidence that 67P is made of ices and dust, you deliberately choose to ignore or deny the great work being done by all the scientists involved. For shame, Sir!

    Summation – There is no density anomaly! Your model is flawed! Your model collapses if 67P is made of anything other than rock. The scientifically measured density (as well as other Rosetta instrumentation) indicates that 67P is not made of rock, but low density ices and dust with a reasonably high porosity. This is internally consistent! You cannot continue to make this unsubstantiated claim without real physical evidence! Hell, any kind of evidence from EU would be a pleasant surprise!

    Aside – Surface topography is far to vague to be used as evidence of rock or ice as both compositions can generate the noted features seen on 67P. Dead end! Carrying on …

    Let’s talk about your understanding of Sir Isaac’s big “G” in the context of the real world! You know, the one we live in? Newton’s law of gravitation states that the force of attraction between two objects is proportional to the product of their masses, and inversely proportional to the square of their distant. The constant of proportionality, G is refered to as the universal gravitational constant. Now, strictly speaking, the law of gravitation only applies to point masses. To find the total attractive force between two large bodies, we need to add up the vector forces that each particle in mass one exerts on each particle in mass two. To solve this problem, Newton developed integral calculus!!!

    So, is G a universal constant? As relates to Rosetta, we know that G has been critical to the flight dynamics team for both rendezvous and normal day-to-day operations around the comet nucleus. The successful rendezvous alone required four gravity assist maneuvers past Earth (x3) and Mars (x1). The flights of Voyager 1, Voyager 2, and Ulysses (just three of several hundred) required an intimate knowledge of celestial mechanics (i.e., calculating the location of a planetary mass) and how gravity effects the trajectories of spacecraft! Furthermore, we could not have ventured to the moon and back without a stable and reliable value of G. We also observe predictable gravitational interactions between billions of astronomical objects at distances both near (e.g., our solar system) and far (e.g., galaxies and galactic clusters). Of course, the most telling example of constancy is the presence of stars, planets, asteroids and comets – objects made of individual point masses held together by the force of gravity! Thus (and I think you’ll agree), there is sufficient qualitative proof that G is constant on the Earth, the moon, our Sun, and finally … 67P!

    But obviously this is not the whole story! Is there evidence that G changes over time and/or space? Anderson et al (2015) looked at the last dozen Earth based experimental measurements of G and found that the results, do indeed, vary with time! Curve fitting showed that the values of G exhibited an oscillatory behavior with a period of 5.899 +/- 0.062 years, and an amplitude of 1.619 +/- 0.103 x 10^-14 m^3/kgs^2. The researchers are not suggesting “… that G is actually varying by this much, this quickly, but instead that something in the measurement process varies.” One natural periodic process they found that fits the data is Earth’s “Length of Day” (ref. Figure 1) (statistical significance = 0.9976, assuming no phase difference). For completeness, the authors also include a calculated weighted mean value for G = 6.673899 +/- 0.000069 x 10^-11 m^3/kgs^2! Now, does this seem like another positive endorsement for the constancy of the gravitational constant?

    But wait … there’s more! Zhu et al (2015) used the precise timing associated with binary pulsar J1713+0747 to determine the rate of change for the gravitational constant. In this 21-year experiment, “delta G/G” is found to be 0.6 +/- 1.1 x 10^-12 yr^-1 (95% confidence), and changes at least 31x slower than the average expansion rate of the universe. The authors describe this value of “delta G/G” as being “consistent with zero!” In other words, the rate of change is so small that it does not register on cosmological timescales. Sounds rather constant, don’t you think?

    So what have we learned? There is no anomalous density! There is no anomalous gravitational constant! Big G does not appear to change on cosmological timescales! It’s experimental determination does, however, appear to be impacted by some variability associated with the Earth’s structure and composition! An exciting mystery to a scientist!!!

    In conclusion, let me turn your words around for a different perspective … The density anomaly must exist because the EU/EC model is unable to function if the comet is made of ices! The coping mechanism is to assume that the gravitational constant IS WRONG because EU needs it to be! Not because it is! Planting your head in the sand blinds you to the evidence before you!

    And the Rosetta evidence is before you! However, as long as you clinging to the shards of your failed hypothesis, you will never grow your knowledge of the natural world. Tis your lose!

    Query – Why does the assumed EU variability of G produce a bulk density that is lower than that of rock? I would expect your “science” to predict a bulk density that changes with perihelion distance due to changes in charge! EU is an utter failure! I see no predictive capabilities! Why has the bulk density of 67P not changed?

    References:

    1) A’Hearn et al – EPOXI at Comet 103P/Hartley 2; Science 06/2011; 332(6036):1396-400.

    2) Anderson et al – Measurements of Newton’s Gravitational Constant and the Length of Day;
    Europhysics Letters, Volume 110, Number 1

    3) Zhu et al – Testing Theories of Gravitation Using 21-Year Timing of Pulsar Binary J1713+0747; arXiv:1504.00662v2 (Draft 2015/08/20)

    Note – With the growing number of broken links on the interwebs, I prefer to provide key search words that should always lead to the appropriate source – I will attempt to do this more often in future – there’s so much great science out there!

    Mo shùile togam suas (Gaelic – I will lift up mine eyes)

    Post Script – I cannot believe I missed this! How long have we been kicking this around? Let’s touch on the temperature scale issue one last time. We will call on blacksmiths to assist … take a cold piece of iron bar stock and place it in a blast furnace. Before it starts to heat, the iron rod is BLACK. As it absorbs heat, it goes through a series of colour transitions – first dark red, then dark orange, progressing through to bright orange, and finally, when the rod is at its hottest … it turns WHITE hot. There’s your “black-orange-white” scale presented in the simplest and most concrete manner possible. You will also note, that each colour represents a REAL temperature (not some made up, off-scale “infinite” EU “my comet is burning” temperature).

    You will also be pleased to know that at the AGU 2015 Conference, the VIRTIS team will be giving an update on measured surface temperatures! As stated in the presentation abstract, between rendezvous and April 2015, maximum surface temperatures have not exceeded 300 K!

    Part 3 is coming …

    • originalJohn says:

      Booth, you are certainly not going to get as lengthy a reply from me on this partly because , unlike you I am not going to make it a patronoising and presumptive lecture which drifts way off the point under discussion.

      I am going to give you some punchy bullet points to chew on ( or misinterpret) as you wish.

      * the electric universe paradigm is far from a house of cards, even though you want it to be, to avoid the embarassment of deluded devotion to the baseless ice comet story (and more)

      * in any event the eu paradigm does not rest on the mass anomaly.

      * the assigned densities of the gas giant planets are also anomalous and calculation of them depends on a constant G. Similar considerations could apply about charge state and effective mass.

      * I am well aware of the densities of comets, asteroids and planets ( and incidently also meteorites which we can actually pick up and measure). I have no dispute with the values of measured density of comets, or I should say the comet because 67P is the only one actually measured as I understand. With all other comets the density is calculated from an assumed mass based on the good old comet model and estimated volume.

      * I do dispute that the measured density can be directly comparable to densities measured on other bodies ie Earth. Therefore low density does not necessarily represent high porosity.

      * according to the charge theory of mass the difference in density between comets and asteroids is perfectly acceptable. And I have elsewhere predicted by the way that change in charge state of the comet would change its mass. You seem to have missed that.

      * so let us get it clear. I do not claim and I am sure the eu paradigm does not imply that the density of 67P was incorrectly measured or is wrong. You have misconstrued that.

      * the four gravity assists worked because we can be reasonably confident of the mass of Earth and Mars. It does not PROVE anything about the solar system in general. And best not to mention the Moon.

      * integral calculus is not science it is a language as are juicy physics calculations and I am no more impressed by them than by any means of descriptive communication, unlike you apparently.

      * all of the laws of physics work in the electric universe. They do not however in your consensus universe. Dark matter, netron stars, black holes, the big bang etc etc.

      * I am obviosly in no position to gather comet evidence data. Only Rosetta can do that for now. I rely also on evidence gathered by NASA in the last 20 years or so that the solar system is laced with electric currents. Find it for yourself with an appropriate search.

      * with regard to G you say ” It’s (sic) experimental determination does, however, appear to be impacted by some variability associated with the Earth’s structure and composition! An exciting mystery to a scientist!!! ”
      Agreed except I would say structure, composition and state of charge and that is close to what I am talking about.

      * KOSI, This bullet may be a bit longer. You seem to rely on KOSI in your argument. Why ? KOSI was built around a model. A model derived from the sublimation hypothesis. Measurements were made on the model. Neither I nor anybody else I am sure would argue that the ice sublimation effect was not possible. I most definitely would however argue that there is no evidence it is happening with comets. Measurements on a model do nothing to change that. In other words no doubt sublimation of ice could occur, with cometry densities. Does it occur ? None the wiser. The Roseetta resource is is in a different league however and could provide the answers.

      * Your conclusion on density is wrong. The electric comet model does not care what the comet is made of including ices, It relates to what the discharge is and how and why it happens. The highlighting of the density anomaly is a factual obsevation. The standard model requires a porosity measurment and that has yet to be achieved. It is very important because it could verify the constancy of G or otherwise.
      By the way ESA recently published a figure for the comet jet emission content of 😯 % dust 20 % water. And incidentally I notice also published a paper in which it was admitted that the force exerted by sublimated gas was an order of magnitude insufficient to overcome the fracture strength of rock and separate dust particles from solid material. And there is an interesting point. Why don’t the Rosetta team collect and analyse the comet dust emissions and reasonably conclude from that what it is made of, as NASA did with the Stardust mission to Wild 2.
      They have had far greater opportunity than the Stardust mission did.

      * somewhere also in your piece you assert that the comet nucleus and all other bodies up to stars are made up of individual point masses held together by gravity. This is of course wrong. Let us say the point masses are atoms or ions. Then in solids they are held together by the bonding forces between atoms. In plasma by the electrical and magnetic forces within the plasma, which incidentally are at least a billion billion billion times stronger than gravity.
      And let us be clear that the gravitational accretion theory for comets is a hypothesis as is the nebular accretion theory for the solar system ( a hypothesis without a plausible mechanism in fact).

      * temperature scale. From what you said in your PS I wonder if you read my last reply beacause you did not answer my question relating to the Sun.
      You talk about the optical emissions of a hot iron bar. You would not place it in a blast furnace Booth, that is a specific iron extracation construction . But there are similarities to the blacksmiths coke hearth which is also pumped with air to increase the heat intensity so I understand your choice of that terminology.
      Jumping to the point white hot is called white but it is not actually white but emits other colours including blue. And neither does it represent a specific temperature.
      White hot denotes a paticular threshold temperature and all temperatures above that threshold would be denoted white hot also, though they would have different spectral emissions. ie they would be diffrent colours. In fact it is the mixture of emission wavelengths which makes the colour approximate to white. So molten iron in an actual blast furnace tapping flow could reasonably be described as white hot and molten steel in a melting shop although at a lower temperature would also be called white hot. And the slag on the steel which is tapped off first is also white hot but a bright white hot as it is 2 or 300 deg C hotter than the sreel. And finally a welding arc would be described as white hot ( though distinctly bluer) at a temprature of 5000 deg C plus. So my point stands. White on a colour scale does not represent a specific temperature but a notional threshold.
      White on the VIRTIS camera scale represents a chosen threshold. It is an artificial colour not an actual colour as in the above examples. Unlike the above examples it does not change with higher temperatures. So in the imaging camera 230 deg K white, 2000 deg K white.

      * that’s it for now Booth. I would however like to emphasise that I do not represent the eu paradigm. I have however learned a lot from those that do represent the eu. It is like any other aspect of knowledge. You are exposed to it, you research it and you draw your conclusions. My conclusion as you will have gathered is very strongly in favour of the eu paradigm and against many of the consensus theories of astro physics and cosmology. But I speak as an individual.
      You seem perplexed by how a large majority consensus in science could be wrong. I could explain how to you but unfortunately it is outside our scope here. I remind you though it has happened on many occasions in science history.

      • originalJohn says:

        Booth, “80 % dust to 20 % water” obviously not 00 % dust as above.

  • sjastro says:

    Capcha issues.

    Originaljohn wrote,
    “Much as you would like me to be, sjastro, I am not an evangelist and I do not represent what you call the EC either. Such assertions are ploys commonly used by your category of person, the consensus believer, when you have no other argument. I am simply considering the facts and the evidence and judging the most likely explanation. I have no desire to convert you. On this blog i am presenting a case to the open minded and perceptive for not believing the hackneyed standard model of comets, for which there is no evidence, and for looking for other explanations. A great deal of evidence for the electrical nature of the interplanetary medium has ensued in the late 20th and early 21st centuries, from NASA sources. Find it if you are interested. Not magic, or belief but observational evidence. People like you object to it because it questions some of their sacrosanct beliefs and the pronouncements of some of their heroes, so they ignore it and pretend that the consensus is the truth. The consensus is being challenged my friend. It is a quest for a true understanding of reality. if you are not interested in that it does not concern me. Stick to the old faith story if you wish but let the truly objective and open minded draw their own conclusions. The consensus of science has been collectively wrong many times in the past and unfortunately with regard to comets and cosmology it looks as though it is too in our era and you appear to be a voluntary victim of the ignorance.”

    Originaljohn,

    The question of the so called lack of mainstream evidence as opposed to your own version of evidence has already been addressed here.

    http://blogs.esa.int/rosetta/2015/09/23/rosetta-reveals-comets-water-ice-cycle/#comment-572943

    Along with your logical fallacies highlighted in that post, I can now include two further characteristics based on your latest response.
    First of all accusing me and anyone else who disagrees with you as being motivated by faith when in reality your “hypothesis” is nothing more than a faith based opinion, is an example of projection at work.
    https://en.wikipedia.org/wiki/Psychological_projection

    Secondly your commentary based on self grandiosity wanting to deal only with the open minded who are receptive to your profound ideas, despite you having very little understanding of basic science, is an example of the Dunning Kruger effect.
    https://en.wikipedia.org/wiki/Dunning-Kruger_effect

    What is quite laughable is that the “open minded” are those that are expected to blindly accept your ideas. Those of us who question it and point out the flaws, will automatically be characterized as mainstream zealots protecting their religion.

    It’s painfully obvious you are incapable of discussing the science and therefore rely on diversionary tactics.
    For example a relatively simple question was requesting the source to your claim that G has a large physical variation. Instead we get this irrelevant diatribe.

    Your inability to provide an answer is because your claim is pure bogus, as is the assertion that mainstream science is lacking the evidence.
    To top it off the evidence purporting to support your own hypothesis is bogus as well as you have never supplied A SINGLE LINE OF SUPPORTING EVIDENCE.
    It is entirely based on false dichotomies.

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