Updates from AGU

Yesterday, 17 December, there was a special session dedicated to Rosetta at the 2014 autumn meeting of the American Geophysical Union (AGU) in San Francisco.

Many scientists from the Rosetta and Philae instrument teams reported on their latest results. To kick the Rosetta day off, some of the results were also presented in a press conference featuring Matt Taylor, ESA Rosetta Project Scientist, Claudia Alexander, US Rosetta Project Scientist at NASA, Kathrin Altwegg, ROSINA Principal Investigator at the University of Bern, Switzerland and Jean-Pierre Bibring, Lead Lander Scientist at the Institut d’Astrophysique Spatiale, Orsay, France.

Matt Taylor introduced the past, exciting year of Rosetta leading to the comet landing on 12 November, and Claudia Alexander summarised what we know about comets so far and the science goals of the mission. Then Kathrin Altwegg talked about the status of the ROSINA instruments and the recent result on the measurement of the isotopic composition of water vapour coming from Comet 67P/C-G. Finally, Jean-Pierre Bibring summarised the landing of Philae, the scientific experiments that were performed during descent and on the comet’s surface, and possible future plans in the case that the lander will wake up.

You can watch a replay of the press conference here:

Posted below are some of the images presented during the press conference: the first blurred CIVA image, taken shortly after Philae’s first bounce, a reprocessed version of one of the frames in the panorama taken by CIVA at Philae’s final resting place, showing the so-called “Perihelion Cliff”, and an illustration showing the lander’s likely position on the comet’s surface.


Philae’s blurred view during its first bounce on 12 November 2014. Credits: ESA/Rosetta/Philae/CIVA


Philae’s view of “Perihelion Cliff” at its final resting place on the comet’s surface. Credits: ESA/Rosetta/Philae/CIVA


The likely position of Philae in a visualisation of a topographic modeling of the comet’s surface. Credits: ESA/Rosetta/Philae/CNES/FD

You can also view a replay of some presentations from the science sessions on the Virtual Options environment of the AGU website. (You will need to register to view the videos, but registration is free.)



  • Robin Sherman says:

    Having seen all the presentations that were actually shown, four are still not viewable and one was cancelled, I thought I would outline the key things that were common conclusions. A lot of results just defined boundaries or the range of results and some did not match existing models or experimental data closely enough to give exact conclusions. The majority of the Philae reports amounted to a list of what data was collected and how they might be able to use it.

    The Northern “Duckiesphere” currently in Summer is way more active than the “Dark Side”. The detection of metal ions like Sodium, Magnesium, Zinc, Iron is limited to nighttime observations and is thought to be due to sputtering from the Solar Wind and Cosmic Rays. They are not seen during the day, because cometary activity produces a coma containing gas, ions, charged particles and dust that physically and magnetically shields the surface from the Solar Wind.

    Activity is directly correlated to the amount of sunlight incident on a surface, but the neck areas and the north polar plain are more active than the head and body lobes due to a thinner layer of insulation. These more active areas contain fewer organics. The majority of the surface layer away from the active regions contains between 5 and 7% organic material, with the highest amounts on the sides of the lobes where there is a lot more exposed solid material. The nature of the organics is still not known, one fit to the data suggests a mixture of a neutral black material with 99.5% Tholins and 0.5% Water. Another result suggests that it is not all Tholins and is likely a mixture of Carbon, Tholins, Low Iron content silicate minerals and various Sulphides.

    The consensus seems to be that in the flatter plains where the surface appears to be covered in a dust blanket, like at the first touchdown point, there is a top ice free layer of friable, porous, gravel and dust about 1cm thick made up of low iron minerals, silicates, organics and Carbon. Below that the material starts to contain volatile ices, the amount increasing with depth. This mixed ice/dust/organics layer varies, but is estimated to be 10 to 20cm normally, but may vary. Beneath this is a hard layer of sintered ice/dust/organics, which although hard is also brittle as evidenced by the shards seen in the ROLIS images.

    Sulphur is present in significant amounts and is usually found in the areas where Water is coming from, but also from a few areas where very little Water is seen. Although visually the comet is pretty homogeneous, chemically it seems not. Water tends to be produced in very variable amounts related to the time of day and position on the comet, whereas Carbon Dioxide emission seems to be more constant. The ratio of CO2/H2O is on average about 7%. The thermal properties of the top dust layer suggest up until now outgassing is not coming from the harder sub surface layer.

    The CONSERT talk was limited and the second one cancelled, presumably because Philae has not been located. The data is clear and of good quality, but the only conclusion is that the shape of the signal peak indicates very little or no scattering from internal surfaces, meaning the comet is not currently made up of metre or two sized planetesimals, but is a continuous solid.

    Organics that have been identified include C2, C3, C4 compounds and Benzene. Other results indicate Amines, Benzoic Acids, Ketones and Esters are probably present as well. Dust particles from the comet are larger than expected, but are very irregular, conglomerates of very loosely bound material which falls apart on contact. More solid grains have been examined which although only micron size look like mini comets, with planes, pits and holes. They have also been seen to move once trapped in the instrument. This was explained as being their light weight, but sublimating gas creating a frictionless layer underneath them likely helps.

    The surface layer at Agilkia was revealed in all it glory by the ROLIS images. Hopefully those images will be available here soon. This was the most informative and revealing presentation shown. Analysis was done of the particle sizes and the surface seems to be made of a sort of pea gravel 1 or 2 cm in size with larger pieces of broken cryorock mixed in. Hollows and depressions around a metre in size along with small ledges and elevation changes in the 10s of cm range. Little tiny landslides of little pebbles, but little sign of dust except at the base of the 5m Cryobolder close to the touchdown point. It would appear that the surface layer material is very much like a type of aerogel, it holds it shape perfectly until disturbed and then just disintegrates into a fine powder. This is what was seen in both MIDAS and COSIMA. Unfortunately the dust measuring device on Philae has so far only registered 1 confirmed hit.

    The team seem even more confident that Philae will survive and be able to do more science. It is clear from these presentations that there is lots of revealing data available, there are vast amounts of it and much of it requires some new algorithms and models to interpret, especially the Philae data. An amazing job by everyone involved. I should also add that the speakers were way more entertaining and interesting than many of the others here.

    So most of what we learned in the presentations that were shown, had already been deduced by ourselves or explained by team members here and this just added confirmation that many peoples combined educated guesses were right. The talks showing OSIRIS data and explanations of the comet morphology were not streamed and information from the plasma and magnetic field experiments were not shown. Hopefully some sort of apology or explanation from the ESA team will be forthcoming to explain this.

    • Stu says:

      ESA has no need to apologise for the continuing lack of OSIRIS image, because they have no influence over the release of OSIRIS images, or over the team itself. The OSIRIS team is essentially – or at least sees itself as – running a totally different space mission, independant from ROSETTA. Having hitched a ride to the comet onboard a spacecraft funded by the public and the countries of Europe, the OSIRIS team now feels no obligation to, and has absolutely no interest At All in, sharing its images with the media or the world at large. This is disgraceful and after ESA has made such HUGE strides in recent years re Outreach and media relations, having successfully shaken off the old image of a space agency which is very poor at Outreach, the OSIRIS team, with its selfish and arrogant image hording, is now damaging ESA’s public image. To say they are “protecting their science” by not publishing images, and then to show those images to halls packed to bursting point with fellow scientists, many of them rivals, shows just what contempt they have for the space enthusiast community and the public at large. One can only hope that future ESA missions insist that the science teams,. and their PIs, are, under their contracts, obliged to share their results more generously, because this situation is just not acceptable. The OSIRIS team told us they would be releasing an image a week, which everyone agreed was pathetic, but better than nothing. As it is, we’ve had one image from the OSIRIS team since landing day. They are laughing at us, plain and simple. Well, that’s up to them, but in years to come they will be judged very harshly for their actions, and I can only hope that when it comes to the ROSETTA mission requesting funds for a mission extension the refusal of the OSIRIS team to engage with the media and the public will not go against the mission as a whole.

      • Robin Sherman says:

        Hi Stu. Thanks. I wanted to say all that, but my post was already getting too long. Well said.

    • Dave says:

      Nice summary Robin,

      Very dissapointing we did not get some preliminary OSIRIS stream, and not showing any plasma and electric field measurement, just seems incredulous, especially as some of the experiments fired up some time ago. It would of been good to know nothing much unussual is happening or something unusual is happening but we need time to analyses.

      There seems more information on siding spring from instuments not intended to measure the close pass, but the information is still sparse(more understandable though)

    • Haerwe says:

      Robin, I am impressed by your expertise !

      On the tenth of October (14) I presented on this blog my view why a landing attempt at ‘J’ will result in a CRASH

      The reaction of the Blog editor here: she put me ‘under moderation’

      Robin, seeking science information – this is not the right blog – serious

      I also placed the question here whether we have to expect the same info policy on DLR/Philae as seen from OSIRIS

      Well, guess yourself

    • Denis says:

      Thanks for the overall summary!

      As for your last sentence, I don’t normally defend ESA, but in this case, I don’t see what ESA has to do with this issue. The scientists who did the presentations (and chose to have them streamed or not) are not affiliated to ESA in any way.

      Here is an interesting article about the data release issue, which basically says that (some of) ESA’s management agree that not enough data (OSIRIS pictures in particular) are being relased and that people at ESA have actually no more direct access to these data than you or me.
      One problem is that ESA, has no way to put pressure to release more data because the instruments are not paid by ESA (contrarily to NASA for example).

    • Kasuha says:

      I am almost certain that Osiris images are held back to allow the Rosetta team to draw scientific conclusions from them before the public does. Since ESA is paying for the mission, they have right to have first access to science and scientific credit that can be drawn from it. I believe all Osiris images will be released to public at some later date.

    • logan says:

      Hi Robin. “..More solid grains have been examined which although only micron size look like mini comets, with planes, pits and holes. They have also been seen to move once trapped in the instrument.”

      Core particles, I guess.

  • Sovereign Slave says:

    So much for objective science reporting. Simply unbelievable. First we get the “this is how the solar system formed” theory/propaganda presented as fact from Claudia, and then each presenter pretty much references the same old unquestioned theories as the reference points for the data they present, basically shaping the data to fit the theory. I think Catherine summed up this ridiculously biased approach at minute 55 – after saying P67 is for sure a real Kuiper Belt comet, she then goes on to say that”I’m quite the long time in this business. I started out with Shatow (sp?), and it’s all this changing. Before Shatow we only had Oort Cloud comets. Then we invented the second reservoir, the Kuiper Belt. Then they started to mix, and today I think we have a big mixture of everything in everything.” At least I’m not the only one confused.

    So instead of showcasing real science, they showcased how you play fast and loose with data as fuel for speculation in support of bias. And with this approach, the data will always say whatever they want it to say.

    • Robin Sherman says:

      I’m not sure where in this post Claudia espoused this “propaganda” or what facts she stated other than a presentation was made by the Rosetta team.

      Understanding and the elucidation of mechanisms and processes in science is and always has been a process of evolution and revision in the light of new facts. This is the history of science. If you can’t reconcile the new data to the existing models and theories then the models and theories need revision. At this early stage of the analysis of the Rosetta data the team have just started that process by trying to explain their data in terms of the current widely accepted theories and experimental models. It is clear that some data does not fit very well to these, so they will need to either be rejected or modified and other theories and models looked at.

      In order for those theories to be used to test their data, they first need to have theoretical mechanisms and testable quantitative predictions. If EU theory had any of the relevant mathematical proofs, numerical models, experimental models, cross references to other physics mechanisms and testable outcomes from them, then perhaps the Rosetta data set could be compared to them, but since it doesn’t the team can’t. If you want certainty and black and white conclusions, then either wait twenty years or believe a simplistic faith based theory that dictates only one pre determined answer.

      • Sovereign Slave says:

        My comments have nothing to do with EU theory, it has to do with methodology. As I posted once before, this quote pretty well sums it up:

        “It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.”
        ― Arthur Conan Doyle, Sherlock Holmes

        The Rosetta team now has a huge amount of fresh, up close, never-before-acquired data about a comet. But instead of starting fresh and using the data to build a step-by-step, fact based model of comets, they’re filtering the data through theories about comets that were formed with much much much less data. When you point out that “If you can’t reconcile the new data to the existing models and theories then the models and theories need revision,” you highlight the flaw in their methodology. There’s a very strong inherent, biased tendency TO reconcile the data to the theory you believe, especially if you are heavily vested in that theory, which these scientists very obviously are. And yes, EU scientists do it as well, and developing models is necessary, but few seem to even acknowledge this danger in methodology.

        Oh, and Claudia’s bit was at the very beginning.

        • Robin Sherman says:

          Apologies SovereignSlave for the confusion of Claudias. I thought you were referring to Claudia’s post above. Having watched the press conference again, I realise you meant the Claudia from NASA. To be fair she did point out that the model she used was one of several, none of which matched observations, including the one she used. Its pretty difficult to talk believably about uncertain conclusions from a model you know to be speculative and inaccurate. In her defence though no one knows the whole solar system evolution scenario yet, so she is forced to pick what in her opinion, is the best guess. I do understand your point about the uniqueness of the data, however 67P is not on an island in terms of planetary science and its properties and mechanisms need to be related to existing knowledge and understanding from other solar system bodies.

          The other issue you raise, which I also understand to some extent, is the need to do things in the manner others have done before for it to be credible in terms of peer review. There are pros and cons to this methodology. I agree, it stifles radical thinking, but ensures continuity and mitigates some of the natural human antipathy towards change. Its a basic fact of modern science that if you hope to get your ideas accepted, you had better be able to “show your working” to use the old exam phrase. Such is the breadth, depth and interconnectivity of all aspects of scientific knowledge these days, there is no other option. If you put forward a theory, there are thousands of research scientists around the world in hundreds of different specialisations, who think and probably can pick it apart, or more likely point to some proven published article that does so and the majority would take great pleasure in doing so. A single scientist or team of scientists can only hope to add one minute piece to the vast jigsaw puzzle that is modern science by proving that piece is the right shape to fit all the myriad others around it.

          Having watched a number of the other papers on Earth Sciences, Climatology etc. about 70% of each talk is about showing your methodology is consistent with other peoples so that results can be compared and your conclusions are valid. There are standard ways of measuring data to ensure statistical and calibrational accuracy and this invariably relies on quoting and using established methods and models. Its pedantic and time consuming, but at least it ensures rigour. Scientists and observers of science, such as ourselves, are by profession, nature and deed, very sceptical.

          The way things are looking, apart from what is already known about what comets are made of, they are finding that they are pretty well starting from scratch. I also get the impression that a number of the science team members are revelling in that fact. The AGU meeting to a large extent was about showing that the Rosetta and Philae data, was of the highest quality and obtained in an unimpeachable manner. Theories and conclusions, processes and mechanisms, were very thin on the ground from the instrument scientists. Unlike Claudia from NASA, Matt Taylor stuck to known past and future events and didn’t get into the mess that she did.

          • Sovereign Slave says:

            Well, my last reply to you Robin of course got me going even more, so here’s to beating a dead horse just a bit more.

            I think most would agree that the science is only as good as the question or questions which the science is seeking to answer. In my opinion, for a vast number of obvious reasons, focusing on seeking to answer the question “What is it right now?” is a much better question than trying to answer “What was it in the past.” But we have a situation in cosmology where for many decades the focus and activity has been on answering questions about “what was it,” then taking stacked upon stacked theoretical answers to that question and using it to interpret “what is it.” Just imagine what cosmology would be if you completely took out the questions, “Where did it come from and how did it form.” How much of cosmology would be left? How many theories? Not much, and not many. What’s left should be the bedrock, but instead all the other stuff is. It’s an upside-down pyramid, a relatively small amount of scientifically verified data used and interpreted in such a way as to support a vast amount of purely speculative theory.

          • Sovereign Slave says:

            Hi Robin, I’d posted one post before the 21/12/2014 at 21:15, but it apparently got censored as it hasn’t appeared, but it included a huge hats off to you for your excellent summary, which I also appreciated, just wanted to let you know.

          • THOMAS says:

            Sure, Sovereign Slave.

            But you must admit that the whole process is humanly comprehensible, given that the most eminent scientists out their have decades of work behind them which they understandably defend, whatever the new findings may be. Why should scientists be less human than the representatives of any other profession? Conservatism rules everywhere, for obvious reasons.

      • Harvey says:

        Exactly – & thanks very much for the summary.
        Whilst in general terms I would defend the team’s right to first cut at he data, in this case I do think the OSIRIS team are getting it wrong & being overly parsimonious with releases.

        Regarding models to examine, this paper, the references it cites, & the papers that cite it are an interesting, rather detailed look at how a porous icy body might ablate etc. Invitably of course its built on a tower of assumptions, but interesting to view Rosetta data with it in mind.

        Planetary and Space Science 50 (2002) 983 – 1024
        An advanced physical model of cometary activity
        A.V. Rodionova, J.-F. Crifob;∗, K. Szeg˝oc, J. Lagerrosd, M. Fullee

    • shatow? says:

      She speaks about the Giotto mission, which did a flyby of the Halley comet (1986?).

  • Steve Kasian says:

    Can someone please tell me why one of the images from the presentation (the one looking down, across, and into the “canyon” below) is missing from the story, and apparently from the website? Also, if you could please also post a link to the full quality version of the image, it would be greatly appreciated.

  • Herobrine says:

    I spent a good part of the day trying to deconvolve the CIVA image that was released, to reverse the motion blurring and see if there was anything recognizable in it. I generated deconvolutions for different angles and blur lengths. http://i.imgur.com/5XO8Q3z.gif
    I combined them based on the apparent angle and length of the motion blur across different parts of the image.
    Here’s the original:
    And here’s the result:

    Deconvolution of motion blur is a tricky thing to do. To get an accurate result, you really need to know details of the nature of the motion. I can’t tell you how accurate this result is. It’s likely the result in this instance bears little resemblance to what was actually in frame. On the other hand, maybe I got lucky. Either way, I can’t really identify anything in the result image. I see some things in it that I could possibly associate with certain features near the initial touchdown location, but I could just as easily associate them with various clumps of soil in my garden.
    So, take this “deconvolved” image for what it’s worth, which is not much. Bad deconvolution can still often give the appearance of having reasonable features even when the result is garbage.

    Maybe if the team released the raw image data, which I’ll go ahead and assume to be 16-bit lossless image data, like a FITS file or something, which contains quite a lot more data than these JPEG images they’ve been releasing, then it might be possible to take another shot at deconvolving it, taking advantage of better data for the deconvolution and better data for trying to identify the blur angle and blur distance. Would certainly help if I could track down any calibration data for CIVA that would point to its point spread function.

    • logan says:

      Thank a lot for taking the time, Herobrine. Structure remembers me of corals. First commented by Jacob?
      Taking CONCERT data with your same salvos.

  • Cometstalker says:

    A lot of words for not much to say. Its time for the audience to hibernate until July 2015. God Jul, happy new year und frohe Ostern.

  • Kasuha says:

    Thank you for the video, and thank you for the link to the AGU site, those extra presentations were definitely worth the registration.

  • Daniel says:

    Quite a while ago I made an animation on how the touchdown location changed using the images released. Of course that’s old news now, but I’m sure it can still be of interest. Fits in anyway seeing as they talked quite a about Philae,
    The gif starts with the before touchdown images from ROLIS and OSIRIS, then continues with the post-touchdown image from OSIRIS. Then an attempt to circle what seemingly changed (roughly). Finishing of with a crude addition of the post-touchdown image from NAVCAM, which I haven’t bothered to align that well due to the low resolution. Regardless it does show how the origins of the dust cloud shadows (I guess?) on the NAVCAM image lines up quite well with the what changed on the OSIRIS images.

    • Robin Sherman says:

      Really good stuff Daniel. There are more ROLIS images taken from as close as 9m altitude before touchdown, which hopefully will be available soon, which would be nice to add to this.

      • Daniel says:

        Thanks. I also hope that we will get the other ROLIS images, but I can live with waiting a while longer. I’m also looking forward to, eventually, seeing any new OSIRIS images of the first touchdown point to see if it has changed a whole lot since, you’d imagine that such a “disruption” could lead to relatively quick changes. Hopefully a reconstruction of the bounces/landing will be done and presented as well.

        Thank you for the summary of the AGU presentations by the way.

  • logan says:

    Want to thank you Claudia and Robin about updating us about the news at AGU 🙂

    • Robin Sherman says:

      Thanks Logan. Unfortunately I have been afflicted with a dreadful cold/flu bug this week and can do little else, but scour the web for Rosetta info. Thanks to those above who appreciated the overview too.

  • Graham Hall says:

    A great précis of the Rosetta presentation.

    However in one of the other 15 minute presentations it was said that the jets of material are leaving 67P at a speed of circa 700metres per second. That doesn’t sound much like sublimation to me – dry ice sublimating on a stage doesn’t jet away from the source- it floats away in whisps – does earths gravity really have that much effect? 700 metres per second sounds akin to explosive to me. Why isn’t the surface dust more disturbed by this departing material – is it just that the image resolution is still to low to capture it, or the dispersed nature of the emissions still too low – are we having to wait a few months for the mechanisms to become more dramatic?

    • THOMAS says:

      @ Graham Hall

      “in one of the other 15 minute presentations it was said that the jets of material are leaving 67P at a speed of circa 700 metres per second.”

      Thanks for this interesting tit-bit! Which presentation was it, do you know?

      In any case, the energy source for such velocity clearly cannot be kinetic or thermal, it is necessarily electromagnetic. The EU model has emerged vastly reinforced from this update session, on several counts…

      As for the non release of the huge OSIRIS datasets, I personally surmise that the detailed observations are so totally contrary to mainstream expectations that they are literally unspeakable and unshowable at the present time. Once finally released, I am confident they will turn out to be absolute dynamite.

      • Harvey says:

        Out of idle interest, what electrical mechanism is accelerating neutral species?
        Rockets, which seem remarkably ‘kinetic/thermal’, routinely achieve exhaust velocities of a few km/sec, & any small hole in a high pressure pipe will achieve sonic, ~450m/sec for a natural gas pipeline, ~1300m/s for hydrogen, fastest of course.

    • Harvey says:

      It wont look anything like ‘sublimation on stage’ because its expanding into hard vacuum.
      If there is any sort of reservoir below, with an exit through an aperture of some sort, its likely that ‘choked flow’ will result. A shock wave forms in the exit aperture, & the gas exits at sonic speed, ~~~400m/sec in water vapour, so the right order of magnitude for thie 700m/s. As far as I can see the formation of choked flow depends on the pressure *ratio* upstream/downstream; the downstream pressure is so low even very low upstream pressures will still cause it to choke (provided mean free paths remain short compared to the aperture size I guess) – but can anyone knowing more fluid dynamics confirm that?
      Again I would not expect the dust to be much perturbed, because very close by the pressure will fall to such low values it wont exert much force on the dust.
      Even in the putative reservoir, the pressure is low, constrained by the vapour pressures of the mterials & available heat flux to sublime them, maybe less than 100Pa? Depends on the temperature & material mix. On earth that is ‘rough vacuum’, & things dont get pushed around.

      • Marco says:

        Hi Harvey,
        The fluid dynamics there is about right, and there was some peer reviewed science linked from a comment somewhere which went into that. The main issue with sublimation being the driver, however, is the energy transfer models to sublimate below the surface in a chamber and through a nozzle and taking dust particles with it. It is too contrived to be “expected”
        By the way, did you have a look for yourself regarding A Cooper’s forensic photogrammetry demonstrating a match between head and body. The science is quite well developed, and accessible somewhat to us “citizen scientists” it is about working out 3D shapes from (navcam) photographs, and calculating distance and relative direction between surface points, then falsifying or verifying distance and direction on the opposite lobe.

        • Prof Harvey Rutt says:

          I looked into the choked flow issue further. It would appear quite possible this will happen. For a ‘thin plate’ aperture the flow never really chokes, but it does not appear to require anything resembling what one might call a ‘nozzle’ to get real choked flow, just a very short passage. Th e MFP condition is easily met. However if the mass flow rate from the subliming walls of the ‘reservoir’ is less than the flow rate defined by the aperture and sonic velocity, the flow won’t choke.

          What I would need in the ‘image matching’ is some statistically valid test that it is not chance. there is a certain structural similarity of scale and type of feature; so it might be rather easy to ascribe ‘matches’ to chance similar features. The eye is very good at finding what it wants to see!

          The ‘stretch’ mechanism seems implausible to me for four reasons.
          Firstly the forces are *extremely* small; they wouldn’t strech wet tissue paper basically; I struggle to believe it’s that weak.
          Secondly the mechanism seems inherently stable if you stretch a body having a given initial angular momentum. Yes, gas jets etc can alter it, but it would take *vastly* bigger spin ups than those observed.
          Thirdly, you get ‘matching features’ most easily across a brittle fracture. But that would surely have lead to rupture and two bits. I struggle to envisage a stretching process which leaves it intact, but with matching features.
          Finally, timescale. How long would such features be preserved given surface remodelling near perihelion?
          Not many orbits surely. How credible is it we keep bumping into comets very shortly after the got stretched. Several have had this shape.
          We don’t yet know; but stretching looks unlikely to me.

  • Thanks a lot to Robin for the very good AGU 2014 summary!
    But I have to underline again the absurd behavior of OSIRIS team that asked to delete the streaming of the OSIRIS presentation. To be precise, in the section P32B devoted to Rosetta mission, only the OSIRIS presentation (P32B-02) was eliminated ! An incredible decision that damage above all the OSIRIS team. Evidently some big problem arised to the OSIRIS camera and they decided to hid this information to the public. But even if the OSIRIS picures exist and, as promised, they will be release after six months, no interest will be remained in the public at that time. As a consequence, the founding of a camera as ROSETTA will be more difficult in the next future, possibly never more allowed.

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