This NAVCAM mosaic comprises four individual images taken on 4 November from a distance of 31.8 km from the centre of Comet 67P/C-G. The image resolution is 2.7 m/pixel, so each original 1024 x 1024 pixel frame measured 2.8 km across. The mosaic has been slightly rotated and cropped, and measures roughly 4.6 x 3.8 km.
Four image NAVCAM mosaic comprising images taken on 4 November. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
This mosaic was relatively tricky to make, given the lack of features in some of the overlap regions and some rotation of the comet between images. But as always, the individual images have also been made available below to allow you to check on the accuracy of the mosaicing.
The larger lobe of the comet is seen in the foreground and the smaller lobe behind (Note: the original post had this the wrong way round, sorry!). As with the OSIRIS image posted yesterday, we are looking into deep shadows on the small lobe, below the ‘neck’ of the comet. However, the brightly sunlit parts of the comet reflect enough light into the shadows to reveal hints of the features there, with the help of some image processing to bring out the full dynamic range.
Emission from gases escaping from the nucleus of 67P/C-G is also visible on the right side of the image, although it is not immediately obvious in this picture where the source of the emission is. Finally, there are many small white blobs in the image which could well be real objects in the vicinity of the comet rather than cosmic ray events hitting the detector.
Discussion: 120 comments
That seems to be the collimation hitting the ‘chin’ of 67P.
Very useful dynamic range work. Thanks Claudia and H. NAVCAM team. Don’t think it has any pass filters.
Is ‘particle-sphere’ about to become ‘nebular’?
Please Gerald. Do the ‘particle’ magic.
Will the landing be transmitted live?
This picture surely puts a stop to contact binery theories. The neck is being eroded, so making the neck ever smaller. Also the collimated jet is also cutting into the head leaving Striations that we have seen clearly in other photos.
Also this looks electrically driven, too concentrated for a sublimation effect. The reasons for the erosion at the neck have been described on several previous posts. Also the resulting characteristic shape has been demonstrated in laboratory and also been described on previous blogs
Agree, Dave. As of now doesn’t look like a binary.
Just how cold is this comet and when will it split in two?
How long does the lander plan to be on the comet? If there are ice jets that suggests water? Could they be ice jets?
The plan is that the lander will stay put on the comet for the next 10000000 years until the space archeologists pick it up again and try to analyze what kind of species wasted a lot of money to put som junk on such a worthless piece of rubble pile.
‘Money’ is a power to whoever to do whatever they please. Sound ‘smart’, doesn’t it?
More interesting is if there are any plans of what to do with the orbiter once it has fulfilled its purpose. Will it just be left at random orbit or will a landing approach be made? I would recommend a 100 or so kilometer orbit and dormant period setting the wakeup alarm-clock to the next close encounter with earth.
Hi Tammy. The instruments say there is water. They ‘smell’ it, but not that much is seen on the surface.
The Philae lander was designed as a no-return mission. The plan is for he to do science as long as he can withstand the ‘heat’.
Its about 200 kelvin getting slightly warmer and it will split in two about ten minutes past twelve, plus minus a day or two.
Ice sublimating on the surface would leave its source in a more or less hemispherical pattern. Ice sublimating below a relatively thick porous structure will be focused in a manner that makes constituents ( gas, dust) leave the surface in a more or less perpendicular direction. In previous photos we have seen beams with each their own orientation. How would that fit with a forcefield? The way the porous layer focuses the beam corresponds to the nozzle of a jet engine: even though the structure differs the pressure phenomena are similar. Same phenomenon as in acoustical horns.
Wrote jet engine ment rocket engine.
What you are saying is that the comet had its own attitude control thrusters…… I am thinking it is going for a bad attitude.
🙂 not really. Collimation is not expected from a source sublimating at the surface, but the exit through a porous layer may under certain conditions act as a collimator.
Thanks for filling in for Emily, Claudia. Back to 30Km orbit, but there is still considerable evidence of sublimation related activity to be seen. This is an unfamiliar view almost looking along the equator at what might be called the Eastern Hemisphere. The flat areas on both lobes are noticeable for their sparse covering of “Reglisse”. It has almost been eroded down to the subsurface layer. Again there is the impression that these two areas were once joined and part of a continuous feature. This area has seen more solar radiation than the Northern Hemisphere, would be my guess, more sublimation, more dust dispersed.
On the head lobe seen in image D, there is bright white cryorock at about 285 x 240. The plume of gases rising off the top of this reaches to the horizon. Moving down and right of this point is an expanse of broken, rubble covered terrain, from which numerous narrow jets are shooting straight up.
There is also activity on the body lobe. This one I have not seen before. Best seen on the slightly raised contrast of the large mosaic at about 870 x 230 (the large mosaic is 1700 x 1400 pixels). This feature on the horizon appears to be a curtain of gas and dust presumably from a fissure of some description. More plumes can be seen near the bright spots just below the horizon in the middle of the body lobe at about 710 x 230. Three of these plumes can be seen to be rising from little dark pits, the much searched for vents perhaps.
On the left of the head lobe there are three bright vertical sheets separated by chasms. They look a bit like corals growing out from a reef. Some other most peculiar shapes and formations in this area unlike anything seen before.
Looks like Philae is going to land just before things really start to get going. Day off work booked and getting all set for the big day.
If sublimation were the cause of the jets, wouldn’t we expect at least some water ice to be found on the surface of the dark regions of 67P? I can’t say it enough… there is no need to stick to sublimation when electrical processes can account for all the observations.
I think the most important difference between electric comet theory and sublimation is the observed erosion. Without any doubt, this is a clear prediction of EU theory which gives standard models some explaining to do. In a sublimation mechanism, I’d expect much larger boulders to be emitted from the surface, with large roughly shaped collapsed pits being formed continuously. Eroding the comet in a particular location by removing tiny grains from terraces, scarps, and cliffs is exactly what the electric comet idea proposes.
No need for sublimation, you’re simply biased if you see “plumes” or “vents” just as a Sci-fi fan would surely see Bigfoot in the woods after being followed by possible UFOs.
True Ross. I would have expected them to have specifically targeted the jets for analysis by now rather than just taking pictures, as they are fundamental to the comet mechanism. All they have to do is be able to distinguish plasma from gas. Not difficult. Then focus on the detail with that certainty established. Why would they not do it I wonder. Or perhaps they already do have that result.
The dust jet images get better and better!
Here is an enhancment of Claudia’s 4 Nov Navcam Montage of the Polar Dust Jet activity at a very high phase angle with sunlight forward scattered through the dust jet.
Image Source: ESA/Rosetta/NAVCAM CC: BY-SA IGO 3.0
https://creativecommons.org/licenses/by-sa/3.0/igo/
https://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Dust-Jets/i-FStX8M5/0/L/Comet_on_4_November_NavCam–enh1-L.png
–Bill
And, of course, interesting comparisons can be found in my “Dust Jets Gallery”
https://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Dust-Jets/
😉
–Bill
Nicely done again Bill. In the original image it was not altogether clear that a jet coming up from the neck was the cause of the large outflow. As Dave says its become pretty clear how the vast flat sides , cliffs, of the neck area have been formed. I notice there still considerable collimation after the jet has been redirected by the cliff face, the idea of internal magnetic fields from moving charged particles seems the most plausible explanation. The physical process of passing through the Reglisse may well create the original collimation, which is then reinforced by the alignment of any plasma and statically charged particles in the flow, creating a helical magnetic field, preventing it from dispersing until its density reduces to a point when the field strength is no longer sufficient to retain the cohesion of the column.
The curtain of material I spotted is shown more clearly in your image. I can only liken it to the curtains of lava seen erupting from volcanic fissures, seen most recently in Iceland. A whole different process and material but the visual analogy works for me.
The magnetic field would not be helical, it would have a direction and the charged particles would move helically through it. However, that is not what’s observed. The particles within the jets are confined and moving linearly away from the comet surface. This exemplifies the presence of an electric field, which can only be caused by charge separation. The comet nucleus is negatively charged; any charged body in a plasma environment becomes engulfed in a Langmuir sheath consisting of oppositely charged particles, in this case hydrogen. This is the source of the jets, no hidden interior ices needed at all.
If we just had some measurements of magneto-resistance.
I hate to disagree, but a current moving in a straight line, in a wire for example, creates a magnetic field perpendicular to the direction of the current. To do that it creates a circular magnetic field around the circumference of the wire, or in this case the stream of charged particles. this has been known since the 1830s and can found in any textbook covering Electromagnetism.
You assert the comet is negatively charged, from what measurement of 67P do you derive that assertion? I am not saying it is not, butI would like to know how you know that it is. You also imply that what we see, is Hydrogen. Hydrogen is an invisible gas. Again where are the results showing the presence of these large quantities of Hydrogen, either on the surface or in the coma? I am happy to concede charge separation between surface and coma is likely to be a mechanism that determines the direction of the jets, perpendicular to the surface, but without evidence it can only be speculation.
Robin, whether or not it is hydrogen ions, if the current density is sufficient it would exhibit glow mode.
Also, the negative charge attributed to the comet is based on the sound theory, backed up by much evidence, of the charge distribution in the solar system with the Sun as an anode.
Feel free to disagree, that’s what a debate is for.
Your quote, “which is then reinforced by the alignment of any plasma and statically charged particles in the flow, creating a helical magnetic field”
This is wrong. The magnetic field is not helical, it is perpendicular to the electric current which you later stated correctly in your recent post. The jets are already under the presence of a electric field, which causes the rays to protrude from the nucleus. Anyone with a background in electrical physics could infer the comet is a charged body based on the x-ray production, tail movement in the coma, and exploding comets traveling away from the sun… however, Cassini’s visit of Hyperion revealed that the moon is negatively charged as the spacecraft received a shock from over 2000km away. If a moon can maintain a charge, then a comet orbiting on an elliptical path through the sun’s electric field would certainly be charged.
Also, hydrogen can be a gas, not always a gas. It is not a gas in solar wind, it is a plasma with an electron stripped from the atom, leaving it positively charged and dependent on electromagnetic forces, not simply thermodynamics. Search for “hydrogen envelope” or sheath and you’ll find plenty of information. Not speculation, facts. Sublimation is speculation, vents are speculation. This has been identified by NASA in the following link, scroll down to 14.6: https://history.nasa.gov/SP-345/ch14.htm
The same mechanisms can be attributed to the “plumes” on Io, Enceladus, Europa, and other moons. The same electrical scarring can be observed on all planetary bodies; the enormous, anomalous crater of Mimas is a great example of an electric discharge providing a much better explanation than impacts.
@Ross, like this: https://www.jpl.nasa.gov/news/news.php?feature=4340 , sounds reasonable. Charge moves in mysterious ways through near vaccum. Lets cross our fingers for Philae and Rosetta to get some facts out. If something really groundbreaking is detected, I guess it will be chewed upon for ages before spit out.
Hi Ross. Don’t remember any ESA comment on X ray production. Do you?
Thanks a lot, Bill. 🙂
Is it just me? No soul else see the basic polyhedral shaping of this thing?
Show us. You have a photoeditor?
Hi Jacob. I’ll do the work if nothing is said at landing conference.
Both lobes are not ’round potato’ shaped. They have vertex. Vertex on both lobes are aligned. In Bill’s high pass enhancing work some flow can be seen going from lobe to lobe.
Fantastic image!
“The smaller lobe of the comet is seen in the foreground and the larger lobe behind.” — Are you sure?
I am pretty sure that the the smaller lobe is in the upper left corner and the larger lobe is in the lower right corner.
Oops, sorry! That’s correct, Cosmo, thanks for spotting it. It was quite late yesterday when the images were posted (so many things to prepare for next week!) and we got turned around. The text has been updated now.
If the white blobs drifting above the comet are for real or not is quite easy to discriminate. Is there nobody at ESA skilled enough to analyse a couple of images in row to give a proper answer?
On a previous NASA comet mission it was noted that there were fluffy snowflakes the size up to a third meter in diameter drifting in the coma and due to its almost 100% albedo clearly noticed.
Possibly someone at ESA could check this and smarten up.
By the way it was said to be fluffy snowballs and not ice so Philae has no need to worry if colliding with one of those shapes, although it might influence the accuracy of its targeting. Maybe it can take a snapshot if passing one on its way down. Can its cameras be set to auto-detect and capture?
Don’t distract them, Cometstalker. [They’re making ‘papers’]
LOL. 🙂
Someone said that the job isn’t done until the paperwork is finished while sitting on the lo watching his golden shoo.
Binary or not, it will not split in two and if the neck is eroded away in the future, the neck will collapse and the two parts will still join but in a new shape as they will rearrange themselves the best they can. Is it thereafter a binary? Has this scenario already happened once or twice?
Good point that Cometstalker. The neck area is eroding very quickly on a geological time scale and if that erosion does lead to two objects that recombine, I see no reason why that could not have happened on a number of occasions before. It might explain the shock compression leading to stratification of the ice, that was noted early on. The caveat to that is that this rapid erosion may only be the result of 67P’s recently changed orbit taking it closer to the Sun.
Is it thereafter a binary?
A re-fused twin 😉
The two things of the comet might be practicing kamasutra in a huge time scale just reached to page 7 in the illustrated book.
Bill,
With out you where would we be. I hope the ESA PR department wakes up and pays you a fee for all the work you have done to clean up their photos.
Great picture again.
Thanks
Dave;
I’m not quite sure I understand the point of your comment. We could obviously release multiple versions of the mosaics here on the blog to emphasise different features, since we have a reasonable idea what we’re doing when it comes to image processing, both in terms of scientific imaging and digital photography.
However, that’d make for a very cluttered post and so we prefer to release just one representative mosaic each time (or a montage, if the comet rotation/translation is too large during a NAVCAM sequence to allow make a mosaic credible). Quite a lot of work goes into making a decent mosaic and then trying to bring out as much of the huge dynamic range as possible in a single image, and we think the version we release provides a good balance of features and “drama”.
But that’s exactly why we’ve started releasing the images under a Creative Commons licence, so interested and talented people like Bill can create their own versions and circulate them freely, as he’s doing. It’s also why we provide the four individual JPG’s for people to have a go at making their own mosaic or perhaps using them to generate a shape model, as Mattias Malmer has been doing.
As for Bill’s latest image being “cleaner” than ours, there’s a trade-off. If I’m right (and please correct me if I’m not, Bill), some noise reduction has been achieved by binning the mosaic from its original size to something that’s 2.33 x smaller in both dimensions. Perfectly reasonable thing to do, but it obviously comes at some cost in spatial resolution. He’s then pushed up the background and the shadows to get a more detailed look at the coma, but at the expense of a grey sky.
So for emphasising the jets and low-level surface brightness stuff, Bill’s mosaic is great, but for a more detailed look at the surface features, ours is perhaps preferable (so long as you click through and get the full-resolution version).
Anyway, horses for courses, as they say. We’re happy for the community to take the NAVCAM images and play with them, but it’s not quite fair to turn around and accuse us of not knowing what we’re doing while we’re under great pressure at the moment and have very limited resources.
More or less everything you see coming out from ESA on Rosetta (images, blog posts, animations, press kits, social media updates and uploads, graphics and technical drawings, timelines, website updates, online hangouts, physical products like posters, pins, stickers, and so on) comes from a very small team of people who’re hugely dedicated to doing the best possible communications and outreach on this amazing mission, while also having to do the same for all the rest of ESA’s space science missions.
And when it comes to images, data, or results from the scientific instruments, we can only publish what we’re sent by the external science teams. Same goes for interpretation of the images and data: we rely on the external scientists for most of that.
Thus, to be honest and at the risk of sounding a bit whiney, it’s a bit dispiriting to see that some commenters on this blog tend to approach everything with a degree of needle. We’re doing the best we can.
Hi Mark. Taking my part in this attention call. Tend to forget you are small teams 🙂
@Mark McCaughrean, Cc Dave, In Daves comment I read only appreciation for Bills photoshoppin’ and no criticism towards the blog-team – but no appreciation for your work either. You deserve that appreciation, and I totally agree with your views on presenting photos. I think Dave does too.
A handful of comments with a negative criticism, coming from me, have hit your screens, and have passed your moderation. My criticism has been directed towards the ‘nondisclosure of data’ and somehow that criticism gets nowhere beyond the moderator and therefore ends up as a strike towards your loyalty to your employer. I realize you have no say in the matter of public acces to scientific results and data.
I do appreciate the work you do. I also admire everyone contributing to the whole mission. After all securing the collection of data goes before satisfying this little crowd 🙂
A way to reduce your burden would be to release raw data as this only takes the time to add a timestamp an a short headline, this of course depends on if you relay of the trustworthiness of the audience and their capacity of making something essential out of the giveaway. I Think i would do so if i had the possibility to do this.
Another way is to direct a note to the project management as it is this persons duty to arrange the resources needed for a project. The PR is a part of the project that is important as it for sure will influence the financial properties for this and future missions. A smart manager should have an open mind and ear to this. Possibly there are other ways to increase your capacity and one brainstorm tag is to use the huge amount of dedicated free of cost community, its like open source, just se what Linux has become since it started in a tiny group and now has i think more then 100 branches in its tree ( I’m using fedora if not in IOS ).
Any other suggestions on board?
Exactly, Mark.
You all are doing a good job with the images you have available to make public. And generally they are good images– full range and at a generous resolution so they can be worked with to show various aspects of the data.
Your efforts _are_ appreciated.
–Bill
Nice to here from you again Mark. I think it is a credit to yourselves as moderators that we get to see all opinions. I for one have tried to aim any criticism at the policy makers rather than the ESA outreach team. We have had a steady supply of NAVCAM images to fuel our interest and the occasional treat of some science, but it is frustrating when we know there is more information that could be released to you and the outreach team. The interest and enthusiasm of many of us, is no less than yours This is the first ESA mission I have followed so closely with ESA after a few with NASA and I’ll take your efforts over theirs anytime. All the ESA personnel we get to know are real people, honest, funny, relaxed and genuinely enthusiastic about their interest in space. I do hope ESA doesn’t become institutionalised and straight laced like NASA.
I guess naysayers and those with other agendas are an inevitable consequence of your success in stimulating such great interest in this mission and making it possible for us to get involved. A big thank you to Emily, Claudia and others for their work here from me.
Thanks so very much for all you are doing to keep us informed.
This is the best piece of public outreach ESA has ever even attempted, let alone accomplished with style.
I too, would like to see more of the hi-res images, along with a little more info on the plasma experiments, but i understand you can only package and pass on, that which you actually receive.
Thanks to everyone on the team, you are doing a great job !!!
More crystal-clear evidence of stratified rock formations at the top of the smaller lobe, a bit like contour lines on a map or an aerial view of agricultural terracing round a hillside.
And please don’t tell me again, anyone, that it only LOOKS like stratified rock and that our eyes are deceiving us… People on this blog are quite rightly spending hours scrutinizing the tiniest pixel-sized detail of the surface for the slightest clues, so I don’t see why we should at the same time deny the reality of much larger features, whose essential characteristics simply leap off the photograph at us. Selective vision is only credible up to a certain point!
https://en.m.wikipedia.org/wiki/Rock_(geology)
So it is not granite for sure, lets call it cometary rock as this fits the bill. Like in earth rock water is found in cometary rock some ices will be found as well and im sure if there is some empty space inside it is of minor volume but still cavities are possible. The only difference is that cometary rock never was a volcanic hot magma.
Sedimentary rock requires the presence of a liquid from which sediments formed by erosion, precipitate and solidify over long timescales. The temperature of 67P is around 200K, that rules out liquids on the comet for the required timescales, hence sedimentary rock also. That just leaves accretion of minerals and silicates in space to form rocks as the form that cometary rock takes, that is not like any rock found, other than in meteorites, on Earth.
Portland Cement was a manmade “Stone” made from a water based binding agent and fine particles of crushed Limestone and clays. It is used in vast amounts in the buildings of London as a cheap alternative to the expensive and limited supplies of Portland Stone during the 19th century. If we replace the Limestone and clays with the fine grained mineral dust of the comet and the binding agent with volatile ices, add in some darker colour from the organics, what we get is a dark solid looking material that looks a lot like “rock”.
At these temperatures it could be looked upon as “Cometary Concrete”. The ratios of the components will determine its physical properties, more dust it becomes softer and crumbly, less dust, more crystalline and brittle, more organics or greater exposure to radiation, it becomes darker. This is the nature of Cometary Rock I propose. It would become more porous and friable over time as any trapped gas and the very volatile ices sublimate from the mixture, the structure being maintained by the dust, organics and less volatile ices. Once all the ices have sublimated away, a pile of Reglisse is left behind. This would slowly accumulate over time as long as the sublimation rate was very low.
Once 67P changed its orbit to then receive vastly higher amounts of Solar radiation, the gas pressure of the sublimating gases would be sufficient to start removing the dust from the surface and into the coma. Areas under the insulating layer of Reglisse still would not reach sublimation rates to disturb the dust, its porous nature still allowing the slow diffusion of the small amounts of gases that are created in the subsurface layers.
The Northern hemisphere receives less solar radiation, because its summer is in the cold part of the comet’s orbit, so here we see the vast plains of Reglisse still in evidence. Hints of a different appearance in the more southerly regions of the comet suggest the far greater amount of solar radiation in its summer (during Perihelion), is sufficient to overcome the thermal insulation of the dust layer and create a gas pressure sufficient to displace the dust. On the as yet unseen “Dark Side” of the comet there may well be very little dust left in the Reglisse and a only a black lustrous coating of tar like organics left to cover the surface. This may only serve to increase the amount of energy below the surface and its sticky nature seal in gases leading to pressure sufficient to allow the subsurface to plasticise and allow extrusion or even melt to form Cryomagma.
There, a grand fudge to try and keep everyone happy, which probably means everyone will have arguments against. 🙂
A penny worth of liquorice: Lakritz. It’s a more ‘concrete’ word. Cheers!
Interesting point here is that ‘terrestrial’ cements are structurally half glass and half crystal. That extraneous property makes them resilient to fracture, self-repairable up to a certain point and slightly ‘pliable’ 🙂
Your surface ‘cement’ would have to be kind of ‘rotten’ as there is so little remaining ices there.
And more than the water, you need the ions, lots of ions.
Yes “Rotten” seems a pretty appropriate word, its already full of tiny holes and as the ice disappears near the surface, we see cliffs and ridges crumbling into piles of rubble. Once the ices go the material falls apart. There are places where the dust seems to be “clumped”, the last stages of breakdown perhaps?
Like I said its a bit of fudge, but after a while it seemed it did fit some evidence at least, enough for speculation anyway. The trouble is I am now impatient to see more of the “Dark Side”.
To build sediment like layers without water is possible.
In the micro scale tyny particles tend to lump together and the bigger structures do so as well.
Something that reminds of sputtering could be possible.
Or like making pyrolytic carbon or boron-nitride as vacuum and moderate speed ions can do the job.
The dust grains can be bonded by sublimating ices in different layers.
There are a lot of possibilities to create structures that give the visual impression to be rock like, or even snow like without being anything of it and not like what is present on earth.
I hope Philae is resolving this issue and i also pray that the information will not be watered down to a meaningless note.
If ESA really wants to make fiction into science as was claimed then it is about time to start to move in that direction.
For a few hundred years ago it was not possible to make a lot of things that kids of today are making in classes and also understand to the full what it is all about. This is not due to any increase of intellectual capacity in the human brain as this has not ben altered for the last 10000 years.
The learning processes did change and the information capacity has inflated due to improved communication.
This can still develope and improve and should not be blocked by some stupid and meaningless policy.
Robin, you say “Sedimentary rock requires the presence of a liquid from which sediments formed by erosion, precipitate and solidify over long timescales.”
I don’t see why you refer to “sedimentary” rock. I’ve only ever talked of “stratified” rock and Emily speaks of “layered” rock. These two latter terms are merely descriptive of the rock’s visual characteristics and suggest nothing whatever about the precise nature or origin of the rock. The term “sedimentary” on the other hand denotes, by definition, a water-based origin.
If I had to use a more prescriptive term, I would plump instead for “metamorphic”, since the totally jagged aspect of the rock formations we observe are much more reminiscent of slate (for example) than of limestone (for example..).
It will be very exiting to see when this comet splits in two or more pieces. Hopefully Rosetta is then still fully functioning so that we can really see what is inside.
Seems so dynamic! Mere insolation levels change surface morphology.
That ‘bright’ spot is no doubt mostly water.
The slow, repting, cold gas draining down from the big ice is generating his own ‘stream terrace’.
https://directory.eoportal.org/web/eoportal/satellite-missions/r/rosetta
This is a very nice link worthwhile to study and has quite a few spoilers about the rosetta mission.
Note the option of the Philae bombing trajectory correction with its thruster.
I believe that has been discussed by ESA, especially after the change in comet target and the greater gravity of 67P was factored in. I think the decision was to save the fuel just in case. The time delay for instructions and feedback had a lot to do with it too. I do remember Andrea Accomazzo answering just such a question during the arrival events. He did not rule out using it in an emergency though I seem to remember.
Thanks for that link Cometstalker. An extremely illuminating article. The Rosetta and Philae science teams are going to have access to highly detailed, accurate and revealing data. There is some serious kit on this mission. Pretty much every base is covered, many with more than one instrument, including much data some here claim is not being considered.
They have clearly thought very carefully about what they expect to find and how to eliminate random and known possible interference agents, but with the flexibility still to investigate the unexpected. It is all still working flawlessly after 10 years in space, that is some achievement in itself.
It is clear the data available from these instruments can give a lot more answers than we have seen so far. I totally understand your frustration at the minimal science data revealed up until now, but how much of this is the general public going to understand? A decision has clearly been made to make the science reported more relevant to the non scientist, which I understand, but as a scientist I’m feeling a bit shortchanged. There should be a critical mass of data that enables definitive conclusions on some basic aspects of the comet to be made.
It would seem that point has not yet been reached. The hangout on Friday gave a summation of what has been found so far plus a couple of extra teasers, which was welcome, but unfortunately that leads me to think Wednesday’s science briefing, will be much the same, just a bit more longwinded. Lets hope some one is prepared to tell us some basic early conclusions too. A great deal of effort has gone into generating interest and explaining the questions Rosetta is looking to answer. The public ARE interested and the pressure on ESA to come up with those answers is the result.
Not only inter-national, inter-generational.
Based on the stratigraphy we’ve seen this far, C-G is a contact binary or two morphologically different chunks that accreted during the, uh, accretionary process(es). Either that , or the sublimation/deflationary processes exploit zones of weakness between terrains– we’ve seen too many “binary” objects moseying through to be coincidence.
A topsy-turvy world full of surprises…
–Bill
Hi Bill. When I saw the first 3D OSIRIS ‘yelled’ about two comets for the price of one voyage.
I beg you to look at this photo bellow and think about the geometry of what conform the limits of the ‘neck’.
https://www.esa.int/spaceinimages/Images/2014/10/Comet_on_2_October_NavCam
Really would like to know what do you think of this, in your modeling.
I have been browsing some stuff on macroscopic voids in comet nuclei, and I was wondering how big these voids can get to be. Can one imagine that the whole “neck” was once “roofed” and formed one of these voids inside the nucleus? Suppose this is possible, presumably it was the last perihelion whose heat burnt off this roof and the collapsed parts made the neck surface that we see today, covered by smooth dust.Would the activity caused by this collapse be so strong that it continues as some relatively gentle jets even today before the Sun has really got to work at the next perihelion?
I have been thinking along similar lines Kamal. The solid cliffs at the sides of the trench might take some explaining though. I think the reason for the jets being in the neck area is likely to be in part due to extra energy from tidal forces and also the exposure of material containing more volatile ices previously unexposed towards the centre of the comet. Most of the volatiles near the rest of the comet’s surface are likely to have been lost during earlier orbits. Higher amounts of solar energy are needed to reach the volatiles deeper in the subsurface layer.
It could be postulated that such a collapse soon after the comet’s last closest approach to the Sun is an explanation for the apparent measured change in rotation rate since 2009. Just such a fundamental change in mass distribution would be needed to explain such a change.
Robin: This should be testable, there must be a similarity between the two sides of the neck which would be hard to explain if we had a contact binary instead.
Interesting streaks on the coma. It makes me realize one thing I have not read yet here or elsewhere: whether dust is escaping the comet with a roughly isotropic direction or not does not affect the fact that by moving away from the comet surface, the average speed of a dust particle becomes smaller than the rotation speed of the outer parts of the comet: we get local dust winds of particles coming from closer to the rotation axis (i.e. with a lesser tangential speed), hitting other parts of the comet with a larger tangential speed (because they are further away from the rotation axis. So there are probably “dust winds” on parts of the comet away from the rotation axis, even without external forces applied.
yes, and you will find that discussed in earlier blogs (don’t recall which) also the amount and composition (larger particles?) is discussed: ‘coma fallout theory’
Recent enlightenment from the article recommended by Cometstalker above, says Rosetta has instruments to measure dust leaving the comet’s surface, its velocity, flux, momentum and mass as well as dust heading in the opposite direction due to interaction with the coma and the Solar Wind. For material close to the comet’s surface, there are instruments on Philae that can measure the dust falling onto the comet too, both on her way down and when she is sitting on the surface.
We will find out Jacob if there are hailstones, how big they are and where they come from. Seeing the objects floating about near the comet, I am thinking more in terms now of dusty bits of fluff a few centimetres in size. More like giant snowflakes than giant hailstones.
Hailstones are just a wild experiment of mine 🙂 what should be for certain is some ‘dust wind’ happening near the surface.
I did calculate what happens if an object is dropped from a radius of 1500 m to a spherical dense mass the size of this comet with zero initial speed, it takes 81 seconds to travel the first vertical meter. If the real thing is simulated like the fast rotation period and the odd shape and some Coriolis effect plus dropping it from 2000m radius with some small initial speed vector and then some solar wind and electrostatic charges it gets to wild to do the effort.
Drifting dust is an understatement on this place, its more like ultra slow motion 3D rave party.
Well said Mark McCaughrean.
I’m sure a great many of us blog followers agree and sympathise with you all who put in a great amount of work for our pleasure.
I’m afraid there’ll always be the, let’s say ‘ less appreciative’ as well as those ‘armchair astrophysicists’
Rotation period
12.4043±0.0007 h (current)
12.76129±0.00005 h (before 2009 perihelion passage)
These are some figures i found making me a bit edgy.
Apparently someone got an accuracy of the comets rotation period a magnitude better without an orbiting satellite. This is aether a hoax or the new rotation periode is crippled in its accuracy two magnitudes or more also meaning that it is possible to measure changes of its rotation period in a montly update.
@cometstalker In 2009, comet C-P was close enough to Earth, and active enough for detailed spectrography and other Earth based observations. Research based on these observations (Published in 2012, I believe) calculated with a great degree of certainty the rotation state at that point near perihelion. It was only the combination of detailed multiple Earth based observations at a time of highest activity, that could confirm this. Thus no possibility to see what the rotation was in between 2009 and 2014. It is obvious to me that activity near perihelion and beyond has increased its rotation rate. This is no hoax, and rotation rate should be expected to change again at perihelion.
The increased activity of the comet, must have changed the mass and its distribution on the comet and some propulsive thrust from more vigorous jets is a likely cause too. Kamal’s idea of collapsing voids in the porous structure of the comet could have had an effect too, resettlement to a more compact volume if you like, especially in the neck area. One such resettlement could explain the late April early May outburst in activity, and the unpredictable scale of the activity of comets in general.
What is interesting is that the rotation period if measured with high accuracy gives information of the comets mass loss due to the increasing coma and also can indicate structural changes due to preservation of the rotational momentum. Its useful in a lot of ways and with the orbiter it must be easy to get a very high accuracy. The periodic rotation change from one orbit to another is quite high and i think it is mainly due to contraction as the neck region was active from the first close (150km) sighting. The frustration increases due to the knowledge that the science teams will not release even fundamental and for sure not carrier blocking information in a stubborn way. I met a few scientists and there are two extreme fractions, one that give away just about anything without hesitation and the other side that hide absolutely everything. None of those where good scientists. The science teams working for ESA tend to be the collector type piling information and do their research in the shade and only give away small bits of no value also far away from their goals. For example the fallout in the coma creating fluffy snow shapes the size up to 30 cm already have been noted on a NASA comet mission and it is quite clear that even on this mission there are shapes floating around, so this is nothing new and could be presented in a short form as no one in the science teame @ ESA is able to get the credit for such an event anyhow. Or if the density uniformity has anomalies is not science but only a measurement and 0815 calculation result. The picture this behavior displays to the outside is that there are persons in the science teams with very little confidence and possibly lack of competence, even if this is wrong the picture is framed and hangs on the wall.
I am prepared to allow some leeway for the science teams. The majority of their efforts have been directed towards analysis of the landing site. I shall reserve judgement until after Wednesday’s events and science briefing. Fridays hangout made a point of saying that the imaging teams are willing to release images taken during the landing. I got the impression some persuasion was involved to get those assurances and note has been taken of unrest about the lack of OSIRIS images.
The documentary on National Geographic about Rosetta tonight showed the lander team testing out the effectiveness of the harpoons on a simulated surface based on what they had learned since arrival. The material they used was a particulate wall insulation material, a gravel type material made of foam. The harpoons did work, but withdrew over a metre before they gripped under only 15 Newtons of tension. We did not see what happened with the ice screws, which they must have tested as well.
I suppose the internal science teams have open ears and are prone to change their behavior, but the external teams will not be influenced as they are far to eager to get some credit out of this mission and are not willing to share as they compete in a jealous way hiding inside their reveres. The proportion of the mission goals is that Rosetta is worth 80% and Philae has the rest i did read somewhere. I do not agree with this and think it is rather 50/50 as some synergy effects will occur. There is lot of information presented like being a rumor, for example that the gravity distribution is well documented. Why then not say this in a way that has some deeper thoughts about it. Like due to the —– we estimate that —– with confidence. Or some thermal maps presented in a way that is meaningless for the broad mass. Its not hard to do this in another way like Mattias has done, draping it over a shape model and at one instant flash it gets clear to 99.9 % of the audience what this means.
I still think that it is a lot of sloppy workmanship going on and it could improve if the know-how is combined with a bit know-why.
There are, thanks heaven, persons in the audience that do a great job with the material presented and so far i would give those persons the majority of the credit.
To use some instruments and perform some experiments and to calculate some trajectories, make a few adjustments and loop back again is not really science its more a task for engineers and technicians to do a proper job. The science is, as i see it, when captured data is used in a way that explores new ways of understanding some processes and events and of course to confirm some ideas or knowledge that was present prior to this mission. So far we are witness to nothing more then the confirmation that the instrument behave as planed. This is of course a gigantic hurray for those people that made this project possible and i would like to be able to deliver an equal big hurray to the SCIENTISTS once they deliver something with ESSENCE, it is sad that we due to a lot excuses not yet have reached this stage in the mission planing.
I have no issue at all with the scientists. There certainly is no “conspiracy”, and if there was, some information could be “leaked”. I am quite excited about studies of the rotation rate. I have read up a few cometary studies, and research done on the rotational state of 103P Hartley indicate that it is likely to split apart due to the activity of jets altering the spin. At this point, any calculations of spin are about accurately getting Philae down. The holding back of scientific data and images makes the scientific conclusions all the more dramatic and momentous. I believe the most interesting things will take time to see closer to perihelion, so patience is still key.
Patience is one key of burden but proper presentation is another key that can be done right now and does not add load to patience. The example with the thermal maps in long-lat format is not for the broad mass, the little extra it takes to present this on a 3D shape is not an overwhelming task and if done it improvers the quality of this presentation several magnitudes. Its hard to accept that so little effort is done with the presented data and if the resources to do this is limited in some ways it would be better to additionally present the raw-data in a box where dedicated persons can give it a try and present the edited result. I have seen a lot of work done by audience that is of a higher class then the ESA was able to present and this with already crippled data to start the work with. I am quite sure that no conspiracy is present and leakage of information is also not an issue. The main issue is that the presentation that ESA makes is focused on drama and not science. How hard would it be to show a picture containing streamers with an overlaid thermal scan and do so once or twice again a bit later to presenting the dynamic variation. This would include drama and science. Not to do things of this or similar kinds is not due to policy whatever, its more a lack of ambition, fantasy and creativity. So far the navigation team is the one that is the top at ESA and does a great job, for the rest i see a lot of improvement possibilities.
Mark ,
Sorry I upset you.
We are hugely appreciative of the rosetta mission and the effort from every one concerned in a hugely ambitious and successful mission. That includes the photographs.
However just look over the blogs, people are desperate for more information including higher res pics. Sure we know why we can’t have them, but that does not help our frustration.
We are also desparate for better data, that which given is often short on information
My blog was to encourage bill to keep going, he obviously loves producing the images.
Again look at the blogs every one is guessing which is fun up to a point, so it would help to have a bit more info, so that the scientists among the bloggers can initiate more of an informed debate.
We are of course thankful for every bit of information we get
Thanks, Dave, and to everyone else higher up the comment stream who expressed their positive feelings about our outreach efforts. It’s appreciated.
It wasn’t so much that you upset me, although yes, the tension is high and admittedly our nerves are a bit raw at the moment too …
It was more that I felt I’d take the opportunity to try and give a bit more background to what we’re doing (and where the limitations are, both in terms of resources and workload on our side, and the availability of images, data, results etc. from the external scientists).
Of course, it’s only fair to point out that they’re all hugely busy too, in part preparing for landing, in part trying to work out how best to operate near this crazy object, and in part trying to get science results together and published as soon as possible.
As for reading the blogs, I can assure you that we read every single comment posted on every post. We’re interested in your opinions and ideas, but can’t always reply to comments, mostly down again to time limitations.
There are also many comments re: wanting higher-res images and so on where there’s not much point us repeating what we’ve said on several occasions and as I have here, namely that apart from NAVCAM images, we can only publish what we get sent.
We understand the frustration, but hope that for your part, you understand that we’re doing our level best.
Big week ahead of us, everyone; see you on the other side 🙂
Would love to see some thermal images 🙂
All of the crowd is with your wish, Tammy. 😉
In celebratory anticipation of the landing of the Philae spacecraft, I have prepared a series of Geomorphologic maps of the region around the Agilkia landing site.
These are the first two maps of the series: the base map and the preliminary geomorphologic map. More images in the series will be posted in https://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Geomorphology,
https://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Geomorphology/i-sdTCGzP/0/L/Agilkia_landing_site_mosaic–OSIRIS–geomorph-terrain_basemap-L.png
https://univ.smugmug.com/Rosetta-Philae-Mission/Rosetta-Geomorphology/i-xRx6w3h/0/L/Agilkia_landing_site_mosaic–OSIRIS–geomorph-terrain_basemap–annot-L.png
With further discussion and maps to come in Reply…
–Bill
Dave: I think we (the bloggers) are underrating how much work people are doing. I imagine that getting the lander safely down must be priority number one. If some extra bit of work from people in any of the Rosetta teams contributes to some help in that effort, that is worth quite a lot.
I like speculating about far-out things which the teams don’t have the time to worry about at present. For example: What will happen when the comet comes nearer to the Sun? So far we have had some discussion on-and-off about whether the two lobes will break up, but that is a big event. Can we guess where we are going to see a big fat jet emerge, like the ones we have seen on other comets?
I find it fascinating that the comet images, this blog and other blogs commenting on this mission, have made people get the ambition that they can juggle around with some science too. With interest at this level, it would be worthwhile to push for a wider public understanding of comet models (more broadly, planetary models) in the hope of getting younger people hooked.
We saw earlier on this blog a discussion on the differences between asteroids and comets. From the responses it was clear that this is an open question. Can density serve as a distinguishing characteristic, with the Centaurs serving as an ambiguous case where we don’t know the answer? (There are also some lighter-than-water KBOs, but I don’t know enough about things that far out.) Can we use this to increase public interest in a mission to Centaurs and KBOs?
I find the sustainability of craft like Philae and Rosetta an interesting question. How long can they go before they have to give up, either because of the end of fuel, or because they get destroyed by the comet’s activity?
Kamal,
I think we all know that the Esa staff have a huge work load, at times we get frustrated though.
I also enjoy the on the edge speculation on the blog, just as much as the more seriously technical or scientifically backed coments.
I also wish there was more public awareness, we have seen blogs from school teachers trying to keep school childrens imaginations fed.
There are only a few bloggers on this web site, when I speak to my friends they think I am a geek, even my son says I am.
It seems there is not much to interest a casual observer, maybe the landing will a large swell in interest.
ITS ELECTRIFYING!
A piece of information has been published from the Cassini mission, Its 9 years after the event, I’m not sure if its been published befiore and re-found or if this is the first time.
So waiting 6months for osiris images suddenly seems supersonic by comparison.
Anyway please read;
“CASSINI CAUGHT IN HYPERION’S ELECTRON BEAM”
Some highlights:
The new analysis of the data shows that Cassini was magnetically connected to the surface of Hyperion for a brief period, which enabled it to be bathed in a beam of electrons coming from the moon’s surface.
The Cassini data show that a similar process can take place on Hyperion. Due to its interaction with solar UV light and charged particles from Saturn’s magnetosphere, the moon’s surface may acquire a net electric charge. This is precisely what was found by Cassini’s instruments.
Analysis of the CAPS-ELS data indicates that it remotely detected a strongly negative surface potential (-200 volts) on Hyperion, consistent with the predicted electrostatic charge in regions near the moon’s terminator – the day-night boundary.
“The large difference in potential between the surface and the spacecraft resulted in a flow of electrons being accelerated from Hyperion toward Cassini,” said Tom Nordheim. “It was rather like Cassini receiving a 200 volt electric shock from Hyperion, even though they were over 2000 km apart at the time.”
artical by Rossim October 6th 2014 (Nasa)
This does really look like evidence for the EU model,
Also we know that on the Deep impact mission to Temple 1 , we saw a flash over prior to the impact and a spetacularly energectic impact into rock, much brighter than expected, this must be further evidence of the electric nature of our solar system and the bodies in it.
Siding Springs encounter with Mars, also looked a bit unusual, although all the data is not in.
The video clips appeared to show a flash as it went behind Mars, maybe camera flare, not much data is in yet.
However hidden from view, there was a massive meteor shower and a massive change in ionisation in the atmosphere. Was this just trailing dust? or was it caused by an explosive electric discharge, I am only guessing.
The evidence for electric discharge of bodies of all types including comets,within the suns solar wind seems to be growing.
Evidence from Rosetta also shows induced currents from plasma interacting with the Sun’s magnetic field and the Solar Wind. These are viable events in both models and in the case of Hyperion. Rosetta went to 67P with a dedicated suite of instruments to investigate these interactions. Cassini also had instruments capable of finding evidence of these interactions. It is to be hoped the data collected can define their scale and influence with experimental evidence.
It should be remembered the time scales involved in these missions. Scientists were thinking about and devising these experiments 25 years ago, based on evidence from early space experiments in the 60s and 70s. ESA’s first mission was to investigate the effects of the Solar Wind on the magnetic environment around Earth.
Dave, perhaps you could also add the multi-hydrogen-bomb-magnitude explosions which occurred high up in Jupiter’s atmosphere as EACH of the 21 constituent pieces of the disintegrated Comet Shumacher-Levy penetrated Jupiter’s magnetosphere back in July 1994. The explosion of each vanishingly tiny fragment left 21 huge scars on the giant planet which all remained visible for many months. That certainly wasn’t melting ice. And it shocked the socks off standard theorists.
This apparently forgotten event is summed up and reset in the context of the huge man-made explosion caused by the “Deep Impact” collision with Comet Tempel 1 (and its famously observed double flash) in July 2005 here:
https://www.thunderbolts.info/tpod/2005/arch05/050718deepimpact.htm
I think it would be a fruitful exercise for amateurs to try and figure out how people that may have spent part of the last 20 years of their professional life working on the mission, could reasonably feel about freshly self appointed experts demanding access to raw data, telling scientists how to do the job and pretending to be paid for one or two hours of the spare time they used to allegedly “enhance” some images.
… (time for the exercise)… ok 🙂
To make things clear, I am certainly not saying this kind of fiddling is useless (I do it myself at times) but let’s take it for what it is : an entertaining hunt for details that once in a while may have remained unnoticed in a large amount of data/images. Contrast/level adjustments, high school trigonometry and a heavy dose of wishful thinking are far below par when it comes to producing science.
So lets keep on with the fun but lets keep the sense of measure when claiming results or demanding support from the people who have actually been doing the real job for the last 5-10-20 years…
Ed, we were invited. If opinion has changed, just tell us.
Science as it happens is at her most beautiful point. Not when scholastics have said the last word, and text books have been rewritten.
Really happy for every bit of data some insiders have dropped down here. Sorry about the noise.
“…details that once in a while may have remained unnoticed in a large amount of data/images”.
Where are they? Will happily do the ‘dog’ work.
As I include myself in amateurs, I am certainly not in a position of (and have absolutely no intention of) telling anyone what he should do or not. I am perfectly comfortable with people fiddling around with available data. I was only suggesting to keep some basic facts in mind when expressing claims, demands or griefs to the teams.
And thanks for talking the ‘talk’.
“… an entertaining hunt”. Yea! Well chosen words. that’s how real teaching should go.
Isn’t ‘teaching’ one of the objectives of the Reaching Program?
We are constantly reminded that we are outsiders. Even the name of this program ‘tag’ us as such.
Ed. I think if I had worked for 10, 20 years on such a project and had managed to discover some new nuance or fact about comets I would want to tell as many people as possible, if only to validate spending all that time trying to achieve just that. The people doing the science are not the issue here, its those that fund their research who control whats happening.
I think that it can only be speculation and a bit of fun too, but others see it differently unfortunately. I might not agree with their approach, but they have insights and opinions to express which add to the learning experience, as Logan says everyone was invited. As taxpayers we pay the bills and some feel entitled to express their dissatisfaction. This blog is moderated and if lines are crossed then action can be taken or responses made, as has happened. How does ESA learn and improve if everybody tells them they are doing a wonderful, brilliant job?
Finally, the suggestion that someone else should be paid by ESA for their image fettling skills, was meant as a bit of fun and a compliment. Nobody claimed they should be being paid by ESA for their own work.
Ed: One of the thing that scientists don’t tell the public is how much of a dog-eat-dog world professional science is: if you let your data out even by a whisker, someone else jumps on it, publishes, your funder backs out, and your career is gone. We amateurs do not realize that science is far from being a Tintin-style adventure which you jump in with your sandwiches.
In some industrial branches this applies well. But in this mission the funder is you and me and we are not able to back out. Also the outcome of the science of this mission will not likely result in some expensive blue pills or other gadgets that will result in gold filled treasure boxes. The dog eat dog scientists all have a manager and this person is the one in charge to hire or fire. If i would be in this management i would demand a time plan and intermediate results to be able to update the project plan and adapt the resources neded to fullfill the mission, me to would have a boss who wants something presented.
The goal of this mission is already declared and and its direct purpose is to gain knowledge and not money.
In the background of course some thought are present to ease the way to get resources to additional missions and some persons for sure would like to improve their possibilities to make steep careers. Although the filter processes soon sorts out the losers and only the gifted will stay put. By the way im past the age of pension and do not longer compete, also my dog is friendly and stable on four legs.
“…also my dog is friendly and stable on four legs”. I would crowd-fund a research on the correlation 😉
The animal references have suddenly brought back to my mind (“I don’t know why…”) that old children’s song “I Know an old woman who swallowed a fly”. For those who don’t know it, after the successive swallowing of increasingly larger animals to try to catch their predecessors in the woman’s stomach, the song ends with the famous last lines: “”I Know an old woman who swallowed a horse. / She’s dead, of course!”
So goes it also, I believe, with the standard cosmological (and not just cometary) theory, which will somehow have to try to swallow the increasingly astonishing conclusions of this new Rosetta Stone.
Thanks for that bit of enlightenment, Lodaya. Didn’t know that still is that way.
What’s going here is mainly a ‘joyful’ educative exercise. Truly convincing people [and ourselves] of how important space research is. The less [informed] learning from the more. Discharging OutReach team workload a little. Obvious is that this can’t flow without a minimal data feeding. If reaching a critical size, in the process a cascade of intermediate discourses and lexicons [could] be generated as a benefit. This is a follower’s blog. Nothing else pretended.
Logan: agree with your outlook, also with Ed’s gap between the amateur and the professional, bridging that communication gap requires a lot of work which the outreach team is doing pretty well.