Rosetta’s view of Comet 67P/C-G on New Year’s Eve. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Happy New Year and welcome back to the Rosetta blog!
We’re looking forward to sharing more scientific discoveries with you as Rosetta continues to study Comet 67P/Churyumov-Gerasimenko in unprecedented detail, all the way up to its dramatic finale in September that will see the spacecraft conclude its incredible mission on the surface of the comet (read more about that here).
But first, to start the new year, check out the images of the comet published via the OSIRIS image of the day website over the holiday period – we’ve collected them together in an image slideshow, here.
Discussion: 120 comments
Happy New Year! Every Soul around this Endeavor. Welcoming OSIRIS to this Live Out-Reach Sharing Effort. This is going to be unsurpassed 🙂
An interesting choice of ten images emily, mainly very close and nondescript. Only two show any jet activity in the frame and one of these is the most informative. Captured on December 16th from 112 km it shows strong jet activity, at a distance of around 2 AU and 114 million kilometres further from the Sun than the perihelion at 1.24 AU. Once again also jets originating from and illuminated within shadow regions are evident.
Hard to ignore the jets and what they can tell us as they are the most distinctive and characteristic feature of a comet. And in May of this year roughly when the snow line boundary is reached we would according to the ice sublimation hypothesis expect perhaps to see a marked change in the jets when they become exclusively ice crystals, if of course there is any photon induced water emission at all. If the jets are other than of heated ice origin we would not expect to see any change at all at the snow line, particularly if they are from a hydrocarbon combustion source and exhibiting temperatures at 3 AU still well above the snow line temperature.
In any event still an interesting and hopefully productive year, or so, ahead during this important retreat phase of the comet orbit and before the termination landing procedure. May I ask if you expect to have any battery life left after that landing attempt and if successful would there be any possibility of any further communication with the instruments.
Hi OriginalJohn, I refer you to this blog post for your question on Rosetta’s “landing”: https://blogs.esa.int/rosetta/2015/11/12/from-one-comet-landing-to-another-planning-rosettas-grand-finale/
But in short, recall that Rosetta is solar power operated, and in any case it is highly unlikely that it will be able to operate from the surface for the reasons outlined in the last section of the above blog post.
Thanks for that emily. I missed that post first time round. A comprehensive analysis. I noticed the conjunction problem from studying your 3D model.
I look forward to the close in data gathered in the final phase of the mission.
Originaljohn, I’m not quite sure, whether the exposure times of the NAC images are documented correctly. But at least this NAC image is described as 4×4-binned:
https://planetgate.mps.mpg.de/Image_of_the_Day/public/OSIRIS_IofD_2015-12-23.html
This means, that the 16 pixels within a 4×4 matrix of CCD pixels are summed up into one pixels of the resulting image. This corresponds to a 16-fold brightness enhancement. The exposure time is documented as 0.5 seconds, in contrast to most NAC images with 0.192 seconds, if correct; another factor of about 2.5. Besides, some of the NAC images are taken through a filter, which further reduces brightness.
WAC and NAC may differ in their sensitivity under otherwise the same conditions.
So, faint features like the jets may be visible in some images, in others less or not at all.
@OJ
” And in May of this year roughly when the snow line boundary is reached we would according to the ice sublimation hypothesis expect perhaps to see a marked change in the jets….”
Not sure where you get this idea from. May will be 9 months post-perihelion. The comet will be at the same heliocentric distance as it was 9 months pre-perihelion. Rosetta was detecting H2O sublimation in June 2014, 14 months prior to perihelion: https://www.sciencemag.org/content/347/6220/aaa0709.short
So there should still be H2O detected 14 months post-perihelion, which takes us to October 2016, after the mission end.
It is not my idea ian. The snow line is a boundary defined by planetary science. Its exact distance is disputed but all figures are close to 3AU, in our heliosphere..
You have ian assumed an acceleration approaching perihelion that matches the deceleration of recession. I do not know off hand the figures for speed, acceleration or deceleration but from the ESA 3D orbital model, which would incorporate those figures, 3AU (450 million km) is reached around May. That webpage also has continuous update figures for comet speed and at any date from March 2004 to Dec 2016. A quick check has just showed me that 9 months before perihelion the speed was 19.5 km/sec. 9 months after it will be 18.35 km/sec.
Beyond the snow line water is by definition solid phase regardless of the pressure.
ps but not solid phase if its temperature is above the snow line temperature.
November 2014 was 9 months prior to perihelion. May will be 9 months after perihelion. Luckily, November 2014 was when Philae was landed on the comet. The distance then was 2.99 AU (see any of the papers in the Philae special issue of Science). So being at 3.0 AU in May would be correct. And to go through orbital mechanics again; yes the comet will gradually accelerate as it approaches perihelion, and will decelerate when moving away. However, it will take exactly the same time to move from 3 AU to perihelion as it will take to move from perihelion back to 3 AU (https://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion)
So you can choose any number of months prior to perihelion, and the comet will be at the same distance as it was at the corresponding number of months after perihelion.
Another way to look at it is being on a 400m running track. How long would it take to get from the 200m line to the finish if starting at 0 kph and gradually accelerating to 50kph? On reaching the finish line, you decelerate from 50 kph back to zero at the same rate as you accelerated, until you reach the 200m line again. How long would it take incoming and outgoing? What is the average speed both on the incoming and outgoing legs? How long did it take to get from the 100m mark to the finish? How long to reach that mark on the way out?
And 3 AU is not written in stone. Other factors come into play, including albedo. Comets are well documented to begin sublimating at around 4.0 AU (https://www.vanderbilt.edu/AnS/physics/astrocourses/ast201/snowline.html), so my point stands: no reason not to expect sublimation up until the mission end.
Well every reason not to actually ian if conditions conducive to sublimation do not exist beyond a particular boundary of pressure and temperature in the region of 3 AU.
The orbit is of course symmetrical.
I’m not sure this ‘snow line’ concept is terribly helpful.
Essentially three things come into play.
Firstly the water phase diagram. Easy to find on the web, but here it is in a different context:
https://everydaythinkers.blogspot.co.uk/2015/08/why-cold-drinks-sweat.html
This shows that at temperatures below 0 C and pressures below 0.06bar, ie 6000Pa, we need only concern ourselves with ice and vapour in equilibrium. Liquid could exist *transiently*, but broadly as you go to lower temperatures and pressure typical of the comet environment, it is harder and harder for the liquid phase to survive even transiently.
Then we need to consider the vapour pressure of ice. You can find that here
https://www.researchgate.net/figure/257515766_fig4_Fig-4-Water-Vapour-pressure-over-water-and-ice-and-the-three-stages-of-the
Or here in tabular form
https://www.kayelaby.npl.co.uk/chemistry/3_4/3_4_1.html
down to -100C and 0.0014Pa. Which is a low, but not very low pressure – a crude lab vacuum, not ‘space vacuum’.
Then we need to consider the latent heat of sublimation of ice
https://en.m.wikipedia.org/wiki/Latent_heat
It’s around 2.8kJ/g, not varying strongly with temperature.
Implications in a separate post.
Implcations.
Away from perihelion, only ice and water vapour will exist. Liquid would be at best a highly transient species, created by some local energetic event such as an impact.
At temperatures below 0C and pressures below 6000Pa – which the comet will certainly be at when not near perihelion, ice will sublime directly to vapour. It will ‘try’ to establish its equilibrium vapour pressure at its current temperature. But the universal vacuum pump will prevent that as the molecules diffuse away.
How much ice sublimes depends on the energy available to supply latent heat. That’s a balance between input (solar distance, geometry (inclination etc), albedo) and other heat loss (radiation at long wavelength, conduction). The surface cools and reaches an equilibrium temperature and sublimation rate depending on all those variables.
In principle, sublimation *never stops*. It just gets slower and slower. Since the vapour pressure is falling to very low values indeed by well below -100C, at some point it will become ‘negligible’. But this depends on what time scale we look over. At a given VP, the amount of ice removed depends on *time* too.
Broadly it will be true that somewhere in the say 2-4AU (rough guess) range sublimation becomes negligible on a small number of years timescale for vaguely typical cometary parameters. But there is no sharply defined distance at which this is true, case by case sum; indeed it could vary over the surface.
BTW in vacuum systems with internal water cooled components, leaks of water to vacuum occur; I’ve seen them a good many times. Usually the leak self-seals as it freezes. If you have a big pump, it’s possible to maintain a surprisingly good vacuum after the initial transient. The ice sublimation cools, it’s VP falls. Thie thermal conductivity of ice isn’t that good, so the heat input to the subliming surface is poor. This is quite closely analogous to ice on a comet.
Yep I have studied the water phase diagram on numerous occasions Harvey without the need of dumb analogies. Your analysis shows how the snowline concept might have arisen. ie the slightly vague boundary beyond which for all practical purposes water is only detected in the solid phase. It would therefore be extremely unlikely to see jets emitted from the nucleus beyond that boundary if ice sublimation was the significant jet forming process.
‘Analogies’ generally refer to the comparison of *different* phenomena to explain things.
Water ice subliming into a high vacuum chamber, limited by the available heat input, is not an ‘analogy’; it is direct observation of the same thing, under conditions not that radically different.
Anyway, broadly, yes somewhere out in the few AU range one expects the jets to subside – as they appear to be doing (note Rosetta is much closer in again) and as every other comet I know of has done. I’m not sure what the thermal models say about sub-surface conditions. That of course can delay cessation of activity if significant.
How sublimation drives the evolution of the terrain remains unclear. That it does drive it remains very clear.
Absolutely *nothing* has been seen in support of ‘alternatives’; not that they are ‘alternatives’ as their basic physics is risible.
Out of interest I did a bit of digging around.
I think the reality is that there is very, very little chance of continued operation after impact. But maybe not *quite* zero?
The solar panels are pretty certain to be destroyed, and would not be orientated to the sun; the high gain X band antenna can’t be pointed at earth; it’s fragile; dead……just maybe not.
They are four 10AHr 28V batteries. That’s a fair bit of energy.
And there is the S band isotropic antenna; just 5W output; it doesn’t have to point, and it would be much more damage tolerant than the high gain. It would have to be ‘in view’ from Earth, not ‘behind’ the comet to have any chance I’d think. The bit rate would be very low, and it’s not clear if it’s configured to transmit science data over that channel. It’s mainly used for control uplink and disaster recovery, not science data downlink.
But let’s say that channel survives and could operate off batteries, could any instrument work?
None of the imaging instruments will work, all focussed on infinity, so sitting on (or bouncing low over) the surface wildly out of focus, and not steerable. So no images or spectra.
Best chances might be ROSIMA, COSIMA and RPC.?
I stress I’m not predicting this will happen! Just that perhaps there is a tiny, tiny chance the S band channel could function for a while, if ‘in view’ due to comet rotation. But it might not be configured to transmit data from the instruments that just might function on the surface, and they wouldn’t last long till the battery dies.
Tiny, tiny chance, but maybe not exactly zero!
One further query, emily. On the 2nd January there was a long duration CME ( subsiding throughout about half a day) on the eastern limb of the solar disc. The brunt of it mostly missed the Earth but was heading almost exactly in the direction of comet 67P C-G. At 2AU it might reasonably be expected to reach the comet any time now if it has not already. It was also accompanied by a three orders of magnitude increase in proton flux in the 10 MeV range which at Earth has only today finally returned to normal day to day levels.
Have you observed any effect of this event at the comet, or do you expect to.
Originaljohn. Where did the data/prediction that is was ‘heading almost exactly at….67P’ come from?
Can you post them please?
I’m struggling to find definitions of the coordinate systems and vector, but *at first sight* it didn’t seem to be heading for Rosetta. However I’m not at all sure I’ve got that right, and would be interested to see the calculation.
No calculation Harvey and the estimate is mine from studying the ESA 3D model of the orbit of the comet superimposed on the inner solar system. You can find this by searching “where is rosetta now”. You would of course be able to represent the decelerating orbit of the comet mathematically but the CME would be more difficult. Remember it is not a single direction. It set off, however, in a direction close to 90 deg to the line from Earth to the Sun in the ecliptic plane. It is an expanding accelerating approximate sphere of plasma, which would encompass a large angle after it had travelled for 2AU.
Ah; we have rather different standards of evidence for stating that something is ‘heading almost exactly in the direction….’ I fear.
Yes Harvey, why do it the simple way when you can impress with imposed complexity and your grasp of it. By the time the CME front has travelled 2AU it spans a vast region of space. It is easy to see from an accurate 3D model if it might encompass the bit the comet is in.
Retry.
Because simple is quite often wrong in complex situations.
You need to be sure of your coordinate systems, direction, spread, are magnetic field effects significant, etc. Quick glance and make ‘exactly’ pronouncements is not my, or any other competent scientists, way.
I checked with the team and they say that *if* they encounter anything at all, it would be expected today. Let’s see.
I can’t access the article, but there was an event back in September 2014. I remember looking at the data in one of the papers around that time, and thinking that the SW flux was a bit high. I then checked the ACE data which showed a CME some days earlier.
The paywalled article is here: https://link.springer.com/article/10.1007/s11038-015-9479-5
I don’t recall anything of note happening at the comet, other than the increased flux detected by Rosetta.
Damn captcha thing. I’ll try again!
Found my original post: https://blogs.esa.int/rosetta/2015/06/02/ultraviolet-study-reveals-surprises-in-comet-coma/#comment-471429
The paper I was referring to was: https://science.sciencemag.org/content/347/6220/aaa0571.short
And the CME event is here: https://spaceweather.com/archive.php?view=1&day=13&month=09&year=2014
OK, I managed to get my hands on the paper: ‘Space Weather at Comet 67P/Churyumov–Gerasimenko Before its Perihelion’
https://link.springer.com/article/10.1007/s11038-015-9479-5
Generally speaking it is just about the predictive capabilities of the modelling they use, and how it is borne out by the detections at 67P by the RPC instruments.
From the conclusions (that are relevant to comets) we have:
> Solar activity on 1 September and 9–10 September 2014 produced responses at comet 67P/C–G when it was located at ~3.7 AU.
> The predictions of these models of the arrival at Rosetta/Comet 67P/C–G of three CME related disturbances corresponded satisfactorily with strong signatures observed in MAG and IES data, thereby providing confidence that the signatures recorded aboard the spacecraft were solar related and traceable to particular events.
> Photon-stimulated desorption and impact vaporization are deduced not to have been important in the sputtering process at the comet when it was located at ~3.5 AU. At
locations closer to perihelion, despite enhanced shielding of the nucleus from solar wind flux, energetic particles associated with significant solar activity can be expected
to stimulate sputtering.
The events the paper refers to occurred at the Sun on 01/09/14 & 9-10/09/14.
It should be noted that the sputtered species detected by Rosetta are infinitesimal in comparison to the number of gaseous molecules seen: https://www.aanda.org/articles/aa/full_html/2015/11/aa25980-15/aa25980-15.html
western limb, by the way. My mistake in the conventional terminology.
Hi OriginalJohn. Ianw16 has a reference to a future book containing solar flare effects. Indeed hits like that one are able to trespass…
https://blogs.esa.int/rosetta/2016/01/28/navcam-archive-update/#comment-598729
There is an apparent dimensionality constant on the zigzag of Imhotep periphery. Same as body terraces. Lower right of
https://planetgate.mps.mpg.de/Image_of_the_Day/public/NAC_2015-12-30T08.29.42.615Z_ID30_1397549100_F22.jpg
As in the ‘circular features’ at Imhotep, also some material structurally collapsed -or sank- at lower side of this shot.
Boulders’ size distribution seems highly related to layer patterns. Could them be ‘artisan’ [extrusion, molding, etc.] made at the site? Not only accreted?
Re Logan ‘extrusion,moulding etc’
This picture has so many unusual features, its hard to rule out almost anything.
Also how would try to explain the scene with a catch all of ‘sublimation’?
Its easy to think there is extrusion, some of the features here, we have seen before and extrusion or cast was a first thought even though there was less detail.
Geology, birth and development to this stage of the comet still seems a complete mystery.
Regards
@Dave,
If you live somewhere cold enough, build a snowman; watch how it melts over time.
And, yes, certain things can be ruled out due to a total lack of evidence that we should see were they actually happening.
Re Ian16 – Snowmen
I ski every year Ian, but have nevery seen any glacier or snow man look like this picture. Also I have climbed in the Alps and in Nepal
We seem to have different materials that dont subliment, they seem to be left behind. (or do they just ouse out?)
We have debris fallen off clifts which we see every where on earth, but that small part of the comet appears to have debris that has moved horozontally across the floor, presumeably from the jets.
We can see caves or pits that seem to have been the source of the jets, but he ratio of diam to depth looks odd especially the parrallel walls if we are going to conclude that the pits are caused by sublimation.
Of course there must be sublimation occurring, in fact there is good evidence where a thin surface layer of ice dissapears in the day and reforms at night.
However just look at the structures in this photograph there is much more to explain that even the simple example i have stated.
There is still a lot of explantion required to even get close to what is happening.
look at some of Logans coment, they point out other issues
But at least the Snowman is seasonal and worth a smile
happy New Year
As for ‘slab’ displacing visual clues’ arguments, just take a look at the front stage of
https://planetgate.mps.mpg.de:8114/Image_of_the_Day/public/OSIRIS_IofD_2015-12-22.html
Includes an apparent cut of a longitudinal impact. Low right. And an exposed chamber to the Low left.
Ducky exhibits a significant amount of their guts.
@Dave
“Of course there must be sublimation occurring, in fact there is good evidence where a thin surface layer of ice dissapears in the day and reforms at night.”
And we also know that that ice comes from subsurface: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/85998, which followed on from: https://www.aanda.org/articles/aa/full_html/2015/11/aa26181-15/aa26181-15.html.
To add to the solid ice that was excavated from Tempel 1, the ice entrained from the jets at Hartley2 and that seen after the outburst at 17P Holmes, then I’d say that is now pretty much a given. The exact mechanisms of how the surface slumps etc may provide interesting work for someone, but the ‘why’ is now very well evidenced.
Dave.
I’ve also climbed in the Alps, Himalaya and Andes; but you need to be very, very careful about drawing any analogies between what you see on earth and on 67P. It will often be highly misleading.
Low altitude Earth is a roughly one bar, one G (10m/s^2), 300 odd K environment.
By moving to high altitude, you get say half a bar (really high, 6000m ish), almost no change in G, but you do get the temperature below 274K, and water is frozen.
But the pressure and gravitational field on 67P remain orders of magnitude lower than on high-altitude climbers earth. This utterly changes the way things behave. Gas flow becomes diffusive, not viscous, structures which would collapse under their own weight are stable, etc etc.
When looking at 67P you need to ‘turn off’ virtually everything guided by experience and common sense, which were developed in that earth environment. You need to revert to the basic physics.
That is a common mistake here.
Logan (and Dave)
Regarding your linked, full size picture.
The duck is upside-down in this picture so the bottom-right zig zags are the sharp border between Seth and Anubis.
This photo shows exactly one side of the four sides of the diamond-shaped body. I would say the stretched diamond shape because stretch predicts such a perfectly symmetrical, stretched shape with the rotation plane running down its long axis.
I think the reason this looks so roughed up is because this entire area lost a slab. That’s in keeping with the way in which slabs would be likely to be lost once the diamond had stretched enough to be a discernible diamond. It would be one whole slab sliding off one of the four straight sides. And it would slide away due to spin-up. This is why all the edges and corners are so squared off. The slab broke cleanly from exactly one diamond side and the break enhanced the edges of that diamond side still further because it cut across any slightly curved edges that were originally curving round to Seth and Imhotep. Imhotep is round the corner at top-left.
It’s the same with Aten. It’s length is exactly one side of the stretched diamond. I think it’s a lost slab too. However, although Aten is the same length as this slab (due to it being one whole side and the diamond sides being almost exactly equal) it’s narrower. It doesn’t look as if it could have slid along and out of that deep trough. I’m going to address that on the stretch blog soon.
There are two gill-type features, the large dark ones and the small illuminated ones above-left of the large ones (below-right in upright duck mode). I’m not sure which ones you refer to. The Massironi et al paper identified the large, dark ones as exposed onion layers. I’d agree and say they are perhaps three or four layers down because the missing slab was three or four layers thick. I’d also say they have delaminated or ridden over each other during stretch as they were pulled towards the top-right i.e. towards Apis at the diamond tip (the flat section at top-right).
You can just about see lines or shallow ridges running from each ridden-up layer to Logan’s three zig zags, slightly more evident in other photos, though. I’ve already matched each of the three zig zags as delaminating from each other. That’s why they look so uncannily similar. I then noticed that they were linked to the large gills, showing that those onion layers too had delaminated in the stretch. So the reason the zig zags are so consistent in their shape is because they used to be one single feature that’s since delaminated along the long axis stretch vector towards Apis. They aren’t just matched along this edge but face-to-face in the shadowed area and their delamination tensile vector runs straight through Apis.
Would like to suggest to Cooper&Marco a slight variation of Stretch: Something ‘a la’ plaque tectonics. ‘Slab’ tectonics.
The advantage would be of the energy budget kind.
‘Slab’ tectonics require thermodynamics only at the surfaces in between slabs and not a global ‘mantle’ thermodynamics.
Logan
We stretch proponents reckon the crust was sliding around quite a bit just before the head sheared. As Marco says, it would’ve stopped sliding (almost) immediately as all the tensile forces moved to the stretching neck and the rotation rate slowed accordingly.
The last four stretch blog posts are all concerned with this sliding and there will be at least five more on the subject. The number of posts reflects the fact that almost nowhere on the comet escaped sliding, whether sliding away to escape (the slabs) sliding en masse to new positions (Ash) or delaminating (Seth/Anubis border).
Regarding the thermodynamics energy budget. If the crust really were being pushed about by slab tectonics then yes, it’s easier if it’s all happening near the surface and not a “global mantle thermodynamics” as you say. However, all the crust sliding signatures are radial, away from the north pole. And early indications suggest it’s radial from the south pole too but there’s a lack of good photos at the moment. So I don’t think the crust could be sliding about in such an organised manner due to thermodynamics. The radial force vectors strongly suggest spin-up.
So if several slabs escaped due to the centrifugal forces of a spin-up to a 2-hour rotation period there should be enough energy available for mere sliding. That’s because those slabs that escaped had to slide off in order to escape, if only for a few metres of tangential travel before detaching. They were at the extremities or nearer the extremities and had the energy to slide and escape. So it stands to reason that areas of crust at a lower radius of rotation would have the energy to slide but not escape. In fact, it would be puzzling if we didn’t see these signatures of a gradation in radial forces allowing escape at the extremities and mere sliding nearer the poles. And that is what we see.
“…However, all the crust sliding signatures are radial, away from the north pole”.
Your narrative is that spinning at the time of the ‘slabbing away’ was the same of today.
Wouldn’t be probable that the ‘slabbing away’ and all the latter activity would have changed that kinetic scenario?
Logan
I annotated your linked picture with the zig zags to show what I mean in my comment about it. It’s a page accessible in the menu bar on the stretch blog.
Logan
Regarding the ‘slabbing away’ changing the kinetic scenario, it did. But the rotation plane didn’t change very much and the spin rate change is largely irrelevant. Here’s my reasoning.
The hypothesised sliding of the crust and slabs escaping would have been dictated by the spin rate and rotation plane (equator) orientation before head shear and just after head shear. That’s according to stretch theory.
You’re right, the speed and orientation of the spin could have changed and indeed did change since then but that doesn’t matter because stretch theory is looking at the signatures imprinted during the period of fast spin and a particular rotation plane orientation before head shear. The paleo rotation plane is betrayed by 11 of those stretch signatures aligned along the long axis of the comet.
The rotation plane has changed by about 20°. The present day plane is off the paleo plane by that much. It’s precessed anticlockwise looking down on the head. It’s interesting to note that both old and new planes go through the long axis and the reason for this is that the rotation plane precessed about the long axis during stretch, along with the head precession of circa 15°. Slabbing away probably had some influence too.
Regarding the change in spin rate, conservation of angular momentum means the comet had to slow as the two lobes drifted apart after shear. My calculations say that a 2- to 3-hour rotation period was needed for slabs to escape and that AM conservation would mean it slowed to a 5.75-hour period (for the 2-hour initial spin up) as it stretched all the way to its current shape. Current spin rate is 12.4 hours.
The current spin rate hasn’t caused any of the sliding signatures that I’ve suggested. Or at least it would be very hard pushed to do so. As for the current rotation plane, it probably had some influence as the neck was stretching in the early stages when the spin was still fast and and the rotation plane precessing about the long axis towards its current position. But the paleo rotation plane would’ve held sway during all the slab escape and crust sliding prior to head shear.
The extent to which the current plane (and north pole) had an influence would have been betrayed by crust sliding away from the present-day north pole or a point just below it on the body. That’s because the pole would’ve crept up the body from its paleo pole position to current position during head stretch. Crust would have been sliding away from it as it crept up. The radial sliding force vector causing the slide would have diminished as the spin slowed. These radial signatures are abundant around the current north pole. But I’d guess they are a small ‘correction’ to the almost identical radial signatures induced by the paleo pole and which run all the way to Apis, Aten and the bottom end of Ash.
So the kinetics did change but that is predicted by stretch theory. A 3-hour rotation would mean an even slower resultant spin period after stretch (about 8.5 hours from memory). It wouldn’t involve much more spin-down after that to get it to the 12.7 hours that 67P had when first measured. From what I can tell, a 2-hour initial spin-up is nearer the mark but possibly more than needed and 3 hours is a bit lax, possibly not enough.
I do like your 3hr rotation for certain kinetic scenarios where relevant necks [like this one] are traversed by polar axis.
But would love to see some Scientific modeling about it, before inverting commitment to the idea.
Logan
I’ve done some calculations before in Rosetta blog comments. They are linked below. This could be considered as a single model run with a single set of inputs. It focusses more on the two-hour spin-up scenario. 3 hours is nearer the optimistic end of the envelope when considering getting the head to lift off (but not for the hypothesised slab ejection from Imhotep and Hatmehit.
The main uncertainty is the bilobed field. The inputs are quite conservative, implying a maximum spin-up necessary for all the stretch theory outcomes to happen as stated in the stretch blog.
https://blogs.esa.int/rosetta/2015/09/28/how-rosettas-comet-got-its-shape/#comment-553840
Then, four comments below this one I address the issue of the tensile strength in the neck potentially stopping or attenuating the stretch. Excerpt from that comment:
“As for the question of the neck stopping all this from happening, I’ve mentioned the low tensile stress of the neck material before in comparison with more modest spin-ups. For the neck, it’s 10-20pa (Thomas et al 2015). The highest estimate for the crust is 40pa.
I calculated the negative g force on the shear line to be 273 pa at the time of shear. Inputs: r= 1095m; T=2.033 hours; head lobe radius at shear plane 1.25km; head lobe mass 2.5E12 kg.
The 20 pa sapping of the upward tensile force by the neck is 20/273 of the whole, which is 7.5%. So the upward force that’s left for lifting the head is 92.5% of the amount used in the last comment. And due to linearity between terms, the negative g acceleration is 92.5% as well.
This hardly affects the scenario in the last comment and even with a 40pa neck resistance it would be a comparable output- the head lobe would rise to about the same place, dragging up the neck with it.”
/////end of quote from comment.
This weak, stretching neck scenario implies the pebble pile theory for the comet’s core, either the 3-metre dinosaur eggs that are seen on 67P or the “marbles” that were predicted by Carey Lisse in models. This link quotes Holger Sierks of OSIRIS talking about the dinosaur eggs and Lisse referring to the marbles.
https://news.sciencemag.org/space/2014/12/dinosaur-eggs-spotted-rosetta-s-comet
This would explain the low tensile strength of the neck if it’s loosely sintered pebbles making it a ductile core.
That Dark Mica from Eastern Ontario is a better model of what we have seen in more than a year,
Than any ‘accretion’ model presented until now…
[On declaring this, suddenly recovered my 3D sight…]
Another view of the zigzag (stair) at the bottom of
https://planetgate.mps.mpg.de:8114/Image_of_the_Day/public/OSIRIS_IofD_2015-12-13.html
Logan
This view is of the south pole. The zig zags you mentioned are over the horizon (only just though). They’re at the top, just beyond that shallow dip on the horizon. The Anubis/Atum area in this post’s picture is the area to the left. The darker patch at the far end is the lumpy onion layers and the small dark patch below that is the gills.
Thanks for the orientation, Cooper 🙂 Always is of help to me.
Another crystallization related:
https://upload.wikimedia.org/wikipedia/commons/1/1d/Feldspar-Group-291254.jpg
Il cristallo delaminato:
https://imagearchives.esac.esa.int/picture.php?/9914/category/66
https://imagearchives.esac.esa.int/picture.php?/9914/category/66
ROS_CAM1_20141123T174334_P.png
https://imagearchives.esac.esa.int/picture.php?/9885/category/66
ROS_CAM1_20141122T170002_P.png
Thinking along the lines of a conglomerate or better a breccia with a matrix softer (regarding sublimation and other erosive processes) than the clasts, of course made of entirely different material than conglomerates/breccias on Earth, would probably come closer to the actual processes:
https://en.wikipedia.org/wiki/File:Conglomerate_Death_Valley_NP.jpg
https://en.wikipedia.org/wiki/Breccia#/media/File:DebrisFlowDepositRestingSpringsPass.JPG
Related would be an interpretation as an outcrop:
https://en.wikipedia.org/wiki/Outcrop#/media/File:San_Carlos_Water,_Falkland_Islands.jpg
But comparing Earth geology with cometary geology is always a little questionable.
Essentially you have accretion and erosion/sublimation, plus impacts, only remotely similar to sedimentation and erosion/weathering on Earth.
Analogs to extrusions caused by gas pressure in the subsurface would probably either burst in a brittle way, or be barely visible.
Logan – matrix of boulders
I agree,
happy New year
Was about to say that doesn’t ‘feel’ like that, Gerald. But that Mezquite Springs link is very compelling 🙂
Hi, Dave 🙂 “…Its easy to think there is extrusion [or cast]..”. Indeed Dave. At this great shot there is kind of patches where a ‘matrix’ of boulders matches the matrix of layers.
There is more to the ‘gills trio’. Up and down. Could they be part of a former single crystallization?
Imhotep basin continues here. Of course, following gravito-spheroid.
“Rosetta’s view of Comet 67P/C-G on New Year’s Eve”.
Happy New Years, everyone. Was wondering who might get the posting ball rolling, looks like award goes to logan, with originaljohn a close second. And Harvey and Gerald are back, as well as ian. Nice to see that strong interest in the Rosetta mission continues.
Now, while this isn’t directly related to this article’s pictures, it is related to cosmology, and I was wondering what our resident scientist posters would have to say about it. This guy is throwing down a pretty big gauntlet. Article is “Did This Scientist Just Discover How the Universe Works?” Link at https://www.activistpost.com/2016/01/did-this-scientist-just-discover-how-the-universe-works.html
I’d say, it’s a mix of actual physics, like Planck units (https://en.wikipedia.org/wiki/Planck_units) , with complete nonsense.
The understanding of the author appears to end somewhere near results of Special Relativity, like E=mc².
So he includes the energy-equivalent of Earth into his musings. But the “ether stuff” is mainly nonsense, except that there is a relation to the Planck mass.
It’s true, that there is a problem with vacuum energy as derived from quantum theory in a straightforward way.
But I’ve seen much better suggestions to solve this problem than the attempt of the referenced article.
An explanation of gravity on a more basic level would need to comprise the Einstein field equations, or at least the measured results consistent with these equations:
https://en.wikipedia.org/wiki/Einstein_field_equations
That’s completely missing in the article. The author appears to be ignorant of these equations, as the statement “The question of gravity, relativity, magnetism, and, indeed, energy itself becomes answerable.” shows.
The field equations are kind of a generalized law of conservation of energy. The author seems to lack understanding gravity on the level of General Relativity. Hence understanding of gravity beyond that level doesn’t appear likely.
… the referenced and cited article of Marianne Freiberger looks good, as far as I see:
https://plus.maths.org/content/problems-gravity
… “The mainstream physics community will no doubt immediately scoff at Fernandes’ claims.”
Indeed, and not surprising.
His calculations seem to be self-consistent, his approach funny, but unphysical. Newton’s law of gravity and Coulomb’s law are both inverse square laws. F. Fernandes concludes, that this justifies equalizing them. But that’s wrong and too superficial, since other aspects of gravity and electromagnetism don’t match that easily.
Retry, the year’s first Capta problem!
It’s a mish mash of real physics and pure nonsense.
Any time you see ‘aether’, stop reading. The writer seems to have overlooked Michelson and Morely, 1887.
Harvey,
I fear, it’s not quite as simple, since there exist modern versions of ether theories. See e.g.:
https://en.wikipedia.org/wiki/Aether_theories#Conjectures_and_proposals
https://www.amazon.de/Ether-Space-Time-Cosmology-Volume-relativity/dp/1873694105
https://arxiv.org/ftp/physics/papers/0501/0501060.pdf
OK, perhaps I over simplified.
But I note that Kholmetskii and Duffy have almost nothing but self citations; not exactly won wide acceptance.
The details are into territory where I’d have to say ‘sorry, not competent to form a view.’
Difficult subject to search; you get swamped by inflammable, intoxicating organic chemistry 🙂
Ah yes Harvey let’s not have barmy stuff like aether that cannot be interacted with. We have enough already with dark matter, dark energy, black holes, densely packed neutron material and the Oort cloud,
The Universe is, I’m glad to say, stuffed full of ‘barmy’ things. There are barmy things that are consistent with observation, consistent with our understanding of physics – but *always* up for revision if we find contradictory data, a mistake, whatever.
Nothing says the Universe has to be ‘reasonable’, simple, whatever. It is what it is.
Then there are barmy things which are just, well, barmy. They don’t agree with observation, they don’t agree with well proven physics.
The link is so appallingly bad and riddled with errors.
There are experiments that rule out the existence of both stationary ether and ether attached to moving bodies such as the Michelson-Morely, Kennedy-Thorndike, and Trouton-Noble tests. Then there are astronomical observations such as stellar aberration that rule out ether attached to moving bodies.
Strange how the evidence or in this case the lack of it is ignored.
Here are some of the errors.
“It has been long known that Einstein’s theory of Relativity (E=mc^2) only works on one level. Its does not work however on extremely micro or extremely macro levels. ”
E=mc^2 is an outcome of the Special theory of Relativity not the General theory.
While General Relativity is a scale dependant theory that is incompatible with Quantum Mechanics , Special Relativity is applied to Quantum Mechanics to form the basis for Quantum Field theories which applies to the “extremely micro”.
As a stand alone theory the Special Theory is applicable to the “extremely macro”.
“Gravitation energy or force is believed to be weak and nowhere in magnitude to the electric force. I assumed the energy of gravity to be equal to that of the electric energy.
Energy calculated by Newton’s gravitation equation is the same as energy calculated by Coulomb’s electric equation.
E= Gmm/R = kee/R”.
The calculation methods might be the same but it doesn’t imply that
E= Gmm/R = kee/R.
Gravitational and electric force fields are examples of conservative force fields and can be expressed in terms of potentials E=Gmm/R and E=kee/R respectively.
A particle moving from one potential to another in a field is either doing work, or the work is being done by the field on the particle.
The equation E=Gmm/R= kee/R is clearly wrong for neutral particles since no work is performed in an electric field, despite work being done by or performed in a gravitational field.
“The force of gravity of Newton’s equation is assumed to equal the centripetal force.
F= Gmm/R^2 = mc^2/R”
F=mv^2/R is the centripetal force acting on an object of mass m moving in an orbit with a tangential velocity v.
In the above equation v=c , the speed of light IS IMPOSSIBLE as objects with non zero mass cannot travel at the speed of light.
Hence the equation F= Gmm/R^2 = mc^2/R is nonsense.
Then there is the case of gravity acting along the direction of the centripetal force for objects in orbit.
What happens if the object is in free fall moving in a rectilinear motion in a gravitational field?
Clearly centripetal forces don’t apply here and the force of gravity therefore is not equal to the centripetal force.
There are also misconceptions about the role of General Relativity in Cosmology.
General Relativity doesn’t “demand” the Universe has to expand, contract, oscillate be static or contain a certain amount of mass.
General Relativity is the gravitational theory applied to the Cosmological model.
The model itself determines whether the Universe expands etc.
For example there is the non physical Godel Universe model where General Relativity is applied to a non expanding but rotating Universe.
https://en.wikipedia.org/wiki/G%C3%B6del_metric#Cosmological_interpretation.
Sorry to disappoint you SS but there will be no paradigm change occurring here.
Thanks for the replies, I thought it was an interesting article and wanted to see what others thought of it. I thought it was a good illustration of some of the problems that are trying to be answered about the universe, though his proposals to me seemed highly dubious, not because of a detailed understanding of the science, but I’m just highly dubious about the existence of dark energy, and all the other dark whatevers, and any approach that tries to explain such speculations. Anyway, he seems to be trying to explain too much in an all inclusive, neat and tidy was, and as you say, this is a mix of actual physics with nonsense, but there seem to be so many highly theoretical constructs in cosmology that seem to often conflict in one way or another with each other and with observations, I often wonder how far the nonsense actually extends, and whether much of anything can really be asserted with much degree of certainty.
Sovereign Slave,
the Planck papers discuss many of those questions in very detail. But I fear, that most of these papers are almost impossible to understand for laymen.
https://www.ias.u-psud.fr/douspis/Site/Planck_papers_2013.html
and
https://www.cosmos.esa.int/web/planck/publications
The word “dark” is used for phenomena, whose existence are inferred exclusively from gravity.
There are two fundamental approaches to overcome the gap in the theoretical models: One is postulating a modified theory of gravity, like MOND theories, the other option is postuating the presence of “dark” matter and “dark” energy.
The majority of cosmologists (and particle physicists) prefers the “dark” postulate.
Systematic observational errors as an explanation are assessed as very unlikely.
As long as there are no immediate ways to observe the “dark” phenomena, all you can do is fitting loads of theoretical models, and refine those which match best.
Particle physicists are hunting for WIMPs as a model of dark matter:
https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles
ESA’s EUCLID mission is intended to investigate possible structure of “dark” energy:
https://sci.esa.int/euclid/
Here two links to the MOND approach:
https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics
https://arxiv.org/abs/1404.7661
“The word “dark” is used for phenomena, whose existence are inferred exclusively from gravity.”
Gerald, that’s a great statement, though I think it’s safe to say that it would be more accurate to say “theoretical phenomena.”
This statement, “Systematic observational errors as an explanation are assessed as very unlikely,” seems a bit self serving though. First there’s data and observation, then comes the process of making sense of it all. A theory brings it all together, but here you have theories just for the sake of saving other theories, or “gaps in the theoretical models.” As you point out, there is no way to observe these theoretical phenomena, or directly measure them, they are simply a necessary intellectual construct to save generally accepted theories that don’t really add up. In cards, it’s the equivalent of jokers, except with cards you’re limited to just two, in cosmology, it seems to be as many as you need. Regardless, I think it would be an interesting start to assume that the rest of the galaxy and universe operates much like (or identically) to how our own solar system does, and construct a cosmology on that assumption. Would demand a huge reworking of theories of course, because as it stands, it’s pretty clear that the underlying assumption of modern cosmology is that much of the universe is vastly different than our own solar system, and does not behave according to known physical laws that operate here. Anyway, this seems like a dangerous assumption, and one that obviously leads to all kinds of wild speculations with countless jokers, so to speak.
Sovereign Slave,
it’s the other way round: Assuming the rest of the universe working exclusively like what we know about our solar system leaves open the gaps on the large scale.
Those gaps are now filled in with “dark” phenomena, to give those discrepancies a name.
The actual physical meaning is still speculation.
Usual captcha issues.
SS,
I think you should take the trouble in gaining knowledge of what cosmology really is instead of making opinion based comments on the subject.
A deep understanding requires a knowledge of the mathematics of both the cosmological model and general relativity but elementary texts should give an insight into what cosmology is about and how cosmologists arrive at their conclusions.
Making sense of observations and experiments is only part of the story.
A theory should also make testable predictions.
The Big Bang theory successfully predicted the existence of a cosmic radiation background, variations in the background, the abundance of hydrogen and helium in the Universe to name a few.
As I mentioned in a previous post dark matter and dark energy are measurable effects, they are not intellectual constructs to save the theory.
This misconception seems to stem over confusion about cause and effect.
If a cause is not known then the effect is somehow “made up”.
Yet in everyday life we see the effects of gravity despite there being no satisfactory theory on its cause. We don’t summarily dismiss the effects of gravity because we don’t know its cause.
Its ironic you claim we should model cosmology on how our solar system works, yet dark matter is the outcome of modelling the rotation curves of spiral galaxies like our solar system.
In this case the stars in the outer parts of a spiral galaxy should exist in Keplerian orbits around the galactic centre. The orbital speed should decrease with increasing distance like the planetary orbits around our Sun.
Yet observations reveals this is not the case.
One way of explaining this observation is due to the effects of dark matter.
There is a theoretical “justification” for dark matter.
Newtonian gravity is a linear theory that can result in theoretical Keplerian orbits being perturbed due to gravitational effects by other bodies.
In the mid 19th century there was a “dark matter problem” involving the orbital perturbation of Uranus by an unknown mass.
That unknown mass was Neptune whose orbit was predicted and subsequently verified.
The physical laws are the same for both the solar system and the Universe.
We don’t observe the effects of dark energy in gravitationally bound systems such our solar system, galaxy or even galaxy clusters because the effect is extremely small. Also the general effects of expansion becomes apparent at cosmological scales as is shown by the value of Hubble’s constant.
Gerald, you have just very effectively restated my point – it WOULD leave gaps in knowledge and understanding on a large scale, gaps that are already there anyway. Simply filling the gaps with jokers and labels provides the false comfort of pretending to know something that is not understood or known at all, and I think highlights fundamental and pervasive flaws in our understanding of both the universe and our own solar system.
On following Sjastro line of thought:
How many centuries was ‘atom’ just a mind construct?
Right Logan, but then again, how many countless mind constructs have been wrong? Sure, modeling and math and imagination are all great and lead to advances, but it’s fascinating to me how much “universal” faith and adherence is put into these highly theoretical theories as actually being true, and if you deign to question them, your just considered dumb and ignorant and misguided, as a non-scientist or scientist.
The point here, Sovereign Slave, agreeing with you. is that all models start tentatively, temporally, and our confidence in them should be of the same class.
…But so many times We have to stand on balancing rocks, in order to arrive to a little more solid foundations.
ROSETTA herself is a balancing rock, playing against nemesis every day.
The article is pure junk.
What was the point of it?
It highlights the problems encountered in modern cosmology which is fair enough at small and large scales.
One would have expected the article to address these scale issues with this quantized ether theory.
The facts are that neither end of the spectrum is addressed.
At small scales where do the weak and strong (nuclear) forces fit into the picture?
How does the theory address the observed acceleration of the Universe at large scales as measured by the light curves in type 1A supernovae in distant galaxies?
It appears the problems conveniently disappear which is typical of crank theories like the EU.
Incidentally his calculations for the Earth’s ether mass are absolute nonsense.
He claims the Earth’s either is contained within its radius and uses mass is proportional to radius in his calculations.
Unfortunately we don’t live in a one dimensional Universe and mass is contained within a volume. Hence mass is proportional to (radius)^3 and should have been used in the calculations instead.
His calculation for the Earth’s ether mass is out by the proverbial light years.
As a result his calculation of g is a fluke.
What are the theoretical constructs in cosmology that conflict with each other?
If you believe that dark matter and dark energy are made up to simply get the maths
right you are wrong as their effects are very real and measurable.
As to what dark matter and dark energy actually are takes it out of the field of cosmology and into particle physics.
Hi SovereignSlave. Physicists are seriously working at restating their scientific methods. You are on the point, on keeping an eye on it 🙂
Like to think Our resident Scientists have the point over the view of this paper’s authors.
Tried to post on iPhone, don’t think it took, so try again. Was just wanting to know if you have any specific articles or resources about this that you could share.
Time to retake the first ‘breath’ of the morning. The issue was chewed at the blog some months ago, and perceived plausible down to a single digit meter process.
By now OSIRIS close-up shots have made clear porosity is relevant at many macro scales, so that first morning ‘breath’ can go deeper down under, as heat transfer phenomena 😉
[The bigger the porosity, the longer the ‘free path’ of energy containing sublimated molecules].
Ducky inhale at surface one time at dawn, exhale one time at dusk. Eventually reaching an equilibrium sublimation/deposition line during day [and night]. Who proposed this first? Robin?
That first ‘breath’ of the morning is an uneven mechanism and could contribute energy to outbursts, and ultimately to progressive ‘necking’.
[Not yet discarding field energy transfer :)].
Do our Earth caves breath more at Equator, than progressively going to poles?
Inhaling -in molecular flow parlance- would mean taking in more molecules, than taking out, at the relevant [sub-]surface line.
Of note that the energy budget contributed by this mechanism was irrelevant to Shoemaker Levy disassembling|catastrophic-bursting.
Of note that documented tensile strength is deducted for surface material only. If remembering correctly ‘overhangs’ calculated.
Overhangs are related to coma return blanket dynamics, among another processes.
Coraline… Insist that is a good name 😉
Cooper&Marco:
You can explain totally on ‘slab’ arguments only.
Crystals are repetitive and repetitively match.
The ‘twisting’ in between head and body is more than acceptable at this scale.
No plasticity required. Even if there are localized clues of it.
Harvey and Gerald could be right. 67P could be a single a object, also.
Hi Logan,
So cryptic are you:-)
The surface of the comet makes sense to us now for all regions with the stretch paradigm, with new, high resolution images giving us more pieces to work with that keep fitting in with the paradigm, while refining the narrative, especially in regards to the delamination of outside layers with centrifugal stresses pre-fracture. These delaminations do hark somewhat to a form of tectonics, but are frozen in time since the stress was completely transferred to the neck on fracture.
The problem is that the stretch narrative goes against several aspects of conventional cometary thought.
The time for fiddling around with a narrative that explains little of the evidence should be over, and we should be (again) looking to see if mission scientists can address stretch at least as an avenue of research.
A couple of ideas would be to make accurate before and after neck length measurements and also at some of the proposed fracture areas, which are interesting in their own right and a lack of “erasive” erosion would point to matches being faithful.
Regarding Marco’s point about mission scientists revisiting stretch.
During LPSC15 there was a Twitter exchange on Emily Lakdawalla’s thread where someone said there would be another Rosetta mission after this one. That would be done by outside scientists using the (by then) freely available archived data. I found that quite heartening but now I have my reservations. The data taken during the mission isn’t all the data there possibly can be on the comet. It’s taken with certain assumptions, working hypotheses and interests in mind. Not to mention the restrictions of competing priorities such as finding Philae.
If stretch isn’t even on the table as a working hypothesis then the data collection that might prove or disprove it won’t be carried out. Or if it is carried out it will be done by chance during general data collection for other reasons and will be incomplete.
So seeing as we’re now on the last leg of the mission I would earnestly request that the Rosetta teams take whatever data they can with stretch in mind. It can be proved or disproved later.
Most of the work would involve the highest possible resolution data along the head rim and shear line on the body. Also along the shear lines of matching layers that peeled away from each other prior to head shear.
It would involve careful scrutiny of the lump sticking out of Anuket just below the Alexander Gate as well as the right hand pillar of the gate (looking from below) which the lump matches to. It would involve analysing the four zig zag lines running down Anuket, one of which includes the lump. These lines link head matches to body matches. They should be compositionally consistent along their lengths or at least exhibit a subtle, consistent change along their lengths. They would also contrast with the Anuket matrix in which they’re set.
A stretch theory-based analysis would also mean trying to determine the composition of the large, flat part of Serqet, especially its right hand end, to see if there were compositional similarities between it and the place it originally sat, namely, under that sudden kink down in the head rim at Anuket (because it broke through the onion layer above it according to stretch theory).
Other investigations would centre on the slurry signatures that abound all around the shear line. These areas must surely exhibit similarities in their composition as well as their obviously similar morphology. A related study would involve analysis of the line of small scallops running round the second tier of the ‘cove’ on the head. Also, the fluted ends of the lines running straight up Hathor and arranged along the head rim at Bastet. These features are all related to slurry signatures and scouring on the body when the head lobe is reseated on the body.
Other areas of interest with stretch in mind would be the head rim at Serqet, which may be more porous than elsewhere, the cliffs of Aten.
And perhaps the most important thing to do would be a highly detailed analysis of the surface composition of Apis as compared with other surface areas of the comet. That’s because Apis is likely to be the only piece of pristine crust left on the comet with the whole of the rest of the surface having been reworked in recent ‘geological’ history. If we are looking for pristine cometary material from the dawn of time for Rosetta to decipher then Apis should be the most studied region on the comet.
I realise the whole comet is being analysed so all this data is being taken anyway but could it be taken at a higher resolution in these specific areas?
“…If stretch isn’t even on the table as a working hypothesis then the data collection that might prove or disprove it won’t be carried out.”
Why would it be over it? Not a singe euro assigned to it. Did it even exist at mission design?
This is a mission of an unprecedented openness.
Take the best fitting papers and data to enforce your argumentation, and be grateful to those Team members patient enough to drop by now and then, making some pre-release and out-reach chat.
As a foot note, there are Teams following carefully dimensional measures.
Hi Logan,
For the mission as a whole, the openness is unprecedented, but for the OSIRIS team, how can I say, the openness is precedented.
The explanation of the shape from the mission teams is like “Oh! It can’t be erosion, it must be contact binary! Wow” then “Contact Binary makes no sense at all, it IS erosion after all!”, then “All those other theories like EU etcetera are obvious failures to explain the shape”
Marco, this issue evolves so fast, take a look at the last H NAVCAM library, H ESAC 168, binary probability is quickly diminishing [never to be zero] 😉
Hi Logan,
You say the issue evolves fast. There is some “hysteresis” between the ideas of Contact Binary and Erosion. There is still that feeling that it is ok if one of these ideas becomes virtually disproven (as you say never to be a probability of zero) because the other is seen as an always viable alternative (also never to be a probability of zero)
The comfortable narrative required by this dichotomy is the certainty that it accreted at the dawn of the solar system, and that it is eroding now – I guess the metaphorical sound of the mission scientists scratching their heads rather than making further pronouncements is encouraging for my assertion that this dichotomy is absolutely false.
Combative only of comments and papers lettering statements akin to: “this is the only possible explanation to…”. I’m with slab model.
Seeing no direct attacks on your model [but your defending arguments].
There’s no point in raking over the past.
Logan
Raking over old coals might be more apt, except Marco isn’t really occupied with the CB theory episode. That’s because he knows you could rake all you like and never that one going. With angled onion layers in keeping with angles predicted by a herniating head lobe and a modelled impact scenario with 1/16th the specific KE of 67P’s ‘impact’, CB theory is very far from proven.
Marco is simply talking about the theory with the most evidence going for it. It’s all there on the stretch blog. Even for those who don’t accept stretch, the crust was sliding and delaminating all over the place- except always away from the poles. That alone is a huge clue.
Hi Cooper&Marco. “…a narrative that explains little…” And that says it all.
Taking very seriously your slab argumentation.
But not thinking of discarding any narrative. Not even the snowball classic. Could bet there are some snowballs around there.
Still not discard Galileo’s.
Crystals can act as antennae. Especially the porous kind.
Months ago Robin baptized the neck as a ‘trench’. In a stand for precise language.
This come to show its importance now: No matter how much the walls of the trench go further apart, they will still show matching clues. Simply because both walls exhibit the same crystalline patterns.
In the excitement of the idea forgot to tell: All of this is fiction. One script, among infinite possibilities.
If well neck erosion could be due to orbital mechanics, geometry dominate.
https://imagearchives.esac.esa.int/picture.php?/10103/category/66
ROS_CAM1_20141201T104502_P.png
https://imagearchives.esac.esa.int/picture.php?/10305/category/66
ROS_CAM1_20141213T172934_P.png
Two orders of magnitude below crystallization account for much less imperfections…
Lower part of
https://imagearchives.esac.esa.int/picture.php?/10189/category/66
ROS_CAM1_20141206T023934
We need also to walk the walk:
ROS_CAM1_20150805T173202
https://imagearchives.esac.esa.int/picture.php?/38604/category/168
ROS_CAM1_20150809T172442
https://imagearchives.esac.esa.int/picture.php?/38670/category/168
ROS_CAM1_20150813T200003
https://imagearchives.esac.esa.int/picture.php?/38737/category/168
ROS_CAM1_20150701T233301
https://imagearchives.esac.esa.int/picture.php?/38181/category/167
ROS_CAM1_20150707T033046
https://imagearchives.esac.esa.int/picture.php?/38240/category/167
ROS_CAM1_20150707T125909
https://imagearchives.esac.esa.int/picture.php?/38244/category/167
ROS_CAM1_20150709T054039
https://imagearchives.esac.esa.int/picture.php?/38283/category/167
ROS_CAM1_20150710T051003
https://imagearchives.esac.esa.int/picture.php?/38294/category/167
ROS_CAM1_20150710T183523
https://imagearchives.esac.esa.int/picture.php?/38301/category/167
ROS_CAM1_20150711T190820
https://imagearchives.esac.esa.int/picture.php?/38310/category/167
OS_CAM1_20150712T200002
https://imagearchives.esac.esa.int/picture.php?/38321/category/167
ROS_CAM1_20150713T212405
https://imagearchives.esac.esa.int/picture.php?/38333/category/167
ROS_CAM1_20150722T153621
https://imagearchives.esac.esa.int/picture.php?/38424/category/167
ROS_CAM1_20150819T073410
https://imagearchives.esac.esa.int/picture.php?/38823/category/168
ROS_CAM1_20150819T192742
https://imagearchives.esac.esa.int/picture.php?/38833/category/168
ROS_CAM1_20150819T230002
https://imagearchives.esac.esa.int/picture.php?/38836/category/168
ROS_CAM1_20150820T194502
https://imagearchives.esac.esa.int/picture.php?/38850/category/168
ROS_CAM1_20150821T074300
https://imagearchives.esac.esa.int/picture.php?/38860/category/168
Logan
Thanks, nice selection, especially (as they appear sequentially in your list) numbers 1,7,8,11 and 18.
The most spectacular matching is that of the flat, south pole sides of both head and body. It’s a match that holds up from all angles.
Some show the Aker to Bastet match very well: same width and similar surfaces and totally roughed-up areas either side of their common ‘vertical’ perimeters.
The triad of shapes that I mentioned recently is also visible at Maftet on the sharp corner between Maftet and the s pole. They are matched with a similar line of three shapes on the same sharp turn on the body directly below. That’s even at 160km distant. They have already been matched in great detail, close up, and also at medium distances from all angles.
The same goes for Aker-Bastet with mirrored matches from the body shear line to the underside of the head rim. These matches were done in fine detail in part 21 on the stretch blog. The three shapes were in part 17.
I wonder how many people went through all 18 of your linked photos? This sort of slow, methodical analysis of the *actual comet* that you and some others such as Bill Harris and Robin Sherman perform is barely evident in the comments. It’s the only way of divining the mechanisms for its totally bizarre morphology.
How in awe I am about the beauty of ESAC library 66!
Are Portals dual Crystalline Vertices?
Faces and vertices of a polyhedron, or more general of planar graphs, correspond to each other in the dual structure:
https://en.wikipedia.org/wiki/Dual_polyhedron
https://en.wikipedia.org/wiki/Dual_graph
Since many crystals are polyhedrons, this applies to crystals, as well.
A well-known example is pyrite. It occurs e.g. as cubes or as the dual of the cube, as octahedrons, but also in-between, besides pentagon-dodecahedrons. The duals of pentagon dodecahedrons, the icosahedrons are rare as pyrite crystals.
cube:
https://skywalker.cochise.edu/wellerr/crystals/isometric/cube-pyrite2.htm
octahedron:
https://skywalker.cochise.edu/wellerr/crystals/isometric/octahedron-pyrite1.htm
between cube and octahedron:
https://www.flickr.com/photos/usageology/11888861023/
pentagon dodecahedron (on the macroscopic level) :
https://www.minerals.net/Image/5/107/Pyrite.aspx
And a link to a site about crystals of – in my opinion – possibly the most advanced mathematical physicist of our time, with an image of a pyrite icosahedron:
https://math.ucr.edu/home/baez/golden.html
Indeed, Gerald. My thinking was reduced to the particular crystal carried into the conversation, Ontario Mica. Diverging to the general idea of dual polyhedrons (crystal matrices) gives a more rigorous focus to the issue.
More grateful of You starting to render this theme 🙂
… seems people have been thinking about this subject since the Neolithicum:
https://arxiv.org/pdf/math-ph/0303071v1.pdf
(Figure 1)
Gerald ‘Neolithicum’
Reminds me of my very first maths lesson at senior school more than 45 years ago.
I would not have ever thought I was ever going to see my favorate ( to pronounce anyway) Dodecahedron, produced in stone. Nice link
regards
What about seeing reproduced in the sky, Dave? 😉
/music_tag
Lucy in the sky, with diamonds.
Logan
Far out
Oops! Referring to Claudia&Angioletta’s Gates.
Warm effluvium meeting with colder one.. And erasing ice crystals in the process….
Another scenario is a ‘dark’ effluvium front staging a lighter one.
https://imagearchives.esac.esa.int/picture.php?/10379/category/66
ROS_CAM1_20141218T054334
ROS_CAM1_20141218T054334_P.png
Erosion caused by sublimation is ‘deconstructive’. Erosion caused by stress ‘wastes’ the material’s structure. Other forms of erosion apply.
“But, I don’t have more than a tentative answer yet. And it will probably be something I continue to work on the rest of my career.”
…
“The scientific method stresses a slow accumulation of knowledge, nuance, and doubt.”
…
A very good piece of Out-Reach, written by Brian Resnick, on the perennial tension between Science and Journalism.
https://www.vox.com/science-and-health/2016/1/22/10811320/journalists-social-science
“— but it it still frustrating sometimes for research of which we are probably proud to end up getting characterized and then ridiculed as the comment stream gets further and further from the original research and everybody tries to make a volatile ideological vessel out of it”.
John R. Hibbing, regent professor, University of Nebraska Lincoln
Every mind ‘sees’ trough their own cosmos of mythologies. To a scientist could still appear as plain wandering. To a mere mortal is the detachment of a former plain ignorance. Doesn’t matter if initial directions are random. Scientists shouldn’t feel offended by this apparent ‘noise’ around her or his beloved work [Rather should feel offended by the lack of ‘noise’, which means the work is of interest only to colleagues, at best] 😉
Order against Chaos. Our quotidian languages inherit the aesthetical preferences of Greeks and Latins.
But order is carried by its own daemons: Quietness, stillness, freezing, eternity.
Order is not always inherently good, and is shocking to see physical proof. Indeed is cause of mental refusal, of denial.
Understanding a cometary system requires a careful assessment of Entropy Theory.
On the issue of reversible, infinitely cyclic processes, an apparent necessary sub-product is a slowly progressive build up of order…
Know nothing about this field. As Gerald says: goes beyond the limits of this little skull, of this ephemeral life.
Let’s imagine a noise free, closed system. The build up of order advances to a point where no more transit of mass, energy or data happen.
This is fiction.