Thursday, March 17, 2016

Reblogged Imhotep Sliding post





67P/Churyumov-Gerasimenko. A Single Body That’s Been Stretched- Part 42

 THE IMHOTEP CRUST SLIDE- INITIAL OVERVIEW  


This photo shows the large-scale crust slide vectors at Imhotep. It shows the red slide to the left of the comet’s yellow short axis and the orange slide to the right of the axis. The red and orange slides involve a lower layer of crust, one ‘onion layer’ below the former surface onion layer layer. These header photos are reproduced further below, with their keys and a detailed explanation.

Photo 2 
 The same photo as above but with the predominantly up and down blue crust slides added. The blue slide involved mostly the top onion layer of crust. 
Photo 3 
The same photo as above but with the extra green slides added. The green slides were those that slid on further than the extent of the red and orange slides after riding on them and delaminating from them when they stopped. 
Photo 4 

The depression (blue dots), a site of outgassing and slurry effusion, along with the gravitational low point of Imhotep (green).
INTRODUCTION
The depression on Imhotep shows obvious signatures of catastrophic outgassing and slurry effusion and it straddles the paleo rotation plane (Part 26). The lowest point of the depression is plumb on the paleo rotation plane and is also at the intersection of the long and short axes of the diamond-shaped body. It’s in the middle of the lowest of the three flash-frozen slurry lakes in the depression. 
The depression’s location, right in the middle of the diamond, which according to stretch theory would be stretching along its long axis, means the depression is a prime candidate for being the focus of the initial crust-tearing event. The crust tore from this point before it slid across the base of the comet. The comet would be stretching due to spin-up via asymmetrical outgassing. The slide mechanics would be similar to the slides at Babi, Seth and the south pole (Parts 38-40 for Babi/Seth and Part 30 for the south pole).
Stretch theory strongly implies liquids under the crust, in the core. Conventional cometary theory doesn’t allow liquids due to modelled temperature and pressure scenarios. Although stretch theory implies slurry, it doesn’t depend on slurry for validation. The copious head-body matches throughout this blog are the validation. They prove that the head was once attached to the body and so, by definition, has stretched to its current position on a stretching neck. This simple proof led to evidence for the single body stretching before shearing, then evidence of the paleo rotation plane and on to crust sliding at Babi, Seth, Ma’at and the south pole. So crust slides at Imhotep are simply a continuation of the expected behaviour of this comet under spin-up and stretch. 
Slurry would be liquids (either water or hydrocarbons) mixed with refractory material like dust. Slurry signatures are to be found in abundance everywhere where stretch theory points to shearing, slab loss and crust sliding. It suggests that exposing the lower ‘onion’ layers releases liquids that were previously pent up under or between those layers. To be clear, the shearing, slab loss and crust sliding were all identified via matches in the previous 41 parts of this blog and only after they were established did the slurry signatures become apparent. The slurry signatures were therefore an independent corroboration of the matches. The same applies to Imhotep and the depression, except this time the penny finally dropped- I was able to find the last two pieces of slid crust by noticing the form they had left on the slurry and circles in the depression. 
A SCENARIO FOR IMHOTEP 
If you were to picture the most ideal crust-sliding scenario on the base of the comet, the pieces would slide away in pie shapes with their tips all kissing the central point of long- and short-axis intersection. 
Their initial detachment would cause a fissure to open up in that highly concentrated area of tearing. The initial fissure would be at dead centre of the diamond-shaped base because the stretching forces (predominantly along the long axis) would operate in tension either side of that central point just like a tug of war. If any crust was going to give way, it would be most likely to do so at the centre. That would be like the tug of war rope snapping in between the two teams rather than halfway along one team’s stretch where the tension in the rope is less. 
The initial fissure from the initial, central tear would become today’s lowest point. If the fissure was two onion layers deep, it would be very deep. And, if there were liquids in the interior, they would gush from the fissure due to sudden exposure to the vacuum. This would be similar to a boiler flash when a boiler is punctured. The formerly pressurised water flashes to vapour violently as the pressure drops but not necessarily all of it right away. Some liquid is carried off in the explosion so you have a mixture of gas and liquid being ejected. But all of the liquid vapourises as it’s carried away. The technical term is a BLEVE:
If, as in the case of the comet, the water is mixed with dust and general refractory material, it would be slurry by definition. When all the water did eventually evaporate away through the slurry due to the zero, vacuum pressure, it would leave behind the silty dust as a flash-frozen lake bed. If the lake was deep enough, some water might flash freeze at depth and perhaps gradually sublimate away over time, through the overlying layers and in the conventional manner.
The exiting of gas and slurry from the initial fissure would scour the feeder dyke wider and so deepen the fissure, which is why it would likely become the deepest point in the depression once the slide event was over. 
The slurry would well up and over the surface of the comet where it could but if the flow was too high for the width of the fissure to allow escape, it would also force its way under the loosened crust pieces that were on the verge of sliding away for good. It would follow weak spots to form collateral dykes under the crust until collateral, vertical fissures were found nearby. 
This would especially be the case if the depression had an upper, circular lid of crust and the pie-shaped pieces were actually a second layer of crust sitting under it. That is, the upper lid had loosened enough to allow a drastic drop in pressure underneath but while possibly floating on the emerging slurry it was forcing the flow further down to move laterally through the second fracture plane down.
The lid would eventually slide (or even float) away across the surface of the comet, pulled by a small arm of attached crust which was itself sliding due to stretch. This would expose the second layer down consisting of the notional pie shapes that were kissing at the middle of the depression and now free to pull further apart. The collateral fissures opening up close to the initial fissure would widen into noticeable cracks due to continuing stretch. They would reach perhaps 80-100 metres wide. This would allow the slurry to expel its gases at the base of the cracks, on exposure to the vacuum. The gas being expelled would be the formerly described liquid flashing to gas or BLEVEing. These wide cracks would leave a signature of their existence after the crust pieces had eventually slid away. It would be in the form of 100-metre-wide lines of flash-frozen slurry residue (the dust and refractory material). The lines would exhibit circles where gas was forced through the slurry. In fact there would be so many circles, some overlapping, that they would in effect be 100-metre-wide lines of circles:
Photo 5 
Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Furthermore, the areas where the crust had been sitting on the slurry, next to the cracks, would exhibit flat layers of flash-frozen slurry residue because the gases couldn’t escape- except that on closer inspection, you might see some smudged circles which would suggest that some lesser amount of gas was indeed being forced out and through the porous crust. These circles would be almost indiscernible due to the crust sliding away over the top of the slurry and smudging it. But it would slide away from the wide cracks, not over them, and therefore away from the undisturbed circles at the base of the cracks. The tracks of flash-frozen circles would be imprinted in the depression, betraying the puzzle-fit pattern of the slid crust. It would then just be a question of finding those shapes hundreds of metres away along the expected slide vectors as predicted by stretch theory. And then checking them by reversing the slide.
Since the entire process was liquid-driven, the resulting depression, though frozen and dry today, would have the uncanny appearance of a muddy water-hole. 
Everything we see in the depression and across Imhotep is consistent with this narrative. 
THE PHOTOS
The rest of this post is predominantly one long, narrative key to the header photos. It starts after the ‘key’ heading below. The first three header photos build up annotations so the third one has all the annotations from the first two. This third photo is reproduced before each of the key colour headings in the key so as to make it easier to scroll up (or down) and check the description against the photo. 
Contrary to other posts the references to up, down, left, right refer to those literal directions in the header photos.
The crust slide matches for the base of the comet are numerous and fairly complex. This post is an overview so no matches are proven. They will be proven in the most intricate detail in due course. The reason for an overview is because we need to see how the slide geometry is intimately related to the paleo rotation plane of the comet (which is the long axis of the diamond-shaped base) and to the mirror line of sliding symmetry (the short axis). In other words, the crust sliding is related to comet spin-up and stretch. 
Some Imhotep slide matches have already been documented, without any narrative. They’re in the dedicated Imhotep slide matches page which is accessible in the menu bar above. The matches there are just an ad hoc jumble at the moment and only a small proportion of the total. They appear to have no linking narrative. This overview post will flesh out the narrative. Subsequent posts will insert those ad hoc matches and others into that narrative. 
A hat-tip is owed to commenter Henrik on the Rosetta blog, who noticed that the big circular pancake at the bottom of the header photos matched to the depression in the middle of Imhotep. That got the slide matches started for the rest of Imhotep. The post on which he commented is here:
For those readers who are familiar with the missing slabs and are wondering what this crust-sliding means for the missing Imhotep slab, there’s a sub-heading at the bottom that discusses this. 
KEY TO HEADER PHOTOS 
BROWN
The paleo rotation plane (which is also the long axis of the diamond-shaped body). Please see the page in the menu bar regarding a small adjustment in its line. It’s a ~3° adjustment towards the current plane. The current plane runs from the same point on the right to a point on the left where it just clips the end of the mauve area below the name ‘Aten’. So the paleo plane is now more like 10-12° off the current one whereas before it was said to be at least 15° off. The reason there’s no adjustment on the right end is because that is Apis which is at long axis tip and the rotation plane precessed about the long axis- the neatest expected option. Thus, the lines of the two planes cross each other at both of the long axis tips/extremities. The other crossing point is at the top of the Hatmehit cliff, in the middle of the V-shaped Hatmehit slab hinge. The paleo plane isn’t just a wild speculation though it is a hypothesis, based on the ten paleo plane stretch signatures in Part 26 that all line up round the comet (now extended to thirteen in the new page). 
YELLOW
The short axis of the diamond shape, as best it can be discerned given the winter shadowing at the bottom of the frame. It acts as a line of symmetry for the sliding crust, which tore from the line and slid in opposite directions. 
BRIGHT GREEN
The gravitational low of Imhotep as identified in this OSIRIS team paper by A.T. Augur et al. (pay walled):
The paper is discussed in the following Rosetta blog post although the relevant figure with the gravitational low isn’t shown:
Notice how the gravitational low is almost exactly at the intersection of the two axes and therefore at the centre of the body lobe’s diamond-shaped base. It’s also the focus of what appears to have been a very substantial amount of outgassing and slurry ejection. It’s near the centre of a marked depression that exhibits geyser-like circular features and flash-frozen slurry lakes. The depression is dotted light blue in the fourth version of the header photo. 
The circular features and lakes are described in the linked paper and blog post above and referred to there as gas dykes and dust respectively. They don’t mention slurry because liquids are not accepted as being viable in the temperature/pressure environments of current comet models. 
We’ll come to see in the next few posts that all the sliding crust pieces were centred on the depression and slid away from it. If you reversed the slide, they would all kiss inside or along the edge of the depression and do so with a remarkable puzzle-fit affinity.
RED
This is the line of one of the two main rifts across Imhotep. It involved the lower of the two ‘onion layers’ of strata and it tore from along a line that is almost contiguous with the yellow short axis line. The right hand red line is the tear line and the left hand one is where that torn edge slid to. That’s why they run parallel with similar bumps and kinks. This lower layer slid away at 90° to the left of the short axis, hence its final position running parallel to the short axis as well as its tear line. 
The red slide is around 800-900 metres, consistent with the crust slide distances elsewhere on the comet. 
The upper of the two layers slid predominantly at 90° to the lower layer i.e. parallel to the short axis (see the blue lines in the photo and described below in the key). The upper layer slid up to the top and down to the bottom. So when you couple this with the red slide, it’s the reason why the flat Imhotep plain has a long, rectangular shape that is parallel to the diamond’s short axis and exactly straddles the long axis. 
ORANGE
This is the notional mirror image to the red tear and slide. It also involves the lower onion layer. It’s not the same shape as the red rectangle and it involved more obvious radial sliding than the red slide on the other side of the yellow short axis. That’s why it’s said to be a notional mirror image: topologically speaking, it’s executing the same sliding behaviour in the opposite direction, with the yellow line acting as the line of symmetry. It looks a lot messier than the red side but when the radial nature of the slide is borne in mind, it too will be seen to be tearing from along the short axis albeit a little displaced to the right of it. As with the red slide, the orange slide involves the lower of the two crust layers but it’s sliding to the right of the yellow line. And separately, the top layer slid both up to the top and down to the bottom (as stated above, the top layer is the blue slide- see blue key further down).
There are three orange lines. The one at the left, towards the yellow axis symmetry line is the tear line. It’s entirely within the depression. The two detached, right hand and upper-right orange lines match to the tear line. They are much longer than the tear line. This is because when reversing the slide, the slid matches nest over each other in order to fit to the tear line. That’s another way of saying they slid radially: if they slide back in reverse they’re constrained to stack over each other. This isn’t a general assumption, the individual sections will be matched to their stacked seating points in an upcoming post. 
The red slide to the left of the yellow line doesn’t exhibit the same radial stacking behaviour as the orange slide when looked at in isolation- it’s a simple shunt of a notionally straight section of lower layer across the Imhotep plain. However, that changes when you add in the top layer. The current rectangle is deceptive because rectangles don’t usually chime with radial processes. However, the fact that the lower layer slid one way to the left and the upper layer slid at 90°, up and down, is the beginnings of radial behaviour. And yes, they have to nest back over each other in the reverse slide in order to become two layers, one on top of the other. If you add in the green delaminations (see below) the red/green slide on the left is essentially a radial sliding process, the same as on the right. That’s despite leaving such a neat rectangle. The orange slide also has up/down, top layer blue slides nesting over it if you reverse the slide. So both sides of the yellow symmetry line exhibited radial sliding, the only difference being that on the orange side, the radial behaviour occurred within that lower layer as well as in its interaction with the top layer.  
BLUE
The blue slides are the up/down slides of predominantly top layer crust. They slid over the layer below and at 90° to it.
The blue circle with a red slide arrow in the middle is the circular pancake that Henrik suggested was formerly sitting in the depression. The small green dot corresponds to the green ‘low point’ dot in the depression and would have been sitting directly over it. It’s difficult to draw a line it slid from because a) it’s a notional circle, not a line- its seating circle is the depression itself and b) the depression is already cluttered with dots. So this smaller green dot substitutes as a fiduciary point linking to the larger green dot from which the pancake slid. There was almost no rotation so a single dot suffices. We’ll see in an upcoming part that neither the pancake nor the depression is really a circle but they are the same shape and size. 
Just to avert any confusion if you read Henrik’s comment, linked above: he thought the pancake had rotated 180°. Mini matches will show that it didn’t and that it was an almost straight translational slide with a maximum 3-5° rotation. However, this doesn’t detract from the initial observation that there was possibly some sort of match. Sometimes it’s other characteristics you are seeing but can’t quite quantify that are directing you towards further investigation. That investigation, via mini matches, is required to validate or discard the match. This firms everything up but often delivers a few adjustments or surprises in the process. In this case, it showed that there was almost no rotation. 
On further study of the matches as a result of Henrik’s suggestion it became apparent that another, lower layer had slid out of the depression i.e. from underneath the pancake. Those are the red and orange slides described above and they presumably departed after the pancake slid downwards. The pancake is therefore part of the upper layer of crust on the right hand side of the yellow, short axis symmetry line and it used to sit on top of the lower sections that nested together in the depression. It’s the lid of the depression, if you like, and for that reason, it’s the same shape and size as the depression. As such, it chimes with the lid described in the ideal stretch and slide scenario at the top of this post. 
The blue line that’s seemingly attached to the pancake is a presumed section of sliding crust but it has no match and almost certainly isn’t attached to the pancake in any substantive way. Close ups show the join apparently draped with dust or, as this blog would say, ‘welded’ with frozen slurry because the pancake is already half-covered in slurry. But that doesn’t mean they’re structurally linked at all and the strength of the weld would be virtually non-existent. The reason this small, straight section is thought to be a slide towards the bottom, along with the pancake, is that larger, parallel sections of crust are to be found lower down in what is shadow in the header photos. They will emerge from the shadows when the detailed matching is being done in later parts. This short blue line bounds the bottom edge of the rectangle and appears to be a lower section of crust. That’s in contrast to the large section of top crust about to be described, that slid upwards. This means the up and down slides don’t actually involve top layer crust all the way along their perimeters. This small section seems to buck the trend while the pancake to its right is a top layer of crust along with the whole section marked blue along the top of the frame. So three-quarters of the up and down slides are top crust and one quarter is possibly or probably second layer. 
The uppermost blue line is the border of a large section of top crust that includes the large circle traversed by the yellow line and it extends all the way across to the ‘Ash’ name. It slid upwards from the blue line below it. That lower line runs along the edge of the depression and then curves round to run upwards, almost contiguously with the red line.  
GREEN
The green-dotted lines are sections of delaminated crust that slid further on from the classic red slide and orange slide boundaries. They Have green slide arrows too, showing their direction of slide, but the slide vector is in relation to the layer they have delaminated from.  
The left hand and upper-right green lines delaminated in the same direction as the layer they delaminated from. Their arrows therefore follow the same direction as the main slide and look intuitively correct. 
The top-left green line, or rather, green area delaminated at 90° to the layer below it, rather like the upper layer that slid towards the top of the frame. The circle within the green area slid from the notionally circular area where its green slide arrow is placed. And the rest of the green area slid with the circle within the green area. However, if you add the green arrow (90°) slide vector to the classic leftward slide vector of the layer below (red slide; red arrow) you can see that as the main slide was moving left across Imhotep, the green area was moving both leftwards and up. In other words, when the two slide vectors are added, the green area slid at a 45° angle from the big bright green dot in the depression. To be precise, the bottom-right green dot of the green area used to kiss the slightly brighter small patch to the above-left of the big green dot in the depression. That’s the patch that touches a red dot. 
Despite sliding up at 90° like the top layer, the green area slide is part of the lower layer. It originally sat under the blue slide chunk of top layer that’s now situated to its right. There’s a little more to the green area delaminations and slide vectors which will be presented in greater detail in due course. But in brief, appears the green area was originally attached to the left hand green slide (see below) which means its 90° slide was even longer and involved an extra mini-delamination. The evidence for all this movement will be in the form of highly refined mini matches and signatures all along the slide itself. Ice signatures will also be seen to match. 
The left hand green slide is also an extra slide beyond where the red slide stopped. The tip of the finger-like protrusion nests to the brown dot that’s to the right of the big green dot in the depression. It looks as though the green line of this slide should continue curving round beyond the topmost green dot and touch the left hand red line to make a neat mirror image of the two horseshoe shapes. However, it appears that the topmost green dot slid from the red line, specifically, the top of the red line’s kink above the ‘m’ of Imhotep. If you reverse the green slide, it means the finger is shoved a long way to the right of the red line as is the bottom section or horseshoe. That allows the finger to kiss its brown dot in the depression if we slide the two nested layers, red and green, back in unison across the flat plain. It also allows the bottom half of the bottom horseshoe to be far to the right past the red slide line as well. This places it far enough to the right to be just beyond the tip of the finger. That’s far enough for it to wrap round the bottom perimeter of the pancake (when the pancake was in the depression). This bottom half of horseshoe is the same shape and size as the bottom perimeter of the pancake, although it doesn’t look to be in this grainy overview. 
Most of this left hand green slide appears to be top crust except for the majority of the finger which looks scalped. That’s to be expected because of course the finger sat in the depression under the pancake. The the finger betrays an ice signature along its upper edge as does a small lump in the depression along that upper edge of the finger’s seating line (it’s either the brighter patch mentioned above or under the red dot next to it). You may recall that the bright patch in the depression is where the upper left, green area kissed. This means both green slides kissed each other in the depression. They will be shown to kiss via the matches anyway but they also match on their ice signatures. That corner of the green area that kissed the bright patch has its own very strong ice signature too. And it is only that corner that is matched to the depression. The rest sat outside, along the depression’s edge. So the only two parts of the green slides that sat in the depression have ice signatures and the place where they sat in the depression also has an ice signature. Moreover, apart from strewn boulders with faint signatures, these are three of the four main ice signatures to be found anywhere on Imhotep. Seeing as the green slides are already matched to the depression via mini matches, the accompanying ice signature match would be an amazing coincidence if it had happened by pure chance. 
The majority of the strewn boulders with faint ice signatures actually trace the line of the top-left green slide. They form two lines across the flat plane at the aforementioned 45° slide vector. The two lines start at either end of the seating match already made alongside the depression. They continue uninterrupted until they reach either end of that uncanny-looking rectangle within the top-left green area, the one that looks like a wide ski ramp. It was this rectangle, overhanging the red slide it was piggybacking on, that distributed the icy boulders from both its ends. Because it was moving across the plain at 45°, it distributed the two signature lines at 45°.
The ice signatures will be explained in more detail with a linked OSIRIS scientific paper.
The top-right green slide appears to be the top crust layer that slid on past the classic, orange bottom layer. It slid in the characteristic radial orange slide manner.  
FUCHSIA
The four fuchsia dots at top left are the four slid cuboids from Part 40. We are looking up at their undersides because we’re looking at the base of the comet. They are simply shown here for context and are irrelevant to the Imhotep crust slides.  
SLATE BLUE
This is the left hand tip of the body lobe diamond shape. It denotes the true flattened diamond tip. It’s the very defined rim in Khepry where it turns sharply to become the base. It runs along a sharp ridge which is the width of Khepry. At first glance, it looks as if the flattened tip should be wider but the section at the top (not dotted slate blue) is one of the Babi cuboids that’s set back somewhat. The true, slate blue line makes this flattened tip satisfyingly similar in length to the opposite flattened tip at Apis. Both are equal length sections of residual crust that appear to have modified the stretching tip in an identical manner at both ends. The only difference is that Khepry extends upwards to join Aker and together they form a noticeable bow to the body diamond that is the width of the flattened tip all the way up. At the Apis end the width of the flattened tip is the length of the small lozenge that is Apis.
The two tips are the least disturbed parts of crust on the comet. Every other region has suffered upheaval of one sort or another. Whilst Khepry may be scalped slightly, I suspect that Apis is pristine crust or at least pre-stretch crust insofar as stretch theory explains its morphology. For that reason, the Rosetta team could do no worse than to study Apis more intently than the rest of the comet. Since Rosetta went there to decipher the secrets of its formation, this tiny area may give up those secrets as it is probably the oldest feature on the comet. 
CONCLUSION
The Imhotep slide matches will take a few posts. There are still a number of posts to come regarding the crust slide on the head lobe at Ma’at (the section of Ma’at that’s to the right of the cove) and delaminations along the shear line at Hapi below it. However, Parts 31-41 explain these same mechanisms for the adjacent section of Ma’at (to the left of the cove) and shear line below that section at Babi. The sewing up of the right hand area with five or six more posts, whilst very interesting, is more of a formality. Imhotep seems more important for the time being. 
MARCO PARIGI’S BLOG
Marco Parigi has a stretch theory blog as well. It describes many of the aspects of stretch in more concise terms than here and with annotated photos. It then links to the relevant posts in this blog for those readers who want the full, in-depth analysis:
Marco thought of stretch theory, as it would be applied to comets in general, and did so long before Rosetta arrived at 67P-CG. My first realisation regarding the possibility of stretch was on seeing the first published close-up of 67P on August 6th 2014. 
A NOTE ON THE IMHOTEP ‘MISSING’ SLAB
The crust-sliding across Imhotep is so extensive that it calls into question the existence of the Imhotep missing slab that was described in Part 13. There is clearly a large area that appears to have gone missing, what the OSIRIS team morphology papers refer to as mass-wasting. Even the Rosetta and OSIRIS teams believe it has eroded away via sublimation erosion. 
The sliding crust pieces described in this overview appear to zip back up quite nicely, and possibly negate the need to invoke a missing slab. There doesn’t seem to be a vast chunk that’s still missing but that doesn’t preclude smaller pieces flying off. 
The Imhotep slab was said to have been lost through going into negative g via spin-up and been released when its tangential velocity was above 0.8 metres per second. That would be the comet’s escape velocity and would be achieved at a 2.5- to 3-hour rotation period. If the slab didn’t need to escape but is in fact the crust that slid back on Imhotep then it’s likely that the rotation period was somewhat under this value, leaving the crust weightless and able to slide around while it was weightless. The weightless rotation period would be root 2 times the escape velocity rotation. That’s 1.41 x 2.5 hours or 1.41 x 3 hrs. So say 4.2 hours.
However, it still appears that a slab is missing from Hatmehit and there appears to be missing (not slid) material at Anubis and the south pole. The only way for that material to be missing is for it to have departed the comet at above 0.8 m/sec. So we’re back to the faster spin-up again but with Imhotep not losing a slab. Like the slab A extension (Part 23) and the three sink holes (part 32) this paradox will probably get resolved in due course. 
PHOTO CREDITS:
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
All dotted annotations by Scute1133.

Saturday, February 20, 2016

Philae found by Rosetta's narrow angle camera on Abydos, 67P

In this new post, Philae found, a very comprehensive argument is made for the discovery of Philae's glint in a recently released OSIRIS image.

The precise location of Philae in Abydos, has been of intense interest to the entire Rosetta mission's team, for both scientific reasons, and sentimental ones as well for all interested watchers. Using mainly photogrammetric techniques, mere pixels from the most highly detailed images now available, can indicate the spot. Other explanations for the pixels to be visible there have become more and more unlikely, enough to be ruled out now, given many images of the same location.

Wednesday, December 23, 2015

Scute reblog 67P comet sinkhole delamination part 32

67P/Churyumov-Gerasimenko. A Single Body That’s Been Stretched- Part 32

THE LARGE SINK HOLE DELAMINATED INTO THE THREE SINK HOLES WE SEE TODAY.  
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/SGS/PSA&ESDC/Scute1133
Photo 2- the ESA comet regions map to help with locating the regions referred to below. 

BACKGROUND
Part 31 presented the lattice of stretch vectors in the so-called slab A extension and the red triangle. The stretching of 67P was due to the ‘centrifugal’ force brought about by the comet spinning up to somewhere around a two- to 3-hour rotation period. The spin-up would have occurred via asymmetrical outgassing. Alternatively a close pass at Jupiter some way under the 220,000 km Roche limit would supply the stretching force via differential g accelerations instead of spin-up. 
Part 31 stated, “there are other areas nearby that show similar stretch vector signatures that are orientated at a slightly different angle from this lattice.”
If we trek across Ash from the red triangle and round the perimeter of the slab A extension, we cross through the lattice and end up in an area behind the three sink holes. Here, we find an area with lines that resemble the lattice but they are fainter, broken and further apart. Also, their aggregate direction seems to be at a slightly different angle from the lattice orientation around the red triangle. It all looks a bit woolly. 
Photo 3- the smudged lattice lines in Ash (larger dots). 

But let’s look at those lines in detail.
Photo 4 – the Ash matches behind the three sink holes. Includes unannotated version.
   
Photos 4 and 6 have narrative keys so the end of the key is denoted by the symbol ‘/////’. 
Fuchsia- the fuchsia circle is the large sink hole at one end of the flat area of Site A. The two horseshoe arcs below it depict the other two sink holes set in line behind it and towards the back of Site A. They are smaller, shallower and joined to the main one. The three together form a trench with bulbous sides. 
Long terracotta line- the shear line for orientation purposes. The terracotta L-shapes in Ash are stretch matches (see below). 
Yellow next to shear line- the beginning of the Site A ‘crater’ perimeter. The rest is left out so as not to clutter the photo. 
Orange- missing slab B (Babi-Part 9).
Bright green- on the right running away from the shear line- this is the right hand perimeter of the slab A extension. It’s contiguous with one long side of the red triangle. Bright green is also used for the triad of matching bright green dots (see below) because when nested they sit almost at the opposite end of the slab A extension.
All other coloured dots, which are all below Site A and sitting in the Ash region, depict specific features that are repeated on the three recoiled layers. 
Red arrows- these depict the directions in which the matches flare out across Ash and therefore betray the the direction of the stretching forces acting on them. 
/////
We can see the matches flaring out wider as they extend down Ash, away from the Site A crater rim and sink holes. If we replay the stretch movie backwards, the bottom layer of matches moves up Ash, contracting slightly along its length (horizontally in this view) as it does so. It scoops up the second line as it passes it and then the two nested lines move further up Ash. Again, they contract across their length as they approach the third line of matches and nest with them. This time, the horizontal contraction is more marked and means that the red, blue and dark green matches get lost in the squeeze, leaving just the outside two to join together: the terracotta L-shape and the bright green triad. The focus of the contraction is the third sink hole which is the second one from the main, large sink hole. This means that:
1) The stretch vector lattice does extend further across Ash and all the way to site A. 
2) The whole of Ash is one giant recoil area. That at last explains why the back rim of Site A continues on in a perfect arc along the back rim of the slab A extension- all the way to the red triangle (see photo 5, below). Both areas were subjected to the same stretching and recoil event. Ash is simply an onion layer that slid back under the influence of the stretch vector after decoupling from its counterpart a long way further up the body and somewhere on site A (and the slab A extension). That beautifully smooth arc betrays the subtly changing orientation of the stretch vectors across Site A, the slab A extension and Ash. This may be the reason that Ash looks a bit like a crumpled blanket. It didn’t lose material and in fact consists of excess, flaccid folds as a result of material that slid back. For regular readers who can stitch together all the references to the Slab A extension morphology since Part 22, this has now almost fully explained its morphology: the scalped skin split in two. Half is plastered against Anuket and the other half recoiled back to this curved line and is now part of Ash. The tear was about midway across. It was acknowledged as not being fully understood back in Part 22 and said to be a work in progress. It was stated that it must have been subjected to the same process as site A but what that process was remained a mystery. The answer is recoil and in retrospect, it looks rather obvious. All those references regarding the demise of the slab A extension will be collated into one post fairly soon, along with some extra evidence.
3) The three sink holes are orientated in line with the average direction of these newly discovered stretch vectors that flare out down Ash. Since all the matches converge on the third sink hole, it means that this sink hole and the second one behind it had to have at least been under tension along this vector. Since the vector is in line with the alignment of the holes, it’s reasonable to suggest that the holes delaminated along that line, from one big hole into three holes. Indeed, all delaminated strata either side of the sink holes is delaminated in this same stretch direction (see photo 6, lower down).
4) The stretch vector change betrayed by the Ash recoil curve is radial, meaning the vectors are focussed (nearly) on one point, right next to the north pole. That’s a huge clue for stretching via the centrifugal force of spin-up.
Photo 5- the Ash recoil showing the neat curve where the Ash onion layer recoiled to. 
   
Yellow- portion of Site A (the missing slab A crater) up to where its back rim merges with the slab A extension back rim. 
Bright green- the slab A extension back rim that continues on from where it merges with the Site A back rim. 
Photo 6- the delaminated layers next to the three sink holes. 
   
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/SGS/PSA&ESDC/Scute1133
Fuchsia- the three sink holes. The main one is nearest to us and the delaminated ones are shown as horseshoe arcs beyond it. Looking at the floor level of the second hole, it’s on the same level as the large, flat expanse of Site A to the right as well as the smaller expanse to the left (at the bottom of the dotted terraces). This is a strong clue that the side walls of the main sink hole slid back along this fracture plane thus revealing the floor of the second sink hole which was previously sitting under the slid-back strata. It is therefore not a sink hole at all but the sliced top of the main sink hole, sitting on a newly exposed flat expanse. The same process would apply to the third sink hole, the only difference being that the revealed floor of that hole was another stratum or sub stratum further up from the second hole. Despite not being sink holes, after all, we’ll continue to call all three “sink holes” for the time being because they are called that by everyone who is interested in 67P. Even the main hole will eventually be shown not to be a sink hole- at least not in any conventional definition of the term whereby a cavity slowly forms and the roof collapses. 
Red arrows- the upper pair show the direction of travel of the fanning-out matches, thus betraying the stretch vector that pulled them along those two  paths. They point upwards because we’re looking from the opposite direction to photo 4 where they were pointing downwards. The single, lower arrow is pointing at the large sink hole. More importantly, it’s pointing in the direction along which the line of three sink holes is arranged. And this direction is in the average direction of the other two arrows. Hence the three sink holes were under a tensile stress force in this direction while everything around them was actually moving back down the comet under that same tensile force (proven by the matches). It’s therefore reasonable to suggest that the holes were also delaminating in that direction. 
Bright green, blue, dark green and terracotta- these are the same features as in photo 4 but viewed from the exact opposite direction and from lower down. So they are converging towards us in a foreshortened perspective. The yellow and red dots are left out because they’re whited out here. Also the ‘lower’ dark green dip in the other photo is invisible here. The ‘lowest’ terracotta feature (highest here) is almost unrecognisable due to foreshortening so it’s left unannotated for fear of obliterating it. It continues beyond the second terracotta match in a zig zag. 
Light orange- this and the first terracotta L-shape match that touches it were depicted as one terracotta L-shape in photo 4. That’s because it was fuzzier and in shadow in that photo. Here, it’s divided into the initial seating area, which is the pale orange dots, and the first terracotta match that slid back from it. You can see that the first terracotta match is a right angle with a thick finger of material. If you reverse the stretch movie, the finger slides towards us and clicks into place over the finger depicted by the pale orange dots. Its right angled part then clicks into place by curving round the back of the third hole but it may have just gone straight across the back of the bright green dots. 
Pale green- strata that delaminated in the same direction as the average tensile force (stretch) vector. That would be the same direction as the delaminating holes. There are terraces of multiple matches fanning out on either side of the holes. 
/////
Photo 6 basically shows everything in the vicinity of the sink holes getting yanked back, away from our viewpoint towards and across Ash. All this material would have originally been nested together with the three holes themselves also nested together. 
THE LARGE, ISOLATED CRATER IN ASH MAY BE RELATED TO THE SINK HOLE  

Photo 7- the crater in Ash. It has a light blue dot in its centre. Its twin in the ‘flared matches’ second tier is beyond it, also dotted light blue. Photo 4 also gives a good view of it. In that photo it’s got the dark blue matches either side.
There’s a match in photo 4 that wasn’t annotated. It would have cluttered up the image too much. That strangely isolated crater in the middle of Ash is sitting right in the middle of the matches. It’s the only large, circular crater on the comet with a completely intact rim. It’s also absolutely constrained to rise up Ash with the matches around it. And when we look at photo 4 again we can see that there’s a big circle right above it, in the correct direction of movement. It’s not just sited anywhere further up and in the right direction but it’s shadowing its L-shaped terracotta match on the other side of the flared set. In other words, the layer it delaminated from is the same as the the one from which its partner L-shape delaminated from before they both slid and flared another level down. The same principle should work with the next layer up. The L-shape has already been matched to the side of the third sink hole. If the crater behaved as it seems it did, sliding with the L-shape from the second to the third level, then it must surely have slid with the L-shape from the first to the second level. That means it was crammed right against the L-shape at ‘level 1’ and that in turn suggests it was sitting right on top of the third sink hole (presumably when it was an incipient sink hole). It would seem remarkable for a crater to move that far and stay intact. But the matches already constrain it to move from its circular, level 2 twin to its current position so if it had to move from there it’s not so implausible for it to have moved the whole way. And since we are saying that the three sink holes delaminated and that crater in Ash has now been traced to the third hole, it’s just as conceivable that it originally sat over the main sink hole before it delaminated into three. 
As a check, one can look at the unannotated version of photo 5. If you concentrate on that smooth curve forming the back rim of the slab A extension, that betrays the stretch vector or tensile force vector because that’s the curve along which it found its equilibrium after springing back. The tensile stretch force would be at 90° to the curve. If you draw a line between the crater and the main sink hole, whether it’s straight or via its slightly kinked matched path, it crosses the curve at 90°. If you replayed the stretch movie in reverse, the crater would always be headed for the large sink hole.
PHOTO CREDITS FOR NAVCAM PHOTOS:
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All dotted annotations by Scute1133.
PHOTO CREDITS FOR OSIRIS PHOTOS:
-Original image provided as .IMG file in the archive delivery from : ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
-Original image processed by ESA/Rosetta/SGS/PSA&ESDC to create image for Archive Image Browser
All dotted annotations by scute1133.

Tuesday, November 17, 2015

Stretch theory Abstract and links

Abstract



 Comets are widely thought to be pristine remnants of the solar system's formation, and thus their study has been historically interpreted in that context. Evidence to date suggests that comets are far from pristine and the surfaces are heavily processed in very recent geological timescales.



 Evidence presented here points to the overall shape of 67P Churyumov Geramisenko also being from a stretch event in very recent geological time scales rather than being from either directly from the surface processing or from its initial accretion from the solar system's formation.

This evidence falls into broad categories of:

 1) Matching large scale mirrored features from head to body around virtually the whole circumference of the nucleus.

 2) Mini matches and 3D matches within high resolution images constrained by the position of the large scale matches.

 3)  Evidence of the removal of slabs due to the forces at play during stretch.

 4) Cracks perpendicular to and crossing the rotation plane.

 5) Monoliths matching their initial seating points.

 6) Evidence of the head lobe stretching before breaking away.

 7) Evidence of Dykes, slurry piles and related outgassing.

 8) Evidence that would falsify Contact Binary and Erosion theories.





 Thus while still being extremely relevant to the understanding the history of the solar system, the extreme recent processing would mask any relevant evidence from the initial formation of the solar system, and asteroids are more likely to hold more clues in that direction, especially with impact crater records to verify age of surface.

Monday, November 02, 2015

The Case for Continuing Stretch of 67P

There are a number of points of evidence on the neck of 67P which is telling us the evolution of the shape of the nucleus, and perhaps of comets in general. The swept back nature of Hapi, along with the roughly circular cross section of the centre of the neck is a pointer that the neck has evolved from stretching. The case is strong that the bilobed shape of 67P is from a stretch event that has kept the evidence from initial fracture in the matching shear lines of the lobes. That enables us as modellers to piece backwards that the original shape was roughly ellipsoid. However, the interpolation of the intermediate neck stage, and the timescale between intermediate stages is not able to be determined based just on the mechanisms hypothesised to be acting on the nucleus.

Next we can look at the formations on the neck and see if they can be connected to ongoing phenomena, which would allow us to extrapolate back a little bit. Cracks are ubiquitous on Anuket. Anuket is otherwise *not* covered in dust or rocks, but has the texture of quick dry cement. A lot of formations perpendicular to the neck give the impression of an evolving process related to the cracks. Cracks are notionally perpendicular to the rotation plane, cross the equator and appear open wider at around the equator. Outbursts are also seen to happen at Anuket which are likely related to the cracks.

A continuing stretch hypothesis is that the cracks open up at Anuket due to the nucleus rocking on the neck due to asymmetrical outgassing torque. The cracks then get filled from below by a slurry, which quickly hardens on exposure to vacuum. As the head rocks back, cracks open up at the neck on Bastet at the opposite side of the equator, which also gets filled in. The cycle has a net effect of lengthening the neck, absorbing the torque (and precession) which would otherwise accelerate the rotation even more, with the conservation of Angular Momentum and increased gravitational potential absorbing the torque energy. Each rotation may have the width of a crack lengthening of the neck, and the resultant neck feature would appear like a ridge or paired ridges either side of the crack, still notionally perpendicular to the neck. That would explain the myriad perpendicular ridges and valleys on Anuket and perhaps Bastet. This would mean that this process would have been happening steadily for quite some time, and that the original stretch event perhaps only travelled half way from an Ellipsoid to the current duck shape, and the rest has been happening over many perihelions since.

Accurate measurement of neck length evolution (or lack of evolution) will illuminate this situation.


Monday, April 06, 2015

The Growth Problem

As far as I can see, the "growth problem" with respect to comets is that without growth, there is no life cycle, and I accept that. That begs the question, however, that if I did not believe comets could grow, I would not believe that there could be a life cycle.

What it comes down to is that comets must have grown, otherwise they wouldn't exist. The scientific consensus is also that their active life is very finite - ie. That within a few million years of having reached the sun's neighbourhood it would either collide with a planet or the sun, or lose all its volatiles, or be ejected. This presumes that the movements, and thus the destiny of individual comets are completely determined by essentially random factors. The trivially nonrandom influences, such as outgassing, spin rate and YORP accelerations can in no way mitigate against this to have comets with features that allow for its continued survival. Essentially it is an "antidarwinist" philosophy. All comets are equally destined to die, regardless of their underlying differences and trivial nonrandomness. 

If we are looking at the comet for a life cycle, we are looking at a tiny slow motion sub segment. If we didn't know what a seed pod for a Brasil nut tree was, it looks lifeless and incapable of growing. Imagine if we could only see different pods at different times after being dropped from a tree, and never be able to see the tree, or even inside the pod. There is hints that the seed pod could break up into smaller seed pods. Clearly seeing where the seed may grow is crucial to working out whether we are looking at a rock, a living thing, a dead part of a living thing, or something which living things could be inside. Failing seeing growth, we could look at the chemistry of its surface, try to see what is inside. However, the two basics of life - reproduction and metabolism are the most crucial. 

Noting that brasil nut seed pods are similar to each other, and different to more obviously lifeless rocks around it is an important technique. Also the porosity of the exterior substance, the evidence that it has a shell and an interior that may have different properties.

This may indicate that if comets are living, it is the internal payload that is the most crucial, and that the only stage that we are seeing is the dissemination of panspermia comet seeds, and that we are seeing it in extreme slow motion. Maybe a molecular cloud passes by every few million years, and the cometary seeds that are lucky enough to find themselves in that cloud get a chance to grow, hence the importance of spreading the comet seeds widely, so that some get a chance to grow to keep the life cycle going.

This is highly speculative, of course, and it has nothing to do with the evidence that can falsify or fit with reproduction and metabolism.

Saturday, March 14, 2015

Letting Go of Abiogenesis

In an earlier post in regards to standard evolutionary synthesis, my point was that simple "natural selection" on "random" mutations fails for the very Darwinian reasons the idea originated from. If it ever was the primary mechanism, it would have died out quite quickly from obviously superior mechanisms (that are, nevertheless adaptive in the same intuitive sense for reproductive success). At least, that is my conclusion and thesis.

Looking at a particular *new* *beneficial* mutation that one time or another has to happen on a path to some species to another more adapted to a particular environment, the probablistic difficulties are similar in scope to what is envisaged in abiogenesis, but of course, having working and sophisticated superior mechanisms already in play is different from something where you really only have the laws of physics, chemistry and probability as envisaged with abiogenesis.

All efforts to demonstrate in principle either backwards from the simplest life we know, or forward from the most complex non-living carbon based systems we can imagine, have come up with a blank. It reminded me of the difficulties and paradoxes with Euclid's fifth Axiom, and also the paradox with measurements of the speed of light being constant at different relative speeds. Most who research abiogenesis in some way or another don't perceive the paradox so much as it being difficult to conceive and not having evidence to lead you in any way or another to point in the right direction.

My idea was to, like mathematicians in their time, presuming Euclids fifth axiom false, or Einstein in his time, presuming the speed of light to be constant at all relative velocities. If one presumes abiogenesis as currently framed to be not just difficult, but actually impossible, where does that leave us with naturalistic possibilities with the origin of life?

My idea was to make this a bold falsifiable theory, and hope that some evidence would actually bear on it to rule it out or not. Certainly it makes perfect sense to me, but I want to give all support and aid anyone who thinks it can be proven wrong by some experiment or new observation.

My alternative to a process of abiogenesis to go from no life to chemical life, is instead that chemical life is designed (in an evolutionary process of design) by a life form which is not directly chemical based. I was thinking along the lines of Hoyle's dust cloud life as something at a similar place in idea space. My other thought was that the proximal antecedent to chemical life would use its own life cycle as a kind of template for the first independent living cell, which would have to be something like an amoeba.

When I first saw the image of Hartley 103P with these abiogenesis ideas in my head, I felt that comets were the only real candidate for life's proximal antecedent. Over spans of thousands to millions of years, they use the interplanetary superhighway to move from orbit to orbit expending very little relative fuel. To reproduce, they expend a great deal of energy speeding up their spin in a controlled way, stretching into a bilobed shape then continuing the spin up and stretch until it is two almost independent bodies tethered by a long skinny neck, which tidal alignment would easily sever "the umbilical cord" and the two separate comets would go their separate ways.

In light of this, for most of their lifespan, comets would be completely "dormant" and essentially invisible. Thus dark "asteroids" like Bennu, which is likely to be visited soon enough should have almost all the same features as comets, bar the outgassing. The distinction between live/dormant comets and 
dead asteroids would come down to colour - the lighter they are, the less likely they are to be just dormant, and features dominated by impacts rather than cometary flaking/stretching/outgassing would be a "dead" giveaway.

Anything opposite to this, I would feel would easily falsify my hypothesis. It being based on assuming abiogenesis as currently framed impossible, and comets being the proximal biological precedent. The former being broadly "M life theory" and the latter "living comet theory"

Quite frankly, I'd be very satisfied if they were falsified - my investment in the theories is based on an unshakeable hunch that they are right. I want to find evidence that they are wrong - please help me.

Sunday, March 08, 2015

The collisional Problem (reblogged from Scute1133)

original post

CAN CONTACT BINARY THEORY EXPLAIN THE HEAD-TIP AND FRACTURES ON THE ROTATION PLANE? (To be read in conjunction with Part 10). 

2015/01/img_2266.jpg
“The Collisional Problem”. I might have dreamt that up as an apt subtitle for this post because by the time we’re done it will surely be merited but, too bad, I was beaten to it. Those words were already taken as the subtitle for a poster accompanying a talk on 67P’s status as a contact binary. The venue was the American Geophysical Union (AGU) Fall Meeting in December 2014 and the verdict on that binary status remains equivocal.

The abstract for the presentation was entitled,”The Nucleus of Comet 67P/Churyumov-Gerasimenko : a New Case of Contact Binary?” 

https://agu.confex.com/agu/fm14/webprogrampreliminary/Paper13889.html

It acknowledged that:

“A contact-binary among the Jupiter family comets (JFC) such as 67P would have profound implications since it must be primordial and the comet must have survived a possible history of collisions in the Kuiper belt. The present cumulative distribution function of size of nuclei of JFC comets indeed suggests a collisionally-relaxed population.”

In other words, there is countervailing evidence that militates against the existence of contact binaries in such a “collisionaly relaxed” population.

The collisional problem is, however, just the first of many for the CB theorists. They might be able to attempt an explanation of the rotation plane head-tip and fractures but not without jumping through flaming hoops in the process. They seem up to the task though. The AGU abstract considered the “unlikely…scenario of a re-accumulated body following a catastrophic collision” (because it really ought to have been blown to smithereens by now), as if it was a last resort to explain the two-lobed shape as a contact binary.

True to say, everything should be considered. Asymmetrical erosion (carving out the lobes via lopsided outgassing) was given a fair hearing too. But it seems the notion of ditching both theories altogether and contemplating stretch theory was just one step too far. 

At least one of those authors presented again two weeks later, at the American Astronomical Society’s 225th meeting (AAS 225, 4th to 8th January 2015), still referring to 67P as a contact binary or possibly a single, eroded body. Again, the phrase “a new case of contact binary?” was used, along with the poster, still reminding us of the collisional problem.

But the answer to the collisional problem was on the poster itself! It had a picture of the comet, looking straight down the z axis of rotation. The visible perimeter, the horizon, was therefore the xy rotation plane and the lower-right horizon was where the fractures happen to straddle the neck at 90 degrees. Furthermore, the uppermost tipping of the head kisses that horizon line too, right above the fractures.

That poster was what made me twig the relationship between rotation plane, spin-up, head tip and fractures that lead to this twinned pair of posts. So the answer to the collisional problem is what it was telling us all along- that 67P can’t be a contact binary. But you had to let go of CB theory fully, if only momentarily so, in order to see the hallmarks of stretch theory depicted on that poster. They are crying out at us: rotation plane, head-tip, fractures.

Here’s a tweet of “the collisional problem” poster:

https://mobile.twitter.com/allplanets/status/545637097797730304

Not much AAS 225 or AGU 14 material is available so we had to rely on tweets. I believe that at least two tweeters quoted here were present at the talks and the third, possibly so, or an astronomer with a live feed of some sort. I can’t be certain of this but they all seemed informed and genuine. 

Respondents to the above tweet and elsewhere on the #AGU14 hashtag, some from respected institutions, were happy to support CB theory. One suggested tidal friction leading to tidal locking (of head and body) and then settling against each other. Another supported the asymmetrical erosion tack but no one considered stretching. 

Incidentally, I can’t imagine a secondary with one side as flat as that shown in the photo below, offering that side up to the primary in an attempt to lock tidally. It would be inherently unstable. If it ever locked at all it would only be stable if it was the other way round with the topmost ‘crater’ facing into the neck. The reason it’s stable in stretch theory is because it always had a supporting neck to attenuate excessive tipping via compressive resistance to any downward vector on any side. This would even have been the case when it was ‘weightless’ during the stretch because the ‘locking’ referred to above is in two of the three rotational axes of the head, not its translational stretch. There are signs this compressive resistance did indeed happen because the head tip only went so far. Here’s the photo:

2015/01/img_22231.jpgPhoto from Part 10. Blue dots: xy rotation plane; yellow dots: ends of one fracture among several. 

Of course, this remarkably flat underside of the head can now be seen for what it is. It’s simply the extension of the now well-documented cliff, reemerging on the other side of the neck. This was the first photo to come out that showed it, proving the head lobe has a flat underside all the way across and overhangs the neck evenly on both sides. The entire plane seats itself back down neatly all round the currently visible portion of the comet body and will doubtless prove to do so on the dark side when it comes into view.

At another AAS 225 presentation, 67P was presented as a contact binary, plain and simple. The presenter pointed out that while several other comets had rocks joined end-to-end, this one had one on top of the other so it looked like a sphinx. That’s actually a far from fatuous distinction, though I’m not so sure anyone was aware of the fact. It should immediately point to the reason the head is tipped up at the back and lead on to the underlying mechanism at play: spin-up, leading to head-tip, stretch and transverse fractures. The head was thrown forward during spin-up due to the very fact that it’s “on top” and not at the axis extremity. But this fact becomes clear only if the rotation plane is considered. 

So, yes it does look like a sphinx but the contact binary assumption made on the way to that conclusion is troubling. The “on top” reference was unwittingly portentous but it became just an interesting observation in the absence of any willingness to loosen the grip on CB theory. Here are the relevant tweets:

https://mobile.twitter.com/girlandkat/status/552252787837648896

The presenter went on to say that the fractures in the neck were due to the head rocking against the neck. That’s true up to a point. It’s due to the head tipping forward during the stretch, among other things, but “rocking against” (the tweeter’s words) suggests random movement with no known cause. Here’s the tweet:

https://mobile.twitter.com/lauravican/status/552253732109307906

As if this succession of respected presentations wasn’t enough to leave stretch theory buried for good another American Geophysical Union presentation, on December 18th 2015, managed to take all the evidence as presented in Part 10, which proves the comet stretched and use it, in error, to prove the exact opposite: that 67P’s shape resulted from the head lobe crashing in from the opposite direction. A sure case of a contact binary. Here’s an article from Wired magazine that reported on that presentation:

http://www.wired.com/2014/12/rosettas-comet-shaped-like-duck/

The reasoning went that, seeing as the strata in the head lobe and the body lobe don’t align, they can’t be related and so they must be two different bodies that drifted together. But the only reason they don’t align is the simple fact that the head has tipped up, taking them out of alignment. The Wired article explained that using new images taken with Rosetta’s OSIRIS camera, the presenter and his colleagues found “terrace-like layers” on the comet’s body and that:

“The layering aligns perfectly with parallel lines seen on the opposite side of the body, suggesting that these layers extend through the body as part of its internal structure. Although the head also has layers, they don’t align with those in the body, which implies that the two lobes were once two separate pieces. If the head and body were made from one piece, the layers should extend through both lobes in the same direction.”

This line of thinking presupposes that the only alternative to contact binary theory is asymmetrical erosion gouging a scoop out of a single rock. The only way the presenter could envisage the strata lining up through both lobes was in the scenario where a single body started out with its strata intact all the way across and then this scoop was removed, leaving the two separate lobes but with their strata still in alignment. 

That assumption is what steered the presenter away from the most obvious solution- that the head had tipped up, taking the strata out of alignment. If it was tipped back down by 30-40 degrees and seated onto the body, the strata lines would align perfectly, as demonstrated in part 6 of this series.

But it was the head-tip itself that led him to believe that that strata had always been out of alignment so this crucial piece of evidence that so strongly points to stretch theory was used unwittingly and in error to ‘prove’ instead that contact binary theory is correct.

That is a perfect example of the adherence to a cherished theory blocking out even the very thought processes that might lead to the correct theory- a case of fitting new data to an old way of thinking, rather than letting new information speak for itself.

It is also of note that this hypothesing around the finer points of CB theory is based on the highest resolution photos from the OSIRIS camera on the Rosetta orbiter. Just a few scientists are privy to this data at the time of writing (including those with the collisional problem) and it was my honest opinion that they could not help but alight on stretch theory with the abundance of evidence before them, much of it still to come in the next few parts of this series. 

However, the Wired article went still further:

“The neck of the comet also shows signs of a collision between the head and the body. The region is covered in big fractures, [the ones straddling the xy rotation plane in the photo above] which would have been created by shockwaves that blasted through the comet during a crash. Some of the fractures are also misaligned, suggesting that they belonged to what were separate, smaller chunks that were floating around when the head merged with the body.”

I have never seen a compressive force cause fractures in a concave surface without it resulting in an explosive shearing event. There’s simply nowhere else for the material to go. Witness compression-testing of concrete pillars that aren’t even concave. They explode dramatically. If further compression of the comet’s neck material is invoked to counter that claim, it is self-contradictory because if it can compress still further it won’t fracture. Indeed, with a porosity of 74%, the neck would have plenty of give in compression and at most it would simply bulge out in folds. But it would not fracture under compression unless it sheared violently as well. 

The fractures have clearly resulted from tensile, flexion and torsional forces none of which are compressive (except where flexion compresses the opposite side of the neck). 

Incidentally, the mention that the fractures are ‘misaligned’ is interesting. Their average direction is distinctly at right angles to the rotation plane and in successive parallel lines. Yes, they do make noticeable excursions from that simple large-scale picture, presumably due to structural anomalies, but the overall impression is as presented in the photo above and the others in Part 10 (reproduced below). 

So, according to this second AGU presentation, as well as the head rocking against the neck (on the sphinx), it had first of all collided with the neck, which was apparently ready-formed, protruding into empty space and pointing in exactly the right direction to make the catch. Once captured, the head ended up perfectly centred with its flat plane conveniently facing downwards, allowing it to overhanging evenly all the way round the neck. That’s quite an impressive claim, provoking at least four tough questions.

Moreover, even if the idea of the colliding head causing the fractures appeared to have some merit at first glance, it wouldn’t explain why those fractures are clustered in parallel lines, at one end of the comet, exactly straddling the rotation plane, at 90 degrees to it, sitting right under the most tipped-up part of the head, and found nowhere else on the neck.

That’s six more really tough questions, ten in total, for the CB adherents to answer regarding the collision of head and body- and that’s the real collisonal problem here, the one that truly merits the subtitle.

The simple answer is that this is where the neck stretched the most and the head tipped forward. Stretch theory would not only answer those 10 questions with ease, it would also predict all ten outcomes as being highly likely.

If they did somehow manage to jump through all ten hoops, the CB theorists would then have to go on to explain why the plan-view matches between head and body were irrelevant- along with their corroborating 3D matches (Parts 1-5). Then explain away the ridges that straddle head and body, followed by the matching strata layers (Part 6). After that, the 30-metre uplifted ‘gull wings’ and slurry piles arising, apparently, from gentle sublimation (Part 7). Then the dykes (Part 8), and the missing slabs (Part 9) -of which there are several more to come- and at least three more as yet unpublished pieces of compelling evidence. That’s eleven more hoops, twenty-one in total to date and counting.

Sorry, twenty-two, I forgot the the original “collisional problem”.

In conclusion, stretch theory answers a multitude of questions that contact binary theory cannot hope to address. Yet on January 8th 2015, the day that AAS 225 closed for business, and astronomers and reporters tweeted views of Seattle en route to the airport, stretch theory had yet to see the light of day.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
Here are the other two photos from part 10:

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2015/01/img_22251.jpg