Sunday, November 06, 2016

Recombinant Fission in 67P comet nucleus

As suggested in a recent peer reviewed paper:
Hirabayashi et al

Stresses due to "rocking" of the lobes of 67P are likely to cause "fission" - that is a complete separation of the two lobes, but then "reconfiguration" of the two lobes due to their relative velocity being less than escape velocity.

What hasn't yet been considered is that at an instantaneous level, this process is happening repeatedly already! The fractures are causing the two lobes to instantaneously act as separate bodies. Internal frictional forces only then come into play and have a rebalancing effect. The rebalancing is effected by an exchange of angular momentum as the lobes rock relative to each other. Instantaneously fluidised material near the core of the nucleus is attracted outwards by the gravity of the closest lobe rather than the centre of gravity of the entire nucleus. The net effect of this stepwise recombinant fission is that the centres of gravity of the individual lobes move slightly further apart. While the outgassing of the comet is speeding the rotation considerably, the recombinant fission  is effecting a slight braking manoeuvre due to the conservation of angular momentum. 

Friction has the dual effect of damping the precession, and rebalancing the lobes on the neck, a little like a spinning top keeps upright if it can keep spinning. A spinning top has the disadvantage of not having jet "propulsion" and the friction eventually slows a top down to a speed that topples it, while the comet nucleus has a net propulsive torque that keeps the neck balanced even as it gets skinnier due to repeated recombinant fission.

The changes I have found on Anuket are the surface evidence that this recombinant fission is ongoing. The other points of evidence are that there is no torque free precession - implying the damping necessary is evident.

Sunday, October 23, 2016

Timing for Anuket (Sah) collapse. - NOT perihelion

This is an extension of the changes noted in this post:


These changes were thought more likely to have occurred during the time of greatest activity, in mid to late 2015, but the evidence points to a far later collapse.

Image of region in January 2015 

Image in December 2014 for verification of ridge shape:

Image in February (18th) 2016 below: Main rockfall not happened.

Following image shows the Sah area on the February 21st 2016 but angle is not ideal:

Image on March 1st 2016 clearly shows rockfall. 

The conclusion from these images is that the rockfall happened no earlier than 18th of February 2016, and no later than the 1st of March 2016.  OSIRIS WAC and NAC images could narrow this down considerably.

Image Credits
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All lines and dotted annotations by Marco Parigi

Sunday, October 02, 2016

Anuket Sobek Border Confusion

Some aspects of cometary science of 67P are more critical than others regarding accuracy. This is because measurements, maps, feature identification and so forth are shared among many scientists and used as inputs in many papers. Errors, mis-identification and inaccuracies in maps can trickle down and cause problems far into the future for seemingly unrelated papers.

The border of Anuket and Sobek is a case in point. There is a pre to post perihelion change near Anuket's southern border very closely associated with outbursts. There are three almost parallel ridges that look very similar in post perihelion images. These straddle the border, and are also close to the border with Neith. 

However, due to the different latitude of these ridges, most images do not show all three. The ones that do have all three, them in have different lighting angle which means they look different enough in the same image, but are easily confused when in separate images.

As can be seen below, the first map shown is overlaid onto a pre-perihelion image in which the northern most ridge has distinctive pointy overhangs. The border is (correctly, I believe) past the next Southerly ridge which is straighter.

The second map below is overlaid onto a *Post* perihelion image (because they show the southern areas better), but the ridges pointy overhangs have collapsed and the ridge looks like the next southern ridge because the overhang collapses have straightened the ridge. The map is therefore very misleading because it changes the region in which very important outburst have taken place. The highly publicised short outburst lands in Anuket in the top map, but Sobek in the bottom map.

This sort of error can be extremely embarrassing for science, and expensive to fix once papers have used both of the maps separately to come to different conclusions. I think an urgent audit of these maps is in order. It appears peer review has not picked up this and several other discrepancies.

Image Credits
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All lines and dotted annotations by Marco Parigi

Wednesday, September 28, 2016

67P nucleus changes citizens vs scientist

Before and after perihelion images are a great way to verify theories about the connection between outbursts/outgassing/dust flow and the physical evidence of effects on the cometary nucleus surface. Figure 8 from the following paper:

'Are fractured cliffs the source of cometary dust jets? Insights from OSIRIS/Rosetta at 67P/Churyumov-Gerasimenko.'
Vincent, J.-B., et al.

shows a before and after. However, after discussing features *thought* to be fractured cliffs and their detritus, the before and after images show what is *thought* to be evolving flows and *thought* to be partial collapse of a fractured cliff without detritus evidence.

Little effort is made to connect the dots for the reader to try to work out for themselves exactly what is happening and why. I think surface changes are the most fascinating things about comets.


Following is the images and annotations from this blog about a fairly clear overhang collapse.

Further down are the original images for context and for the reader to work out changes/evolution for themselves.


Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:

Wednesday, September 14, 2016

Anuket Crack remodelling

Following is an image of Anuket taken well before perihelion in 2014

Note the triangle of boulders and the shortish shadows.
Also a triangular platform near the main crack.

Following is a July 2016 post perihelion image of the same area in about the same resolution and a similar angle.Shadows are a bit longer. Changes are quite obvious. Boulders have moved, The triangular platform near the main crack has collapsed.
 These are videos overlaid to help see the changes trans perihelion. One is slow, and one is fast.




Sunday, September 11, 2016

Hallelujah - Philae's been found

Hallelujah - Philae's been found.
The comet landing space probe lost 
Years ago when it went to ground,
Into a shadowy nook tossed.
Out of the sun, it went to sleep.
Mother ship Rosetta searched on.
But from Philae, nary a peep.
Where could the little probe have gone?
Rosetta found the little one,
And sent the good news back to Earth.
Some needed closure thus was done
For the mission - for what it's worth.

Philae with Rosetta in flight,
Cometing into the dark night.

Friday, September 09, 2016

Abydos Orientation

See images to work out what you are looking at and the area of Abydos from many different angles, lighting and magnification.

Colours are an attempt to identify features such as perihelion cliff here, marked in green and orange roughly where I think they are on the Navcam and OSIRIS images below.

Magenta is approximated Philae position. Blue is a prominent egg shaped boulder for reference.

White Quadrangle is roughly the area bounded by the Philae discovery image second image below.


Image Credits
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All lines and dotted annotations by Marco Parigi

Thursday, September 01, 2016

Here's Philae - I have found him

The wider Picture: Follows are OSIRIS images, first pre-landing - Philae not in this one.

Next two - Post landing - Philae is now visible and perihelion cliff can be identified.

Perihelion cliff marked from CIVA image

Perihelion cliff marked with small red and green dots, from Pre-landing close up of the area.

Follows are recent July 2016 NAVCAM images with a distinct glint (saturates pixel) in exactly the same location identified above.

Second July 2016 NAVCAM image shows same glint in same location - therefore not an artefact.
Following is close ups of the above - The tell tale glint from Philae in the centre of images.

There are several other images not listed here that also show Philae, but this is the location that the ESA will soon announce with much fanfare as a conclusive location for Philae. Close OSIRIS images from 5 km from the surface should now resolve any parts of Philae that may be exposed showing this glint. It could be as little as a foot or leg.

Image Credits
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All lines and dotted annotations by Marco Parigi

Thursday, August 25, 2016

Animated gif's for the boulder movement in Anuket

If anyone is still convinced that there is no movement of boulders in Anuket's trio, have a look at the following link:

Moving boulder link

There are several Gif overlays of pre and post perihelion images at the same scale and close to identical angle. enjoy...

Monday, August 22, 2016

Profile of a Processed Comet

Recent papers based on evidence discovered on 67P by Rosetta, are trying to shoehorn evidence into alternative primordial or otherwise formation narratives. However, if the comet is actually a highly processed object, none of the visible evidence can have anything to do with primordial processes.

I have used their many lines of evidence summarised in a diagram, as evidence that the comet is processed, and that therefore the whole narratives are speculative and evidence free from the perspective of what Rosetta is studying.

Click for high resolution image:

Comets are the most processed objects in the solar system...

Sunday, August 21, 2016

Andrew Cooper's confirmation of Boulder movements at Anuket

This post has been reblogged for convenience here as a hugely detailed explanation of precisely the changes that I had detected back in May and June 2016 from freely available published images.

This is the post I made when I became 100% convinced of the change:

Of course, I realise I hadn't explained it well, and in some ways it seemed obvious, but the following blog post is rich in detail, explanatory notes and close images from varying angles. I challenge anyone to make a counter claim on what is happening on Anuket.

Reblogged from


AFTER- the red dot has moved. Old position marked with a smaller dot. Please ignore the red smudges below the green line.

Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
(All photos are from the NAVCAM except one OSIRIS photo which is credited inline. Full credits at bottom).
In June 2016, Marco Parigi published a blog post in which he suggested that a boulder on Anuket appeared to have moved. Here’s the post.
Whilst the apparent movement looked real and compelling, the various photos of the Anuket neck that I’d seen so far didn’t show enough detail for a detailed analysis. They needed to show the boulder actually sitting on one side of a small, local feature in one photo and then sitting on the opposite side of that feature in a later photo. The feature, whatever it might be (a small crack or ridge or discolouration) would then be acting as a reference point or fiduciary point to betray the boulder’s movement.
Recently, I was browsing another of Marco’s posts on a related change close to the boulder in question. I realised that the photos in that post had sufficient detail to look for fiduciary points that the boulder had slid past. Here’s that post, from which the photos further below were culled.
The two photos from the link above are the two main photos used in this post. Others are added further down for extra evidence.
Photos 1 and 2- the triangle of boulders. Originals are included where appropriate but not included in the numbering system.

Red- Marco’s boulder that was suggested as having moved. Smudged red is an old artefact. Please ignore.
Light blue- the other two boulders that could be considered to be the base of the triangle. That base stayed the same width but as the triangle appeared to elongate due to the red boulder movement, the base went from looking fairly wide to being comparatively narrow when compared with the height of the triangle.
Photos 3 and 4- photo 3 shows the position of the red boulder before the movement. Photo 4 shows it after the movement. These are the header photos, reproduced.

Red- the boulder. Also, in the after photo, the tiny red dot above the actual boulder shows its original location as in the before photo.
Yellow- a slightly curved feature which leads up to the base of the red boulder before it moves and is marooned above the boulder after it’s moved. This is proof that the red boulder did indeed move.
Orange- a distinctive ‘W’ shape that’s visible in both photos. It’s useful as a a general fiduciary point. It can then be seen that the yellow feature branches off one end of the W in both the before and after photos. You need to look at the unannotated versions to see the W once the dots have shown you where to look for it.
Green- this traces the line of a distinctive quasi-triangular feature, part of which collapsed into the main Anuket crack between the before and after pictures. That collapse was documented by Marco in the second blog post linked above. You can see that in the before picture, the red boulder is some distance from the apex of the green triangle. In the after picture, the red boulder is almost kissing the apex. This, along with the marooned yellow feature proves that the red boulder did move.
Photo 5- this is the same as photo 3 but with a single added tiny red dot. This shows the location to which the red boulder would subsequently move.

The lighting in the before photo is similar to that in the after photo. This always makes comparison between features somewhat easier. However, in this case it allows us to check the length of the shadow cast by the red boulder in each case. If we then identify the position of the tip of the shadow for the after shot we can go to the before shot and annotate a shadow from the red boulder in that shot all the way to the known shadow tip in the after shot.
The reasoning here is that if the comet is static and nothing moved, the boulder/shadow geometry for the after shot would be the same as for the lighting-manipulated before shot. It stands to reason that if the after shot lighting angle is faithfully reconstructed in the before shot, the shadow tip of the red boulder absolutely has to reach the same spot in both cases. So our annotated before shot simply assumes the same lighting angle that pertained in the after shot and casts the drawn shadow to the apex that it would definitely reach under the same lighting conditions as the after shot. The result is a ridiculously long shadow, well over twice as long as it should be. So that proves the red boulder moved too. The shadow reconstruction photos follow.
Photos 6 and 7- the red boulder and its shadow (6 is the before shot).

Red- the two sides of the boulder in both cases. The side in shadow is estimated. It may be argued that it would be better to measure the visible width and compare it to the shadow length instead but it just so happens that the distance between the red dots is the same as the width at its widest point and this is the case in both photos. So both methods apply with the boulder/shadow ratios we’re about to calculate.
Yellow- the shadow tip.
The ratio of shadow to boulder is 1.82 for the before shot and 1.58 for the after shot. There’s obviously an error margin involved but they are both certainly well under a ratio of 2.
Photo 8- identifying the tip of the shadow in the after shot (yellow dot).

Photo 9- transposing the shadow tip location for the after shot to the before shot (yellow dot).

Photo 10- this is the annotated shadow set-up. The set-up assumes the red boulder never moved and that it’s lit from exactly the same angle as for the after shot. These two assumptions have to result in the shadow reaching the location of the yellow dot. The shadow is annotated accordingly. The ratio of shadow to boulder is 4.16. That’s well over double what it should be, in fact 2.63 times more than the after shot ratio of 1.58. You can see that even the (real) 1.82 ratio shadow in the photo is dwarfed by the ludicrously long annotation.

This anomaly is very difficult to explain for a boulder that never moved. The obvious solution for obtaining anything near the required 1.58 ratio is to give the boulder a very noticeable shunt to the left.
This happens quite often when looking in detail at one particular phenomenon. You suddenly realise something else nearby has also torn, slid, delaminated or collapsed. The right hand light blue boulder also slid (or rolled).
Interestingly, it slid up the neck in the opposite direction to the red boulder.
Photos 11 and 12- the blue boulder slide.

Light blue- the sliding boulder.
Bright green- three dots next to the light blue boulder. These denote an actual line that runs at 90° to the base of the ‘W’. You can see that the blue boulder is below the line in the before shot and above it in the after shot. Please look at the originals to confirm this. The bright green line is obvious and the boulder movement unequivocal but the dots obscure the line itself.

Photos 13 and 14
There has been a suggestion in the comments on the Rosetta blog that the red boulder might be sitting at the top of a slope so that parallax alone accounts for what is actually just apparent movement. At a low-profile angle and looking from below (as in some of these photos) it would then appear to be closer to its light blue twins than it really is. As you rise up the neck to look vertically down at 90° to the surface, the parallax element would not take effect and the full distance between red and blue would be betrayed. The difference in the two cases would amount to apparent movement of the red boulder.
The detailed analysis above proves that the two boulders moved anyway, whether such a slope exists or not but it’s as well to address the issue here so that it’s laid to rest.
The simple solution to establish whether there is indeed such a slope is to look at the area from the side and from low down. If it’s there it will be shown up in full. The two photos below show that no such slope exists. Photo 13 is a before shot and photo 14 is an after shot. The before shot has the boulder triangle annotated because it’s so faint and the nearer blue boulder is as good as whited out. Seeing as these are both essentially side views, flat and with no parallax slopes it’s quite clear that the red boulder has moved. The movement is evidenced in the the spaced-out triangle.
That sub-heading is a quote from Marco’s original post on the boulder, the one that’s linked above. Time and again in the course of working out what the 67P morphology is telling us, we notice something that looks odd but can’t state quite why it looks odd. We might pass over it dozens of times on the way somewhere else, scratching our heads every time, remembering that the paradox is as yet unresolved.
In this case it was the fact that “the triangle seems more spaced out” and yet the degree of movement of the red boulder didn’t seem to warrant it being quite that spaced out. Then, whilst annotating the photos for this post, the paradox was automatically resolved. The triangle is now more spaced out because the top-right boulder moved upwards. That’s why the triangle is now so long and thin.
The two light blue boulders remained essentially the same distance apart while the right hand one moved up. Since they constitute the short base of the triangle, the base remained the same width but shunted back a bit on one side. Combining that with the red boulder extending the long tip explains the spaced out triangle.
And, more importantly, we now have two boulders that have moved and they’ve moved in opposite directions: straight up and straight down the neck.
Since you should now be more familiar with the fiduciary points, these two photos are, for the most part, left unannotated. However the two closest zoom components each have an annotated version. The annotations are the same colours as for the header (reproduced with their key in photos 3 and 4). There are eight photos, four versions of each as follows: original, medium zoom, close zoom, close zoom annotated. They’re presented in pairs for comparison of course.
Photos 15-22



The reason for the movement of the two boulders and the fact they have moved in opposite directions will probably get its own post when other evidence avails itself, as it usually does. However, as a prelude to such an analysis, one possible reason for the red boulder moving down the neck is the subsidence of material into the neck crack only a short distance away. That’s described in the second link above and it’s placed here as well for convenience:
It would be odd if the two events, collapse and boulder movement, were unrelated when in such close proximity and while such little change has been noticed elsewhere on the comet (notwithstanding Marco’s other Anuket neck change discoveries and the Imhotep slump). It could be argued that the collapse into the crack, being only 100 metres or so away, caused a slight trough between that apex of the subsided material and the boulder, enough for it to affect the gravity gradient and allow the boulder to slide or roll in that direction.
Slumping in any situation is prone to cause sympathetic ground movement around the slump. Indeed there is some indication in the photos of a slight trough in the after photos but it’s to the right of the slide track and could be the lighting anyway. We await the OSIRIS after photos.
As for the blue rock moving up the neck, there are delaminations in that direction as a result of stretch. The boulder triangle is sitting right next to the ‘orange tell-tale line’, after all. That line is itself a one-kilometre-long delamination from head rim to body (Part 25 of this blog).
Another reason for citing delaminations is this. That orange ‘W’ in the pictures above was just a random feature in my mind until I realised that there was a boulder placed neatly at each end and one in the middle. One boulder for each apex. We already know from experience that delaminations often leave boulders behind as they shunt away from a particular position. They tend to shed talus from obviously ragged cliffs (see Part 50) and chunky boulders from squared-off cliffs (e.g. the Hapi boulders and the three Aker boulders).
The W is very blocky or you might say, squared off, and there are chunky boulders right next to it as if related to it. The knowledge of blocky cliffs shedding large boulders, derived only from stretch theory, prompted me to hunt for another W without even knowing whether one existed at all.
Stretch theory also told me where to look: one or two hundred metres up the neck, possibly with a circa 45° southerly bias. The upward component is due to the obvious neck stretch vector (Part 25). The southerly bias is because everything was delaminating along the shear line and around the soon-to-be head rim just before head shear. Those delaminations have been identified (not blogged yet but tweeted). The combination of southerly delamination before head shear and easterly (up the neck) delamination during neck stretch results in a circa 45° vector-summed resultant direction. So that’s where I looked first. And sure enough, there it was:

Photo 23
That’s the predictive power of stretch theory and it’s why the boulders got left behind in that ‘W matches the boulder triad’ configuration.
Photo 24- the same as photo 23 but with the boulder dots depicting the triangle in the ‘before’ configuration.

This shows how closely related they are to the W. Notice how the right hand end of the newly found W turns 90° to form a chunky rectangle just like its classic twin (whose rectangle is more visible in the header).
This part puts to rest any doubts that Marco Parigi’s boulders moved. His discovery in the first link above is therefore the first documented account of moving boulders on 67P/Churyumov-Gerasimenko.
Copyright ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0
To view a copy of this licence please visit:
All dotted annotations by Andrew Cooper