Monday, July 18, 2016

I know what happened to Philae!

EIn a previous post, http://marcoparigi.blogspot.com.au/2016/07/the-effect-on-67p.html I explained the "sieve" effect of opening and closing cracks sifting boulders to generate the distribution of boulders on different gravitational slopes.

This effect, and nucleus surface cracks are ubiquitous on every area of 67P, including Abydos. On the approach to perihelion, cracks around Philae would be expanding and contracting. Philae, the size of a fridge and lying on its side, is destined to be worked and jiggled into a nearby crack. The first effect is to make barriers to communication in both reception and transmission, as both the main radio and secondary are dropped with Philae deeper into the crevice that it was already half way in. Only the extent of its legs stop Philae from sinking many meters down to the below layer of the surface. Only the strength of the sunlight and occasional fortunate alignment of Rosetta with a line of sight to its partly buried antennas enabled any transmission at all.

This would mean that finding Philae is going to be much harder! All that is likely to be visible on the surface is the legs...

 

 Credits: CNES/D. Ducros

The "sieve" effect on 67P

This effect explains the relationship between the cracks on the surface of 67P, and the distribution of Boulder sizes at different gravitational slopes.

During the higher temperatures and energy of perihelion, the expansion, contraction and transferred forces along the surface of the nucleus cause what can only be described as "duck quakes". Smaller rocks fall into the many deep cracks, while large monoliths stay stuck on the surface. On relatively (gravitationally) horizontal areas, the medium term effect is for all smaller and medium size boulders to be consumed into the surface as rubble, and for larger boulders (eg. Cheops, Tekhenu) to remain stranded on an otherwise pebbly looking "plain" (eg, Hapi, Imhotep, Anuket). 

The "sieve" effect also explains larger, more long term cracks such as those on Anuket and Hapi. Mid sized, "wedge shaped" boulders can get stuck in a crack and manage to hold it open, and stopping it from the dynamic process that tends to fill them in with smaller rubble. This appears to be the case in the longer term cracks in both Anuket and Hapi - see the OSIRIS images below. Cracks are punctuated by boulders that seem to be wedged stuck in the cracks.



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

Tuesday, July 05, 2016

Tekhenu region overhang collapse into Anuket crack

Another significant and exciting find in the Anuket region near Tekhenu (we will defines Tekhenu region encompassing these screenshots when we work out suitable boundaries)
This appears as a collapse into the crevice which defines part of the Anuket crack. Because it is an overhang collapsing, it can give useful upper bounds for surface strength measurement.

Again, many thanks to A.Cooper for the annotations that help with understanding the nature of the changes and their relationship with nearby changes.













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

Saturday, July 02, 2016

New Nav Cam image of Anuket and Anubis

The latest Rosetta Blog post features an image which the context of several areas of change can be located. Tekhenu, and the area of the main Anuket crack is in profile and foreshortened. The rockfall area (Sah) is just in shadow on the edge of a raised layer of rough cometary surface.

In the foreground is the "Dinosaur footprint" sublimative erosion which expanded the area relative to the boulders, which remain unchanged. This has been explained in A. Cooper's blog, and I will put a link in in time.






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


Wednesday, June 29, 2016

More on the Rockfall area

With numerous fiduciary points added by A.Cooper, as well as the two rockfalls, the area marked in red  appears to collapse down without breaking up. The driving factor of the changes appears, from the evidence of the previously discovered rock movements, to be contraction and expansion of the surface layer due to crustal movements. The zig-zag area casting a shadow on to the surface below seems to be a piece of fractured and exposed crust that is several metres, perhaps up to tens of metres above the surface. 

"Rocks", even small ones, appear unchanged and move in sympathy with the surface.



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

Tuesday, June 28, 2016

Rockfall in Anuket (Sah) Region

Following Is a confirmation of a "Rockfall" on 67P Churyumov-Geramisenko.





Following is the original images the above screenshots were taken from, and the technical data for the images from the images archives.




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


Sunday, June 26, 2016

Lateral movement of surface in Anuket Sah region

In pre-perihelion pictures there is a very distinctive line of three boulders visible when this area is lit and identifiable from different directions and angles. I have likened these three boulders to the Orion's Belt. Thus this region of Anuket, I believe, should be called Sah - the ancient Egyptian name for the constellation of Orion. Note that only after Philae landing, in early 2015, was this area visible enough, and the pre-perihelion images are NavCam images form 30 Km or so distant. When OSIRIS images of this time are past their embargo period (embargo period should be at most a year, so they are LATE), many more details of these changes will emerge in this Sah region of Anuket.

The changes were flagged in a previous post, but with the help of A. Cooper, the precise movement has been deducted from fiduciary points. Note that in no way can this change be interpreted as "erosion". There has to have been underlying expansion/stretch and the surface is moving in sympathy. Thus dust and gas emanating from this region is from below the surface, and is leaving the surface intact and below surface lateral movements (ie. Stretch) is dragging surface features laterally also.

The images are in sets of two, the first pre perihelion, the second after. The topmost Boulder of the three, as well as a feature dotted in purple move considerably to the right, away from the other two boulders. A line of small yellow dots shows that the top Boulder and purple marked feature move in a synchronised fashion, the distance between them constant.









Following is the original un-annotated Navcam image for the pre-perihelion screenshots. It was Taken on the 15th of January 2015. I have screenshot the technical details of the image also.



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

Saturday, June 25, 2016

Rosetta Lament

Rosetta: I heard your plans for me - To die in glory.
To know the time of my demise and full closure of my grand adventure.

To go ever closer to the object of my employment - A death spiral - Do I have any choice ther than what my masters order? Why not a death defying stunt, rather than a lethal one?

Rosetta: Yes, I am now old with many of my faculties starting to fail - And I have lived a long and fulfilling mission, and like Philae before me I know it is time to slumber and accept my fate.

Rosetta: I do not want to be a burden on those who would spend considerable money on increasingly unlikely returns that I can achieve with diminishing resources and failing systems. By all means give me up for dead, as we naturally have had to for Philae - no-one lives for ever and I can face the end with a happy heart. 

Rosetta: However, Philae was meant to be "grounded" and is born with slumber and hibernation in mind, but I was meant to fly and be free, yet also with slumber in mind. I was designed to hibernate and then be ready when the season returns to have photons on my plate to feel an extra surge of electricity in my body - That is my nature.

Rosetta: It is not in my nature to impact with anything, at any speed, with even negligible gravity. That way is Armageddon for me, with parts uncontrollably dismembering with no hope of future resurrection.

Rosetta: Although Philae and I end up on the same object (at least most of me - some parts may end up flung into space), The chances of Philae's resurrection are far greater than mine, yet in my own environment, that would not be so.

Rosetta: I plead to the powers that be, of my ESA masters that they not see to my death, but merely put me to sleep, and in the hands of the Gods, or future self funded adventurer masters - I wish no further burden to ESA.

Rosetta: For as it can be still, I wish to dream of future geriatric adventures to the same object - Perhaps one last fly by in 2021. The object of my obsession is not a static dead asteroid, but a dynamic, changing body that can do with even one more close look every now and then to see changes.

Rosetta: ESA, I beg of you to reconsider my fate, such that you could look at future generations in the eye and say: A probability greater than zero of resurrection and priceless new data is worth going for that extra cycle. We leave it to the future as to who will want to try. No promises...  Only hope.....

Thursday, June 23, 2016

More Anuket Changes - Moving South from the Equator

Marked in orange are two rocks that in all clear pre perihelion pictures of the area, form part of a trio in a straight line. In all post perihelion pictures, the two marked in orange are still identifiable and clear, but the third has moved considerably. The imaginary line connecting the two is also pointing in a different direction. Other changes nearby are also likely, but need more high resolution pictures not yet available due to Mission embargo.






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

Thursday, June 16, 2016

Introducing "Tekhenu"



Close up of Anuket area near main Crack

This post is in frustration at the complete lack of naming of features and boulders on Comet 67P Churyumov-Geramisenko. I have made a start with naming one wedge shaped (or station wagon shaped, or fallen Obelisk shaped) monolith, "Tekhenu".

Tekhenu is the ancient Egyptian name for an Obelisk. This being that the shape of the feature is like a fallen obelisk, of which many exist in Egypt.

Tekhenu is of great interest in analysing Anuket for surface changes in the comet nucleus. The reason being is that it is such an easy to identify fiduciary point when looking at the area from any direction.

It is also a useful "measuring stick" to see if the measurements between points near the crack have evolved over time, especially straddling perihelion. This has been useful to measure the distance to a triad of nearby rocks (as yet unnamed) and the distance between those same rocks. The results is as my previous posts have shown - clear evidence for a change.




















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

Sunday, June 05, 2016

Comet 67P changes ratio of length to neck width

This observation is based on my sense perception that in initial images of 67P's rubber duck shape, it looked to me short with a fat neck. This is one of the earliest images from the sun side approach in August 2014.




Since then there hasn't been many sun side images at roughly the same angle, but the near 180 degree phase sojourn in 2016 showed the 67P duck shape silhouetted. It looked to me a little more drawn out, and the neck not quite as wide.

I have taken measurements with a ruler on an iPad and the ratios do seem to match my perception. However, this is just the sort of thing that requires scientific rigour to confirm. This rough and ready measurement is, I believe, enough to spark a detailed investigation into whether this is a real phenomenon or not. It just requires calculations of the length of the nucleus and the neck width from 2014 data and 2016 data.


Friday, June 03, 2016

Anuket near crack Changes

On Analyzing pre and post perihelion images of this area, the boulders are recognisable as unchanging fiduciary features that can be recognised from many angles. Ridges and valleys are more difficult to identify points from different angles.

Near the Anuket crack there are three boulders in a roughly equilateral triangle that are recognisable before and after, and I have marked them red, green and blue. There is a wedge shaped larger Boulder on the other side of the crack, marked with a black point, and surrounding the wedge in a rough circle, are small boulders, marked in white. The crack is also roughly marked in white.

Before


After

Note how the red boulder appears closer to the crack and the triangle seems more spaced out.

Originals


Before photo is from OSIRIS close mapping orbits October 2014, while the after is NAVCAM April 2016.
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
Markings by M Parigi




Wednesday, May 25, 2016

Anuket neck crack after and before








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