To give a clear point of view I am not a friend of leaked data, but I was also mesmerized by this statement. If the data already leaked, and if this statement is published in such a public place, everyone should have a chance to see them. I also tried to find them, with only little success.
If you do a Google image search with: Philae, Rolis, and image size 261x136 pixel you may find one of the images that is probably meant. Don't expect too much, the original ROLIS image once released will probably show much more. It seems to be an analysis of one of the footprints that Philae did on its final landing site.

I am really eager to see the official release of the ROLIS data in original resolution!

I went through the available Navcam and Osiris images, and the one that for my eye best explaines the possible location and situation of Philae is the Navcam mosaic "Comet_on_14_September_2014". After including the possible diamond shaped landing area after CONSERT triangulation (blue diamond) there are several possible places that are consistent with the information that Philae only gets 1.5 hours of sun per Chury-day (green markers). It is only a very rough analysis. As I see it, all possible places have in common, that the situation should really improve in the next months with the sun more to the south. North is roughly up in this image.
Philae was a full success up to now, congratulations to the Philae team, the Rosetta team and the teams with experiments on Philae!
But perhaps the Philae story is still not over now... and if it is really possible to wake up Philae again, perhaps his position will ensure an even longer life than predicted, with less sun heating up the surrounding area - perhaps even surviving the perihelion?



Image: ESA/Rosetta/NAVCAM, CC BY-SA IGO 3.0

Video Animation: Descend to Titan

At long last, a digest of my rendered video animation "Descend to Titan" made it to my website:
http://www.beugungsbild.de/huygens/huygens.html

--René

tfisher: Very interesting, and nice work! I have not considered this location up to now, but it looks plausible - including the cat scratches!



Where did you find these Ta and Tb raw images? I could not find them at the Cassini- or the ISS-website.

Sorry for me answering so rarely, I have very little time at the moment, but I am following this dicussion with great interest!

--René

I am not an expert concerning the projection methods, but to follow the classification used by these two ESA image products:
In stereographic Projection:
http://saturn.jpl.nasa.gov/multimedia/imag...fm?imageID=1527
and in gnomonic projection:
http://saturn.jpl.nasa.gov/multimedia/imag...fm?imageID=1528

my mosaics are all displayed in gnomonic projection.
Only the fisheye view:
http://www.beugungsbild.de/huygens/povray/Titan_fisheye.jpg
is rendered in stereographic projection.

Up to now I only knew these different projection methods for projecting curved surfaces to a plane. But that is not the problem with Huygens images, since the imaged area is so small that it can be assumed as being flat, the errors in stitching the images will be much larger.
This stereographic method (or fisheye view as I call it) is a nice method combining HRI, MRI and SLI images. Using the gnomonic projection method for the mosaic, as I did, has the disadvantage, that the images with the worst resolution and contrast at the rim are displayed with largest magnification. But you can directly compare them with the Cassini images after scaling them. You can read them like a topographical map (without topography included of course)
The position of the two black lines in my mosaic should be not too far away from the truth - such a large difference that it could be the two lines in the radar swath with one of the mosaic positions suggested up to now is not possible I think. You can check that by yourselve, one line (and a little bit of the second) is even visible in one of the MRI images (Nr.280):
http://www.beugungsbild.de/huygens/huygens_mosaic.html
and from geometrical considerations (Position of Huygens during that imaging sequence) it is not possible that these two lines are so much farther away that they could correspond with the two cat scratches from radar. Only if the position (or size) of the mosaic would change this could could be considered again.

--René

The two dark lines in the Huygens mosaic are real, I am rather shure about that, they can be seen in several SLI raw images: (better have a look at the panorama at the bottom; and may be the images 470 and 440 should have a somewhat larger overlap):
http://www.beugungsbild.de/huygens/huygens_distant_view.html

But I don’t think that the two cat scratches from the radar image are the two dark lines Huygens saw. If that would be the same two dark lines visible in the Huygens mosaic and panorama, we would have to think about a size calibration error again. With my old positioning that assumed a calibration misfit of a factor of 2.5, the two cat scratches should have been close to that position where they are now. But there are cat scratches (dunes) in many places, all running in west-east direction. I think the two lines visible in the Huygens images are invisible in the radar data, perhaps because they would be located close to the seam where details are less clear.

--René

I figured out this position of the ISS image to the radar swath data. It would mean that, if the Huygens landing site is indeed the eastermost tip of Adiri, it is perhaps not or not completely included in the radar swath, or am I wrong?

Thank you, Jason!!!

Looks as if it would not be so easy to position the Huygens mosaic within the radar map...
Is it possible to get the radar map of the Huygens landing site without the mosaic inset?

--René

So, if I understand it right, my orientation is correct (north up) in that image?
The blue arrow only marks the brightening of the horizon I was talking about, it does not mean the north direction. North is simply up. I should have mentioned that, was perhaps a little bit misleading, on my Homepage I also included a marker for north (bottom of that page):
http://www.beugungsbild.de/huygens/ISS_huy...correlate3.html

You are right, in many images the visibility of some details can be improved by a low pass filter. But it is often difficult to estimate what is detail and what is noise, so I decided to use the images without filtering them. I know that applying a filter now on the mosaic is more difficult than filtering each image alone, because the images at the rim are increased in size with respect to the inner ones. But if I had filtered the images before it would be irreversible. Now you can define several areas in the mosaic and filter each with an appropriate low pass adjustment. It is on my list, (and has been there for some time) like so many things...

--René

Mosaic North-direction

During my last attempts to find possible positions for the Huygens mosaic within the Cassini images for the upcoming flyby, I realized that the information regarding the correct north-direction was perhaps hidden in one of my early panoramas all the time, but I did not realize it...
The slightly brighter horizon around the images 476, 400, 526, 446, 380, 455 of the panorama "Huygens distant view" (blue arrow) marks the direction opposite to the sun! Backscatter in the atmosphere results in a brightening of the haze around that point. I do not think that it is an artifact, since it can also be well seen as an inclined horizon brightness when looking at the SLI raw images, the
numbers 476, 455 and 400 for instance.
With the information where Huygens approximately was when shooting the corresponding images (green ellipse) the sun direction can be determined with an uncertainty of perhaps +-3 degrees (the two red lines in the upper left). The resulting rotational orientation (north direction) very well fits the new orientation reported recently, by Larry Soderblom for instance.
And I did not see it...




http://www.beugungsbild.de/huygens/huygens_distant_view.html

It was very valuable to mention it again, Alan. I read it in Emily Lakdawalla's weblog, but somehow I lost sight of that information. I was also told by a friend who visited the DPS conference and heard Larry Soderblom's talk. If I am informed correctly, the direction information now was gatherded by using the variable field strenght of the transmitter signal of Huygens, that did not have a rotational symmetric characteristic, and correlating that with the image that was taken a moment before. So for every image there is a direction information that is independent from the sun sensor.
With that new orientation, the best fit should be as in the image below. This analogy still is not sooo good, but it is better than in my previous attempt.
Placing it perhaps 40km northwest of that position may also be possible (on top of that pale triangular formation), but I think the Huygens landing site would be too far off from the position that was calculated.



One should also keep in mind that it is very difficult to make a correct large scale albedo adjustment in the mosaics. I am quite sure that north of the bright "highland" there is a somewhat darker area, resulting in this triangular shape of the highland region, but it may well be that my photometric correction leaves it slightly darker than it is in reality.

--René

One of the most exciting questions for me is, if the radar swath data will result in a definite decision how the Huygens mosaic and Cassini ISS/VIMS correlate.
Some month ago I tried to find this correlation, with the result that I felt I had to introduce a relatively large calibration mismatch to find a good visual agreement of Huygens and ISS. But now it has come to my knowledge that Huygens radar, as well as radar tracking of Huygens from earth, seems to be in good agreement with the timer height calibration, so it looks as I have to give up this idea.
http://www.beugungsbild.de/huygens/ISS_huy...correlate3.html

Does anybody know what radar resolution is expected at the Huygens landing site?
Will ISS also obtain some high resolution images?

--René

I suppose that, if this model is correct, the silicate-rich dry crust should have a consistency of fine, low density sand, while the original material should have a consistency perhaps like foamingly frozen clay.
A meteorite, especially impacting into the low density powdery crust, but also in the low density original material, would explode (explosively evaporate) very deep below the surface. This creates a steep, cone-shaped crater, as discussed for "Deep Impact".
Later landslide may occur on the crater walls, also leaving a cone-shaped crater with less steeper crater walls.
There should be a smooth transition between the "frozen clay" and the "dry sand" consistency with decreasing frozen water content, somewhere in between the material should have a low ice content, but with just enough ice between the grains to glue them together and prevent landsliding of the steep walls. With the ice content further decreasing the landslides start.

--René

A Model for Hyperion

For a better understanding concerning my model for Hyperion's appearance regarding the dark crater bottoms I made some diagrams.
Please note that this is not based on any official statement, so it should not been taken as an official explanation of what we see on Hyperion. This is solely my personal attempt of an explanation of the processes that may alter Hyperion's surface.
The conical shape of the craters or landslide effects are neglected in the drawings



Fig.1:
The original material of Hyperion is a porous, dark mixture of silicates (from dust to rocks), frozen water, and all the other components that are typical for a relatively primordial body of the solar system like carbon dioxide, methane, ammonia and other. Due to warming by the sun, perhaps supported my micrometeorite bombardment or by internal heating resulting from Saturn's gravitational influence, the water and the other volatile components slowly evaporate or sublimate.
This process leaves behind a brighter layer of silicate rich dust and rocks that covers the surface of Hyperion.

Fig.2:
The evaporation rate slightly decreases with growing layer thickness, but it does not stop, since the porosity of the layer still allows the volatile components to reach the surface. The timescale for this process is at least some million years.

Fig.3:
If a meteor crater is deep enough to reach down into the native material, we see this appearance that is typical for Hyperion, with the dark, water-rich material from below exposed at its bottom.
The crater floor will slowly develop a bright surface again, since the evaporation or sublimation should be increased if the layer of silicate dust is missing. On the other hand, the evaporation or sublimation rate may be reduced at the crater floor due to the originally porous material being compacted by the pressure and heat of the impact.

Fig.4:
Small craters within the dark material are also dark when they are young but...

Fig.5:
...the increased surface to volume ratio of protruding structures like the rim or the central hill speed up the loss of water. These structures become bright much faster than the surrounding terrain.

Fig.6:
After a sufficient time the complete crater is bright again. The thickness of the bright layer for a long time remains thinner than at the older surface. This may be the reason, why in this large impact basin more and smaller craters seem to have a dark floor than elsewhere.

--René

At first glance there seem to be similarities, since Callisto also has these bright crater rims. But at Callisto you can see that all the terrain without a steep slope is covered with the dark stuff, while on Hyperion most of the flat terrain shows no trace of it, if it is not a crater bottom. I can't imagine how it should get there without leaving a trace anywhere else, especially a trace of sliding down the crater walls.

--René

Excellent work!!!
On Wikipedia there is an article about Hyperion with a colorized (?) Voyager image that is said to show the real color - I do not know how correct it is, but then Hyperion should be somewhat more red. Perhaps you can find the origin of this information.
--René

Sorry, my last answer was perhaps verbalized a little bit sloppy and therefore misleading:
I meant the impression concerning the landslides.
Concerning the crater wall steepness, as I already wrote as an answer to Jason's "thought for the day", my impression is as follows:
Compared to Phoebe for instance, the craters are not much steeper, but compared to other much larger (more solid?) moons many craters are really very steep, and the walls very often have this typical conical shape that can be found on Phoebe too.
--René

Your impression may be correct, in many craters there seem to be landslides visible that have buried the dark floor partially or completely. But I cannot see features that piont to any sliding of the dark material. Looking at the landslides it seems to my that the bright material should have a consistency of dry sand.

--René

Concerning all the models that assume accumulation of the dark stuff from above I see many discrepancies with the Cassini high res images.
At first, a layer of material should exhibit many spots were meteorite impacts blasted away the layer, leaving a bright spot behind. Beyound the hundreds of craters visible I could not find a single crater within the dark stuff that looks this way. An inspection of the general process of crater formation shows that at least the center of a crater exposes material from beneath. The center of the small craters would have to be bright if the dark stuff was just a thin layer.
On the other hand one could assume that nearly all craters are older than the layer, but then there would be new discrepancies: if the material falls in from space, one has to explain why there are so many craters without any trace of the black stuff.
Assuming it is material that slides down the walls of the large craters after its icy component has disappeared, we have to explain why we do not see the small craters or other structures within the large craters to hinder the material sliding down. Below these small craters a fan shaped area should be visible where less material is present because it has to flow around the protruding structures (see the drawing for discussion, the red circle symbolizes a crater with the expected fan shaped area below drawn into the image).

On Phoebe I am quite shure that we can see dark material sliding down the steep slopes and exposing a bright layer (ice?) below, it looks exactly as one would expect it to look, but comparing this with Hyperion I think that there must be a different origin for the dark crater floors on Hyperion.

--René

Very nice mosaics, congratulations!

When looking at the original images we can sometimes see that the dark crater floors are not as dark as the shadow zones in the craters. Would it be possible to preserve this difference in the mosaic by a slightly weaker contrast, so that details of the dark crater floors are still visible? Or do too many of the original images already have a contrast that is too high?

--René

My impression is, that the craters are not unusually deep (or steep), compared with Phoebe for instance, but the craters are more often funnel shaped (as on Phoebe too) than the typical bowl shape when compared with a larger, (more solid?) moon. One can find also a lot of shallow craters on Hyperion, and for me it does not look as if a dark crater floor is correlated with the slope of the walls.

For a good impression of the true brighness contrast between the dark and the bright material this image may be useful:
http://saturn.jpl.nasa.gov/multimedia/imag...eiImageID=50265

It shows the dark stuff in sunlight, as well as the total darkness of the shadows. With the help of this image I estimated the albedo of the dark material being about 40-50% of the albedo of the bright material.
One crater above the center has the shadow on its bright, as well as on its dark region. Concerning the shape of the shadow, there seems to be no significant difference in slope between the two zones for this particular crater.

-- René

I can only agree, this was also my impression, while I don't think it is exactly like this.
What is also striking, and not so easy to explain is, that most of the craters in the dark material have a more or less bright rim that lets them appear like rings, and you can only find very few craters that are completely dark.
But perhaps I have an idea for a model. What about the possibility, that the dark material has a high amount of volatile components (frozen water, hydrocarbons), and after evaporation or sublimation the bright stuff remains. This seems to be the other way round than we expect it (we expect ice to be bright), but ice mixed with other fine grained stuff in most cases is darker than the same stuff alone.
Originally Hyperion was dark, but due to evaporation or sublimation of water and the other volatile components the bright loose crust formed. This evaporation process continues even through the low density crust, that very slowly grows in thickness on the cost of the dark core. If a meteorite strikes the surface, the original dark material is exposed again, the evaporation is increased at that place, and after some million years the crater floor is bright again.
But why should the rims of the small craters be bright? This model could explain it very easily: Any structure protruding above the original plain has a higher surface- to volume-ratio and would "dry out" faster than the surrounding flat floor. The fact that the rim is made of shattered material should support this process. The small craters that are completely dark would then be the youngest craters of all craters existing in the dark material.
If this is true, Hyperion would indeed be very close to a comet's nucleus.

--René

The images of Hyperion are fascinating, and its appearance with the many dark crater bottoms and the very steep crater walls seems to be unique, never seen on any other Solar System body before (?). For this reason I wanted to start a special topic solely about Hyperion and the origin of its appearance here.
(By the way: phantastic mosaics and color images, Jason!)

In most discussions here I have read the idea, that the dark crater bottoms is material that slides down the steep crater walls after the volatile icy component has evaporated or sublimated away. But looking at the many images I could not find a single (small or large) crater in the dark material that would expose bright material beneath. Shouldn't we expect this? If the dark component would indeed be a more or less thin layer deposited on the crater bottoms one should find many small craters were this thin layer was blasted away by the impact.
Because of this, my impression is that the dark stuff is the material from inside Hyperion, exposed by impacts, and the bright material is the crust.