There weren't any color filters on Huygens' camera -- it was monochrome. The "color" image was made using information from one upward looking and one downward looking color sensor, so the color is just a wash applied across the image.

Please remember that Huygens wasn't necessarily expected to survive its landing; and that the designers had no idea whether it would smash into a solid surface or splash into liquid or mud. If one of the latter occurred, the camera would have been under the surface and wouldn't have seen anything at all! It wouldn't have been responsible to increase the complexity of that particular instrument to take lots of pictures at a stage of the mission that the designers weren't even expecting to see.

--Emily

.. or land on a rock and break, or land in a canyon with the line-of-sight to the orbiter relay blocked, or
land in foofoo dust that swallowed the probe up.... None of this could be ruled out

It might be possible to design engineering solutions to any of these, but not for all of them, and not for
a finite cost. Remember also that the long surface operation only became feasible after the 1992
descope (which forced the relay to use the High Gain Antenna, which meant from further away,
rather than near a close, closest approach....) by which time the camera and everything else had been
designed - the original plan guaranteed only 3 minutes of visibility post-impact.

The camera was only I think the 3rd CCD flown on a planetary mission (Giotto being the first, tho
Galileo's was built first....) Huygens' modest datalink meant a camera was marginal anyway (note
Pioneer Venus, Galileo didnt have one) and the rather nifty german DCT hardware data
compression (sort-of-JPG) - which produced all those artifacts you guys dont like - was essential to
making a camera viable at all.

Just to be picky, as far as framing CCDs go, the Vegas and Phobos-2 (and 1, for that matter) carried them as well.

Have to agree with Emily here.

As frustrating as it is for some us to thnk about what might have been done to augment the instrumentation and data (I have been guilty of that myself), we all are extremely lucky to have the data that we did get from the surface. HUYGENS had a limited budget, and the design was frozen well before anyone had a good idea of what the surface would be like. And HUYGENS was meant to be a probe of the atmosphere with DISR helping to understand the surface from the float down through the thick, cold, air.

Heck.... originally, no one expected the ISS or the VIMS to be able to sense the surface.

There are indeed transient events visible in the surface images but they are just at the edge of what can be confidently garnered from the data.

Tantalizing us with hints of ???? .... but then Titan is great at tantalizing us.

Its wonderful.

Craig

Ah thanks. Forgot about those, making myself guilty of what I often complain about...
(btw it is always an uphill struggle fighting with press people
who always want superlatives - Cassini is/was the most massive planetary spacecraft launched
*in the west* (Phobos being larger))

So Huygens was 5th (or 7th if you count cloned s/c separately) planetary CCD

I remember being very excited in the lab at the University of Surrey (now the operation is
Surrey Satellite technology Limited) as an undergrad in 1989 getting my picture taken by the
camera on UoSAT-4 during bench-testing.... it was one of these new-fangled CCD things

To be more precise, the camera was broadband, sensitive over a wavelength range from roughly 600 to 1000 nm. The first color image released was indeed colorized, using a single color derived from a spectrum taken just before landing by DISR's Downward Looking Visual Spectrometer (DLVS), in which reflected lamp light was not present. The first color image released was too yellow; the "true color" as would be perceived by the human eye on the surface is more likely deep orange. Since the DLVS was not sensitive to blue, the real "true color" cannot be retrieved, although (broadband) Downward Looking Violet Photometer (DLV) data can help here. Anyway, hardly any blue light penetrates the haze to reach the surface.

Stefan.

True - my only complaint is that the range of possible/expected scenarios was a little too tight.

A follow-on mission must be capable of a broader range of chemical forensics.

Thanks Doug. It's 58,59,62 and 63 from this one and 458 onward from 'huygens news thread' for a start. I'll check the T36 thread now and post back.

Just post 14 from T36 thread should be moved to the new thread. It would be nice to have the two T36 ISS mosaics, Gordan's and the other one as well, but I don't think they should be removed from the pure T36 thread.

The November 2007 issue of Planetary and Space Science is being offered freely online:
http://www.sciencedirect.com/science/journal/00320633

This particular issue is a special issue on Huygens.

Quite a bit of interesting reading I'm just starting to look at - thanks for the post. The Soderblom et al paper (pages 2025-2036) discusses how the correlation of bright and dark areas varies between the VIMS and SAR views. Markings are much better correlated just east of the Huygens landing site compared with the western portion of the region.

Latest CHARM

Results from the Descent Imager/Spectral Radiometer (DISR) Experiment on Huygens

http://saturn.jpl.nasa.gov/multimedia/prod...ARM_Tomasko.pdf

An article in press has Huygens Landing site from DISR analysis:

Keller, H.U., Greiger, B., Kuppers, M., Schroder, S.E., Skorov, Y.V., Tomasko, M.G., Planetary and Space Science (2007). “The Properties of Titan’s surface at the Huygens landing site from DISR observations.” doi: 10.1016/j.psss.20007.11.020

(Pay for article: Abstract available here)

Their interpretation of Huygens’ {note apostrophe placement} images of streambeds on the bright island differs from that of the Soderblom et al. article.

In the Soderblom et al. article, the authors contend that dark material coats the streambeds [either bright stuff removed from erosion, or dark stuff leached from bright material coating the surrounding lands].

In contrast (!), Keller et al. hypothesize that topographic shading alone can account for the darkened channels. From their analysis, “the darkest pixels in the bright area [bright area is the island] are considerably brighter than the darkest pixels in the dark area [dark area = channel floor]. Their interpretation is that the island is uniformly coated in bright material and only shadowing (from semi-diffuse light) makes it appear dark: “the darkness of the river beds can be explained by topographic shading, without the need for dark deposits.”



On the way down, two spectral maps were acquired (these are the cool-o little flower patterns made in the bells and whistles descent movie). One was taken at 18 km altitude (SM1) and one was taken at 4 km altitude (SM2). The 18km spectal map (SM1) crossed over the island, the channel (and spooky dude formation) and the SE channel shore (putative rotten terrain) and then back across the channel again. The 4 km spectral map covered most of the dark channel and just hit a little of the spooky dude formation – it is pretty much pure channel and can be used to guage the uniformity of the channel terrain.

The authors describe the interpretation of these spectal maps in great detail (with some great images showing spectral ratios). The authors use brightness ratios at certain wavelengths to demonstrate that the bright island terrain is spectrally different from the dark channel terrain.

From the spectral maps, the authors show that the channel bed spectra becomes more “island-like” the closer you get to the island, indicating that stuff was washed in from the island into the channel. A separate analysis shows that brightness is stepped (terraced) into the channel depths.

[IMHO both are consistent with from laminar flow along the channel reworking washed in sediments from the island]

The authors also state “since we expect that aerosol deposition should cover the surface within a few decades, the fact that these color differences exist indicate that fluvial or Aeolian process creates or maintains them.”

[IMHO there’s an alternative explanation: aerosol deposition doesn’t happen in the equatorial regions very much, most of it happens in high rainfall areas like the temperate or polar regions]

If I interpreted the figures correctly, one thing that I found fascinating in their data is that the spooky dude formation (brighter by DISR) did not match spectrally with the bright Huygens island terrain or the putative “rotten terrain” on the SE shore. It seems to fit in with channel material, or at least it’s variations are similar to what you would see for channel material.

This is consistent with my pet theory that the the spooky dude formation is channel-like material that has been piled up and deposited there from a massive flood, like a really big set of gravel bars. From the DTM of Soderblom et al. the elevation of the spooky dude formation is quite high, indicating a really, really massive initial flood would be required to form a deposit. (The shape of the parabolas indicates the emplacing flood would need to be from NW to SE)

I’m really hoping the T41 RADAR swath can help give another set of data to help sort out these terrains.

-Mike

Thanks Mike for the useful comments on the full article, which I am unable to see without forking out the ridiculous sum of $30.

There still seem to be more questions than answers, though, particularly regarding timescales for the various processes. Icy highlands completely mantled in bright 'reddish' stuff and adjacent floodplain (including the pebbles) not so mantled at all. Mmm. An active process removes all the mantling here on a timescale of decades?? To where? Not onto the floodplain apparently.

If this active process cleans off even the tops of the high pebble banks why does it not also clean much of the highland terrain? How thick is the highland mantling anyhow? Are these highlands actually icy at all? Could they instead be the remnants of thick organic deposits formed when this place was at a higher latitude? But in that case where do the presumed icy bank-forming pebbles originate? From cryovolcanoes?

The questions are muliplying like rabbits. It may take more than another SAR image to bring the population under control.

Please be patient, I'll try to make this paper available for free somewhere. But we have to make sure we don't violate copyright restrictions.

That would be much appreciated. We are extremely grateful here to authors who make material available free, whenever that can be done. There is obviously going to be public interest in this material. It's the policy of the journals and the obsolescent copyright regime itself that I was having a go at. We're all saddled with that for now, but it has to collapse eventually, so let's keep pushing.

Thank you in advance! That would be immensely appreciated!!!!

Would it be possible to have any of the images or graphics posted? (Crude drafts, slide images, anything that isn't copyrighted.) The images of spectral ratios combined with the DISR images spoke volumes.

-Mike

The Keller et al. paper "The properties of Titan's surface at the Huygens landing site from DISR observations" (Planetary & Space Science, in press) can be found here (5.1MB).

Interesting fact: we are using an image (with permission) previously posted by tfisher! IMHO a credit to the quality of this forum!

While I'm plugging our papers, I might as well add a link (1.1MB) to the Schröder & Keller paper "The reflectance spectrum of Titan's surface at the Huygens landing site determined by the Descent Imager/Spectral Radiometer" (Planetary & Space Science, in press).


You can simply use the Snapshot tool in Acrobat Reader to copy any image you like!

Fantastic! Thanks a million. Those papers are almost a whole book in themselves. I particularly like the image of Titan's sky as seen from the surface.

Thank you very much!!!! I'm going to enjoy digging into the depth (pun?) of the spectral data.

-Mike

From Keller et. al. page 28 -

Bright patches in the lake area are deposits of land material transported into the lake bed by the rivers.

But from page 7 -

Consider the river area north of the landing site. . . . Just before landing, when observed at higher phase angles (typically 65 degrees) this had darkened relative to the lake bed, most notably along the coast line and the rivers. This darkening appears to be restricted to the river area and is not seen for the bright islands in front of the coast, whose nature seems to be fundamentally different (- my underlining.)

And -

The fact that the strongest darkening is associated with the coast line and the rivers themselves, suggests that steep slopes (scarps, overhangs) also play a role

Plus one personal observation: Near where I live there are a number of coastal locations where soft cliffs of boulder clay are fronted by shingle beaches. The pebble beach looks very different from the clay cliffs from which the pebbles fall. The surface of the cliff is pockmarked with indentations where pebbles have dropped out and these indentations often contain shadows.

I think it's fair to say that we still can't be sure of the true relationship between the East Adiri highland terrain and the pebble banks, least of all whether both, or one, or neither is made of water ice.

From page 4 of the Schröder & Keller paper


Is this the direction Huygens was facing after landing?

Yes. East is zero degrees, azimuth running counter-clockwise.


I think we can (and do) not claim that all the bright islands in the lake bed are deposits of eroded land material, but some probably are. I fully agree with your conclusion that we do not know the true relationship between the highland terrain and, what you call, the pebble banks. Are these truly pebble banks? The analogy you provide is certainly very interesting...

It was facing south then?

I strongly feel that if we can figure out the story of the "Spooky dude formation" what it's made of, how it got there, and what carved it's shape, it will give us a great idea of the geological and fluvial processes that occurred in the basins on Titan's surface.

(The dunes would tell the complementary eolian story).

The Spooky dude formation is the closest feature to the Huygens landing site. The Huygens probe might have actually landed on the ice-sand (mud?) covered edge of the formation. Careful spectral analysis might be able to dissect the components of the Spooky dude formation in relation to the bright highland terrain. (Which may be also different than the near shore "Long Island" feature.)

-Mike

I agree, Mike. A more fortunate low-latitude location for which to have ground truth could hardly be imagined. It could so easily have been a more 'typical' spot with only one type of surface within visible range.

I think the Huygens mission planners scored a billion mile 'hole-in-one'. The Huygens Landing Site itself would be interesting target for a follow up mission.

(Bonus, you'd get a direct measurement of surface accumulation rate by looking at the exposed metal surfaces of the Huygens probe).

-Mike

Better take a metal detector. You might find it buried in a new pile of rubble half a kilometer away!

Indeed.

Audio/transcript is now posted for the latest CHARM on Huygens DISR data. (Hoping I'll now be able to make some sense of all those graphs!)
http://saturn.jpl.nasa.gov/multimedia/prod...ARM_Tomasko.pdf
http://saturn.jpl.nasa.gov/multimedia/prod...ARM_Tomasko.doc
http://saturn.jpl.nasa.gov/multimedia/prod...ARM_Tomasko.wav

Using the relative spectral fingerprint ratios of the different terrain units (Equatorial Sand Seas thread, post 319) it might be possible to assign terrain units to some of the features observed at the Huygens Landing Site.

Indicated below are four features in the Huygen’s Landing Site DISR image mosaic that I’ll refer to as Huygens Island, Spooky Dude formation, mid-channel muds, and South Island. (all names unofficial ).

Click to view attachment

During its descent, the Huygens probe collected a spectral mosaic at 18 km and 4 km altitude at various wavelengths. The recent publication by Keller et al. Planetary and Space Science (2008) "The properties of Titan's surface at the Huygens landing site from DISR observations"
doi: 10.1016/j.pss.2007.11.020 provides false color maps based on corrected spectral ratio footprints overlaid on the DISR visual image mosaic. (Selected images reproduced here are with permission from the author). These can be used to try to assign terrain types. Caveat: as mentioned in the article, “the position and orientation of the individual spectra and the maps as a whole are not 100% accurate.”

Click to view attachmentClick to view attachment

In the graphics above are the spectral maps at 18 km and 4 km altitude of the Huygens Landing site for the 1.59/1.28 um ratio. Note that the points selected on the 18 km and 4 km images for feature spectral identification are not the same. I tried, however, to select the best square that overlapped with the desired feature. These selected squares are consistent throughout the spectral ratios for a given distance.

In the 1.59/1.28 um ratio, Huygens Island has the highest spectral ratio, followed by the South Island, then the Spooky Dude formation and the mid-channel muds are about the same. In the 4 km altitude image, the mid-channel muds spectral ratio is still pretty similar to that of the Spooky Dude formation.

-Mike

Click to view attachmentClick to view attachment

In the graphic above is a set of spectral ratio maps of the Huygens Landing Site at the 1.28/1.07 ratio overlaid on the DISR mosaic at both 18 km and 4 km. Huygens Island still has the highest ratio, followed by South Island, with the Spooky Dude formation and the mid-channel ice muds at nearly the same low ratio at the 18 km view. At 4 km the same relative ranking occurs: the Spooky Dude formation is at the low end of the ratio "spectrum" and the the mid channel ice muds are the darkest (lowest ratio).

Click to view attachmentClick to view attachment

Above are the spectral maps at 18 km and 4 km for the 1.07/0.93 spectral ratio. Again, the Huygens Island is the brightest, followed by the South Island, then the Spooky Dude and the mid-channel ice sands at the lowest ratio end.

These relative spectral ratios for the four features can be combined to create a spectral fingerprint for each feature. This can then be compared to the spectral ratio fingerprints of the previously identified terrain types.

-Mike

From Soderblom et al., Planetary Space Science 2007, the Huygens Island was determined to be the Equatorial Bright unit and the mid-channel muds were determined to be dark blue ice unit. With these assignments, it is possible to now fit the relative ranking of the fingerprint ratios from the Huygens DISR images into the previously defined spectral fingerprint ratios of the terrain units. This is shown on the slide graphic below:

Click to view attachment

From this analysis, it appears that the South Island could be Equatorial Bright terrain that has been mixed with a darker unit (most likely deep black, least likely dark blue ice sands due to the relatively higher 1.59/1.28 ratio than would be expected of a mixture of these two components.) This would be consistent with an Atoll-like Rotten Terrain with deep black or dune sands.

The Spooky Dude formation is least consistent with Equatorial Bright terrain. It is most consistent with Dark Blue unit. However, DISR visual images show that this terrain is relatively bright. It is consistent with dark blue unit in the infrared, but is much brighter in the visible. It is as if the visually dark blue ice sands (or cobbles) unit were washed free of a shorter wavelength absorbing component. The Spooky Dude unit is thus consistent with "washed" (= visible range brighter) water ice cobbles or sands.

-Mike

Interesting, however the most recent DISR results paper suggests that the apparent difference between the two DISR 'islands' may be attributed mainly to angle of illumination. Are you saying the spectra contradict this?

Not directly, no. The spectra support both possibilities.

The angle of illumination will affect the amount of light reflected. (Reflected light has absorption, specular, and diffuse reflected components - only the absorption is illumination angle independent).

[Other effects to worry about are forward scattering of hazes, and backscattering of hazes - these will be incidence angle, distance (different distances to different features from the lander) and wavelength-dependent, and all this compounded by albedo effects. Using wavelength ratios helps with the incidence angle effect, and the distance effect for a particular spot on the ground. But even the wavelength ratio will not remove albedo effects.]

It's important to point out that Rotten Terrain and Equatorial Bright terrain appear to be spectral cousins. (My hypothesis is that Rotten Terrain = Equatorial Bright terrain + varying amounts of darker stuff in the pits)

My waaay oversimplified analysis is putting everything on an absorptive difference between the two terrains that causes a decrease in spectral ratios for the South Island.
Additional support for my speculative claim that the South Island terrain is Rotten Terrain-like comes from DISR visual mosaics that show dark spots and pits in the terrain, as well as the T8 RADAR swath which seem to show that both islands have subtle differences.

IIRC , the analysis by Keller et al. (2008) placed most of the emphasis on the differences due to illumination angle that cause the difference in spectral ratios measured by Huygens.


How could additional observation by Cassini help determine the identity of South Island terrain?

A high resolution VIMS image of the Huygens landing site region would provide additional evidence.
Especially the ratio between 2.7/2.8 - with closer wavelength differences the wavelength-dependent factors will be minimized. In addition, the deep black material, (which I suspect is filling in the dark spot) has the lowest value (is darkest) at this wavelength ratio. So I would expect the two islands to appear most different at this ratio if they are different terrain types.

Additional evidence might already be seen in the T41 RADAR Swath. Higher resolution RADAR imaging might provide further evidence of pits and the aspect of Rotten Terrain on the South Island.

(Topo SAR might help. If one island is paved flat (i.e. South Island) and the other is higher (i.e. Huygens Island), then at least one could say there is a morphological difference between the two islands. Whether or not this is due to structural differences would be open to debate.)

I'm not sure if regions of Rotten Terrain have any properties that clearly set them apart using other detection modes, like scatterometry, radiometry or dielectric constant determination.


-Mike

Thanks, Mike, for that full reply. Yes Keller was the one. After reading that paper I found myself imagining (not for the first time) the 'island' material resembling a honeycomb full of voids. Such a surface could appear MUCH darker when viewed into the sun due to shadowing in the voids. It's interesting that only the Huygens panorma suffers from this extra complication due to the big range of phase angles within a single mosaic. Impossible I'd say for Cassini to check this out since any one view will obviously all have the same phase angle, and even the range of phase angles available for multiple views is limited when viewing through the atmosphere. The observations you propose, though, are exactly the sort that would be most helpful here and I'd be surprised if they're not already in the planning pipeline.

Lightening on Titan? Does anyone know enough to speak on this, i've no idea what to make of it!

Not sure.

To make the really neat-o (!) molecules that will get biologists excited, you need to get oxygen atoms in the molecules. The problem is that most of the oxygen on Titan is locked away in frozen, insoluble water ice.

So you've either got to get hydrolysis to occur following an impact event (and subsequent melting of water ice), from organics getting cycled down deep into the subsurface ocean or in contact with molten cryo-lava, or during a lightning strike blasting into the surface ice.

If the lightning on Titan is cloud-to-cloud, it can help activate the CHN chemistry (although I don't see how it will differ from UV photolytic chemistry).

But if the lightning on Titan is cloud-to-ground, then you can imagine getting chemistry at the surface to start incorporating H2O into the product molecules. And there's been some recent experiments that studied that striking scenario.

So the level of excitement it depends on what the lightning hits.
[/pun generation]

-Mike

This refers to electric events at the lower atmosphere, apparently:

http://dx.doi.org/10.1016/S0032-0633(03)00119-3

http://dx.doi.org/10.1016/S0273-1177(97)00361-X

Talking about spooky images, imagine St. Elmo fires over the titanian lakes.

Just looked this over. To a first order, nothing newsworthy here. The paper has a detailed discussion
of electromagnetic wave propagation and the formation of Schumann resonance, and a lot also on
digital signal processing. It sort-of concludes that the Huygens data show a Schumann resonance and
that that definitely implies electrical activity (WHICH DOES NOT NECESSARILY MEAN LIGHTNING) on Titan.

The Schumann resonance detection had been reported - rather more tentatively - before, by the HASI team
that built and understood the instrument. This new work is not by the instrument team (I heard some months
ago from one of the HASI team that someone was working on the data from the PDS but had misunderstood
some calibration issues - I don't know the veracity of that remark, nor whether this new paper is that
investigation)

One interesting wrinkle is that this paper points out that the vertical electrical field signature is much stronger
than the horizontal field (which HASI nominally measures). But the probe tilted significantly during the early
part of descent (this new work cites my paper in support) allowing the horizontal HASI sensors to project
vertically and allow more of the Schumann signature in.
[Although there is not at present any analysis that shows the HASI data acquisition at the same
second or fraction of second when the tilt is significant: in fact I have my own theories about whether the
HASI booms were fully deployed during the early part of descent - some aspects of the spin and tilt behaviour
may suggest one was not]

So, my take.

1) good that new people are looking at the data. Schumann resonance is something people had only
really discussed about Earth before Huygens (although there was one paper by Sentman about an ionized
layer in Jupiter's interior forming a resonant cavity) - it's something that definitely merits further study on a
future mission (from a platform not plummeting through the sky, and desirably for weeks/months rather
than hours, and apparently looking at the vertical field rather than horizontal..)

2) you have to be really careful with probe data without understanding the probe. Not like a camera on Cassini
where it is the same instrument taking hundreds of thousands of pictures under well-understood conditions over
years. Probe was a one-off for just a couple of hours, in a very dynamic environment, not well-understood - and this
sort of measurement isnt even made on Earth from balloons that often.

3) decent paper, albeit slightly incremental. Possibly requires caution about instrument interpretation. Indicates
electrical activity (which may or not mean intrinsic to the Titan environment - could always be triboelectric
issues with the parachute - and if so may or may not mean lightning..) and attributes it to Schumann resonance
(which may or may not require a lower conductive boundary, aka internal water ocean)

Thank you VERY much for that cogent analysis, Ralph; really put the whole thing in perspective!

Ditto - much appreciated. I was wondering if the inferred electrical activity has to be within the atmosphere, or could it equally well be a subsurface phenomenon: piezoelectricity or something else maybe related to tidal stresses, cryovolcanism or whatever (waves arms furiously)?? I have a vague recollection that Huygens detected some kind of transient event several minutes after landing and that this didn't get any satisfactory explanation at the time. Probably a complete red herring I know.

New article in press at Icarus (available online Nov 17, 2008):

Karkoschka, E.; Tomasko M.G. Icarus (2008?) article in press. "Rain and Dewdrops on Titan base on in situ Imaging." doi:10.1016/j.icarus.2008.09.020

Data from Huygens probe descent was analyzed.
Two darker haze layers at 11 and 21 km thought to be due to 10% larger aerosol particles
These drops not enough to be considered rain (or drizzle).
If typical, the Equatorial Zone is inferred to get <0.1 mm/yr rain.

(That's pretty dry. It is 100 x drier than the Atacama desert - the driest place on Earth.)

The authors contend that "interpreted splashes" in the Huygens surface images are not real, with the exception of a drop of methane condensate that fell off a baffle.

-Mike

Interestingly, it is also about 10x less than the time-averaged precipitation rate estimated from convection energy Ralph Lorenz in 2000 (6 mm yr-1 based on 0.5 mW m-2.

So if the convection energy estimates are correct, and if the Equatorial zones has 10x less precipitation than energy dictates, somewhere else (poles - mid-latitudes) need to make up for this more precipitation to balance everything out.

-Mike

Sounds eminently reasonable to me (Note that the Tokano 2006 'drizzle' - an inference rather than a
detection - violated that energy constraint).

That said, one shouldnt read too much into a single point measurement - the long-term average that is bounded
by the energy limit is (light drizzle all the time as constrained here) + (occasional downpour that statistically we
are unlikely to see with only hours/days/years of observation). At any or maybe all latitudes, it might be that the
second term dominates.

FWIW metadata on this new paper - I've worked with Erich on HST stuff a while back - he's a very careful guy,
really understands the DISR instrument. I think you can trust these new findings.

Is it possible that more than one picture have been taken on the surface and therefore, a slight change has been noticed ?

http://blog.wired.com/wiredscience/2008/12/titanmethane.html

Raoul - see http://www.unmannedspaceflight.com/index.p...ic=5688&hl=

Here's an animated GIF showing different coordinated views of the Huygens Landing Site:

Click to view attachment
(click to animate)

sequence loop:
1) DISR PIA06438 + T8 SAR RADAR
2) T8 SAR RADAR
3) ISS
4) T41 SAR RADAR
5) T8 SAR RADAR
6) T8 SAR RADAR + DISR PIA06437
7) T8 SAR RADAR + DISR PIA06437 + PIA06438
8) T8 SAR RADAR + PIA06438
9) T8 SAR RADAR
<repeats>

The T8 and T41 SAR RADAR are at full resolution (256 pixels/degree). PIA06437 is about the same as pulled from the web, but PIA06438 has been shrunk to only 10% or so it's original size from the Planetary Photojournal.

-Mike

That's really nice Mike, although the registration doesn't seem quite perfect yet. I notice one feature in particular that jumps around a bit and that's the square 'enclosure' with very dark interior and bright walls located at about 8 o'clock from the landing site in the DISR mosaics. This is one feature that does seem to have a RADAR trace (and there may be another similar to the south of it). This feature is especially interesting because if I'm not mistaken its one for which we have a DISR 3D rendering. As I recall it is surprisingly tall - a mini plateau with a dark basin inside which is still higher than the surrounding plain, with a suggestion of an exit channel at one corner.
EDIT
Here it is (I think):
http://photojournal.jpl.nasa.gov/jpegMod/PIA06442_modest.jpg

Actually, the feature shown in PIA06442 is part of the Spooky Dude formation and is located almost directly to the W of the Huygens Landing site.

But you are right, there is a slight jump in the coordination.

-Mike