Here is an attempt to match the approximate location for the Huygens probe touchdown based on the PIA08114 mosaic and the surface image.
I’ll assume that the mosaic center is close to the Huygens landing site.
Here is the article that pinpoints the location of the probe landing site:
Karkoschka et al., Planetary and Space Science 55 (2007) 1896-1935. “DISR imaging and the geometry of the descent of the Huygens probe within Titan’s atmosphere.” doi: 10.1016/j.pss.2007.04.019.

A key section of the article is Section 8.5 – Terrain near the landing site
From the article: “The images after landing looked at a central azimuth of 193 degrees.”

Another portion from Section 8.5 from the article:
“In the SLI images of the landing site, the apparently flat area with rocks may extend to about 30 m distance, where the rocky area turns into an area without small features. This transition may be the transition from flat terrain to the relatively steep slope climbing almost 1 m across 1-2 m distance. If the furthest rocks visible are at a distance of 30 m, they are just about the same size as the rocks seen in the foreground. In the left part of the images taken from the surface, there is a bright, horizontal line between the end of the rocky area and the horizon. This could be the closer hill, while the horizon marks the further hill, some 5 m further away. These are our best guesses, while other guesses are equally valid.”

Another key sentence: “Note that the largest rocks of some 20 cm diameter seen on the ground are smaller than the pixel size of 30 cm in frame 716, or the PSF size of 50 cm.” Thus the cobbled littered portions would appear smooth to the DISR images.

So using the literature article and matching PIA08114 with PIA08115. (To give full credit, I think the authors of the Karkoschka et al. article were also responsible for the assembly of both PIA08114 and PIA08115):
Click to view attachment

For reference, the large paramecium-shaped feature at the center of the DISR image is about the size of a house.
-Mike

Mike, there is a feature on the horizon at the right (reading the horizon from L to R it's at about 80-85%) that looks to me like a hill with a bright face. It's almost the same tone as the sky but seems to be just distinguishable. I wonder if that can be identified with any of the individual bright patches in the vertical view?

Here is an enhanced-contrast B&W crop of PIA08115 in 5x Tall-o-Vision:
Click to view attachment

If PIA08115 is the equivalent of the left part of Figure 13 in the text, it is "the average of all SLI and MRI images taken after landing".

The distant bumps seem to be descending from left to right (facing SSW, thus E to W).

The bright patch, could be a bright patch on the rocks, a more glancing (specular like) reflection off a surface, distant line of a rock-rise beyond the near set of hills, or a mirage-like phenomenon, or an artifact.

Without knowing the exact scales of the bumps on the ground, and without knowing what is in the poorly resolved area of the "paramecium-like structure", it is hard to determine which of bumps on the ground line up.

But if I had to speculate, I'd move the proposed site above over a few meters to the E. So that the three brighter points on the southernmost end of the
paramecium, are the three largest bumps in the image.

-Mike

Here is an alternate placement for the Huygens probe based on a Tall-o-Vision horizon match with the DISR mosaic (I rotated the DISR image so that S is at top) (Annotated features lined up with colored arrows):
Click to view attachment

It places the landing spot a few 10's of meters to the E. The darker bumps on the horizon line up with the brighter nodes in the DISR mosaic.

But the distance between the two bright lines (estimated in the text at 5 m) appears too large with this lineup.

(Of the two, I kinda prefer the first placement with the horizon line being part of the poorly resolved area in the "paramecium" feature)

-Mike

I like that Mike - but you've turned my 'bright hill' into a dip! Also, are you sure the horizon gradient isn't due to the slight tilt of the lander?

Paramecium!! Whatever next? Potato-shaped, or even slipper-shaped, I could understand . .

Closer and closer....details of the channel muds.
Pseudocolorized version of a flattened crop from the DISR mosaic PIA08114:
Click to view attachment

Image dimensions are approximately 1.9 km x 1.9 km. (ca. 1.5 m/pixel).
A larger JPEG version can be downloaded here: http://www.flickr.com/photos/31678681@N07/3262212964/

The Huygens probe landed just outside the (buried?) margin of one of the enigmatic hollows of the "Spooky Dude" formation.


Here is an even closer image. The brightish feature at center is likely just to the south of the Huygens Probe touchdown point:
Click to view attachment

Image dimensions are approximately 1.2 km x 1.4 km (at 80 cm/pixel).
An 80 cm/pixel version can be downloaded here (as a JPEG): http://www.flickr.com/photos/31678681@N07/3262214012/

-Mike

Pseudocolorized version of a flattened crop from the DISR mosaic PIA08114:
Click to view attachment

Image dimensions are approximately 600 m x 500 m. (ca. 38 cm/pixel).
A larger JPEG version can be downloaded here: http://www.flickr.com/photos/31678681@N07/...60359/?edited=1

The "castle"/"paramecium"/"potato shaped" thing at center is roughly the size of a house.


Here is the final crop. It is a 2-fold enlargement of the center section of PIA08114. This guess localizes the HSL within 10's of meters on Titan's surface. The Huygens Probe touchdown point is about halfway to the top of the image from the center. The ridgeline of the "castle" is the object seen as the horizon from the surface image:
Click to view attachment

Image dimensions are approximately 300 m x 200 m (at 19 cm/pixel).
An 19 cm/pixel version can be downloaded here (as a JPEG): http://www.flickr.com/photos/31678681@N07/...stream?edited=1

-Mike

Trying to put a more human scale on the Huygens Landing site, I poked around Google Earth for a similar sized and shaped island to Huygens Island, along with a similar-sized channel and with sufficient high resolution imagery to zoom in for comparison at closer scales:

Click to view attachment

The result: Lesbos Island, Greece.
(BTW, be kinda careful when searching "Lesbos" on the internet...)

One giggle is that Lesbos Island and many of the areas around it are of Aeolian origin.

-Mike

Zooming out from HSL compared with zooming out from Lesbos Island, Greece
(For Titan, the top of the page is N; for the Earth comparison views, the top of the page corresponds to SSW)

Huygens Island and E Adiri compared with Lesbos Island, Greece and the Biga Peninsula, Turkey:
Click to view attachment

E Adiri and Anitilia Facula, Titan compared to NW Anatolia and the Aegean sea on Earth:
Click to view attachment

Finally, Adiri, Ching-Tu basin, W Shangri-La basin and E Belet basin vs. Anatolia and the Eastern Mediterranean and Black seas (Italy at far right):
Click to view attachment

(Note the similarity of the chain of bright islands in Ching-Tu basin and chain of islands (including Crete) in the Greek archipelago)

-Mike

Zooming in and comparing the HSL with the ancient city of Assos (across the strait from Lesbos Island):
Click to view attachment
(Right image is centered on the middle of the strait between the Biga Peninsula, Turkey, and Lesbos Island, Greece)

Zooming into the Biga Pensinsula side of the straight and the ancient village of Assos (Wikipedia: Assos). Assos is at the crossroads at lower center. The port has a small marina.
Assos was founded in 1000 BC by Aeolian colonists from Lesbos. Aristotle had an academy here.
Click to view attachment

Closer in, the marina structure is about the same size and shape as the "castle" in the Huygens DISR images:
Click to view attachment

Even closer, fishing boats can clearly be identified in the Marina of Assos. On the road at lower left, cars can be seen. The Huygens probe was about 1 m across, and thus would not be easily identifiable at even this close scale:
Click to view attachment

-Mike

Excellent idea - after looking at your comparisons I have a much better sense of scale!

The more I manipulate landing site images the more tantalizing they are at the limit of useful resolution. As for possible landing places - your 1 and 2 both look equally feasible to me. Both seem to be in/near dark 'smooth' sort of looking areas that might equate to the ground pic broad shallow drainage channel.

Updated "Cosmic Zoom - Titan style" here: http://www.flickr.com/photos/31678681@N07/3264954029/
(links to a flickr page, click on arrow to begin playing)

[It looks pretty cool in full screen mode]

-Mike

In the T41+T8 SAR RADAR Swath combination, RADAR-dark blobs or pockets can be seen that have a lobate morphology.
These are indicated by yellow arrows in the graphic below (Huygens Landing site approximated by a red cross):
Click to view attachment

Some of these are very close to the Huygens Landing site.
Similar features were seen just to the northeast near the Flower Petal Crater (see post 375, Equatorial Sand Seas thread; and post 377, Equatorial Sand Seas thread)

Here's a graphic that lights up the RADAR-dark/ISS-bright terrain near the Huygens Landing site:
Click to view attachment

To make the image, the T41+T8 combined RADAR image was inverted, contrast-stretched, then the inverted image pseudocolorized (dark-->light in invert image = red-->white).
The ISS-DISR image was contrast-stretched and pseudocolorized (dark-->light = blue--->white).
Then both images were added (Photoshop "Apply image) with an offset of about -175.

In the resulting image (RADAR-dark and ISS bright) features are lit up as bright white.

The black arrows show the correspondence between the features in the images.

Comparing the Combination image of the pseudocolorized[inverted (T8/T41 RADAR)] and pseudocolorized[ISS-DISR] with the VIMS recently acquired by Cassini. VIMS data reproduced from Jaumann et al. LPSC 40 (2009) Abstract 1599. "Erosion and Stratigraphic relations on Titan."

VIMS image reproduced from Jaumann et al. LPSC 40 (2009) Abstract 1599. "Erosion and Stratigraphic relations on Titan." http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1599.pdf
Click to view attachment

The brightest spots ("brightest of the bright" terrain) match up between the two images. These are indicated by black arrows.
Note how the brightest VIMS "bright terrain" spots actually correlate to RADAR-dark lobate flow material!

For these terrains, the VIMS is negatively correlating to RADAR SAR brightness!
It is smooth bright material (smooth IR-bright flow material???)

Here are DISR images of the RADAR-dark/ISS-bright terrain closest to the Huygens Landing site.
(The Huygens probe landed pretty close to this feature - about 8 km away)
Click to view attachment

-Mike

Here's the a better image of the Pseudocolor Matrix image of the Huygens Channel.
{Pseudocolorized (red-->white)[invert(T8+T41 SAR RADAR)]}+{Pseudocolorized (blue-->white)[ISS+DISR]}
Click to view attachment

A full resolution TIFF (256 m/pixel resolution) is available here: http://www.flickr.com/photos/31678681@N07/3357028020/

-Mike

Here is a predicted VIMS model of the Huygens Channel region on Titan:
Click to view attachment

To make this model, I let the pseudocolor gradient be driven mostly by the ISS[0.93 um] spectral response and it's correlation with VIMS terrain type. Then I applied a gentle pseudocolor gradient using the inverted [T8+T41] SAR RADAR of the same region. This allows the RADAR dark/ISS-bright regions to become brighter, and the strongly RADAR bright mountain regions to become slightly VIMS darker.

Here is a blink animation that compares this to the VIMS data presented in Jaumann et al. LPSC 40 (2009) Abstract 1599.:
Click to view attachment
(click to animate)

-Mike

Huygens conference:
http://www.saturndaily.com/reports/Huygens...anding_999.html

Pardon my ignorance, but can we expect anything new from this conference? I'm was under the impression that we've about squeezed all we can out of Huygens data.

Well, here's a phrase copied from the link above:
results from studies of this moon using remote sensing from instruments on the Cassini Orbiter combined with Huygens data

In particular the VIMS closeup of the landing site could come into play here. (That's what I'm hoping, anyhow - knowing nothing but ever optimistic. )

Cassini's obtained a LOT more contextual data since the landing, so this conference sounds like an attempt to get all the major workers together to generate an integrated interpretation of the results. Additionally, it looks like there will be some post-facto engineering review activity, which is always important for planning the next generation of probes.

Following the links a bit further:
http://www.titanexploration.net/scientific-programme.php

(And yes there is a presentation on VIMS/DISR comparison. )

Also, remember that although the Cassini team meets regularly, the Huygens team isn't necessarily part of those meetings (unless of course you're talking of individual scientists who had roles on both missions). This would be an opportunity for Cassini people to present the latest stuff to Huygens people and for them to discuss how recent Cassini results fit into the context of the Huygens work.

A lot of neat presentations listed Good time to review.


Craig

When can we expect to know the information presented at this meeting?

A good question. There seem to be no abstracts posted, but there may be news releases over the next few days. Even better, perhaps we have members attending who will be willing to share highlights of the event.

Why are a few of the threads marked "Pinned" and what does it mean or imply?????

Re - pinned threads. I'm guessing they're 'sticky' threads Floyd - i.e. important topics/discussions that always appear at the top of the forum, regardless of the last modification date.

5 years ago today Huygens landed on Titan!

A brief general summary of past knowledge and images posted on the ESA webpage:
http://www.esa.int/esaCP/SEMDU4MJ74G_index_0.html

Five years... cripes... If I remember correctly, I was giving an Outreach talk in a junior school at the time of the landing, a "Tour of the Solar System", and when it came to Saturn I showed the classic old Voyager pic and told the class "By the time you go home we'll have pictures of this world's surface"... After the talk I rushed back to my mother's house, just a stone's throw from the school (as the little *******s proved more than once!), to go online and see the pics. That really was something, seeing the surface of a world I'd seen countless hundreds, maybe even thousands of times, through my small telescope. Those Huygens images turned a point of light into a real world for me. Next time that will happen will be when NH reaches Pluto...

Yep, half a decade my friend...
I also remember that special day...I went rushing home to see the images but knowing that I wouldn't see them as they reach the internet I saw this deserted public internet outpost and there I stand, seing a whole new world unveiling before our eyes. What a night!

Dawn not good enough for you?

I remember the Huygens landing well, woke up early (didn't really get much sleep at all) and skipped college lectures that day just to watch the live ESA event (and via a NASA TV webcast at that!). The most emotional moment for me was when the Green Bank Telescope acquisition of Huygens carrier was announced and there were Huygens people literally crying with joy. That was it, the probe survived reentry and was working! It could only get better from then on. Actually seeing the first surface image in the evening that day, I had a hard time bringing myself to actually believing it. I frequently wish there was a recording of the live event somewhere, I'd like to live through it all again.

The DISR movie on the ESA site really is a thing of beauty (tones too).

Good point!

At long last, the un-annotated version of the Huygens landing site VIMS image appears in the latest CHARM presentation.

From the CHARM slides its sounds as if a 3D-accurate mapping of Radar, VIMS and DISR (Karkoschka) is in the making!
In the meantime I've made a mapping with the CHARM VIMS image and Mikes T41 and T8 composite and the Vortex processed DISR (Karkoschka) image. Although not very bright in the final image I believe the 'enclosure' and the 'dude' arrowhead is visible and distinct in the Huygens channel.
Click to view attachment

Aah - thanks for doing that. I'd been doing it as well as I could in my head and come to the same conclusions. Now the question is what detailed spectral differences can VIMS pick out between 'dude' and 'interdude'? Also, can any 'cats eye' RADAR bright spots be identified or not? Then we just might be homing in on the likely composition of the pebbles. That paper when it comes out could be one of the most significant on Titan so far.

I don't normally look at twitter stuff but these few from Emily might spark some discussion:

# Griffith: These are tiny, isolated regions with markedly different properties. Barnes still thinks she's wrong. #DPS2010 (about 1 hour ago)
# Barnes comment on Griffith paper: "This is good work, but to be honest I think it's wrong." #DPS2010 (about 3 hours ago)
# Griffith: Evidence in VIMS near Huygens site for liquids of depth less than 1 meter -- tropical puddles among dunes on Titan #DPS2010 (about 3 hours ago)

Huygens found quite a high level of methane humidity at the landing site, so both views seem plausible to me. Comments??

The first paragraph on page 186 here describes this.

I've been reading up on drying clays (for fun), and also protein crystal structures (for work), and strangely enough there is a very common theme.

From what I understand, there are four types of bound solvent (water in the cases above):
Loose solvent: contained in macropores or interstitial spaces.
Tight solvent: the layers of solvent molecules immediately next to the surface (two molecular layers deep)
Bound solvent: solvent molecules actually localized and "pinned down" in a crystal lattice. These can be detected and localized in an X-ray structure. (Loose solvent molecules move around too much to localize by X-ray.) I'd classify clathrated methane as a "bound solvent".
Ligated solvent: these molecules (or portions of molecules - like a hydroxy for water) are actually coordinatively bound to an atomic center (usually a metal for a hydroxy) in the inner coordination sphere. There is electron density between the two coordinating atoms (oxygen giving it's lone pair to the metal center).

[For Titan's liquids: ligated solvent probably won't happen, with the possible exception of solvent nitrogen possibly coordinating it's lone pair or pi-orbital density to a massively elecrophilic center - maybe like a carbenium or carbonium ion. In the laboratory, reactive metals (CpCo(I)L2 f'r instance) are postulated to do this - I don't remember if it is side-bound (eta-1) or end-bound (eta-2) or both)]

The loose solvent evaporates quickly, but the tight solvent evaporates slower, and the bound solvent basically stays put. Once Huygens landed, the warm probe may have displaced some of the tight solvent and the bound solvent from the crystal lattice.

[Fun experiment at home, make Epsom salt crystals (MgSO4) by cooling a hot aqueous saturated solution of Epsom salt in a jar. Then take the pretty clear crystals (which have several waters of hydration in the lattice) and put them in the oven at low heat. They will come out all cloudy as the water of hydration is driven off. In the chemistry lab, I use MgSO4 (anhydrous) as a drying agent to suck water out of organic solution - when water gets reincorporated it releases noticable heat.]

Article coming out in Icarus describes further analysis of Huygens probe penetrometer data (see Ralph's avatar for image of instrument).

Atkinson et al., Icarus (2010) Article in press. "Penetrometry of granular and moist planetary surface materials: Aplication to the Huygens landing site on Titan". (doi: 10.1016/j.icarus.2010.07.019
Abstract here (will be coming out in December of this year)

The authors examined the three stages of data.

1) The subtle ramp up to 2 ms, which they hypothesize is due to a thin (ca. 7 mm) coating of material weaker than terrestrial snow. (very fluffy stuff)
2) A sharp spike at 2 ms, which was reproduced in their experiments by "impacts with small pebbles or with hard crusts". For the pebbles, they felt that a 16 mm spherical particle was a match.
[I don't know if the hard crust possibility was investigated further.]
3) From 2.5 ms to 11 ms, there is a decreasing force tail, implying a decreasing resistance. This was a closest match with wet sand, with dryer sand up near the surface, and wetter sand below. However, the authors point out that even terrestrial wet sand isn't a perfect match. It seems as if Titans soil become even less resistant with depth compared to the wet sand analog.

Here is a graphic that sums up the results showing a hypothetical cross-section at the Huygen's landing site:
Click to view attachment

New animation of the Huygens landing and analysis of the ground where it landed was released today at http://www.esa.int/esaSC/SEMJP13S18H_index_0.html

"Since the dust was easily lifted, it was most likely dry, suggesting that there had not been any ‘rain’ of liquid ethane or methane for some time prior to the landing."

This seems to be in contradiction with earlier results showing the presence of liquid methane in the soil, close to the surface.

The article also quotes: "...the probe likely encountered a pebble protruding by around 2 cm from the surface of Titan, and may have even pushed it into the ground, suggesting that the surface had a consistency of soft, damp sand..."

Rather than a contradiction, I see this more as a refinement between wet sand and damp sand models. Even the first description after the landing - creme brulee - suggested a dryer surface over a wetter interior.

The statement: "...suggesting that there had not been any ‘rain’ of liquid ethane or methane for some time prior to the landing" is vague. Days? Months?

A refinement, not a contradiction (I am a co-author of the DISR work just published, led by Stefan Schroeder and Erich Karkoschka). Titan is (consistently) interesting enough to defy the simplest descriptions.

It rains sometimes, not often. The subsurface was damp, the top few mm were not. Go to a beach a couple of days after rain and you'll see the same sort of thing (except the evaporation timescale may be very different for Titan).

The dust kicked up and indicated in the DISR optical instruments for a couple of seconds seems consistent with the thin fluffy layer indicated by the penetrometer.

The error bars are still quite large, and will remain so until we've surveyed Titan for a half-Titan-year (we're at about 1/4 so far, with gaps), but there are estimates of total volume of precipitation, and precipitation per storm, plus the constraints we have on the frequency of such storms (we've seen one very large one). When I was reading the literature, looking for a consistent model that fit those various constraints, it seemed to fit if the equatorial regions experience rare, but very large storms, which deposit hurricane-like quantities of rain. A given location in the equatorial regions might go a very long time between storms, on the order of perhaps 80 to 400 years, with each storm soaking about 1% of Titan's equatorial regions. Those numbers are poorly constrained, but should set the expectations that Titan precipitation timescales do not need to be earthlike, and are probably much longer, although the driest deserts on Earth may present similar timescales.

There is reason to suspect that at least one kind of fine particulate condensate is drifting downward, covering exposed surfaces very slowly, providing optical depth on a scale similar to that of the rainfall. A rainfall would wash the fluffy condensate downstream, although what the drying process entails is wide open to speculation.

There's no real constraint on how long the near subsurface could remain wet after a rainfall. The Huygens landing site, which was on some of the relatively rare VIMS-dark-blue terrain might even be near the liquifer table.

Another new animation of the last moments of Huygens' descent has been released. http://www.jpl.nasa.gov/news/news.php?release=2013-019. Enjoy.

Wednesday January 14th is the 10th anniversary of the Huygens probe landing on Titan. For those of you relatively new to UMSF blogs you should definitely review the pages of the Huygens News Thread again or for the first time to relive the moment!
Some of my favorite posts are:
#57: concern over the possible loss of half the DISR images http://www.unmannedspaceflight.com/index.p...post&p=4073
#60: tedstryk posts the first incredible image!!! http://www.unmannedspaceflight.com/index.p...post&p=4078
#63: best spontaneous reaction to the image http://www.unmannedspaceflight.com/index.p...post&p=4081
#66 and #67 more great emotional comments on the initial image http://www.unmannedspaceflight.com/index.p...post&p=4084 http://www.unmannedspaceflight.com/index.p...post&p=4085
#78 most convincing interpretation of the initial image http://www.unmannedspaceflight.com/index.p...post&p=4096
#106 first durable post of the surface image by Pando http://www.unmannedspaceflight.com/index.p...post&p=4124
#175: Pando posts a great resource for amateur images! http://www.unmannedspaceflight.com/index.p...post&p=4198
Best video of the landing http://www.youtube.com/watch?v=yrtw7AQ8zMQ (Note the Photojournal article on this is located here http://photojournal.jpl.nasa.gov/catalog/PIA08117 but I can no longer get the Quicktime movie to work.)

New JPL retrospective(also the first time I've seen a movie that blends the surface image with the descent imagery so well):

https://www.youtube.com/watch?v=TMxL3ZhO8A8

Still remember that day.... time flies!