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Huygens News Thread, News as and when we find it
Juramike
post Feb 13 2009, 05:01 AM
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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):
Attached Image


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


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ngunn
post Feb 13 2009, 11:16 AM
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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?
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Juramike
post Feb 13 2009, 01:14 PM
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Here is an enhanced-contrast B&W crop of PIA08115 in 5x Tall-o-Vision:
Attached Image


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


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Juramike
post Feb 13 2009, 01:36 PM
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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):
Attached Image


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


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ngunn
post Feb 13 2009, 03:04 PM
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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 . . smile.gif
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Juramike
post Feb 14 2009, 09:30 PM
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Closer and closer....details of the channel muds.
Pseudocolorized version of a flattened crop from the DISR mosaic PIA08114:
Attached Image


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:
Attached Image


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


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Juramike
post Feb 17 2009, 03:27 AM
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Pseudocolorized version of a flattened crop from the DISR mosaic PIA08114:
Attached Image


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:
Attached Image


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


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Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Juramike
post Feb 20 2009, 03:53 AM
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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:

Attached Image


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


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Juramike
post Feb 21 2009, 03:05 PM
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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:
Attached Image


E Adiri and Anitilia Facula, Titan compared to NW Anatolia and the Aegean sea on Earth:
Attached Image


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):
Attached Image


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

-Mike


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Juramike
post Feb 24 2009, 03:53 AM
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Zooming in and comparing the HSL with the ancient city of Assos (across the strait from Lesbos Island):
Attached Image

(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.
Attached Image


Closer in, the marina structure is about the same size and shape as the "castle" in the Huygens DISR images:
Attached Image


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:
Attached Image


-Mike



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HughFromAlice
post Feb 24 2009, 01:22 PM
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QUOTE (Juramike @ Feb 24 2009, 01:23 PM) *
Zooming in and comparing the HSL with the ancient city of Assos -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.
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Juramike
post Feb 25 2009, 11:42 PM
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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


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Juramike
post Mar 15 2009, 12:47 PM
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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):
Attached Image


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)



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Juramike
post Mar 15 2009, 12:57 PM
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Here's a graphic that lights up the RADAR-dark/ISS-bright terrain near the Huygens Landing site:
Attached Image


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.


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Juramike
post Mar 15 2009, 01:12 PM
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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
Attached Image


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???)


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