Here is my first attempt to map Titan's channels.
It's part from T44 SAR image (I think southern Xanadu is on the image).
It's not final version. Some channels are not interconnected and some channels are not marked at all.
Especially I have problems with dark/bright channels connections. Some bright channels evidently turns to dark channels and dark channels turns to bright channels.
I think that this is caused partially by topography (canyons ?) and partially by different bed (bright - ice pebbles, dark - organic mud ?).
My next problem is prominent topography which masks some channels.
Marked features:
Dark channels - light blue line
Bright channels - green line
Uncertain channels (dark/bright) - dotted line (light blue/green)
Circular objects - dark blue line

Image has reduced size to 50%.

Nice!

Can you post a context image to help locate this on the Titan globe?

How about this map from the Stiles et al paper. It has some topo info too that might help one deduce the direction of flow in some channels. One large channel at -20 S and 120 W appears to be at one of the lower spots on the downsloping mid portion of Xanadu.
http://dx.doi.org/10.1016/j.icarus.2009.03.032
Click to view attachment

Try Jason's page:
http://pirlwww.lpl.arizona.edu/~perry/RADAR/#T44

This swath is approximately at center on Jason's map (It's middle of three long dark swaths).
Image is east part from this swath.

Whoa I'm late

Thanks titanicrivers! Altimeter data, that is what I need.

Might be of interest (especially figure 2), check out:

Langhans et al. LPSC 2010 Abstract 1709. "Valley formation from methane convective storms on Titan"

Thanks Juramike!

Second image from T44 swath. It links to previous image.

Animation showing possible channels and ancient lake on T49 swath.

Localisation on Jason's map - coordinates (1180;1340) pix, below Belet regio.
http://pirlwww.lpl.arizona.edu/~perry/RADA...0_map_RADAR.png

May want to use this link instead.
http://pirlwww.lpl.arizona.edu/~perry/RADAR/
and this one which labels the T49 swath on a grid map.
http://www.unmannedspaceflight.com/index.p...st&id=19154

There may be a topo overlap here:Click to view attachment

Not sure if this is the proper thread, but major congratulations to Juramike, Bjorn & Doug for their headline story today on the JPL site (also citing UMSF!)

http://www.jpl.nasa.gov/news/news.cfm?release=2010-078

That's the 2nd official mention of UMSF I've seen today, the 1st being New Horizons front page. Certainly speaks volumes about the quality of knowledge in here!

Back on topic, about how much of Titan's surface can Cassini map with SAR until EOM? I haven't seen a percentage anywhere.

Gotta add my congrats as well ! Its gratifying to see this work of dedicated volunteers so honored.
Re the proper thread: I'd suggest putting this is the 'Labyrinths of Titan' on p.2 as post #7; this is where this story of Mike's began!

Congrats, guys!

Hat's off to the "volunteer researchers." You guys rock!

Congrats indeed!!!!!!

Craig

An intriguing possibility!!!
This area south of Belet was also very near the origin of the explosive April 14-15, 2008 tropical storm on Titan (documented by Schaller, Roe and Brown using Gemini N). T 49 collected SAR data some 8 months later from this region. Shown below is the same region as your channels image but with artistic enhancement of some smoother darker regions ... could these be playa from that storm ???
Click to view attachment

Sorry Titanicriver, but last time I didn't notice that you posted animated Gif!
I looked at original T49 radar swath and in different parts of this swath these areas are more prominent. Mostly they are between bright regions (presumably ice hills) and smooth plains. So if smooth regions are really parts of the dry lake, then they can be some kind of coastal organic mud or so (wet after storm). But it's only my personal opinion.
We need more radar swaths from this region!

And I send another radar image with marked channels, now I measured lengths (in kilometers).
Localisation:
(10S;140W) or
(2475;1220) on the Jason's map http://pirlwww.lpl.arizona.edu/~perry/RADAR/

Really, really nice synopsis of an article explaining Titan's RADAR-bright channels by Emily:
http://www.planetary.org/blog/article/00002478/

Absolutely agree Mike. Great paper by Le Gall et al and discussion by Emily.
The 2009 LPSC abstract is also fascinating to read. http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1533.pdf
Another interesting link is to the LPSC 2010 paper by Langhans et al. showing an interesting terrestrial counterpart of the Titan channels discussed in the Le Gall paper.
http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1709.pdf

I haven't seen the full paper but Emily mentions the low radar brightness at the Huygens landing site as one thing that doesn't fit perfectly with this picture. I think that's not so much of a problem because the pebbles at the two locations could be compositionally different. Flowing liquids will make pebbles out of whatever you throw into them. Regrettably, on Earth's beaches you can now find pebbles of tar and pebbles of plastic lying among (or more likely on top of) the usual rocky kind. The Huygens pebbles could be less transparent than the ones from Xanadu, or more aerated with a lower refractive index, or predominantly made of a different material altogether.

I wonder what a material covering or coating the cobbles would do to the RADAR return? (Like how visually dull muddy cobbles appear)

While you're there Mike (or anyone): Do you know if there is positive evidence yet for the Huygens pebbles being made of 'dirty water ice' as stated in the LPSC abstract above? Maybe a paper I missed along the way? Or perhaps new information in the pipeline coming from the VIMS landing site closeup? Or is it still just a working assumption?

On the coating question I would have thought an organic coating would be pretty transparent to RADAR, likewise any small organic inclusions within an ice cobble.

The dielectric constant measured in the Huygens landing area is too low for ice. So it implies some sort of ice/organic mix. (The organic component would bring the dielectic constant down.).

If I understand the dielectric discontinuity explanation in Emily's blog, an organic coating might make an extra dielectric change, going from low to high as you go from the organic coating to the ice cobble. (But I haven't read the paper yet so I'm speculating wildly)

I would also suspect the density of the cobbles and the duration of time they have been exposed on the surface makes a difference in the radar backscatter intensity. Huygens' cobbles are only a fraction (area wise) of an otherwise darker smoother material that may mix in a lower backscatter factor. The cobbles in Xanadu's bright channels may be jumbled together without much intervening darker substrate and so have a higher radar backscatter and dielectric constant.
Xanadu's channels may be of differing ages (the middle one of the figure below may be older) and perhaps lose their brightness over time as they weather and are covered by atmospheric fallout.
Click to view attachment

Depends how thick you think the coating might be. Unless it's at least a significant fraction of the RADAR wavelength I don't see it making much difference. I could be wrong though!

Edit: Good points also TR.

I love the idea of deposits of ice cobbles acting as RADAR cat's eyes, but I read very recently** that surface exposures of water ice are pretty rare on Titan. That could mean that the Xanadu channels are not typical of pebble banks elsewhere on Titan. A match with the Huygens site maybe shouldn't be expected.

**EDIT - from the latest CHARM presentation:
"Sinlap crater is one (only) place on Titan where dielectric constant and IR spectra are correlated and suggest enrichment in H2O ice."

Do these channels represent a second such location?