[X] My Assistant

[Juramike]

T43 Mission description is now up!

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

Some highlights:

• Radiometry of western Fensal-Aztlan (will fill in a big chunk of the radiometry map)
• SAR RADAR of Tui Regio in Xanadu and Tortola Facula as well as a very interesting piece of terrian in NE Shangri-La. (Lotsa bright-dark boundaries, maybe some cool islands, dunes, "shallower" areas ) Also some imaging over Dilmun.
• Cloud imaging by VIMS and ISS observations

-Mike

[Juramike]

My impression is that central Xanadu and central Adiri are similar in many ways.

Craters – numbers similar, erosion state similar, but degraded crater aspect different.
The visible impact craters (my personal speculation) have a different aspect in Xanadu. The Fresh crater pretty much similar (entry 4 in Post 2, Erosion on Titan thread, link here). However, the outer rims of Degraded craters seem more distinct and sharp-edged by SAR Radar on Xanadu (entries 34, 35, 36, 37, and 40, Post 5, Erosion on Titan thread, link here) than compared to Adiri. My speculation is that the erosion environment or material composition/structure is different on Xanadu compared to Adiri.
The overall crater counts and erosive state (again, my speculation) on both Adiri and Xanadu support that both surfaces are pretty old (since you do see about the same crater population), and both have been subjected to intense weathering. It is just that the erosion “style” on Xanadu appears different.

Tectonic ridge patterns – swirly shapes very similar
Like in central Adiri, in central Xanadu there is an overall trend of steep ridges and valleys/basin to be trending EW - much of it looking like the “ski tracks” of Adiri. There also appears to be repeating ridges and valleys trending NW-SE and in the western part of Central Xanadu some ridges/valleys run NE-SW. Overall, the pattern is pretty complex. [Adiri is more simple: EW trending tectonic ridges, with a N-S undulation pattern].
Xanadu also has a very similar pattern to the concentric ridge/basin structure surrounding the “shark fin” feature of central Adiri. The graphic below shows the shark fin of central Adiri (seen in PIA03566):



And the graphic below shows a similar feature in central Xanadu (seen in PIA08532). It is about the same scale.



For grins and giggles, I rotated the Xanadu feature (and flipped it about the horizontal axis) to try and line it up to the Adiri pattern:



And for even more fun, I rotated, rescaled and grafted it onto the Adiri feature in a split screen (on the left is Xanadu an on the right is Adiri). They match pretty well:



Whatever was responsible for the tectonic ridges and swirly patterns on Adiri, seems to also have operated on Xanadu.

Valleys different
Adiri clearly has dune sands that have invaded and filled the basins between the ridges. Xanadu still has more RADAR-bright valleys with no evidence of dunes filling the valleys. This could be due to topography , if overall Xanadu is higher than Adiri. Or it could be due to isolation - the W Xanadu terrain (clearly different from central Xanadu) isolates the region (topographically? large pits acting as sand traps?) from saltating dune sand particles. Altimetry will at least show if Xanadu valleys are at the same height as Adiri basins (or at least relative to Shangri-La basin).

Xanadu vs. Adiri - Different stuff?
A big difference is in scatterometry and VIMS. VIMS shows Xanadu to be very bright, with Hotei Arcus and Tui Regio seeming to be very different from other portions of Titan. However, 5-cm bright terrain has recently been found partly covered in dunes in NW Fensal
Radiometry and scatterometry shows Xanadu to be very different from Adiri. It has a very low brightness temperature (low emissivity, radiometry dark) and has a large radar cross-section (high scatterer, scatterometry bright). Together, this implies a higher amount of volume scatter for Xanadu compared to Adiri. These result imply that the two terrains are materially (or structurally) very different.

One of the really exciting things happening during the T43 flyby will be the radiometry of the E portion of Xanadu and W Fensal/Aztlan/Quivira/Tseghi). This will fill in the radiometry map and help show differences and similarities between Xanadu, Quivira and the VIMS 5cm-bright material in NW Fensal. Unfortunately, radiometry data is usually only released in publications so it may be a while before we see the results.

Overall, while Xanadu may be made of different materials and might have a different coating compared to Adiri, the forces that acted upon the two terrains seem similar.

Even though Xanadu is “weird”, it’s not too weird. I think these latest few flybys (T41 and T43) will help fit Xanadu in to the rest of the Titan terrain.
-Mike