[X] My Assistant

[ngunn]

We discussed this briefly before in the "Equatorial Sand Seas" thread, posts 252 to 257, so I will understand if there are few further comments, but drawing from some recent abstracts there is now more to say so I thought I'd start a separate thread. First the neutral assessment of the issue that concluded those earlier deliberations:

QUOTE (rlorenz @ Feb 9 2008, 02:59 PM)
I dont see a strong case yet for any large-scale re-orientation (don't see a case against it either)

To summarise the issue as I see it:

The surface of Titan (like some other moons) is thought to be mechanically decoupled from the interior by a subsurface ocean. Unlike the other 'ocean' moons, Titan has highly active surface processes including fluid flow and solid mass redistribution. Deposition of material from the atmosphere is thought to favour the polar regions. We observe regional slopes, large scale lake basins, mountain chains (with preferential E-W orientation) and possible faults that could in part be maintained by migration of the entire crust with respect to the rotation axis. A testable prediction can be made: Titan's surface formations will be found to include some that originated far from their present latitude.

Now, what's new?:

http://www.cosis.net/abstracts/EGU2008/101...008-A-10189.pdf
Lorenz, R.; Stiles, B.; Kirk, R.; Zebker, H.; Callahan, P.; Radarteam, T.C.
Geophysical Results at Titan from Cassini RADAR : Topography and Spin State Overview

Note the last paragraph. Even the wind could be 'torqeing the surface around'.

Also relevant though not specific to Titan:

http://www.cosis.net/abstracts/EGU2008/013...008-A-01318.pdf
Harada, Y.
True polar wander due to surface mass loading: Interaction between rotation and deformation through pole tide

I'll leave it there for now to see if others have comments.

[Juramike]

More on the polar wander of Titan. Implications that the surface is decoupled from the core and slipping around on a subsurface ocean.
(Still no numbers on the size of this effect, however, but it is visible in RADAR swaths not lining up.)

Space.com article: http://www.space.com/scienceastronomy/0803...itan-ocean.html

From the article, Titan's crustal thickness: 50 - 150 km thick
Subsurface ocean thickness: 100 - 200 km thick


[Editorial aside: This puts Titan's subsurface ocean only twice as deep (and twice as far) as Europa's subsurface ocean.]

-Mike