Pish...day after day sitting at work, pressing the refresh button while waiting for someone to answer the phone and yell at me, and finally the wait is over. With our mysterious Raw Image Page code monkeys back to work after what I'm sure we all hope was a fine holiday, at last we gaze once again upon the face of Tethys, a moon that's likely sick with envy for all the attention her diminutive plume-blastin' brother has enjoyed lately. Here's the 24 November encounter mosaics combined in a slightly fictionalized format, with all the usual positional errors and distortions. Don't come crying to me if the Ice Dingoes eat yer baby because you camped in a duplicate crater I made.

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Yes, there's always more...the portion of the Ithaca Chasma that wends it's way over the north pole past Telemachus has been hard to make out. The distant opnav images have done a fine job this year on a couple of occasions.

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Here's another view of the northern latitudes from the 25 September flyby, also cosmetically enhanced. I'm pretty sure Steve used these images in his recent map.

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Dear ones, I leave with you an image I think conclusively proves that Melanthius is a double impact structure (9-11-08), and also with a riddle for Dr. Stooke. Why does this hemisphere that features Penelope and its neighbors have the appearance of relatively smooth plains pitted with deep craters while so much of the rest of Tethys has a much more lumpy and ravaged look? Dione seems to have similar regions.

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There will be a global-view poster from images taken this year in the thread later as well.

Goodnight, all!

Well, EC, the high resolution images of the "lumpier" terrain looks to me to be covered with linear ridges. There are a wide variety of orientations, and they're best seen near the terminator. But there are surely parallel linear ridges all over the place. And while some do seem to have been disrupted by small craters, some of them neatly align strings of craters, craters of almost identical sizes that are exactly as wide as the distance between the linear ridges and that are arrayed in strings between the ridges.

It happens so frequently I have a hard time believing it's all happenstance. Those crater strings are endogenously controlled, I'd bet the farm on it.

-the other Doug

EDIT: Here's a subframe illustrating what I'm seeing:

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dvd

Aye, I'd be inclined to agree on most accounts. I'm still curious as to the why of the apparent global dichotomy though. There are quite a few small linear features I'd be hard-pressed to explain away as random, and they do seem to be concentrated in the lumpy places ( I think they might be crude baby versions of the seemingly infinite tiny crosscutting fractures on Dione somehow). There are similar small-scale linear marks on the surface of Rhea, as you've surely noticed.

I notice you have some affinity for crater chains, Odoug. ( I think you're right about Rhea too). I personally see basins a lot myself (usually illusory), but your perception of linear features seems to bear out a lot of the time. I look forward to other views too.

Weigh in, folks. Is Tethys doing lines?

the tethys dichotomy was in fact noticed 20 years ago by jeff moore, among others, from voyager data. this is in fact born out by topographic mapping too. its origin is still a complete mystery, but is most likely ancient resurfacing or seismic shaking and disruption due to Odysseus, which is located on the opposite side of tethys!
paul

As Dr. Exploit points out, there's a patch of smooth plains material on Dione as well. Some kind of resurfacing seems to have occurred on both bodies, in each case limited to a single region. On Tethys it might be considered to be Odysseus antipodal terrain, but one would want to compare crater counts in the basin + ejecta and in the plains to see if they are similar in age. On Dione there's no suitable antipodal basin. I personally favor some kind of cryovolcanism - in fact I'm thinking of doing an LPSC poster outlining my thoughts on this. There seems to be more evidence for that on Dione, and none on Tethys, perhaps because the event was older on Tethys. By cryovolcanism I may be referring to surface flows occupying a depression, or some kind of terrain softening caused by subsurface heating without surface flow, I'm not sure.

Phil

Dr. Exploit... all I can say is "more please".

Craig

Has anyone expounded on the possibility of extreme seismic disruption causing the lineated-but-chaotic features seen on Tethys? A major impact would release P, S, and surface waves of extreme magnitude, and might provide enough energy at wave reinforcement points to fracture or partially melt the material in the upper layers.

this was indeed looked at in a paper by jeff moore and others in icarus 2004. i dont recall what they concluded, but it is possible.

I'll have to get me an Icarus Subscription....


Another possible source of the huge areas of "lineated surface perturbations" might be forces from tidal friction and distortion induced by the changes in the rotational and orbital motion of Tethys by the big collision. The collision almost certainly was off-center enough to impart rotational energy, and if might have been enough to induce rotation in Tethys, which might have taken a while to damp down. At least a whopping libration.

Orbitally, almost any collision would have added eccentricity, with its variable tidal bulge to dissipate. (Non-Saturn-Equatorial-plane perturbations also would yield some dissipation, but this I think is the weakest.)

As to what might have caused the actual form of the huge canyon system, one can speculate about the displacement, distortion, and subsequent relaxation of a small rocky core at the center of Tethys...

-- MarkG

Assuming there IS a small, rocky core considering Tethys' low density.

A 100km radius core of 3 g/cc density (i.e., a small rocky core) would only amount to 2% of Tethys' mass, and not much of a change to its overall density, but could influence the course of its dynamics.

The presence of the two trojan companion moons Telesteo and Calypso are also a smoking gun for a severe disruption of Tethys in the past.

Yar!

Thanks for the replies and discussion all. The CIRS ride-along from the recent periapse is down and presented side-by-side here. I think these might add something to Steve's map!

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This is above my pay grade, but I think those lineated features look a bit too fine and fresh to have resulted from a really big impact (a la Odysseus).

This isn't from this year, but it does look at some of the same territory. It's a mosaic of high-resolution regional images from the 27 June 2007 encounter, and includes some of the linear features under discussion in this thread. A more accurate version is included in the latest official map and atlas, but I think this is an improvement over the mosaic posted in the earlier discussion (this is for your compliment, Craig

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*sigh* Time to get back to other obsessions. I plan to spend the evening with Mr. Jameson bawling my eyes out over all those Everett-Interpretation copies of myself that got run over by cars tonight on the way home from work, to the tune of "Fake Plastic Trees". Look both ways before you cross the streeet, loves.

An infinite number of me really got that remark, and found it hilarious. Another infinite number of me just sat and scratched my head, wondering what you meant. Yet another infinite number of me never read it...



-the other Doug

I have beer and/or whiskey pouring out of my shcnazz, odoug. Note that mandy does't claim to agree/disagree with said propsition, as it would reuslt in wavefunction collapse (or the appearance thereof). Ten to the hundredth djellisons will branch off of this thread putting the smackdown on the deviation if I fail to redirect, and rightly so, resulting in infinite additional threads. (trying to hold my water now ) Thanks for the adknowlgement nonetheless. You made my night. Seriously folks, no more on this subject in this thread, please (my bad) or Ms. Tethys will be in trouble.

Redirection commences in 3/2 2/1 1/0....

For the Rose and the Tower! Say thankya.

We have normality. We have normality. Anything you can't handle from this point on is your own lookout.

Now -- off to find a really *hot* cup of tea!



-the other Doug

Dear Dr. Exploit..... all I can say from the infinite numbers of me iiiiiiiiiiiiis THANKS thanks thanks thanks thanks.......

As for the "lineated surface perturbations", might they be icy expansion ridges, kinda the reverse of the compression ridges on Mercury? Tethys had to expand its volume as it froze. Or might there be cyclic periods of thaw freeze as tidal cylcles change between the moons.

Hmmmmmmmmmmmmmmmmmmmmmmmmmmmm to infinity...

Now must crack open the beer (after that shot of Jack) and tackle an infinite number of cat boxes!!!!

Keep all you selves safe!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Redirected....

Craig

Exploitcorporations....

there is no pay grade for your work... I know it comes from the head and heart and is worth pure platinum.

Looking at Tethys and the other mid-size icy moons ... Saturn, the rings, and mooms and mid-sized moons and moonlets, Titan, and strange sponge that is Hyperion tumbling before the sublimating walnut that is Iapetus....the whole Saturn system has to be looked at together. There is an interlocking story here, and the peices can not be deciphered in isolation.

So keep those mosaics coming.... and databit by databit, the jigsaw will be revealed.

Cheers!

Craig

Good call Dr. Exploit about the Tethys images on my map. I did indeed use a portion of the Sept. imagery, namely the eastern side. So perhaps the western side could be added to gain some further coverage, and/or the more recent Dec 9 images that you posted.

Your 2007 hi-res mosaic is pretty neat and looks like it was used to good effect in the official map.

Steve

And here it is with the added images, a raw image from Sept. and Exploit's from December...

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Full res at http://laps.noaa.gov/albers/sos/sos.html#TETHYS

This shot is just plain cool!

Yeah...so is that!

A cool shot indeed, Ted.