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

Rev 67 Mission description is up!

http://ciclops.org/view.php?id=4887

Quote from the T43 description:
"The RADAR swath will also cross a hypothesized large impact basin that may cover much of Xanadu."



Just when you thought Menrva was pretty big....Titan mighta done got smacked.

-Mike

Xanadu and the regions south fascinate me. This huge mass of karst like dissected terrain covered in bright smurst (?), and then the possible cryovolcanics of Hotei, Tortula, and Tui...

Combine this SAR coverage with T41 and what a treat it will be to see all the data released. HINT HINT to Radar team.

what a treat is in store....

Craig

Wouldn't be a bit surprised...seems like most of the larger ice moons have been whacked pretty badly (Odysseus on Tethys springs to mind). I wonder sometimes if all these big hits were more or less contemporaneous?

If so, what might be very interesting is to see how erosional, subsurface, and of course chemical processes may have altered the scar.

Hmmm ...... I can't honestly say I see a huge impact basin in Xanadu A (unless Hotei Arcus is the surviving rim of it). The big circular tectonic feature B at 0 degree longitude however sure looks like an old impact basin.
Click to view attachment

I agree. I have not been shown the VIMS team's purported evidence for Xanadu being an impact so I am
unpersuaded. Seems pretty unlikely overall, and there is certainly nothing in the T13 SAR to support
that interpretation.

The T13 RADAR swath of Xanadu showed a large number or tectonic ridges (?) in cool-o swirly patterns. The T13 RADAR swath of Xanadu also shows a slightly larger than normal percentage (for an equatorial region) number of putative smaller craters. This would imply that the cratering record is better preserved on this terrain.

My interpretation is that all the swirliness must have happened a long time ago, and then the craters formed with decreasing amounts of crater degradation drama. (Compared to other non-Xanadu equatorial regions.) I suspect Xanadu might be the Titan equivalent of the Piedmont region of the Carolinas. Lots of excitement a long time ago, but then several hundred million years of Not Much Happening. (On Titan multiply the timescale by 10).

So if it was an impact that happened post-swirly time, it should be very obvious, like most of the smaller craters.

It it was big impact that happened pre-swirly time, it could be really, really mangled up, twisted up, eroded out, and totally ch*nked up. It might not be evident by RADAR (or even altimetry).

Even on Earth many of the big impact craters are not immediately obvious. Chicxulub is a great example. Check out the National Geographic article here. And Chicxulub is only 65 million years old. Imagine how difficult it would be to tease out Sudbury or Vredefort crater's structure after a few more billion years of Earth's crustal spasms and surface erosion.

-Mike

I remember seeing the graph once of bombardment intensity as a function of the age of the solar system. (Surely somewhat speculative, and there may be differences from inner to outer solar system, or even the Saturn system vs. the Uranus system, but let's put that aside.) Basically, it's a tale of exponential decay. Every impactor in its planet-crossing orbit had a half-life until it met its doom, and while Jupiter and Saturn clobbered almost everything, the satellites and terrestrial planets got a proportionate, lesser fraction.

So in a nutshell, almost all of the impacts (especially the big ones) ever to occur happened early, and therefore more or less contemporaneously. There must have been, in all such cases, a period of saturation impacting where Copernicus-sized craters happened almost daily and erased one another, not to mention when an Imbrium-sized impact would pave over hundreds of them. The big basins we see are the ones that postdate the saturation period (and crustal solidification, which would have happened almost immediately with Dione and Tethys; slower with Mercury and Titan). In relative terms, we should suspect, yes, that they're all roughly contemporaneous and about 4 GYA.

The oddity would be those cases where big impacts happened later. It must have happened, but it would be the minority.

The other thing is that the Saturn system has an unparalleled density of medium-sized bodies. Catastrophic impacting might have lasted longer there than elsewhere. On the other hand, the tidal forces pulling everything to the equatorial plane should have sharply increased the number of impacts in comparison with solar orbit in the Earth-Mars vicinity. So I guess that not much in Saturn orbit could have lasted past 4 GYA.

Real modeling should give a better answer than any qualitative discussion, but I guess, in a nutshell, that not much was left by 3 GYA to create big impacts. And most of what there was would have been destined to hit Saturn, not the smaller bodies.

I can see Xanadu as older higher ground rather than a basin. Even though it may have more craterform structures none of them look very recent and a few are altered by what is still likely altering Xanadu’s topography namely fluvial erosional activity. This is evidenced (especially the western portion which has possible daily am drizzle) by the many channels with dendritic branches (better known as rivers, see A below) that appear unaltered by craters or dunes and in the central hilly region where short, stubby radar dark channels and elongated possible lakes are found (see B below). These may be sapping-spring-like fluvial alterations. I wouldn't be surprised if Xanadu was riddled with the same channels that Huygens saw in the brighter highlands at the tip of Adiri.
That Xanadu is not covered with dunes suggest its higher ground and must be swept clear of the sintered schizzle falling everywhere from above. Maybe it only seems to have more craters because the sand seas are covering craters on the lower terrain lowering the count there.
Hopefully in a few weeks we’ll have some more interesting images to ponder and speculate about.
AClick to view attachment BClick to view attachment

Being a Titan-o-maniac I like to follow the Titan flyby's by logging on to the official Cassini-Huygens web page and clicking on 'Where is Cassini Now' on the right side panel. This pulls up David Seal's Solar System Simulator and one can usually get a nice appreciation of what an astronaut piloting Cassini might see during the flyby. There appears to be a problem with the Simulator however in that the moon panel appears 'stuck' on Enceladus at 600,000 km or so. I may be wrong but this may have happened weeks ago during a close Enceladus flyby. ??? Does any one else have this problem or know of a fix for it?

Looks like I'm only half correct: the distance from Enceladus changed appropriately overnite; however it's still Enceladus in the encounter window, and with the T-43 encounter just 19 hrs away! We'll see if it changes to Titan today!

There's alredy been a few Titan flybys after the March Enceladus flyby and the view still shows Enceladus. I don't think it's going to change soon. If you want to see Titan instead, use the Solar System Simulator instead.

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):

Click to view attachment

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

Click to view attachment

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:

Click to view attachment

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:

Click to view attachment

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

Thanks! I'll follow things with the SSS link until the Cassini web page is back to Titan.

T43 Raw images are up!

Most of the images posted so far are not using the best filter set for surface imaging (CB3 and CL1 or CL2):

[NAC CL1 (on Filter Wheel 1 of the Narrow Angle Camera) and CB3 (on Filter Wheel 2 of the Narrow Angle Camera)
WAC CB3 (on Filter Wheel 1 of the Wide Angle Camera and CL2 (on Filter Wheel 2 of the Wide Angle Camera]).

There is a really nice raw image showing the detached haze layers. W00045323.jpg

Here is a negative image contrast-enhanced and annotated. It looks like there are at least two detached haze layers nicely visible in the image. The gap seems a little bigger and more obvious in the upper (= N?) portion of the image:

Click to view attachment

-Mike

[EDIT: added filter wheel information of NAC and WAC]

I took this image and contrast-enhanced it even more and it appears that there might be yet another bright layer in the inverse image just above the dark layers in the inverse image. (Inverse image bright = normal image dark)

Click to view attachment

(Could this be just an artifact? compression effects, the contrast algorithm, instrument effects, etc.)

I carried out a similar inversion and contrast enhancement with PIA09869 - Violet Titan.
The same layer is there as well:

Click to view attachment


-Mike

"Natural" color composite of Titan from the T43 flyby:

Click to view attachment

Detail of Haze layer in "natural" light (on left: RGB) and using other channels [right: R= RED; G = BL1; B = VIO]

Click to view attachmentClick to view attachment

-Mike

Mike’s negative image enhanced views and ‘natural light’ images of the detached haze layer(s) (upper left in my composite image below) and the ‘cow lick’ top portion suggests we’re looking at the haze layers near Titan’s N polar active region. As the T43 images are relatively low resolution it helps to look other images from other flybys of the detached haze in the N polar region in much higher resolution and dedicated to showing the details. In the 3/16/06 view (lower left) the ‘cow lick’ is really unruly and perhaps some 5 atmospheric haze layers are visible. The darker polar hood also shows in that view. In the extreme color enhanced view of 3/31/05 (lower right) some 10 layers are visible. Its fun to look way back to the Voyager 1 discovery images of the detached haze layer (the upper right 8/23/81 image) and see similar features especially the distinct detached layer and the dark polar hood. It will be interesting to watch these seasonal atmospheric phenomena change as Titan's northern spring progresses over next 5 years. Of interest the Voyager 1 flyby occurred about 27 years ago about 2.5 years less than a Saturn ‘year’ and so that image shows Titan as it might appear to us 2.5 years from now. Past research with Hubble Space Telescope images from the period 1990-2004 by Ralph D. Lorenz, Mark T. Lemmon, Peter H. Smith and G. W. Lockwood suggest we will see the N polar hood disappear and one develop in the South polar region over the next 7-10 years.
Click to view attachment

I made an animation sequence showing the limb haze layers during the Cassini T43 flyby departure from 112,000 to 163,000 miles (12 images):

Click to view attachment

These were taken using the UV3 filter on the Narrow Angle Camera

Enjoy!

-Mike

Nice animation! Looks like the different filters put a different "face" on the N polar region with the CL1-VIO showing the NP Hood and the CB3-CL2 revealing a possible NP cloud edge.
Click to view attachment

Tectonics on Titan - Titan flyby on May 12, 2008.

http://photojournal.jpl.nasa.gov/catalog/PIA10654

And a new crater in Dilmun!

http://photojournal.jpl.nasa.gov/catalog/PIA10655

Impact Craters
http://photojournal.jpl.nasa.gov/catalog/PIA10655

This crater is located within Juramike's favorite feature, the Spaghetti Monster. Crater not clear in ISS images, so no albedo markings are associated with this feature.

The ridges in the other released cutout were seen in the T20 HiSAR swath (I think that's T20) anyway.

The matching wiggles in the lower two ridges are quite eyecatching.

It's not my fault. [ducks]

Click to view attachment

Here is my estimated position (somewhere in there) of the Dilmun crater. Right inside the funky feature far to the N of Adiri (Spaghetti Monster, Dancing Monkey, Squiggly Thing, etc.)

Click to view attachment

Many way cool things around the crater (image above). The downwind side of the crater appears RADAR smooth dark. In addition, there are symmetrically placed bright patches on either side of the craters wind shadow. RADAR-brighter (rougher or fluffy) windblown deposits?

What is NOT observed is also interesting, this SAR image should be smack dab in the middle of the Dancing Monkey (Spaghetti Monster feature). So while by ISS it is evident, by RADAR it is subtle.

One subtlety is a long RADAR dark streak bounded by very slightly RADAR brighter mateial. This is indicated by the red arrows. This might be the origin of the ISS-dark streak.

Click to view attachment

The T21 RADAR swath had similar features (above) that seemed to coincide with the ISS-dark polar lanes (Polar Stripes) in the polar region of Titan. The two features might be similar.

The Dancing Monkey (and Polar Stripes) features might both be graben that have been infilled with wind-sorted material. The finer, smoother stuff is RADAR dark and ISS dark. Alternatively, maybe organics in the graben bottom may be responsible for the dark color.

-Mike

It's probably nobody's fault.

That's location is correct, juramike. The crater is in bright terrain. A bright-dark boundary is just to the northwest and southwest of the crater.

Oh, I just realized that the 3 parallel ridges west of Xanadu have already been imaged by RADAR during T20 distant look :

http://pirlwww.lpl.arizona.edu/~perry/RADA...01_T020_V01.jpg

Even if the resolution is quite lower, is it possible to make a stereo picture to determine the 3D structure of the ridges ?

.

It’s a pity Cassini can’t be put into a polar orbit around Titan so that areas of interest can be viewed repeatedly and topographic maps constructed to help confirm implied topography from the SAR images. There is a topographic map of ‘Kodiak’ island and nearby polar sea and river eroded landforms as shown in 1) below. The ‘ridges’ you have identified donot stand out very well on the topo map. This may result more from the lower resolution of the topographic map. Alternatively the ridges may just appear as such and not be linear tectonic elevations like the ones just imaged in Xanadu. By examining the drainage patterns of the rivers one can infer some topographic sense of the land drained. In this case the drainage pattern supports the notion the ridges are higher ground. They are somewhat wavy and don’t sport tectonic fracture so they may have been formed differently.

1) Click to view attachment

Ahhh, but just slightly to the S of the image above (and just barely missed by the PIA10353 topgraphy overlap) is an area that has very long parallel streams.

These streams were previosly mentioned in the Titan's Lakes Revealed thread, post 252 (link here) and also in the T28 Flyby thread, post 75 (link here, note Olvegg's indications of directional flow, this must have a really interesting dynamic!)

Click to view attachment

These streams do not branch very extensively and seem set in their little valley. (Compare with the dendritic set just to the NW). The two running alongside each other look like a great candidate for river capture, so something must be keeping them from apart.

I would assume that the streams are sitting in NW to SE trending creases (under tectonic control?). The topographical image PIA10353 just shows that the downstream part is at the most only tens of meters different in elevation. According to the topo image, any ridge in the downstream section between the two streams could only be 10's of meters high at the most, so to topography here is subtle.

-Mike

Most interesting! The rivers of PIA09217 (T28 SAR) are my favorite! The topographic map catches them in their lower reaches where they are distinct and fairly straight running in a low relief partially flooded plain. Their upper reaches show tributaries with greater tortuosity draining regions that have greater apparent topographic variation and elevation (SAR appearance only). The presumption is they are flowing full with the seasonal polar monsoons raining liquid hydrocarbons. While the lower reaches are fairly straight and perhaps are confined to tectonic wrinkles they are not as straight as other channels that seem to occupy tectonic faults as shown in the images below.
Click to view attachment Click to view attachment

I wonder if some of the low wiggly ridges pointed out by Gladstoner are eskers from a previous climatic period of colder polar conditions.

I lined up some of the features indicated by Gladstoner, titanicrivers and myself onto the North Polar RADAR Swaths graphic PIA10008:

Click to view attachmentClick to view attachment

Ridges, graben, and presumed stream divides are indicated with a black line.
In dashed blue are close alignments of lake chains. (In one case in T19 the lake chain direction lines up nicely with stream divides).

The graphic on the right is the same image with much of the extraneous stuff removed for clarity.

There could be a pattern...(or two)

The T29 RADAR Swath will be key.


-Mike

Mmmm . . the patterns appear to follow the swath directions. I'm sure you've eliminated obvious artifacts, but even so it makes me wonder if along-swath ridges are picked out by the radar better than ones at other angles.

"it makes me wonder if along-swath ridges are picked out by the radar better than ones at other angles."

That is absolutely true and a well known problem in SAR interpretation. Not just SAR - all linear relief features are best seen if illuminated perpendicular to their long dimension in all images - I'm seeing the same on Eros now. Since SAR is illuminated from the side, the above statement follows naturally.

Phil

I agree. I was really looking to find somewhere up in the polar regions where the ridge/drainage/graben pattern was perpendicular to the swath direction.

Only the T21, T25, and T28 regions in the lower-mid latitudes have a clear ridge pattern at a steep angle to the swath direction.

This is another reason why the T29 Swath would be key. It would help confirm the continuation of the v. slight off angle pattern of the left polar section of the T28 Swath (where there appears to be tectonic/fault control to the stream drainages as titanicrivers pointed out) with the area of the T19 Swath.

A perpendicular swath across one of these tentatively identified ridge/drainage/graben patterns would also help confirm that it's not just an angle effect. Maybe in the XM? (XXM?) ((3XM?))

-Mike

T43 - Equatorial Anti-Saturnian hemisphere (Dilmun, Northern Shangri-la, Tortola Facula, Central Xanadu)
Click to view attachment

and T43 - Targeted Distant look (Western Tui Regio)
Click to view attachment

Dang -- unfortunately hard to see much in the distant view here. We need high-res, either VIMS or RADAR, I'm not particular! Okay, yes I am. Lets try VIMS

- VIMS Jason

T43 SAR RADAR Swath released as PIA12988