[X] My Assistant

[volcanopele]

The next Titan flyby is a little over a week away but it is never too early to think about it. The Looking Ahead page for Rev44 and the T30 flyby is now posted:

http://ciclops.org/view.php?id=3026

Rev44 on the whole is pretty quiet. The T30 flyby will be especially important for RADAR. The first half of the C/A pass will be dedicated to altimetry, giving RADAR their longest altimetry swath obtained to date. This swath is intended to validate their "TOPO from SAR" method of deriving altitudes. This method uses the central beam in SAR mode as a side-looking altimeter. The T30 altimetry swath will cover a number of previous SAR swaths, allowing for validation of the altitudes derived from those passes. The second half of the C/A pass is dedicated to SAR. RADAR will image the central and southern portion of the Caspian Sea (the Cassini site got it wrong, T28 was never adjusted and looked at the northern part, just like T25).

[alan]

the Cassini site got it wrong, T28 was never adjusted and looked at the northern part, just like T25

I suspose that explains why we haven't seen part of the SAR from T28. Nothing dramatically new to show the general public.

I like the new mosiac, particularly how its been combined with last years imagery.

[Guest_AlexBlackwell_*]

The mission description document is now online (1.1 Mb PDF).

[alan]

Images from T30 are up, just wide angle camera so far. Some clouds visible in the south:
http://saturn.jpl.nasa.gov/multimedia/imag...0/W00028136.jpg

[ngunn]

Some great images -here's eastern Adiri:
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=110601

And the crater to the north:
http://saturn.jpl.nasa.gov/multimedia/imag...iImageID=110568

[Floyd]

The recently returned UV3 images show the weather on Titan quite well. In a series of images, a little vortex can be seen to move from the 10 o-clock position shown here, to out of view in the west. The series would make a great movie.



Floyd

[remcook]

are you sure that's not a dust speck? I don't think I can see any vortex, just layers

[djellison]

That's a classic dust spec.

[Floyd]

It may be a dust spec, but it moves, check out these 4 images (1 from each page of about 3 UV3 images):

one

two

three

four

Could be a dust spot if camera was drifting ever so slowly?



Edit: Damn! It is a dust spot. It stays steady in the frame and Titan moves.

[ugordan]

It's a dust ring, no doubt about it. Notice the hot pixel immediately below it, the ring stays fixed w/respect to it. If you flip those frames as an animation you'll see Titan's disc drifting, but the ring stays fixed on the screen.

[elakdawalla]

The T30 radar swath (half-swath actually) has been released.

http://photojournal.jpl.nasa.gov/catalog/PIA09218

--Emily

[Juramike]

There are some puzzling features in the T30 RADAR swath.

In the far western part of the swath, the dark sea and features leading into it look nice and "normal". (Deeply eroded ridges and streams that were then flooded by the hydrocarbon lake to make a pretty fractal pattern). There appears to be an E-W ridge line cutting long the western portion of the image.

But next to this is a funky looking embayment with strange surrounding features highlighted in the images below.



The bay portion does not have the dark deep smooth look that the other fractal embayments have to the west. Instead, it appears bright (rough) and cut by thin dark channels. (My mind immediately jumps to images of frozen bays in Earth's arctic, with pack ice jostling around and making rough berg fields). Could this be a field of relatively rough organic scum all packed together? Or could it be a field of dried out bay and crusty stuff coating the drying shallows?

Looking at the ridge pattern running roughly east west (pretty much like we've seen everywhere else on Titan), we would assume that the area near the bay is pretty flat and shallow. This is also evidenced by the shoreline (medium bright = land, more bright = shore) having a smoother outline and not so fractal-like. So maybe the dark channels in the crusty zone are where streams have cut through the "stuff" (whether floating or not).

Oddly enough, even though this region seems flatter, the streambeds in this area, indicated by orange arrows, are bright (rough) compared to those in the highlands to the west (indicated by blue arrows).

Maybe the stream boulders gravels are not made of water ice, but of organic shizzle chunks [don't use past tense at UMSF!] that have been carved from the surface and floated/plopped along the streambeds?

Even stranger, there is an area that looks like a type of chaos terrain (red dotted square), where the streams form a web-like network before flowing down towards the bay. This area is parallel to the tectonic ridges, so it could be a low rise or divide. Check out how the streams on both sides of this divide seem to connect. Alternatively, it could be an area with cracks in the surface shizzle making some type of wierd highland swamp that drains away on either side. It almost forms a polygonal network.

(I keep using the snow analogy for the organic shizzle-deposited areas - it seems to work, but it's important to remember that unlike snow, organic materials on Titan won't melt and might not even dissolve!)

What gives?

-Mike

[nprev]

Mike, in your right-hand image (the close-up), to me those look more like the boundaries of lobate flows (or eroded layer segments) than they look like streams. In a way, this reminds me of the 'pancake domes' of Venus, actually. The chaotic area would therefore be an area of intense erosion, cause unknown.

Just an observation. If I could claim with absolute certainty that I knew what was going on down there, I'd already have purchased my ticket to Stockholm...

[rlorenz]

There are some puzzling features in the T30 RADAR swath.

Indeed. And in TA, T3, T7, T8.......

The bay portion does not have the dark deep smooth look that the other fractal embayments have to the west. Instead, it appears bright (rough) and cut by thin dark channels. (My mind immediately jumps to images of frozen bays in Earth's arctic, with pack ice jostling around and making rough berg fields). Could this be a field of relatively rough organic scum all packed together? Or could it be a field of dried out bay and crusty stuff coating the drying shallows?
...
(I keep using the snow analogy for the organic shizzle-deposited areas - it seems to work, but it's important to remember that unlike snow, organic materials on Titan won't melt and might not even dissolve!)

I would guess the bright stuff is like the bright triangles in TA, which we interpreted as alluvial
fans - cobbles etc.
Nothing is very soluble (0.1 Molar, most much much less) in ethane/methane, at least per Raulin's
old paper. And basically nothing floats either (unless it is porous)

[Juramike]

Nprev, I like the idea of this being a collapsed pancake dome. That might explain the polygonal cracks.

Thinking way wild, perhaps the streams are choked with ice cobbles eroded from the cyrolava dome. These cobbles could have gas vesicles, --> cryopumice. These might appear radar-bright due to volume scattering from the porous materials (IIRC?), instead of being totally due to surface roughness.

[I have fond memories of floating pumice and having pumice races down Cache Creek near Crater Lake, OR.]

Normal rock has a density of ca. 6 g/mL and water's density is 1 g/mL. So in order to float, pumice has to be at least 80% air vesicles.

On Titan, normal ice has a density of ca. 1 g/mL (actually less) and hydrocarbon solvents have a density of ca. 0.6 g/mL (probably much less). So in order to float a cryopumice cobble, it would only need to have 40% air vesicles. (You need fewer pores to float an ice-rock on Titan).


So perhaps that bay further downstream is chock full of floating (or grounded) cryopumice cobbles?

It is very interesting that the steams downstream from Ganesa Macula are also full of bright material. As if something was eroded off, and deposited in a temporary lake or alluvial fan (maybe the alluvial fan was actually a bay?).

It is also interesting that the streams to the E of Menrva are also full of similar material with a similar morpology (bright streams ending in a bright alluvial near a dark lowland).

Maybe fresh ice-rock on Titan is porous in nature?

Maybe bright streams and abnormally bright bays are indicating fresh ice-rocks? Either from rapid erosion of cryovolcanics or from fresher impact scores?


All wild speculation of course, but it might be fun to check out RADAR images and follow bright streams and oddly bright alluvials back to their source to see if there is anything "fresh" in that location.

(And I still remember ngunn's speculation about the Huygens landing site "spooky dude" formation cobbles having been floated into position.)


-Mike

[ngunn]

Don't forget there is actual direct radar evidence of widespread porous surface materials in Xanadu, whereas even where they are only a minority fraction of the local erosion products that would still provide plenty of 'floaters'. Against this as I recall it was argued that porous materials do not form smooth pebbles but tend to crumble rather quickly into angular dust grains (which would no longer be buoyant). I don't know how to weigh the strength of that objection, but given that we are dealing with a completely different suite of materials from earthly pumice and completely unknown timescales I don't think it's a killer.

[Juramike]

I went back and looked at RADAR images to follow bright alluvials and bright streambeds back to their source. (And I found examples in Ta, T3, T7,... )

There is clear pattern of: "something" funky eroding (chaos, cryovolcano, crater rim, mountain) --> bright streambed --> bright alluvial --> bright embayment "trapped" (or left drying) in a darker basin.

I found examples in several RADAR swaths, in several regions of Titan, and in several drainages: North polar sea drainage, Mezzoramia drainage, Aaru drainage, Fensal drainage, and Aztlan drianage.


Here are RADAR images of selected diverse examples:

(Chaos areas eroding)


(Mountains or Crater rims eroding)




-Mike

[nprev]

Hmm. As usual, Mike, your customary impromptu PhD dissertation-level work both overwhelms and impresses us all... (as in "WOW!!!")

Very reasonable fit. One wonders if subsurface "emissions" of fluids (perhaps even of variable compositions) are arguably one of the most important influences on Titanian topography, outside of the equatorial dune fields...curiouser and curiouser. Think you may well have made an important find.