[X] My Assistant

[Juramike]

LPSC abstract provides an exciting preview:

http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1839.pdf

-Mike

[MarcF]

I didn't know that it was possible to change the viewing side during SAR scanning !!
Really great idea !! We will get a SAR view of Hotei and a nice resolution of the Huygens landing site.
I'm expecting some surprises.
Marc.

[ngunn]

LPSC abstract provides an exciting preview:

Indeed it does. I'm really hoping that some more of the highland valley networks and lowland 'flood moraines' in the Huygens images will be resolved. With the recent VIMS close-up data (also eagerly anticipated) this flyby should wrap up Cassini's landing site imaging campaign. I expect a comprehensive synthesis of these results will be undertaken at this point.

[rlorenz]

I didn't know that it was possible to change the viewing side during SAR scanning !!
Really great idea !!

It is nice to have the flexibility to do that, but you do lose a minute or two of imaging
during the turn (there is some data but degraded)

[nprev]

...you do lose a minute or two of imaging
during the turn (there is some data but degraded)

I figured that. Just out of curiosity, can the incident angle be changed sufficiently (and rapidly enough) to reimage the same area and hopefully produce a 3D composite, or is the relative velocity too great?

[Juramike]

I'm really hoping that the "spooky dude" formation gets resolved, and that other similar "spooky dude" formations are also observed in other channels.

I've got a pet theory that the "spooky dude" formation and most of the channel was emplaced gouged during a huge earlier flood event going from E to W, followed afterwords by smaller flood event(s) going from W to E. I think that reversible channels (not tidal) might be common on Titan.

(The spooky dudes parabolic shapes point the wrong way for them to have been emplaced during a W to E flood. Also, the tops are nice and bright in DISR, indicating they were high and dry during the last flood and didn't get the "organic paint" washed off.)

If this is correct, other nearby channels may show similar patterns and parabolic shapes going from E to W.

(I'm assuming the spooky dude formation is a RADAR-brighter cobble pile and will be slightly brighter when observed by RADAR compared to muddy ice sands. There were a few bright pixels in the T8 Swath that might've been a hint of the spooky dude formation.)

And I'm really, really, really hoping that the Cassini RADAR Team makes this swath available to the public really quickly, like they did for the South Polar Dec 20th Swath.

-Mike

[volcanopele]

Rev59 Looking Ahead article is now online: http://ciclops.org/view.php?id=4788

[Juramike]

From looking ahead: "The second half of the RADAR swath will also cover a part of far southeastern Adiri, seen by ISS as an interesting patchwork of bright and dark material."

I strongly suspect that Adiri is made of tectonic ridges going EW but with broader undulations that run N-S. When the two are combined, you get the cool-o checkerboard pattern seen in SE Adiri. (In the T8 RADAR Swath you can see that some sections of the long EW ridges have a thinner ice sand mantle. They have been partially buried by dune sands and darker smoother organic-ice muds.) The bright dark checkerboard pattern is also seen by ISS.

A different look angle might get some great 3D information that might confirm this.

-Mike

[rlorenz]

I figured that. Just out of curiosity, can the incident angle be changed sufficiently (and rapidly enough) to reimage the same area and hopefully produce a 3D composite, or is the relative velocity too great?

Not sure what you mean here by 3D composite- this sounds like spotlighting (dwelling on the same spot)
which beats down the speckle noise by getting more looks, but of course then you lose
areal coverage. We've done a little bit of spotlighting with HiSAR, but not near closest approach
as spotlighting then would sacrifice good coverage

[nprev]

Ralph, I was basically asking if Cassini can take a look at the same area during the same pass maybe a minute apart for stereo imaging. This spotlighting techniques sounds like what I meant, and understand that some coverage would have to be sacrificed; probably not worth doing often, since there's a lot of first-look radar mapping yet to be done.

[ugordan]

Excuse me for stealing the thread here a bit, but there's one thing puzzling me (English not being my first language):



I was always under the impression the construct Huygen's means belonging/related to something/someone named Huygen so in this case it would be wrong to spell it that way, rather Huygens' seems correct. I thought the former was a common spelling error with names ending with 's' in the english language, but I'm seeing it more and more lately and it makes me wonder - is that valid spelling?

[dvandorn]

Ugordan -- you're right, they're wrong.

-the other Doug

[nprev]

Good eye, Gordan; incorrect usage of the possessive apostrophe is extremely common among native English-speakers in the US.

BTW, if you never told anyone that English wasn't your first language, nobody would ever know; you are incredibly fluent!

[centsworth_II]

I think the correct form would be "Huygens" with no apostrophe
at all. "The Huygens landing site" is using Huygens as a name
for the site. If the phrase were "Cassini searches Titan for Huygens'
landing site," -- without "the" before Huygens -- then Huygens'
would be correct.

[ugordan]

That makes sense, centsworth_II. No apostrophe in this case sounds right.

Well, back to our regular program schedule now.

[dvandorn]

A very simple way to check if you're using the right construction is to replace the noun that naturally ends with an 's' with a noun that doesn't. In this case, let's replace it with the noun 'Viking' (another planetary lander), and the result:

"the Viking's landing site"

does read poorly. In this case, obviously, you don't need a possessive at all. It all hinges on the use of the definite article -- without the 'the,' you would use a possessive form.

-the other Doug

[rlorenz]

I think the correct form would be "Huygens" with no apostrophe
at all. "The Huygens landing site" is using Huygens as a name
for the site.

Yeah, I've seen (US) people who really should know better write
Huygen's more often than I'd expect.

Of course, you could dodge the issue and say 'Hubert Curien Memorial Station'

Or not.

[belleraphon1]

T41 mission description document now online.

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

Craig

[ngunn]

I notice the offending apostrophe has been removed. I wonder if you helped, Gordan?

All squeezed into the back seat now for tomorrow's flyby.

[edstrick]

Has any data been posted to the raw images brouser fur maybe 5 days?... I don't think the current LARGE batch of B-ring dark side monitoring images (I think that's what they are) have changed for that long.

[volcanopele]

Yeah, they are having issues again. Not sure why. We have gotten images since those B-ring images.

[Guest_Sunspot_*]

Yeah, they are having issues again. Not sure why. We have gotten images since those B-ring images.

Hmmm...it's been like it for 12 days now, are they aware it's not updating?

[Juramike]

It looks like some raw images from the Titan encounters might be up, but I'm not able to see any of the images or read the files.

Anyone else having this problem?

[Doc]

It looks like some raw images from the Titan encounters might be up, but I'm not able to see any of the images or read the files.

Anyone else having this problem?

I too am having a problem. The images dont appear at all.
What the heck is going on?!

[Juramike]

New images are up!!!

Here's a nice image of the Ciclops-dude of Belet: http://saturn.jpl.nasa.gov/multimedia/imag...8/N00103240.jpg

(Adiri to the East)

-Mike

Some of the closer images seem a bit "fuzzier" than normal, maybe due to the filter set used?

[Stu]

Lots of clouds over Titan..?



Original image found here...

[ugordan]

I'm only seeing one obvious cloud, the streaky one up in the north. The brighter region south of the equator is I believe a terrain feature (possibly something seasonal), see this thread for example. Take note that the obvious clouds (the south pole one and a hint of a north polar cloud) have a different color than the brighter terrain in both types of multispectral composites.

[Matt]

A new radar image appeared about an hour ago, showing radar bright channels on Hotei Arcus, but now it's vanished!

Hopefully it will be back again soon.

[volcanopele]

Yeah, it is not up at the moment, but to give you an idea:

http://photojournal.jpl.nasa.gov/catalog/PIA02568

Ducks and runs...

[ugordan]

Yeah, it is not up at the moment, but to give you an idea:

LOL at the coincidence. That imagery was taken on Feb 22, 2000, exactly 8 years before the "missing" RADAR image.

Time flies, doesn't it?

[Webscientist]

I've also seen the latest radar image of Hotei Arcus with these radar bright channels.
When I take a look at Hotei Arcus in VIMS images, I have the impression it is the outcome of a meteoritic impact. I assume that the bright staff has been ejected to the east. I see a steep slope on the west part of the assumed irregular crater and a more progressive slope to the east probably because the meteor came from the west or north west.
I propose three hypothesis for the nature of the bright channels or grooves:
first: the pseudo channels are a consequence of methane (...) rain.
Second: the pseudo channels have been carved by some materials resulting from the impact.
Third: the pseudo channels are pseudo lava tubes, in other words channels througout which a liquid like carbon dioxide or liquid water have run.

Of course, I don't see in a crystal ball. So It is only a point of view. It could also be a cryovolcanic phenomenon...

[Matt]

bright channels seemed to flow away from bright rugged terrain in the south down to darker, lower terrain, but it I thought it looked as though their might have been two different types of deposit; younger, darker deposits overlaying older, slightly brighter (rougher?) deposits. I only saw the image briefly and at it's lowest resolution though....so I may have completely misinterpretad it.

[Matt]

I think I'd go for a combination of 1 and 2 regarding your propositions

But would really like to see the image again at higher res

[titanicrivers]

Has anyone seen the T41 SAR hi res image posted in a public forum. It was mentioned in abstracts and presentations in Feb and March conferences but I've yet to see it except on global map in one of Emily's Planetary Society blogs from 2 weeks ago. I was curious about the consensus on what Hotei Arcus proved to be! (that 'smile' reminded me of an old impact basin partially filled in or eroded away.

[ngunn]

A lot of people (including me) are very keen to see this swath in particular. I think the release of SAR images is having to wait for a revised assessment of Titan's rotation state to establish a more secure system of geographical coordinates. I don't know if this affects the processing of the images themselves or just delays their publication.

[titanicrivers]

I wonder if the SAR crew are awaiting the T-43 flyby data so as to make a stereo composite of Hotei Arcus to enhance its identity via a topography mapping. Would make a nice short paper.

[titanicrivers]

Came accross this poster abstract from a recent Planetary Science meeting:

P23A-04
Titan's Surface Geology from the Cassini RADAR

* Lopes, R M (rosaly.m.lopes@jpl.nasa.gov), Jet Propulsion Laboratory, Caltech, Pasadena, CA 91109, United States et. al.

With respect to Hotei Arcus:
"The T41 flyby, which took place in February 2008, obtained SAR coverage of the Hotei Arcus region, which has been suggested as cryovolcanic and possibly currently active [Nelson et al., submitted to Icarus]. SAR images obtained to date show that cryovolcanism is not ubiquitous on Titan, and that some features interpreted as cryovolcanic, such as Ganesa Macula appear to be old and modified by other processes. The flows in the Hotei Arcus region appear well-preserved and are younger than surrounding terrains, implying that cryovolcanic activity may have occurred relatively recently. Mapping of geological units from SAR data is revealing the distribution and relative ages of geological materials which, in turn, helps us to understand the evolution of Titan's surface."

Has anyone seen the images that would have accompanied this presentation?!

Other interesting abstracts from that meeting (some on Titan) are at www.esa.int/esaMI/Cassini-Huygens/SEMLMXLVGJE

[Juramike]

Good catch, titanicrivers!

[A quick Google search turns up that P23-A04 is also a portion of the gene sequence of the malaria genome. That link might come in handy someday.]

Here is the link to the Titan abstract.

A few other quotes plucked from the abstract (emphasis in bold mine):

"Channels and drainage features appear common at all latitudes, indicating that erosion by liquids has been a major modification process."

"cryovolcanism is not ubiquitous on Titan"

Hopefully the Nelson et al. paper cruises through peer review. Definitely something to look forward to...
(Maybe they'll release the T41 RADAR Swath soon after?)

-Mike

[Ha! Looks like titanicrivers beat me to clipping out the abstract! Post modified so as to not be redundant with titanicrivers' post above]

[titanicrivers]

Good catch, titanicrivers!
[Ha! Looks like titanicrivers beat me to clipping out the abstract! Post modified so as to not be redundant with titanicrivers' post above]

Lol ! Sometimes these little Eureka-moments can make one's day! Can imagine how exciting the raw data is to the primary investigators when they receive it from Cassini!

[remcook]

I think the Nelson et al. paper refers to analysis of VIMS cubes, showing apparent changes of brightness at hotei arcus. He seems to be promoting this idea for quite some time already. see:
http://adsabs.harvard.edu/abs/2007AGUFM.P22B..03N
http://adsabs.harvard.edu/abs/2007LPI....38.2158N
http://adsabs.harvard.edu/abs/2006AGUFM.P12A..06N
http://adsabs.harvard.edu/abs/2006DPS....38.5209N
http://adsabs.harvard.edu/abs/2006epsc.conf..404N
http://adsabs.harvard.edu/abs/2006cosp...36.2128N
http://adsabs.harvard.edu/abs/2005DPS....37.4612N
Must be hard to get through the review process.

I assume the reason for the late release (and quick pulling on the website) of the SAR data of Hotei Arcus is that they are trying to get it in Science/Nature.

[titanicrivers]

[quote name='ngunn' date='Apr 25 2008, 01:56 AM' post='112814']
A lot of people (including me) are very keen to see this swath in particular.

R. Lopes and colleagues have presented their findings at DPS 2008 concerning Hotei Arcus. An enhanced T41 radar image of Hotei Arcus appears below. It is worth logging into her slide presentation given earlier today. Link to all the talks here: http://dps08.astro.cornell.edu/AAS_WebcastSchedule_2008.html .Her presentation is in: Session 34: Titan: Subsurface: http://cornellmediasite.cit.cornell.edu/me...c7-17e07b541bdb
Her presentation starts at slide 75. To get there quickly click on "text slide list" and scroll down to slide 75 and click on "slide 75 00:23:42"

[ngunn]

That was interesting indeed, but I note that the Huygens landing site is still under wraps.

[ngunn]

Thanks to Bjorn for this:
http://www.unmannedspaceflight.com/index.p...ic=5697&hl=

Does this mean we now have the SAR covering the Huygens landing site?

[peter59]

Huygens Landing Site and Hotei Arcus.

Enjoy !

[volcanopele]

Looks like that is only the Huygens landing site area, don't see Hotei Arcus in there.

Juramike's favorite sliced carrot is at right in that view.

[Juramike]

...and the part that would show whether or not there was a central rise at the centroid of the sliced carrot feature is...just....out..of..view.....

arrrgh!

Any chance this will arrive on VP's RADAR Swath page soon?

[volcanopele]

Alright, alright, I'm on it

[volcanopele]

I've added the three swaths from T41 to my RADAR swath page, as well as the T30 swath that finally showed up on the PDS a couple of months ago:

http://pirlwww.lpl.arizona.edu/~perry/RADAR/

[Juramike]

Wow! Thank you!

That T41 Hotei Arcus portion is just totally enigmatic. I'm having a hard time seeing exactly how it aligns with the ISS images.

[ngunn]

A SAR feast indeed! Long awaited and much appreciated. As usual I cannot trust my objectivity when peering at these images, especially the Huygens area, so I look forward to someone doing a proper job of correlation with the Huygens DISR panorama. I think the 'spooky dude' can be discerned.

[volcanopele]

Here are some gifs to help with feature correlation:

Attached thumbnail(s)

 

[Juramike]

Thanks for that, VP!

I'd really blown my attempted lineup of Hotei Arcus. You have set me on the correct path to illumination....

-Mike

[titanicrivers]

A SAR feast indeed! Long awaited and much appreciated. As usual I cannot trust my objectivity when peering at these images, especially the Huygens area, so I look forward to someone doing a proper job of correlation with the Huygens DISR panorama. I think the 'spooky dude' can be discerned.

Look at the center portion of T41 for those 2 dark dunes (arrows) and you can match 'em up. (see Fig below, HLS= Huygens Landing Site (red cross))

[ngunn]

Thanks for that useful comparison TR. I had no trouble locating more or less the right spot but what I didn't have was the exact scale and orientation for a precise comparison. Unfortunately your red cross obscures a lot of the features I was looking for in the new SAR image, namely the bright banks or ridges located within the dark area between the two bright river-dissected 'islands'. The question of whether these are resolvable by the RADAR is vital to recognising if the spot where Huygens landed represents a common type of terrain or an unusual one. The background question of greatest interest to me here is whether the banks/ridges (outlining the Huygens 'spooky dudes') are entirely mobile drift features or solid topography, albeit modified and partly mantled by drift.

[Juramike]

To my eyes, it looks like the T8 RADAR Swath has slightly better resolution in the Huygens Channel area.

There might be a few bright pixels in the T8 image that correspond to the "spooky dude" formation, but it's hard to discern from random noise.
A slightly better candidate would be the pockety area to the SE (downchannel towards Ching-Tu) that might have a few more brighter pixels in the RADAR images. Those more brightish pixels seem to be present in both T41 and T8 RADAR swaths, so I think they might be real. This is just slightly beyond the red cross down and to the left in titanicrivers' image.

[I'm having a rough time lining up exactly the T41 Swath with the PIA08399 ISS basemap. I can get the Huygens Island and the Sliced Carrot features to line up nicely, but it's off a few 10s of km down near the islands in Ching-Tu basin at the S end of the Swath. I'm suspect it is due to trying to project the RADAR swath on the flat projected image that is causing the distortion (or is this due to the funky drift of Titan amplified by the map projection towards higher latitudes??). I'll be trying to play around with horizontal and vertical skews tonight until I'm satisfied it's "good enough".]

-Mike

[ngunn]

To my eyes, it looks like the T8 RADAR Swath has slightly better resolution in the Huygens Channel area.

Surprising, since T41 is much the narrower of the two here.

I was looking at the version by peter59 in post 44 of this thread. It's there I think I'm possibly seeing certain recognisable features within the Huygens Channel (good name). I agree that Jason's version is very speckly in this area, and I can't make out anything. It would be interesting to know why the two versions (of T41) look so different. I've noticed before that I can always see a lot more on the SAR images posted by peter59. They're a lot brighter for one thing.

Anyhow I look forward to seeing what you do with this Mike, and I hope others have a go too. Maybe we'll even get some SAR 3D from T8 and T41.

(Then there's still the VIMS to come: whether a direct hit or not that will be fascinating.)

[Juramike]

I think I got it lined up...

And no, the Spooky Dude formation is most definitely not visible. In fact, after careful lineup, it correlates best with the darkest pixels in mid-channel slightly towards the northern island. Actually, the South Island extends halfway into the RADAR-darker visible channel. The RADAR bright terrain most likely correlates only to the steepest terrain of the islands.

[For instance, on the island just N of the Huygens Channel, the brightest RADAR signature is for the two highlands on either side of the dendritic (normal looking) channel. The portion of the island with the dark stubby slough-like channel is not discernible above backround in the RADAR image].

I'll try to post pretty images over the next few days.

-Mike

[titanicrivers]

[quote name='ngunn' date='Jan 7 2009, 02:21 PM' post='133831']
Surprising, since T41 is much the narrower of the two here.

"I was looking at the version by peter59 in post 44 of this thread. It's there I think I'm possibly seeing certain recognisable features within the Huygens Channel (good name). I agree that Jason's version is very speckly in this area, and I can't make out anything. It would be interesting to know why the two versions (of T41) look so different. I've noticed before that I can always see a lot more on the SAR images posted by peter59. They're a lot brighter for one thing."

Good points ngunn and Mike!! I went back and reviewed all the posted SAR images and really couldn't identify the ridges in the Huygens Channel; of course the smaller fluvial and spring-like channels on the 'islands' were not discernable.
One of the best images (see T41 post #1) identifying structures in T8 and DISR was the LPSC abstract of Lorentz et. al and the detail you mention was not identified either. As you mentioned T41 was to be of higher resolution and at a different 'look' angle and so promising to reveal more of the DISR ground-truth details.

In their paper on fluvial channels the rlorentz et al conclude: "It is, however, striking that the fluvial channels observed by Huygens were on a scale far too small for the Cassini orbiter radar to observe, and the low-resolution (4700 m)radar images over the landing site so far did not identify larger-scale channels (Lunine et al., in press). Thus one might worry about the extent to which Titans surface is worked by smaller-scale fluvial features invisible to the radar and not connected to larger, radar-detectable channels."

I get the feeling some discoveries will have to wait for a Titan Polar Orbiter or atmospheric balloon mission!

[ngunn]

4700 m resolution for the SAR cannot be right. As Mike's animation on the Huygens news thread (nice work!) shows, if the 'spooky dudes' aren't visible to SAR that's certainly not because they're too small. We know that at least some of the ridges have elevations of many tens of metres and extend for several kilometres. We also know from the Huygens surface image that at least one area is rough on RADAR wavelengths since it is littered with pebbles a few centimetres in diameter. There must be another reason for this particular aspect of their spookiness. As a first wild suggestion I'd say that the pebble banks or ridges (however they got there) must be composed of RADAR-transparent organic materials very different from whatever makes up the bright 'islands'.

One implication of this is that similar significant and sizeable SAR-invisible features could exist all over the place on Titan.

VIMS could be Cassini's best hope here.

[titanicrivers]

[quote name='ngunn' date='Jan 8 2009, 03:15 AM' post='133852']
4700 m resolution for the SAR cannot be right.

You are correct! In the body of the article on river erosion (R.D. Lorenz et al. / Planetary and Space Science 56 (2008) 1132-1144) is the statement "The Huygens landing site was observed by the Cassini radar on T8 in October 2005 (Lunine et al., submitted for publication) but no fluvial channels could be observed in that data, which was acquired near the longrange end of the swath and had a resolution a little poorer than 1 km. (my emphasis).

The original quote above should have been "... > 700m resolution" and not 4700m!