Printable Version of Topic

Click here to view this topic in its original format

Unmanned Spaceflight.com _ Titan _ Lakes in the limelight

Posted by: ngunn Sep 13 2013, 02:20 PM

A fantastic collection of new images of the northern lakes has just arrived: http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=298704

Posted by: titanicrivers Sep 13 2013, 03:12 PM

Very cool raw images indeed !!


Posted by: Phil Stooke Sep 13 2013, 03:13 PM

Wow, they are great. This is one with a bit of a stretch and cleanup.

Phil


Posted by: volcanopele Sep 13 2013, 04:10 PM

Wow, looks like I'll be busy for a while...

Still sorting through the images myself.... This looks like a great image of Sparrow Lacus

http://saturn.jpl.nasa.gov/photos/raw/rawimagedetails/index.cfm?imageID=298793

Posted by: Ian R Sep 13 2013, 09:46 PM

Three-frame WAC mosaic of Titan's northern wetlands, with a *tentative* identification of PUNGA MARE labelled as 'PM'.


Posted by: stevesliva Sep 13 2013, 11:04 PM

Is any high-contrast spot safely assumed to be a lake?

Posted by: Ian R Sep 14 2013, 11:31 AM

At this latitude, I think that's a fairly safe assumption.

Posted by: ngunn Sep 14 2013, 11:38 AM

Recalling the south polar views from a few years back there is also the possibility of temporary dark patches resulting from recent rain.

(BTW does anybody know if recent lake imaging includes any shots through polarising filters? My sporadic searches have not turned up any.)

Posted by: Ian R Sep 14 2013, 02:59 PM

The same region of Titan's north pole, as seen by radar (cropped from PIA10008):




Posted by: Ian R Sep 14 2013, 03:02 PM

Blink GIF version:


Posted by: Ian R Sep 14 2013, 03:35 PM

Labelled version:

http://postimg.org/image/3uvjfogdz/

Posted by: ngunn Sep 14 2013, 08:43 PM

Nice mosaic and great overlay. There are some interesting differencences from the SAR view.

Here is an image from a few days earlier that I like because it shows almost the whole of Titan's northern lake province now in daylight. (It's one of many that are ripe for stacking and other clever stuff.) http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS80/N00216700.jpg

Posted by: Juramike Sep 14 2013, 09:30 PM

QUOTE (Ian R @ Sep 14 2013, 07:31 AM) *
At this latitude, I think that's a fairly safe assumption.


There are no safe assumptions on Titan.

Posted by: antipode Sep 14 2013, 11:02 PM

QUOTE (Juramike @ Sep 15 2013, 08:00 AM) *
There are no safe assumptions on Titan.


Looks like its been raining up there! ph34r.gif

P

Posted by: Ian R Sep 15 2013, 02:24 AM

QUOTE (Juramike @ Sep 14 2013, 10:30 PM) *
There are no safe assumptions on Titan.


True, true: but I still think it's fairly safe to say the dark splodges are more likely to be fluid-related than anything else.

Posted by: titanicrivers Sep 24 2013, 07:46 AM

"Here is an image from a few days earlier that I like because it shows almost the whole of Titan's northern lake province now in daylight. (It's one of many that are ripe for stacking and other clever stuff.)"

Agree the earlier views of the N polar lakes are striking. The September 6th images stand in stark contrast to those of Sept 2009 when plenty of tropospheric clouds appeared over the N polar lakes and seas (figure on left). The apparent lack of clouds raise questions as to 1) whether the clouds are seasonal-atmospheric phenomena and not much influenced by the lakes presence or 2) whether the lake/sea composition and minimal seasonal winds at this time are less conducive for cloud formation.
The color composite images and the upper haze layers (seen in the UV3 filter) are also awesome (figure on the right).


Posted by: ngunn Sep 26 2013, 06:11 PM

One late arrival - some smallish lakes from fairly close in. Is that MacKay lacus at the bottom left?
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS80/N00217222.jpg

Posted by: ngunn Oct 15 2013, 09:55 PM

Another family portrait of Titan's great lakes, clockwise from top: Kraken, Jingpo, Punga, Ligeia.
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS80/N00217414.jpg

Posted by: Ian R Oct 16 2013, 08:06 PM


Posted by: ngunn Oct 16 2013, 09:04 PM

Beautiful! I was really hoping someone would do that, so my hearty thanks. smile.gif
There's one area in these new views that I'm finding hard to reconcile with the earlier ISS views of the lakes. It's the area on the eastern side of Kraken Mare that in the first images resembled the foot of Italy. Looking at it now Italy appears to have curled up its toe! Here's the older view: http://upload.wikimedia.org/wikipedia/commons/5/50/Kraken_mare.jpg

Posted by: titanicrivers Oct 23 2013, 02:04 AM

I've added a Sept 2013 image (bottom of composite figure below) of Kraken. The "toe of Italy" is about the same stage of 'falling off' as best I can tell and there hasn't been major changes from 2007. Perhaps with the ground surrounding the lake and seas saturated with methane and/or ethane http://www.newscientist.com/article/dn24430-astrophile-soggy-bogs-swallow-craters-on-titan.html big changes are not expected.


Posted by: ngunn Oct 23 2013, 12:48 PM

My clumsy atempt to highlight what I was referring to on a crop from Ian R's mosaic. 'Toe' is the upper oval. Lower oval is the dark area I don't see on the earlier images.

EDIT: still trying to attach . . aah, there we go:

 

Posted by: volcanopele Oct 23 2013, 07:25 PM

I can finally show off our versions of these mosaics:

T92 MONITORNA001:
http://www.ciclops.org/view/7730/Dark-Lakes-on-a-Bright-Landscape

T93 MONITORNA001:
http://www.ciclops.org/view/7731/Titans-North-The-Big-Picture

T94 REGMAP001:
http://www.ciclops.org/view/7732/Birds-Eye-View-of-the-Land-of-Lakes

T94 VIMS HIRES:
http://www.ciclops.org/view/7733/Titans-Northern-Lakes-Salt-Flats

Posted by: ngunn Oct 23 2013, 09:14 PM

What a bountiful harvest of wonderful views!!! There is unprecedented detail (I think) in the ISS products and the spectacular VIMS release is particularly welcome. We had evidence of a light fringe around Kraken Mare before but now we see the full extent of these possible evaporite deposits. I'm a bit surprised that the greenish background on the VIMS mosaic is described as water ice. I thought exposed water ice was rather rare on Titan.

Posted by: elakdawalla Oct 23 2013, 09:22 PM

I think I had a conversation with somebody about that at DPS -- that there's a new calibration of VIMS data that has changed the apparent relative brightness of the surface in two windows that suddenly make water ice a possibility for that surface. I think. I better go check that with somebody. Is Jason Barnes still hanging around here?

Posted by: ngunn Oct 23 2013, 09:34 PM

Such a reinterpretation would make sense. I think the Huygens team has always maintained that the pebbles on the surface are probably water ice. It would be good to know, one way or the other.

Posted by: Ian R Oct 23 2013, 09:36 PM

Fantastic work Jason! ohmy.gif

Posted by: Jason W Barnes Oct 23 2013, 10:00 PM

QUOTE (elakdawalla @ Oct 23 2013, 02:22 PM) *
I think I had a conversation with somebody about that at DPS -- that there's a new calibration of VIMS data that has changed the apparent relative brightness of the surface in two windows that suddenly make water ice a possibility for that surface. I think. I better go check that with somebody. Is Jason Barnes still hanging around here?

I've been lurking recently, but I show up every once in a while wink.gif The greenish stuff is probably more icy than the evaporites, for sure, but isn't pure water ice, even with the 2.7/2.8 micron correction that I talked about at DPS. But it's got SOME ice, while the evaporites have none. Note that the press release was simplified from what I would have written; I don't get to have them be rigorous enough for this crowd always wink.gif

- VIMS Jason

Posted by: remcook Oct 24 2013, 06:21 PM

There was an interesting talk by Pascal Rannou at EPSC ( http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-459.pdf - although the abstract doesn't mention results yet), showing a very nice fit to the DISR data with a combination of water ice and fractal haze particles. Apparently it shows a water ice feature at 1.5 micron.

Posted by: Jason W Barnes Oct 24 2013, 07:45 PM

QUOTE (Jason W Barnes @ Oct 23 2013, 03:00 PM) *
The greenish stuff is probably more icy than the evaporites, for sure, but isn't pure water ice, even with the 2.7/2.8 micron correction that I talked about at DPS.

Speaking of which, the paper associated with that talk is just now out in ApJ, http://oom9.barnesos.net/publications/papers/2013.11.ApJ.Barnes.SpecularTransmission.pdf.

- VIMS Jason

Posted by: ngunn Oct 24 2013, 09:20 PM

A joy to read; thanks very much as ever for making your paper availalable to all. What it says about the presence of water ice on the surface of Titan is a tiny part of a paper that has so much more in it, but it's the sort of nugget that is much appreciated here.

Posted by: rlorenz Oct 26 2013, 04:33 AM

QUOTE (remcook @ Oct 24 2013, 02:21 PM) *
There was an interesting talk by Pascal Rannou at EPSC ..... showing a very nice fit to the DISR data with a combination of water ice and fractal haze particles. Apparently it shows a water ice feature at 1.5 micron.


Awesome. 20 years ago we were grappling with disk-integrated groundbased spectroscopy, and the best fit people could come up with was 'dirty ice'. And now, after much debate on Huygens/DISR and Cassini/VIMS, we discover.....dirty ice. This is getting as bad as water on Mars.....

Posted by: stevesliva Oct 26 2013, 10:04 PM

QUOTE (rlorenz @ Oct 26 2013, 12:33 AM) *
Awesome. 20 years ago we were grappling with disk-integrated groundbased spectroscopy, and the best fit people could come up with was 'dirty ice'. And now, after much debate on Huygens/DISR and Cassini/VIMS, we discover.....dirty ice. This is getting as bad as water on Mars.....


For any poorly constrained yet hugely significant question in planetary science, there will be an endless series of releases answering various better-constrained versions of that question.

See also, Voyager, exiting solar system. Or earthlike planet, discovered.

Posted by: Explorer1 Oct 26 2013, 10:48 PM

There was controversy about what material Huygens pebbles were made of? Wasn't water ice the obvious explanation right from the start? Obviously confirmation is important news but what other material could they have been?
I remember reading it in the thread in this very sub-forum as the images came down.
Good times...

Posted by: ngunn Oct 27 2013, 10:30 AM

QUOTE (Explorer1 @ Oct 26 2013, 11:48 PM) *
what other material could they have been?


Take your pick from a wide range of waxy or soapy organics (evaporites?). We were staring at them but we just didn't know - and truth to tell we still don't, even if water ice now seems increasingly likely.

Posted by: Juramike Oct 31 2013, 04:43 AM

The effective dielectric constant data over most of Titan, including the Huygens landing site, is not consistent with water ice. (Janssen, 2010)
Spectral measurements only look at the top few microns of paint.
RADAR probes deeper.

+Mike

Posted by: ngunn Aug 9 2014, 09:57 PM

I've been busy with house and family and missed this when it came out. It's a particularly clear view of Titan's lake district:
http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS84/N00227079.jpg

Apart from enjoying the whole picture I notice there is a bright streak across the middle of Ligeia Mare. Is it a patch of cloud, or something to do with the 'magic island' recently reported off one of Ligeia's headlands?

Posted by: volcanopele Aug 10 2014, 01:04 AM

Those are clouds.

Posted by: elakdawalla Aug 10 2014, 02:42 AM

Forgive me if I'm out of touch, but: Jason, haven't you been looking for clouds for, like, a long time? Is this a big deal?

Posted by: belleraphon1 Aug 12 2014, 07:38 PM

Cassini press release

Cassini Tracks Clouds Developing Over a Titan Sea
http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20140812/

CICLOPS site
http://ciclops.org/view/7929/Clouds-Over-Ligeia-Mare-on-Titan?js=1



Posted by: volcanopele Aug 12 2014, 09:01 PM

Hmm, well, I guess I can talk about this now. Yes, we have been looking for clouds for a while and not seeing them. And yes this is kind of a big deal.

Posted by: antipode Aug 13 2014, 09:25 AM

Is this a 'lake effect'? Is there much of a difference between the liquid and the overlying atmosphere?

P

Posted by: MahFL Aug 13 2014, 12:23 PM

For a weather nut like me, that is awesome smile.gif.

Posted by: titanicrivers Aug 17 2014, 03:27 PM

Yes, awesome observations and imaging! From Rev 207 http://www.ciclops.org/view/7921/Rev207 two CB3 images N00227321 and N00227310 taken on August 13th appear to show clouds in motion over Ligeia Mare and Muggel Lacus. (although spacecraft motion causes whole image shift and my less than ideal image processing may have me fooled!)


Posted by: ngunn Aug 20 2014, 09:01 PM

Well we've seen the first clouds for a while and measured their speed, now its time to hunt for the 'magic island', lake altimetry and depth sounding.
http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCIQFjAA&url=http%3A%2F%2Fsaturn.jpl.nasa.gov%2Fmission%2Fflybys%2Ftitan20140821%2F&ei=jAv1U-umFMyh7AbXyIFA&usg=AFQjCNF-m66kzFwGIQQfUmBQIlGBq2EYXQ&bvm=bv.73231344,d.ZGU

Will the data from this flyby establish the relative surface altitudes of Ligeia nd Kraken? I'm not sure what is meant by Kraken Mare's estuary. Does that term refer to the channels that appear to link it with Ligeia or the ones around Mayda Insula? I note that the first convection clouds appeared over Ligeia, not Kraken. This would be consistent with Ligeia being relatively methane-rich and draining into Kraken; the latter acting as the less volatile ethane sump.

Posted by: titanicrivers Aug 21 2014, 01:54 AM

I presume this is the estuary (E) connecting Ligeia mare (L) and Kraken mare (K).


Posted by: Juramike Aug 21 2014, 01:29 PM

Yup.

See: Sotin et al., Icarus 221 (2012) 768–786. "Observations of Titan’s Northern lakes at 5[microns]: Implications for the organic cycle and geology".
doi: 0.1016/j.icarus.2012.08.017.

Freely available here: http://www.barnesos.net/publications/papers/2012.11.Icarus.Sotin.Northern.Lakes.pdf
(Thanks to Jason Barnes for making this available on his webpage.)

Posted by: ngunn Aug 21 2014, 10:07 PM

Thanks for that confirmation of what is meant by 'the estuary'. Actually there seem to be quite a lot of estuaries draining into Kraken Mare, mostly at its northern end from what we've seen so far. The paper you refer to explicitly leaves as a significant open question the relative levels of Kraken and Ligeia, hence my interest in whether the current flyby science activities aim to address this.

Posted by: brellis Aug 22 2014, 09:23 PM

When Cassini first arrived at Saturn, the release of Huygens was delayed (to get a better angle for comm relay, IIRC). I wondered why not delay it for many orbits so a landing site could be chosen based on the better info being obtained from numerous Titan flybys. Prudence favored releasing the lander as soon as possible.

A question for our Titan experts: if Cassini were still carrying Huygens today, where (and when) on Titan would you want to have it land?

Posted by: ngunn Aug 22 2014, 09:42 PM

QUOTE (brellis @ Aug 22 2014, 10:23 PM) *
if Cassini were still carrying Huygens today, where (and when) on Titan would you want to have it land?


(No expert, but I do have opinions . smile.gif )
I'm really glad nobody had the chance to choose the site. It landed with exceptional good fortune in a very information-rich location which would never in a month of Sundays have been selected by cautious planners. But yes: now we know what we know, and what we know is we badly need a robotic chemist in one of the lakes. Huygens was designed to cope with a lake landing but it wouldn't have done much chemistry.

Posted by: ngunn Aug 23 2014, 06:59 AM

At first sight there appears to be a line of cloud in much the same place as before in this new image (on the far right just above Ligeia Lacus): http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS85/N00228346.jpg

Posted by: Ian R Aug 23 2014, 04:03 PM

Yep, there seems to be a cloud right between Muggel and Ligeia, alright.


Posted by: rlorenz Sep 1 2014, 12:36 AM

QUOTE (ngunn @ Aug 22 2014, 04:42 PM) *
I'm really glad nobody had the chance to choose the site. It landed with exceptional good fortune in a very information-rich location which would never in a month of Sundays have been selected by cautious planners..... Huygens was designed to cope with a lake landing but it wouldn't have done much chemistry.


Yes, and no. The entry point was determined by a number of engineering factors (entry angle tolerable by heat shield defines a circle, given the delivery asymptote). Solar illumination for the descent spectral measurements, and communications geometry (including having the line of sight mostly east-west for doppler wind measurements) were also constraints. These determined a small entry region around 145W 20N.

This site was targeted by VIMS on the first Titan flyby (and hence had the first Nature paper written about it). The feature that happened to be at that spot, now named Tortola Facula, although I nicknamed it the 'cat poo', was possibly overinterpreted as a cryovolcanic construct - I think observations since do not lend much support to that interpretation.

When the Huygens mission had to be redesigned following the receiver design flaw discovered on the Earth flyby in 1999, the new delivery scenario actually relieved some of the communications constraints on the delivery point, and we actually had a choice of 2 sites (and now, circa 2002 IIRC, crude maps to think about) at 190W and 10 North or South. We actually discussed it and South won, because it was the border between near-IR (940nm) bright and dark stuff. 940nm data, even at this point, don't really discriminate photometrically between dunes and seas, and no-one really expected the former! (By this time the observation planning had moved to later in the tour, and the VIMS targeting of the old landing site remained unchanged..)

Anyway, had the probe landed in a liquid, it might well have capsized depending on the wind (the payload was indeed designed mostly with a liquid landing in mind, but the probe itself had no design requirements for any landing). The GCMS inlet was heated with the intent of volatilizing surface material, which indeed occurred in the damp regolith we landed in. So it might have been quite interesting chemistry-wise.

Obviously, we might well aim for the seas now, although they might in fact be of quite different composition. Ligeia looks to be rather methane-rich ('fresh') while Kraken may be more solute-rich (analogous to the Baltic and the North Sea, or the Black Sea and the Mediterranean) - see http://www.lpl.arizona.edu/~rlorenz/flushing_preprint.pdf
A sonar would probably work better in Ligeia, but from a chemistry standppoint Kraken might be the preferred choice. To understand the hydrological cycle you'd probably want a lander for each, or a vehicle that could somehow sample both......

Anyway, I take your point. If you want to survive a landing, a gullied streambed would likely not be the best choice. If we knew the surface, would we have aimed for the dunefields (as we did in the 2007 APL Titan Explorer Flagship Mission Study, before the seas had been mapped) ? Or the midlatitude blandlands? If we knew the seas were there, would we have targeted them - perhaps not - remember they were in winter darkness in 2005 !

Indeed where we ended up was information-rich - it certainly showed instantly that Titan was a hydrologically-shaped world.

Posted by: ngunn Sep 1 2014, 11:54 AM

QUOTE (rlorenz @ Sep 1 2014, 01:36 AM) *
from a chemistry standppoint Kraken might be the preferred choice.


Perhaps specifically the southern basin of Kraken given the drainage scheme you postulate there? I note that it lies partly outside Titan's arctic circle so would receive at least some sunlight even in midwinter. I don't know if the same can be said for the possibility of direct-to-earth communications

Posted by: rlorenz Sep 1 2014, 01:40 PM

QUOTE (ngunn @ Sep 1 2014, 07:54 AM) *
Perhaps specifically the southern basin of Kraken given the drainage scheme you postulate there? I note that it lies partly outside Titan's arctic circle so would receive at least some sunlight even in midwinter. I don't know if the same can be said for the possibility of direct-to-earth communications


There it comes down to a 'how little data will you accept and how much risk of terrain obstruction' question. The usual story of contemporary planetary exploration - anything is possible, but how do you prove that there is no way, at all, ever, that it could possibly go wrong...

Arguably at the extreme south of Kraken (ditto at Ontario) the material is more likely to be muddy/viscous, which makes landing dynamics and material sampling harder to test/verify (again, chances are everything would be fine, just costs a lot to demonstrate..)

Posted by: titanicrivers Sep 4 2014, 02:44 AM

QUOTE (rlorenz @ Aug 31 2014, 06:36 PM) *
Obviously, we might well aim for the seas now, although they might in fact be of quite different composition.

… and this paper in Icarus http://www.jpl.nasa.gov/news/news.php?release=2014-294 might help explain sea composition differences if some seas are much older and therefore alkanofers and clathrate composition changes and interactions can influence extant sea composition.

Posted by: titanicrivers Sep 5 2014, 03:58 PM

Below is NAC view (N00228357 from 256K km on 8-21-2014 CL1 CB3 filter) from the T104 flyby covering the Kraken (K) – Ligeia (L) estuary. The cloudy region (Cl) between Muggel (M) and Ligeia is well shown, the estuary (arrow) just barely visible. The image shows the ‘Looking Ahead’ ISS map (with a hint of radar) first and then the enhanced-cropped view of N00228357 fills in the right half of the scene.


Posted by: rlorenz Sep 16 2014, 01:19 AM

QUOTE (titanicrivers @ Sep 5 2014, 10:58 AM) *
Below is NAC view (N00228357 from 256K km on 8-21-2014 CL1 CB3 filter) from the T104 flyby covering the Kraken (K) – Ligeia (L) estuary.


The connection between Ligeia and Kraken may involve several parallel channels (hence I referred to it in my flushing paper as the Ligeia-Kraken Labyrinth, LKL)

I'd say the Kraken inlet next one up from the labyrinth might be a better place for the label 'estuary'. (It was in this inlet that a radiometric change between T25 and T28 was observed, maybe suspended sediment?)

Posted by: ngunn Sep 30 2014, 05:08 PM

The 'Magic Island' returns: http://photojournal.jpl.nasa.gov/catalog/PIA18430

Posted by: marsbug Sep 30 2014, 09:41 PM

I love mysteries, especially when their circumstances mandate that even the most mundane explanation will be extraordinary.....

Posted by: TheAnt Sep 30 2014, 11:12 PM

QUOTE (marsbug @ Sep 30 2014, 11:41 PM) *
I love mysteries, especially when their circumstances mandate that even the most mundane explanation will be extraordinary.....


A mystery is always fun to poke the brain at. Considering the fact that ices will be heavier than the liquid on Titan, this might be the buildup of ice on a reef of ices right under the surface. The hypothesis that it might be foam is one I could have liked, but it is bright, which make that alternative less likely.

Posted by: ngunn Sep 30 2014, 11:54 PM

Try solid ice-foam. Closed cell ice foam on the lake bed would be buoyant in methane. Either it could be formed currently by being erupted from the seabed in some cryovolcanic process or it could be there already just waiting for some disturbance to dislodge it so it can float up.

Posted by: TheAnt Oct 3 2014, 12:43 AM

QUOTE (ngunn @ Oct 1 2014, 01:54 AM) *
Try solid ice-foam. Closed cell ice foam on the lake bed would be buoyant in methane. Either it could be formed currently by being erupted from the seabed in some cryovolcanic process or it could be there already just waiting for some disturbance to dislodge it so it can float up.


Solid ice-foam is a good suggestion, and I'd really like to get the idea to float.

But the process would need to be just right to create foam bubbles of the right size and thickness to make all parts of this island buoyant.
Now that the total size is rather large, this mechanism creating the bubbles would also have to work evenly over a sizeable part of this feature.

So I am stuck in the icy reef, and the ice hypothesis here. =)

Posted by: ngunn Oct 3 2014, 01:13 AM

Here's my thinking. Radar bright means a polar material like ice. Methane-buoyant ice means closed cell foam, like pumice. On Earth, floating pumice disperses due to winds and currents, then eventually washes ashore or sinks as its cell structure breaks down. That seems to fit with what we're seeing.

How would a closed cell ice foam form? I don't know, but here we are on a world with a wide range of aqueous and organic materials. The occasional presence of some suitable surfactant when the material solidifies is not too much to ask.

Newly exposed shoals can I think be eliminated. The liquid level hasn't changed much if at all, and anything shallow would already have been visible whilst just below the surface. There was no hint of it before the 'island' first appeared.

(Note: porous materials, thought to be common on Titan, can be either permeable like sponge or impermeable like expanded polystyrene,)

Posted by: ngunn Nov 11 2014, 09:57 AM

More 'magic islands' - and more bathymetry - in Kraken Mare this time: http://photojournal.jpl.nasa.gov/catalog/PIA19047

(from the Cassini website) http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20141110/

Posted by: Julius Nov 11 2014, 07:17 PM

It's the Nautilus of captain Nemo!

Posted by: marsbug Nov 11 2014, 07:56 PM

I hope it's an unexpected an uniquely Titanian emergent property of the physical and chemical properties of the stuff in the lakes - something truly unique to Titans bizzare environment would be amazing!

Posted by: nprev Nov 11 2014, 09:17 PM

It would be interesting to see if there are any surface temperature changes over time at these sites. However, and please correct me if I'm wrong, I don't think that there's any way to obtain data like that at a useful resolution for these features unless they are very pronounced changes.

Posted by: ngunn Nov 11 2014, 09:27 PM

It sets the mind racing, that's for sure. It reminds me of the uncomprehended phenomena, some benign and some dangerous, on Stanislaw Lem's imagined world Solaris.

The important thing here is the statistics of two. Just one is a remote possibility, but there are never just two of anything. Two in a relatively small sample of the liquid surface in both space and time means that these things pop up quite a lot. I'm left wondering about parts of the lakes and seas that have been imaged only once. Could a few of those other islands be 'magic' ones too? Do the radar images of the 'magic' ones differ in any way that would allow us to distinguish? I also wonder about the lake coastlines. Are there undetected inlets covered with rafts of flotsam disguising the outlines?

Luckily there's VIMS as well as SAR this time, so expect a good science harvest!

Posted by: marsbug Nov 12 2014, 07:36 PM

I have a thought that has been itching me all day, and I'd like to clear it out: Could these magic islands be tension wrinkles in a membrane that sits on top of the lake surface? If the lakes develop a fairly thick layer of something semi-solid, it might buckle and then relax as changing environmental conditions alter the overall tension. The specular reflections observed could be due to a thin liquid layer on the surface. It just struck me when my tea went cold that the patches of wrinkles on the skin looked a bit like the 'island'...

Posted by: Webscientist Nov 12 2014, 08:41 PM

It has been said that some lakes or seas were almost as smooth as a mirror. As you say, why not a thin membrane over le liquid.

A new radar-bright feature about 50 km wide. Difficult to understand!

I see several hypotheses:
--> a detached chunk rising from the sea floor.
--> rising bubbles from hot springs
--> a new island via cryovolcanism
--> snow fall or fall of hydrocarbons or organics (some clouds have been seen over Ligeia Mare)

--> or perhaps, some submarine topography (close to the surface) can be discerned if the incidence angle from the radar mapper is low ( as deduced from the data of the Cassini Huygens website).
...
But the bright structures seem to evolve rapidly. Only plankton formations can change so quickly smile.gif!

Posted by: ngunn Nov 12 2014, 08:49 PM

Here is a terrestrial 'magic island', no plankton required!
http://www.google.co.uk/imgres?imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fen%2F4%2F4b%2FPumice-raft.jpg&imgrefurl=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FFile%3APumice-raft.jpg&h=332&w=539&tbnid=kx8tgDfuazXjRM%3A&zoom=1&docid=HZN5IZfcqWJbDM&ei=TchjVKraIemIsQS43oK4Bw&tbm=isch&client=firefox-a&ved=0CCAQMygBMAE&iact=rc&uact=3&dur=1420&page=1&start=0&ndsp=12
I'm referring to the pumice raft not the new island there.

But I like the wrinkles suggestion for the degree of lateral thinking involved. smile.gif

Posted by: nprev Nov 12 2014, 09:35 PM

MOD NOTE: Let's please remember that rule 1.3 also doesn't permit discussion of plankton...

Posted by: TheAnt Nov 15 2014, 06:45 PM

I have given the hypothesis of marsbug some thought, and considering the possible chemistry of the lakes that could hold dissolved organics that indeed might bond into something of the kind.
An oily organic substance is also possible, it would also dampen waves, but would it be to heavy float?
Lastly we have the foam proposed by the scientists involved in these studies, yes it would float, yet if there's any wind it would move.
Regardless of those alternatives, I label the idea by marsbug a plausible alternative.

Posted by: ngunn Nov 15 2014, 10:16 PM

QUOTE (TheAnt @ Nov 15 2014, 06:45 PM) *
yet if there's any wind it would move.


On the evidence of the recent re-observation of the Ligeia example (post 59) they do move, very slowly and mainly shorewards. That one also spread out over a wider area and faded somewhat after some months. I find it hard to imagine either waves or wrinkles hanging around in the same location for that long.

Posted by: TheAnt Nov 16 2014, 12:55 AM

QUOTE (ngunn @ Nov 15 2014, 11:16 PM) *
On the evidence of the recent re-observation of the Ligeia example (post 59) they do move, very slowly and mainly shorewards. That one also spread out over a wider area and faded somewhat after some months. I find it hard to imagine either waves or wrinkles hanging around in the same location for that long.


Waves seem to be a less likely alternative from what we know now.

That fading out and spreading points to the other plausible alternative as I see this right now, and that would be a collection of clumps of some lightweight organics behaving like the collections of woodpieces, plastic bottles and styrofoam one can find floating together on the ocean nowadays.
Those also move slowly toward the shore and are only sensitive to the wind to some degree, and only sometimes reach harbours and bays since currents easily can disperse them.

What I had written the above I realised it is not anything else but a small variation on the foam idea with the pieces just being less sticky. But I let it stand.

Posted by: marsbug Nov 16 2014, 09:35 PM

QUOTE (TheAnt @ Nov 15 2014, 06:45 PM) *
I have given the hypothesis of marsbug some thought, and considering the possible chemistry of the lakes that could hold dissolved organics that indeed might bond into something of the kind.
An oily organic substance is also possible, it would also dampen waves, but would it be to heavy float?
Lastly we have the foam proposed by the scientists involved in these studies, yes it would float, yet if there's any wind it would move.
Regardless of those alternatives, I label the idea by marsbug a plausible alternative.


Just offering up a thought I had, thank you for devoting some thought to it!

Posted by: titanicrivers Nov 18 2014, 02:16 AM

The excitement over new ‘magic islands’ in Kraken and sunglint from the large sea almost (but not quite) distracts one from an equally exciting bathymetry (white arrow) obtained during T104 and discussed in Photojournal PIA19046 http://photojournal.jpl.nasa.gov/catalog/PIA19046. Here are measurements of the depth of Kraken at the outlet of a “drowned” river valley or ria imaged previously during T 28 http://pirlwww.lpl.arizona.edu/~perry/RADAR/#T28. That one can analyze such earthly appearing but alien analogs from afar is mindboggling.

One might also wonder if the composition of the upper reaches of the drowned river bring a different mix of liquid hydrocarbons to the estuary akin to the fresh water-salt water mixing in many of earth’s drowned valleys. The figure below puts the drowned river valley in perspective with a broader view of SAR T28 and topographic data from PIA10353 (also in Photojournal) http://photojournal.jpl.nasa.gov/catalog/?IDNumber=pia10353 and compares it with the Susquehanna river ria known as the Chesapeake Bay on the east coast of the USA. In the figure K = Kraken, M = Mayda Insula and L = Ligeia. The Chesapeake Bay is roughly 300 km long from the Susquehanna River inlet (top red arrow) to the Atlantic Ocean outlet (A) photo credit NASA/Landsat https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAYQjB0&url=http%3A%2F%2Fdisc.sci.gsfc.nasa.gov%2Fneespi%2FgesNews%2Fges_disc_basins_project&ei=LKpqVNCVJ4b6yAScqoHoBg&bvm=bv.79908130,d.aWw&psig=AFQjCNFFvv9iI91RONM0Prj8FRjV4Jq7gg&ust=1416362873092336.




Posted by: rlorenz Nov 23 2014, 04:45 AM

QUOTE (titanicrivers @ Nov 17 2014, 09:16 PM) *
One might also wonder if the composition of the upper reaches of the drowned river bring a different mix of liquid hydrocarbons to the estuary akin to the fresh water-salt water mixing in many of earth’s drowned valleys.


Very astute speculation. Entirely possible, both on the small scale you describe, and perhaps on the larger scale - it could be that the entire Ligeia-Kraken system has a methane/ethane variation akin to the salinity gradient between the sea of Azov/Black Sea/Mediterranean or Baltic/North Sea, where ethane (+propane etc.) are essentially analogs of salt (i.e. an involatile solute tracer) and the enhanced precipitation at high latitudes leads to 'fresher' composition there... See http://www.lpl.arizona.edu/~rlorenz/flushing.pdf

It may be that radar data (radiometry, and/or attenuation measurements in bottom-sounding altimetry) or bistatic radio reflection experiments can constrain the compositions somewhat. Possibly also near-IR spectroscopy from VIMS.

Posted by: ngunn Nov 23 2014, 11:31 AM

Should we also expect a vertical 'salinity' gradient within the lakes, as we find in the Black Sea? Searching around I found liquid densities of 0.421 and 0.546 for methane and ethane respectively - quite a large difference. I note that in the Bosphorus there is a deep salty current flowing in and fresh surface water flowing out at one and the same time. Maybe something similar happens at the Throat of Kraken.

Posted by: Ron Hobbs Nov 23 2014, 03:35 PM

QUOTE (titanicrivers @ Nov 17 2014, 06:16 PM) *
That one can analyze such earthly appearing but alien analogs from afar is mindboggling.


Yes! And that I can 'listen' in on this conversation is equally so. Thank you so much for that and for the links.

Ron

Posted by: Juramike Nov 23 2014, 04:59 PM

Once again, Titan has the potential to be even more complicated than the simple Earth story. One of the fun possible "twists" in the story on Titan compared to Earth is that fluids percolating through the subsurface of Titan can exchange with clathrates. That would depend on the exact structure of the clathrates (structure I or structure II) and the kinetic rate of exchange (flow rate, contact time, initial mix, etc.) with the clathrates in the subsurface. So the hydrocarbon and nitrogen fluid mix going into the subsurface can be different than the fluid mix coming out. Think of it as having an ethane or methane sponge that sucks up one or two of the hydrocarbons.

Check out: Mousis et al., 2014: http://arxiv.org/pdf/1405.6588.pdf

Bottom line (!) is that you could have a propane-rich subsurface spring popping up under the surface of one of the lakes. But that would all depend on the kinetic rates, structures of the subsurface and the starting mix of the fluids.

So it has the potential to be a very, very complex system. As always, more laboratory work is needed. smile.gif

And as Ralph likes to point out during his presentations, most of the calculations are done assuming everything is at equilibrium. As we know from our terrestrial experiences, very few of us are ever at equilibrium. Last time I checked, my relative humidity was a loooooong ways away from 100% saturation (the equilibrium state). Using equilibrium calculatoins for Titan is a good start to see the idealized case, but the reality on (and under) the ground will be even more complicated.

Posted by: rlorenz Nov 24 2014, 03:09 AM

QUOTE (ngunn @ Nov 23 2014, 06:31 AM) *
Should we also expect a vertical 'salinity' gradient within the lakes, as we find in the Black Sea? Searching around I found liquid densities of 0.421 and 0.546 for methane and ethane respectively - quite a large difference. I note that in the Bosphorus there is a deep salty current flowing in and fresh surface water flowing out at one and the same time. Maybe something similar happens at the Throat of Kraken.


Indeed. Same thing happens at Gibraltar (as I noted in my Throat of Kraken paper). Stratification is something I'm looking into with Tetsuya Tokano. Stevenson and Potter back in the mid-80s suggested a seasonal CH4 layer might form on top of a denser C2H6 layer (but they thought it would happen in winter - it rather seems now instead it might be a summer rainfall thing). Transient layers of fresh water do form on Earth's seas (arctic freshwater pool, Amazon plume, etc.) - the question is how quickly things may get mixed up. Tokano in 2009 looked at thermal stratification. But with methane/ethane/nitrogen/etc the composition effects and temperature effects can trump each other - there's a phenomenon ('rollover') where this has happened in LNG storage tanks - am writing something up about this in a titan context.

Posted by: titanicrivers Feb 13 2015, 01:13 AM

Antoine Lucas’ de-noising technique featured in today’s Photojournal article http://photojournal.jpl.nasa.gov/catalog/PIA19051 and http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20150211/ provides an interesting perspective and relatively noise free view of the drowned river valley of T28. The small stream tributaries one might have anticipated are nicely shown in the de-noised view (included below).


Posted by: titanicrivers Feb 15 2015, 01:07 AM

The ‘drowned’ river in the de-noised, despeckled perspective http://photojournal.jpl.nasa.gov/catalog/PIA19051 with topography from PIA10353 http://photojournal.jpl.nasa.gov/catalog/?IDNumber=pia10353 overlain is shown below. Titan’s rivers are said to show little in the way of erosive action http://newsoffice.mit.edu/2012/river-networks-on-titan-0720 but I wonder if the area circled might be a substantial valley cut into the icy uplands. A rough estimate based on the elevation scale shows a 400m difference between the river bed and adjacent upland over a relatively short distance of 5-10 km.


Posted by: marsbug Feb 15 2015, 12:35 PM

Looking at the side by side comparison images in the press release, http://www.jpl.nasa.gov/news/news.php?feature=4483, the despeckled images look much less like I was expecting - like they have giant seaweed draped ove the Titanian surface biggrin.gif biggrin.gif biggrin.gif Parts of it just look... too smooth!

Posted by: 0101Morpheus Feb 15 2015, 03:16 PM

Couldn't they do that with any object mapped by radar? Like, lets say, Venus?

Posted by: titanicrivers Aug 29 2015, 09:42 PM

A nice article on Titan’s lakes and seas appears in the October 2015 issue of Astronomy magazine. http://www.astronomy.com/magazine/2015/08/web-extra-titans-seasons-slowly-change?utm_source=SilverpopMailing&utm_medium=email&utm_campaign=ASY_News_Sub_150828_Final&utm_content=&spMailingID=23378837&spUserID=MTE2MjkxMzA4NjI2S0&spJobID=622740089&spReportId=NjIyNzQwMDg5S0. PIA 18432 http://photojournal.jpl.nasa.gov/catalog/PIA18432 is featured on the cover and on p. 25 of this publication. The author, Alexander G. Hayes, provides an authoritative summary of what is known about Titan’s seas including the composition, radio wave absorptivity and depth of the major bodies of liquid on Titan http://www.hou.usra.edu/meetings/lpsc2014/pdf/2341.pdf. SAR images of the “magic islands” in Ligeia Mare, a nice comparison of rounded surface ‘boulders’ on Titan and Earth and discussion about Titan’s lake distribution change with time are highlighted.

Posted by: HSchirmer Aug 29 2015, 11:18 PM

QUOTE (rlorenz @ Nov 23 2014, 04:45 AM) *
QUOTE (titanicrivers @ Nov 17 2014, 09:16 PM)

One might also wonder if the composition of the upper reaches of the drowned river bring a different mix of liquid hydrocarbons to the estuary akin to the fresh water-salt water mixing in many of earth’s drowned valleys.

Very astute speculation. Entirely possible, both on the small scale you describe, and perhaps on the larger scale - it could be that the entire Ligeia-Kraken system has a methane/ethane variation akin to the salinity gradient between the sea of Azov/Black Sea/Mediterranean or Baltic/North Sea, where ethane (+propane etc.) are essentially analogs of salt (i.e. an involatile solute tracer) and the enhanced precipitation at high latitudes leads to 'fresher' composition there...


Neat ideas- there appears to be an impact crater in the Titan image, which reminds me that there is a large crater under Chesapeak bay.
That crater was found because of odd groundwater flow in that area, freshwater, regular sea water and brine.
One theory is that the heat from the chesapeak impact vaporized the water from deep aquifer seawater to create a concentrated brine.

Very interesting to think about what chemistry and fractionation you might get from an impact into hydrocarbon seas.

Posted by: Mongo Jan 15 2016, 02:08 AM

http://arxiv.org/abs/1601.03364

QUOTE
We document the similarities in composition between the equatorial basins Tui Regio, Hotei Regio, and other 5-μm-bright materials, notably the north polar evaporites, by investigating the presence and extent of an absorption feature at 4.92 μm. In most observations, Woytchugga Lacuna, Ontario Lacus, MacKay Lacus, deposits near Fensal, some of the lakes and dry lake beds south of Ligeia, and the southern shores of Kraken Mare share the absorption feature at 4.92 \um observed in the spectra of Tui and Hotei. Besides Woytchugga and at Fensal, these 5-μm-bright deposits are geomorphologically-substantiated evaporites. Thus, the similarity in composition strengthens the hypothesis that Tui and Hotei once contained liquid. Other evaporite deposits, however, do not show the 4.92 \um absorption, notably Muggel Lacus and the shores of Ligeia Mare at the north pole. This difference in composition suggests that there are more than one kind of soluble material in Titan's lakes that can create evaporite and/or that the surface properties at the VIMS wavelength scale are not uniform between the different deposits (crystal size, abundance, etc). Our results indicate that the surface structure, composition, and formation history of Titan's evaporites may be at least as dynamic and complex as their Earth counterparts.



Posted by: ngunn Jul 22 2016, 07:47 AM

Some of the best ISS overviews of the northern lakes are appearing now:
http://saturn-archive.jpl.nasa.gov/multimedia/images/raw/casJPGFullS95/N00263235.jpg

EDIT: This is from the Ciclops 'looking ahead:
"Late on July 26, ISS will acquire a series of cloud tracking observations covering Titan’s north polar region.

On July 27 Titan will be observed during a calibration observation of the polarizer filters on ISS."

I will be looking to see if the lakes look markedly different through the different polarizers.

Posted by: Ian R Jul 22 2016, 11:32 PM

This is a 'color' version using the CB3, MT1 and MT3 filters:


Posted by: volcanopele Jul 23 2016, 04:01 PM

Going for the MEX VMC look? tongue.gif

Looks very nice.

Posted by: Ian R Jul 23 2016, 07:00 PM

Thanks Jason! Yeah, I've been looking for a way to give the CB3 frames some color for a while now, and seemed to have hit upon a recipe that works:

https://flic.kr/p/KeaTTz
https://flic.kr/p/KeaTTz by https://www.flickr.com/photos/10795027@N08/, on Flickr

https://flic.kr/p/JhFvwQ
https://flic.kr/p/JhFvwQ by https://www.flickr.com/photos/10795027@N08/, on Flickr

Posted by: Ian R Aug 4 2016, 11:43 PM

The latest view from August 3rd:


Posted by: Ian R Aug 6 2016, 11:57 AM

And from the following day, August 4th:


Posted by: Julius Aug 11 2016, 03:52 AM

The study by Poggiali et al published describes radar studies which seem to show fluid filled valleys draining into Ligeia Mare. The continuous presence of fluid within these canyons in the absence of precipitation would thus seem to indicate a subsurface source of liquid methane?

Posted by: Ian R Sep 12 2016, 03:40 AM

https://flic.kr/p/LboV6h
https://flic.kr/p/LboV6h by https://www.flickr.com/photos/10795027@N08/, on Flickr

Posted by: eliBonora Sep 13 2016, 02:46 PM

Here's my version of Titan on 10 September
red, gr, bl and uv filter at right and 3 cb3 stack at left

In this view, with Sinlap crater in the middle, we can see: Kraken Mare, Lingeia Mare, Jingpo Lacus, Bolsena Lacus, Ledoga Lacus and Punga Mare.

https://flic.kr/p/M3KZvz

Posted by: Ian R Sep 23 2016, 09:42 AM

The latest observation of Titan (from the 21st):


Posted by: Ian R Sep 27 2016, 04:46 AM

September 23rd:


Posted by: Ian R Oct 12 2016, 03:39 PM

October 10th:


Posted by: Ian R Oct 17 2016, 12:54 AM

October 15th:


Posted by: Ian R Nov 2 2016, 11:50 AM

I've processed 36 frames of Titan taken over a period of three hours; numerous clouds are seen forming and dissipating

http://imgur.com/a/i5VS6

Posted by: JRehling Nov 2 2016, 05:12 PM

That video of cloud dynamics is great, Ian!

Posted by: Phil Stooke Nov 3 2016, 12:22 AM

I'm really impressed with this work, Ian - please keep it up! It's a great window into what is going on in that complex atmosphere.

Phil

Posted by: Ian R Nov 3 2016, 10:01 AM

Thanks fellas! smile.gif I'm endlessly fascinated by Titan, so I'll no doubt continue to cook up image products even after Cassini has plunged into Saturn (the PDS data is so much nicer to work with).

And this is a stack of ten ratioed frames:

https://flic.kr/p/MRBkGV
https://flic.kr/p/MRBkGV

Posted by: ngunn Nov 4 2016, 04:46 PM

A belated thank you from me too for the superb work here on the sea-and-cloudscapes, and as ever to the Cassini team for obtaining and releasing that spectacular sequence of images.

Posted by: titanicrivers Nov 4 2016, 10:24 PM

AWESOME images IAN! I can only echo the great tribute of thanks of ngunn above.

Posted by: volcanopele Nov 4 2016, 11:22 PM

My processed version of this observation is now up!

http://photojournal.jpl.nasa.gov/catalog/PIA21051

Posted by: Decepticon Nov 4 2016, 11:42 PM

Jaw dropping!

This image stacking works well on Titan!

Posted by: Ian R Nov 5 2016, 12:15 AM

Way to totally trump me, Jason! laugh.gif Awesome work, sir. And is that hazes and/or fog I see hovering over Ladoga Lacus?

Posted by: volcanopele Nov 5 2016, 03:16 PM

Yes, there is fog or faint clouds moving over Ladoga Lacus over the course of the observations, as well as in Trold Sinus in eastern Kraken Mare and moving over parts of Punga Mare later in the observation.

Posted by: ngunn Nov 5 2016, 10:55 PM

QUOTE (volcanopele @ Nov 5 2016, 04:16 PM) *
Trold Sinus in eastern Kraken Mare


Is there a published map showing the names of bays and headlands in Titan's lakes and seas? If so I've missed it so far.

One thing that strikes me when I see these images, both in Ian R's stack and in Jason's superb animation, is that Ligeia Mare as a whole appears more hazy than equivalent parts of Kraken Mare at the same distance from the terminator. I don't know if that's a clue to something on Titan, an imaging thing, or just my eyes.

Posted by: Ian R Nov 13 2016, 05:18 AM

QUOTE (ngunn @ Nov 5 2016, 10:55 PM) *
Is there a published map showing the names of bays and headlands in Titan's lakes and seas? If so I've missed it so far.


There is indeed such a map, courtesy of the USGS: http://planetarynames.wr.usgs.gov/images/titan_northpole_new.pdf

A full set of maps can be found here: http://planetarynames.wr.usgs.gov/Page/TITAN/target

Posted by: ngunn Nov 16 2016, 11:04 AM

Thanks for the links. smile.gif I have been examining the most recent lake images from November 14, some of which such as this one http://saturnraw.jpl.nasa.gov/multimedia/images/raw/casJPGFullS96/N00272121.jpg were taken though a polarising filter. I look forward to seeing how these look when processed.

Posted by: jccwrt Dec 16 2016, 05:01 AM

Here's a mosaic of Titan taken during the T-99 flyby. We've got a good view of Ligeia and Punga Mare, and Kraken Mare stretches away onto the night side. We've also got good views of Dilmun, Shangri-La (bottom left) and Menvra Crater (bottom right).

https://flic.kr/p/Q2TCyw
https://flic.kr/p/Q2TCyw by https://www.flickr.com/photos/132160802@N06/, on Flickr

Posted by: Ian R Dec 22 2016, 08:28 PM

This two-frame mosaic from December 20th appears to show a large wisp of cloud in the vicinity of the 'kissing lakes', aka Abaya Lacus:


Posted by: volcanopele Dec 24 2016, 03:24 AM

I think this is probably the best view of Kraken Mare to date.

Posted by: ngunn Dec 24 2016, 11:34 PM

Agreed, that's a superb view. The channel connecting Jingpo Lacus to Kraken Mare is particularly striking. Also the view of the 'toe of Italy' area, not well imaged by SAR, is pretty good. It could be a separate lake linked to Kraken by a similar channel.

Posted by: JRehling Dec 27 2016, 06:47 AM

I think there's a lot of subtle detail here that might be hidden from the eye.

I took the "summer clouds animation" (PIA21051: Watching Summer Clouds on Titan) and constructed a rough median frame by computing the pixelwise medians from the first, middle, and last frames. Then, I created a new animation which subtracts the median from each of the frames in the original work by Jason Perry. I think this makes subtle polar clouds (fog banks?) much more obvious: I count at least nine at one point. This also makes the rotation of the winds over a large area around the pole quite evident.

In order to post here, I needed to shrink the animation 4x… I think the key details are still obvious.


 

Posted by: Ian R Dec 28 2016, 04:06 AM

Very neat trick, J. I wish I had thought of that!

Conversely, stacking the frames brings out subtle details in the shorelines of the lakes and within the bright evaporite:


Posted by: JRehling Dec 28 2016, 04:28 AM

Processing my own astrophotography falls, usually, into one of two modes: Deep sky objects, with incredible detail that is usually very subtle, and planetary objects, where the effects of the Earth's atmosphere is the major obstacle. In my version, Ian, and yours, we basically tackled this data set in those two ways. I used the median-subtraction to bring out faint details, and you used image stacking to compensate for the blurring effects of the atmosphere (in this case, Titan's).

This is basically a 3-D dataset, so there are many ways to rework it. Perhaps we've barely scratched the surface.

Posted by: antipode Dec 28 2016, 06:45 AM

This beautiful image seems to cover a few areas that, to the best of my knowledge, have NOT been covered by radar swaths.

I see several sizeable lakes in these areas. Have they been named?

P

Posted by: ngunn Dec 28 2016, 01:01 PM

Another thing I've noticed in Ian's stacked image is the suggestion of a large circular feature, similar in size to Menrva and to the northeast of it. Comparing just by eye with the Titan map on Ciclops I estimate its position as very approximately LAT+45 LON 70. The circle itself is brightish and its interior shows stronger light and dark mottling than surrounding areas at the same latitude.

EDIT: Here is a crop of the feature I'm referring to -


 

Posted by: JRehling Dec 29 2016, 06:42 PM

Thanks for the addition of the close-up, ngunn. That is an intriguing feature. It seems like some sort of combination of volcanic and lake formation might be involved.

Posted by: titanicrivers Dec 29 2016, 10:24 PM

QUOTE (ngunn @ Dec 24 2016, 05:34 PM) *
Agreed, that's a superb view. The channel connecting Jingpo Lacus to Kraken Mare is particularly striking. Also the view of the 'toe of Italy' area, not well imaged by SAR, is pretty good. It could be a separate lake linked to Kraken by a similar channel.

I wonder if the ‘channel’ going from Jingpo to Kraken is more the result of the lower resolution of the ISS image. We have good views of the area from the T 25 SAR and a very nice denoised view of the beginning of the ‘channel’ from Antoine Lucas’ version of Jingpo Lacus shown in Photojournal here: http://photojournal.jpl.nasa.gov/catalog/PIA19053 (BTW the caption for the image contains an error stating …”The three leftmost image pairs show bays and spits of land in Ligea Mare, one of Titan's large hydrocarbon seas. The rightmost pair shows a valley network along Jingpo Lacus, one of Titan's larger northern lakes.”… I’d suggest this should read: the two left most image pairs show bays and spits of land in Ligeia Mare, the next pair are of Jingpo Lacus and the rightmost pair show a valley network along Kraken.
Anyway the figure below overlays the T-25 SAR on IAN R’s processed mosaic from UMSF (sharpened and enhanced) and identifies seas, islands and more obvious channels.
Changes may have occurred since the T-25 SAR to ‘dampen’ the broad area making it appear as a channel, but a continuous channel … it appears not likely.


Posted by: ngunn Dec 29 2016, 10:49 PM

There is a big difference between what the RADAR sees and the near IR images. I'm not sure which is the best guide to the topography or the drainage.

Posted by: ngunn Dec 29 2016, 10:54 PM

Refering to the circular feature: maybe impact should be considered too?

Posted by: Ian R Dec 30 2016, 04:58 AM

QUOTE (ngunn @ Dec 29 2016, 10:54 PM) *
Refering to the circular feature: maybe impact should be considered too?


This feature has intrigued me for some time, ever since I spied it on a medium range shot from 2013:



Nicknaming it the 'Bullseye', I spotted it again on the VIMS mosaic taken during the T-114 flyby; this is a crop of an undistorted version of PIA20016:



Finally, here is our region of interest with the topographic map (courtesy of Ralph Lorenz, et al) lain over the ISS basemap PIA20713:



It would appear that the 'Bullseye' is possibly a depression, perhaps even an ancient impact crater that has degraded over time. It may also be analogous to Hotei Regio, which is suspected to be a dry lake bed, harking back to seasonal conditions that favored temperate latitudes. Who knows? cool.gif


Posted by: Ian R Jan 3 2017, 08:17 AM

With the new year comes changes on Titan: just look at the size of the cloud bands girding the upper latitudes!


Posted by: JRehling Jan 3 2017, 04:54 PM

QUOTE (Ian R @ Jan 3 2017, 01:17 AM) *
With the new year comes changes on Titan: just look at the size of the cloud bands girding the upper latitudes!


Cloud formation can be a sort of binary switch that makes visible the variations in relative humidity that are otherwise invisible.

One thing that can come out of this beautiful and mesmerizing data set is an understanding of Titan weather, using this sparse "boolean" data to interpolate/extrapolate to a wider range of times, places, conditions, etc.

In the animation I made showing the polar clouds, it would be particularly interesting to identify the times and places where clouds/fog began. It seems like perhaps a weather front is moving over lakes, causing clouds to initiate when it crosses over them. But maybe I'm primed to expect this because I used to live near and downwind of the Great Lakes on Earth.

Posted by: rlorenz Jan 4 2017, 04:42 AM

QUOTE (JRehling @ Jan 3 2017, 11:54 AM) *
Cloud formation can be a sort of binary switch that makes visible the variations in relative humidity that are otherwise invisible.
One thing that can come out of this beautiful and mesmerizing data set is an understanding of Titan weather, using this sparse "boolean" data to interpolate/extrapolate to a wider range of times, places, conditions, etc.


You're quite right - even austere datasets such as we have here can be interpreted in a probabilistic way, using Bayesian reasoning / Monte Carlo methods
- the same is true of the Boolean question of 'are there waves on the sea surface on Titan (you can have calm days during the windy season and vice versa,
so perfect/accurate measurement is perhaps less important than frequent measurement)
Another example - not related to Titan - is whether rocks moved or not
https://www.lpl.arizona.edu/~rlorenz/climatechange_racetrack.pdf

Posted by: alan Jan 4 2017, 10:13 PM

animation of clouds

https://twitter.com/kevinmgill/status/815718720014196736

Posted by: ngunn Feb 19 2017, 04:24 PM

More superb views of lakes and clouds today: https://saturnraw.jpl.nasa.gov/multimedia/images/raw/casJPGFullS98/N00277002.jpg

Posted by: titanicrivers Mar 16 2017, 02:24 AM

Juramike (Mike Malaska) has a new article in Icarus on the possibility of Nitrogen bubbles affecting large patches of the N polar seas as seasonal changes occur. A great image of the N polar region and a summary of the article are found on the Cassini website https://saturn.jpl.nasa.gov/news/3008/experiments-show-titan-lakes-may-fizz-with-nitrogen/


Posted by: Ian R Mar 25 2017, 02:02 PM

https://flic.kr/p/TfbhNx
https://flic.kr/p/TfbhNx

https://flic.kr/p/Tfab3v
https://flic.kr/p/Tfab3v

Posted by: TheAnt Apr 21 2017, 04:24 PM

The features that appeared then to disappeared in liquid on Titan have indeed turned out to be foamy bubbles.
This finding is described in a paper in https://www.nature.com/articles/s41550-017-0102 and a popularized treat on the subject is found in https://www.universetoday.com/135111/bubbly-streams-titan/.

Posted by: nprev Apr 21 2017, 08:52 PM

Much of this work was done by UMSF moderator Juramike, who is quoted extensively in the Universe Today article. wink.gif

Posted by: JRehling Apr 22 2017, 03:45 AM

This fizzy seas result is one of the most science-fiction-like things I've read in planetary science. It's like something out of a comic book. Congratulations, Mike.

Posted by: rlorenz Apr 22 2017, 03:40 PM

QUOTE (TheAnt @ Apr 21 2017, 11:24 AM) *
The features that appeared then to disappeared in liquid on Titan have indeed turned out to be foamy bubbles.


No they have not. The study (to which I also contributed) showed that nitrogen bubbles could be formed in certain circumstances. Such bubbles
could account for some transient phenomena observed on Titan's seas (aka 'the magic island' observed in radar) but they
cannot account for all the transient features observed (notably by VIMS, which only sees the top fraction of a millimeter of
material).

A more parsimonious theory is that surface roughness (either locally wind-driven, i.e. 'catspaw', or nonlocally - i.e. wind-driven
currents) explains all the observed transients.

Bubbles are still fun to think about, though.

Posted by: Juramike Apr 22 2017, 11:45 PM

Yeah. A funny thing happened on the way to the Universe Today article....

About a month ago we had a press release that presented our Icarus paper on experiments to figure how much nitrogen goes into lake fluids. Lotsa fun implications. Lakes "breathing" in and out, gas release from liquid mixing, cool stuff (!). And we stated pretty much "Oh yeah, and bubbles might possibly could be an explanation for observations of Magic Islands in Titan seas." I mean, sure, it's still on the list of possible suspects.

A month later, another paper comes out in Nature Astronomy that describes model calculations (not using our new lab data, I might add) that had a press release saying that the problem was solved.

And somehow in a funky twist, the Universe Today article combined the Nature Astronomy article's press release first paragraphs with the last paragraphs of our earlier press release.

So basically, we got an extra bonus 15 minutes of fame riding on the back of a later paper that came to some of the same conclusions that we'd already published earlier.

I'm really not quite too sure what to make of all this....

But as for the observed Magic Islands in the lakes, I agree with Ralph that wind is a good (and leading) suspect for Magic Islands. But the properties of Titan lakes definitely causes some funkiness. (As in, no freezing of methane on Titan - but that's not a new discovery, our lab experiments just help with the "why".)

Posted by: ngunn Apr 23 2017, 07:23 AM

I have a question about the way patches of bubbles might produce RADAR reflections. Please excuse me if the answer is already in one of the papers: I don't have access. Are we talking about bubbles distributed through the body of the liquid or a raft of some sort of scum accumulating on the surface?

Posted by: Webscientist Apr 23 2017, 12:28 PM

Thanks Ralph and Mike for your courageous experimental study about the bubble phenomenon. Risky I guess with all these volatile hydrocarbons... unsure.gif
In Ligeia Mare, I note that the coastline near the "Magic Island" is particularly irregular with numerous peninsulas or bays.
I can imagine strong erosional processes in that area as well as potential disturbances in streams.

Posted by: rlorenz Apr 23 2017, 07:52 PM

QUOTE (ngunn @ Apr 23 2017, 02:23 AM) *
I have a question about the way patches of bubbles might produce RADAR reflections. Please excuse me if the answer is already in one of the papers: I don't have access. Are we talking about bubbles distributed through the body of the liquid or a raft of some sort of scum accumulating on the surface?


These are quite distinct hypotheses. Floating material (e.g. pumice rafts, or some sort of bubble foam) could explain both radar and near-IR brightness, as could surface roughness from wind or currents.

A bubble plume, with voids in the methane column, could give radar backscatter, but not near-IR.

A bubble plume would be expected to be anchored to the seafloor somehow ; floating material would be pushed around a lot by wind, so the magic island's recurrence at one spot might argue somewhat against it, although some sort of pumice analog continuously/episodically released from a seafloor volcano would have some preference for location, I guess.

Posted by: Juramike Apr 24 2017, 05:35 AM

No, a bubble plume due to compositional mixing would not be anchored to the lake floor. It would be present anywhere there was a lower layer of ethane-richer fluid overlain by methane richer-fluid. It could be anywhere. And if there was a "bubble event" it could migrate around as the different portions of the lake hit compositional equilibrium at different times. It'd be really fun and exciting to watch.

There could, however, be places more prone to compositional mixing. Places where local winds are more prone to stir up the lakes fluids, cause mixing, and then generate a bubble-splosion. This could explain Magic Islands reappearing at same location (after a recharge of compositional disequilibrium.)

(Please note that Occam is starting to have a 5-o'clock shadow at this point....)




Posted by: ngunn Apr 24 2017, 08:11 AM

Thanks for the informative replies.

QUOTE (rlorenz @ Apr 23 2017, 08:52 PM) *
Floating material (e.g. pumice rafts, or some sort of bubble foam) could explain both radar and near-IR brightness, as could surface roughness from wind or currents.
A bubble plume, with voids in the methane column, could give radar backscatter, but not near-IR.


Do we have any near-IR evidence either way for the original 'magic island'? If so I missed it.

QUOTE (Juramike @ Apr 24 2017, 06:35 AM) *
No, a bubble plume due to compositional mixing would not be anchored to the lake floor.


So it seems to me we have two separate questions to answer regarding any bubble-related explanation for the transient features. What mechanism generates the bubbles, and in which way are they rendered visible?

Mike, I wonder if you have any ideas on surfactant materials that might plausibly be present in Titan's seas? Perhaps this is another area where experimentation could prove fruitful. Can you produce a long-lasting foam under Titan conditions?

Posted by: stevesliva Apr 24 2017, 08:20 PM

I find myself wondering whether gravels entrained by a dense river would end up floating on top of a less-dense sea.

Posted by: rlorenz Apr 24 2017, 10:21 PM

QUOTE (Juramike @ Apr 24 2017, 01:35 AM) *
(Please note that Occam is starting to have a 5-o'clock shadow at this point....)


LOL! Quite. Note that I did say 'expected' to be anchored..... as you say, anything is "possible"

Posted by: Juramike Apr 28 2017, 06:02 AM

QUOTE
So it seems to me we have two separate questions to answer regarding any bubble-related explanation for the transient features. What mechanism generates the bubbles, and in which way are they rendered visible?

Mike, I wonder if you have any ideas on surfactant materials that might plausibly be present in Titan's seas? Perhaps this is another area where experimentation could prove fruitful. Can you produce a long-lasting foam under Titan conditions?


Two ways you can make bubbles.
1) Heat up Titan liquids. Solubility of nitrogen in methane really drops off on heating.

2) Compositional mixing. Mix a liquid containing lotsa methane/nitrogen with liquid containing ethane (which doesn't like nitrogen so much). The excess will come out.


As for surfactants, methane (and ethane but less so) is a lousy solvent. So any surfactants that could dissolve to an appreciable and useful extent is a very short list. In our experiments we get a huge amount of bubbles generated. So all our calculations were assuming instant N2 release and bubbles and we didn't worry about long-lasting foams.

Posted by: Juramike Apr 28 2017, 06:05 AM

Oh! And I just realized my paper is freely available until May 11th.

So download early, cite often!

Malaska, M.J., Hodyss, R., Lunine, J.I., Hayes, A.G., Hofgartner, J.D., Hollyday, G., Lorenz, R.D., 2017. Laboratory measurements of nitrogen dissolution in Titan lake fluids. Icarus, 289, 94-105. doi: 10.1016/j.icarus.2017.01.033.

Link here: https://authors.elsevier.com/a/1UlV4_Rp9r90d



(The Supplementary material is freely available too. We dumped all the lab data as text files and lotsa explanatory text in the Supplementary Materials. It's in a zip file, but is only 285 kilobytes compressed. Enjoy!)

Posted by: ngunn Apr 28 2017, 07:49 AM

Thanks Mike. smile.gif We're off on holiday today so this will be great in-flight reading.

Posted by: hendric May 3 2017, 03:20 PM

So, how long before you guys wrangle a stream/sand table into one of those refrigerated chambers? Smash a little water ice "sand" and place an ethane lake at the shallow end, and make it rain! smile.gif

"Try this at home" is not likely, but maybe a similar experiment could be done with seltzer water and another commonly available solvent - alcohols or mineral oils?

It's intriguing to think there could be an equivalent to thermohaline (thermonitro?) circulation on Titan. Colder parts of the seas cause surface methane to dissolve nitrogen and increase in density, descending to the bottom and drawing in new low density methane from warmer areas.

So based on my read of Mike and Ralph's excellent paper, methane rain would be colder, denser, and carrying more nitrogen than the lake they are flowing into - so my bet is it tends to stay in submerged valleys as it enters the lake. If there is a gradient in the lake of methane/ethane mixing, then as the flow reaches deeper areas it will start encountering/mixing with more ethane, causing nitrogen release. Though I would expect this to happen all around the lake margins where the rain is occurring, instead of a single location. So if the Magic Island is caused by nitrogen bubbles, it must be something more localized like a thermal vent. And once these events start, they could be self-sustaining. Just amazing.

Mike, based on your comments, it sounds like the N2 doesn't stay supersaturated very easily in the liquids. So it's not like a glass of cold water warming up and bubbles forming on its sides, but Mentos/Diet Coke?

Sorry getting into this so late, life and all that.

Posted by: Juramike May 5 2017, 02:14 PM

Nitrogen is perfectly happy to stay in liquid methane.

But if you "warm"* it up a little, decrease atmospheric pressure a little, or add a little ethane, then the nitrogen no longer be happy and it will come out.

*"warm" is relative, we're still at around 91 K-ish. But there's already a huge difference in the amount of dissolved nitrogen between methane at 85 K and methane at 95 K.

The expected densities change a bit due to saturation with nitrogen and we calculated that out and showed it in one of the figures in the paper. For liquids flowing across the surface, I'd think they might be the same temperature as the surroundings. Actually, if a methane/nitrogen river flows into a lake with a little ethane mixed in the higher density of ethane should win out and the incoming stream liquids would be less dense than the ethane-methane-(+not-as-much nitrogen) mix. The new liquids would want to float. So you might get a neat-o layering effect with methane-nitrogen on top, and slightly higher density ethane mix on the bottom. (Think tequila sunrise). That would set up the system for eventual compositional mixing/nitrogen exsolvation bubble-time.

Whee!

Posted by: ngunn Aug 14 2017, 04:49 PM

Recent views of the lakes and seas have been some of the best ever. I hope one or more of our image experts will make mosaics. This is just a single example from the raw images: https://saturnraw.jpl.nasa.gov/multimedia/images/raw/casJPGFullS101/N00286802.jpg

Posted by: atomoid Aug 15 2017, 01:19 AM

thanks! i wonder if this white blotchy streak https://saturn.jpl.nasa.gov/raw_images/421698/ is a cloud formation, as it may be visible only at a narrow reflection angle, since its very dim in most https://saturn.jpl.nasa.gov/raw_images/421738/, it also seems to have a dim complimentary dark streak (shadow?) next to (beneath?) it, which seems more apparent in https://saturn.jpl.nasa.gov/raw_images/421708/ the white streak..


Also, some of the recent https://saturn.jpl.nasa.gov/raw_images/420988/ are not to be missed as well, need a gif animation...

Posted by: ngunn Sep 13 2017, 04:06 PM

Right at the last minute more wonderful lake portraits. What a store of treasure Cassini has provided!
https://saturn.jpl.nasa.gov/images/casJPGFullS101/N00289114.jpg

Posted by: atomoid Sep 19 2017, 10:56 PM

EDIT: i posted to the wrong thread, so here is a stitch of a collection of those new Titan lakes https://saturn.jpl.nasa.gov/raw_images/426179/


Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)