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
Wow, they are great. This is one with a bit of a stretch and cleanup.
Phil
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
Three-frame WAC mosaic of Titan's northern wetlands, with a *tentative* identification of PUNGA MARE labelled as 'PM'.
Is any high-contrast spot safely assumed to be a lake?
At this latitude, I think that's a fairly safe assumption.
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.)
The same region of Titan's north pole, as seen by radar (cropped from PIA10008):
Labelled version:
http://postimg.org/image/3uvjfogdz/
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
"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).
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
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
Beautiful! I was really hoping someone would do that, so my hearty thanks.
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
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.
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:
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
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.
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?
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.
Fantastic work Jason!
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.
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.
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...
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
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?
Those are clouds.
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?
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
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.
Is this a 'lake effect'? Is there much of a difference between the liquid and the overlying atmosphere?
P
For a weather nut like me, that is awesome .
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!)
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.
I presume this is the estuary (E) connecting Ligeia mare (L) and Kraken mare (K).
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.)
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.
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?
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
Yep, there seems to be a cloud right between Muggel and Ligeia, alright.
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.
The 'Magic Island' returns: http://photojournal.jpl.nasa.gov/catalog/PIA18430
I love mysteries, especially when their circumstances mandate that even the most mundane explanation will be extraordinary.....
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.
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,)
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/
It's the Nautilus of captain Nemo!
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!
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.
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!
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'...
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 !
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.
MOD NOTE: Let's please remember that rule 1.3 also doesn't permit discussion of plankton...
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.
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.
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.
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.
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.
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).
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.
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 Parts of it just look... too smooth!
Couldn't they do that with any object mapped by radar? Like, lets say, Venus?
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.
http://arxiv.org/abs/1601.03364
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.
This is a 'color' version using the CB3, MT1 and MT3 filters:
Going for the MEX VMC look?
Looks very nice.
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
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?
https://flic.kr/p/LboV6h
https://flic.kr/p/LboV6h by https://www.flickr.com/photos/10795027@N08/, on Flickr
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
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
That video of cloud dynamics is great, Ian!
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
Thanks fellas! 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
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.
AWESOME images IAN! I can only echo the great tribute of thanks of ngunn above.
My processed version of this observation is now up!
http://photojournal.jpl.nasa.gov/catalog/PIA21051
Jaw dropping!
This image stacking works well on Titan!
Way to totally trump me, Jason! Awesome work, sir. And is that hazes and/or fog I see hovering over Ladoga Lacus?
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.
Thanks for the links. 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.
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
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:
I think this is probably the best view of Kraken Mare to date.
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 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.
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:
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.
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
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 -
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.
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.
Refering to the circular feature: maybe impact should be considered too?
With the new year comes changes on Titan: just look at the size of the cloud bands girding the upper latitudes!
animation of clouds
https://twitter.com/kevinmgill/status/815718720014196736
More superb views of lakes and clouds today: https://saturnraw.jpl.nasa.gov/multimedia/images/raw/casJPGFullS98/N00277002.jpg
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/
https://flic.kr/p/TfbhNx
https://flic.kr/p/TfbhNx
https://flic.kr/p/Tfab3v
https://flic.kr/p/Tfab3v
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/.
Much of this work was done by UMSF moderator Juramike, who is quoted extensively in the Universe Today article.
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.
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".)
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?
Thanks Ralph and Mike for your courageous experimental study about the bubble phenomenon. Risky I guess with all these volatile hydrocarbons...
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.
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....)
Thanks for the informative replies.
I find myself wondering whether gravels entrained by a dense river would end up floating on top of a less-dense sea.
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!)
Thanks Mike. We're off on holiday today so this will be great in-flight reading.
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!
"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.
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!
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
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...
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
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/
Saturn’s moon Titan sports phantom hydrocarbon lakes
Three features that were filled with liquid appear to have dried up
https://www.sciencenews.org/article/saturn-moon-titan-hydrocarbon-lakes
https://www.space.com/saturn-moon-titan-phantom-lakes-caves.html being the lakes could seep into porous https://www.popularmechanics.com/space/solar-system/a27165376/cassini-found-that-titan-has-lakes-of-methane-resting-on-giant-mesas/ implying possible caves, aquifers, cenotes...
Short new paper out in JGR (Open Access) summarizing and contextualizing the bathymetry results from Cassini. Was quite pleased with the summary figure
http://doi.org/10.1029/2020JE006786
Those are some fantastically interesting results, Ralph! While the depths exceeded Cassini's ability to probe fully, that work characterizes the titanian seas quite nicely in terms of (much of the) depth and composition. These are the results that ones hopes for when the mission flies!
Fascinating that ethane is being framed as a salt analogue in the seas. The chemistry of Titan is astonishingly alien.
I notice that for the three northern tracks, where ethane abundance is estimated, it increases from north to south. With three data points, there's a 33% probability of getting them in order by random, so that's very far from significance, but I wonder if it means that methane could be entering from the north on a systematic basis. E.g., higher rainfall rates near the pole. I'm thinking of this by analogy with the salinity in the San Francisco Bay, where places near to where rivers flow in have lower salinity and the salinity is highest near the Golden Gate.
Of course, this is reading a lot into a little data.
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)