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/i...1/N00286802.jpg

thanks! i wonder if this white blotchy streak in this image is a cloud formation, as it may be visible only at a narrow reflection angle, since its very dim in most other images, it also seems to have a dim complimentary dark streak (shadow?) next to (beneath?) it, which seems more apparent in images without the white streak..


Also, some of the recent Enceladus pics 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/casJPGFu...1/N00289114.jpg

EDIT: i posted to the wrong thread, so here is a stitch of a collection of those new Titan lakes snapshots
Click to view attachment

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-...drocarbon-lakes

More speculation being the lakes could seep into porous karst-like mesa terrain 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 wondered about that as well. I suspect they're using that term to mean it creates a denser fluid like saltwater in contrast to lower density freshwater.
The changes in visibility could akin to the vertical salt line in rivers and estuaries where freshwater meets sea water but doesn't mix much because of density differentials.
This makes sense, ethane mixed with methane will be significantly denser to pure methane.
If the flow is slow enough, lakes look something like a 1960s layered-cocktail e.g. Tequila Sunrise, with methane-ethane on the bottom and methane on the surface.
https://www.adn.com/science/article/mythbus...a/2013/02/05/#_

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.

Well, this is exactly the paradigm I suggested (based on even less data!) in my 2014 'Flushing of Ligeia' paper https://agupubs.onlinelibrary.wiley.com/doi...02/2014GL061133

The analogies I draw is with the Sea of Azov - Black Sea - Mediterranean gradient, with Azov much less salty than the Med. There's some backwash back and forth, causing mixing, but a net flow of freshwater from continental rainfall. Same story with the Baltic Sea and Atlantic.

An interesting paper postulating the shorelines of Titan’s seas are most consistent with flooded landscapes that subsequently have been eroded by waves, rather than a uniform erosional process or no coastal erosion. The paper is here https://www.science.org/doi/10.1126/sciadv.adn4192