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Lakes in the limelight, the 2013 image bonanza continues
Juramike
post Apr 28 2017, 06:05 AM
Post #151


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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!)


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ngunn
post Apr 28 2017, 07:49 AM
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Thanks Mike. smile.gif We're off on holiday today so this will be great in-flight reading.
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hendric
post May 3 2017, 03:20 PM
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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.


--------------------
Space Enthusiast Richard Hendricks
--
"The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke
Mother Nature is the final inspector of all quality.
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Juramike
post May 5 2017, 02:14 PM
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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!


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