The bulk of the liquid in the lakes on Titan is going to be a methane/ethane combination, but a lot of polymeric organic material is going to have been washed in from the terrain, as well as blown in from the dunes. (The lakes would be a dune trap). That means ice-silt and tholin-coated ice silt.

The higher-order organic polymers may act as a surfactant to coat the ice particles. I would hazard that the hydrophilic functionalities of the polymer subunits would side with the ice particle surface and the hydrophobic parts of the polymer would face the methane solvent. This would allow some really gnarly emulsions to set up.

A cross-section of a lake on Titan would look like a classic "nightmare extraction" sitting in a sep funnel in an organic chemistry laboratory. There would be a foamy goo or scum component floating on the surface, the methane/ethane layer as solvent possibly with low density organic shmeggums floating about, then a denser loose gelatinous organic polymer/solvent component full of organic yukkies (please excuse the med chem. technical jargon), then a more dense portion of organic polymer/organic solvent/water emulsion, and finally a water-ice silt bottom.

Water (ice) and organics are immiscible. But hexanes and acetonitrile (CH3CN) are also immiscible. By analogy, methane should also be immiscible with CH3CN (which would be a solid at Titan’s temperature, but a lower density component than ice). This should make for yet another fun emulsion possibility. [I’ve seen waaaaay too many ugly emulsions in sep funnels with “simple” organic components.]

With the complex organic chemistry at Titan, there is a very real possiblitiy of multiple layers of emulsions combined with an organic scum layer at the surface.

I’m not sure how any of this would affect specular reflections or even radar penetration. The surface would not look like the pretty foam of a bubble batch but more like the curd on overcooked pea soup.. Would certain layers reflect radar better than others? Can you get specular reflection when there are bubbles or “floaters” on the surface? What if the “floaters” are soft low density organics? How do organic emulsion blobs reflect radar?

The patterns we are seeing in the lower parts of the lakes may be channels in the goopy lower emulsion layers (think of the orange crud at the bottom of scummy ponds). I could imagine a scenario when higher density organic goo flows into the lakes and carves a path through the less dense emulsion. The real “bottoms” of the lakes may lie under meters of organic emulsion.

Lakes on Titan may resemble more of an open pit hazmat toxic waste dump (although I still like to think of it as “a pristine prebiotic environment”).


-Mike

Can't claim for a moment to have understood much of the science in that post jura, but with the references to "organic scum" and "overcooked pea soup curd" it's given me - possibly for the first time - a real and vivid mental picture of what a Titanian lake might look like, so thank you.

Yes, a useful post, thanks. I had been wondering along these lines too. Seas of shimmering clear liquid are very enticing to imagine but probably wide of the mark. The scale of our ignorance just seems to expand the more we see . .

Titan's tar tarns revealed.

The real question I have (perhaps already addressed) is whether the liquid in the lakes solidifies with the changing of the seasons, or only evaporates. It's a difference in erosional analogies of rain eroding ice or rain eroding rock...

Yes indeed, a terrific post, Juramike. I suspected that we might be underestimating the chemical complexity of Titan's lakes; your post answered al lot of questions (or at least articulated some excellent hypotheses to explain many of Cassini's observations, or lack thereof in the case of specular reflections...)

It sort of looks like Earth; it sort of even feels like Earth in some weird ways...but it ain't Earth!!!

MMMMMmmm "creme brulee crust and scummy pea soup!"

Hmm...In fact, how much evaporation actually occurs? Given the "scum scenario" Juramike described, I wonder if the anticipated methane monsoons can actually occur from lake evaporation; seems like most of the CH4 should be bound or trapped in some way.

"...Lakes on Titan may resemble more of an open pit hazmat toxic waste dump..."

Remind me to NOT join the Titan colony Polar Bear Club!

"[...] although I still like to think of it as “a pristine prebiotic environment”."

You've been writing too many proposals

Great post juramike! Really visual and...smelly...

According to Lebreton's oppinion its not only the lakes but also the surface that "must be covered with thick layer of organic goo.
Something that may resemble a polluted area (an icy coast) on Earth after a black-wave.”
One thing that makes me scratch my head is what is the process that makes possible for that "gelatinous" stuff to carve channels?...

I imagine that when fresh rain falls it is really very runny, with just a little suspended smust, looking a bit like well-diluted indian ink. Flowing across the surface it would get progressively dirtier and, especially in any rapids, foamy. I doubt if anyone is yet in a position to speculate on how long any such foam would persist, but I would expect both foam and sediment to decrease gradually after reaching the lake, leaving a dark emulsion. A coating continuous and persistent enough to seriously inhibit evaporation seems unlikely to me (I can't justify that - I suppose it could form a paint-like skin) but in any case there seems to be more than enough total lake area now to supply the proposed methane cycle. And with all that wet ground as well - -

It looks to me as if the narrow sinuous erosion channels continue into the deepest parts of some lakes, indicating that fairly runny stuff is present even in the later stages of drying out. This could be episodic (nocturnal?) new precipitation or a runny fraction may percolate out of the dirty deposits further upstream, even as they dry from the top down, rather as seawater can sometimes be seen trickling out of sandbanks at low tide.

Anyhow, clothes-peg for the nose definitely required, and NO SWIMMING.

Thanks ngunn.

Here's an interesting pdf, I don't know if someone made reference to it already...

Thanks Ustrax! That one's a real peach. Looks like the scientific literature is acquiring some interesting new vocabulary - and more may be required as the complexity of Titan unfolds. Still, they're not hard words to make up. Let's see now - spludge, flimp, thlupp, turj, frilth, glume, crusp, jellink, blooze . . .

And there's an obvious abbreviation for 'Polar goo'.

Another question...
In a crop from this image it looks to me that we can distinguish the level the liquid filling the lake can reach.
For my untrained eye it looks like (sorry for the sketch's quality...) we can see the bottom of the lake and the line marking the maximum height of the filling.
If this is correct is it possible to calculate how deep can it be?

OK this is difficult because I can't post annotated images but here goes. My guess is that the landward edge of your boxes does indeed mark the current shoreline. I'm counting your boxes from left to right 1 to 13. Now as regards the outer edge of the boxes - I think that from box 6 to box 11 your line follows a currently submerged drainage channel. At about box 12 the channel continues a bit to the right of your line, tracing a meandering course which continues all the way to the top of your crop, and beyond. This submerged channel, if that's what it is, cannot be deeper than a few 10s of metres (for 'clean' organic liquid). If the lake contains significant amounts of ice or other polar molecules in suspension then these features could be a whole lot shallower. That's my (tentative) view at the moment.

As the methane river flows downhill, any other organics would remain shaken into a suspension. Nearer to the lake, some of the organic phases may seperate and settle out according to density. It would probably not be a "clean" separation, more of different emulsion phases seperating out.

An analogy would be vinegar and olive oil salad dressing after it has had time to settle out.

The heavier emulsion phases (or even denser pure solvents) would slowly drop and creep their way to the lowest level of the lake bottom. They would carve a path through any gelatinous goo on the bottom of the lake. Saltier water forms such currents in Earth's ocean basins. The diffence on Titan would be that the fluffy gloopy gelatinous stuff on the lake bottom would be shoved aside by the heavier phase currents and the resulting paths would look like underwater streams when viewed by radar.

Back to the salad dressing analogy, if you had a big bucket of italian dressing that had partially separated out, then dumped in the separated vinegar and olive oil salad dressing, you should see the vinegar phase plunk to the bottom and shuffle the stuff around at the interface.

[I have not yet tried this, but it's lunch time here, and this is making me hungry....]

-Mike

Good interpretation ngunn, I hadn't seen those chanells...
I wish there were someone with ability to do some renderings on this...

I wouldn't expect phase separation - benzene, acetylene and ethane are infinitely soluble in methane. Expect the mixture to behave more like water/sugar/glycol mixtures - whether the mixture is runny or thick oil-syrupy would depend upon the methane content. I think the evidence of rivers and streambeds implies the stuff remains quite runny; which also explains how the lakes form. The heavier organics dissolved in methane would limit re-evaporation of the methane (boiling point depression). The atmospheric methane is more likely evaporated from areas near the equator, directly from the 'soil' than the polar lakes (unless there is geothermal heating). This is what appeared to have happen when Huygens heated the ground about her.

The composition of the dunes remains problematic: The refractive index and thermal inertia are inconsistent with water. Likewise organic 'dirtballs' are inconsistent with both methane solvation and a dune formation: Light organics are waxy. Solid 'tholins' remain hypothetical, and they would likely be very black, not yellow to red.

This would imply that there are never lakes at the southern pole, since there is less now (only one?). However, there is no indication that the seasons don't completely flip over in half a Titan's year time and hence the south will experience similar precipitation levels in this case. Or there must be massive transport towards the equator somehow or maybe it all seeps into the ground...

Brilliant thread folks. Goo-ological cycles, gunk thermokarsts, crusty pie floater lakes and the rest - welcome to the Toxic Treacle Terrain of Titan, please remember to wipe your boots at the door.

I totally agree at higher flow rates. The stuff flows as a liquid. It's the polymeric stuff that would act as an emulsifying agent and trap vesicles of solvent. This emulsion layer would have a slightly higher density than the free flowing liquid. When the flow rate drops, and some of the vesicles have time to "pop", the remaining emulsion becomes even more dense and then the layers may partially separate out.

Perhaps a better analogy would be Jell-o 123. When it begins to set up, the layers partially seperate out.

It does not take much polymeric material to make an emulsion. Only a trace would be needed to cause a clear methane stream to form a gloopy layer creeping along the bottom.

[In the organic laboratory, one technique to clear an emulsion when doing an organic/aqueous separation is to filter the whole mess through a fine filtering agent - like Celite. The semi-soluble offending emulsifying polymeric mixture is filtered off, and the phases can more easily separate. I imagine a Titanian stream or lake being thousands of times more complex than the most ugly laboratory extraction.]

-Mike

All...

agree this is a fascinating thread.

I am not a chemist, and correct me if I am wrong, but seems like many of these analogies are being taken from chem labs at terrestrial room temperatures. What happens to these materials at the cryogenic temperatures on Titan?

Craig

I'm not a chemist either but perhaps the room-temperature behaviour of long organic molecules is rather similar to the low temperature behaviour of shorter ones.

That's a really good question.

I would guess that as you cool things down, that the viscosity would go up. I would also guess that the "vesicle popping" action would also decrease. So a yukky emulsion slow-to-separate out at room temperature would become an intractable mess at really low temperatures.

In addition, many of the organic species: ethylene (m.p. 1 ATM 104K), acetylene (m.p. 1 ATM 189 K), methanol (m.p. 1 ATM 176 K), acetonitrile (m.p. 1 ATM 225 K) would be trying to freeze out at Titan's low temperature (93 K?). I'm not sure what the solubility would be in methane at such a low temperature. I could imagine little blobs of acetylene coming out of solution.

A funsy experiment might be to try to simulate the Titan environment in a chemical laboratory using heptane at -78 C (195 K) with a dry ice/acetone bath. You might be able to use heptane, bits of acetonitrile and added organic polymer gookies to see how an emulsion behaves at low temperatures.

[NOTE: This sounded so fun and tempting, I just did it myself. I used heptane, then added some acetonitrile and methanol then added a pinch of non-halogenated organic waste. A solid froze out (probably acetonitrile) and multiple hazy layers formed above the interface in the mess.]

The better experiment would be to find a way to easily hold a 90 K environment and condense in methane and ethane gases and trace organic emulsificants and see how the whole beast behaves.

-Mike

Wow...we have a no-kidding organic chemist in the house!!! Fascinating stuff, Juramike.

What sorts of atmospheric interactions might we expect under these conditions, if any, @ 1.5 bar? I assume that gaseous nitrogen is even more passive @ 90K...how about the organic constituents?

Nitrogen liquifies at 78K if I remember rightly. So why not nitrogen clouds at altitude and nitrogen showers that evaporate before reaching the ground?

This is fascinating stuff. Trying to figure out the normal case makes me think about how varied these kinds of things are on Earth, and how varied they might be on Titan.

I've seen beaches where foam in the surf can be seen in some places but not others, just meters apart. (This foam, I suspect, is some form of human pollutant, but I'm not sure of that.)

Think about how soil varies across the face of Earth. Sandiness, wetness, color...

I think about how different individual rivers I've seen have looked from one another, from crystalline waters in North Florida to the muddy Amazon, and even the color "collision" where the Monongahela and Allegheny meet in Pittsburgh.

Earth probably out-trumps even Titan in diversity, but I suspect that whatever our first splashdown lander sees, the second one will probably see something different.

In the meantime, great perspectives, Juramike. Look out for open flames while you do these Titan-simulation experiments.

Mike, I really hope you have a kid who can take advantage of you and make this his/her Science Fair project! (If you don't have one, borrow one.)

Can you post a photo?

--Emily

Yikes! I'll put out my cigar now...

Mike...

be careful in your lab. I may have two grandsons on loan to you in a few years.

Read the abstract on the Titan Goo-Sphere and found it fascinating. But the bottom line is that we really do not know the long term or macro-scale behaviour of any of these materials at Titan temperatures.

Which makes this world all the more fascinating. I hate to say it, but I half expected to find Titan a cratered planet (er... moon) with a thick atmosphere and a landscape dotted with arc-lakes. I could imagine a hike to the central seas over ejecta blankets of ice. Not much happening between the occassional atmospheric collapse.

BUT... now we see a world sculpted by cryovolcanics, some craters (but this is no Ganymede), enough erosion to seed dunes fields big enough to see from Earth, possible mountain chains, an honest-to- goodness methanological cycle, signs that seasonal changes are immiment, and we can watch for them....
and now, on the smaller scale, the details of organic chemistry awash in methane/ethane/water/ammonia
reactions on gigayear timescales.

Whoa!!!!!!

What mysteries lurk through the cryocrusts of Titan?

Craig

Well actually.... Tokano et al. predict a liquid methane-nitrogen cloud in Titan's lower troposphere based on Huygens data.

Titan makes chemistry fun!

Fascinating as these lakes are, it's worth remembering that the swathes of radar coverage are a small fraction of the north polar region - there could still be small sea next to this Lakeland...

Hmmm...I NEED a Titan orbiter. ...Preferably with a thirty-year lifespan.

Andy

Sorry Mike, I hadn't seen your answer...
You can really turn it into something visual...
Could the channels in the image that ngunn made reference to be the result of the paths you talk about opened by the heavier emulsion phases?
I have to look at the whole image again to see where they start...

I think it's worth bearing in mind that the gradients here are probably tiny. For that reason I favour a liquid/atmosphere interface (with plenty of density contrast) to produce the flow that made these channels.

Glad too see AndyG urging for a super-long-lived Titan orbiter. I think that was the subject of my first few posts on UMSF.

I don't know if this might be useful to you but I made it to help me differencing the darker areas,I tried to attach my original here but it was to large and in this version what I mean gets a bit lost...
They seem to concentrate closer to the shores from where the channels seem to be deriving from.
Does this go along with the idea of this heavier elements coming down from a higher point and diving under lighter ones?

EDITED: ngunn...if you are patient enough to wait for 2020-2025...there will be a proposal for a Titan dedicated mission with balloons and other cool stuff...

I agree, but only because it has biology. Take DNA out of the reckoning and Titan might well come out on top.



Maybe they should add submarines - and robotic pot-holers.

By what I've been told by one of the team members that will present the proposal a lot of the huge amount of work being done towards that will be imagining new technologies so...who knows?...

From the "Titan lakes revealed" thread




[From article]: "Long-term photochemistry can produce kilometer-thick deposits of acetylene over 8% of Titans surface".

Wow. That's a huge implication

Acetylene is an excellent building block for really complex organic chemistry. ["It takes Alkynes to build a world" - seen on a bumper sticker.] A good synthetic chemist should be able to propose a synthetic route to anything n given acetylene and free choice of inorganic reagents. (Hmmm, this will make a very nice candidate interview question...)

While the photochemical processes in the atmosphere are very cool, the surface organic chemistry would be beyond fantastic.

Small, catalytic amounts of transition metals in low valent states [especially Co, Rh, Ir, Pd, and Pt] would be able to zip together acetylenes to either cyclize or polymerize to make a fascinating assortment of aromatics and heterocycles. These could also incorporate CO, CN, and halogen functionalities that could allow even futher cross reactivity. The reducing atmosphere of Titan should keep these metals naturally in the low valent state. The only issue would be the low temperature on Titan. In the synthetic laboratory, higher temperatures (typically we use 90 C, 360 K) are used to help kick out the bound ligands to the metal center and push along the catalytic cycle. Could this happen at lower temperatures, given enough time?

Imagine an acetylene glacier creeping along until it uncovers a Pd deposit, initiating a slow cataytic cascade that converts the entire glacier into a polyaromatic polymer.

What kinds of surface molecules could be made given water, ammonia, HCN, and acetylene, and trace amounts of metal catalysts? (short answer: anything)

What kinds of organic/organometallic chemistry can occur deeper in Titan, with different solvents (water-ammonia) and different types of material being deposited out?

Could the surface/near surface chemistry help explain the spectroscopic properties of material observed on Titan's surface?

There are some seriously cool (pun intended) organic chemistry experiments to be examined.


Skip the rain forest, the surface of Titan looks like a great place to search for the next cure for cancer.
[Possible new justification for a future mission?]

-Mike

Precious...just precious to read your words...

Here's Huygens' surface spectrum it might get useful.
From here.

Why and how?

It probably is sometimes, but foam forms in unpolluted waters as well. Then it is usually formed by organics from phytoplankton broken up by wave action.

I'm guessing the really interesting molecules would be the non-volatiles. There might be a whole host of molecules that are discrete (non-polymeric) but that are too heavy to fly.

These would include complex multifunctionalized organic molecules, as well as really exotic organometallic complexes.

I was blown away when I read that phenylalanine can be generated from spark tholin. After that, I figure pretty much anything is possible.

I would honestly not be totally suprised if some of the pharmaceutical products currently on the market are actually present in extremely trace amounts on the Titanian surface. With enough acetylene, organic precusors, catalytic metals, solvents, and a little thermal action, the Titanian surface should be the solar systems biggest combinatorial chemistry experiment. "Prego - it's in there."

Biology may rule Earth, but Organic Chemistry rules Titan.

-Mike

Knowing that Titan is still active in its interior providing heat, is it out of question to think about something of this kind to live on the planets surface and/or lakes where there's no lack of methane and hydrogen?...

All....

once again have to keep in mind the surface conditions. Besides the low temperature, the surface "bedrock"
is presumably a water/ammonia ice mixture with not too many heavy metals. This overlies an ocean of water/ammonia with unkown trace constiuents and then a rocky center and core.

My point is that most of the heavy metals may be sequestered in that rocky core with no contact to the surface..... unless dissolved in that ocean and brought to the surface through cryovolcanism. Or delivered to the surface by meteors and dust.

One thing we do know for sure is that the surface that is being revealed to us is certanly complex.

Craig

Or this... http://www.funkyscience.net/documents/titanpaper.pdf "Biologically Enhanced Energy and Carbon Cycling on Titan"?

Craig

Funky!
"life on Titan could involve huge (by Earth
standards) and very slowly metabolizing cells"
Just imagine a huge colony of those, like coral reefs on Earth...
What could act as chitin on Titan? Some natural plastic-like polymer?

Note that one theory of how life originally evolved on Earth considers that natural selection may have worked at a prebiotic level to select for "sticky" organic molecules that could stabilize the "soil" against (water) erosion.
Something similar might well be going on on Titan.

Some people would probably consider that the ultimate in vulgarity a *plastic covered landscape*

A really good point.

There may be ways to get deep stuff (metallic minerals) up to the surface.

Through cryovolcanism (which there seems to be more and more evidence for multiple flows on Titan). Perhaps a Kimberlite pipe analog also exists on Titan.

Then there are putative "cryothermal" vents. The black smokers on Earth are incredibly metal rich, with metal sulfides plooping out of aqueous solution in the undersea vents.

The fact that Titan has a nice thick atmosphere makes sure that meteoric material will be delivered to the surface (just like in Illinois this week), although I'm ignorant if the lower layers of the atmosphere would cause the meteors to fragment into catalytically useful pieces or remain as big chunks. Catalytically useful chunks would have a better surface area to volume area, and smaller pieces would be better for faster dissolution or chemistry at the catalyst surface..

Wind transport of grains of material delivered onto the surface could make sure that any little bits on the surface get get somewhere.

It really only takes a tiny amount of catalytically active material to do the job. For example, in a laboratory setting, 0.5 mol% of a really active catalyst can get an easy tranformation done on a reasonable timescale (i.e. overnight).

-Mike

Large impacts, though rare, undoubtedly must have spread metals around the surface over time, perhaps even globally and perhaps as discrete melt droplets if a deposit got hit. There may have been frenetic local catalyzation events after such impacts.

With such a deep atmosphere micrometeorites would be slowed down very high and then very slowly sink to the surface as dust. A Tunguska-type body would also explode quite high, and the resulting dust disperse widely.
In short there should be a constant slow trickle of more or less metallic dust onto the surface.

Terran "black smokers" contain large amounts of metals because the hot water has circulated through metal-rich basalt. I don't think there is likely to be any such metal-rich substrate close to the surface of Titan, except possibly near large impacts. At least on Earth large impact craters have associated short-lived hydrothermal systems. Something similar may operate on Titan, and possibly for longer time-periods since temperatures are lower and the ground almost certainly has much lower thermal conductivity than on Earth, i e heat dissipates more slowly.