Surface Chemistry of Titan Options

[ustrax]

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?

[tty]

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*

[Juramike]

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.

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

[nprev]

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.

[tty]

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.

[Mongo]

According to this pdf, The following substances would have accumulated to these global average depths over Titan's lifetime (assuming no recycling):

ethane - 300-600 m as liquid
acetylene - 100 m as solid
propane - 20 m as liquid
hydrogen cyanide - 20 m as solid
cyanoacetylene - 2 m as solid
cyanogen - 80 cm as solid
carbon dioxide - 2 cm as solid

Bill

[ngunn]

Brief comment - organic chemistry is definitely not my area - but given that metallic catalysts are likely to be in very short supply (with the interesting exception of big impacts) it must be worth considering what kinds of reaction might be possible without them. Two lines of thought:
1/ Which organic reactions happen exceptionally fast at 'normal' temperatures?
2/ Could Titan be making its own exotic catalysts - perhaps (charged?) nanoparticles of some kind? In Lightning?
Our terrestrial environment contains enough water to keep everything 'earthed/grounded' most of the time. On Titan this may not be so and there may be a lot more static charges floating around.

[Juramike]

ethane - 300-600 m as liquid
acetylene - 100 m as solid
propane - 20 m as liquid
hydrogen cyanide - 20 m as solid
cyanoacetylene - 2 m as solid
cyanogen - 80 cm as solid
carbon dioxide - 2 cm as solid

Thanks, Bill!



1) (20 points) Given the materials above plus common inorganic reagents, propose an efficient synthesis of chlorophyll.

Time limit: 4.5 billion years.

[belleraphon1]

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.

tty...

The water/ammonia bedrock is presumably the crust of a global sea. Impacts would not penetrate to the rocky center to liberate silicates and metals. Any black smokers would be at the bottom of that ocean. They would certainly add metals to the ocean. And the dark stains on Europa certainly hint that these internal oceans can be quite a brew of chemistry and elements.

Of course I do not believe we have confirmation yet regarding an internal ocean, but that is the presumption.

I agree that eons of meteors and dust should have ladled the surface goo-sphere with heavier elements ...
wonder how much over the course of 4.5 billion years?

Just looking at the ISS/VIMS/RADAR data products we can see that Titan's surface is certainly geomorphologically complex.

Craig

[belleraphon1]

Brief comment - organic chemistry is definitely not my area - but given that metallic catalysts are likely to be in very short supply (with the interesting exception of big impacts) it must be worth considering what kinds of reaction might be possible without them. Two lines of thought:
1/ Which organic reactions happen exceptionally fast at 'normal' temperatures?
2/ Could Titan be making its own exotic catalysts - perhaps (charged?) nanoparticles of some kind? In Lightning?
Our terrestrial environment contains enough water to keep everything 'earthed/grounded' most of the time. On Titan this may not be so and there may be a lot more static charges floating around.

All...

I mentioned the low temperatures and possible lack of heavy metals just as a precautionary to not let our terrestrial bias lead to wrong conclusions.....

I wish I could remember where I read this.... pretty sure it was an LPI abstract from pre-internet days.....
(Alex????)

The subject was the energetics and physics of PAHS and interstellar grains as they accumulate to make cometary material..... I could swear they mentioned that these molecues could liberate a great deal of energy at very low temperatures (40K - 70K range) during phase changes activated by UV, etc.,... I probably have this all garbled and just going on a recollection.

My point is that low temperatures do not a priori mean slow reaction rates......

Sure wish we could scoop up some of this Titan goop. But VERY GINGERLY.

Craig

[Juramike]

1/ Which organic reactions happen exceptionally fast at 'normal' temperatures?

The fastest reactions are metal-halogen exchanges. The second fastes are the acid/base reactions. I have seen deprotonations (acid base reactions ripping a hydrogen from a C-H bond) done at liquid nitrogen/ammonia temperatures, then followed by warming up to -20 C or so to allow the alkylation of the anion to occur.

In the synthetic laboratoy a typical temperature for running these reactions on a preparatory scale (with an overnight time frame) is -78 C (dry ice/acetone).

It would be interesting to dig into the chemical literature to see what kinds of reactions have been frozen up in a low temperature matrix for mechanistic study..then to see which of these might be possible on Titan given the likely mix of components and any bonus features (lightning, metal catalysts, etc.).

-Mike

[dvandorn]

You know, it's a lot of fun to talk about all the goo that ought to be present all over the surface of Titan. The real issue is, we need to reconcile that with what we actually see on the ground at the Huygens landing site -- a solid, goo-less, pebbled surface.

I'm not saying there isn't goo elsewhere. I'm just saying that the only place on the surface we have ever seen really close-up has none whatsoever. And it would appear to have been flooded by liquid many times in the past...

-the other Doug

[ustrax]

Speaking of Titan surface...
I made a sequence from the raw images.
Miserable quality and that damn Titanian frog...
But one question, there are some minimal differences in some shadowing, are they from Titan originally?

[Littlebit]

You know, it's a lot of fun to talk about all the goo that ought to be present all over the surface of Titan. The real issue is, we need to reconcile that with what we actually see on the ground at the Huygens landing site -- a solid, goo-less, pebbled surface.

I'm not saying there isn't goo elsewhere. I'm just saying that the only place on the surface we have ever seen really close-up has none whatsoever. And it would appear to have been flooded by liquid many times in the past...

-the other Doug

Water-ammonia bedrock remains a problem too: Huygens GCMS picked up increasing levels of methane, and some benzene, but no detectable ammonia. Since ammonia has a lower vapor pressure than benzene, if it is a primary constituent of the ground where huygens landed - we should have picked up on that.

Likewise, the vaper pressure of benzene is almost as high as the vapor pressure of water. Water is visible on the rocks, but so is 'something other than water.', and the refractive index is inconsistent with ammonia and water.

[ngunn]

One idea is that some process destroys ammonia pretty quickly at the surface. Here's a link I posted earlier:
http://www.cosis.net/abstracts/EGU2007/051...88baf6c8092ff18