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CraigS
10-08-2010, 05:04 PM
Hi All;
Following the SBS/BBC Doco on Titan last night, some interesting scientific issues/history were stirred up for me relating to the geological makeup and chemistry of the surface and atmosphere. Let me explain with some info from Wiki (for expedience):

"The Stratosphere of Titan is largely composed of nitrogen (98.4%), methane (1.4%) and hydrogen (0.1-0.2%); minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog ... With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan is viewed as analogous to the early Earth, although at a much lower temperature. The satellite has thus been cited as a possible host for microbial extraterrestrial life or, at least, as a prebiotic environment rich in complex organic chemistry."

Life on Titan ? Perhaps, .. maybe not, also.
But the interesting issue for me is the presence of the surface hydrocarbons.

"Based on Cassini observations, scientists announced "definitive evidence" of lakes filled with methane on Saturn's moon Titan" in January 2007.... In June 2008, the Visual and Infrared Mapping Spectrometer on Cassini confirmed the presence of liquid ethane, beyond doubt, in Ontario Lacus".

"Many astronomers have suggested that the ultimate origin for the methane in Titan's atmosphere is from within Titan itself, released via eruptions from cryovolcanoes. A possible biological origin for the methane has not been discounted."

So, back in the 70’s a competing theory to the biological fossil origins of our beloved petroleum, was being proposed by Thomas Gold, an Austrian-born astrophysicist, a professor of astronomy at Cornell University. The theory was called the ‘Abiogenic origins of Petroleum’. Gold is now somewhat discredited for this, but he did do a lot of heavy, legitimate science behind this theory. Some of his other theories got a little wild towards the end of his life (in 2004) and some argue that he may have falsified evidence.

“The abiogenic hypothesis argues that petroleum was formed from deep carbon deposits, perhaps dating to the formation of the Earth. The presence of methane on Saturn's moon, Titan, is cited as evidence supporting the formation of hydrocarbons without biology. (ie: fossils). Supporters of the abiogenic hypothesis suggest that a great deal more petroleum exists on Earth than commonly thought, and that petroleum may originate from carbon-bearing fluids that migrate upward from the mantle.

I should add that:

“Although the abiogenic hypothesis was accepted by some geologists in the former Soviet Union, most geologists now consider the abiogenic formation of petroleum scientifically unsupported. Although evidence exists for abiogenic formation of methane and hydrocarbon gases within the Earth, studies indicate they are not produced in commercially significant quantities (i.e. a median abiogenic hydrocarbon content in extracted hydrocarbon gases of 0.02%). The abiogenic origin of petroleum has also recently been reviewed in detail by some scientists, who raise a number of objections, including that there is no direct evidence to date of abiogenic petroleum (liquid crude oil and long-chain hydrocarbon compounds)”,

.. although abiogenesis does result in compounds very close to what we call ‘petroleum’.

Whilst I’m certainly not a devotee of Abiogenetic origins of petroleum or of Gold, it is interesting to note the unfolding similarities between this scientifically based theory, and the makeup of Titan.

This post is only discussion/awareness raising purposes only .. I’m not religious about any particular theory about the origins of anything. - The program just made me think a bit more.

Cheers to all. :)

renormalised
10-08-2010, 06:12 PM
Yes, it's a very interesting topic to have brought up and I will think it's going to provoke some discussion amongst scientists for quite some time.

The atmospheric chemists and the geologists are going to be pouring over the data and the theory and going through old assumptions with a fine tooth comb.

With Titan though, things are going to be moving a darn side slower than they would on Earth because of the cold temps. The main driving forces for creating the hydrocarbons on Titan would be production of the methane/ethane and such from geological processes and the hydrocarbons through photodissociation of methane and such at altitude by UV light and then recombination through chemical reactions into long and short chain hydrocarbons. However, most of these hydrocarbons would have to sink rather quickly because the UV would also break them up as well if they remained exposed to the light for too long. Much of that orange haze in Titan's atmosphere would be organics and busted up methane, ethane and such. Basically a whole lot of smog:)

CraigS
10-08-2010, 07:16 PM
Looks like "the structure of the orange haze is not currently known, but they are believed to be tholins (tar-like organic precipitates), and may form the basis for the formation of more complex molecules, such as polycyclic aromatic hydrocarbons."
Also, it seems that there may be some heat in the 'hotbed' regions and that this heat may be from radioactive decay in the mantle, or tides induced by Saturn's gravity (bit like Enceladeus).

All sounds like a mix of all the right stuff to stake a claim there, to me !!

With all the leap-frog excitement over the chance of pre-biotic life, I have a feeling that the real message on the formation of what clearly won't be 'fossil' fuels may be overlooked. I guess we'll see.

Fascinating !!

Cheers

renormalised
10-08-2010, 07:41 PM
Geez, just what we need. Another rush for oil!!!!:):P

renormalised
10-08-2010, 07:43 PM
Those hotbed regions are probably akin to what we have on Earth as mantle plumes and magma chambers. Except in this case, it's ammonia-water clathrate and whatever else is mixed in with it. It would be amazing to watch it erupt.

CraigS
10-08-2010, 07:51 PM
Maybe you can watch it:
"Cassini detected methane emissions from one suspected cryovolcano, and volcanism is now believed to be a significant source of the methane in the atmosphere."

Might go snooping on the Cassini site to see what I can find ... (its a brilliant site! ... one of my favs).
:)
PS: I won't ask what 'clathrate' is ... sounds nasty !!

renormalised
10-08-2010, 08:45 PM
A clathrate (http://en.wikipedia.org/wiki/Clathrate_hydrate) is a mixture of water and a volatile gas, like methane, ammonia etc. They form ices where the water molecules in the ice trap molecules of the gases. The water molecules act like a cage, trapping the gas molecules inside a lattice of the water molecules.

You get a lot of methane clathrates on the ocean floor. Actually there's a significant amount of methane gas trapped in these clathrates and it's a potential fuel/energy source. It's also potentially hazardous to the climate if these things start to melt, and it doesn't take much to start the melting. They've had quite a few methane belches in the Gulf of Mexico over the years. Some have sunk ships. The most vulnerable clathrate deposits are those lying in shallow shelf seas (like the Gulf). If they sublimate, we could be in for some intense action later on so far as global warming is concerned. Methane is something like 25-40 times more effective a greenhouse gas than CO2.

CraigS
10-08-2010, 09:49 PM
Interesting. I've read about these things and their effects.

Getting back to Titan, whilst I'd prefer to stay on the hydrocarbon/fuel tack, a 'little' diversion: Abiogenesis is the study of how life can arise from inanimate matter. Some say the chances of DNA occurring from pre-biotic chemicals are slight (& obviously never been done in the lab, either). But the chances of DNA assembling itself into self replicating proteins is even more remote, (given the specificity of 'coding' of information contained within DNA). It may be remote, but it is possible that a single chance occurrence may have happened in a single place, somewhere in the Universe.

Given the sheer size and dimensions we talk about in Astronomy, I'm starting to wonder whether it may be entirely possible, and perhaps even realistic, that this may be the way, it may have actually happened. (And the corollary to this one might also be that Earth may be that single, one place).

I'm talking purely statistically, here and yes, I'm talking about the probability of a 'fluke'.

I also recognise that this is contrary to the Standard Cosmo Model ..ie: isotropic, homogeneous, 'no special places', etc but I think this topic may fall out of the model's scope anyway. I wonder whether anyone has ever actually tried to calculate this (given its counter-intuitiveness - apart from the 'Drake Equation', that is). I've never read anything where anyone has looked at this side of the coin - its usually the other side, which I think everyone knows about.

Maybe I've been reading too much of that other thread today, huh?

Interesting.

Cheers
PS: Please - I respect all beliefs and I'm trying to just get a snapshot of the purely scientific perspective, here.

CraigS
11-08-2010, 08:05 AM
PPS: I know its a bit limiting to think of the Origin of Life in this way but it does help as a levelling tool for discussion forums.

The size of the numbers in this calculation are truly enormous.

I was recently reading Leonard Susskind's book:
"The Black Hole War: My battle with Stephen Hawking to make the world safe for quantum mechanics" and he wrote a good chapter:

"A note About Big Numbers and Small Numbers":
a quote:

"The human brain was not constructed to visualise numbers much bigger than 100 or smaller than 1/100, but we can train ourselves to do better."

Cool dude, is Leonard !! (For a theorist, that is ... I won't say 'mathematician' ... Steven might be watching).
:)

CraigS
11-08-2010, 09:15 AM
Oh yes ...

another quote ..(I'm on a roll) ...

""The suggestion that petroleum might have arisen from some transformation of squashed fish or biological detritus is surely the silliest notion to have been entertained by substantial numbers of persons over an extended period of time." Fred Hoyle, 1982."

Fred and Thomas Gold were two of the 'three amigos' of Cosmology, Astrophysics and Mathematics (post WWII).
Hermann Bondi was the other one.

Classic stuff !!

Cheers