Tropical Lakes On Saturn Moon Could Expand Options For Life

ananyo writes "Nestling among the dunes in the dry equatorial region of Saturn's moon Titan is what appears to be a hydrocarbon lake. The observation, by NASA's Cassini spacecraft, suggests that oases of liquid methane — which might be a crucible for life — lie beneath the moon's surface. Besides Earth, Titan is the only object in the Solar System to circulate liquids in a cycle of rain and evaporation, although on Titan the process is driven by methane rather than water. This cycle is expected to form liquid bodies near the moon's poles, but not at its dune-covered equator. Now scientists think they have found a tropical lake — some 60 kilometers long and 40 kilometers wide, and at least 1 meter deep — in Cassini observations made between 2004 and 2008. Because tropical lakes on Titan should evaporate over a period of just a few thousand years, the researchers argue that these ponds and lakes are being replenished by subsurface oases of liquid methane. That would expand the number of places on the moon where life could potentially originate."

Comments

Needless(?) to say, life found THERE would be...

[wisebabo]

Absolutely positively evidence that the universe was crawling with life!

It would mean life is not only not based on DNA (and thus couldn't be a result of cross-contamination with earth as has been suggested might be the case for any Maryian life we might come across), but wouldn't even be based on WATER! It would mean that perhaps anywhere there was a liquid at perhaps almost any temperature we should be on the lookout for life! (Liquid helium on Pluto? Molton magma in the earth's mantle?)

I read in the book "Life as we do not know it" that Titan could be the home to up to three(!) completely separate "Domains" (the authors term) of life. Water based (around some heated cryo-volcanoes perhaps), ammonia-water, and methane based.

Someday we'll send a manned mission to orbit Titan. Then using remote balloons(!) and boats(!) they'll be able to really investigate these possibilities. Until then, the time lag will make things difficult (but not impossible I hope).

Re:Any pics of lake?

[CSMoran]

Was it discovered using something besides imaging and spread radar, such as point radar?

Imaging of data gathered in a chronosynclastic infundibulum, AFAIK.

CHON is where it's at

[Pfhorrest]

AFAIK there's nothing to say that methane-based life couldn't also use DNA. Methane is still carbon and hydrogen. All living organisms on Earth are composed primarily of carbon, hydrogen, oxygen, and nitrogen (CHON), and the general presumption looking for life elsewhere in the universe is that places with high concentrations of those elements is a good place to look, because we know life can be built out of them. Hydrogen and carbon dioxide are interconvertible with methane and water very much like carbohydrates (such as methane) and oxygen are interconvertible with carbon dioxide and water; all these processes involve the, C, H, and O of CHON equally, and the former was actually quite common early in the history of life on Earth. It wasn't until photosynthetic organisms started using light to convert CO2 and H20 into O2 and various CH's that the now-free O2 and CH4 reacted to become more of the H2O and CO2 that now cover our planet. (And then the O2 kept piling up and almost killed it all until some enterprising organisms started combusting it with those other CH's into more H20 and CO2).

TL:DR; methane really isn't all that weird an environment to find life much like we know it. Molten silicon and iron, on the other hand, or liquid helium, that would require some as-yet-unknown chemistry).

Re:CHON is where it's at

[codewarren]

Extreme cold, on the other hand, does reduce the odds of finding life. Not because things can't live in cold climate, but because evolution is ultimately a chemical process, and all chemical processes are retarded by cold. It took life on earth billions of years to evolve in a temperate climate. In a gigantic freezer, it could be expected to take much much longer.

Re:CHON is where it's at

[grep_rocks]

It takes more than just having the right elements to create life - water has some interesting chemical properties that methane lacks - such as it is one of the only chemicals which expands when it freezes, water is a polar molecule being slightly positive on one side and negative on the other, can form a large number of hydrogen bonds for its size, and especially relevant is that it is a fantastic solvent - all these properties are favorable for life, for example being a good solvent allows other molecules and ions to dissolve into water, allowing for lots of different types of chance chemical reactions to occur between different dissolved molecules - Methane is not as good a solvent as water, as it lacks polarity, however some people have proposed life working using poly-lipids as a substitute for proteins in non-polar liquids but because it is a poor solvent the chances of life working in a methane ocean seem less likely than water...

Re:CHON is where it's at

[myowntrueself]

One of the things that contributes to 'life as we know it' is the lipid bi-layer which forms cell membranes.

The lipid bi-layer is formed by molecules one end of which is hydrophobic and the other end of which is hydrophilic.

One has to wonder if similar analogous molecules exist for methane instead of water? Ie methane-phobic on one end and methane-philic on the other.

 

Re:CHON is where it's at

[Obfiscator]

Sure...the same lipids that are found in the phospholipid bilayer in our own cells. The hydrophilic end is methane-phobic, and the hydrophobic end is methane-philic. This would cause them to organize in the reverse direction so that the hydrocarbon tail is solvent-exposed. There seems to be some work on the subject, perhaps starting with Rand et al, Biochemistry, vol. 29, pp. 76--87 (1990), though it's really not my field so I'm not familiar with all the literature.

Rivers?

[MichaelSmith]

Maybe liquid methane flows from the poles to the equator and evaporates there. Then gaseous methane flows to the pole through the atmosphere and precipitates out.

Re:Rivers?

[ae1294]

Maybe liquid methane flows from the poles to the equator and evaporates there. Then gaseous methane flows to the pole through the atmosphere and precipitates out.

Nooooooooo GLOBAL WARMING has broken Titan!!!!

Re:Rivers?

[MichaelSmith]

Global warming stops the place from freezing solid. More greenhouse gasses could only improve the situation.

Re:Rivers?

[Quakeulf]

"Titan's grandtacular bean-eating contest"

Re:Rivers?

[MichaelSmith]

Its an interesting question. If you could find fossil oxidisers on Titan, you could run internal combustion engines on methane.

No Proof

[lixns21]

There is no proof that there is any life at all. The paper(http://www.sciencedirect.com/science/article/pii/S0019103510001053- login needed) that interpreted the data from the Cassini mission has been questioned by Chris McKay (NASA http://www.spacedaily.com/reports/Have_We_Discovered_Evidence_For_Life_On_Titan_999.html). The possibilities do NOT rule out life but comes out with other explanations that are more plausible.
1. The determination that there is a strong flux of hydrogen into the surface is mistaken. It will be interesting to see if other researchers, in trying to duplicate Strobel's results, reach the same conclusion.
2. There is a physical process that is transporting H2 from the upper atmosphere into the lower atmosphere. One possibility is adsorption onto the solid organic atmospheric haze particles which eventually fall to the ground. However this would be a flux of H2, and not a net loss of H2.
3. If the loss of hydrogen at the surface is correct, the non-biological explanation requires that there be some sort of surface catalyst, presently unknown, that can mediate the hydrogenation reaction at 95 K, the temperature of the Titan surface. That would be quite interesting and a startling find although not as startling as the presence of life.
4. The depletion of hydrogen, acetylene, and ethane, is due to a new type of liquid-methane based life form as predicted (Benner et al. 2004, McKay and Smith 2005, and Schulze-Makuch and Grinspoon 2005).

Does it have to be pure methane?

[jbeaupre]

Could it be a brew of organic compounds that would normally freeze, but with just enough methane to keep it liquid? The methane vapor pressure could be in equilibrium with the atmospheric methane. It'd also have to be some blend that doesn't want to slowly crystallize out the solute. So solubility would have to be high for the solutes.

An Earth equivalent would be honey. Liquid, water based, stable, doesn't dry out.

Chances are the authors have thought of this and rejected it. If someone could explain why, that'd be great.

Re:Does it have to be pure methane?

[lixns21]

Plausible but unlikely. Plausible since remnants of methane tend to form complex organic compounds but unlikely since if the entire composition was a single compound, the spectrographic analysis would have likely identified it! And honey does dry out! http://scienceline.org/2007/04/ask-westly-crystallizedhoney/

Helium rain

[arisvega]

Besides Earth, Titan is the only object in the Solar System to circulate liquids in a cycle of rain and evaporation

No, it is not.

Re:Helium rain

[arth1]

What about Venus ? I thought it rained on Venus, hot sulphuric acid, but still..

Yes and no. It rains sulphuric acid in the upper athmosphere (which is almost all carbon dioxide and so dense you can almost swim in it), but the rain never hits the ground.

Still, Venus is - by far - the planet that resembles Earth the most. Much more so than Mars.
Yes, it's more inhospitable too.

Re:Helium rain

[ShanghaiBill]

Still, Venus is - by far - the planet that resembles Earth the most. Much more so than Mars.
Yes, it's more inhospitable too.

The surface of Venus is inhospitable. But people could live in the atmosphere. The atmosphere of Venus is so dense, that a floating city filled with an Earth-like atmosphere of oxygen+nitrogen would have enough buoyancy to float. The upper atmosphere is much cooler than the surface. Sunlight is more than twice as bright as on Earth, so there would be plenty of energy.

Perhaps weather patterns have changed

[Viol8]

We know on earth deserts can form in a few thousand years so why not on Titan? Perhaps that lake is the remenant of something much larger that formed when that part of the moon was far wetter a few thousand years ago?

Re:The Slylandro

[Brucelet]

RTFS, dude. "Besides Earth" is right there next to gp's quote.

life but no civilization

[Papa Legba]

Implications of the fact that step one in building a technology base/civilization is the discovery of fire, which for a methane based life source is not going to go over so well. I can only assume that development is going to be stunted in an enviroment where a strike anywhere match is the same equivilant as the deathstars laser.

Re:life but no civilization

[ceoyoyo]

On Titan you're surrounded by combustable fuel, but you have to go looking for oxidizer. On Earth, we're surrounded by oxidizer but have to go looking for fuel. As far as fire is concerned, it's the same thing.

Re:Since the boiling point of methane is...

[Rogerborg]

I'd love to think that right now on Titan some right-minded blob is telepathically ranting "But the melting point of dihydrogen monoxide is 273K! Nothing could live in such a hostile environment!"