Is Saturn's Titan Producing DNA in its Atmosphere Without Water? Experts Say "Yes"
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October 09, 2010

Is Saturn's Titan Producing DNA in its Atmosphere Without Water? Experts Say "Yes"

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Saturn's moon Titan has many of the components for life without liquid water. But the orange hydrocarbon haze that shrouds Saturn's largest moon could be creating the molecules that make up DNA without the help of water – an ingredient widely thought to be necessary for the molecules' formation according to a new study.

The researchers warn however that although Titan's atmosphere is creating these molecules, that doesn't mean that the molecules are combining to form life, But the finding could entice astrobiologists to consider a wider range of extrasolar planets as potential hosts for at least simple forms of organic life, the team of scientists from the US and France suggests.

The new findings also suggest that billions of years ago Earth's upper atmosphere – not just the so-called primordial soup on the surface – may have been the sources for these "prebiotic" molecules, amino acids and the so-called nucleotide bases that make up DNA.

"We're really starting to get a sense for what kind of chemistry an atmosphere is capable of" performing, says Sarah Hörst, a graduate student in planetary science at the University of Arizona, who led the research effort.

NASA's Cassini spacecraft, which has detected large molecules at altitudes of some 600 miles above Titan's surface. But the molecules are so far unidentified because of limitations to the craft's instruments. The Cassini research team replicated Titan's atmosphere in a large chamber at the temperatures present in the moon's upper atmosphere. To play the role of the sun's ultraviolet light hitting Titan's atmosphere, they used radio energy at a power level comparable to a modestly bright light bulb. The UV light is critical because it breaks up molecules such as molecular nitrogen or carbon monoxide in Titan's atmosphere, leaving the individual atoms to choose up different partners, forming new molecules.

The experiment yielded tiny aerosol particles. The team ran the particles through a sensitive mass spectrometer, which showed the chemical formulas for the molecules that made up the aerosols.Hörst then ran the formulas past a roster of molecules biologically important for life on Earth. She got 18 hits, including the four nucleotides whose combinations form an organism's genetic information encoded in DNA. It appears to be less important that water is present to form these molecules than it is for some form of oxygen to be present in the mix of ingredients, she concluded.

On Earth, oxygen early in the planet's pre-life history would come in the form of carbon dioxide and carbon monoxide from volcanic activity, as well as from water released by volcanism and through meteor and comet impacts. On Titan, the oxygen appears to be coming from Enceladus, an ice-bound  moon of Saturn in its own right because of icy geysers spewing into space from near its south pole. Some researchers think the geysers hint at a possible global subsurface sea and a potential habitat for life.

Last year, researchers showed how water molecules ejected as part of Enceladus's geysers can be carried great distances through the Saturn system, with some oxygen-bearing molecules finding their way to Titan.

Casey Kazan via NASA and csmonitor.com

Comments

"Saturn's moon Titan has many of the components for life without no liquid water." So then it has liquid water? Or does it ain't not got none?

No water = no life. The amazing and counter-intuitive properties of water are not to be dismissed at all. There is no substitute.

Keith caught the thing that stood out to me.

Then there's: "The researchers warn however that although Titan's atmosphere is creating these molecules..." Who is however, and why where the researchers warning him? Oh, wait, Mr. Kazan just forgot to put in a couple of commas.

But grammatical nitpicking aside...

Biologists have known for some time that the rule cited by hidflect is not necessarily 100% true -- though unlikely, life in water-free environments is possible, and one of the rules of physics is that whatever is not forbidden is required.

If water-free life is discovered on Titan, it could open up many more possibilities for finding life -- including sapient life, or at least signs of it -- on extrasolar planets.

DNA based life could be more advanced on Titan then on earth. There could be a food chain of complex organic molecules like on earth. they would be on the top of the chain, and conceiveably might be responsible for ufo's seen by astronauts like buzz during the landing on the moon.

This article needs proof reading.

Just why exactly is water required for life? Perhaps it makes it easier, but I see no proof that it is required.

That is one of the reasons I liked Babylon 5 so much. This scifi series had intelligent beings from other possible planets other that just earth like.

Has anyone considered that the DNA could be a drastically DIFFERENT form of DNA, methane - based instead of water - based ?
We need to start thinking outside the box when it comes to extra - terrestrial life.

I didn't see anything in the article to justify the "Experts Say Yes" part of the title. Seemed to me that the experts only held out the possibility.

Kris,

That's a good question. And, of course, we can't completely rule out life which does not require water. What we do know is that here on Earth, life can adapt to mindbogglingly extreme combinations of conditions. Whereas much of the life on Earth enjoys a lovely spring day, the cyanobacteria in Yellowstone's geysers and pools thrive at over 100C temperatures, in water with the PH of battery acid. The tube worms and archaea living near deep hydrothermal vents seem to do quite well at extremely high pressures and temperatures, without need of oxygen or sunlight. Life has adapted to existence in high concentrations of heavy metals, or temperatures of up to 122C (250F), or extreme salinity, extremes of pressure, or extremes of PH, both acidic and alkaline. Bacteria even live and produce inside of glaciers.

However, if you go to the Atacama desert, the driest desert in the world, some 50x drier than the Sahara, and scoop up a container of sand to have analyzed, you will find that it is as sterile as a surgeon's scalpel.

Our kind of life can adapt to all of the aforementioned extreme conditions, and more. But it apparently cannot adapt to an environment without water.

This may or may not apply to some completely different form of life. But it would have to be *very* different kind of life than ours. So different that we might have trouble recognizing it.

That said, Titan, with its lakes of liquid hydrocarbons, and methane existing in solid, liquid, and gaseous states, and solid water, albeit frozen as hard as quartz, is a *very* different environment for life to have evolved in. So it might just be possible.

But anyway, lack of water is about the only condition that the only kinds of life that we know about have not been able to adapt to.

"That is one of the reasons I liked Babylon 5 so much. This scifi series had intelligent beings from other possible planets other that just earth like."

Hey! Star Trek had ambulatory crystaline beings who considered shirt sleeve weather to be higher than what most of us use when we're in a big hurry to cook a frozen pizza. And who breathed some undisclosed, but thoroughly toxic-to-humans atmosphere. (I always got the impression it was hydrogen sulphide or something.)

It's just too bad they had such annoying voices and temperament.

http://images2.wikia.nocookie.net/__cb20070804035331/memoryalpha/en/images/e/e1/Tholian_pilot.jpg

you most certainly dont need oxygen or water for life, for all those asking the reason u need water is it acts as a solute so u can have other things such as organelles or dna. methane is commonly only used to substitute for water because of how many bonds it can have with hydrogen, among other things.

"you most certainly dont need oxygen or water for life"

Matt,

On Earth, it has been demonstrated that you don't need oxygen for life. In fact life has adapted to all the niches I mentioned in my post above, and more. And yet we haven't a single example of life adapting to the lack of water. This is not to say that it's not possible. But it would have to be a very different chemistry, indeed.

"for all those asking the reason u need water is it acts as a solute so u can have other things such as organelles or dna. methane is commonly only used to substitute for water because of how many bonds it can have with hydrogen, among other things."

Say what? Water is generally a solvent, not a solute. Regarding bonds with hydrogen, aren't you thinking about the carbon atom and not the methane molecule?

That said, all those hydrocarbons sloshing around in liquid form are grounds for excitement. If liquid water is *not* an absolute requirement for life, Titan is the perfect place to study.

It's just too bad that the Titan Saturn System Mission got cancelled due to lack of funds. It will likely be 30 years or more, if ever, before we do further investigation. Because the American public consistently sets the limit for space exploration at about a dollar a week, per capita.

-Steve

Water is crucial for any life that would even remotely resemble life as we know it on earth. Just because the right organic molecules are present in one place does not mean that such a complex macromolecule such as DNA could form. Water is the only reason DNA forms its double helix. Self assembly based on hydrophobic/hydrophilic interactions dictate its shape as well as the shape of a vast number of proteins that build life. And how do you expect life to evolve without plasma membranes to contain the complex reactions of life. Water is fundamental to the function of a lipid bilayer. At best without water, we might find chains of nucleotides or amino acids that don't take up any functional shape and are therefore useless as anything other than chemicals.

The universe is an estimated 13 or so billion years old. Life on earth is about what, 4 billion? A lot can happen in 13 billion years people. You only have to look up at the night sky to figure it out.

I think the key thing here is that water is required to create life AS WE KNOW IT. It does not necessarily follow that water is necessary to create life and we may or may not recognize what we discover as a lifeform we understand.

It was once believed that photosynthetic plants were among the earliest life forms on earth because sunlight was necessary to create food. That may be true, but research of fumaroles in the deep ocean have found chemosynthetic organisms that create food from sulfur emissions without the presence of light at all.

Mike.

The article is seriously miss-titled. To the point where it undermines the credibility of the author and the real science being uncovered. There is not a hint of 'DNA' being created in Titan's atmosphere. Its is interesting that the four basic nucleotides are being synthesized. However, as @Steve Bergman, points out that is a very very very long way from discovering a long chain helical DNA molecule. IMHO the article would be far more credible if the title was changed to "Have The Building Blocks of DNA Found in Titan's Atmosphere.

I have actually come up with my own theory (but someone else has probably thought of it before) that not all life needs water to be life. I think that all life on Earth needs water, but perhaps there is some other molecule for different planets that is required for life. After all, maybe these other planets have 'almost-life' forms that are continuously adapting to that planet's environment. If there is no water, then they are adapting to be life that doesn't need water to be so.

Agree with Emma. It's all about adaptation. Maybe no water..maybe no oxigen...but still LIFE!

your title is very misleading, a couple of nucleotides does not make DNA nor does some amino acids. fix it or continue to look stupid.

I won't go so far as to say that life can exist without water but niether will I go so far as to say that life can't exist without water. At first we thought that life was created by some ethereal being not long before we came into existence, turned out it was around over a billion years before we came into existence. Then we thought life could'nt possibly exist without sunlight. We were wrong about that as well. We thought life couold'nt exist in acid or tar or in the deep recesses of the earth. Dead wrong again! We even came to find that structures resembling the double helix could form from dust and plasma, replicate and pass on traits. It is quite possible that life cannot exist without water. But over the centuries we have been utterly surprised at some of the things we have found. Should they one day discover a form of life that does not fit our common understanding of what life is, I sertainly wouldn't be surprised.


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