Life on Titan?

Saturn's moon Titan has long been a place of interest to astrobiologists, primarily because of its apparent similarities to the early Earth at the time life first started. A thick atmosphere composed primarily of nitrogen and abundant organic molecules (the ingredients of life as we know it) are among the important similarities between these two otherwise dissimilar planetary bodies.

Scientists have considered it very unlikely that Titan hosts life today, primarily because it is so cold ( -289 degrees Fahrenheit, or -178 Celsius ) that the chemical reactions necessary for life would proceed too slowly. Yet previously published data, along with new discoveries about extreme organisms on Earth, raise the prospect that some habitable locales may indeed exist on Titan.

In a paper being presented at the Division for Planetary Sciences 2005 Meeting this week, a team of researchers from Southwest Research Institute ( SwRI ) and Washington State University say that several key requirements for life now appear to be present on Titan, including liquid reservoirs, organic molecules and ample energy sources.

Methane clouds and surface characteristics strongly imply the presence of an active global methane cycle analogous to Earth's hydrological cycle. It is unknown whether life can exist in liquid methane, although some such chemical schemes have been postulated. Further, abundant hints of ice volcanism suggest that reservoirs of liquid water mixed with ammonia may exist close to the surface.

"One promising location for habitability may be hot springs in contact with hydrocarbon reservoirs," says lead author David H. Grinspoon, a staff scientist in the SwRI Space Science and Engineering Division. "There is no shortage of energy sources [food] because energy-rich hydrocarbons are constantly being manufactured in the upper atmosphere, by the action of sunlight on methane, and falling to the surface."

In particular, the team suggests that acetylene, which is abundant, could be used by organisms, in reaction with hydrogen gas, to release vast amounts of energy that could be used to power metabolism. Such a biosphere would be, at least indirectly, solar-powered.

"The energy released could even be used by organisms to heat their surroundings, helping them to create their own liquid croenvironments," says Grinspoon. "In environments that are energy-rich but liquid-poor, like the near-surface of Titan, natural selection may favor organisms that use their metabolic heat to melt their own watering holes."

The team says these ideas are quite speculative but useful in that they force researchers to question the definition and universal needs of life, and to consider the possibility that life might evolve in very different environments.

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We really need to get back to Titan ASAP, specifically to test for such possibilities of life in a systematic manner.

 

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When they discover some good fishing lakes on Titan, then I'll book a ticket there. Until then, I'll let it warm up a little first. I don't think I'd like fishing much for 'frozen' Titan trout.

May_wentee

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I'm going out on a limb here, but was that a subtle reference to Kurt Vonnegut. In the Sirans of Titan - or was it Slaughterhouse Five, Kurt has the hero, Kilgore Trout, transferred (by chronosynclastic infundibulum) to a dome on Titan. Or am I just having another of my episodes?

 

If methanogens are thriving on Titan, their breathing would deplete hydrogen levels near the surface to one-thousandth that of the rest of the atmosphere. Detecting this difference would be evidence for life, (no known non-biological process on Titan could affect hydrogen concentrations as much).

An easy test for this idea may come from the data from the GCMS instrument on the Huygens Probe , which recorded Titan's chemical make-up as the probe descended.

 

Why would the hydrogen levels be depleted only near the surface if there is methanogen life present? Doesn't diffusion occur on Titan for some reason?
The atmosphere of Titan superrotates, so there is plenty of wind.

 

Life in Titan would be an amazing disovery! Even microscopic life....are they celular beings like in eart? Do they have DNA? How they interact with surroudigs? etc...so many interesting questions. I hope that in the next ten years scientists can find alien life here in solar system (be it in Mars, Titan...whatever) and they can bring it to earth.

 

Indeed, the winds on Titan are found to be flowing in the direction of Titan's rotation (from west to east) at nearly all altitudes. The maximum speed of roughly 120 metres per second (<i>430 km/h</i>) which was measured about ten minutes after the start of the descent of the Huygens probe, at an altitude of about 120 km.

However, the winds are weak near the surface; they increase slowly with altitude up to about 60 km.
Titan's atmosphere, which is about 95% nitrogen and 5% methane, also has a pressure near the surface that is one and a half times the Earth's sea level pressure. atmospheric pressure -- similar to earth.
The reason why hydrogen would be lower near the surface, would be because of the extreme cold.

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If methane-producing microbes exist then they would perhaps find a habitable zone near warm volcanic sources or deep within titan.

The microbes would `consume` the hygrogen.

Incidentally, the ratio of carbon isotopes C¹² and C¹³ in Titan's atmosphere, measured by the Gas Chromatograph and Mass Spectrometer instrument, indicate that methane is being replenished on the freezing world.

It was predicted that lighter isotopes of oxygen and nitrogen would have escaped (<i>fractionation</i>) from the atmosphere into space at a greater rate than the heavier isotopes. This would change the isotopic ratio of the elements.
But the atmospheric carbon isotopes do not show this, implying the gas is being replenished. Continuing geological activity beneath the surface, or life, may be the source.

It might be possible to detect life’s chemical signature by looking at the relationship of two forms (or isotopes) of the element carbon – C¹² and C¹³.
Living cells on Earth preferentially incorporate C¹². So compounds produced by living things could be depleted of "heavier" isotopes such as C¹³, and have a high C¹²/C¹³ ratio.

This ratio would also be present in data sent back by Huygens.

 

Thanks blobrana, nice info! Its amazing that the pressure its similar to earth. Earth its about 70% nitrogen (in the atmosphere) and in Titan its 95...not that much difference. Even so, Titan its extremly cold for life. I wonder which is the tempereture near volcanos.

 

Do you necessarily need carbon for life or that just happens to be all the kind of life that we know of?

Do we even have a definition for life!?!?!?

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Yaba Daba! :m:

 

What is life? good question..life in its most simple form its just a being that makes exchanges (energy and matter) with the surroundings.

 

Stars exchange matter and energy. Are they alive...?

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Yaba Daba

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:m:

 

Thats what i mean: what is the difference between a cell and a star (in a structural point of view)? I am not speaking about Gaia (living planet) stuff and the like, just saying that its hard to define "life" concept.

What about sentient life? A bug its a living bein...why not a robot? There are robots with functions near the ones that a bug make. There are even robots able to self replicate (early stages of course). Why not saying that some robots are alive?

Its hard to say what is and what is not life.

 

Hum,
If it bleeds then it can be killed…


But before the thread goes philosophical; I think the exobiologists are hoping for a carbon based life form on Titan.

 

What about bacteriae?

Fine. But they might find something more interesting if they are more open about what they are willing to search...

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Precisely.


I would define life as "a cohesive system which consciously affect the causes and effects of its environment".

That way we put the focus inward, rather then just analyzing the relationships.

 

Thats a nice definition for life, but you said that the system "consciously (underline that word) affects..."...not every being has a conscience, like bactereas for instance. This is for shure a nice discussion, but its better to not expand it here or will become to much of topic.

Coming back to the topic, yes, i agree that scientists much start to open their eyes to new things. Who know if the life form they are seeking for is very similar to a normal rock in the planet, or even to a liquid...

They must search for "strange" things. Starnge doesnt mean ufos or inteligent life (altought that can happen too...we never now). By strange i mean something diffeent from usual. Imagine that the life in Titan are smal beings that are very similar (externally) to rocks. Such "rocks" would have a strange behaviour: they would move (probably) or have any way to search for "food", etc. Probably we have the picutr of an alien and we dont know it

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Alien rocks!

 

Hum,
Like in that star trek episode where the miners on an alien planet found thousands of `Spherules` that turned out to be studio props?

The one argument I can think against that is the absence of those life forms here.
If they have evolved on Titan, then they would surly have been transported through impacts to the other moons, and eventually here.

I of course assume we haven’t over looked them here.


@TruthSeeker

>>What about bacteriae?

Doh!

 

I define conscious as an active form of relationship with the environment (that is, CHOICE).

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Btw... this IS part of the discussion.

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Yaba Daba! :m:

 

blobrana: i dont see star trek, so i dont know nothing about such "spherules"

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That idea was just a random idea that occured to me, in order to show how the scientists must open their eyes.

truthseeker:how can we say that a bug, a bee, a fly,etc, will indeed "choose" something? They have a kind of "progamming" (DNA) that tells them to do things. The way the choose their options can be very similar to the way that a computer programming, a robot, whatever, will choose options too.

I can create a simple programming where small beings created by me will choose what to do. One say i saw a very simple programme like that (created with blitzbasic) where small green and red dots "walk" in the monitor. They search for food, they create "childs" and so on. Whats the main difference between them and bactereas or bugs? They have their "options" too...i really dont know the answer, but i think that there is no life, just a process. Sometimes, "chunk" of organic (or not) matter will take conscience of their own existence.

I believe that its not too far away the day where we will see a AI emmerging from a computer, a robot, whatever.

Those questions about life and conscience are really very interesting. I read some very nice things about conscience in some Buddhist scripts from great monkeys/sages. I advise some reading on that area, because the way they put the question about life and conscience its great.

Finnaly, Truthseeker, is that avatar the picture of Alf, from the Tv series? I miss that crazy and nice alien!