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TOPIC: Titan Life
Blobrana


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RE: Titan Life
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We may not be alone ...

NASA Brainiac types have found, using the Cassini orbiter, is something rather odd on Titan, the big daddy of moons orbiting Saturn.
Hydrogen and acetylene rain appears to be missing. It's not on the surface where it should be. Now, it's entirely possible a chemical process is getting rid of it. On the other hand, they say, something on the surface could be using it for lunch.
No little grey men, you understand. Something primitive like bacteria. Still, it's enough to make my spine tingle.
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Blobrana


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Have we discovered evidence for life on Titan?

Recent results from the Cassini mission suggest that hydrogen and acetylene are depleted at the surface of Titan. Both results are still preliminary and the hydrogen loss in particular is the result of a computer calculation, and not a direct measurement. However the findings are interesting for astrobiology. Heather Smith and I, in a paper published 5 years ago (McKay and Smith, 2005) suggested that methane-based (rather than water-based) life - ie, organisms called methanogens -- on Titan could consume hydrogen, acetylene, and ethane. The key conclusion of that paper (last line of the abstract) was "The results of the recent Huygens probe could indicate the presence of such life by anomalous depletions of acetylene and ethane as well as hydrogen at the surface."
Now there seems to be evidence for all three of these on Titan. Clark et al. (2010, in press in JGR) are reporting depletions of acetylene at the surface. And it has been long appreciated that there is not as much ethane as expected on the surface of Titan. And now Strobel (2010, in press in Icarus) predicts a strong flux of hydrogen into the surface.

This is a still a long way from "evidence of life". However, it is extremely interesting.

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Blobrana


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Two new papers based on data from NASA's Cassini spacecraft scrutinise the complex chemical activity on the surface of Saturn's moon Titan. While non-biological chemistry offers one possible explanation, some scientists believe these chemical signatures bolster the argument for a primitive, exotic form of life or precursor to life on Titan's surface. According to one theory put forth by astrobiologists, the signatures fulfill two important conditions necessary for a hypothesized "methane-based life."
One key finding comes from a paper online now in the journal Icarus that shows hydrogen molecules flowing down through Titan's atmosphere and disappearing at the surface. Another paper online now in the Journal of Geophysical Research maps hydrocarbons on the Titan surface and finds a lack of acetylene.
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Blobrana


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Hints of life found on Saturn moon

Two potential signatures of life on Saturn's moon Titan have been found by the Cassini spacecraft. But scientists are quick to point out that non-biological chemical reactions could also be behind the observations.
Titan is much too cold to support liquid water on its surface, but some scientists have suggested that exotic life-forms could live in the lakes of liquid methane or ethane that dot the moon's surface.
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Blobrana


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Scientists analysing data gathered by Cassini have confirmed the presence of heavy negative ions in the upper regions of Titans atmosphere. These particles may act as building blocks for more complicated organic molecules.
 The discovery was completely unexpected because of the chemical composition of the atmosphere (which lacks oxygen - responsible for forming negative ions in the lower ionosphere of the Earth - and mainly consists of nitrogen and methane). The observation has now been verified on 16 different encounters.

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Blobrana


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Organic building blocks
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Scientists analysing data gathered by the Cassini spacecraft have confirmed the presence of heavy negative ions in the upper regions of Titans atmosphere. These particles may act as organic building blocks for even more complicated molecules and their discovery was completely unexpected because of the chemical composition of the atmosphere (which lacks oxygen and mainly consists of nitrogen and methane).

atmosphere
Saturns moon Titan is the second largest in the solar system -- and the only one with a dense atmosphere. The atmosphere nitrogen and methane resembles that of the early Earth.
Credit NASA

Cassinis electron spectrometer has enabled us to detect negative ions which have 10,000 times the mass of hydrogen. Additional rings of carbon can build up on these ions, forming molecules called polycyclic aromatic hydrocarbons, which may act as a basis for the earliest forms of life" - Professor Andrew Coates, researcher at UCLs Mullard Space Science Laboratory and lead author of the paper.

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Blobrana


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The Huygens probe
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Almost one year has passed since ESA’s Huygens probe landed on Saturn’s largest moon, Titan. Today, a set of new wide-ranging results from the probe’s two-and-a-half hour descent and landing, part of the extraordinary NASA/ESA/ASI Cassini-Huygens mission to Saturn and its moons, is ready for release.


Huygens probe descending through Titan's atmosphere

At the same time, ESA’s Mars Express mission is continuing its investigations of Mars, painting a new picture of the 'red planet'. This includes the first ever probing below the surface of Mars, new geological clues with implications for the climate, newly-discovered surface and atmospheric features and, above all, traces of the presence of water on this world.

These and other exciting findings from just one year of observations and data analysis - in the context of ESA’s overall scientific achievements - will be the focus of a press conference to be held at ESA Headquarters in Paris at 16:00 on 30 November 2005.

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Blobrana


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Titan Life
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The chemical signature of microbial life could be hidden in readings taken by the European Space Agency's Huygens probe when it landed on Titan in January, 2005.

Chris McKay of NASA's Ames Research Centre in Moffet Field, California, thinks that some of Titan's methane could be coming from methanogens, or methane-producing microbes.
He and Heather Smith of the International Space University in Strasbourg, France, think the microbes would breathe hydrogen, and eat organic molecules drifting down from the upper atmosphere such as acetylene, ethane and more complex organic gunk known as tholins.
Their work is to be published in the journal Icarus.

Ethane and tholins only provide a little more than the minimum energy requirements of methanogenic bacteria on Earth, but acetylene, yielding six times more energy per mole as either ethane or tholins.
McKay and Smith calculate that 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 striking evidence for life, because no known non-biological process on Titan could affect hydrogen concentrations as much.

One test for their 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. It will take time to analyse the raw data, partly because hydrogen's signal will have to be separated from those of other molecules.

"Eventually, I hope, we will have numbers for at least upper limits for hydrogen" - Hasso Niemann of Goddard Space Flight Centre in Maryland, principal investigator of the GCMS.

Acetylene could be easier to analyse, and it too might betray life. "I would guess that there would be a similar fall-off of acetylene if the microbes are eating it" - Chris McKay.

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