Another question : which of the Planetary Society's Huygens landing on Titan art contest entries do you think came closest to representing the actual scene ? ....see http://planetary.org/saturn/artcontest.html

I think this one came pretty damned close : http://planetary.org/saturn/contest/artur_rataj.html

.....although this one looks pretty good too : http://planetary.org/saturn/contest/emile-raphael_franco.html

as does this one : http://planetary.org/saturn/contest/steven_hobbs.html

But personally, I was hoping for something like this : http://planetary.org/saturn/contest/bryce_jacobs.html

I loved the art too. Especially the last one, Jaro. Talk about getting 'carried away!'

All other things being equal--I believe that is essentially correct. I don't think life could exist on Titan--certainly not life as we understand it. Although the temperature is just about right for high-temperature superconductors--perhaps some form of superconducting crystaline life--pretty exotic and not very likely.

My guess is that life--if and when it is found--will probably resemble primitive Earth forms. Now this isn't just a lack of imagination on my part--it's because the really primitive forms from Earth's past represent some of the sparcest minimums needed to sustain life at all. The simplest life forms will probably be the most numerous from a purely statistical point of view, and are farely easy to detect. Also, because of this, detecting evidence of past life forms can be as simple as searching for micro-fossils with a microspcope. This is one reason why I would like to see a mini-electron microscope or miniature optical microscope packed into the scientific package for the MSL (Mars Science Laboratory) Rover mission for 2008..

Without getting into detailed discussions about DNA and the basis of life--I believe that with only one data point (our Earth Life Form point of view) that we still can make some educated guesses as to what we may find based on some straightforward assumptions.

As you say, life needs an energy source. An obvious energy source is photon energy (light.) Life on Earth developed photosynthesis billions of years ago. Photosynthesis was (is thought to have been) responsible for transforming Earth's early reducing atmosphere (similar to Titan's possibly) into the oxidizing atmosphere we have today.
Sunlight powers this active process. And photosynthesis is so prevalent on Earth that the spectral signature for chlorophyl is detectible from space. Given a sufficiently large network of optical telescopes at interstellar distances, the characteristic absorption spectra of chlorophyl, oxygen and methane are all detectible--giving an almost unmistakable signature for life. Similar processes are likely to work elsewhere, so if we look for similar signatures then we may just find evidence for life on other terrestrial worlds.

Suitable chemistry: the organic complexities of carbon are universal and unrivalled by any other element. Silicon chemistry is possible, but since carbon is lighter it is likely that compact, energetic chemsitry involving carbon will be statistically preferred--Darwinian selection will probably ensure that. And so we may hypothesize that it is almost certain that any life we find elsewhere in the universe will also be carbon based.

Suitable solvent: water is one of the simplest molecules in the universe, and the components to make water are also abundant. It seems likely that wherever terrestrial worlds have formed that also have abundant carbonaceous material will also likely have abundant water. Ammonia based chemistry is also possible, but the chemical reactions involving carbon are very slow at the conditions at which ammonia is likely to be a liquid. Ammonia silicon chemistry doesn't seem even remotely likely. Carbon/water chemistry seems like a good choice--and it certainly works for us.

It is all a series of guesses, of course, but they're pretty good guesses. This makes me think that the most likely place to find life in our solar system beyond Earth is probably Europa. Europa is likely to have all of the essential ingredients, including energy (in the form of chemical seeps at the bottom of its ocean.) The most likely place we will find evidence for past life is probably Mars. If we find life on Mars, I would hypothesize that it stands a very good chance of being closely related to primitive Earth forms. Why? Because past meteorite impacts will have likely blasted chunks of rock from one body to the other. Chances are pretty good that aleast in some of those rocks, microbes survived the violent ejection process and the long cruise through space. Thus I conclude that cross 'fertilization' may have been likely between Earth and Mars in the past. Moreover, since Earth is heftier than Mars, I would add that the probability vector for transport of life points from Mars to the Earth! (Now hows that for a startling idea?)

Cryovolcanism is almost probable on Titan given the apparent weather activity and presence of landforms there. Certainly hotspots are favorable for pockets of life. Wouldn't it be fantastic if we ended up finding life EVERYWHERE we looked where conditions were favorable for it to be? Such a finding would be astounding and would imply a Universe filled to the brim with life. Surely in such a universe intelligence would have arisen many times, and we would thus be one of many millions of species contemplating the cosmos...

But Chemisty is governed by statistics--and that doesn't change no matter where you are in the observable universe. The basic processes which apparently created life here on Earh, operate everywhere--so the basic chemistry ought to be pretty much the same. That isn't to say that different conditions may not achieve different results--only that the robustness and variety of carbon-based life seems favourable for the formation of such carbon-based life elsewhere...

How about this :

http://www.space.com/scienceastronomy/ap_huygens_update_050127.html

Titan's Methane Not Produced by Life, Scientists Say

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Based on data collected by Huygens' instruments, Sushil Atreya, a professor of planetary science at the University of Michigan in the United States, believes a hydro-geological process between water and rocks deep inside the moon could be producing the methane.

"I think the process is quite likely in the interior of Titan," Atreya said in a telephone interview.

The process is called serpentinisation and is basically the reaction between water and rocks at 100 to 400 degrees Celsius (212 to 752 degrees Fahrenheit), he said.

<SNIP>

Indeed,

Could be life in Titan's interior. A deep drilling rig on Titan may bring up microbes from several tens of kilometers down...who knows?

I suspect that a first attempt at detection of life beyond Earth may be made on Mars, in the deep saline aquifers that are thought to be there; then Europa with an ice penetrating probe; and then Titan.

I'm sure humanity will learn a lot in the attempts--which makes the whole thing worth it.

Looking at the very sparse radar imaging coverage of Titan by Cassini, it seems to me that NASA/ESA should put Cassini into orbit around Titan, to get a complete, detailed global coverage.

The question then arises whether this can be done.

Looking at the planned Cassini orbital tour, at http://www.esa.int/SPECIALS/Cassini-Huygens/SEMD6E2VQUD_0.html (click on "fast animation" above the window) ....I see that in early 2007 that Cassini orbits get quite circularised, approaching the orbit of Titan --- it should not require huge propellant expenditures from there, it seems, to slip into Titan orbit.

Any thoughts ?