Life on Saturn's Moon Titan.

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I find this fascinating. Scientists have delved into what methane-based life forms may look like. This is so interesting because such organisms would have a tremendous time existing anywhere but on Titan. It's neat to think of how other organisms would be challenged outside of their own environment instead of just how we would be.

http://phys.org/news/2015-02-life-satur ... titan.html

I think that it's highly unlikely that there's life on Titan. Hypotheses about non-carbon based life are interesting nonetheless though.

It opens up the world of the imagination thinking about them and how they might exist.

Carbon based life could exist under the ice surface of Titan given a number of factors:
1) Liquid ocean under the ice is low enough in salt content to support Earth like sea creatures
2) Volcanic activity from Titan's rocky core would provide a useful heat source to encourage life forms to exist
3) Dense nitrogen atmosphere around the surface of the moon would provide benign conditions for life to form

More likely than not there are no life forms on Titan, but in the distant future Titan could be a natural incubator for life to form.

The temperature on Titan is minus 170 degrees. Any life there would have to be resilient to cold as life resilient to heat on somewhere like Venus. It is so cold that liquid methane trickles on the surface.

Europa is the best chance for life beyond Mars. There is supposed to be thick oceans under the icy crust with volcanic vents to heat up the water.

But there is liquid water underneath the ice on Titan meaning the temperature is above zero degrees centigrade. If there are volcanic vents coming from underneath the ocean, then the temperature could be well above zero.

The problem concerning life forms developing on Europa is contending with the gigantic magnetic fields generated on Jupiter.

Also, don't forget that the conditions for life that Thomas is thinking about are for carbon based life while the article was talking about methane based life. Theoretically, life that is not carbon-based like the life on Earth might be able to exist in environments that are extreme to life as we know it from earth but might not be able to exist in an earth like environment.

The running debate about an alternative to "carbon based life" in outer space centers on the possibility of "silicon based life" because like carbon silicon is an element that has the capability of forming complex molecules (which might, or might not, be able to do the equivalent of what carbon does on earth in some kind of weird non earth environment).

I'm no biochemist, but I know that methane is not an element (like either carbon, or silicon), but a complex molecule. And its a molecule based on carbon. So "methane based life" IS carbon-based life. In fact methane is made by living things on earth, and its also generated in coal mines (coal is fossilized carbon based life).

Well there is an abundance of methane on the moon of Titan, so isn't it logical that if life forms develop on Titan they will be carbon based.
Also, there is an abundance of Silicon on the planet Earth, so why haven't Silicon based life forms co-evolved with the carbon based life forms on Earth?

None of that has anything to do with my point. And I dont see what your point is.

Constrasting "carbon based life" with "methane based life" sounds dumb because (a) methane itself is "carbon based", and (b) its peaches and pears (carbon is an element, and methane is a compound so theyre and not comparable things anyway).

My point was that saying "methane based life and not carbon based life" is like saying "Nebraskan and not American". Methane based life would be a subset of carbon based life (like Nebraska is a subdivision of the USA). So its a self contradictory statement.

So if Titan had "methane based life" then it would BE "carbon based life" (like we are). In fact it would be very similiar carbon based life to us.

In contrast silicon IS an element, and thus IS comparable to carbon.

And it just so happens that (as any sci fi buff knows) there is a notion that "out there" there could be planets with life based on silicon rather than on carbon (like we are).

The fact is that we dont have silicon based life on earth for whatever reason. But on some other planet with a different atmosphere, and a different temperature regimes. or different gravity, carbon molecules might fall apart, but silicon based molecules might thrive and complexify. Am not up on the latest thinking on it, but decades ago the consensus was that "living quartz rocks" were unlikely to evolve even on other planets for some reason. But its a running debate in exobiology.

What about lifeforms like waterbears http://en.wikipedia.org/wiki/Tardigrade?

Similar creatures can live in absolute zero (−273.15° C) and 100 C

Yes, I'm aware that methane is an organic molecule but if you read the article linked to in the OP, the molecular structure that they're talking about is totally different from the kind of carbon based life on Earth. It's a kind of life that replaces water with liquid hydrocarbons, like what you find in the lakes and rivers on Titan, as the medium for chemical and metabolic processes inside cells. At least that's how I understood it.

The same elements and compounds are present on Titan that are present on Earth. This is because the solar system formed at the same time from nuclear reactions within Suns. The ratio of the some of the rare earth elements are different on some of the planets. Hence a meteorite from Mars can be clearly identified. Evolution takes the elements and compounds that are abundantly available to construct life forms. Those life forms will develop in accord with the environment that increase the chances of survival of the species. Hence if there are life forms on Titan they will look and behave differently to life forms on Earth because they have adapted to different environment in order to survive. The molecular structures of those life forms on Titan WILL IN ALL PROBABILITY be similar to those molecular structures of life forms on the Earth. That is they will be DNA molecules with long spiral chains of methane linkages. They won't be a different type of carbon as postulated by OP because organic chemistry is same on every planetary system in the universe. Almost certainly there won't be any Silicon based life forms either where there is a higher availability of carbon, because carbon is the more versatile element being able to form an infinite combination of different carbon chain. In one of the original episodes of Star Trek, a Silicon based life form was discovered on a mining colony deep underground. This was a clever scientific postulation on where a Silicon life form might exist, because deep underground there is much more Silicon for creation to play around with than Carbon.

No, you misunderstand. Organic chemistry will be the same, I never said otherwise. However, in life on Earth, water is considered the "universal medium" in the sense that metabolic processes and chemical reactions inside cells take place in water as a medium, which is why most astronomers look for regions around a star where liquid water can exist on the surface of the planet, called the habitable zone, as places where the probability of life is more likely. The kind of life that they're hypothesising utilises liquid methane as replacement for water, since all the water on the surface is frozen and this would require that the organic compounds used to form the lipids of cellular membranes would have to be different. It's not a "different kind of carbon" as you say and has nothing to do with DNA structure in this case. In fact, I was wrong in saying that it's non-carbon based before but rather it's more accurate to say that they're talking about "methane-based cells" rather than "water-based cells".



That's a quote from the article. I do think it's highly unlikely that there's any kind of life on Titan but I'm just trying to clarify what they are actually trying to say. The article says "methane-based life" but that's not really an accurate term to describe what they're talking about.

I think you are spot on. There are pools of liquid methane on the surface of the moon of Titan and chemical reactions are going on, converting methane to ethane and generating hydrogen. The article is inferring that those methane reactions could be generating a DNA type life form based on liquid methane linkages. I think the notion is ridiculous but any scientific theory however fanciful, is worth postulating because it may lead to alternative theories and discoveries down the track.

This recent SETI talk by Dr. Jason Barnes from the University of Idaho sheds some light on the subject: