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Hi, following recent publicity of the Huygens Titan probe success, I have read reports of large deposits of organic (carbon-containing) compounds such as methane, ethane and acetylene. Surely these compounds are present only if life is abundant? I was under the impression that hydro-carbons were a direct result of organic life, i.e. Oil and Coal etc: My Question is how are these compounds formed if life is not present.
Answer 1:

That's a good question. It turns out organic compounds do not require the presence of life in order to form, even though they make up all living matter on earth. That means that organic compounds must exist for life to exist, but life is not necessary for these compounds to exist. However, there is other evidence that there may indeed have been some form of life on mars in the past. The three materials scientists believe are essential for life are an energy source, liquid water, and organic molecules. Mars is dry now, meaning life cannot exist there,but there is evidence that large amounts of water existed there many,many years ago, meaning Mars once had all of the necessary building blocks for life. There is certainly a possibility that life may have existed long ago on Mars and died off as the conditions on the planet worsened over the years. There is also a strong possibility that life never existed on Mars at all. Titan and Europa (moons of Jupiter) also possess the necessary components for life, but no life has become apparent there either. The big question of whether the continued search for life outside of this planet is a tremendously important scientific endeavor or a complete waste of tax-payer dollars (or something in between) is something that depends entirely on who you ask... If enough people decide it's a complete or even moderate waste of time, the government will stop funding exploration programs and we may never know the answer.

Answer 2:

Organic compounds are NECESSARY BUT NOT SUFFICIENT for LIFE.There are many "organic" compounds that can be made wholly through inorganic reactions!

So the hydrocarbons on titan are of interest because they may represent what we astrobiologists call PREBIOTIC chemistry. That is, on Earth before life arose there undoubtedly were organic materials (by not having come from life per se) that got cooked up and SOMEHOW started an autocatalytic reaction within a drop of oil. These reactions because of autocatlysis can be considered "alive". At any rate, the origin of life remains a mystery. But titan is of interest because it has a wealth of hydrocarbon compounds on the surface and lacks free oxygen in the atmosphere. That is important because free oxygen will rapidly breakdown organic compounds so necessary for life. So Titan MAY be an analogy for the early Earth BEFORE we had free oxygen in the atmosphere. Today we have 78% N2 and 21% O2 in our air. Today titan has N2 and a little bit of CH4, methane. Some geochemists think that the atmosphere of early Earth was similar.
I hope this answers your question.

Answer 3:

Nope -- while it is true that hydrocarbons are the building blocks of life, you don't need living organisms to make hydrocarbons. On Earth,without life, various oxidation reactions would make water, carbon dioxide, sulfuric acids etc, as well as hydrocarbons. Over the last billion years, earth has had a strongly oxidizing atmosphere (due to living organisms) which would rapidly oxidize most free hydrocarbons--
so the hydrocarbons you see here are mostly products of living organisms on the route to decomposition.

On a moon where carbon based life does not exist, methane, and more complex hydrocarbons can be created by UV light, lightening and pressure on carbon, water, methane and other simple compounds.
Even amino acids can form this way --

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