|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.
|Question Date: 2005-01-19|
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 auto-catalysis 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. 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.
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.
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
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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