Monday, April 18, 2011

An Astrobiology Dichotomy

For today's post I want to compare two places in our solar system. You dear readers will be asked to guess what and where these places are and to surmise if life could be possible in either of these environments.

The first is place found to be nearly devoid of water. Any possible nutrients are relativly far flung. Each daily cycle can see temperature changes of 100 degrees or more. For days on end the sun beats down this environment with its harsh unrelenting rays. Anything that might reside here, when not buried under intense incoming solar radiation is beset with life threatening storms one after another for months on end. There is a relatively thin atmosphere in the locale described but fully 1 out of every five atoms is a toxic gas known to strip electrons from every tissue in your body. Under laboratory conditions this gas has been known to cause profound chronic wasting age accelerating conditions. It gets better because more than three quarters of this locations "atmosphere" contains elements bound together in a stiffleing combination barely able to be metabolized only by the heartiest of organisms.

That was environment number 1. Now let's compare this with environment number 2.

Imagine a place that never changes. Shelter is not needed because as far as is known, there are never any storms. The temperature has the temperature of a cozy heated bath, all day, all year for years on end. Food is piled upon you in heaps 15 stories high! Water is plentiful and readily abundant. In location #2. The equivalent of the entire volume of the world's ocean flows every few million years. In short it seems like a biotic paradise.

So what and where were these two locations I described? Surprisingly, they were both here on Earth. Location number 1 was the Tiaga of Northern Russia, one of the largest land ecosystems on Earth! But what about all of that horrible stuff you mentioned? Its all true. Russia holds the record for greatest temperature change in one day. -20 F just before dawn +80 F around noon. The Russian winter is famous for wiping out intrepid life forms brave enough to attempt conquering it. Two known species were nearly driven extinct because of it e.g. Napoleon Bonaparte and Adolf Hitler. But what about that toxic gas you mentioned? Is there really a toxic gas leak in Russia? No. The toxic gas I mentioned is Oxygen. We take it for granted that we can breathe it, but one only needs look at what it does to a banana or an apple to realize its toxic effects. Does it really strip electrons from every tissue in your body? Yup. That's how we are able to get energy from food. Oxygen is the final electron acceptor in our electron transport chains. Because of oxygen's greed for electrons we are able to make 18 times more ATP than organisms that don't utilize this toxic substance. And the 78% of the atmosphere we can't guessed it--Nitrogen. N triple bonded to N is ridiculously hard to break apart, only a select few bacteria found in peas and other legumes can even tackle the immense task of splitting this titanic bond.

Environment number 2, also here on Earth, is a deep sea vent less than an hours walk from the surface--assuming you could walk a matter of miles straight downward AND resist the 100 atmospheres of pressure crushing you into oblivion. Though we are not able to metabolize the hydrogen sulfide running rampant in these deep sea oases to chemiosynthetic bacteria this IS their food source.

In light of the present argument I am inclined to believe the John Corliss argument. I think if life had to originate in one location it was probably a deep sea vent. It seems a lot more difficult for life to start in a shallow sea with dilute nutrient concentrations than in a place with a 150 foot pile of food replaced continuously. Ladies and gentlemen Beware your land based mammal biases on the world. Did I mention the deep sea vent is home to approximately 1,000 different species-- roughly 120 times that of a rainforest if is correct in its analysis!

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