The Search for Extra-Terrestrial Life
Wednesday, January 19, 2005
The search for extra-terrestrial life is one of the most exciting areas of long-term space exploration. By that, I am not refering to the silly 'UFO' type of search; I'm talking the search for those planets capable of sustaining life and the exploration of such planets.
However, I think that search is overly biased in terms of our own 'traditional'
form of life. I remember a presentation on the exciting finds on Jupiter's moon Europa, that seems to indicate the presence of a salty ocean underneath a layer of ice, possibly as thin as one mile thick. One scientist, obviously quite nervous about going out so far on a limb as to suggest the slight possibility of life uderneath that ice. But, he was quick to point out, it would be simple microbial forms at best.
That statement convinces me that they are thinking with Earth-based blinders on. Just because life here that exists without oxygen and dependent on chemical processes without light (anaerobic lithotropes) is only microbial, doesn't mean that's all they'd be there. They wouldn't face competition from the more energy efficient processes involving light and oxygen, so who knows.
For those interested in the type of biochemistry involved, here are a few links (stuff I had to memorize a couple decades ago :):
Sulfur Cycle - Nitrification Cycle - Non-traditional Biochemical Cycles
And all of this assumes water as the solvent of life, which is the only form we know. Does that preculde the possibility of another solvent of life, such as liquid mehane? And, if such life could exist, would we even be able to recognize it as life? It seems highly unlikely, but there has been very little research on complex molecular structures at temperatures that far below our ambient temperature. We simply don't know.
Think the above sounds far-fetched? How about life thriving around underwater volcanic vents at boiling temperatures? Or living organisms in burning coal refuse piles at ph 0 and sixty degrees Centigrade? Both exist right here on Earth; living proof that life is really stubborn.
