|MadSci Network: Microbiology|
You have asked an interesting question into what has become a realtively hot field of late, exo-, or xenobiology. Certainly, our knowledge of the tolerances of bacteria and other organisms on Earth enhances our appreciation of the variety of conditions in which that could thrive, but does not necesarily make any direct statement towards life on Io, a Jovian moon.
There are a multitude of strange places where we are discovering life, in hot springs, at the bottom of oceans near volcanic vents, and very recently, bacteria were brought to the surface from a drilling, nearly a mile below the surface. What this information tells us, is that on Earth, the conditions for life need not be 'perfect' and what organisms require, at the minimum for life, is far less than we had appreciated.
As for Archeal life on Io, I am not certain that can be said, but the broader question it raises, is the possibility of life elsewhere in the Solar system, not necessarily Io. Certainly, we understand that the basic necessities for life are simply water, and a source of energy and nitrogen. Some of the more unique organisms get their carbon and nitrogen from rocks, or use sulphur from oceanic vents as their energy source, much as we use oxygen.
People who study these sorts of things, biologists, astronomers and the like have taken a keen interest in the possibility of life in the solar system. Several bodies are of interest, bacause of our understanding of the tolerances of life. Mars is one, primarily because it seemed to have held life once, and there is the possibility of buried Martian water, or microorganisms living beneath the surface. The other two bodies of interest are Io, as you mentioned, and Europa. Europa is of significant interest, because geologic evidence supports that the ocean of Europa may be molten beneath the surface, and if temperatures and conditions are suitable, like may exist. Io, is another target, not because there may be an abundance of water, but due to its heave volcanic activity. Volcanoes are a source of significant chemical energy, both as heat, and elements. They provide a rich environment for complicated chemistries to occur, which may include those associated with life. Certainly in the history of the Earth, volcanoes have had a significant contribution to the development and distribution of life on the planet.
A great question, if you are interested further, you can check out NASA's web site, or more broadly, look at or download the SETI@Home screen saver, so your computer can help analyze radio telescope data for "Signs of Intellignet Life" Thanks.
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