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Might Mars Contain Life?
stagmeister writes "According to the BBC, the Viking probes to Mars in the 1970s "detected strange signs of activity in the Martian soil - akin to microbes giving off gas," and that while those findings were not acknowledged as proof of life then, "in 1997, reached the conclusion ... that the so-called LR (labelled release) work had detected life." At the same time, the British are launching a probe to try to find life on Mars."
I would have to agree, this is the tough part. The evidence is 20 years old from Viking, and its still being debated. Remember the martian rocks that "contained signs of life"? Me either.
. We're not even sure what to look for ... at least we're pretty damn sure what water looks like at this point ... these missions are expensive, I wouldn't waste a mission on something unlikely to succeed anyway.
Only three have succeeded so far: the two Viking probes in the 1970s and Mars Pathfinder in 1997.
What are the chances those probes contaminated Mars with terrestrian microorganisms? Since the 1970's it was discovered life is more resilient than it was thought, with bacteria not only surviving, but thiriving, in mediums considered to be sterile - like in thermal water springs or nuclear reactor cores.
The meaning of "sterile" has changed a lot - see what measures NASA is preparing to take now for a (still theoretical) mission to Europa (Jupiter's satellite, for the challenged).
if you use a good enough junk-filter, slashdot.org will display a single, *blank*, page
If we can find life somewhere else out there it's going to be fascinating.
For example, is the life DNA based? All life on earth is DNA based, and if the life elsewhere isn't then we are going to learn a lot by studying it - it will be an using an entirely different mechanism to do essentially the same thing as DNA. How does it work? How did it evolve?
There is evidence for at least _some_ cross-contamination between Earth and Mars occurring. If we find DNA or RNA based organisms there it may just be that they were seeded from here (or vice versa, back when Mars had water and a thicker atmosphere).
The place to look for *really* interesting things is environments that are isolated from ours, or that have conditions different enough that a different basic chemistry would be required.
Thermal vents on Io would be one option - there's lots of interesting sulphur-based chemistry upon which complex organisms could be based.
The oceans of Europa would also be an interesting spot - it's far from earth, and the potentially (earth-like-) life-bearing areas are beneath a thick crust of ice, so cross-contamination is less likely.
Cold worlds like tidally-heated moons of the outer gas giants would also be an interesting place to look. At those temperatures, life would a) run much more slowly and b) have to be based on lower-energy processes and substances with weaker binding forces for the available energy to be used to break down and rebuild biochemicals.
When we finally have probes capable of doing really detailed chemical and biological surveys of the outer solar system, we're going to find some very interesting things. Our own world shows us that microbes, at least, will show up wherever there's the energy and chemistry to support them.