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Hi Craig. Interesting thread
I guess no-one will know what forms of life can exist elsewhere till someone finds some. In the meantime, it probably makes sense to assume that they will be based on carbon, due simply to the unique chemical properties of that material. Apart from that, life-forms could have any structure, since, on Mars they could have had maybe 3 billion years to evolve in that totally different environment.
I doubt that minor issues like an increasingly toxic environment would make much difference to continuance of life once it got started - crikey there are bacteria in our hospitals that happily live in antibiotic environments that would have completely written them off only 50 years ago. Once life gets going it seems that you can't kill it with a stick - providing the environment changes slowly enough, it will adapt without even being aware of change. Our bugs might die on Mars, but the locals should be quite at home - if they exist.
Thus, since it is not likely that we can guess what forms life would take on Mars, the best starting point is to assume only that they will be carbon based and will require some form of water and energy. They will also produce waste and that is what I assume NASA is looking for - gas from decaying remains or alien crap. There may not be life in any form that we know, but any carbon life-form will produce recognisable waste.
Regards Ray
Last edited by Shiraz; 09-09-2011 at 10:21 PM.
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