Is Curiosity actually equipped to be able to distinguish between these two possibilities, however?
No. As I said, no one expects Curiosity to find life. Instead, it's looking for signs that there was a time when Mars could have supported life. That's as far as it can reach. I mean, if it finds a fossil it can obviously send us pictures of it, but that would be a lot luckier than just winning the lottery.
Even if we were to find fossils on Mars, that wouldn't allow us to take DNA samples, as fossils are not actually the same stuff as the creature that "became" the fossil. (A fossil is basically rock that forms in the shape of the bones that it sort of replaces, so what you see in the museum isn't actual dinosaur bone.)
I have no idea if fossilisation on Mars would work similarly to how it does on Earth. Maybe Mars could sustain the remains of ancient organisms well enough to enable us to take DNA samples, but for some reason I find that unlikely.
If we find extant life, however, there's no question that we can examine its genome. But first we'd have to get the right sort of lab on Mars - or get the samples from there to somewhere where we can study them (so either the Earth or the ISS.)
If its genome is very different from ours, I imagine it'd take a while and a couple of mistakes to find a way to examine and understand it. But if it's the same sort of stuff that we have here, examining the genome is not a huge challenge. (Don't get me wrong - DNA isn't actually one of the easier subjects to experiment on, but it's not among the hardest, either.)
edited 28th Sep '12 3:17:42 AM by BestOf
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