Comment by FlyingSideKick | Hacker News Reader

Comment by FlyingSideKick | Hacker News Reader

The discovery of microbial life on another world would be as significant as the Copernican revolution.

If indeed the methane signatures are not from serpentinization and we can somehow figure out how in situ to determine if the methane is indeed organically produced then the next question would be "Are these lifeforms the result of Panspermia"? We will then need to figure out how to sequence the chemistry of of these lifeforms which may require us to redefine the definition of "life" altogether. Regardless of the answer as to life independently forming given a certain set of criteria or if carried by meteorites from world to world such would provide good evidence that the universe is at probably teeming with microbial life will shifting eradicate our geocentric views even further.

Note: I have undergraduate degrees in both Geology and Astronomy. IMO Mars is likely a dead world and these methane signatures are from serpentinization as this is the most plausible scenario.

> We will then need to figure out how to sequence the chemistry of of these lifeforms which may require us to redefine the definition of "life" altogether.

I don't see how; we don't have a definition of "life" to redefine. We basically operate on the simpler system of having a big list of things that are life -- everything is categorized as "alive" or "not alive" without reference to a general definition of the category.

Well, we typically operate from general principles[1] which don't require any particular biology. But of course it could turn out that the biology was similar (if panspermia-style theories are correct, or even just convergent evolution).

1: https://en.wikipedia.org/wiki/Life#Biology

Currently the broadest definition of life would be something like: A self-replicating cellular structure having a metabolism to organize resource input and waste. "Cellular" lets us rule out things like fire and crystals, but viruses and RNA soup are also swept away.

I think if we found a population of some kind of self-replicating RNA analogues on another planet, it would be significant enough to revisit that "cellular" constraint. On the other hand, that definition is already so broad that we could conceivably build self-replicating 3D printers that would qualify as life.

We might also take a top-down approach and come up with a good definition of "ecosystem", and then define living things in terms of their role in an ecosystem.

Everything we consider life now had a common ancestor, and this is de facto definition.

> The discovery of microbial life on another world would be as significant as the Copernican revolution.

The discovery of such remains on Mars would be the saddest thing ever. Like walking along a deserted island and finding a bony corpse's remains-and dealing with the full weight of what once was.

But simultaneously, like discovering the ancient gravesite of what could be your ancestors.

Yeah, and discovering that your ancestors escaped from that planet and came to earth after meeting up Mars. That would be the cheeriest of all discoveries.

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