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It's in the news that some experiment was able to capture some alien specimens during a meteor shower:

Despite all the skepticism that has already been said about this finding, what would be a proof that such specimem came from outer space? Is there any established protocol to assure that some form of life didn't come from Earth?

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migrated from Sep 21 '13 at 22:34

This question came from our site for scientific skepticism.

Despite me having answered, I think this is off-topic for skeptics, because you're not asking us to verify/falsify a particular claim. Instead, you're asking us for "what would prove something came from outer space?", which I think people over at physics, biology, or space stackexchanges would be much better suited for. Would you mind having this migrated? – Sancho Sep 20 '13 at 17:54
No, please, migrate it to any other stackexchange that suits it better – woliveirajr Sep 20 '13 at 17:56
This question appears to be off-topic because it is a general scientific question. – Suma Sep 20 '13 at 18:55
@woliveirajr I've flagged it for mod attention... expect a migration at some point. – Sancho Sep 20 '13 at 19:17
@LarianLeQuella As I understand it, woliveirajr is interested in the basic science question of "what would prove that something came from outer space?", rather than having the claims of these scientists examined. If he/she is also interested in having the claims examined, that question could be asked here separately, while this one is migrated elsewhere. – Sancho Sep 21 '13 at 22:33
up vote 3 down vote accepted

I wouldn't say that there is an established protocol - claims of alien life are not commonly testable or even legitimate - but if something were discovered and deemed "alive," a fairly good sign it was alien would be if its genetic makeup were based on something other than DNA or RNA. That would be a dead giveaway the organism had side-stepped every known organism on Earth and while that doesn't prove alien-ness, it would certainly hint strongly of a non-Terran genesis. There are arguments for and against carbon/CHNOPS-based life but that is nowhere near as definitive.

Also, there's another really good technique. I don't like to resort to ad hominem attacks, but ideally the discovery should be by someone who has not already made verifiable false claims on the same topic.

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Isotopic ratios could theoretically be useful, in particular carbon or oxygen (a la the Allende meteorite), but there are so many ways to get different numbers that an alien origin hypothesis would rank pretty low. It could be informative but it certainly isn't a magical "push button, get number" scenario. Wonky ratios have already been observed many times for definitely Earth-bound life. – Amory Sep 23 '13 at 2:00

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