If Mars Once Hosted Life, How Would We Know?

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Despite a few press-stopping false alarms and a long-standing sci-fi fascination, there’s no evidence of biology — microscopic, trilobitish, or creepily humanoid — on Mars. But that hasn’t stopped the Curiosity rover from running around saying “This spot would have been habitable” and “That spot definitely has water.” And it hasn’t stopped astronomer Nathalie Cabrol from searching for the ever-elusive “biosignatures”: evidence, like geological graffiti, that proclaims “LIFE WUZ HERE.” But it isn’t as easy as finding a spray-painted tag. First of all, the life almost certainly isn’t alive anymore. And second of all, it probably hasn’t been alive for a long time. Around 3.5 billion years ago, Mars changed from being a relatively nice place into the frozen radiation-zapped desert it is today. It was never San Juan, but it does seem to have had a milder climate, water oceans, and a thick, protective atmosphere. If this young sub-Caribbean Mars was home to life, that life may have left its mark. The problem is that we aren’t totally sure what that mark might look like. Fossils on Mars To assess the possibilities, Cabrol, who works at the SETI Institute in Mountain View, California, leads a team of earthly explorers who research evidence of ancient life on Earth to learn more about potential ancient life on the Red Planet. The team was recently inducted into NASA’s Astrobiology Institute, which gave them five years of funding to support their work. Cabrol’s team will travel to remote outposts across the world, each of which is similar to the way Mars was at some period of the planet’s 4.5-billion-year history. “Trying to identify the fingerprints of life on Mars begins with better understanding our own biological record and how it is preserved here on Earth in Mars analog conditions,” says Cabrol. By looking for the “LIFE WUZ HERE” tags in our own old sediments, we can learn how to recognize “LIFE WUZ HERE” tags in Martian rocks. And there are three ways that hunt could turn out, says Cabrol. One, maybe life never took hold on Mars. Bummer. See more via DiscoverMagazine.com.

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