Gallery: Martians Might Be Real. That Makes Mars Exploration Way More Complicated
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Tardigrades These [rotund little animals](https://www.wired.com/2014/03/absurd-creature-week-water-bear/) can withstand extreme heat, cold, pressure, and radiation. In 2007, the European Space Agency sent more than 3,000 tardigrades into space for 12 days. Two thirds of them came back unscathed.
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Nematodes Also known as roundworms, some of these critters can freeze their metabolism when there’s no food or oxygen and enter a state called cryptobiosis. Nematodes were the only known survivors of the space shuttle *Columbia* disaster.
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Cave Bacteria In 2006, a group of microbiologists discovered a colony of bacteria in a deep fracture of a South African gold mine, more than a mile down. The colony had survived for millions of years without ever being exposed to the sun.
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*Bacillus pumilus* The spores of this bacterium display unusually high resistance to the treatment that NASA uses to sterilize rovers before they’re sent off to space. So it’s a decent bet that some of these are still stuck to the Curiosity rover, now on Mars.
