Outer space is not friendly to life. Extreme temperatures, low pressure and radiation can quickly degrade cell membranes, destroy DNA and kill any life-forms that somehow find themselves in the void.

But by banding together, some bacteria can withstand that harsh environment, shielded from the extremes of space by the group’s outer layers. Microbes huddled in the heart of balls of Deinococcus bacteria as thin as five sheets of paper have survived on the exterior of the International Space Station for three years, researchers report August 26 in Frontiers in Microbiology. Such microbial arks might be able to drift among planets, spreading life through the universe, a concept known as panspermia.

Previous research found that microbes can survive in space when embedded within artificial meteorites. But this is the first study to show that microbes can survive this long unprotected, says Margaret Cramm, a microbiologist at the University of Calgary in Canada who wasn’t involved in the study. “It suggests life can survive on its own in space as a group,” she says, providing another possible avenue for panspermia. It also adds weight to the worry that human space travel could unintentionally introduce life to other planets (SN:10/29/19).

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