Humans can survive unprotected in space for a few minutes before the air in their lungs expands, gas bubbles out of their blood and the saliva in their mouths begins to boil. In contrast, a tiny animal, reaching 1.5 millimeters in length, can survive for days in the harsh environment. Known as tardigrades, or water bears, they are found all over the world, from the sediments on the ocean floor to the lichens on mountaintops. In an adaptation to desiccation, some tardigrades can persist for a decade without moisture. Tardigrades that went into orbit last year faced the vacuum of space for 10 days and survived. Only when they also encountered radiation did the water bears capitulate—just 10 percent made it. Much like the bacterium Deinococcus radiodurans, the tardigrades that survived must have some mechanism that repairs cellular damage. The researchers who describe the space-faring tardigrades in the September 9 Current Biology speculate that other creatures adapted to survive extreme dryness—such as rotifers, nematodes and brine shrimp—might share the tardigrades' ability to endure space.
This article was originally published with the title "Space Suits Them" in Scientific American 299, 5, 34 (November 2008)