K. Ingemar Jonsson of Kristianstad University in Sweden and colleagues shipped two species of tardigrades aboard a 2007 European Space Agency mission that reached low-Earth orbit, about 160 miles up. Some of the water bears were exposed to the vacuum of space only, while others were exposed to vacuum and ultraviolet radiation.
As the researchers describe in Current Biology, the tardigrades survived vacuum-only conditions quite well. This is perhaps not surprising, since water bears are able to deal with extreme dehydration. In fact, the specimens used in the experiment were already thoroughly desiccated, and upon re-entry they were rehydrated and revived.
But even a few of the specimens exposed to the full spectrum and intensity of ultraviolet radiation — about 1,000 times as intense as that on Earth — survived. Thus the water bears join some lichens and bacteria as the only species known to be able to cope, unprotected, with both vacuum and solar radiation in space. – nyt