Nature
Tardigrades survived days of direct exposure to the vacuum of space
In 2007, dehydrated tardigrades flew aboard the European Space Agency's FOTON-M3 mission and were exposed directly to the vacuum, cosmic radiation, and deep cold of low Earth orbit for over a week with no protection. Most revived within half an hour of rehydration back on Earth, and some went on to lay viable eggs. They survive by entering a cryptobiotic state, replacing nearly all cellular water with a protective glass-like substance.