ESA exposed 3,000 tardigrades to space in 2007; 68% revived after rehydration.

Microscopic tardigrades endured open space conditions during a 2007 European Space Agency mission. These water bears survived vacuum exposure and significant radiation doses in low Earth orbit. Most specimens revived after rehydration, though some later died from radiation effects. This experiment marked the first time an animal endured fully open space without any shielding. The findings demonstrated tardigrades’ remarkable resilience to extreme extraterrestrial environments.