In 2007, three microscopic animals survived exposure to unfiltered sunlight in space.

Aboard the FOTON-M3 satellite, tardigrades endured ten days in orbit without air or water. Most survived the vacuum, but intense solar ultraviolet radiation killed nearly all of them. Three came back alive.

Scientists have since discovered extraordinary proteins that protect tardigrade cells and help repair damaged DNA. But the best-known explanation doesn't account for those three survivors.

**We still don't know exactly how they survived.**

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**IN THIS EPISODE**

— The 2007 experiment that exposed living animals to open space

— Why three tardigrades survived deadly ultraviolet radiation

— The extraordinary proteins that protect and repair their DNA

— Why scientists still cannot fully explain their survival

**SOURCES**

Jönsson et al. — Current Biology (2008)

Hashimoto et al. — Nature Communications (2016)

Boothby et al. — Molecular Cell (2017)

eLife — Tardigrade radiation resistance research (2024)

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Narration in this episode is AI-assisted. Research, writing, and editorial decisions are human.

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