The Animal That Survived Outer Space
In 2007, scientists strapped a few hundred tiny animals to the outside of a spacecraft, sent them into orbit, and exposed them to the raw vacuum of space. No air, no pressure, brutal cosmic radiation and unfiltered sunlight.
Ten days later, a surprising number of them were still alive.
The animals were tardigrades — moss piglets, water bears — eight-legged micro-animals barely a millimeter long, first described by German zoologist Johann August Goeze in 1773. You have probably never seen one, but they are everywhere: in the moss on your roof, the damp soil of your garden, the sediment at the bottom of the deepest ocean trenches.
Their secret is a trick called cryptobiosis. When water disappears, a tardigrade curls into a dry ball called a tun, sheds nearly all the water in its body, and slows its metabolism to about 0.01% of normal. It is not quite dead, but it is not alive in any way you would recognize. In this glass-like state it has been revived after decades — including one famously revived in 2016 after 30 years frozen in Antarctic moss.
Once it is a tun, the tardigrade barely registers as biology. It can endure temperatures from near absolute zero to around 150 °C, pressures six times greater than the deepest ocean trench, and radiation doses hundreds of times stronger than anything that would kill a human. In 2016, researchers in Japan found part of the answer: a protein called Dsup that wraps around the tardigrade's DNA like bubble wrap, shielding it from radiation damage.
And here is the best part: when water returns, the tardigrade wakes up. It unfurls its legs, ambles off, and eats — as if nothing happened.
They are a reminder that life is tougher and weirder than our everyday experience suggests. We search for hardy life on other planets, yet some of the hardiest life of all has been in the moss under our feet the whole time.
Would you volunteer to be put in a tun state for a century? Tell me in the comments.
Sources: FOTON-M3 mission results (Current Biology, 2008); Japanese Antarctic revival study (Cryobiology, 2016); Dsup protein (Nature Communications, 2016).