How tiny tardigrades survive the vacuum of space

HostI was looking at some dry moss on an old brick wall today and thinking about how anything can live in a spot that harsh. It turns out there's a tiny creature that makes a hot brick look like a spa. How do these little water bears actually survive in places as empty and cold as outer space?

GuestThey're truly the toughest things we have ever found. Most people call them tardigrades, and they look like little eight-legged gummy bears under a lens. Their real trick is what they do when the water goes away. They don't just die; they turn into a tiny ball called a tun. They pull in their legs, tuck their head in, and dry out until they're almost like a grain of sand. Normally, if a living thing loses that much water, its insides just break down and fall apart. But these guys make a special kind of sugar and special building blocks called proteins that fill up the space where the water used to be. It turns their insides into a solid, glassy shield that holds everything in place so nothing snaps or tangles. It's like filling a house with foam before a storm so the walls can't cave in.

HostBut if they're dry and solid like a grain of sand, they're not really breathing or moving. It feels like they're just dead. How can you call that surviving if the way their body runs has completely stopped?

GuestIt's more like they have hit a pause button on life itself. The way their body runs slows down to almost nothing. This is what lets them handle space. In two thousand seven, scientists put these dried-up tuns on the outside of a rocket for ten days. In the vacuum of space, any water left in a body would boil and then freeze instantly. Since these bears were already dry and glassy, they avoided that whole mess. They just sat there in the raw cold and the blinding light of the sun. When they brought them back to Earth and gave them a drop of water, they woke up in about thirty minutes. They just stretched their eight legs and went back to looking for food. They're the only animal we know that can take the full hit of space without a suit.

HostBut the sun’s rays out there are incredibly strong. They shred DNA like a hot wire through plastic. A glass shield or being dry doesn't sound like enough to stop that kind of deep damage to their blueprints.

GuestYou're right to be skeptical. Those rays are like tiny bullets that shred the code of life. But these water bears have another trick. They have a special protein we call a damage suppressor. Think of it like a suit of armor for their DNA. This protein physically wraps around the DNA and acts like a cushion. When those harsh rays hit the cell, the protein takes the hit instead of the code. It's like having a guard whose only job is to stand in front of the most important part of the cell and keep it safe. They even have ways to fix their code super fast once they wake up. They have these little worker proteins that scan for any cracks or breaks and stitch them back together in a few hours. It's a double layer of safety that most other living things just don't have.

HostIf it's just a special protein doing the work, it seems like we could just borrow it. Could we put that armor into our own cells and make ourselves space-proof?

GuestScientists have actually tried putting that armor protein into human cells in a lab, and it did make them stronger. But we're a lot more complicated than a water bear. We haven't figured out how to dry ourselves into a ball without dying. The real magic is how they stay in that paused state for so long. Some have been found in old museum samples, sitting dry for decades, and they still woke up. Even a crash landing on the moon doesn't stop them. A few years ago, a lander carrying thousands of these bears hit the moon at hundreds of miles an hour. They're likely still sitting there right now in the dust, tucked away in their little glass balls, waiting for the one drop of water that will bring them back to life.

HostThat dry moss on my garden wall feels a lot more like a fortress now that I know who's hiding inside it.