According to reporting on a new study in the International Journal of Astrobiology, even the most indestructible microscopic animals in existence, tardigrades, have their limits. That limit is the dirt on Mars.Researchers at Pennsylvania State University exposed two species of tardigrade to lab-made simulations of Martian soil, aka regolith, the technical term for the loose collection of dust and busted rocks that collects on the surface of celestial bodies like planets and moons.Tardigrades are famous for a couple of things. First and foremost, they are simultaneously adorable and freaky. Secondly, they are known for being able to survive damn near anything space can throw at them — radiation, dehydration, extreme temperatures, the vacuum of space itself. They’re so good at adapting that they can enter a dried-out “tun” state and deploy specialized proteins that protect their DNA.Tardigrades Can’t Survive Mars. Specifically, Martian Dirt.Theoretically, if anything we can find here on earth would be able to handle the harshness of Mars, it would be a tardigrade. And yet, when researchers placed them in two simulations of regolith, called MGS-1 and OUCM-1, they started dying fast. The MGS-1 mix killed off freshwater tardigrades within two days, with only the sturdier land version of a tardigrade lasting a bit longer. The ones in the OUCM-1 soil struggled, despite this regolith being less harsh. A control group of tardigrades in plain old Earth sand remained healthy.Clearly, tardigrades cannot handle Mars dirt… That is, until the researchers moistened it with just a bit of water. Suddenly, their survival rates improved dramatically. Their activity levels are to look like the ones in the Earth sand control group. Researchers aren’t exactly sure what’s going on in the unwashed simulant sand, but whatever it was appeared to be lethal until it got a thorough soaking.Lead researcher Corien Bakermans said that on one hand, toxic regolith could act as a built-in planetary defense system, limiting contamination from Earth organisms, which is a core goal of planetary protection. On the other hand, if humans hope to grow crops on Mars, the soil may require treatment first.The study didn’t take the wide variety of harsh elements on Mars into account, like its radiation, atmospheric pressure, or extreme temperature swings, but it does provide us with a solid base to start working from if you want to one day, possibly decades from now, expand human life beyond the Earth. If we want to farm on Mars, thanks to this research, we now know that we might need to start by hosing it down first.The post Scientists Finally Found Something That Can Kill a Tardigrade appeared first on VICE.