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Tardigrades are almost bulletproof, scientists discover

Published May 20th, 2021 11:43PM EDT
tardigrades moon
Image: NASA

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Tardigrades — those microscopic organisms that have been found to withstand extreme radiation, the vacuum of space, and temperatures that would turn most other organisms into literal popsicles — are a true wonder of nature. They seem to be virtually indestructible, and in a highly-anticipated 2019 mission by Israel, they were sent to the Moon. Unfortunately for the country and scientists working on the mission, the Moon lander crashed and was completely destroyed. The tardigrades, however, well we aren’t quite sure what happened to them, but scientists are eager to find out.

Tardigrades, also called “water bears,” are so ridiculously hardy that researchers think they may have survived the high-speed collision between the lander and the Moon’s surface. To test that theory, a team led by a Ph.D. student from London’s Queen Mary University conceived of an experiment where the microscopic creatures would be shot out of a “science gun,” as it were.

The gun is unlike a conventional firearm in that it uses a two-stage system to propel projectiles at extremely high speeds. The projectiles reach speeds greater than bullets fire from a typical gun, and the extreme impact of the projectiles against a target is a better simulation for the kind of extremes the tardigrades might have endured.

Before being fired from the gun, the tardigrades were subjected to freezing temperatures. This triggered a hibernation state that reduces their metabolism to a tiny fraction of what it would be under normal conditions. Then, the tardigrades were loaded into nylon bullets in groups of 2 to 4. The researchers fired those bullets at sand targets a short distance away and observed whether or not the tiny creatures survived the intense pressure changes of the initial shot as well as impact with the target.

The scientists shot the projectiles at different speeds, gradually increasing the velocity with each subsequent shot. What they found was that tardigrades are indeed capable of enduring a bullet impact, but only up to a point. The tardigrades were capable of enduring shots of up to roughly 900 meters per second. To put that in perspective, a 9mm handgun round can be expected to travel at speeds of around 400 meters per second. Meanwhile, most 5.56x45mm rounds fired from a rifle will travel somewhere between 850 and 900 meters per second.

So, the tardigrades were capable of enduring impacts akin to that of a rifle round, which is pretty impressive. Unfortunately for anyone who likes to imagine the tiny water bears surviving their brush with death on the surface of the Moon, the impact of the lander with the lunar surface would have subjected the creatures to a shock of much greater intensity. The researchers feel comfortable in stating that none of the tardigrades could have survived the impact. Bummer.