The adorable, microscopic, crystal-pooping, nigh-invulnerable water bears known as tardigrades have another wonderful superlative to add their resume: living bullets.
According to a new study from the journal of Astrobiology, scientists loaded tardigrades into canisters and shot them out of gas-powered guns at extreme velocities to see how they fared. Which is how you get wild passages like this:
The animals used herein were the tardigrade species Hypsibius dujardini, which were handled according to the ethical rules for invertebrates with the consent of the departmental ethics officer. The tardigrades were fed mineral water and moss (see Fig. 1a, 1b). They were fired from a two-stage light gas gun (Burchell et al., 1999; Hibbert et al., 2017) at sand targets in a vacuum chamber. Prior to shooting, two or three tardigrades were loaded into a water-filled shaft in a nylon sabot (the number was measured in each case). The sabot was then frozen for 48 h so that the tardigrades were in a tun state during the shot. The sabot was then placed in the gun and fired at normal incidence into the sand. The whole sabot impacted the target in each shot. Impact speeds were measured in each shot to better than ±1% using two laser light stations mounted transverse to the direction of flight and focused onto photodiodes. The signals from the photodiodes, combined with their known separation (499 mm), provided the speed.
As it turned out, the tardigrades could survive the impact up to 2,000 miles per hour, or the equivalent of 1.14 gigapascals (GPa). "Above that, they just mush," one of the scientists involved told Science Magazine.
Tardigrades have been previously known to survive inside of volcanoes, in the vacuum of space, and in underground Antarctic lakes where the pressure is about six times that of the deepest part of Earth's oceans. They can even return to full normal functioning after being frozen for three decades.
But the impetus for this particular experiment was a 2019 Israeli space mission where someone smuggled some secret tardigrades on board … before crashing into the moon. So the tardigrade gun test was designed to help determine whether or not those tardigrades could have possibly survived their disastrous Lunar stranding.
Spoiler alert, dear reader: those castaway tardigrades are mush.
Tardigrade Survival Limits in High-Speed Impacts—Implications for Panspermia and Collection of Samples from Plumes Emitted by Ice Worlds [Alejandra Traspas and Mark J. Burchell / Astrobiology]
Hardy water bears survive bullet impacts—up to a point [Jonathan O'Callaghan / Science]
Image: Eden, Janine and Jim / Flickr (CC-BY-SA 2.0)