Researchers from Kent tested how well tardigrades can withstand the shock pressure that an asteroid collision can cause. Thus, scientists are testing the theory of panspermia. Astrobiology magazine writes about this.
Tardigrades are some of the most complex life forms ever discovered on Earth. Scientists have suggested that they (or similar organisms) can sow life in space by “hitchhiking” on asteroids. Researchers have now tested this hypothesis by firing tardigrades with a gas pistol into the sand and seeing how well they survived.
Tardigrades, when faced with harsh environmental conditions, dry out and curl up into a protective ball called a vat, allowing them to survive until conditions become more favorable again. In doing so, they have been observed to survive at boiling and freezing temperatures, intense radiation, crushing pressures similar to those found at the bottom of the deep sea, and are even capable of traveling into space.
Therefore, tardigrades were considered candidates for panspermia, a hypothesis that suggests that life could spread between planets and moons via asteroids.
For their work, the team of scientists froze samples of tardigrades for 48 hours, causing them to take the form of a protective vat. They then loaded the samples into a nylon casing and fired a light gas pistol into the sand. Impact velocities and shock pressures were measured, and then the tardigrades were collected for examination of the injuries received.
The researchers determined the upper limit for their survival in this scenario – an impact speed of 3240 km/h, which creates a pressure surge of 1.14 gigapascals (GPa). The maximum speed at which 100% of the tardigrades survived was 2621 km / h, while about 60% continued to withstand impacts up to 2970 km/h.
The team noticed that it took up to 36 hours for the surviving tardigrades to emerge from the vat state and start moving again – much longer than the control group, which was frozen and then thawed but did not pass the test. It took them 8-9 hours to recover.
The researchers say that most asteroid impacts will create pressure too high for tardigrades, but some of the impacts are slower, within an acceptable range. For example, up to a third of asteroid collisions on the Moon can be suitable for tardigrades to survive. These people, perhaps, have already accidentally checked during the crash of the lander “Bereshit” in 2019, on which there were frozen tardigrades. How well they handle the new situation is another matter.
The team also claims that these results can be used to test whether tardigrades or other similar life forms live on other worlds in our solar system. The icy moons Europa and Enceladus have underground oceans potentially harboring microorganisms, and we could find evidence of life by testing the jets of water they throw into space through cracks in the ice shell.