A new study recently found that water bears can even survive an impact 2.4 times the speed of sound (825 m/s).
The ability to survive near absolute zero, to withstand the heat that boils water, to not care about the vacuum of space, and to lethal radiation doses to humans is “a piece of cake” for them – this is called “” “The strongest creature on the surface” of the tardigrade (tardigrade), commonly known as the water bear (water bear).
In 2019, Israel launched its lunar space mission Genesis. The mission, originally planned for a soft landing on the lunar surface, has high hopes because, if successful, it will be the first privately funded probe to land on the moon, and Israel will be the fourth in the world to have a probe on the moon. The country that made a soft landing on the lunar surface.
But unfortunately, just minutes before it was ready to land on the moon, the probe lost contact with Earth and crashed into the moon out of control.
Originally a regrettable failure, it then raised some additional concerns. Because the probe also carried a group of special “passengers”, which fell on the surface of the moon together in this impact event. These “passengers” are water bears.
The fall of tardigrades has raised concerns about contamination of the lunar surface due to their super survivability. Some scientists believe the creature must be capable of surviving an impact event, while many more are curious to know what the conditions are for these tardigrades.
Inspired by the incident, a team of scientists conducted experiments that allowed the tiny creature to be struck at the speed of a bullet. To a certain extent, the animal does survive. The experiments also put new constraints on their ability to survive in space and the possibility of nurturing life on other planets.
The researchers wanted to conduct the experiments in a relatively ethical manner. After feeding about 20 tardigrades with moss and water, they froze the critters for 48 hours, putting them into hibernation, a state known as a “tun.” In this state, the tardigrade’s metabolism was reduced to 0.1% of its normal activity.
They then loaded 2 to 4 tardigrades into a hollow nylon bullet and fired a secondary light gas cannon at increasing speeds, shooting the bullet into a sandy target several meters away. The secondary light gas gun is a tool used in physics experiments, which allows the bullet to reach a fairly high initial velocity.
In experiments, scientists found that the creatures could withstand an impact of 825 meters per second and survive with an instantaneous shock pressure of up to 1.01GPa; but when the speed reached 901 meters per second (instant shock pressure of 1.14 GPa), they would Couldn’t survive it and would turn into a mush in an accident.
Some tardigrades in the experiment: (a) (b) tardigrades before the experiment; (c) showing the tardigrades that survived the impact experiment at 728 meters per second; (d) 901 per second Water bear fragments left after Mi’s impact experiment.
Scientists believe that this result basically helps us confirm that the tardigrades on the “Genesis” should be unlikely to survive. Although the lander is thought to have crashed at a speed of a few hundred meters per second, the shock pressure of its metal frame hitting the ground should be well above 1.14GPa.
The study also puts new constraints on panspermia. This theory holds that some life forms may have been transferred between different planets. After a planet or moon was hit, the debris and “life stowaways” were splashed into space and eventually reached new worlds, allowing life to spread across the universe.
But some scientists think the study is a good example of how complex multicellular animals are not so easily transferred. In other words, the earth is like a biogeographic island to animals, and animals are flightless birds on the island, trapped here.
But others say that panspecies is indeed “difficult to achieve”, but not completely impossible. Meteorites typically hit the Earth at speeds exceeding 11 kilometers per second. On Mars, they can hit at least 8 kilometers per second. These speeds are indeed well above the threshold for tardigrades to survive.
However, some parts of the meteorite may experience a lower shock pressure when it hits, and there may be a “silver life” for the tardigrades. Additionally, according to previous research, some microbes can withstand higher-intensity impacts compared to water bears, and even have a chance of surviving an impact of 5 kilometers per second.
