Scientists squeeze microbes into steel ‘sandwiches’ and make major discovery about life in the universe

A new laboratory study has shown that “extremophile” bacteria can withstand an asteroid impact strong enough to send it flying into space. This suggests that potential alien life could spread between worlds through collisions with space rocks.

In the new study, published March 3 in the journal PNAS Nexus, researchers sandwiched Deinococcus radiodurans, a type of bacteria that has been shown to survive in space for many years, between two steel plates. They then crushed the “sandwich” very hard and quickly to simulate an asteroid hitting a planet, and measured how many microorganisms survived.

The pressure to crush the sandwich was chosen based on the pressure required for an asteroid impacting Mars to launch microorganisms and planetary debris into space. The team tested pressures between 1.4 and 2.9 gigapascals (GPa). This is approximately 14,000 to 29,000 times the Earth’s atmospheric pressure at sea level. Approximately 60% of the microorganisms survived a shock of 2.4 GPa, and up to 95% survived when the pressure was lowered to 1.4 GPa.

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In most previous studies testing such scenarios, microbial survival rates were orders of magnitude lower. The study authors theorized that this may be because the microorganisms tested in the new study were different. More elastic. It can withstand extreme radiation exposure, desiccation (extreme dryness), and high temperatures.

extreme forms of life

The researchers decided to test D. radiodurans because it can withstand the cold, empty vacuum of space. A 2020 study found that D. radiodurans survived three years of exposure to space while attached to the outside of the International Space Station, which is not a hospitable place for life. (Moss doesn’t seem to mind)

The researchers also looked at how the microbes recovered after the shock by culturing the cells at 98.6 degrees Fahrenheit (37 degrees Celsius) for several hours and measuring which genes they expressed. They found that after being subjected to higher-pressure shocks (enough to damage cell membranes), microbes prioritized genes involved in repairing cell damage rather than building new cells. They also took in more iron and repaired their DNA.

Understanding how life moves between planetary bodies is important for sample return missions, the study authors note in their paper. For example, samples returned from Mars must go through strict procedures to prevent Martian microbes from potentially flying to Earth and contaminating it. If asteroid impacts can transport microorganisms to other parts of the solar system, samples returned from other locations may also require additional precautions to prevent contamination.

Additionally, this research shows that certain life forms can survive being violently thrown into space. This could affect where and how we look for life in the solar system.