A laboratory experiment found that a particularly resistant bacterium,Deinococcus radiodurans , capable of surviving enormous pressures similar to those created when an asteroid hits Mars – a finding that strengthens the possibility that life can travel between planets
A new study suggests an intriguing possibility: Bacteria may survive the massive shockwave created when an asteroid hits Mars and hurls rocks into space. If so, it's possible that microbial life could travel between planets by hitching a ride in rock fragments ejected by cosmic impacts.
The study, published in the journal PNAS Nexus, examined the resistance of the bacterium Deinococcus radiodurans, which is considered one of the most resistant organisms known to science.
The cratered, ridged surfaces of the Moon and Mars suggest that asteroid impacts were common throughout the history of the solar system. These impacts not only shaped the surfaces of planets and moons, but also likely ejected large amounts of rock and planetary material into space. If microorganisms can survive such a process, they may be able to travel between worlds.
An experiment simulating an asteroid impact
To test this possibility, a team of researchers led by Lily Zhao and KT Ramesh conducted an experiment that simulated the extreme shock that a bacterium might experience when a rock is ejected from a planet following an asteroid impact.
As part of the experiment, bacteria were placedDeinococcus radiodurans Between two steel plates, and then a third plate hit them at high speed. The impact created pressures of up to 3 gigapascals – a pressure 30,000 times higher than atmospheric pressure on Earth.
Such pressures simulate the sudden, enormous compression that would occur when rocks are torn off the surface of Mars by an asteroid impact and thrown into space.
Extraordinary resistance of the bacteria
The bacteria tested are already known for their ability to survive extremely extreme conditions, including intense radiation and near-total desiccation. Due to these properties, they are considered a prime candidate for survival in space conditions.
During the experiment, the researchers examined which genes were activated in the bacterial cells as the stress gradually increased. This allowed them to monitor the level of biological stress and analyze how the cells coped with the damage they were inflicting.
When the pressure reached 2.4 gigapascals, some cells already showed ruptures in their cell membranes. Despite this, about 60% of the bacteria survived the extreme conditions. The researchers believe that the bacteria's strong cell envelope plays a key role in protecting them from such extreme compression.
Quick repair of the damage caused by the impact
Analysis of the genetic activity of the surviving bacteria revealed that immediately after the shock they activated cellular repair mechanisms. Their genetic transcription patterns showed that repairing damage to membranes and cellular systems becomes a top priority after the injury.
The ability to quickly switch to a damage repair mode may be a crucial factor that allows microorganisms to survive extreme events such as asteroid impacts.
A hint at the transfer of life between planets
The findings suggest that microorganisms may be more resilient than previously thought. If bacteria can survive the violent launch into space following an asteroid impact, it is possible that life could travel between planets while trapped within fragments of rock ejected from one planet and impacting another.
This idea, known as panspermia, suggests that life may have spread throughout the solar system and beyond via planetary material moving between worlds following cosmic collisions.
The new study does not prove that life actually passed between Mars and Earth, but it shows that at least from a physical and biological perspective, this scenario may be possible.
for the scientific article DOI: 10.1093/pnasnexus/pgag018
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