A bacterium renowned for its resilience has survived pressures mimicking the force of an asteroid impact on Mars, bolstering the theory that life could potentially travel between planets, according to research published today in PNAS Nexus.
Researchers at Johns Hopkins University and collaborating institutions subjected Deinococcus radiodurans to pressures reaching 3 gigapascals – equivalent to 30,000 times atmospheric pressure – simulating the conditions experienced during ejection from Mars following a major impact event. The experiment involved sandwiching the microbes between steel plates and then impacting the structure with a third plate, replicating the shockwave of an asteroid strike. Remarkably, a significant proportion of the bacteria survived.
“Life might actually survive being ejected from one planet and moving to another,” said K.T. Ramesh, an engineer at Johns Hopkins University who led the study. “This is a really big deal that changes the way you think about the question of how life begins and how life began on Earth.”
Deinococcus radiodurans is already known for its ability to withstand extreme radiation and desiccation, making it a prime candidate for studying the potential for interplanetary survival. The current study builds on that understanding by demonstrating its capacity to endure the immense pressures associated with impact ejection. Researchers analyzed gene expression in the bacteria at varying pressure levels, finding that those exposed to 2.4 GPa exhibited ruptured cell membranes, yet approximately 60% of the microbes remained viable. The bacterium’s cell envelope structure is believed to contribute to this survival rate.
The research team observed that the surviving bacteria prioritized the repair of cellular damage following the impact, suggesting a robust and efficient DNA repair mechanism. This finding, detailed in the PNAS Nexus publication, indicates that microorganisms may be capable of surviving conditions far more extreme than previously assumed.
Impact craters are prevalent throughout the solar system, particularly on Mars, and evidence suggests that asteroid strikes can launch material into space. Martian meteorites have already been discovered on Earth, demonstrating the feasibility of interplanetary transfer of rock. This new research suggests that viable microorganisms could also be included in such debris, potentially seeding other planets with life – a concept known as lithopanspermia.
The study has implications for planetary protection protocols and the planning of future space missions, raising questions about the potential for forward contamination – the introduction of terrestrial life to other planets.