Earth life may have begun on Mars, study suggests microbes survive impact pressures

A lab study found Deinococcus radiodurans survived pressures up to about 3 gigapascals—conditions similar to those during asteroid ejecta—and the authors say this finding supports the idea that microbes could survive interplanetary transfer.

A recent laboratory study examined how the bacterium Deinococcus radiodurans responded to pressures like those produced when asteroid impacts eject rock into space. Researchers placed bacterial samples between steel plates and used a gas-powered projectile to generate pressures between about 1 and 3 gigapascals. Many cells survived the higher pressures, and the experiment was reported in the journal PNAS Nexus. The results have prompted discussion about whether such survival could affect ideas about the origin and spread of life in the solar system. Key findings: - Researchers simulated impact pressures by sandwiching D. radiodurans samples between steel plates and firing a projectile at roughly 300 mph, producing pressures in the 1–3 gigapascal range. - Nearly all microbes survived impacts around 1.4 gigapascals, and about 60% remained alive at roughly 2.4 gigapascals. - At lower pressures cells showed no clear damage; at higher pressures some samples showed ruptured membranes and internal damage. - Gene activity associated with DNA repair and membrane maintenance increased as pressure rose. - Authors say the results lend support to the lithopanspermia idea that life could spread on rocks between planets, but the theory remains unproven and clear evidence of life on Mars is still lacking. Summary: The study indicates that at least one exceptionally resilient bacterium can survive pressures similar to those generated during asteroid ejection, a result that has prompted scientists to revisit questions about interplanetary transfer of life and related planetary protection discussions. Undetermined at this time.