Martian microbes may survive asteroid ejection and reach Earth

A Johns Hopkins team reported that Deinococcus radiodurans survived lab impacts producing pressures similar to asteroid strikes, with survival near 95% at 1.4 GPa, about 60% at 2.4 GPa and under 10% at 2.9 GPa.

Researchers tested whether microbes could survive forces like those in asteroid impacts and found notable resilience in a hardy bacterium. The experiments were done at Johns Hopkins and were published in Proceedings of the National Academy of Sciences NEXUS. The work explores a long-standing idea called lithopanspermia, which proposes that microbes could move between planets on rocks ejected by impacts. That idea remains unsubstantiated, but the new lab results address one part of the question: survival during ejection. Key findings: - The team used the bacterium Deinococcus radiodurans, known for resistance to radiation, dehydration and chemical stress. - Samples were sandwiched between steel plates while a metal plate was fired at speeds up to about 300 miles per hour to produce impact pressures. - Generated pressures ranged roughly from 1 to 3 gigapascals, comparable to pressures associated with some asteroid impacts. - Survival rates averaged about 95% at 1.4 GPa, about 60% at 2.4 GPa, and just under 10% at 2.9 GPa. - The experimental apparatus began to fail before the researchers reached an impact pressure that fully eliminated the microbes. Summary: The experiments show that at least one very hardy bacterium can persist through pressures like those produced in asteroid ejection events, which bears on questions about whether material blasted from Mars could carry viable microbes. The authors plan to test other kinds of microorganisms in future experiments to broaden the findings and probe how general the observed resistance may be.