A new study, published in PNAS Nexus and led by K.T. Ramesh, tested whether microbes can survive the forces of an asteroid strike and the harsh conditions of space. The researchers focused on the desert bacterium Deinococcus radiodurans, known for resisting cold, dryness and intense radiation because it has a thick shell and strong cell-repair ability.
To mimic ejection from a planet like Mars, the team sandwiched the bacterium between metal plates and fired a projectile with a gas gun at speeds up to 300 mph. Impacts generated pressures between 1 and 3 gigapascals. The bacteria survived nearly every test at 1.4 gigapascals and about 60% survived at 2.4 gigapascals. At higher pressures some cells showed ruptured membranes and internal damage; in one test the steel setup failed before the bacteria died.
The findings support the idea of lithopanspermia—transfer of life by rock—and have implications for planetary protection rules and sample handling on missions.
Difficult words
- microbe — very small living organism, often single-celledmicrobes
- bacterium — single-celled microorganism found in environments
- ejection — forced leaving or throwing out from a place
- mimic — to copy conditions or behaviour for testing
- gigapascal — unit of pressure equal to one billion pascalsgigapascals
- lithopanspermia — hypothesis that life moves between planets inside rocks
- implication — possible result or effect of an action or factimplications
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Discussion questions
- What do the study results suggest about the possibility of life moving between planets? Explain in two sentences.
- How might these findings affect rules for handling samples on space missions? Give one clear reason.
- Would you be surprised if microbes arrived on Earth inside rocks from another planet? Why or why not?
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