It proves quite challenging for humans to depart from Earth. This endeavor necessitates robust rockets and spacecraft engineered to sustain the extremely narrow window of conditions required for our very existence. For bacteria, the scenario looks decidedly different. Although microbes haven’t mastered rocketry, new findings propose they might not need such technology to traverse interplanetary distances. Simply possessing resilience and awaiting an impact with an asteroid could suffice for them. The outcomes of this novel investigation have been documented in the journal PNAS Nexus.
The concept of microbes spreading throughout the Solar System facilitated by asteroids is not new, yet this recent research furnished crucial insights into the capacity of one specific extremophile, Deinococcus radiodurans, to withstand intense pressure corresponding to an actual asteroid collision.
“Our objective was to determine whether life can endure planetary-scale impacts, specifically the dynamically induced high pressure associated with such massive strikes,” explained study co-author Lili Zhao from Johns Hopkins University. “Consequently, we ‘shot’ some extremophiles to observe their survival rate. We discovered they survived with an astonishingly high frequency… something previously undocumented in the scientific literature.”
The research team selected an extremophile originating from the high-altitude deserts of Chile, an organism adept at surviving some of Earth’s most hostile environments: extreme cold, desiccation, and intense radiation. These conditions closely mimic the baseline state on Mars, though even under its harshest conditions, Earth remains a comparative haven versus the Red Planet.
Nevertheless, the microorganism was subjected to pressures many times greater than those found at the bottom of the Mariana Trench, which reaches about 0.1 gigapascals. At 1.4 gigapascals, the bacteria survived nearly every trial without cellular damage. At 2.4 gigapascals, roughly 60 percent endured, albeit with some instances of membrane ruptures and internal structural damage.
It is remarkable how nature has adapted to these rigorous environments.
“When we initiated this project, our curiosity lay in defining the limits of life,” stated co-author K.T. Ramesh, also affiliated with Johns Hopkins University. “How far can tenacity extend regarding survival under such extreme mechanical stresses?”
The team specifically targeted conditions comparable to those on Mars, which dictated the choice of this particular extremophile. However, the resulting data has broader implications—asteroid impacts on Earth could have ejected microbial stowaways to vast reaches of the Solar System. While space rocks might more readily travel inward over time, it is plausible that they have propagated far beyond. Life may have dispersed from Earth or originated elsewhere before reaching us.
Currently, the investigators are examining other bacterial species to assess their performance under similar duress.
“We are realizing that these organisms are far more robust than our prior assumptions suggested,” Ramesh continued. “Every time we introduce a new environmental extreme—first cold, then desiccation, radiation, high temperature, static high pressure, and now dynamic high pressure—we locate organisms that persist. Nature’s capacity for adaptation to these situations is astonishing. In our view, this strongly indicates that life is significantly more resilient than we previously believed!”
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