Tough microbe study backs idea of life moving between planets

by Clarence Oxford
Los Angeles CA (SPX) Mar 29, 2026
Tiny life forms embedded in debris blasted off a planet by an asteroid impact could travel through space and arrive on another world still alive, according to new experiments by Johns Hopkins University researchers. The work bolsters the lithopanspermia hypothesis, which proposes that impacts can eject rock fragments carrying microorganisms that later seed life on other planetary bodies.

The study, published in PNAS Nexus, focused on Deinococcus radiodurans, a desert bacterium from the high deserts of Chile known for surviving extreme cold, dryness, and intense radiation. With its thick outer shell and exceptional DNA repair abilities, the microbe serves as a realistic stand-in for potential life that might exist in harsh environments on Mars or other planets.

To simulate the conditions of an asteroid strike and the violent ejection of material from Mars, the team sandwiched the bacteria between metal plates and fired a projectile at the stack using a gas gun. The impact drove pressures of 1 to 3 gigapascals while the projectile reached speeds up to about 300 miles per hour, reproducing the intense mechanical shock a rock would experience as it is hurled off a planetary surface.

For comparison, the pressure at the bottom of the Mariana Trench, the deepest point in Earths oceans, is roughly one tenth of a gigapascal. Even the lowest pressures in the Johns Hopkins experiments exceeded that by more than a factor of ten, pushing the limits of what many scientists previously thought living cells could tolerate.

After each shot, the researchers checked how many microbes survived and examined their genetic material for signs of damage and repair. The bacterium proved extremely resilient, surviving nearly every test at around 1.4 gigapascals and about 60 percent of the time at approximately 2.4 gigapascals. At the lower pressures, cells showed no visible structural damage, while at higher pressures some exhibited ruptured membranes and internal damage but still included survivors.

Lead author Lily Zhao said the team kept increasing the impact speed in an effort to kill the cells outright but found them much tougher than expected. In contrast, the hardware used in the tests eventually failed, with the steel configuration that held the plates falling apart before the entire microbial population could be destroyed.

On Mars, fragments launched by asteroid impacts are thought to encounter a wide range of pressures, with typical values around 5 gigapascals and some pieces experiencing even higher stresses. The new results show that the test microbe can tolerate nearly 3 gigapascals, significantly above levels previously considered survivable and within the range associated with material ejected from the Martian surface.

Senior author K.T. Ramesh said the findings indicate that life can survive large scale impact and ejection events, opening the door to the possibility that microorganisms could move between planets. The work also suggests that life on Earth itself might have originated elsewhere in the solar system before arriving here on impact debris.

The prospect of living material traveling between planetary bodies has direct implications for planetary protection policies that govern space missions. Current protocols place strict constraints on missions to worlds considered potentially habitable, such as Mars, to avoid contaminating them with Earth life, and on sample return missions to prevent uncontained delivery of extraterrestrial organisms to Earth.

Because the new study indicates that microbes could survive conditions associated with ejecta escaping Mars, the authors argue that materials reaching nearby bodies, including its two moons, may also be capable of carrying viable life. Phobos, which orbits close to Mars, is likely to receive Martian debris that experiences lower peak pressures than ejecta destined for Earth, making it a particularly important target when considering contamination risks.

The team notes that this broader view of survivable impact conditions may require a reassessment of how planetary protection rules are applied, especially for destinations that are currently less restricted but could still accumulate biologically interesting material from Mars. Ramesh said the results underline the need for caution in choosing planetary targets and designing mission architectures that minimize unintended biological transfer.

Looking ahead, the researchers plan to test whether repeated impactlike shocks select for even hardier bacterial populations or drive adaptive changes that improve survival under extreme mechanical stress. They also intend to expand their experiments to other organisms, including fungi, to see whether similar resilience is common across different branches of life or a special feature of only a few extreme microbes.

Research Report:Extremophile survives the transient pressures associated with impact-induced ejection from Mars