Somewhere in a Baltimore laboratory, a hardy bacterium was pressed between metal plates and struck by a fast-moving projectile, an echo of the violence that could hurl rock off a dying or living world. The question it answers is old and quietly hopeful: whether life might ride the debris of catastrophe from one planet to another, and whether a microbe could carry the story of its origin across the dark. The survival of most cells under pressures far beyond the ocean's deepest floor suggests that such a passage is not impossible. It also reminds us that as we reach toward Mars, we carry a respo
Lab Tests Show Hardy Microbes Can Survive Asteroid-Impact Shock, Fueling Debate on Interplanetary Life Transfer
We kept trying to kill it, but it was really hard to kill.
Mark
Why does it matter that a bacterium survived being shot with a gas gun?
Mimi
Because the launch was the big doubt. Martian rock is known to land on Earth, but nobody was sure anything alive could survive being thrown off Mars.
Luke
Survive in a lab, though. This is one bacterium, one kind of shock, and it's famously tough.
Mark
Why that one?
Mimi
Deinococcus radiodurans handles radiation, cold and dryness, and it has a thick shell and strong DNA repair. The researchers say hypothetical Martian life would likely share such traits.
Luke
Note the 'likely' and 'hypothetical.' We don't know there is life on Mars.
Mark
What were the numbers?
Mimi
Pressures of 1 to 3 gigapascals. Nearly all cells survived at 1.4, and about 60 percent at 2.4.
Luke
And big Mars impacts can reach near 5 for some debris, so the experiment covers only part of that range. The study says some microbes could survive a significant portion of it, not all of it.
Mark
What about the policy angle?
Mimi
Contamination rules for Mars missions and sample returns, and the possibility of ejecta reaching Phobos at lower pressures.
Luke
That's a suggested implication, not a rule change. Nothing here shows microbes survive the full trip through space.
El Pulso
- A gas gun fires projectiles at bacteria at speeds up to 300 mph, testing whether life could endure the force that launches rock off a planet.
- Deinococcus radiodurans, a microbe built to survive radiation and drought, keeps living through pressures more than ten times deeper than the Mariana Trench.
- At 2.4 gigapascals, roughly 60 percent of the cells survive, and the researchers keep firing harder because the bacteria refuse to die.
- The findings tug at planetary protection rules, raising alarms about contaminating Phobos and the samples scientists hope to bring home from Mars.
Somewhere in a Baltimore laboratory, a hardy bacterium was pressed between metal plates and struck by a fast-moving projectile, an echo of the violence that could hurl rock off a dying or living world. The question it answers is old and quietly hopeful: whether life might ride the debris of catastrophe from one planet to another, and whether a microbe could carry the story of its origin across the dark. The survival of most cells under pressures far beyond the ocean's deepest floor suggests that such a passage is not impossible. It also reminds us that as we reach toward Mars, we carry a responsibility to the worlds we may someday disturb.
At Johns Hopkins University, researchers sandwiched a layer of bacteria between metal plates and fired a projectile at it from a gas gun, reaching speeds of up to 300 mph. Their aim was to reproduce in miniature the blow of an asteroid striking Mars and sending rock into space. Martian meteorites have already reached Earth, but no one knew whether living things could survive the force needed to escape a planet at all.
The team chose Deinococcus radiodurans, a bacterium famous for enduring radiation, cold, and dryness. Its thick shell and powerful DNA repair make it a fitting candidate, and senior author K.T. Ramesh noted that any Martian life would likely share such traits, though no one yet knows whether it exists.
The shots produced pressures between 1 and 3 gigapascals, far beyond the Mariana Trench's floor. Nearly all cells survived 1.4 gigapascals, and about 60 percent endured 2.4. Lead author Lily Zhao admitted the team expected the microbes to die at the first pressure, but they kept firing harder, and the bacteria proved remarkably difficult to kill.
The results matter because large Martian impacts can subject debris to near 5 gigapascals, and the study suggests some microbes could endure much of that range. Zhao, half-joking, wondered whether humans might be Martians after all. Ramesh cautioned that the findings should make planetary protection rules more careful, since debris can reach moons like Phobos under gentler conditions. The team plans to test whether repeated impacts breed even hardier microbes and whether fungi can survive similar shocks.
In a lab at Johns Hopkins University, researchers sandwiched a layer of bacteria between metal plates and fired a projectile at it from a gas gun. The projectile traveled at up to 300 mph. The goal was to recreate, in miniature, the violence of an asteroid striking Mars and flinging rock into space.
The experiment addresses a long-standing idea called lithopanspermia, the proposal that life can move between worlds inside meteorites and planetary debris. Scientists already know that Martian meteorites have reached Earth. What has been unclear is whether living organisms could survive the force needed to launch them off a planet in the first place.
The team chose Deinococcus radiodurans, a bacterium known for withstanding extreme radiation, cold, and dryness. It has a thick outer shell and strong DNA repair mechanisms. Senior author K.T. Ramesh said that if life exists on Mars, it is likely to have similar abilities, though he noted that no one yet knows whether it does.
The shots generated pressures between 1 and 3 gigapascals. For scale, the pressure at the bottom of the Mariana Trench is about 0.1 gigapascals, so even the gentlest shot in the experiment exceeded it more than tenfold.
The bacteria survived nearly all the tests at 1.4 gigapascals, and about 60 percent survived at 2.4 gigapascals. At lower pressures the cells showed no visible damage. At higher pressures some membranes ruptured and internal structures were affected, yet many microbes stayed viable. Lead author Lily Zhao said the team expected the organisms to be dead at the first pressure. They kept firing faster and faster, she said, and the bacteria were really hard to kill.
Those numbers matter because large asteroid impacts on Mars can subject some debris to pressures near 5 gigapascals, although not every fragment feels the same forces. The findings suggest that at least some microbes could survive a significant portion of that range. Zhao said the work shows life can survive large-scale impact and ejection, and so could potentially move between planets. She added, half-joking, "Maybe we're Martians!"
The results may also bear on planetary protection policy. Space agencies impose strict contamination controls when sending spacecraft to Mars and when returning samples to Earth. Mars ejecta can also reach its moons, such as Phobos, under lower pressures than are needed to escape toward Earth. Ramesh said that researchers might need to be very careful about which planets we visit.
The team plans further work: testing whether repeated impacts could select for even hardier microbes, and whether other organisms, including fungi, can survive similar shocks. The study was published in PNAS Nexus.
Citas Notables
We have shown that it is possible for life to survive large-scale impact and ejection.— Lily Zhao, lead author
We might need to be very careful about which planets we visit.— K.T. Ramesh, senior author
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