Tiny life forms tucked into debris from an asteroid hit could catapult to other planets – including Earth – and survive, a new Johns Hopkins University study finds.
By Keith Cowing
The work demonstrates that a certain hardy bacterium easily withstands extreme pressure comparable to an ejection from Mars after an asteroid hit, as well as the inhospitable conditions it would face during the ensuing interplanetary journey.
The study, published today in PNAS Nexus, suggests that microorganisms can survive remarkably more extreme conditions than expected, and raises questions about origins of life. The work also has significant implications for planetary protection and space missions.
“Life might actually survive being ejected from one planet and moving to another,” said senior author K.T. Ramesh. “This is a really big deal that changes the way you think about the question of how life begins and how life began on Earth.”
To study how a microorganism would realistically handle the stress of a planetary ejection, the team devised a way to replicate the pressure and a singular biological model. The experiment simulated the pressure of an asteroid strike and ejection from Mars by sandwiching the microbe between metal plates and then firing a projectile at it from a gas gun. The projectile hit the plates at speeds up to 300 mph, generating 1 to 3 Gigapascals of pressure. — Johns Hopkins University
Impact craters cover the surfaces of most bodies in the solar system. Mars, a planet that could harbor life, is one of the most cratered celestial bodies. We know asteroid strikes can launch material across space—and Martian meteorites have been found on Earth.
However, scientists have long wondered if life forms could also be launched from an asteroid impact. Tucked inside ejected debris, they might land on another planet—a theory called the lithopanspermia hypothesis.
Previous experiments to test the theory have been inconclusive, and targeted organisms widely found on Earth, rather than a life form that would suit the extreme environments of other planets.
To study how a microorganism would realistically handle the stress of a planetary ejection, the team devised a way to replicate the pressure and a singular biological model.
