Researchers in Japan have provided more evidence supporting the theory that all life on Earth could have sprung from bacteria that landed on the planet from outer space.
The evidence comes from an experiment that was conducted on the International Space Station (ISS), the results of which were published Wednesday in the science journal Frontiers in Biology.
The researchers placed bacteria samples in exposure panels outside the ISS and left them there for three years. They said they when the samples were examined, the bacteria at the surface had died off but formed a protective layer for the bacteria beneath the surface, ensuring the survival of the rest.
The researchers said that based on the data they collected, a bacterial colony measuring approximately 1 millimeter in diameter could have survived for up to eight years in outer space.
If so, then a bacterial colony could theoretically survive the journey from Earth to Mars, or vice versa, which would take several months or years, depending on the trajectory.
The study provides important evidence for a theory known as panspermia, which suggests that life didn’t originate on Earth, but instead began elsewhere in the cosmos and was transported to the planet through interstellar objects such as asteroids that smashed into Earth billions of years ago.
The researchers said their experiment provided for the first time an estimate of the survival rate of bacteria in outer space. Previous experiments suggested that bacteria might survive in space while being shielded beneath the surface of a meteor or asteroid. But the scientists said this was the first experiment to test bacteria in the form of an aggregate or cluster.
They also said the results suggested life might be much more common in the universe than previously thought.