If microorganisms could survive a journey through space inside meteoroids, could life from Earth be transferred to planets in other solar systems—or even vice versa? A new study suggests the possibility is much higher than scientists once thought.
Using computer simulations involving slow-moving rocks, scientists from Princeton University, the University of Arizona, and the Centro de Astrobiología (CAB) in Spain concluded that Earth could have exchanged rocks trillions of times with planets from other planetary systems during the solar system’s infancy.
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At the time—several billion years ago—the sun would have been in its native star cluster, with Earth and nearby planetary systems under heavy meteorite bombardment, said study co-author Amaya Moro-Martin, an astrophysicist at CAB.
Scientists had previously considered the possibility that meteorites could escape from our solar system and land on a terrestrial planet in another system. But they had concluded that the chances were extremely slim because of the speeds of the objects involved.
"Everyone assumed the rocks would be ejected very fast—so fast they couldn’t be captured by the next star. They were flying right by," said study leader Edward Belbruno, a Princeton mathematician.