Lithopanspermia

A recent study suggests that earthly microbes just might have hitchhiked their way across the solar system. If so, then perhaps they survived long enough to “seed” some of the moons of the outer planets with life.

Scientists know that material can be blasted off one planet and land on another — they’ve seen the proof in meteorites that came from Mars. So a team of researchers at Penn State tried to find out whether chunks of rock blasted off of Earth could find their way to other worlds — especially to Europa, one of the largest moons of Jupiter.
Europa appears to have the ingredients necessary to support life: an ocean of liquid water beneath its icy crust, a source of energy, and the right chemistry. So if life from Earth or even Mars landed on Europa, perhaps it could survive there.
The team’s simulations looked at Earth rocks that were large enough to protect microscopic organisms from the rigors of the trip. They showed that perhaps a half-dozen of these big boulders could have