Could Earth have seeded Jupiter's moon Europa with bacterial life, where it could have taken hold in Europa's ocean and perhaps evolved into something more? That's the hypothesis of a new paper in the International Journal of Astrobiology by Zaza Osmanov of the Free University of Tbilisi in Georgia.
Osmanov calculates the chance that dust particles containing living bacteria were ejected from Earth's gravitational well and traveled to Jupiter's icy moon Europa, where they could have landed undestroyed and made their way through cracks in Europa's ice, beneath which lies a vast sea that scientists believe could harbor life.
The possibility of panspermia, bringing simple life to Earth from elsewhere in the universe, has been discussed for decades. Dust, meteoroids, asteroids and comets might all have contained life forms as they crashed into Earth.
The hypothesis is impossible to test experimentally, but in a paper published in the International Journal of Astronomy and Astrophysics, Osmanov, who is also affiliated with the E. Kharadze Georgian National Astrophysical Observatory, calls this the "reverse panspermia problem" and calculated that "in 5 billion years dust grains can travel in the interstellar medium at distances of the order of hundreds of parsecs."
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