  Material from the surface of a planet can be ejected into space by a large
impact, and could carry primitive life forms with it. We performed n-body
simulations of such ejecta to determine where in the Solar System rock from
Earth and Mars may end up. We find that, in addition to frequent transfer of
material among the terrestrial planets, transfer of material from Earth and
Mars to the moons of Jupiter and Saturn is also possible, but rare. We expect
that such transfer is most likely during the Late Heavy Bombardment or during
the next one or two billion years. At this time, the icy moons were warmer and
likely had little or no icy shell to prevent meteorites from reaching their
liquid interiors. We also note significant rates of re-impact in the first
million years after ejection. This could re-seed life on a planet after partial
or complete sterilization by a large impact, which would aid the survival of
early life during the Late Heavy Bombardment.
