In a simulation, Worth Sigurdsson and House (2013) (WSH) retrodict that Europa, Callisto, Titan, and Enceladus have received 1,900, 370, 510 and 340 metric tons of material from Earth, with 3.4 billion metric tons from Earth ejected from the solar system entirely. Enceladus may be less interesting if it really did only form in the cretaceous, but the others have all been there since the start of the solar system. WSH state explicitly that they didn't try to estimate the viability of life surviving the journey, but it cannot be repeated enough that we now have evidence that living things - metazoans, in fact - can survive uncontrolled re-entry with minimal protection, as some worms that were on board the Columbia were found alive on the ground weeks later. We're now able to start putting bounds at least on local panspermia (within our own solar system), though it would be interesting to estimate the chances for gravitational capture by surrounding stars. This is exciting not only to flesh out the realism of panspermia as traditionally considered, but also the idea of very small, molecule- or cell-sized organic von Neumann probes passively spreading between lower-gravity bodies.
A very basic calculation using water surface area and the time it took for life to appear on Earth, shows that all other things being equal, there is a 1-in-3 chance of indigenous life on Europa. An experiment in reproducing impact conditions and local conditions on these moons, along with adding most-likely-transferred Earth fauna, seems that it would be fairly easy to do - a sort of Miller-Urey experiment for local panspermia.
R.J. Worth, Steinn Sigurdsson, and Christopher H. House. Seeding Life on the Moons of the Outer Planets via Lithopanspermia. Astrobiology, Dec 2013.
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