LPSC 2007: How did Europa get so pock-marked?
Here's a thought - Jupiter's volcanic moon Io is responsible for most of the rocky stuff on another of Jupiter's moons, Europa. So says Kevin Zahnle of NASA's Ames research center.
Objects crashing into Io cause chunks of basalt to fly off the surface. "Piano-sized stuff," Zahnle told me. Not just piano sized, but fridge or car sized as well.
These secondary ejecta land on Europa bringing what Zahnle said, to ripples of chuckles in the audience, is an important source of vitamins and minerals to Europa. And by mass, these Io remnants are more important for Europa's rockyness than micrometeoroids.
Zahnle insisted that this was just a basic piece of science, "it might not be right," he added. The best way to test will be to check for the basalt signature on Io, he said.