The penetrator (yep, that's its name. Moving on...) would launch from a satellite orbiting Europa and lodge itself a few meters into the moon's ice. Despite its militaristic appearance, the penetrator is really a research vessel designed to carry seismometers and other scientific equipment. These sensors could relay information back to the satellite and, from there, back to Earth. Multiple penetrators could be fired from a single satellite, covering Europa in ballistic impact wounds and scientific collection tools, which combined would paint a more complete picture of the moon.