This image taken by NASA's Galileo spacecraft in the late 1990s shows Europa’s ice shell, marked by fractures and impact craters, and it evokes a sense of mystery about what lies within it and beneath that shell. The color variations on the surface show that there’s communication between the surface and subsurface, the nature of which is a subject of intense study. This paper helps us to understand the effects of constant surface bombardment on materials that may be available for study at the surface. (Image: JPL-Caltech / SETI Institute via NASA)
