The study examined where Jupiter’s radiation hits hardest. In those areas, the surface is too continually battered by radiation for some amino acids—the building blocks of proteins—to persist. But about 4 to 8 inches down, those amino acids are a bit more protected. It could work like this: amino acids from the interior ocean get ejected into space, change due to the radiation, fall back to the surface, and become covered by more ice deposits on a timescale that allows some amino acids to survive. In turn, a future lander would just have to take a core sample deep enough to find the amino acids and confirm that Europa is ripe for life. In areas outside the harshest parts of the radiation, the amino acids might be literally right under the surface.