Europa, Jupiter's second Galilean satellite, is among the most interesting targets for planetary exploration in our solar system.
NASA's Galileo mission discovered strong evidence for the presence of a deep water ocean beneath its icy surface (right).
If material from Europa's ocean is making its way to the surface (through convection or some other geologic process), a robotic lander could provide a window into the ocean's habitability by collecting and studying samples.
NASA scientists think that reconnaissance from orbit or multiple flybys would be the best way to prepare before a lander mission can be attempted.
