Europa's icy shell: A bridge between its surface and ocean

Europa,a Moon‐sized, ice‐covered satellite of Jupiter, is second only to Mars in its astrobiological potential. Beneath the icy surface, an ocean up to 150 km deep is thought to exist, providing a potential habitat for life, and a tempting target for future space missions. The Galileo mission to the Jovian system recently ended, but there are already long‐range plans to send much more capable spacecraft, such as the proposed Jupiter Icy Moons Orbiter (JIMO), to take a closer look at Europa and her siblings, Ganymede and Callisto, some time in the next two decades. Europa's outer icy shell is the only interface between this putative ocean and the surface, but many aspects of this shell are presently poorly understood; in particular, its composition, thickness, deformational history, and mechanical properties.