Enceladus

Enceladus is one of Saturn's moons, considered an inner moon, one of Saturn's closer major moons. It is apparently covered with ice and shows water plumes, suggesting subsurface water, which conceivably could harbor life. The plumes supply the material for Saturn's E ring. A proposed mission, the Enceladus Life Finder (ELF), is intended to look further for life signs. The plumes are emitted from cracks along the center of four visible ridges in a region of the surface, that are known as the Enceladus tiger stripes or Enceladean sulci.

Precise measurements of Enceladus's physical libration (i.e., forced libration) over time have supported models with Enceladus's core not solidly connected to its surface, i.e., that an ocean surrounds the whole core. Enceladus's libration is large enough to eliminate many alternate explanations.