In particular, the south polar region of Enceladus is almost entirely free of impact craters. ... The eruptions appear to be continuous, generating an enormous halo of fine ice dust around Enceladus, which supplies material to Saturn's E-ring.

What is special about Enceladus?

Cassini revealed the dramatic truth: Enceladus is an active moon that hides a global ocean of liquid salty water beneath its crust. What's more, jets of icy particles from that ocean, laced with a brew of water and simple organic chemicals, gush out into space continuously from this fascinating ocean world.

Why is Enceladus surface smooth?

Enceladus is perturbed in its orbit by the gravitational fields of Saturn and its neighboring moon, Tethys and Dione. The smooth plains indicate a very young surface, perhaps only a few hundred million years old. These areas were almost certainly formed by water flowing to the surface from deep inside the moon.