These include "sputtering" erosion - the bombardment of the surface by very fast charged particles (a process similar to sandblasting) - and impacts by meteorites.

BBC: Ice blades threaten Europa landing

The acidic water causes the erosion of the soluble rock layers beneath the surface - eventually creating cavernous spaces.

BBC: Who, What, Why: How are sinkholes formed?

Areas that in 2005 had looked like flows of material on the surface appeared on this occasion to have undergone some erosion.

BBC: Stardust probe finds 'subdued' comet crater