Voyager 2 mosaic image of Ariel,taken on January 24,1986. Ariel is one of Uranus's five major satellites with a diameter of 1200km. Much of the surface is densely pitted with craters,5-10km across,with numerous valleys & fault scarps criss-crossing the terrain. Extensive faulting has occurred as a result of expansion & stretching of Ariel's crust. The largest fault valleys,near the terminator (day-night boundary) at right,as well as a smooth region (centre),have been partly filled with deposits that are younger & less heavily cratered. Narrow,sinuous (winding) scarps & valleys have been formed later in these young deposits,either by faulting or fluid flow |