The cracks may be curvilinear as well, as seen in this view of the Theros and Thrace region near the southern pole of Europa. The picture below shows closely-spaced parallel cracks, with different orientations, in two blocks separated by a high ridge, furrowed in its center. Individual rafts are grooved, but the grooves vary from raft to raft indicating that they floated as breakoffs from grooved terrain or alternatively were reoriented by pushing around from a disrupted terrain. This supposition has fueled intense interest in getting even closer approaches to Europa, which planners scheduled in the continuing Galileo observations. Officials are considering a new mission in the early 21st century, specifically to search for more signs of life.
More recent observations shed further light on the variety of terrains on Europa.
Note the single flat lineated plate at the top. Although impact craters, especially larger ones, are quite uncommon on Europa, a few exist, such as this one, not yet destroyed by ice movements, known as Tyre Crater. This sparsity indicates that Europa is an active planet, with continual or periodic replating of its surface in a process affected by the presumed liquid ocean beneath its ice cover.