Jupiter's satellite Europa

Jupiter

. Dark streaks mark Europa's smooth surface, forming a spidery, veined network in this Voyager 2 image taken on 9 July 1979. In contrast to Jupiter's satellite Callisto (Fig. 2.23), Europa has very few impact craters; the absence of craters suggests that the ice crust is relatively young. Internal stresses apparently fractured its icy mantle, producing intersecting cracks that extend for millions of meters, but reach depths of less than 100 meters. The fractures may have been filled by liquid water gushing out from a global ocean in the satellite's interior, warmed by tidal heating. (Courtesy of NASA and JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University