Exploration of Jupiter reach Europa after a 6.5 year cruise. The spacecraft would fly by the moon 32 times to minimize radiation damage. Because of the possibility of subsurface liquid oceans on Jupiter's moons Europa, Ganymede and Callisto, there has been great interest in studying the icy moons in detail. Funding difficulties have delayed progress. The "Europa Orbiter" was a planned NASA mission to Europa, which was canceled in 2002. Its main objectives included determining the presence or absence of a subsurface ocean and identifying candidate sites for future lander missions. NASA's "JIMO" ("Jupiter Icy Moons Orbiter"), which was canceled in 2005, and
Climate of Mars 5–10 times higher velocities than Earth grains do. A large doughnut shaped cloud appears in North polar region of Mars around the same time every Martian year and of about the same size. It forms in the morning and dissipates by the Martian afternoon. The outer diameter of the cloud is roughly , and the inner hole or eye is across. The cloud is thought to be composed of water-ice, so it is white in color, unlike the more common dust storms. It looks like a cyclonic storm, similar to a hurricane, but it does not rotate. The cloud appears