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
Extraterrestrial skies (Jupiter, Saturn, Uranus and Neptune) would appear slightly brighter during opposition, but slightly dimmer during conjunction. This effect is most noticeable for Jupiter, and results from Mars' larger orbit compared with that of Earth causing larger variations of interplanetary distance. From Phobos, Mars appears 6,400 times larger and 2,500 times brighter than the full Moon as seen from Earth, and appears as a sphere of angular diameter roughly 42°—taking up a quarter of the width of a celestial hemisphere. From Deimos, Mars appears 1,000 times larger and 400 times brighter than the full Moon as seen from Earth, and appears