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The Journey to Jupiter
Extended Tours - GEM and the Millennium Mission

Galileo's prime mission ended on December 7, 1997. With more to learn, and the spacecraft in good health, NASA approved a two-year study called "GEM" -- the Galileo Europa Mission. For fourteen more orbits, the spacecraft focused on ice, water, and fire: the icy moon Europa, which might have an ocean; Jupiter's majestic thunderstorms; and the fiery volcanoes of Io.

The Galileo Europa Mission Encounter Timeline.
The Galileo Europa Mission Encounter Timeline.

The spacecraft came so close to Europa that if there were something there the size of a school bus, Galileo would have detected it. The additional observations of Europa supported the theory that an ocean of water currently exists below the surface. NASA began considering plans for future missions to orbit Europa, and perhaps to send a lander.

Approaching Io --- Jupiter's innermost moon --- meant surviving Jupiter's intense radiation, so these encounters were saved until last. When radiation upset the spcecraft's computer, engineers worked all night to get them back on line. But Galileo came through again, and even discovered a lava fountain erupting on Io.

The Galileo Europa Mission Orbital Map.
The Galileo Europa Mission Orbital Map.

These successful flybys led to another exciting mission --- the Galileo Millennium Mission, extending into 2001. The data are collected on Io and Europa, and studies made of the effects of radiation on a spacecraft close in to Jupiter. The Cassini spacecraft, on its way to Saturn, swings by Jupiter in late 2000 and for a few weeks, both spacecraft observe the giant of our Solar System.

The Future: Jupiter Icy Moons Orbiter Next

Next: The Spacecraft Next

Spacecraft
Mission Operations
Ice crust of Europa
Ice crust of Europa
Thunderheads on Jupiter
Thunderheads on Jupiter
Active Volcanic Plumes on Io
Active Volcanic Plumes on Io