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Thirty Four Orbits Later Galileo Checks Out By Jove
After orbiting Jupiter 34 times and surviving four times the amount of radiation it was design to withstand, the resilient Galileo spacecraft is finally at the very end of its 14-year mission. To avoid even the most remote possibility of colliding with a pristine moon in the jovian system, the out-of-fuel spacecraft will dive into Jupiter on Sunday, Sept. 21, 2003.
Since its launch in 1989, the sturdy spacecraft traveled more than 4.6 billion kilometers (almost 2.8 billion miles), about the equivalent of seven times the distance between Earth and Jupiter. Despite communication problems and a temperamental tape recorder, Galileo returned 30 gigabytes of data, including 14,000 pictures.
This wealth of information drastically expanded our understanding of the solar system's biggest planet and its moons. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy.
As the first spacecraft in long-term residence in jovian orbit, Galileo also successfully studied the global structure and dynamics of Jupiter's magnetic field. Galileo also determined that Jupiter's ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet's four small inner moons. Data also showed that Jupiter's outermost ring is actually made up of two rings, one embedded within another.
Io has extensive volcanic activity, which is continually modifying the surface. The heat and the frequency of eruption can be 100 times more than that of Earth, something reminiscent of Earth's early days. The similarities make Io an ideal laboratory for the study of what Earth was like more than 3 billion years ago.
The moon Europa, Galileo unveiled, could be hiding a salty ocean up to 100 kilometers (62 miles) deep underneath its frozen surface. Images also reveal ice "rafts" the size of cities that have broken and drifted apart to create a scalloped and broken surface. There are also indications of volcanic ice flows, with liquid water flowing across the surface. These discoveries are particularly intriguing since liquid water is a key ingredient in the process that may lead to the formation of life.
The biggest discovery surrounding Ganymede was the presence of a magnetic field, the first moon of any planet known to have one. Images of this moon featured a faulted and fractured surface that demonstrated high tectonic activity. Like Europa and Io, Ganymede has a metallic core. Galileo magnetic data also provided evidence that Ganymede might have a liquid-saltwater layer as well.
Galileo determined that, while Callisto doesn't have a metallic core, its surface shows evidence of extensive erosion. Data collected raise the question of whether Callisto's surface may also hide an ocean.
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Galileo To Taste Jupiter Before Taking Final Plunge
Pasadena - Sep 18, 2003
In the end, the Galileo spacecraft will get a taste of Jupiter before taking a final plunge into the planet's crushing atmosphere, ending the mission on Sunday, Sept. 21. The team expects the spacecraft to transmit a few hours of science data in real time leading up to impact.