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STS-34 / IUS | launch_site = Kennedy Space Center LC-39B | launch_contractor = | entered_service = December 8, 1995 | disposal_type = Deorbited | decay_date = UTC | orbit_epoch = | orbit_reference = Geocentric | orbit_periapsis = | orbit_apoapsis = | orbit_inclination = | orbit_period = | apsis = zene |interplanetary = }} ''Galileo'' was an unmanned spacecraft that studied the planet Jupiter and its moons, as well as several other Solar System bodies. Named after the astronomer Galileo Galilei, it consisted of an orbiter and entry probe. It was launched on October 18, 1989, carried by Space Shuttle ''Atlantis'', on the STS-34 mission. ''Galileo'' arrived at Jupiter on December 7, 1995, after gravitational assist flybys of Venus and Earth, and became the first spacecraft to orbit Jupiter. It launched the first probe into Jupiter, directly measuring its atmosphere.〔(【引用サイトリンク】title=Galileo End of Mission Press Kit )〕 Despite suffering major antenna problems, ''Galileo'' achieved the first asteroid flyby, of 951 Gaspra, and discovered the first asteroid moon, Dactyl, around 243 Ida. In 1994, ''Galileo'' observed Comet Shoemaker–Levy 9's collision with Jupiter.〔 The spacecraft was an international effort by the United States of America and the Federal Republic of Germany.〔 Jupiter's atmospheric composition and ammonia clouds were recorded, the clouds possibly created by outflows from the lower depths of the atmosphere. Io's volcanism and plasma interactions with Jupiter's atmosphere were also recorded. The data ''Galileo'' collected supported the theory of a liquid ocean under the icy surface of Europa, and there were indications of similar liquid-saltwater layers under the surfaces of Ganymede and Callisto. Ganymede was shown to possess a magnetic field and the spacecraft found new evidence for exospheres around Europa, Ganymede, and Callisto.〔 ''Galileo'' also discovered that Jupiter's faint ring system consists of dust from impacts on the four small inner moons. The extent and structure of Jupiter's magnetosphere was also mapped.〔 On September 21, 2003, after 14 years in space and 8 years in the Jovian system, ''Galileo'' mission was terminated by sending it into Jupiter's atmosphere at a speed of over per second, eliminating the possibility of contaminating local moons with terrestrial bacteria. ==Background== In the early 1970s the first flybys of Jupiter were achieved by Pioneer 10 and Pioneer 11, and before the decade was out it was also visited by the more advanced Voyager 1 and Voyager 2 spacecraft. Jupiter was rated as the number one priority in the Planetary Science Decadal Survey published in the summer of 1968. Jupiter is the largest planet in the solar system and its largest moon, Ganymede, is bigger than Mercury. (see also Moons of Jupiter) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Galileo (spacecraft)」の詳細全文を読む スポンサード リンク
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