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The International Cometary Explorer (ICE) spacecraft (designed and launched as the International Sun-Earth Explorer-3 (ISEE-3) satellite), was launched August 12, 1978, into a heliocentric orbit. It was one of three spacecraft, along with the mother/daughter pair of ISEE-1 and ISEE-2, built for the International Sun-Earth Explorer (ISEE) program, a joint effort by NASA and ESRO/ESA to study the interaction between the Earth's magnetic field and the solar wind. ISEE-3 was the first spacecraft to be placed in a halo orbit at the Earth-Sun Lagrangian point. Renamed ICE, it became the first spacecraft to visit a comet, passing through the plasma tail of Comet Giacobini-Zinner within about of the nucleus on September 11, 1985. NASA suspended routine contact with ISEE-3 in 1997, and made brief status checks in 1999 and 2008. On May 29, 2014, two-way communication with the spacecraft was reestablished by the ISEE-3 Reboot Project, an unofficial group with support from the Skycorp company. On July 2, 2014, they fired the thrusters for the first time since 1987. However, later firings of the thrusters failed, apparently due to a lack of nitrogen pressurant in the fuel tanks. The project team initiated an alternative plan to use the spacecraft to "collect scientific data and send it back to Earth," but on September 16, contact with the probe was lost. ==Original mission: International Sun/Earth Explorer 3 (ISEE-3)== ISEE-3 carries no cameras; instead, its instruments measure energetic particles, waves, plasmas, and fields. ISEE-3 originally operated in a halo orbit about the Sun-Earth Lagrangian point, 235 Earth radii above the surface (about 1.5 million km, or 924,000 miles). It was the first artificial object placed at a so-called "libration point", entering orbit there on November 20, 1978,〔 proving that such a suspension between gravitational fields was possible. It rotates at 19.76 rpm about an axis perpendicular to the ecliptic, to keep it oriented for its experiments, to generate solar power and to communicate with Earth. The purposes of the mission were: * to investigate solar-terrestrial relationships at the outermost boundaries of the Earth's magnetosphere; * to examine in detail the structure of the solar wind near the Earth and the shock wave that forms the interface between the solar wind and Earth's magnetosphere; * to investigate motions of and mechanisms operating in the plasma sheets; and, * to continue the investigation of cosmic rays and solar flare emissions in the interplanetary region near 1 AU. 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「International Cometary Explorer」の詳細全文を読む スポンサード リンク
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