International Sun-Earth Explorer

International Sun–Earth Explorer

(ISEE) A joint project of NASA and ESA for studying the structure and interactions within the Earth's magnetosphere and the solar phenomena producing such effects. The two satellites ISEE–1 and ISEE–2 were launched in tandem, in Oct. 1977, into a highly eccentric Earth orbit at a controllable distance apart. ISEE–3 was launched in Aug. 1978 into an orbit around the Sun–Earth Lagrangian point L1, a point lying outside the magnetosphere, where it measured the solar wind, solar flares, and sunspots, unperturbed by the Earth's influence. It was thus a reference point for simultaneous observations made by ISEE–1 and ISEE–2. In 1982/83 the trajectory of ISEE–3 was altered so that it would intercept the comet Giacobini-Zinner. The craft was renamed the International Cometary Explorer (ICE). It was the first spacecraft to rendezvous with two comets, flying through the plasma tail of Giacobini-Zinner in Sept. 1985, where it made particle, field and wave measurements, and passing between the Sun and Halley's comet in March 1986, at a distance from Halley's nucleus of 28 million km. By 1990, ICE had taken up a 355-day orbit around the Sun. In 1991, its mission was extended once more in order to study coronal mass ejections and cosmic rays. It was also occasionally linked up with ESA's Ulysses probe on certain science projects. NASA shut down the spacecraft in May 1997. It will return to the vicinity of the Earth in 2014. NASA has already agreed that, if the craft can be recovered successfully, it is to be donated to the Smithsonian Institute.
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