ISEE-3

The third in a series of three International Sun-Earth Explorer satellites, a joint effort between NASA and the European Space Agency, is launched aboard a Delta rocket from Cape Canaveral. Unlike the other ISEE satellites, ISEE-3 is intended to take up a “halo” orbit at the L1 LaGrangian point between the sun and Earth, the first man-made space vehicle to do so. There it will study the interaction between the solar wind and Earth’s own magnetosphere. Once its mission is completed in the early 1980s, it will be redirected and renamed to become the first Earth spacecraft to study a comet at close range.