The International Cometary Explorer satellite – originally launched as International Sun-Earth Explorer 3 in 1978 – reaches the culmination of a series of complex orbital changes: a flyby of Comet Giacobini-Zinner, within 5,000 miles of the nucleus, primarily to sample and study the comet’s plasma tail and the interaction between that and the solar wind. ISEE-3 was not equipped with cameras at launch, so no imagery of the comet is obtained. The success of this flyby emboldens mission planners who hope to send it onward to study Halley’s Comet early in 1986, as part of a backup plan to use existing NASA spacecraft to study Halley in lieu of a specialized vehicle that would’ve been launched by space shuttle in 1986 (cancelled in the wake of the Challenger disaster).
