The International Cometary Explorer mission to comets Giacobini-Zinner and Halley: an update.

On September 11, 1985 the in situ exploration of comets will begin with the pass of the International Cometary Explorer (ICE) spacecraft through the plasma tail of Comet Giacobini-Zinner (G/Z). The primary scientific goal of the ICE mission is to study the interaction of the solar wind with comets by penetrating the downstream plasma environment. The ICE studies of Comet Giacobini-Zinner are complementary to the direct exploration of Halley's Comet in March 1986, and the ICE encounter provides a first test of spacecraft systems in a cometary environment. ICE will also serve as an upstream monitor of solar-wind conditions for Comet Halley during two time periods. The near-radial alignments occur on October 31, 1985 and March 28, 1986 when ICE will be 0.93 and 0.21 AU upstream, respectively.