Goals: International Sun-Earth Explorer-3 (ISEE-3) was to investigate the solar wind and its interaction with Earth's magnetic field, among other phenomena in interplanetary space. It was later renamed International Cometary Explorer (ICE) and used to study two comets during an extended mission.

Accomplishments: ISEE-3 conducted the first deep survey of Earth's magnetic tail. Then, after a series of complex flybys of the Moon, the spacecraft was renamed the International Cometary Explorer (ICE) and became the first spacecraft to fly past a comet (Giacobini-Zinner). Its observations supported the theory that comets are "dirty snowballs." The following year, it joined international exploration of Comet Halley by providing data on the solar wind approaching the comet.