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 was the first spacecraft to orbit the Sun at L1, a location in space where an object remains directly between Earth and Sun throughout its orbit. Coordinated with the two Earth-orbiting satellites in the International Sun-Earth Explorer (ISEE) program, ISEE-3 enabled scientists to measure solar and geomagnetic phenomena from different points in time and space. It was the first spacecraft to monitor the solar wind approaching Earth, and continued the investigation of cosmic rays and solar flare emissions in the interplanetary region near Earth's orbit.