ISEE (International Sun-Earth Explorer)

A series of three ISEE (International Sun-Earth Explorer) spacecraft was built and operated as a fleet by NASA and ESA (European Space Agency) to study the influence of the Sun on Earth's space environment and magnetosphere. Specific goals of the mission were to investigate solar-terrestrial relationships at the outermost boundaries of Earth's magnetosphere, the structure of the solar wind near Earth and the shock wave that forms the interface between the solar wind and Earth's magnetosphere, motions of and mechanisms operating in the plasma sheets, and cosmic rays and solar flare emissions in the near interplanetary region. The three spacecraft carried a number of complementary instruments for making measurements of plasmas, energetic particles, waves, and fields and extended the investigations of previous IMP missions.


ISEE-3 was initially placed into an elliptical halo orbit about the L1 Lagrangian point – the first spacecraft to use such an orbit – 235 Earth-radii out on the sunward side of Earth, where it continuously monitored changes in the near-Earth interplanetary medium. In conjunction with the ISEE-1 and ISEE-2 mother and daughter spacecraft, which had eccentric geocentric orbits, it explored the coupling and energy transfer processes between the incoming solar wind and Earth's magnetosphere. ISEE 3 also provided a near-Earth baseline for making cosmic-ray and other planetary measurements for comparison with corresponding measurements from deep-space probes. In 1982, it carried out a series of maneuvers based on the revolutionary new technique of chaotic control which resulted in it being ejected out of the Earth-Moon system and into a heliocentric orbit ahead of Earth, on a trajectory intercepting that of comet Giacobini-Zinner. At this time, ISEE-3 was renamed ICE (International Cometary Explorer).


All the ISEE spacecraft were launch by Delta 2914 rockets from Cape Canaveral.


spacecraft launch date orbit mass (kg)
ISEE-1 Oct 22, 1977 436 × 137,806 km × 12.7° 340
ISEE-2 " 406 × 137,765 km × 13.5° 166
ISEE-3 Aug 12, 1978 181 × 1,089,200 km × 1.0° 479