ISEE-1/ISEE-2

The ISEE program (International Sun Earth Explorer) was a joint mission between NASA and ESA, part of the IMS (International Magnetospheric Study). It was based on three spacecrafts and aiming at a better understanding of the Solar Wind-Earth Magnetosphere interaction. ISEE-1 built by NASA and ISEE-2, built by ESA, were launched simultaneously on October 22, 1977 on the same Earth orbit with a close and controlled separation distance between the two spacecrafts, ranging from about 50 and 5000 km.
This allowed, for the first time, to discriminate between space and time ambiguities induced by single spacecraft observations of thin and moving magnetospheric boundaries such as the bow shock, the magnetopause and the tail current sheet. The ISEE-3 spacecraft, built by NASA and launched on August 12, 1978 was placed at the L1 Lagrange Point, where it provided the characteristics of the Solar Wind, 235 Earth Radii upstream of the Earth, about one hour before it impacts the Earth Magnetosphere studied by the ISEE-1-2 pair. This mission was the first one to provide an estimation of the magnetopause width.

Access to mission data

Access to mission documents