— Ch. 1 · Mission Genesis And Design —
International Cometary Explorer.
~4 min read · Ch. 1 of 6
On the 12th of August 1978, the International Sun-Earth Explorer-3 satellite lifted off into a heliocentric orbit. This launch marked the beginning of a joint effort between NASA and ESRO/ESA to study solar wind interactions with Earth's magnetic field. The spacecraft was one of three built for the program, alongside ISEE-1 and ISEE-2. It carried no cameras or imaging systems. Instead, its instruments measured energetic particles, waves, plasmas, and fields. Four long antennas protruded equidistant around the cylindrical body, spanning four meters in total length. The dry mass weighed 405 kilograms while generating nominal power of 173 watts from its solar panels. Its transmitter output power reached five watts during transmission cycles.
Lagrange Point Innovation
The probe entered an orbit at the Sun-Earth Lagrange point on the 20th of November 1978. This location sat 235 Earth radii above the surface, proving that suspension between gravitational fields was possible. ISEE-3 became the first artificial object placed in such a halo orbit. It rotated at 19.76 rpm about an axis perpendicular to the ecliptic plane. This rotation kept it oriented for experiments, generated solar power, and maintained communication links with Earth. The mission objectives included investigating solar-terrestrial relationships at the outermost boundaries of Earth's magnetosphere. Scientists examined the structure of the solar wind near Earth and the shock wave forming the interface. They studied motions within plasma sheets and continued cosmic ray investigations in the interplanetary region near one astronomical unit.