ISIS 1 (International Satellite for Ionosphere Studies) was an ionospheric observatory instrumented with sweep- and fixed-frequency ionosondes, a VLF receiver, energetic and soft particle detectors, an ion mass spectrometer, an electrostatic probe, an electrostatic analyzer, a beacon transmitter, and a cosmic noise experiment.

Mission type: Earth Science · Orbit: Elliptical Orbit

Rocket: Thor Delta E1 · Provider: United States Air Force