"The S3-3 satellite is a polar-orbiting satellite which measured dc and ac electric fields, dc magnetic fields, thermal plasma densities, and the energy and pitch angle distributions of electrons and ions in the altitude region from 1000 to 8000 km. The satellite was launched during July, 1976 into an elliptical polar orbit with an initial inclination of 97.5 deg, an apogee of 8040 km, a perigee of 240 km and an orbital period of approximately three hours. The instruments on board the satellite include two electrostatic analyzers measuring electrons from 0.17 to 8.4 keV and ions with energy per charge from 0.09 to 3.9 keV/q, in eight logarithmic channels. In addition instruments measured electrons from 0.012 to 1.6 MeV and protons from 0.08 to 1.5 MeV. An experiment of the Air Force Geophysical Laboratory consisted of a spherical Langmuir probe. Other instruments on board the satellite include a mass spectrometer, and devices for measuring vector dc and ac electric fields, dc plasma density, and temperature, and density fluctuations." . See also .
- Data from the MES instrument provided by O'Brien to ViRBO: http://virbo.org/ftp/users/obrien/s33/
- Data file reader: http://virbo.org/svn/virbo/s33