The spacecraft systems performed normally except for the malfunction of the solar cell power dump device shortly after launch, which caused the solar cells to deliver a lower power level to the experiments and reduced the time during which the onboard tape recorder could be run.

[3] This experiment was designed to conduct detailed measurements of trapped and precipitating proton and electron energy fluxes, separately, over the range 50 eV to 50 keV.

The energy spectra of these particles were studied separately as a function of pitch angle, latitude, local time, altitude, and magnetic activity.

[4] This experiment was designed to conduct an investigation of the spatial and temporal distributions and energy spectra of low-energy alpha particles, protons, and electrons.

[5] Two four-grid spherical retarding potential analyzers were used to measure thermal and nonthermal ions and electrons in the energy range 0 to 2 keV.

The MCR and ECR 1 observed and telemetered (on a 0.8-watts, 400-MHz channel) analog, broadband data in real time, when the spacecraft was in telemetry range of a ground station.

Failure of the spacecraft power regulator early in the mission limited operation to some extent, but nominal data were obtained until 29 May 1970.