The Environmental Research Satellite 17 carried a set of five radiation detectors designed to measure charged particles, X rays, gamma rays, and cosmic rays in the near-earth environment. The satellite was spin stabilized with a spin rate of approximately 6 rpm. A 16-channel PAM/FM/PM telemeter using a subcommutator and IRIG (Inter-Range Instrumentation Group) FM channel 5 was employed. Each channel was sampled for 4.5 s every 72 s. Data coverage was obtained at about an 86% level for the initial 4 weeks of operation and at about a 26% level thereafter until November 3, 1965, when the transmitter ceased. Approximately 1500 h of data were obtained.