Relay 1 was principally a communications satellite. Included in its payload were radiation experiments designed to map the earth's radiation belts. The spin-stabilized spacecraft had an initial spin rate of 167.3 rpm and an initial spin axis orientation with a declination of -68.3 deg and a right ascension of -56 deg. Shortly after launch, two basic problems evolved. One was the satellite's response to spurious commands, and the other was the leakage of a high-power regulator. This leakage caused the first 2 weeks of satellite operation to be useless. After this period, satellite operation returned to normal. The satellite carried one transmitter for tracking and one for telemetry. The telemetry system was PCM at 1152 bps. Each 128 words per telemetry frame (of 1 s duration) used 113 words for the particle experiment. The leakage problem caused the spacecraft to revert to a low voltage state early in 1965. Sporadic transmission occurred until February 10, 1965, after which no usable scientific data were obtained.