Transmitting antennas consisted of two fiberglass slot antennas in the body of the satellite itself and four flexible whips forming a turnstile antenna. The rotation of the satellite about its long axis kept the flexible whips extended.
The external skin of the instrument section was painted in alternate strips of white and dark green to provide passive temperature control of the satellite. The proportions of the light and dark strips were determined by studies of shadow-sun-light intervals based on firing time, trajectory, orbit, and inclination.
Electrical power was provided by nickel cadmium chemical batteries that made up approximately 40 percent of the payload weight. These provided power that operated the high power transmitter for 31 days and the low power transmitter for 105 days.
Because of the limited space available and the requirements for low weight, the Explorer I instrumentation was designed and built with simplicity and high reliability in mind. It was completely successful.
