 A high-gain directional dish antenna was attached to the bottom of the base.Spacecraft experiments and other equipment were mounted on the base and tower.Instruments aboard the spacecraft included a Lyman-alpha telescope, a rubidium-vapor magnetometer, electrostatic analyzers, medium-energy range particle detectors, two triple coincidence telescopes, a cosmic-ray integrating ionization chamber, cosmic dust detectors, and solar X-ray scintillation counters.