The Orbiting Geophysical Observatories and the supporting ground checkout equipment, data acquisition and tracking stations and data processing equipment are designed to conduct large numbers of diverse experiments in space. Measurements will be made within the earth's atmosphere, ionosphere, exosphere, magnetosphere, and in cislunar space to obtain a better understanding of earth-sun relationships and of the earth as a planet. Configured to meet scientific requirements, the observatories include six booms to support detectors away from disturbances generated in the main body. Five degrees of freedom allow the orientation of experiments relative to three references — the earth, the sun, and the orbital plane. Power, thermal control, and data handling subsystems provide for the proper operation of the experiments and telemetry of the data. Ground stations receive these data, which are then processed into a form suitable for use by the experimenters. The systems have been designed to make available a standard spacecraft and support equipment which can be used repeatedly to carry large numbers of easily integrated experiments in a wide variety of orbits.