The objectives of the OSO satellite series were to perform solar physics experiments above the atmosphere during a complete solar cycle and to map the entire celestial sphere for direction and intensity of UV light and X-ray and gamma radiation. The OSO 2 platform consisted of a sail section, which pointed two experiments continuously toward the sun, and a wheel section, which spun about an axis perpendicular to the pointing direction of the sail and carried six experiments. Attitude adjustment was performed by gas jets. A pointing control system permitted the pointed experiments to scan the region of the sun in a 40- by 40-arc-min raster pattern. Data were simultaneously recorded on tape and transmitted by PCM/PM telemetry. A command system provided for 70 ground-based commands. The spacecraft performed normally until the pitch gas supply neared exhaustion on November 6, 1965. The spacecraft was then placed in a stowed condition. The transmitter was commanded on intermittently until March 3, 1966, and then on a weekly schedule until June 1, 1966, when it ceased operation. For more information, see A. W. L. Ball, Spaceflight, v. 12, p. 244, 1970.