OSO - Credit: NASA. 14,862 bytes. 362 x 260 pixels.

The Orbiting Solar Observatories, developed for NASA's Goddard Space Flight Center, were designed primarily as stabilised platforms for solar-oriented scientific instruments. The OSOs permitted the first extended study of the sun (from above the earth's filtering atmosphere) with accurate positioning. Experiments on the satellites studied the sun, flares and other solar activities, X-ray, gamma and ultraviolet radiation and radiation from extra-solar sources. The two section space observatory was stabilised because the lower section, the "wheel," spinned as a gyroscope at a near constant 30 revolutions per minute. The upper fan-shaped section, the "sail," was joined to the wheel by a connecting shaft and remained pointed toward the sun during the OSO daytime. Experiments in the wheel scanned the sun every 2 seconds and those in the sail pointed continuously at the sun. The OSO was placed in orbit 565 km above earth by a Delta booster and circled the earth every 96 minutes Each spacecraft weighed from 200 to 280 kg (including eexperiments) and carried up to 9 experiments Each of the 3 successful OSO�s exceeded their five month design specification. OSO 1, launched March 7, 1962, was. in operation nearly 18 months; OSO 2, launched February 3, 1965, nearly 9 months; OSO 3, launched March 8, 1967, and OSO 4, launched October 18, 1967, continued to send back scientific data through year-end 1968. Prime Contractor was Ball Brothers Research Corporation. 280

Orbiting Solar Observatory; solar flare observations. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory; returned solar X-ray, UV, gamma ray data. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Extreme UV solar observations. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory; solar radiation data. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory; solar physics experiments. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

Orbiting Solar Observatory. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).

• 126 - Bramscher, Robert G, Spaceflight, "A Survey of Launch Vehicle Failures", 1980, Volume 22, page 351.
• 405 - Aerospace Yearbook, 1966, .