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The objectives of this satellite 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, X-ray, and gamma radiation. The OSO 4 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 seven experiments. Attitude adjustment was performed by gas jets and a magnetic torquing coil. 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 140 ground-based commands. The spacecraft performed normally until the second tape recorder failed in May 1968. The spacecraft, which was put in standby condition in November 1969, would be turned on only for recording special events in real time. Such an event occurred on March 7, 1970, when OSO 4 recorded data during the solar eclipse. For more information, see A. W. L. Ball, Spaceflight, v. 12, p. 244, 1970.

Alternate Names

  • 03000
  • OSO-D
  • OSO4

Facts in Brief

Launch Date: 1967-10-18
Launch Vehicle: Delta
Launch Site: Cape Canaveral, United States
Mass: 605 kg

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Space Physics
  • Solar Physics
  • Astronomy

Additional Information

Questions and comments about this spacecraft can be directed to: Dr. H. Kent Hills



NameRoleOriginal AffiliationE-mail
Mr. Laurence T. HogarthProject ManagerNASA Goddard Space Flight Center
Dr. Henry J. SmithProgram ScientistNASA Headquarters
Dr. William E. BehringProject ScientistNASA Goddard Space Flight
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