University of Colorado at Boulder University of Colorado CU Home Search A to Z Index Map

Quick Facts: Orbiting Solar Observatory-5 (OSO-5)

Mission Introduction

OSO 5 Spacecraft

OSO 5 was launched on 22 January 1969, and lasted until July 1975. It was the 5th satellite put into orbit as part of the Orbiting Solar Observatory program. (Courtesy NASA/GSFC)

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, X-ray and gamma radiation. The OSO-5 platform consisted of a sail section that pointed two experiments continually toward the sun and a wheel section that spun about an axis perpendicular to the pointing direction of the sail and carried six experiments. Attitude adjustments were performed by gas jets and a magnetic torquing coil. Pointing control permitted the pointed experiments to scan the region of the solar disk in a 40- by 40-arc-min raster pattern. In addition, the pointed section could be commanded to select and scan a 7.5- by 7-arc-min region near the solar disk. Data were simultaneously recorded on tape and transmitted by PCM/PM telemetry. A command system provided for 155 ground-based commands.

LASP Roles

LASP provided:

  • Solar Extreme Ultraviolet Monitor
  • Solar Extreme Ultraviolet Monitor Principal Investigator, William Rense

LASP Instrument

The Solar Extreme Ultraviolet Monitor was designed to:

  • Observe temporal variations of solar UV intensity in three broad bands between 28 nm and 103 nm (28 to 37 nm, 46.5 to 63 nm, and 76 to 103 nm)
  • Observe variations in intensity in these bands during solar flares
  • Make estimates for the three UV bands of active and quiet region contributions and limb brightening as a result of measurements made during solar eclipses
  • Make an approximate determination of the differences in temperature and constituent number densities of the earth’s upper atmosphere between sunrise and sunset

The instrumentation, located in the wheel section of the OSO 5 spacecraft, consisted of a single Rowland-mounted, concave, grazing-incidence, grating spectrophotometer, which dispersed the radiation into the three bands, and three Bendix resistance-strip-type photomultipliers, which detected the radiation in each band. Counts from each band were obtained during every revolution of the satellite (about 2s) during the daylight portion of the orbit, including sunrise and sunset. The count range was from 100 to 20,000, but variations of more than 5% caused by pitch changes or interference were sometimes present. Inflight calibration, namely a check on the grating reflectivity and photomultiplier response, was made at regular intervals for the first few weeks of operation but was discontinued because of a malfunction of the calibration lamp. A background reading was also taken periodically while the instrument was looking away from the sun. Because of the calibration lamp malfunction, the instrument was deactivated by ground command in May 1969.

Quick Facts

Launch date: January 22, 1969
Launch location: Kennedy Space Center, Cape Canaveral, Florida
Launch vehicle: Delta
Mission target: Earth orbit
Mission duration: 6 1/2 years
Other organizations involved:

  • NASA’s Goddard Space Flight Center
  • Ball Aerospace