Orbiting Astronomical Observatory - 3 (Copernicus)
Description
This mission was the third in the OAO program and its second successful spacecraft to observe the celestial sphere from above the earth's atmosphere. A UV telescope with a spectrometer measured high-resolution spectra of stars, galaxies, and planets with the main emphasis on the determination of interstellar absorption lines. Three X-ray telescopes and a collimated proportional counter provided measurements of celestial X-ray sources and interstellar absorption between 1 and 100 A. The main experiment on board was the Princeton University UV telescope, but it also carried an X-ray astronomy experiment developed by the University College London/Mullard Space Science Laboratory. Some science highlights from the mission included:
The spacecraft was equipped with an inertial reference unit (a high-precision three-axis gyro inertial system), sun sensors, a magnetometer, and star trackers, which enabled spacecraft pointing to be determined in many different ways. A bore-sight star tracker, sensitive to sixth magnitude, controlled pitch and yaw to within 5 arc-seconds. In addition, the high-resolution telescope experiment had a fine pointing control, which could control the pitch and yaw to within 0.1 arc-seconds on bright stars. Spacecraft attitude was controlled by inertia wheels and thrusters. Redundant tracking beacons facilitated ground tracking of the spacecraft. Two UHF (400.55 MHz) transmitters provided wideband telemetry for transmitting digital data to the ground stations. Two redundant VHF (136.26 MHz) transmitters were used in a narrow-band telemetry link primarily for transmitting spacecraft housekeeping data, although they served as backups for the wideband telemetry system. Two redundant pairs of VHF command receivers were carried as part of command system capable of storing 1280 commands. Data were stored on an onboard tape recorder and in core storage. An onboard processor monitored telemetry data, issued commands, and was programmed via the command receiver uplink. The observational life of the mission was August 1972 to February 1981 (9.5 years). (NASA - National Space Science Data Center) |
Facts
Spectrum Studied: X-rays, Ultraviolet Launch Date: 1972-08-21 Termination Date: 1981-02 Orbital Location: Earth orbit (752 km) Launch Vehicle: Atlas-Centaur Launch Site: Cape Canaveral, United States Mass: 2150.0 kg Funding Agency NASA-Office of Space Science (United States) |