Orbiting Astronomical Observatory - 2 (Stargazer)
Description
This spacecraft was one of a series of automated astronomical observatories that was ground controllable in orientation and was placed in a low-earth orbit. This spacecraft carried two experiment packages, which were located centrally within the spacecraft, each viewing space from opposite ends. One experiment, the Wisconsin experiment package (WEP), consisted of four stellar photometers (1000 to 4250 A), two scanning spectrometers (1000 to 4000 A), and one nebular photometer (2000 to 3300 A). The other package, Celescope, consisted of four independent telescopic Schwarzchild cameras (1200 to 2900 A). Results of the OAO-2 mission included the discovery that the halos of comets are composed of hydrogen; UV brightness of novae increases while visible light fades; and galaxies are brighter in the UV than expected based upon visible light analysis of the stars they contain. Data obtained from this mission were used to investigate interstellar dust. Data further enabled empirical analysis of temperatures of hot stars. (Space Astronomy Laboratory – University of Wisconsin at Madison) Built in an octahedron shape, 10 ft by 7 ft, the satellite weighed 4400 pounds. The design was dictated by the stringent requirement of the experiments for pointing accuracy, pointing stability, command capability, data handling, and thermal environment, and by the constraints of the orbit for ground-station contacts. Six two-gimbal star trackers were programmed by the onboard memory to acquire and track appropriate guide stars. Error signals were generated that drove the reaction wheels to obtain stellar stabilization. Coarse momentum wheels were used for slewing the spacecraft. Memory permitted storage of 200 kilobits of experimental data. All information was relayed to the central control station in Greenbelt, MD. (NASA - National Space Science Data Center) |
Facts
Spectrum Studied: Ultraviolet, Visible Launch Date: 1968-12-07 Termination Date: 1973-01 Orbital Location: Earth orbit (772 km) Launch Vehicle: Atlas-Centaur Launch Site: Cape Canaveral, United States Mass: 2150.0 kg Funding Agency NASA-Office of Space Science Applications (United States) |