HIPPARCOS
In 1989 ESA launched the High Precision Parallax Collecting Satellite (HIPPARCOS) for the purpose of compiling an accurate catalog of stellar positions. Although a launch malfunction left the 1.14 metric ton satellite stranded in GTO instead of the intended GEO, ESA engineers and space scientists were able to salvage much of the program's objectives despite the less than optimum conditions. By 1992, precise astrometric measurements of 120,000 stars had been made with the desired accuracy of two milli-arcseconds under the Main Experiment, and a mission extension had been granted. A secondary objective, code-named the Tycho Experiment, called for obtaining positional data (30 milli-arcsecond accuracy) and two-color photometric properties of 400,000 additional stars. The mission was terminated on 15 August 1993 (References 223-227).
The HIPPARCOS satellite's basic structure was a hexagonal box with three rectangular solar panels extending from the base. The spacecraft maintained a very slow spin rate (~ one revolution every two hours) to facilitate its all-sky mapping mission. At the end of its mission the orbital parameters of HIPPAR-COS were about 490 km by 35,880 km at an inclination of 6.8 degrees. Matra Marconi was the prime contractor for the satellite with significant contributions from the major European aerospace industries, including Dornier, Fokker, ERNO, and British Aerospace.
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