Project HIPPARCOS

The HIPPARCOS satellite project of the European Space Agency is described in detail. The paper focusses on the basic rationale, on the performance of the scientific instrumentation and on an explanation of how scientific objectives can be achieved. The purpose is to provide quantitative visibility of basic project features to astronomers and astrophysicists not familiar with astrometric techniques by exploiting updated technical information on project parameters not generally available in the open literature.Communication presented at the International Conference on Astrometric Binaries, held on 13–15 June, 1984, at the Remeis-Sternwarte Bamberg, Germany, to commemorate the 200th anniversary of the birth of Friedrich Wilhelm Bessel (1784–1846).