Book Review: The Hipparcos Satellite, the Making of History's Greatest Star Map

Abstract

THE HIPPARCOS SATELLITE The Making of History's Greatest Star Map. Michael Perryman (Springer, Berlin, 2010). Pp. xii + 282. euro30. ISBN 978-3-642-1 1602-5.The core of this book, by the science director of the Hipparcos astrometry satellite, consists of a prologue and chapters 5 to 10. These chapters explain how truly remarkable the Hipparcos mission was, and they explain it well.In the prologue Perryman describes the day of the launch, in 1989 at Kourou in French Guyana, and well captures the tension before, relief after, and excitement throughout the launch of a satellite. Many years of work hung in the balance during the hazardous process of boosting the satellite into orbit. The launch apparently was successful, but a massive setback lay in wait as the booster rocket failed to bring the satellite into a geostationary circular orbit. Many considered the mission lost. But here Perryman and his European Space Agency colleagues experienced their finest hour as they not only salvaged the mission in a very few months, by reprogramming both observations and analysis, but brought it to the initially planned level of accuracy.Remarkably, the ESA had decided to build a satellite for a branch of astronomy that was on the verge of extinction: astrometry. Perryman explains how HIPPARCOS happened in the nick of time. A decade later the field of astrometry would have shrunk into oblivion, as its practitioners aged and were not replaced with young astronomers.A small number of French astronomers initiated the concept and gradually involved a very large number of astronomers directly in the preparation of the Hipparcos mission. This group prepared the observation list, aha the Hipparcos Input Catalogue, with positions to 1 arcsec accuracy for some 120,000 stars. Even before its launch, Hipparcos had produced by far the most accurate large star catalogue!With several hundred measurements for each of 120,000 stars, an enormous system of equations had to be solved. This problem was considered sufficiently complicated that two teams were assembled to independently derive the star positions and proper motions (and for many, binary motions). When Hipparcos was conceived, the computers able to do this did not exist. After the end of the mission the two teams took several years (according to plan) to agree on the one final catalogue, which appeared in 16 volumes of print, plus 1 volume holding a completely new medium for data, CDROMs.Well into the satellite design phase, Erik H0g pointed out that data from the satellite attitude detectors could be used to produce a catalogue of two-and-a-half million stars, less accurate than the main catalogue, but still a large improvement on existing catalogues. …