From prehistoric times, mankind has looked up at the night sky, and puzzled at the changing positions of the stars. How far away they are is a question that has confounded scientists for centuries. Over the last few hundred years, many scientific careers and considerable resources have been devoted to measuring their positions and motions with ever increasing accuracy. And in the last two decades of the 20th century, the European Space Agency developed and launched the Hipparcos satellite, around which this account revolves, to carry out these exacting measurements from space.

What has prompted these remarkable developments? Why have governments been persuaded to fund them? What are scientists learning from astronomy's equivalent of the Human Genome Project? This book traces the subject's history, explains why such enormous efforts are considered worthwhile, and interweaves these with a first-hand insight into the Hipparcos project, and how big science is conducted at an international level. The involvement of amateur astronomers, and the Hipparcos contributions to climate research, death stars' passing close to the Sun, and the search for extra-solar planets and even intelligent life itself, are some of the surprising facets of this unusual space mission.

Michael Perryman has spent a career in space science focused on Europes ambitious programme to map the stars. For his scientific leadership of the Hipparcos project, the first star mapping programme carried out from space and the greatest leap in accuracy in history, he was awarded the Prix Janssen of the French Astronomical Society in 1996, and the Academic Medal of the Royal Netherlands Academy of Arts and Sciences in 1999.

Prologue: Hipparcos Launch.- Our Place in the Cosmos.- Why Star Positions?.- Early History.- Developments 18501980.- The Push to Space.- From Concept to Launch.- Disaster Unfolds.- Mission Recovery.- Science in the Making.- The Finishing Touches.- Our Galaxy.- Inside the Stars.- Our Solar System and Habitability.- The Future.- Epilogue.