The Gaia Astrometry Mission: Status after CDR Completion

Gaia is an ESA science cornerstone mission, which relies on the proven principles of ESA's Hipparcos mission to solve one of the most difficult yet deeply fundamental challenges in modern astronomy: to create an extraordinarily precise three-dimensional map of about one billion stars aiming at star magnitudes down to 20 throughout our Galaxy and beyond. In the process, it will map the motion of the stars, which encodes the origin and subsequent evolution of the Galaxy. Through comprehensive photometric classification, it will provide the detailed physical properties of each star observed: characterizing their luminosity, temperature, gravity, and elemental composition. This massive stellar census will provide the basic observational data to tackle an enormous range of important problems related to the origin, structure, and evolutionary history of our Galaxy. To achieve Gaia’s challenging mission goals, the spacecraft contain a number of novel design solutions. Astrium SAS in Toulouse has been awarded the contract to build the Gaia spacecraft in Spring 2006. Since then the program has successfully completed the design and development phase and is now in the integration and verification phase of the flight model. This paper describes the Gaia mission, focusing on the main spacecraft design features as well as on the status of the Gaia mission.