GAIA basic angle monitoring system

GAIA 1 is a global space astrometrymission, successor to the Hipparcos mission, launched in 1989. The GAIA spacecraft is being built by EADS Astrium France and is scheduled for launch in 2013. At a distance of 1.5 million km from Earth at Lagrangian pointL2, slowly spinning around its axis, GAIA will monitor each target star about 100 times over a 5- year period, precisely measuring its distance, movement, and change in brightness. Through spectrophotometric classification, it will provide the detailed physical properties of each star observed: luminosity, temperature, gravity, and elemental composition. This massive stellar census will provide the basic data to tackle an enormous range of important questions related to the origin, structure, and evolutionary history of our Galaxy. The measurements performed with GAIA will be accurate to 24 microarcsec, about 100 times more accurate than Hipparcos. To achieve this extreme accuracy at an operational temperature of 100 K, the entire GAIA Payload is made out of Silicon Carbide (SiC).