Gaia CCD, Gaia originally stood for Global Astrometric Interferometer for Astrophysics. As the project evolved, it became clear there would be more to Gaia than just interferometry. Gaia is to create the largest and most precise three dimensional chart of our Galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our Galaxy and throughout the Local Group.

http://www.esa.int/esaSC/SEMC7L1DU8E_index_0.html
http://www.sharecast.com/cgi-bin/sha...tory_id=492947
http://sci.esa.int/science-e/www/obj...objectid=37532

Gaia will be placed in an orbit around the Sun, at a distance of 1.5 million kilometres further out than Earth. This special location, known as L2, will keep pace with the orbit of the Earth. Gaia's goal is to perform the largest census of our Galaxy and build a highly accurate 3D map. The satellite will determine the position, colour and true motion of one thousand million stars and over 100,000 objects in our Solar System. Gaia will also identify as many as 10,000 planets around other stars. To accomplish this ambitious task, Gaia requires the largest focal plane of charged couple devices (CCDs) ever built for space application. Gaia's measurements will be so accurate that if it were on the Moon, it could measure the thumbnails of a person on Earth.