Fully integrated Gaia payload module with nearly all of the multilayer insulation fabric installed. Nearest to the camera, the rear of one of the primary mirrors and one of the tertiary mirrors are visible. Beneath the tertiary (smaller) mirror, the Radial Velocity Spectrometer can be seen. To the right is the Focal Plane Assembly with its charge-coupled device sensors (blue). The focal plane array, with a total of almost a billion pixels, is the largest ever developed. The integration was carried out at Astrium, Toulouse.