The Planck spacecraft mated with its launcher
Still attached to the arms of the vertical lifting device, this image was taken just after mating of the Planck spacecraft on top of the Ariane 5 ECA launcher. The golden-yellow ring attached to the base of the spacecraft's service module is the launcher adapter ring (Adaptateur Charge Utile, or ACU).
The ACU has a diameter of 2.624 m and is secured to the launcher through a 0.78m-high adapter cone, composed of a strong carbon structure and two aluminium rings. Seen running as an iris around the adapter cone is the top of the Vehicle Equipment Bay (VEB).