again as not technically required. More than once the responsibilities for fabrication were bartered to one international partner and then another in exchange for Shuttle launch services and resources that the United States would provide on board the station in orbit. The Cupola made the rounds to Brazil and then finally wound up with ESA and the Italians in 1998, who completed it in 2003. Even then, the launch of the Cupola was repeatedly delayed until it finally made it into orbit in February 2010. The delivery method also changed from the Cupola being mounted on a SpaceLab pallet accompanying Kibo'''s external facility to being mounted on the European built Tranquility module as it was delivered. The original barter agreement had ESA building two cupola modules for the ISS. This was later amended to just one. The ESA-built Tranquility module and the Cupola together cost nearly $409 m. With final design and assembly by the Italian contractor Alenia Spazio (now Thales Alenia Space), it is nearly 3 metres in diameter and 1.5 metres tall. It has six side windows and a top window, all of which are equipped with shutters to protect them from damage by micrometeoroids and orbital debris. It features a thermal control system, audio, video and MIL-STD-1553 bus interfaces, as well as the connections needed for installing one of the two identical workstations that control the robotic manipulator Canadarm2. The Cupolas outer framework is made from forged aluminum, with an inner skeleton made from steel plates and bars welded together; which add strength against the pressure. Several companies including Alcoa and Tata Steel Europe were contracted for the manufacturing. Each window is composed of 4 separate layers ('panes'): An outer debris pane, two 25 mm pressure panes, and an inner scratch pane. Each pressure pane and debris pane is made from fused silica glass. The panes can be replaced in-orbit after an external pressure cover has been fitted. The window shutters are manually controlled. Each window has a knob with a direct mechanical linkage to the outside shutter assembly. O-rings are used to prevent air leakage. Installation Cupola was launched aboard Space Shuttle Endeavour on mission STS-130, on 8 February 2010. It was berthed to the forward port of the Tranquility module for launch, and was later transferred to the nadir-facing port of Tranquility by the Canadarm2, once Tranquility had been berthed to the Unity Module of