VIS Flight Model during final testing. This was carried out in an ISO-5 clean area in the Euclid facilities at Airbus (Toulouse); the majority of the Euclid Payload Module is under integration behind the large black shutter. Left: the team inspecting the progress of the Full Functional Test. VIS can be seen foil-covered behind the computer screens. Right: VIS as laid out within the ISO-5 area. The foil-covered Focal Plane Array is in the background connected via 26 harnesses to the Control and Data Processing Unit which is with the Power and Mechanism Control Unit already integrated onto the Service Module Warm Panel (Fig. 6). In the foreground are the foil-covered Calibration Unit and the Shutter in a vacuum chamber. The foil coverings are in place to maintain the stringent levels of cleanliness for VIS, and the vacuum chamber is required to preserve the MoS₂ lubricant during Shutter activation.