The Payload Fairing ( also called Heath Shield) protects the Payload during the phases of flight as well as during the ground operations as integration and stand-by.
In particular it assures a protection against the aerodynamic flux, the thermal load during the flight and on ground integration phases and Launch Vehicle stand-by before flight, the acoustic environment and contamination.
The assembling composed by Payload Adapter, Payload Fairing and Payload constitutes the so called Payload Composite, it is integrated in a cleaning room independently from the propulsive elements of the Launch vehicle.
The fairing jettisoning is commanded when the aero-thermal flux decreases to values compatible with the Payload (as typical value around 1140 W/m2). This condition occurs just after the Z9 ignition
(approximately at 80 Km of altitude at the edge of the atmosphere).
The Payload Fairing is composed by two half-shells, with a total height close to 8 m (7880 mm) and with an external maximum diameter of 2,6 m.
The Fairing structure is a composite shell made of CFRP face sheets and of an Aluminum honeycomb core.
The fairing is jettisoned by a combined action of the Horizontal and Vertical Separation Systems commanded by pyrotechnic elements.