Mission Update: Flight 135: The last major launcher elements are integrated on Ariane 5
The Ariane 5 for Flight 135 is basically complete following this week’s integration of its vehicle equipment bay and the storable propellant upper stage.
Both elements were installed on the heavy-lift launcher on September 26 during a busy day of activity inside the integration building at Europe’s Spaceport.
The vehicle equipment bay was integrated first, having been hoisted to the upper levels of the launcher integration building by an overhead crane system, and then lowered into position.
Often referred to as launcher’s "brains," the vehicle equipment bay houses the basic electronic equipment required for flight control, guidance and power distribution. The equipment bay is a large structure – 5.46 meters in diameter and 1.56 meters high – and is nearly three times heavier than the one used on Ariane 4.
Ariane 5’s vehicle equipment bay contains the launcher’s flight control unit, power distribution system, flight safety unit and telemetry system. It also houses the hydrazine-fueled attitude control system, which provides roll control during flight of the main cryogenic stage and the storable propellant stage, as well as three-axis control during all positioning maneuvers for satellite deployment.
With the vehicle equipment bay in position atop the Ariane 5, the storable propellant upper stage was then raised for its integration on the launcher.
The upper stage fits into the vehicle equipment bay, and it propels the satellite payload into the desired orbit for separation at the mission’s completion. Powered by an Aestus re-ignitable engine, the upper stage has the longest burn time of any Ariane 5 propulsion system.
Ariane 5’s upper stage operates on hypergolic propellant, which is fed from four pressurized tanks.
The necessary connections and hook-ups for the upper stage and vehicle equipment bay were performed during the rest of this week on the Ariane 5, bringing the vehicle closer to a launch-ready condition.
