TOULOUSE, France---Astrium has delivered the first qualification model of the new vehicle equipment bay (VEB) for the Ariane 5 heavy launcher with the new ECA cryogenic upper stage, scheduled to make its first flight in mid-2002.
The new VEB was developed for the Ariane 5 Plus launcher upgrade program, led by French space agency CNES on behalf of the European Space Agency (ESA). The VEB will be shipped to the launch site at Kourou, French Guiana, for integration on the fuelling model, which is designed to validate, right at the launch pad, the chilldown and liquid oxygen and hydrogen fuelling operations for the new ESC-A stage developed by Astrium at Bremen, Germany. Validation tests will provide a consolidated analysis of all thermal, mechanical and electrical characteristics of the new launcher stages.
At the same time, the new VEB will be undergoing a series of qualification tests in Toulouse to test its reactions to the different conditions it will face during the mission: acoustic vibration, thermal and radiation, separation shocks. Once qualified, the ECA equipment bay will be produced in volume as part of the P2 production batch for Ariane 5 launchers. This new production series will provide customers with several key benefits:
--Improved performance and operational flexibility starting in mid-2002, in particular payload capacity for a dual launch into GTO increasing from 6 to 10 tons, and missions involving multiple in-flight restarts, lasting up to six hours.
--Reduction in launcher cost of approximately 35%.
The P2 batch will include three types of equipment bays:
--10 ECA type VEBs, adapted to Ariane 5s new cryogenic upper stage (ESC-A), which will boost the launchers payload capacity for a dual launch into GTO to nearly 10 tons.
--3 P1+ VEBs, which extend the current series. They feature an optimized structure that will add over 100 kg to the payload capacity, a new separation system for an attenuated dynamic environment during operation, and new electrical equipment which offers higher performance and lower cost h
--7 new ES VEBs, similar to the first three, but adapted to Ariane 5s multiple orbit versatile mission profile. They will support up to five re-ignitions of the engine in the storable propellant upper stage, and operating time in orbit of up to six hours. In this version, the launcher payload capacity for a dual launch into GTO will increase to more than 7 tons.
The Ariane 5 vehicle equipment bay handles all flight control and command tasks for the launcher.
Flight control commands are calculated by the onboard computers and specialized electronics, based on speed and attitude information provided by the guidance systems. These computers also send all commands needed for launcher operation, such as engine ignition, stage separation and release of payloads. A telemetry link sends a continuous stream of data up to a million bits per second to the ground.
The functional electrical system is fully redundant: all equipment items have an identical backup.
A hydrazine thruster-based attitude and orbit control system (AOCS) on the P1+ and ES model VEBs for the storable propellant upper stage steers the launcher during the different flight phases. A cutting system separates the upper part of the launcher, which injects satellites into their final orbit, from the main cryogenic stage once the main stage Vulcain engine has finished its task.
The vehicle equipment bay is a cylindrical structure measuring 5.4 meters in diameter, and 1.12 to 1.56 meters high, depending on the version used. Empty weight (without propellants) is from 1,000 to 1,400 kilograms.
Since Astrium started space operations in Toulouse more than 25 years ago, it has turned out nearly 160 vehicle equipment bays - a clear demonstration of the technical expertise of its teams. Astrium is responsible for most of Ariane 5's upper stage: in addition to the VEB, Astrium's Bremen plant is in charge of the EPS storable propellant and ESC-A cryogenic stages, the Friedrichshafen plant produces the Speltra and Sylda payload structures, and the
The Stevenage plant produces the auxiliary payload structures (ASAP5).
