NEW ARIANE 5 VEHICLE EQUIPMENT BAY UNDERGOES QUALIFICATION TESTS

Toulouse – Astrium has started qualification tests on the first of three new vehicle equipment bays (VEB) developed for the Ariane 5 Plus programme. This launcher upgrade programme is led by French space agency CNES on behalf of the European Space Agency (ESA).

The tests are being conducted on a flight-standard VEB at space testing specialist Intespace, and incorporate adjacent launcher structures and an engineering model of Eurostar 3000, a new 5-tonne-class communications satellite platform developed by Astrium. The goal is to test this set of equipment, which represents the upper part of the future launcher, in different mission environments, including acoustic vibrations, radiation, thermal and separation shock. One of the primary objectives of these tests is to demonstrate that the new VEB, with its optimised structure and new pyrotechnic separation system, provides the specified performance.

Once qualified, this equipment bay will be produced in volume as part of the P2 production batch for Ariane 5 launchers. The aim of this new production series is to provide customers with several key benefits:

· Improved performance and operational flexibility starting in 2002, in particular payload capacity for a dual launch into GTO increasing from 6 to 10 tonnes, and missions involving multiple in-flight restarts, lasting up to six hours. · Reduction in launcher cost of approximately 35%.

For the VEB, which is the “brains” of the launcher, this means a P2 production run of 20 revamped units combining higher performance and lower cost.

The P2 batch will include three types of equipment bays, with the first scheduled for lift-off in May 2002:

· 3 VEBs which extend the current series. They feature an optimised structure that will add 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. · 7 new VEBs, similar to the first three, but adapted to Ariane 5’s multiple orbit “Versatile” mission profile. They will enable up to five re-ignitions of the engine in the storable propellant upper stage, and support operating time in orbit up to six hours, compared with less than an hour today. In this version, the launcher’s payload capacity for a dual launch into GTO will increase up to 7 tonnes. It is this version of the VEB that is now being tested in Toulouse. · 10 redesigned VEBs, adapted to Ariane 5’s new cryogenic upper stage (ESC-A), which will boost the launcher’s payload capacity for a dual launch into GTO to 10 tonnes. This version will also be qualified in 2001.

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 specialised electronics, based on speed and attitude information provided by the guidance platform. 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 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 delivers satellites to 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 metres 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 150 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 Stevenage plant produces the auxiliary payload structures (ASAP5).