Ariane 5 - Heavy Payload Launch Vehicle, International

Ariane 5 is a heavy load launcher, designed to put commercial satellites into geo-stationary orbits at a low cost.

Ariane 5 is part of the European Space Agency's (ESA's) long running Arianespace programme. According to Arianespace, Ariane 5 is the first new-generation launcher to reach the commercial market, arriving at least two years ahead of its closest competitors. The stakes are also high for the European Space Agency, which has entrusted its most expensive and complex science satellite to Ariane 5.

ESA is an international organization composed of 14 EU member states, which aims to promote space research and technology and their space applications.

Arianespace is an industrial and commercial company and a world leader in the provision of commercial space transportation services. It markets and sells Ariane launch services, manages the production of the European launcher and provides launch operations from the Guiana Space Centre in French Guiana.

THRUST

Arianespace acquired 20 Ariane 5's for launch in 2001. The order covers two batches of ten, Ariane 5 launchers, out of a total of 50 heavy-lift launch vehicles to be acquired by the company under current production planning, with subsequent deliveries following at an average of eight to ten launchers per year through to early 2004.

The ESA member nations agreed to proceed with the Ariane 5's development programme in 1987 and the launcher had been designed by early 1994. In the middle of 1995, Arianespace had ordered 14 of the launchers. The first launch in 1996 exploded spectacularly, destroying the load. The first successfully completed test flight came in 1998 and the first commercial flight was successfully completed in 1999. Six Ariane 5 launches were prepared for 2000.

The vehicle consists of a main cryogenic core stage, two solid booster stages and an upper stage. The cryogenic stage is 30m high, and operates on non-toxic cryogenic propellant for just under 600s. The cryogenic stage has a propellant load of 132.27t of liquid oxygen and 25.84t of liquid hydrogen. Its Vulcain engine is ignited 7s before the launcher's lift off, allowing full monitoring during start up and stabilisation of thrust. The solid boosters propel the rocket into the orbit. The final thrust is provided by the upper stage.

Ariane 5 is the most powerful vehicle ever produced in Europe, with 1,200t of thrust. Just one of its two solid fuel boosters is more powerful than the whole of its predecessor, Ariane 4.

ARIANE 5 DEVELOPMENT

Further technological development is essential to the Ariane's continuing success. Initially, the launcher had a payload of 6,200kg. The eventual load is expected to be 12,000kg.

The most important developments affect the upper stage of the rocket. Ariane 5 Versatile is an improved version of Ariane 5's current upper stage. This is expected to enter service in late 2001, increasing the GTO payload lift capability to 7,300-8,000kg. It will be used primarily for missions to low-Earth and medium-Earth orbits. Ariane 5 ESC-A is an upper stage, which will enable Ariane 5 to place loads of 10,000-10,500kg into geostationary orbits. This is expected to begin in 2002. The Ariane 5 ESC-B will be powered by the new Vinci engine. The ESC-B will increase GTO payload performance to 11,000-12,000kg from its anticipated inception in 2006.

THE SPELTRA STRUCTURE

To accommodate its wide range of loads, the Ariane 5 launcher has adapters which are geared to different loads. The Speltra structure, which is positioned between the upper stage and the payload fairing, allows Ariane 5 to carry two primary payloads on a single flight. A 'lower' satellite is accommodated inside the Speltra, while the 'upper' payload is mounted atop Speltra and is protected by the payload fairing.

The Sylda 5 structure is housed inside Ariane 5's payload fairing, and allows the vehicle to carry two primary payloads on a single flight. During the flight, Ariane 5's upper satellite is deployed first. The Sylda 5 is then cut at its base by a pyrotechnic charge, and the structure is separated by push-off springs. The lower passenger is then ready for its deployment, completing the mission. Sylda 5 is a cylindrical-conical structure manufactured from carbon-honeycomb sandwich panels, assembled by bonded joints, and bonded and riveted aluminium frames. The ASAP platform carries mini- or micro-satellites as secondary payloads.