Ariane 5 fuel tank

The core cryogenic stage of the second Ariane 5 launch vehicle hoisted in the Launcher Integration Building at the Ariane Launch Complex 3 (known as ELA-3) at Europe's Spaceport in French Guiana on 10 August 2004.

This stage carried 173 tonnes of propellant and was powered by a Vulcain 2 engine, which delivered 20% more thrust than the original Vulcain 1. The second Ariane 5 ECA mission (V164), was launched on 12 February 2005 and two satellites were lofted to orbit: XTAR-EUR, a secured communication satellite operated by XTAR LLC , and ESA's Sloshsat-FLEVO experimental satellite to investigate propellant sloshing in orbiting spacecraft. A satellite mock-up, MaqSat B2, was also flown but not released to reduce orbital debris.

The Ariane 5 ECA was a major upgrade of the Ariane 5 design to increase its payload capacity to geostationary transfer orbit to 10 tonnes. The Ariane 5 program was decided by ESA in 1987 to provide a successor to the initial Ariane 1 to 4 series of vehicles in order to ensure continuity of Europe's guaranteed access to space. The development programme was delegated to France's space agency CNES. Ariane 5 was introduced in 1996 and became operational in 1999 with Arianespace taking over commercial operations on behalf of ESA.