Strengthened structure required to carry cargo payload for ISS re-supply missions

Structural loading qualification tests of the strengthened Ariane 5 upper stage that will carry the European Space Agency's Automated Transfer Vehicle (ATV) are to be completed at the end of this month.

Because of the ATV's 20,500kg (45,100lb) mass and final orbital plane, its Ariane 5 ES ATV launcher differs from the current Ariane 5 ECA in having a stronger upper-stage structure and an engine that can restart multiple times in a vacuum.

The structural tests, being carried out at EADS Casa in Madrid, are the last stage of a 30-month, €70 million ($89 million) development programme. The first ATV, named Jules Verne, is expected to be launched in May next year, delivering 7,400kg of supplies, including 840kg of water and 100kg of gas, to the International Space Station (ISS).

Ariane 5 ES 
© Ariane Space
ATV launcher variant Ariane 5 ES offers multiple restarts in a vacuum

The upper stage and engine for the first ATV flight have been manufactured over the last eight months, in parallel with the qualification tests, as ESA was convinced the designs would work. "We were confident because our designs were very conservative," says Ruedeger Albat, head of Ariane 5 development in ESA's launcher directorate.

The EADS Space-designed upper-stage engine has undergone 100 ground firings to test its restart ability at German aerospace centre DLR's Lampoldshausen facility. Following the tests, presentations on their outcome will be given within ESA and programmatic cross-checking reviews carried out.

Only the Ariane 5 ES ATV's upper stage structure and engine differ from the Ariane 5 ECA. The ES ATV uses the same solid propellant boosters and the same cryogenic main stage with the Vulcain 2 improved engine as the ECA.

In order for the ATV to reach the ISS, the Ariane will be launched from Kourou, French Guiana into a 51° orbital inclination for the first time. This has required changes to ESA's tracking stations, including a ship that has been hired to operate as a ground station out at sea.

An ATV will be launched every 15 to 18 months and remain docked to the ISS for six months, providing an extra 43m³ of crew space. At the end of its mission, the vehicle will be loaded with up to 6,500kg of waste and launched into the atmosphere to disintegrate.

Source: Flight International