Cryogenic upper stage (ESC-A) A new more powerful cryogenic upper stage has been developed for the Ariane 5 ECA launcher configuration. It is referred to as the ESC-A stage from its title in French, Etage Supérieur Cryotechnique de type A.
The ESC-A stage reuses the reliable HM-7B rocket engine implemented on the third stage of the Ariane-4 launcher. Its mission is to provide the necessary complementary energy to reach the target orbits. The stage also provides roll control during the propulsion phase and during the separation sequences of the payloads.
The ESC-A stage is composed of:
- two cryogenic tanks (one for liquid hydrogen, the other for liquid oxygen) containing 14.7 tonnes of ergols
- the HM7B engine which operates for nearly 940 s and delivers a thrust in vacuum of 6.5 tonnes
Vehicle Equipment Bay C (VEB-C)
Modifications were also introduced on the Vehicle Equipment Bay (VEB) used for the Ariane 5 Generic version.
The new VEB has been adapted to the A5 ECA configuration:
- it operates in a “cryogenic” environment
- it does not support any more the EPS stage in its middle volume
- it no longer needs to carry the attitude control system (SCA) as that function is now provided by the ESC-A stage itself
- it is made, as before, in composite material, but it is smaller and lighter
- it reuses the electrical equipments of the Ariane 5 Generic Plus version
A conical adaptor structure has been developed and mounted on top of the VEB-C structure to provide at its upper interface the Ariane standard diameter of 2624 mm where the payload adaptor is fixed.
Changes at Europe’s Spaceport
To accommodate this larger version of the Ariane 5 several changes have been made to the equipment and facilities at Europe's Spaceport. For instance, the new upper stage of the Ariane 5 ECA makes the launcher taller so the roof of the Ariane-5 Final Assembly Building has been raised by more than four metres.
The launch tower has also been adapted to fit the height of the new launcher and the arms that carry the propellant feed lines and electrical connections to the launcher's new upper stage.
Last update: 2 December 2005