Ariane 5 production. Engineers supervising the welding of a fuel tank for an Ariane 5 launcher. The tank is made of 3mmthick aluminium. The welding device (starshaped object at centre) rotates inside the tank, allowing a continuous, seamless weld to be made. The integrity of the weld is crucial, as the cryogenic tanks form the loadcarrying structure of the first stage of the launcher. The stage contains two tanks, one for liquid hydrogen and the other for liquid oxygen, sharing a common bulkhead. The interior of the liquid hydrogen tank is seen here. Photographed at the Cryospace factory, Les Mureaux, France.