|Ariane 5 ECA|
|Launch vehicle||Ariane 5 ECA|
|Launch site||Kourou, French Guiana|
|Description||First stage failure|
|Cause||Vulcain 2 engine design flaw|
|Payload||Hotbird 7 (television satellite), STENTOR (experimental communications satellite)|
|Desired orbit||Geostationary transfer orbit|
From T+2:58 to T+3:06, "the engine speed changed and a significant flight control perturbation occurred," Arianespace said shortly after the failure.
At T+3:07, the Ariane 5's payload fairing was jettisoned as planned, but the launch vehicle's attitude was not correct. "The manoeuvre of fairing jettisoning should happen when the launch vehicle has an attitude and trajectory which are as stable as possible. During jettisoning of the fairing, the trajectory and the attitude were not stabilised," Arianespace CEO Yves Le Gall said.
"The launch vehicle subsequently demonstrated erratic behaviour," Arianespace stated rather euphemistically in a press release. As a matter of fact, it lost control at an altitude of about 150 km and started falling back to the ground.
In compliance with range safety procedures, the launch vehicle was destroyed at approximately 7 minutes and 36 seconds into the mission. By that time, the Ariane 5 had dropped down to an altitude of about 69 km at a distance of 800 km off the coast of French Guiana.
In January 2003, Swedish company Volvo Aero acknowledged that the engine nozzle it supplied for the Ariane 5 ECA was the cause of the new rocket's failure. Company spokesman Fredrik Fryklund said that "we will not try to shift blame away from ourselves," adding that "it was the first launch of a rocket with a dramatically increased lifting capacity. What happened is unfortunate, but that's the name of the game when you take new steps."
The inquiry board into the Ariane 5 ECA failure had pinpointed a defect in the cooling system of the rocket's first-stage Vulcain 2 engine as root cause for the loss of the rocket and the two satellites it carried. The board said that it identified the occurrence of a leak in the Vulcain 2 nozzle's cooling circuit during the first flight phase. Wolfgang Koschel, who chaired the board, said small fissures occurred in the Vulcain 2 nozzle's cooling tubes that were the result of mechanical and thermal loads experienced during flight.
As a result, the nozzle overheated, leading to the loss of its integrity and a major imbalance in thrust. So far, the solid boosters had provided 92 percent of the thrust, but when they were separated only the asymmetrical thrust of the main engine remained. Control over the launch vehicle's trajectory was then completely lost.