Nozzle Defect Responsible For Ariane 5 Launch Failure

Arianespace hopes to have its enhanced Ariane 5 rocket back in service during the second half of this year. This follows the release of an inquiry board’s results into the cause of the failure of Arianespace flight 157 in December.

A leak in the Vulcain 2 engine’s nozzle’s cooling circuit during the first phase, which led to a critical overheating of the nozzle, was the main factor behind the launch failure. The nozzle’s deterioration led to a major imbalance in the thrust of the Vulcain 2 engine. This led to a loss of control over the launcher’s trajectory.

Flight 157 was carrying Eutelsat’s HOT BIRD 7 satellite and Stentor, a space telecoms and technology demonstrator satellite for French space agency CNES. Flight 157 was the first launch of the enhanced Ariane 5 capable of carrying a 10 tonne payload. Its subsequent failure is a huge blow for Arianespace.

The inquiry board has made a number of recommendations that Arianespace has accepted as it tries to overcome the failure of flight 157:

• Modification of the Vulcain 2 nozzle, taking into account experience acquired with the Vulcain 1 engine nozzle,
• Assessment of possibilities for simulation during ground tests of loads observed during actual flight on the Vulcain 2 engine
• Enhancing of the quality of flight equipment.

–Mark Holmes