Daniel Mugnier, launch operations director at Kourou in French Guiana, said that 37 seconds into the mission the onboard computer apparently started to believe - wrongly - that the rocket was veering off course and therefore issued a command to the rocket motors.
The control system swivelled the nozzles of the rocket engines so violently that they hit the end-stops; the rocket turned over and the stresses broke off the upper part, triggering automatic self-destruction.
In Britain, scientists were putting a brave face on the damage to their research programmes following the loss of the four-satellite Cluster payload carried on Ariane-5. At ESA headquarters, the focus was moving to the contractors and the pre-flight tests. The agency's inquiry is due to make its first report by 15 July. Launch-pad prospects, page 21Reuse content