Vega launch failure caused by thermo-mechanical failure of dome part of Zefiro-23 second stage but exact mechanism remains a mystery

by | Sep 9, 2019 | ESA, Launches, Military space

An investigation has revealed the cause of the Vega launch failure on flight VV15, which lost the Falcon Eye 1 satellite causing an insurance loss of circa US$416 million. The sudden “violent” anomaly occurred after what appeared to be a successful launch from the Kourou Space Centre, at 0153 GMT on 11 July 2019. At T+130s, after separation of the first stage and ignition of the Zefiro 23 second stage which burned for 14 seconds, the failure caused the remaining rocket to break into two parts – the Zefiro 23 second stage and the third stage with attached AVUM upper stage.

The Avio-built rocket, operated by Arianespace, was detected as having an anomalous trajectory at T+135s. The rocket parts and Falcon Eye 1 Earth Observation satellite for the UAE Defence Forces did not achieve orbit and fell into the Atlantic Ocean. A neutralising range-safety destruction command was sent to the remains at 213s into the flight. At 314s telemetry data and signals ceased.

An investigating commission found that the cause was a thermal-structural failure of the forward dome area of the Zefiro-23 solid rocket stage. While the exact failure mechanism has not been determined, it is suspected that a manufacturing error was behind the fault. Checks and corrective actions are being implemented to allow flights of the Vega rocket to resume in early 2020.

Diagram of the Vega rocket. Courtesy: ESA

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