On Tuesday, November 17, Arianespace announced the loss of the Vega VV17 mission, which was carrying two payloads, SEOSAT-Ingenio, an Earth-science observation satellite for the European Space Agency (ESA), on behalf of Spain’s Center for Development of Industrial Technology (CDTI), and TARANIS for France’s National Centre for Space Studies (CNES).
The first three stages functioned nominally until the ignition of the AVUM upper stage, eight minutes after liftoff. At that time, a degraded trajectory was detected, followed by a loss of control of the vehicle and the subsequent loss of the mission.
Initial investigations, conducted directly after the launch with the available data, identified a problem related to the integration of the fourth-stage AVUM Thrust Vector Control (TVC) system as being the most likely cause of the loss of control of the launcher.
Arianespace (the launch service provider) and the European Space Agency (ESA – the launch system development authority) immediately set up an Independent Enquiry Commission (IEC). The Commission provided the detailed report and conclusions confirming initially identified root causes to the failure, comprehensively explaining what went wrong in the integration process and why the error was not detected before flight. According to its findings, the Commission has accordingly formulated a road map for a robust Vega return to flight.
More precisely, the IEC concludes that the VV17 cause of failure is not attributable to a flaw in the qualification of the design but to the wrong routing and connection of the control lanes of the electro-mechanical actuators of the AVUM upper stage Thrust Vector Control (TVC) system, inverting steering commands and causing trajectory degradation leading to the loss of the vehicle.
The detailed series of causes are described as (i) a misleading integration procedure causing (ii) an inversion of electrical connections, not detected through (iii) the different control steps and tests executed between the integration of the AVUM upper stage and the final acceptance of the launcher due to some inconsistencies between specific requirements and prescribed controls.
A comprehensive set of both immediate and permanent recommendations has been presented by the IEC to ensure safe and prompt return to flight, as well as to ensure launch vehicles reliability on the long term. The first set of recommendations include additional inspections and tests on the next two Vega launchers, whose hardware is already totally or partially produced, and workmanship.
Permanent recommendations have been proposed to further mitigate the identified root causes, regarding the manufacturing, integration and acceptance processes on Vega assembly lines in Italy and its final acceptance in French Guiana.
Starting this week, a task force steered by ESA and Arianespace has started implementing the roadmap proposed by the IEC and will thoroughly follow its implementation. A set of actions will be implemented by Vega’s prime contractor Avio, under the supervision of Arianespace, as launch service provider, and ESA, as launch system development authority, in order to make possible the next Vega launch, VV18, still scheduled by Q1 2021 from French Guiana, and the following ones.
