This week the Independent Enquiry Commission (IEC), set up by ESA and ArianeSpace, released their findings and future roadmap after the loss of the VV17 mission. The launch had failed back on November 17, resulting in the loss of the two payloads on board. The loss also came on only the second flight after another Vega loss in July 2019.
The two Vega losses have been proven to be unrelated. The failure in 2019 occurred on the second stage of the vehicle while the most recent failure occurred on the AVUM fourth stage. Using available flight data, the trouble was narrowed down to the AVUM’s Thrust Vector Control (TVC). TVC is the control system that points the engine nozzle in different directions to steer the craft while the engine is running. Investigators found that the trouble was not in how the system was designed, but instead with how this particular one was built.
In general terms, the TVC system was wired in backwards so that commands to steer the vehicle one direction would result in it going the opposite direction. The onboard computers tried to correct, and as more overcorrection was needed, vehicle control was lost leading to mission failure.
The IEC’s findings outlined the steps of the problem starting with “a misleading integration procedure” that led to “an inversion of electrical connections” which was not detected during any testing phase. The IEC laid out plans for corrections on existing hardware and on future launchers that will be built. Teams are already working on checking existing launchers that are already built for the next two launches. For launchers yet to be built, the new processes will be implemented immediately.
Of surprising note, the IEC says that these fixes and tests can be completed quickly enough to keep Vega on schedule with its next launch coming toward the end of Q1 2021.