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On May 15, 2021, Rocket Lab's Electron failed in the "Running Out of Toes" mission. The first stage had a nominal flight. Then, from looking at the launch video published by Rocket Lab, the second stage appeared to ignite and then shut down, and never relight. What happened and why?

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From a Rocket Lab's press release (emphasis added):

The review concluded that an issue occurred within the second stage engine igniter system almost three minutes and 20 seconds into the flight. This induced a corruption of signals within the engine computer that caused the Rutherford engine’s thrust vector control (TVC) to deviate outside nominal parameters and resulted in the engine computer commanding zero pump speed, shutting down the engine.

The igniter fault resulted from a previously undetectable failure mode within the ignition system that occurs under a unique set of environmental pressures and conditions. The issue was not evident during extensive pre-flight testing for this mission, including more than 400 seconds of burn for this particular engine, more than 1,500 Rutherford engine hot fires to date, and 17 successful orbital launches. Rocket Lab has since been able to reliably replicate the issue in testing and has implemented redundancies in the ignition system to prevent any future reoccurrence, including modifications to the igniter’s design and manufacture.

The anomaly review confirmed that Electron’s first stage performed flawlessly during the mission and did not contribute to the flight issue.

The corrupted signal could have come from a connector being miss-seated during flight, or by other means.

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    $\begingroup$ What was different in this mission that all of the other before it that caused the failure? $\endgroup$ May 6, 2022 at 13:46
  • $\begingroup$ It sounds like it was more a design issue than something like a mis-seated connector. It was something "that occurs under a unique set of environmental pressures and conditions". A loose connector would cause issues regardless of those conditions. $\endgroup$ May 6, 2022 at 14:22
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    $\begingroup$ @ChristopherJamesHuff alternatively "a unique set of environmental pressures and conditions" could un-seat a connector, though the ability to unseat can still be the design issue $\endgroup$ May 6, 2022 at 14:24
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    $\begingroup$ @Starshipisgoforlaunch it could be any number of things. For example, it could have been corona discharge through a gap in insulation due to low-pressure air at high altitude, with the discharge simply not causing problems on previous flights, or not occurring because manufacturing variations closed the gaps. $\endgroup$ May 6, 2022 at 14:25
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    $\begingroup$ Does Rocket Lab know/ slash have any educated guesses? @ChristopherJamesHuff $\endgroup$ May 6, 2022 at 19:31

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