We have an update on Astra’s ELaNA 41 mission. This particular launch failed on February 10th, 2022, shortly after the first stage cut off, due to an apparent fairing separation failure, and Astra now thinks they know what happened.

The fairing separation system consists of five mechanisms that are triggered by electrical signals which occur rapidly in series to separate the two halves of the fairing from each other and from the rocket’s first stage. The problem with LV0008’s fairing separation mechanism was that its wiring harness, which sends commands from the computer to different parts of the vehicle, was designed incorrectly. This resulted in one of the separation systems being initiated in the wrong order so that the last one never got its command to fire, causing the fairing to not separate.

Astra has redesigned the harness on vehicles currently being built and has come up with a new test to catch similar errors in the future.

During the failure investigation, Astra also discovered a separate software issue that prevented the upper stage from gimballing its engine and recovering from the tumble due to its bad separation. The flight software sent a signal to start that system, but somewhere in between the computer and the engine, that signal got corrupted or lost, resulting in what is called packet loss. According to the report: ...an unlikely combination of factors [this] caused a failure that we didn’t predict.

Astra has been able to replicate this issue on their hardware simulator and modify their systems to reduce the chances of this happening again. Astra attributed these rapid fixes to the fact that they are constantly iterating on their hardware, which is designed to be simple and cheap to produce, so it’s relatively easy to implement fixes like these.

More Information

Astra press release