Why 4 engines shut down prematurely during Booster 9's static fire?

Saturday, August 12, 2023 | Chimniii Desk

On August 7, 2023, SpaceX conducted a static fire test of Booster 9, the first stage of the Starship Super Heavy rocket. The test was intended to simulate the conditions of a launch, but it was aborted after just 2.9 seconds when 4 of the 33 Raptor engines shut down prematurely.

Advertisement

SpaceX has not released any specific information about why the engines shut down. However, there are a few possible explanations:

Combustion instability: This is a condition that can occur in rocket engines when the fuel and oxidizer do not mix properly. This can lead to vibrations and oscillations that can damage the engine or cause it to shut down. Combustion instability is a known issue with the Raptor engine, and SpaceX has been working to address it.
Sensor problems: The engines on Booster 9 are equipped with a variety of sensors that monitor their performance. If one of these sensors malfunctions, it could send a false signal to the engine control system, causing the engine to shut down.
Software problems: The engine control system on Booster 9 is a complex piece of software. It is possible that there was a software bug that caused the engine to shut down prematurely.

It is also possible that a combination of factors caused the engines to shut down. SpaceX is likely still investigating the issue, and they will hopefully release more information about the cause of the premature shutdowns in the future.

Advertisement

It is important to note that Booster 9's static fire was still considered a success, even though 4 engines shut down prematurely. The remaining 29 engines performed as expected, and the test provided valuable data for SpaceX's engineers. Booster 9 is still scheduled to launch on its first orbital test flight in the coming months.

Advertisement

Here is a more detailed look at each of the possible explanations for the premature engine shutdowns:

Combustion instability: Combustion instability is a complex phenomenon that can be caused by a variety of factors, including the mixing of the fuel and oxidizer, the design of the combustion chamber, and the operating conditions of the engine. In the case of the Raptor engine, combustion instability is thought to be caused by the high combustion chamber pressures and temperatures. SpaceX has been working to address combustion instability by developing new combustion chamber designs and by using more advanced materials in the engine.
Sensor problems: The engines on Booster 9 are equipped with a variety of sensors that monitor their performance. These sensors include temperature sensors, pressure sensors, and vibration sensors. If one of these sensors malfunctions, it could send a false signal to the engine control system, causing the engine to shut down. SpaceX has a rigorous testing program for its sensors, but it is always possible that a sensor could malfunction during a test.
Software problems: The engine control system on Booster 9 is a complex piece of software. This software is responsible for monitoring the performance of the engines and for controlling the engines' operation. If there is a software bug in the engine control system, it could cause the engine to shut down prematurely. SpaceX has a team of software engineers who are responsible for testing and debugging the engine control system. However, it is always possible that a software bug could be introduced into the system during development or testing.

It is also possible that a combination of factors caused the engines to shut down. For example, it is possible that combustion instability caused the sensors to malfunction, which in turn caused the engine control system to shut down the engines. SpaceX is likely still investigating the issue, and they will hopefully release more information about the cause of the premature shutdowns in the future.

Advertisement

The premature engine shutdowns during Booster 9's static fire are a setback, but they are not a major cause for concern. SpaceX has a long history of successfully resolving issues with its rockets, and they are confident that they will be able to fix the problems with Booster 9. Booster 9 is still scheduled to launch on its first orbital test flight in the coming months, and SpaceX is confident that the rocket will be successful.