SpaceX last tried to launch its Starship megarocket in November 2023, and while it made it farther than the first test, both Starship and the Super Heavy booster were lost in flight. The company has now completed the required incident review with the Federal Aviation Administration (FAA), clearing the way for another launch in the near future. The report details what went wrong with the rocket and the mitigations SpaceX has implemented to ensure it doesn't happen again.

The Nov. 18 launch was Starship's second, following a maiden voyage that incinerated the launchpad. SpaceX shielded the ground infrastructure from Starship's intense exhaust, but the vehicle still didn't reach its destination. About three minutes after launch, Starship completed a "hot staging" maneuver (above) to free itself of the Super Heavy first stage. Super Heavy was supposed to descend and land gently in the Gulf of Mexico, but it exploded just after leaving Starship behind. Meanwhile, Starship flew for a further four minutes before it, too, experienced "rapid unscheduled disassembly," as SpaceX is fond of saying.

The FAA report explains what caused both rocket stages to go up in smoke. After hot staging, Super Heavy fired 13 of its 33 Raptor engines to begin slowing its descent. However, several engines faltered, and one of them failed "energetically." SpaceX blames a liquid oxygen filter that had become clogged. The loss of inlet pressure in the oxidizer turbopumps and this sputtering led to the engine failure. SpaceX says it has already implemented hardware fixes to ensure that filter does not become obstructed in future launches.

As for Starship, SpaceX has expanded on a previous statement that put the blame on a fuel dump. Because Starship was not carrying a payload, too much liquid oxygen was on board as it reached the edge of space. To gather valid data on future payload behavior, SpaceX vented a large amount of oxygen. Unfortunately, a leak developed in the aft section of the vehicle when the oxygen was vented. This sparked a fire inside the rocket, which led to a loss of communication. Starship's autonomous control system attempted to shut down all six engines, but the "Autonomous Flight Safety System" decided Starship was too far gone and initiated a programmed self-destruct.

33 Raptor engines firing to launch Starship. Credit: SpaceX

At the time of Starship's destruction, it had reached an altitude of about 93 miles (150 kilometers), well past the transition between Earth and outer space. Its speed was a whopping 24,000 miles per hour, just shy of escape velocity (28,000 mph). SpaceX says it will implement new electronic thrust control systems in Starship to improve reliability. So, if Starship explodes again, it will be for a completely different reason.

SpaceX has four Starship vehicles waiting in the wings, but it can't launch them just yet. The FAA has accepted SpaceX's explanation of events, but there are a few regulatory hurdles yet to clear. The FAA is expected to grant Starship clearance in early to mid-March, and a third test flight should follow soon after.

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SpaceX Reveals Why Its Second Starship Exploded in Flight - ExtremeTech