SpaceX has revealed the cause of Starship anomalies that were responsible for delays from the FAA

Three months after the preliminary launch of the Starship carrier rocket, which ended in a loss during the final phase of the rocket's flight and the booster stage, the Federal Aviation Administration (FAA) has completed its investigation of the incident.

SpaceX has identified and FAA has accepted the primary causes and 17 corrective actions documented in SpaceX's incident report. Before the next SpaceX launch, all corrective actions must be completed and SpaceX must obtain a modification of the license from the FAA that takes into account all safety, environmental protection, and other applicable regulatory requirements.

— said the federal agency in a statement.

SpaceX still needs to provide additional information to the FAA about responsibility for the safety of people and property on the ground before the agency completes the review of the application for the third launch of Starship. The likely timeframe for completing the regulatory process is early to mid-March, ArsTechnica reports.

What went wrong

SpaceX noted that the first stage of the Super Heavy rocket performed nominally, with all 33 Raptor engines igniting successfully. Then the carrier rocket completed a full burning cycle to achieve stage separation. At this point, the booster stage performed a "hot exit" maneuver, during which the Starship stage detached from the booster while some booster engines were still running.

The next step for the Super Heavy was to perform a series of ignitions for a soft landing in the Gulf of Mexico. During the first test, 13 rocket engines were supposed to ignite. However, several engines started to shut down before one engine failed, quickly leading to the unplanned destruction of the carrier rocket.

Subsequently, the issue was linked to a problem with supplying liquid oxygen to the Raptor engines. The most likely root cause of the booster's Rapid Unscheduled Disassembly (RUD) was identified as a filter blockage through which liquid oxygen is supplied to the engines, leading to a loss of inlet pressure in the oxidizer turbopumps of the engines and eventually resulting in the failure of one of the engines, causing the loss of the spacecraft.

Starship Vent Outlets

The spacecraft was supposed to fly almost two-thirds of the way around the Earth before falling near the Hawaiian Islands. However, about seven minutes after liftoff, a large release of liquid oxygen occurred. According to SpaceX, there was an excess of liquid oxygen on board for collecting data needed for future payload deployment missions. It had to be released before Starship fell.

A leak in the aft part of the spacecraft, caused by the launch of liquid oxygen ventilation, led to fires and subsequent fires, resulting in the loss of communication between the spacecraft's onboard computers and the command shutdown of all six engines until the end of the ascent burn, after which the flight safety autonomous system detected a flight rule violation and activated the flight termination system, leading to the breakup of the spacecraft.

— the company stated

By the time the spacecraft reached a height of 150 km, it had reached a speed of about 24,000 km/h. This is slightly below orbital speed, which is 28,000 km/h.

In its statement, SpaceX reported that it is making changes to the Super Heavy and Starship stages to address these issues. The company is also aiming to improve the overall performance of the Starship by adding a new thrust vector control electronic system for the Raptor engines of the upper stage of the Starship and a faster fuel loading system before launch.

SpaceX has four Starship spacecraft in the final or near-final stages of construction. If the next flight goes smoothly, the company may begin launching the world's largest rocket more frequently.