The Last Two Starships Exploded in a Similar Way, Almost at the Exact Same Time. The Twist: The Root Cause Was Different

Two consecutive Starship explosions occurring during the same flight phase, nearly within the same minute, and in similar ways, might suggest a common cause. However, that wasn’t the case.

Context. SpaceX recently provided details regarding the Starship’s explosive loss during its eighth test flight on March 6. Following the successful capture of the Super Heavy booster, all expectations hinged on the spacecraft, especially after its previous launch failed during the ascent phase.

The separation was successful. However, before reaching the altitude required to shut down the engines, SpaceX detected a flash near one of the spacecraft’s core engines. This was followed by an “energetic event” that caused that engine to disappear. Shortly after, two other center engines and one of the outer vacuum engines shut down, which resulted in the spacecraft losing control nine and a half minutes after liftoff. In the end, Starship 34 disintegrated over the Caribbean.

Not the vibrations. After two consecutive explosions, everyone assumed the problem was the same. On Flight 7, Starship 33 was lost eight minutes and 20 seconds after liftoff due to stronger-than-expected vibrations. These vibrations led to liquid oxygen leaks and a fire in an unpressurized area of the spacecraft known as the “attic section.”

However, the cause of the failure was different this time. “While the failure manifested at a similar point in the flight timeline as Starship’s seventh flight test, it is worth noting that the failures are distinctly different,” SpaceX points out in a press release. The company adds, “The mitigations put in place after Starship’s seventh flight test to address harmonic response and flammability of the ship’s attic section worked as designed prior to the failure on Flight 8.”

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Flight 8. SpaceX indicated that the likely cause of the spacecraft’s loss during the eighth flight was “a hardware failure in one of the upper stage’s center Raptor engines that resulted in inadvertent propellant mixing and ignition.”

In short, an engine component failed, causing a leak that mixed fuel (liquid methane) with oxidizer (liquid oxygen). The resulting explosion destroyed the engine and compromised the spacecraft’s survivability. Both issues originated in the lower section of Starship. However, the failure during Flight 7 occurred in the “attic,” whereas the failure during Flight 8 was in the “basement,” specifically the engine bay.

All set for Flight 9. To address the issues encountered during the previous flights, SpaceX has made several improvements to Starship 35. This includes reinforcements at key joints, a new nitrogen purge system, and enhancements to the propellant drainage system. In the future, the company plans to introduce the next-generation Raptor 3 engine, which will feature a complete redesign aimed at resolving similar issues.

If there are no further delays, the ninth flight will take off on Tuesday, May 27, at 6:30 p.m. local time at Starbase in Texas. This mission will be the first to reuse a Super Heavy booster–specifically Booster 14, which was used in the seventh mission. The spacecraft will also reattempt goals not completed during Flights 7 and 8, such as deploying eight Starlink satellite simulators and conducting multiple reentry experiments.

Image | Forest Katsch

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