SpaceX reveals the reason behind Falcon 9 second stage anomaly

On February 2, 2026, SpaceX launched a Falcon 9 rocket from Vandenberg Space Force Base in California. The mission carried 25 Starlink satellites into low-Earth orbit. The launch took place at 7:47 a.m. Pacific Time from SLC-4E. The first stage booster completed its 31st flight and landed successfully on the droneship Of Course I Still Love You in the Pacific Ocean.

The mission achieved successful payload deployment. However, the second stage encountered an issue later. After releasing the satellites, the second stage is designed to perform a deorbit burn. This burn ensures the stage reenters Earth’s atmosphere quickly and safely. In this case, the planned deorbit burn did not occur as expected.

SpaceX later identified the cause. A gas bubble formed in the transfer tube that supplies propellant to the engine. This bubble prevented proper ignition during the attempted burn. As a result, the second stage remained in orbit longer than planned.

The stage followed safety protocols. It passivated automatically, venting remaining propellants to reduce risks. About 10.5 hours after launch, the second stage reentered over the Southern Indian Ocean. No debris reached the surface, and no damage or sightings were reported.

SpaceX conducted a thorough review of the event. The company is now testing new pre-burn engine chill procedures. These changes aim to eliminate gas bubbles and improve ignition reliability for future deorbit burns. The goal is to ensure every Falcon 9 second stage completes its controlled reentry.

This work builds on ongoing improvements. In 2024, 13 out of 134 second stages remained in orbit after payload delivery. In 2025, that number dropped to 3 out of 165 launches. All stages that did not complete immediate deorbit were passivated and tracked. SpaceX coordinates with satellite operators to avoid any collision risks, while natural decay brings the stages down.

The anomaly did not affect the primary mission success. All 25 Starlink satellites reached their intended orbit and began operations. SpaceX continues to prioritize rapid and reliable deorbit of upper stages. These efforts support long-term sustainability in low-Earth orbit by reducing potential space debris.

The company applies lessons from this event across its fleet. Updated procedures will help maintain high reliability for both Starlink deployments and other customer missions. Falcon 9 remains one of the most active and proven launch vehicles in operation.

(source)