WASHINGTON — SpaceX is suspending launches of its Falcon 9 rocket after a problem with the deorbit burn of the upper stage on a crewed launch Sept. 28, the second upper stage anomaly in less than three months for the rocket.
SpaceX said in a social media post early Sept. 29 that the upper stage “experienced an off-nominal deorbit burn” during the Crew-9 mission that launched Sept. 28. “As a result, the second stage safely landed in the ocean, but outside of the targeted area.”
The company did not provide additional details on the incident but said that it would halt Falcon 9 launches for the time being. “We will resume launching after we better understand root cause.”
The burn is designed to target the reentry of the upper stage, disposing of the stage over an unpopulated region of the South Pacific Ocean to both avoid leaving the stage in orbit, where it would pose an orbital debris risk, and to prevent an uncontrolled reentry. The targeted reentry location, based on airspace and marine hazard notices, was east of New Zealand.
The incident is the second problem involving the upper stage of the Falcon 9 in less than three months. On a Starlink launch late July 11, the single Merlin engine in the upper stage malfunctioned when reigniting on a second burn to circularlize its orbit. The satellites were deployed, but in low orbits that resulted in the satellites soon reentering.
An investigation concluded that the engine suffered a liquid oxygen leak created by a crack in a sense line for a pressure sensor. The leak resulted in “excessive cooling of engine components” including those that deliver ignition fluid to the engine. That caused the engine to suffer a hard start when it reignited, damaging the engine and causing a loss of attitude control.
On that July launch, the liquid oxygen leak was seen in video of the first burn of the upper stage as ice built up on engine components. There was no sign of similar ice buildup or other anomalous behavior of the stage during the Crew-9 launch, and neither SpaceX nor NASA mentioned any issues with the rocket during a post-launch press conference.
It is unclear how long SpaceX would pause Falcon 9 launches. The July incident halted Falcon 9 launches for 15 days, with the rocket returning to flight early July 27. SpaceX also halted launches for two days in late August after a booster was lost when it tipped over and exploded upon landing on a droneship in the Atlantic Ocean.
In both earlier cases, SpaceX needed approval from the Federal Aviation Administration to resume launches either after completing a mishap investigation or receiving a public safety determination from the agency that the incident did not pose any risk to the general public. The FAA did not immediately respond to questions on the incident early Sept. 29.
The anomaly comes as SpaceX is preparing for two time-sensitive launches in the coming weeks. One Falcon 9 is scheduled to launch as soon as Oct. 7 carrying the European Space Agency’s Hera asteroid mission. A Falcon Heavy, whose upper stage is similar to the Falcon 9, is scheduled to launch NASA’s Europa Clipper spacecraft no earlier than Oct. 10. Both missions have launch windows that run through late October.
