SpaceX unexpectedly halted its second attempt to launch the revamped Starship rocket system on Thursday, mere moments after the booster ignited at the company’s facility in South Texas.

CEO Elon Musk stated on his social media platform X that “[s]ome of the engines didn’t ignite, causing an automatic launch abort” and announced that two of the engines would be replaced. According to him, SpaceX will not attempt another launch of Starship until next week.

SpaceX aimed to send its first third-generation Starlink satellites into orbit — although they are expected to disintegrate about 20 minutes after deployment, as Starship has not yet proven capable of reaching Earth orbit.

This is also SpaceX’s first Starship test launch since it went public on June 12, marking the largest IPO in history. The company secured over $85 billion in the deal and briefly approached the valuations of Amazon and Microsoft, although its stock has consistently declined throughout the past month.

On Thursday, SpaceX’s stock closed beneath its IPO price of $135, dropping over 4% in after-hours trading following the aborted launch.

SpaceX was attempting to resume launches shortly after the inaugural flight of Starship V3 in May, which was a mixed outcome.

Successfully departing the launchpad with the first version of a newly enhanced rocket was a significant advancement, and the company managed to deploy several Starlink simulators into space. However, the Super Heavy booster stage experienced a failure prior to its simulated landing attempt in the Gulf of Mexico, prompting an FAA-mandated review of the issues. (Earlier this week, the FAA authorized the company to launch Starship again after identifying several causes and remedies for the booster failure.)

During the May mission, Starship’s upper stage also lost an engine while deploying the Starlink simulators. Fortunately, the upper stage successfully executed its simulated water landing without any problems.

SpaceX was looking to make further progress on Thursday by launching the V3 Starlink satellites. The upgraded Starship and Starlink are essential to SpaceX’s ambitious plans to validate that the concept of “orbital data centers” is both technologically and economically feasible. Starlink is also the primary revenue source and the only profitable segment of SpaceX’s operations.

Thursday’s launch attempt appeared to be proceeding smoothly, with just a brief hold in the countdown at T-minus one minute before the planned launch. This hold cleared quickly, and the countdown resumed.

As the countdown reached zero, the launchpad’s water deluge system activated, and the booster stage visibly started firing its engines — only for everything to unexpectedly power down. Graphics from SpaceX’s broadcast indicated that four of the company’s new Raptor engines failed to ignite.

SpaceX must now remove all propellant from both the Super Heavy booster and the upper stage before determining what exactly failed on Thursday.

This story has been updated with new details from Elon Musk.