The Axiom-4 mission, which will carry Indian payload specialist Shubhanshu Shukla, was delayed yet again due to a propellant leak in the Falcon 9 rocket. SpaceX, the company behind the mission, also confirmed that a liquid oxygen (LOx) leak was detected in post-static fire testing, which tests the rocket while it’s still attached to the launch pad. Initially targeted for May 29, the mission has faced successive delays, the latest pushing the launch further from its recent 11 June schedule. ISRO scientists have mentioned the issue may delay liftoff by “another few days” depending on repair progress and safety validations.

LOx Leak in Falcon 9 Forces Fourth Delay of Axiom-4 Mission with India’s Shubhanshu Shukla

As per a statement from SpaceX, the LOx leak was identified after the static fire booster test, prompting the team to stand down from the latest launch window. According to The Print, ISRO officials said that an LOx issue this close to launch generally requires the rocket to be pulled back for thorough inspection. However, the ISRO team, unfamiliar with SpaceX’s proprietary systems, refrained from commenting on specific technical procedures, the publication said. The first signs of the leak were reportedly detected on 8 June.

Falcon 9’s Merlin engines rely on LOx (liquid oxygen), along with RP-1 (rocket-grade kerosene), as an oxidiser to propel the vehicle. During static fire tests, the engines are briefly ignited to validate their performance. Detection systems, including oxygen sensors and thermal imaging, help identify leaks in these stages. The Ax-4 mission had already been rescheduled multiple times — initially from 29 May to 8 June, then to 10 June, and again to 11 June — due to weather concerns.

SpaceX vice president Bill Gerstenmaier told reporters during a pre-launch briefing that a solution was underway. “We’re putting in a purge that will stop the leak,” he mentioned, adding that the problem was under control. Still, the ultimate launch date is up in the air and will rely on the results of continuing safety assessments.

Axiom Space is in charge of the project, a major step for India’s human spaceflight program. It features Shubhanshu Shukla as part of a commercial crew going to the International Space Station. Technical problems are common in space operations, but this fourth delay shows how hard it is to make sure that everything is perfect for crewed missions to take off.