June 11, 2025 at 10:55 AM EDT SpaceX called off a planned Wednesday morning launch attempt of the crewed Axiom Space Ax-4 mission to deal with a liquid oxygen leak on the rocket booster. “Standing down from tomorrow’s Falcon 9 launch of Ax-4 to the @Space_Station to allow additional time for SpaceX teams to repair the LOx leak identified during post static fire booster inspections,” SpaceX posted on X late Tuesday. “Once complete – and pending Range availability – we will share a new launch date.” The Ax-4 mission was aiming for an 8 a.m. liftoff with weather concerns looking to potentially delay the flight, but in the end hardware issues made those moot. Now forced to wait are Axiom Space employee and former NASA astronaut Peggy Whitson commanding a crew of customers paid for by the governments of India and Hungary as well as Poland through the European Space Agency. “Human spaceflight’s really core to SpaceX’s ultimate mission and flying crew safely is always our top priority,” said SpaceX’s William Gerstenmaier, vice president of Build and Flight Reliability, during a Monday press call when he first discussed finding the leak. “Spaceflight is really hard, and we’re learning every day. The more we fly, the more we learn.” He said SpaceX had first detected the leak during the booster’s previous flight, which was its debut launch in late April. “We had not fully repaired the booster during refurbishment, or we didn’t, actually, didn’t find the leak and didn’t get it corrected,” he said. At the time, he was confident SpaceX would have the rocket ready for the Wednesday attempt. “We’ve gone out to the launch pad. We’re continuing to troubleshoot that. We should get that completed (Monday) and we will have that back in configuration,” he said. “We’re installing a purge that will essentially mitigate the leak if it still continues, if we see it on launch day. So we will be fully ready to go fly.” In the end, SpaceX opted to hold off what would have been its third human spaceflight mission of the year following the March launches of the Crew-10 mission to the space station and the polar orbital mission Fram2. “I think this shows the difficulty of getting ready. You can always be prepared, but doing the testing, doing the dry runs, doing the activities with the crew to make sure we are really ready, is tremendously important because we always learn something,” he said. Dana Weigel, NASA’s International Space Station program manager, said any delay this week should not pose too much of an issue. “We have launch opportunities all the way through June 30,” she said, and then a break until about the second week in July. “So plenty of opportunities to fly to these people.” The mission aims to dock with the station the day after launch and then spend about two weeks on board before returning for splashdown off the California coast. It would be the fourth trip for Axiom Space to the station and second for Whitson for the company. Ax-4 would be her fifth trip to space overall and she would add to the more than 675 days in space she’s already experienced in her career. That’s the most for any American as well as the most for any woman in history. The three customers are India’s Shubhanshu Shukla, taking the role of pilot, while Hungary’s Tibor Kapu and Poland’s Sławosz Uznański-Wiśniewski are mission specialists. None of those countries have had astronauts fly to space in more than four decades. The Indian Space Research Organization said it pushed hard for the hardware fixes to be tackled to ensure the astronauts’ safety. “Based on the discussion on this topic by ISRO team with the experts of Axiom and SpaceX it has been decided to correct the leak and carry out necessary validation test before clearing for the launch,” V. Narayanan, chairman of ISRO, said in a post on X. Originally Published: