NASA indefinitely delays private astronaut mission, citing air leak in Russian module

WASHINGTON — NASA and Axiom Space are indefinitely delaying a private astronaut mission to the International Space Station after detecting a “new pressure signature” in a part of the station that has had a long-running air leak.

NASA said June 12 that the agency, along with Axiom Space, has agreed to delay the Ax-4 private astronaut mission to the ISS. They did not announce a new launch date for the mission.

The delay, NASA said, would give NASA and Roscosmos more time to study a new development with an air leak in a compartment of the Zvezda module. That leak was first detected in 2019 and Roscosmos has been working for years to try to fix.

“As part of an ongoing investigation, NASA is working with Roscosmos to understand a new pressure signature, after the recent post-repair effort in the aft most segment of the International Space Station’s Zvezda service module,” NASA stated. The agency did not elaborate on the nature of that pressure signal in the statement, deferring questions to Roscosmos. That agency has not commented on the leaks, although June 12 was a national holiday in Russia.

NASA said that cosmonauts had performed inspections of the module and sealed “additional areas of interest,” adding that the module is holding pressure. “The postponement of Axiom Mission 4 provides additional time for NASA and Roscosmos to evaluate the situation and determine whether any additional troubleshooting is necessary,” NASA stated.

Leaks in that part of the Zvezda module, a vestibule called PrK that links a docking port to the rest of the module, has been a concern for years, with different levels of concern between NASA and Roscosmos. Last November, a NASA ISS advisory panel noted that NASA and Roscosmos don’t have a shared understanding of the cause of the leaks or their severity, with NASA particularly concerned about a “catastrophic failure” of the vestibule.

The vestibule is sealed off from the rest of the station when crews don’t need to access Progress cargo spacecraft when docked there. When the vestibule is opened, NASA astronauts have taken steps such as closing the hatch between the American and Russian segments of the station.

The issues with PrK have also alarmed NASA’s Aerospace Safety Advisory Panel. At an April 17 meeting of the panel, one member, Rich Williams, called the leaks in that vestibule “one of our highest concerns.”

The NASA announcement came as SpaceX appeared to be ready to launch the Ax-4 mission after delaying a June 11 launch attempt because of a liquid oxygen leak. The company performed a tanking test on the pad June 12, after NASA announced the indefinite delay in the mission. SpaceX said in a social media post that it would “work closely” with NASA and Axiom Space to find a new launch opportunity for the mission.

“This is the right thing to do for Axiom Space, for NASA, and for our customers. We will continue to work with all of our partners to finalize a new launch date and look forward to flying the Ax-4 Mission soon,” Kam Ghaffarian, executive chairman of Axiom Space, said in a post.

NASA said at a June 9 briefing that there would be launch opportunities for Ax-4 through the end of June and again starting in the second week of July. A significant delay, though, could affect the schedule for the Crew-11 mission, scheduled for launch no earlier than late July.