Air Leak in Russian ISS Module Stabilized After Repairs, NASA Confirms.

Bill Spetch, NASA’s ISS Operations Integration Manager, confirmed that the air leak in the PrK transfer tunnel—linking the Zvezda service module with docking ports for Russian cargo vehicles—has shown “steady” pressure levels since the repair operations. While NASA withheld specifics about the exact repairs conducted, Spetch said the leak rate is now so low it's difficult to quantify, describing it as “pretty steady, pretty small.”

The leak, while not posing an immediate danger, had nonetheless raised concerns due to its persistence over several years and a notable increase earlier this year—from one pound of air per day to two in February. Though the tunnel can be sealed off with hatches when not in use, NASA and Roscosmos took a cautious approach due to the interdependence of their ISS modules.

The situation prompted a nearly two-week delay for the Axiom-4 (Ax-4) private astronaut mission, originally scheduled for June 10. Though initial setbacks were due to weather and a liquid oxygen leak on SpaceX’s Falcon 9 rocket, the final delay to June 25 came at NASA’s request to verify the effectiveness of the Russian repairs.

“There was a leak signature difference we wanted to evaluate,” Spetch explained. “Roscosmos performed troubleshooting on the hatch, and we had to examine multiple pressure levels to confirm that the leak was resolved.”

Ax-4’s four-person international crew remained in quarantine throughout the extended delay and is currently aboard the ISS. Their return to Earth is targeted for Monday, July 14.

Despite prior disagreement between NASA and Roscosmos over the source and risk of the leak, both agencies are now working closely—alongside external experts—to investigate root causes and share data through a standing joint commission.

Spetch also confirmed that aside from the now-stabilized PrK tunnel, “the rest of the station is leak tight.”

Boeing’s Starliner Faces Uncertain Next Step

The briefing also addressed Boeing’s Starliner spacecraft, which flew its first crewed mission earlier this year. That flight faced challenges, particularly with Starliner’s propulsion system, leading to a decision to return the capsule empty. The two astronauts—NASA’s Butch Wilmore and Suni Williams—have remained on the ISS longer than planned and will return aboard SpaceX’s Crew Dragon.

NASA and Boeing are still evaluating how best to proceed with Starliner’s next mission. While a decision has not been finalized, there is a strong possibility that Starliner’s next flight will carry only cargo to validate recent technical changes.

“We’re weighing whether it’s better to validate the propulsion changes in an uncrewed flight,” said Steve Stich, NASA Commercial Crew Program Manager. “There’s a strong chance we’ll fly a cargo flight first, but that decision is still ahead of us.”

NASA originally envisioned Starliner as a key element in a dual-provider system—known as “dissimilar redundancy”—to ensure continuous crew access to the ISS. While SpaceX’s Crew Dragon has been operational since 2020, Starliner remains in its testing phase.

Meanwhile, Crew-11 is scheduled to launch no earlier than July 31, carrying four astronauts: two from NASA, one from Japan’s JAXA, and one from Roscosmos. NASA is also reconsidering mission lengths and capsule reuse certifications amid budget pressures.

While Crew Dragon is currently certified for missions of up to 210 days, NASA and SpaceX are working to extend that to 8 months. Crew-11 is expected to stay for 6 months but could remain longer if certification efforts succeed.

Additionally, NASA and SpaceX aim to expand the reuse certification of Crew Dragon capsules from five to 15 missions. Sarah Walker, SpaceX’s Director of Dragon Mission Management, said about 70% of spacecraft components are already certified for the extended use, while work continues on the rest.

By Azhar