Ongoing air leaks in the Russian segment of the International Space Station (ISS) have intensified, forcing NASA and Roscosmos to navigate conflicting repair strategies. Recent efforts to seal cracks in the Zvezda module’s transfer tunnel—including a proposed plan to use a saw to access the area—led NASA to order five crew members to shelter in the docked SpaceX Dragon spacecraft on June 5, 2026. While the immediate threat was mitigated by pausing the repair, the agencies remain divided on the long-term structural sustainability of the orbiting laboratory.
Why is the ISS air leak escalating?
The leak originates from the PrK vestibule, a tunnel connecting the Zvezda module to a docking port, according to NASA. Initially reported in September 2019, the leak rate has climbed from one pound of air per day to two pounds, as reported by Roscosmos. The persistence of this issue for nearly seven years suggests that previous sealant applications have failed to fully stabilize the structural integrity of the aging Russian hardware.
The ISS uses a combination of high-pressure tanks and recycled oxygen to maintain cabin pressure. A loss of two pounds of air per day requires active management of the station’s atmosphere to ensure the safety of the crew.
What caused the recent safety intervention?
NASA ordered a “shelter-in-place” protocol for astronauts Jessica Meir, Jack Hathaway, Sophie Adenot, Andrey Fedyaev, and Chris Williams after Roscosmos proposed an aggressive repair plan. According to reports from Reuters, the Russian agency intended to use a saw to cut a bracket and gain better access to the leak site. NASA officials objected to this method, citing concerns that the mechanical intervention could pose an “elevated risk to the structure in the area,” according to a NASA update.
How do NASA and Roscosmos differ on safety?
The two space agencies hold diverging views on what constitutes an unsustainable risk level. A 2024 report from the NASA Office of Inspector General highlighted that these disagreements have become a recurring feature of ISS operations. While Roscosmos has maintained that the current leak rates do not threaten crew safety, NASA’s cautious approach during the June 5 incident reflects a lower tolerance for structural modification risks. This tension underscores the difficulty of managing a multi-national facility where maintenance procedures are subject to different engineering standards.
Pro Tip: Monitoring Structural Health
When dealing with pressurized environments in orbit, “less is more.” Engineers often prefer non-invasive monitoring over mechanical cutting, as every modification introduces new stress points on the hull. Future missions will likely prioritize sensor data and remote inspection before attempting high-risk, physical repairs.
What happens next for the Zvezda module?
Roscosmos has paused current repair efforts to conduct additional data assessments and inspections of suspected crack sites. The agency noted that one of two identified cracks may have been successfully sealed, though this remains subject to verification through upcoming pressure measurements. Should the leaks continue to worsen, both agencies may eventually be forced to permanently isolate the Zvezda service module by closing the hatch, effectively shrinking the habitable volume of the ISS to preserve the atmospheric integrity of the rest of the station.
Frequently Asked Questions
- Is the ISS currently unsafe for the crew? NASA and Roscosmos have not declared the station unsafe, but NASA implemented temporary safety protocols during recent repair attempts to minimize risk.
- Why can’t they just fix the leak permanently? The leak is located in an area that is difficult to access, and the two agencies have yet to agree on a repair method that does not risk further structural damage.
- What is the “shelter-in-place” protocol? It is a safety measure where crew members move to their return vehicles—in this case, the SpaceX Dragon—to ensure they can depart the station immediately if a sudden loss of pressure occurs.
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