Full Breakdown
ISS Russian Module Leak Prompts Decommissioning Plan
6/18/2026, 11:47:44 AM
Ongoing Air Leak in the Russian PrK Vestibule
In September 2019 Roscosmos reported a slow air leak in the PrK vestibule, a tunnel linking a docking port to the Zvezda service module of International Space Station. The leak persisted for seven years despite multiple sealing attempts by Russian cosmonauts. A 2024 assessment showed the loss rate rose from about one pound per day to just over two pounds per day, prompting NASA to label the issue highest-level risk.
Chronology of the Leak and Repair Attempts
Key milestones: the leak report in September 2019; a pressure drop on May 1 during Progress 95 cargo unloading; NASA’s June 5 order for the crew to shelter in the SpaceX Dragon capsule as Russia readied a saw-cut repair of a load-bearing bracket; a June 2025 pressure signal suggesting a possible seal improvement; and later in 2025 Roscosmos postponing the saw operation and announcing plans to decommission the PrK vestibule by closing its hatch.
Leak Rate and Monitoring Data
The loss rate rose from about one pound per day in 2019 to just over two pounds per day by 2024. Pressure sensors on May 1 recorded a gradual drop in Zvezda, confirming ongoing loss. The June 2025 pressure signal was interpreted as a potential improvement, though no definitive post-repair measurements have been released.
Official Positions of NASA and Roscosmos
NASA publicly rejected the saw-cut repair, stating that it could increase structural risk. NASA also cited the need to shelter the crew in the Dragon capsule. Roscosmos announced its intent to decommission the PrK vestibule, describing hatch closure as a way to isolate the leak and limit air loss. The agency said the move will force Russian cosmonauts to use alternative docking ports for future supplies.
Critique of the Saw-Cut Repair Plan
NASA’s risk analysis emphasized that cutting a load-bearing bracket could compromise structural integrity and increase the chance of damage to adjacent components. The agency argued that the potential hazards outweighed any expected benefit, leading to the postponement of the operation.
Conflicting Assessments and Unresolved Issues
NASA’s June 2025 pressure-signal detection suggested a possible seal improvement, yet Roscosmos proceeded with decommissioning, showing a lack of consensus on the leak’s status. The exact cause of the crack remains undisclosed, and no post-repair data have been published.
Verbatim Quote
“could have resulted in elevated risk to the structure in the area.” — NASA official
Future Outlook for the ISS Russian Segment
If Roscosmos closes the PrK hatch, the vestibule will be isolated, ending the air-loss episode but eliminating a Russian docking pathway. Future cargo transfers will use other ports on Zvezda or other ISS modules. Ongoing monitoring will verify the sealed section’s stability and guide further safety measures.
