Russia to Permanently Close Leaking ISS Tunnel
The PrK tunnel will be isolated from the Russian Zvezda module to stop a persistent air leak that peaked in 2024.
Updated on Oct. 27, 2026 in Space
Live Poll
Should nations prioritize maintaining aging international space stations despite persistent technical challenges?
Roscosmos plans to permanently seal the PrK transfer tunnel on the International Space Station following years of persistent air leaks. The closure will shift future cargo operations for spacecraft like the upcoming Progress MS-36 to the station's Poisk module.
Why it matters
Permanently sealing a section of the station marks a significant mitigation step for a long-term structural issue that has persisted since 2019. By isolating the PrK tunnel from the Zvezda module, mission managers aim to eliminate a leak path that reached an peak loss of 3.7 pounds of air per day.
The PrK transfer tunnel recorded a peak daily air leak rate of 3.7 pounds in April 2024. While NASA sensors indicated a potential temporary seal in June 2025, the persistent nature of the pressure drops has prompted the decision to isolate the tunnel entirely.
The players
Roscosmos
The Russian state space corporation responsible for the operation and maintenance of the Russian segment of the International Space Station.
NASA
The United States government agency responsible for civil spaceflight and international cooperation on the International Space Station.
The details
The PrK tunnel acts as a pressurized transition segment connecting a docking port to the Russian Zvezda module. To address the leaks, Roscosmos will seal the hatch between the module and the tunnel, effectively removing the segment from the active pressurized volume of the station. This change requires shifting the unloading process for resupply ships, such as the Progress MS-36, to the Poisk module, which features an independent docking interface.
Timeline
2019: First air leak detected in the PrK transfer tunnel.
April 2024: Leak rate peaked at 3.7 pounds per day.
June 2025: NASA measured a pressure signal suggesting the leak was temporarily sealed.
November 2026: Russia is scheduled to launch the Progress MS-36 cargo spacecraft.
The Tech Race
The closure follows years of attempts to locate and repair the breach, which has been monitored since the 2019 International Space Station air leak detection. This decision signals a shift toward containment over further intrusive repairs, such as the saw-based access method proposed by Russian engineers.
This hardware isolation will not affect the daily operations of most station research experiments, but it forces a permanent change in logistics for the Russian segment. Ground crews and cosmonauts must now route all future cargo transfers through the Poisk module.
The takeaway
The permanent sealing of the PrK tunnel represents a move to prioritize station pressure integrity over access to a compromised segment. Observers should track the arrival of the Progress MS-36 to see if the logistics shift to the Poisk module proceeds without further structural complications.
What happens next
Russia is scheduled to launch the Progress MS-36 cargo spacecraft in November 2026, which will be the first major logistics mission to utilize the Poisk module for unloading.
Further reading
For more on the challenges of maintaining aging orbital infrastructure, visit Space.
Source note: This article includes information reported by Gizmodo.
Live Poll
Should nations prioritize maintaining aging international space stations despite persistent technical challenges?
