A persistent crack in the ISS is threatening its atmosphere

Space · Published 21 October 2026 Swipe more like this →

In short: Since 2019, a small but steady leak has been draining air from the International Space Station. Recently, the leak rate spiked, forcing astronauts to retreat into a safe haven as engineers weighed a high-risk repair strategy that could have compromised the station's structural integrity.

The issue is located within Russia's Zvezda service module, specifically in a component called the PrK transfer tunnel. The tunnel has suffered from cracks for several years, prompting a long-term collaborative monitoring and mitigation effort between NASA and Roscosmos. To manage the loss of atmosphere, Roscosmos has historically applied both temporary and permanent sealants to the affected area. The station's atmosphere has been slowly escaping since 2019. Both agencies have worked to determine the underlying cause of these fractures. The ongoing efforts focus on reducing the total volume of air lost. The goal remains maintaining the laboratory's pressurized environment.

During cargo operations involving the Progress 95 spacecraft in the first week of June 2026, the leak rate unexpectedly increased to approximately two pounds per day. This escalation led to the identification of new suspected leak locations. In response, Roscosmos proposed a more aggressive structural repair that involved cutting a bracket to gain better access to the interior. However, this specific method was flagged as potentially risky because it could have weakened the surrounding station structure. The leak rate rise was noticed during specific cargo maneuvers. Engineers identified multiple new areas of concern within the tunnel. The proposed fix was intended to provide better access to the interior. This plan was initiated on a Friday morning.

To ensure safety during the evaluation of this risky procedure, NASA directed the four SpaceX Crew-12 members and astronaut Chris Williams—who arrived via the Soyuz MS-28—to enter a 'safe haven.' They sheltered inside the SpaceX Dragon spacecraft while the plan was reviewed. Ultimately, NASA supported a decision to pause the structural work to gather more measurements and data. The crew was then able to return to normal operations as the teams continue to work with international partners to find a permanent resolution. The crew members were moved to the Dragon capsule as a precaution. This safety posture was maintained while the repair was being evaluated. The pause allowed for a review of previously applied sealants. NASA continues to coordinate with all international partners to resolve the matter.

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