ISS Crew Shelters in Dragon Capsule Amid Tense Standoff Over Risky Russian Module Repairs

ISS Crew Shelters in Dragon Capsule Amid Tense Standoff Over Risky Russian Module Repairs

On June 5, 2026, the International Space Station (ISS) was the site of a tense operational standoff and safety alert. NASA ordered the four members of its Crew-12 mission and NASA astronaut Chris Williams to assume an elevated safety posture and shelter inside the SpaceX Crew Dragon capsule.

The emergency shelter order was triggered by a unilateral decision by the Russian space agency, Roscosmos, to proceed with an extensive and highly controversial structural repair of a persistent air leak in the Russian-built Zvezda service module's PrK transfer tunnel.

The PrK tunnel, a narrow vestibule connecting a docking port to the rest of the Zvezda module, has been leaking air through hairline cracks since September 2019, venting nearly 2 kilograms of air per day. NASA's safety auditors have flagged the cracks as the single highest open risk aboard the entire station.

The June 5 incident escalated when:

• Roscosmos flight controllers detected an increase in the leak rate and elected to proceed with aggressive, structural repair operations.
• According to reports from NASA officials, Roscosmos proposed using high-risk mechanical methods, including drilling and sawing into the module's hull to seal the cracks.
• NASA strenuously objected to this approach, fearing it could catastrophically compromise the structural integrity of the aging module.
• Out of an abundance of caution, NASA ordered its astronauts to evacuate the U.S. segment and shelter in the Crew Dragon spacecraft, while closing the hatch between the U.S. and Russian segments of the station.

The standoff was defused after less than two hours when Roscosmos agreed to call off the aggressive repairs. Instead, Russian cosmonauts Sergey Kud-Sverchkov and Sergei Mikaev took measurements and applied a temporary sealant over one of the potential leak sites.

The incident highlights a deep, ongoing disagreement between NASA and Roscosmos over the root cause and severity of the Zvezda cracks. While Roscosmos has suggested permanently sealing off the PrK tunnel if repairs fail¹, doing so would permanently eliminate a key cargo docking port and severely limit the station's operational flexibility. NASA faces a 2027 technical deadline to decide whether the tunnel must be permanently closed.