Seven-Year Zvezda Air Leak Elevates ISS Safety Risk

A hairline crack in the Zvezda module's PrK tunnel has vented breathable air into space since 2019, at times roughly 1.7 kilograms per day. NASA safety auditors have designated the PrK leak as the International Space Station's top open risk because a rapid failure could require a crew evacuation. Repairs and patches slowed the loss but did not stop it; the current workaround is to keep the hatch closed when not docking, containing the leak to the tunnel. NASA and Roscosmos remain at odds over cause and fixes, with options including permanently sealing the hatch or abandoning the aft docking port. The issue underscores aging ISS hulls and factors into the deorbit plan slated for 2030.