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A stubborn crack in the station's oldest Russian module is bleeding air into space, and engineers are running out of patches.
For a brief, hopeful moment earlier this year, it seemed the International Space Station had finally stopped hemorrhaging. After more than half a decade of chasing hairline cracks through one of its oldest Russian modules, NASA announced in January that the pressure inside the troublesome transfer tunnel had reached what engineers called a “stable configuration.” Translation: the leak, at last, appeared to be plugged.
The relief lasted about four months.
On May 1, while Russian cosmonauts were unloading supplies from the Progress 95 cargo ship, sensors picked up a familiar, dreaded signal — a slow, steady drop in pressure inside the small vestibule known as the PrK module, a narrow corridor that connects a docking port to the venerable Zvezda Service Module. The leak was back. Or, more accurately, it had never really left.
NASA confirmed the news this week, with agency spokesperson Josh Finch telling Ars Technica that data analysis indicated a loss of roughly one pound of air per day. Roscosmos, the Russian space agency, has since allowed the pressure in the tunnel to gradually decrease, monitoring the slide and topping it up with the occasional puff of nitrogen and oxygen.
“There are no impacts to station operations,” Finch said, “and NASA and Roscosmos are coordinating on next steps.”
That phrase — coordinating on next steps — has become something of a running theme aboard the world’s most expensive piece of real estate.
The story of the leak begins in September 2019, when cosmonauts first noticed that the station was losing air faster than it should. Inspections eventually revealed the cause: microscopic structural cracks, almost too small to see, threading through aging metal that has now spent nearly three decades baking, freezing, and dodging micrometeoroids in low Earth orbit.
For years, engineers tried sealant after sealant. The patches helped, but not enough. By 2024, the leak rate had doubled, from one pound a day to a little over two, and NASA quietly escalated the issue to the top of its internal risk matrix.
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Publicly, NASA has tended to downplay the danger. Internally, the tone is rather different. According to Ars Technica, in meetings, officials have used the words “catastrophic failure.”
Roscosmos, for its part, has managed the problem the old-fashioned way: by keeping the hatch to the leaky module sealed shut most of the time, essentially quarantining the offending section from the rest of the orbiting laboratory. It is the spaceflight equivalent of closing a door on a draft and hoping the house holds together until you can sell it.
The trouble is that the house may not be sold on schedule.
The ISS is officially due to retire in 2030, after which a SpaceX-built deorbit vehicle will guide its roughly 450-ton mass into a controlled plunge over an uninhabited stretch of the South Pacific. But NASA and the U.S. Congress are now openly weighing whether to push the date back to 2032, or possibly further, to avoid leaving a gap in America’s permanent human presence in orbit before private replacements are ready.
That extension would require buy-in from the station’s international partners, Russia included. And it would mean asking some of the oldest modules in space — pieces of hardware launched when The Phantom Menace was in theaters — to keep holding pressure for years longer than they were designed to.
A NASA safety advisory panel warned earlier this year that the station is entering what it called the riskiest period of its existence. The returning leak is precisely what the panel had in mind.
NASA’s plan for life after the ISS hinges on a handful of private companies — including Axiom Space, Vast, Voyager, and Blue Origin — building their own orbital outposts that the agency can rent space on, the way it now rents seats on SpaceX’s Dragon capsule. The transition has not gone smoothly. In March, NASA floated a revised plan at its Ignition event that would have commercial modules dock onto the ISS itself before going independent, an idea that landed with a thud among industry partners.
The companies say they will be ready by 2030. They worry that every extension of the ISS chips away at the market they have been promised. And they have a powerful argument on their side: the station is, quite literally, leaking.
“This further confirms the wisdom of the current policy of retiring the ISS in 2030 and replacing it with more modern, more cost-effective, and safer commercial platforms,” Phil McAlister, NASA’s former director of commercial spaceflight, told Ars Technica.
For now, the astronauts and cosmonauts aboard the station are safe and the leak is being managed pound by pound. But the message from that small, stubborn pressure drop is hard to mistake. The International Space Station, humanity’s greatest off-world construction project, is getting old. And the question is no longer whether it can be patched. The question is how gracefully it can be retired before the patches stop holding.
A space nerd and self-described grammar freak (all his Twitter posts are complete sentences), he loves learning about the unknown and figures that if he isn’t smart enough to send satellites to space, he can at least write about it. Twitter: @JordanS1981
© 2007-2025 ZME Science – Not exactly rocket science. All Rights Reserved.
© 2007-2025 ZME Science – Not exactly rocket science. All Rights Reserved.
