A small section of the International Space Station that has experienced persistent leaks for years appears to have stopped venting atmosphere into space.

The leaks were caused by microscopic structural cracks inside the small PrK module on the Russian segment of the space station, which lies between a Progress spacecraft airlock and the Zvezda module. The problem has been a long-running worry for Russian and US operators of the station, especially after the rate of leakage doubled in 2024. This prompted NASA officials to label the leak as a “high likelihood” and “high consequence” risk.

However, recently two sources indicated that the leaks have stopped. And NASA has now confirmed this.

“Holding steady”

“Following additional inspections and sealing activities, the pressure in the transfer tunnel attached to the Zvezda Service Module of the International Space Station, known as the PrK, is holding steady in a stable configuration,” a space agency spokesman, Josh Finch, told Ars. “NASA and Roscosmos continue to monitor and investigate the previously observed cracks for any future changes that may occur.”

For the better part of half a decade, Russian cosmonauts have been searching for the small leaks like a proverbial needle in a haystack. They would periodically close the hatch leading to the PrK module and then, upon re-opening it, look for tiny accumulations of dust to indicate the leak sites.

Then the Russian cosmonauts would apply a sealant known as Germetall-1 (which has now been patented) to the cracks. They would close the hatch again, monitor the pressure inside the PrK module, and begin the search anew for additional leaks. This process went on for years.