Over the past five years, air has been leaking at an increasing rate through a Russian section of the International Space Station (ISS). NASA and its Russian counterpart, Roscosmos, are still at odds over the root cause of the leak, as well as the severity of the consequences.

The leak was first discovered in 2019 in the vestibule (named PrK) that connects a docking port to the Russian Zvezda module, which Roscosmos launched into low Earth orbit in July 2000. Earlier this year, NASA elevated the leak to the highest level of detection. risk because the air flow escaping from the module had doubled, from one pound of air per day to just over two pounds.

“Although the Russian team continues to search for and plug leaks, they do not believe that catastrophic disintegration of PrK is realistic,” said Bob Cabana, a former NASA astronaut who now chairs the PrK advisory committee. ‘ISS, during a meeting Wednesday, SpaceNews. reported. “NASA has expressed concerns about the structural integrity of the PrK and the possibility of catastrophic failure.”

“The Russians believe that continued operations are safe, but they cannot prove to our satisfaction that they are safe, and the United States believes that it is not safe, but we cannot prove to our satisfaction Russians that this is the case,” he added.

Russian teams believe the air leak was likely caused by high cyclic fatigue from micro-vibrations, while NASA teams believe mechanical pressure and stress, residual stress, material properties of the module and environmental exposure are all at stake, according to SpaceNews.

The air leak was discussed in a recent report by NASA’s Office of Inspector General (OIG), which highlighted its true severity and the risk it poses to the crew. The OIG report states that the two space agencies cannot seem to agree on the point at which the leak should be considered unsustainable. NASA and Roscosmos met to discuss the ISS air leak, with NASA officials noting that Roscosmos “is confident that they will be able to monitor and close the service module hatch before the leak rate reaches an unsustainable level,” according to the report.

“Although the teams continue to study the causal factors for the appearance and growth of the cracks, the U.S. and Russian technical teams do not have a common understanding of the likely root cause or the severity of the consequences of these leaks “, explains Cabana. quoted in SpaceNews as saying.

The air leak rate from the hole increased about a week before the Feb. 14 launch of the Progress MS-26 cargo spacecraft, which docked at Zvezda’s rear end. The hatch that connects the module to the ISS remained open for five days while the crew unloaded Progress MS-26’s cargo onto the space station, but was then closed again.

NASA and Roscosmos are currently monitoring the leak and preparing to close the service module hatch when access is not required in order to minimize the amount of air lost and to isolate the leak itself from the rest of the space station. If necessary, space agencies are ready to permanently close the hatch if the leak rate becomes unmanageable. The ISS would operate normally, but there would be one less docking port for spacecraft delivering cargo to the space station.

As the two space agencies continue to discuss potential risks, the aging space station is moving closer to retirement within six years and its hardware may finally give way to the wear and tear of the hostile space environment.