The ISS is leaking air – and NASA and Russia can’t agree on why

In the last five years, air has been escaping through a Russian section of the International Space Station (ISS) at an increasing rate. NASA and its Russian counterpart, Roscosmos, still disagree about the cause of the leak, as well as the severity of the consequences.

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

“While the Russian team continues to search for and seal the leaks, it does not believe that catastrophic disintegration of PrK is realistic,” Bob Cabana, a former NASA astronaut who now chairs the ISS advisory board, said during a meeting Wednesday, SpaceNews reported. “NASA has expressed concern about PrK’s structural integrity and the possibility of a catastrophic failure.”

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

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

The air leak was addressed in a recent report by NASA’s Office of Inspector General (OIG), which highlighted its true seriousness and the risk it posed to the crew. The OIG report stated that the two space agencies cannot 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 investigate the causative factors of the fissure initiation and growth, the US and Russian engineering teams do not have a common understanding of what the likely root cause is or the severity of the consequences of these leaks,” says Cabana. quoted in SpaceNews as saying.

The rate of air leakage from the hole increased about a week before the February 14 launch of the Progress MS-26 cargo spacecraft, which docked at the rear of Zvezda. The limb connecting the module to the ISS remained open for five days as the crew unloaded the cargo from Progress MS-26 to the space station, but was closed afterwards.

NASA and Roscosmos are currently monitoring the leak and preparing to close the service module hatch when access is not required to minimize the amount of air lost and isolate the leak itself from the rest of the space station. If necessary, the space organizations are prepared to permanently close the hatch if the leakage 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 the potential risk, the aging space station is approaching retirement within the next six years, and its hardware may finally succumb to the wear and tear of the harsh space environment.