A leak in the International Space Station is getting worse – and keeping NASA awake at night

U.S. space officials don’t like to talk about the dangers of flying astronauts on the aging International Space Station, parts of which are now more than a quarter century old.

But a new report confirms that NASA managers responsible for space station operations are seriously concerned that a small Russian portion of the station, essentially a tunnel connecting a larger module to a docking port, is leaking.

Russian and US officials know that this small PrK module, located between an airlock on the Progress spacecraft and the Zvezda Module has been leaking since September 2019. A new report released Thursday by NASA’s inspector general contains details the space agency had not previously released, underscoring the severity of the problem.

New details about the leak

For example, in February of this year, NASA noted an increase in the leak rate from less than 1 pound of atmosphere per day to 2.4 pounds per day, and in April this rate increased to 3.7 pounds per day. Despite years of investigation, neither Russian nor US officials have identified the underlying cause of the leak.

“Although the root cause of the leak remains unknown, both agencies have limited their focus to internal and external welds,” said the report, signed by Deputy Inspector General George A. Scott.

The plan to mitigate the risk is to leave the hatch on Zvezda PrK tunnel module closed. If the leak continues to worsen, this hatch may need to be closed permanently, reducing the number of Russian docking ports on the space station from four to three.

Publicly, NASA has tried to minimize concern about the crack problem, as to date it has been limited to the PrK tunnel and has not spread to other parts of the station. Still, Ars reported in June that the cracking problem had reached the highest level of concern in the space agency’s 5×5 “risk matrix” for classifying the likelihood and consequences of risks to space activities. The Russian leaks are now rated “5” for both high probability and high impact.

At this time, NASA would not comment or confirm the space agency’s concerns about the risk matrix assessment. However, the new report confirms the agency’s concerns.

“In May and June 2024, representatives from the ISS program and Roscosmos met to discuss increasing concerns about the increased leak rate,” the inspector general’s report said. “The ISS program subsequently raised the leak risk in the service module transfer tunnel to the highest risk level in its risk management system. According to NASA, Roscosmos is confident that they will be able to monitor and close the hatch to the service module before the leak. “The leak rate is reaching unsustainable levels. However, NASA and Roscosmos have not reached agreement on the point at which the leak rate becomes unsustainable.

An uncertain future in low Earth orbit

The report comes as NASA considers the future of the space station. The US space agency and Russia have an agreement to continue operating the station until 2028, and NASA would like to extend operations until 2030. NASA had already expected to agree to this extension more than a year ago, but has not yet finalized an agreement.

Once the station reaches the end of its life, NASA intends to shift its low-Earth orbit activities to private space stations and has funded initial development work by Axiom Space, Northrop Grumman, Blue Origin and Voyager Space. Northrop has since withdrawn from competition, concluding that it will not be a profitable company. There is general uncertainty about whether any of the private space station operators will be ready in 2030.

NASA’s other possible option is to extend the space station’s lifespan beyond 2030. However, this would require a lot of work to ensure that the space station structure remains viable, and yet another extension agreement with Russia. The US partnership with this country has been severely strained by the Russian invasion of Ukraine.

“An expansion of the ISS beyond 2030 requires significant funding for station operations and maintenance, acceptance of the increased risk posed by its components and aging structures, and assurances of continued support from NASA’s international partners,” says the new report. “To make matters worse, NASA may continue to face a flat or reduced budget, inflation and supply chain challenges.”

This story originally appeared on Ars Technica.