WASHINGTON — NASA and Roscosmos continue to disagree over the cause and severity of an air leak in the Russian segment of the International Space Station, a leak that NASA says could lead to a ” catastrophic failure” of part of a Russian module.

This disagreement was highlighted during a brief meeting of NASA’s ISS advisory committee on November 13, which recounted a meeting of that committee with its Roscosmos counterpart in Moscow in September to discuss problems with the station.

The major problem has been a small but persistent leak in a vestibule of the Zvezda service module called PrK that separates a docking port from the rest of the module. This leak has existed for several years and station crews have resolved the leak by isolating PrK from the rest of the station when they do not need access to the Progress cargo spacecraft docked at the port.

“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 ” said Bob. Cabana, a former NASA astronaut and associate administrator who now chairs the committee.

He said Russian engineers believed the cracks were likely caused by “high cyclic fatigue” from micro-vibrations. NASA, on the other hand, believes that several factors come into play, including mechanical pressure and stress, residual stress, module material properties, and environmental exposure.

In September, a report from NASA’s Office of Inspector General (OIG) stated that “both agencies focused on internal and external welds” as the cause of the leaks, which were not observed elsewhere on the station. .

During a briefing on September 27, NASA officials downplayed concerns about leakswhich were first detected in 2019 but earlier this year reached their highest rates ever, a loss of 1.7 kilograms of air per day, the OIG report said. At that meeting, agency officials said recent repair work had reduced the leak rate by a third.

The leaks, however, remain a source of concern for agencies as well as the space station crews. At a Nov. 8 briefing, Michael Barratt, a NASA astronaut who returned to Earth in October on the Crew-8 mission after nearly eight months on the station, said his Russian counterparts had been ” very open” on the issue, but that NASA took the time to do so. precautions when the PrK hatch is open.

“We took a very conservative approach to closing the gap between the American side and the Russian side during these times,” he said. “It’s not a comfortable thing, but it’s the best deal between all the smart people on both sides, and it’s something we as a crew live with.”

Cabana said at the committee meeting that there was also no agreement between NASA and Roscosmos on the severity of the problem. “Even as the Russian team continues to research and plug leaks, they do not believe that a catastrophic disintegration of PrK is realistic,” he said. “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 concluded.

Cabana said the NASA and Roscosmos committee jointly recommended their agency leaders continue to seek a “common understanding of the structural integrity” of PrK and bring in outside experts from academia and the industry to support these efforts.

He offered no timetable for those efforts, but said NASA had brought in an independent team to evaluate the leaks. “This is an engineering problem and good engineers should be able to find and agree on a solution.”

“The station is not young. He’s been up there for quite a while. You expect some wear and tear, and we see that,” Barratt said during the Crew-8 briefing.

The PrK flight was the main topic of the meeting, which lasted only about ten minutes, although the Federal Register Notice because the planned meeting would last an hour. This was the committee’s first public meeting since March 2020, when the committee was chaired by former astronaut Tom Stafford, who died last March.

Related