WASHINGTON — A Russian module on the International Space Station continues to suffer an air leak after hopes that recent repairs had resolved the long-running problem.
At a July 30 press conference about the launch of the Crew-11 mission to the ISS, scheduled for 12:09 p.m. Eastern July 31, a senior Roscosmos official said a leak persisted in a portion of the Zvezda service module even after recent repairs.
“The leak still continues. We keep searching for the leak and repair the leak,” said Sergei Krikalev, deputy director general of manned and automated complexes at Roscosmos and a veteran former cosmonaut. “Recent repairs actually reduced the leak rate significantly. For a period of time, we were even thinking that we finally found the last crack and repaired it.”
That is a reference to recent work in a vestibule of Zvezda, known as PrK, that connects a docking port to the rest of the module. That work resulted in what NASA called a “new pressure signature” in the vestibule that prompted NASA to delay in June the launch of a private astronaut mission to the station to investigate it.
NASA later said that new pressure signature was pressure holding steady in PrK rather than dropping as previously seen. That could indicate the leak had sealed, although NASA said at the time it could also mean air leaking through a seal in a hatch sealing off PrK from the rest of the station.
At a July 10 briefing about the Crew-10 mission, Bill Spetch, operations integration manager for the ISS program at NASA, said that there was a “very small” leak rate now in PrK, but didn’t quantify it.
“Over a long period of time, the leak still continues, but it reduced significantly,” Krikalev said, later calling that most recent repair “very successful.”
The leak rate, he said, depends on several factors, such as the pressure in PrK. That vestibule, usually sealed off from the rest of the station, is kept at a lower pressure, which reduces the leak rate.
Krikalev said that Roscosmos continues to work with NASA to study the air leak in PrK, which has persisted for several years and become a cause for concern for NASA. He said experts at both agencies are studying topics like crack propagation and corrosion.
“All these scientists are working together to find the root cause of these cracks,” he said. “It’s important for all, for the future designs of future stations, to be sure that we will not have a similar situation in the future, but for now we are managing to keep the crew safe.”
Station workforce issues
NASA officials at the same briefing addressed another potential safety issue for the ISS: the impact on station operations from the voluntary departures of nearly 4,000 employees, about 20% of the overall NASA civil servant workforce.
There are no immediate effects on the Crew-11 launch, said Steve Stich, NASA commercial crew program manager. “Most people who have chosen to take the deferred retirement program have decided to extend a little longer to get through this particular handover,” he said, referring to the launch of Crew-11 and subsequent return of Crew-10, scheduled for no earlier than Aug. 6.
He said that the program has gotten through many of the planned upgrades to the SpaceX Crew Dragon spacecraft ahead of the personnel departures, including moving splashdown operations to the West Coast, improvements to the spacecraft’s drogue parachutes and heat shield, and working to certify the spacecraft for as many as 15 flights.
“We’re in a similar situation with space station,” said Dana Weigel, NASA ISS program manager. “When you lose folks, or folks choose to leave before the end of the program, it’s really hard to rebuild some of that expertise.”
She noted the staff departures do create opportunities for people who are remaining on the program to move into new roles. “We’re keeping our eye on that and really making sure we’re making the best use of the skills and the talent that we have on the team.”