Soyuz MS-09
The ISS crew traced the leak to a small hole in the orbital module, the top section of the Soyuz MS-09 spacecraft. Credit: NASA

WASHINGTON — As the crew of the International Space Station worked Aug. 30 to fix, at least temporarily, a minor air leak, the incident illustrated the growing orbital debris risk to the outpost and strains in American and Russian approaches to ISS operations.

NASA, in a statement early Aug. 30, said that controllers first noticed a minor drop in air pressure within the station at around 7 p.m. Eastern Aug. 29. Flight controllers allowed the crew to continue sleeping since the pressure drop did not pose an immediate risk to the crew, who were notified of the problem when they woke up at their regular time.

The station’s crew traced the drop in air pressure to a hole about two millimeters in diameter in the orbital module of the Soyuz MS-09 spacecraft docked to the station. They covered the hole with a piece of Kapton tape to slow the rate of the leak temporarily.

In communications with controllers in NASA’s mission control facility in Houston, astronaut Drew Feustel, the commander of the Expedition 56 crew, sought a delay in implementing a permanent solution proposed by Russian controllers, concerned that, if such a fix failed, it might cause further damage to the spacecraft or other jeopardize the ability to fix the leak.

“I would really like to see a test of that, somehow, on the ground before we do a test up here and see if it’s going to work,” he said. “We sort of feel like we’ve got one shot at it and if we screw it up, then the implications are one of these [Soyuz] vehicles is going home, or that vehicle is going home, sooner than later.”

Feustel reiterated a desire for a delay in other conversations with controllers, concerned that Russia wanted to move ahead with a permanent repair immediately. “I’m inclined to request that we have some more time, like 24 hours, to talk about this,” he said. Controllers told him that there were potential alternatives under consideration that NASA engineers were discussing with their Russian counterparts.

Ultimately, though, the Russian space agency Roscosmos elected to move ahead immediately with a more permanent repair, using gauze and epoxy to cover the hole. Russian cosmonauts, speaking through an interpreter, said they were able to successfully cover the hole around 12:30 p.m. Eastern, but were concerned about a bubble that formed in the makeshift patch. Controllers advised them to let the patch harden in place overnight before taking any other steps in the repair.

The cause of the hole is not immediately known. Roscosmos, in a statement, called the hole a “microcrack” and that it had formed a special commission to study the problem.

One potential cause of the hole is an impact with a micrometeoroid or a piece of orbital debris, collectively known as MMOD by NASA. While such objects have struck the station in the past, no such impacts in the past have been linked to air leaks from the station.

“If that’s true, that would be a landmark thing,” said Wayne Hale, a former space shuttle program manager and current member of the NASA Advisory Council, during a meeting of the council Aug. 30 at the Ames Research Center. “If it is, that’s kind of a somber milestone as we talk about MMOD and space traffic management.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...