Late last week, as the Astronaut and Cosmonaut crew of the International Space Station slept, controllers noticed a slight but obvious drop in air pressure. The drop wasn’t considered life threatening, so the decision was made to leave the crew sleeping and inform them in the morning. Once the crew got up, the hunt was on to identify what might have been causing the issue.

What they found was deeply troubling: a tiny hole, nearly two millimeters in diameter, had developed in the exterior hull of the Russian Soyuz MS-08 spacecraft attached to the station, venting oxygen into the great beyond. The hole was small and manageable, the crew agreed, with ESA astronaut Alexander Gerst even sealing it temporarily with a finger as the rest of the team found materials for a make shift seal. It was immediately apparent that a longer term solution had to be found, and ground teams in both Russia and the United States set about finding the best, and safest, way to address this pressing concern. In the mean time, the crew sealed the hole using epoxy and a piece of Kapton tape — a high strength tape commonly used aboard spacecraft.

It wasn’t long before word came up from Roscosmos to implement a more permanent solution to the problem, but NASA astronaut and mission commander Drew Feustel requested they delay implementing the Russian solution until after it could be tested on the ground — noting that they’d have only one opportunity to execute the fix in orbit, and seemingly concerned about their chances of success under the Russian strategy.

A Soyuz capsule docked on the ISS during a previous mission. (NASA)

“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.”