Russia is trying to figure out how a tiny hole showed up in its Soyuz spacecraft

Russia’s state space corporation is currently investigating what caused a small hole to appear in one of the country’s Soyuz spacecraft that’s currently docked at the International Space Station. The opening caused pressurized air to leak out of the vehicle last week. Originally, Russia thought a small meteorite strike might have caused the hole, but now, the country’s space corporation believes it was made from inside the Soyuz, possibly with a drill. And Russia isn’t discounting the idea that the hole could have been made intentionally — either on Earth or in space.

“We are considering all the theories,” said Dmitry Rogozin, the head of Russia’s Roscosmos state space corporation, according to TASS. “The one about a meteorite impact has been rejected because the spaceship’s hull was evidently impacted from inside. However it is too early to say definitely what happened.” Rogozin goes on to say that it looks like the hole was a “technological error” made by a specialist with a “faltering hand.” “There are traces of a drill sliding along the surface,” he said.

Roscosmos has since convened a State Commission to investigate the cause of the hole. Rogozin noted that understanding its origin was “a matter of honor” and that the investigators would figure out if the hole was the result of a defect or if it was made on purpose. “Now it is essential to see the reason, to learn the name of the one responsible for that. And we will find out, without fail,” he said, according to TASS. NASA declined to go into detail about the investigation. “NASA will support the commission’s work as appropriate,” the space agency said in a statement to The Verge.

Roscosmos says that it plans to finish its investigation sometime this month. “The investigatory commission plans to finish its work in mid-September. All conclusions and decisions will be announced after the commission’s work is completed,” the corporation said in a statement to The Verge.

NASA and Roscosmos first noticed that pressurized air was leaking out of the ISS around 7PM ET on Wednesday, August 29th. However, the leak was so small that NASA did not even alert the crew until the following morning, opting to let them sleep instead. On Thursday, the crew on board the ISS found the cause of the leak: a 2-millimeter hole inside one of the two visiting Soyuz spacecraft. This particular vehicle has been docked to the space station since June 8th, when it brought NASA astronaut Serena Auñón-Chancellor, Russian cosmonaut Sergey Prokopyev, and German astronaut Alexander Gerst to the ISS. The hole is located in one of the capsules of the Soyuz that burns up in Earth’s atmosphere on the way back to the ground.

On Thursday, Prokopyev plugged up the hole using epoxy on a gauze wipe, according to NASA. The fix did the trick, and the space station’s cabin pressure has since stabilized. NASA has been monitoring the pressure levels ever since, and the six crew members on board the space station were able to return to a normal schedule on Friday.

This isn’t the first time that Russia has considered sabotage when investigating a spacecraft failure. In 2012, then-head of Roscosmos Vladimir Popovkin hinted that a foreign country may have been to blame for the failure of a Russian spacecraft Phobos-Grunt. The probe was supposed to explore one of the moons of Mars but instead got stuck in Earth’s orbit and eventually fell back to our planet. But it’s not just Russia that’s conspiracy-minded either. When one of SpaceX’s Falcon 9 rockets exploded in 2016, the company said that it seriously considered sabotage by rival rocket company, the United Launch Alliance, according to Washington Post reporter Christian Davenport. (Neither the SpaceX failure nor the Phobos-Grunt incident turned out to be sabotage.)

But the Soyuz hole is curious. If it was created on Earth, how did it just now start leaking after two months in space? It’s possible that a technician on the ground drilled a hole in the wrong place, realized the mistake, and then tried to patch it up with something that just got dislodged last week. “Perhaps they filled it up with putty or did some attempt at repair but didn’t do a great job with that and after a couple months in space, that repair thing popped out or eroded away,” Jonathan McDowell, an astrophysicist at Harvard and spaceflight expert, tells The Verge.

Or it’s possible that the technician didn’t realize a mistake had been made, and the hole got temporarily plugged anyway. The hole was found behind an insulation panel, according to McDowell, which may have provided coverage during launch and the first couple of months in space. Then something knocked it out of the way, exposing the hole to the inside of the ISS.

Ultimately, there are many different possibilities for how this hole was made on the ground, according to McDowell, and sabotage should be the last option considered. “It seems really implausible the hole wasn’t there at launch,” says McDowell.

Update September 4th, 12:30PM ET: This article was updated to include a statement from NASA and information on plausible scenarios from McDowell.

Update September 5th, 7:50AM ET: This article was updated to include a statement from Roscosmos.