A mysterious leak discovered last week on the International Space Station is baffling scientists and countries alike, reports the Atlantic.

On August 30, flight controllers on earth found a decrease in air pressure on-board the ISS, alerting them about a possible leak on the space station. As of now, six astronauts — including three Americans, two Russians, and a German — are inhabiting the station, but NASA didn’t immediately alert them of the leak because they were sleeping at the time of the discovery and the leak was not considered alarming enough.

However, they were told to look for the source of the leak as soon as they woke up, and on inspection, astronauts found a tiny hole in the Russian-made Soyuz capsule which is used to transport astronauts to and from earth. The discovery was alarming since Soyuz is the only option astronauts have of traveling back to earth, with the United States ending its space shuttle program back in 2011. The capsule is supposed to bring the ISS astronauts back to earth in December, and it is fortunate engineers found the hole now, considering it could have proved fatal later.

Astronauts quickly used Kapton tape, a type of adhesive which works even in extreme temperatures, to plug the hole. Later, the hole was covered using a sealant, but exactly how it came about is causing a lot of consternation for officials on earth.

Soon after the discovery, there was widespread consensus that the hole could have been caused by a micrometeoroid, extremely tiny space debris which travel at speeds fast enough to cause damage to metals. But unbelievably, that theory was thrown out this week when the Russian Space Agency realized that the hole was made from inside the capsule.

ISS Leak summary:



First thought was MMOD strike.



Then NASA released pics. Lots of people: "Hmmm, doesn't look like MMOD". NASA deleted the photos.



Top Russian news site RIA NOVOSTI reported - via sources but apparently confirmed by Mr. Rogozin - it was a drill hole. pic.twitter.com/520kHK0TMc — Chris B - NSF (@NASASpaceflight) September 3, 2018

This has prompted speculation on how the hole was created, with the Russian Space Agency convening a meeting with its international counterparts on September 10. While we might know the exact cause for the mysterious hole until well after that meeting, there have been murmurs suggesting that Russia believes the hole could be a work of sabotage.

“It is too early to say definitely what happened. But, it seems to be done by a faltering hand,” said Dmitry Rogozin, the chief of Russia’s space agency.

“It is a technological error by a specialist. It was done by a human hand. There are traces of a drill sliding along the surface. We don’t reject any theories.”

The scariest part is that Russia is not even ruling out the possibility that the hole could have been made before the capsule was used to transport astronauts from earth.

Rogozin has pledged to “find the one responsible for that, to find out whether it was an accidental defect or a deliberate spoilage and where it was done—either on Earth or in space.”

Russia and the United States have promised to work in tandem to find the culprit, but for now, the mystery deepens.