Soyuz MS-09

Air leak

On the night of 29 August 2018, ground control detected a small air leak in the ISS. A 2 mm hole was found in the orbital module, later described as having been hidden with a low-quality patch job. Russian crew members temporarily sealed the leak with Kapton tape while a permanent repair was prepared.

The leak was successfully sealed using an epoxy sealant repair kit, and no further pressure changes were noted as of 31 August. On 4 September 2018, it was announced that the hole had been created by a drill, though it remained unclear whether the drilling was accidental or deliberate. Russian officials suggested the hole might have been sabotage, possibly during the module's manufacturing, and some speculated that a NASA crew member had drilled it.

On 11 December 2018, Oleg Kononenko and Sergey Prokopyev performed an EVA, cutting into thermal blankets and removing insulation to examine the external hull, take images, and collect residue samples for investigation. Because the hole was in the orbital module, which is jettisoned before re-entry, the return flight was not endangered. The MS-09 crew's return was briefly delayed by the launch failure of Soyuz MS-10, until the arrival of the next crew on MS-11. MS-09 landed on 20 December at about 05:03 UTC.

Further reports and investigations followed. Prokopyev stated that the drill hole was made from the inside, but the timing of its creation was unclear. NASA officials said they knew exactly when the leak began and that no US astronauts were reportedly near the Russian segment where the Soyuz was docked. In September 2019, Roscosmos head Dmitry Rogozin claimed the agency knew exactly what happened but would keep the information secret.

On 20 April 2021, the Russian tabloid Moskovskij Komsomolets published an article citing a Facebook post by Vadim Lukashevich that claimed the hole was drilled by Serena Auñón-Chancellor after a blood clot developed in her jugular vein—a medical case that did occur—which NASA disputed and Ars Technica called preposterous. The results of a Roscosmos investigation were later handed to law enforcement authorities in late 2021, with state media promoting a new theory that Auñón-Chancellor drilled the hole while suffering psychologically after a failed romantic relationship with a crew member.