An unexplained leak from the Soyuz MS-22 spacecraft, which is currently docked to the International Space Station (ISS), has jeopardized its return to Earth, the Ars Technica outlet reported on Dec. 15.
A Russian spacewalk was canceled at the last minute on the night of Dec. 14 when the spacecraft attached to the ISS unexpectedly sprang a large leak.
Cosmonauts Sergey Prokopyev and Dmitri Petelin were dressed in spacesuits, with the airlock depressurized, when flight controllers told them to standby while the leak from the Soyuz spacecraft was investigated.
The leak appears to have originated in an external cooling loop located at the aft end of the Soyuz MS-22 spacecraft. The substance leaking could be ammonia, which is used as a coolant for spacecraft.
Russian officials have not yet confirmed this assumption.
According to Ars Technica, at no time were any of the crew members on the space station in danger, including Prokopyev and Petelin, their fellow cosmonaut Anna Kikina; NASA astronauts Frank Rubio, Nicole Mann and Josh Cassada; and Japanese astronaut Koichi Wakata. The leak was external to the station, not inside the orbiting laboratory.
However, the leak does raise questions about the viability of the Soyuz spacecraft, which is the ride back to Earth for Prokopyev, Petelin, and NASA’s Frank Rubio. They launched to the space station back in September on board this Soyuz vehicle, and are due to return to Earth next spring.
After three hours Monday night the leak remained ongoing, showing no sign of abating.
The Soyuz is a hardy spacecraft, so it is plausible that there may not be any impact on its ability to undock from the space station and return to Earth. However, if Russian engineers – and those from NASA, considering that Rubio will be on board – determine there is an issue, a replacement Soyuz would need to be flown up to the station.
The other four astronauts on board the station flew up on a SpaceX Crew Dragon spacecraft in October. That vehicle cannot accommodate seven people for a return to Earth.
Given the long duration of the leak, NASA is also likely to have concerns about the impact of all that ammonia on space station surfaces and those of other docked vehicles. Much of the ammonia would probably boil off the surface of the hardware over time, but it will certainly complicate operations as the U.S. space agency works toward conducting a spacewalk of its own on Dec. 19 to install new solar arrays.