A leak in the cooling system of Soyuz MS-22 occurred last week due to damage to the spacecraft's outer skin. The cosmonauts reported to ground control that the diagnostic system of Soyuz had been triggered and confirmed that they were visually observing the leak.
Due to the incident, the spacewalk of Russian cosmonauts Sergey Prokopyev and Dmitry Petelin had to be canceled. Russian state-run space agency Roscosmos noted that all of the spacecraft and the ISS's systems were working normally, the crew was safe, and experts would determine what to do next after analyzing the situation.
"It is impossible to repair such damage in the conditions of the International Space Station. Even if you seal the leak during a spacewalk, how can you pump 44 liters of refrigerant into the radiator under the pressure of 3 atmospheres? Moreover, the temperature control system must undergo a special pressure test afterward, which in principle cannot be done in orbit," the source said.
He added that Roscosmos specialists have managed to maintain a comfortable temperature in the living space of the Soyuz MS-22 by shutting down its systems and supplying cooled air from the Russian segment of the ISS.
"However, when the spacecraft is separated from the station and the systems and engines are turned on, its temperature will begin to rise again. This could lead to the failure of its systems despite the rather tight temperature tolerances for the Soyuz systems," the source noted.
Roscosmos said on Monday that the temperature at the spacecraft's instrument-assembly module reached +40 degrees Celsius (104 degrees Fahrenheit) in the first days after the leak and then stabilized at about +30 degrees Celsius after the shutdown of the ship's systems.
According to documentation on thermal management systems for Soyuz MS spacecraft, the temperature in the living space of the spacecraft should be between +18 and +25 degrees Celsius.
On Monday, Roscosmos head Yuri Borisov said the replacement Soyuz MS-23 spacecraft would be ready by March 16 and is currently undergoing pre-flight checks at the Baikonur spaceport in Kazakhstan. He added that he could push forward the launch of the spacecraft to February 19 for the evacuation of the crew should there be any concerns.
On Tuesday, Borisov said that US partners in the ISS have offered to return the crew of the Soyuz MS-22, but there is no necessity for it today.