The Soyuz MS-22 spacecraft Konstantin Tsiolkovsky, which launched Expedition 68 crewmembers Sergey Prokopyev, Dmitry Petelin, and NASA’s Frank Rubio on Sept. 21, 2022, returned to Earth in automated mode after suffering a leak in a coolant loop last December.
Cosmonauts Prokopyev and Petelin were preparing to conduct an EVA on the Russian segment of the International Space Station on Dec. 15 when controllers noticed a leak in the Soyuz MS-22 spacecraft’s service module. Flakes coming from the area of the coolant loop were noticed on live camera feeds pointing toward the spacecraft, and as a result, the EVA was canceled.
The coolant loop aboard the Soyuz spacecraft had lost all of its fluid, and a 0.8 mm hole was found in the vehicle’s service module. As a result, the ISS program had to make some important decisions quickly while the spacecraft’s damage was being analyzed. The Soyuz MS-23 flight would now launch to the Station in an automated mode, without crew, as the MS-22 crew’s stay would be extended from this spring to September.
The two Russian cosmonauts would continue to use Soyuz MS-22 as their emergency escape vehicle should a life-threatening emergency aboard ISS require an immediate departure, while Astronaut Frank Rubio’s Soyuz seat liner (lodgement) was moved to the Crew Dragon Endurance for the same purpose. Rubio’s use of Crew Dragon would reduce heat loads if the Roscosmos cosmonauts had to conduct an emergency return on the damaged Soyuz.
Before Soyuz MS-23 docked at the Station, Progress MS-21 also suffered a coolant leak of its own from its service module. The leaks on both spacecraft had occurred after approximately three months in orbit, and both the uncrewed Progress and crewed Soyuz vehicles use the same service module architecture.
This led to the possibility of advancing both the Soyuz MS-23 return and the Soyuz MS-24 launch to June from September. After the MS-22 coolant leak in December, it was thought that it was caused by a micrometeoroid impact. However, the Progress MS-21 leak caused speculation regarding a systemic fault in current Soyuz-based vehicles.
Roscosmos has now declared that both the MS-23 return and MS-24 launch will remain scheduled for September. The MS-22 spacecraft itself is being prepared for an automated return to Earth. MS-22 will utilize the same flight profile and recovery areas in Kazakhstan as it would have with crew onboard.
However, due to the coolant loop failure, the temperature aboard the Soyuz orbital and descent modules had reached 30 degrees Celsius (86 degrees Fahrenheit), while temperatures in the service module had reached up to 40 degrees Celsius (104 degrees Fahrenheit) in the days following the leak. Temperatures have now stabilized to approximately 30 degrees C across the entire spacecraft.
A test, scheduled for five hours, had been conducted aboard Soyuz MS-22 earlier this month, with Cosmonauts Prokopyev and Petelin aboard the spacecraft and wearing their Sokol launch and entry suits. The cosmonauts had permission to bring aboard food and water and could use the system for removing moisture from the air.
However, the crew could not use tablets as they generate heat when turned on. Instead, they had to use paper to make notes. A major concern was that the descent module interior could exceed 31 degrees Celsius at 95 percent humidity, which would start to render the human body unable to shed heat by sweating.
This would create a very dangerous “wet bulb” situation for the cosmonauts, and mission control in Moscow could end the experiment if the temperature and humidity were at these levels. They could also end the test if the crew experienced poor health, if the service module reached 40 degrees Celsius, or if the main computer reached 45 degrees Celsius.
Cosmonaut Andrey Fedyaev would also be in the spacecraft, but without a Sokol suit. The cosmonauts would turn on the ship’s systems and check to see how much the ship would heat during the simulated deorbit and reentry. The test was conducted but the results have not been released by Roscosmos.
The lodgements for all three MS-22 crewmembers have since been moved to the Soyuz MS-23 descent module. MS-23 is now acting as the emergency escape vehicle in addition to being the nominal return vehicle for Prokopyev, Petelin, and Rubio.
Soyuz MS-22 was loaded with 218 kg of cargo — including experiment samples and station equipment — before its undocking at 09:52 UTC on Tuesday, March 28. Once the spacecraft is undocked, Expedition 68 will end and Expedition 69 began. Soyuz started the process for a return to Earth less than two hours after the undocking, with landing at 11:42 UTC.
The MS-22 crew will be busy during the coming months, with a relocation coming up for Soyuz MS-23 from the Poisk module to the Prichal module on the Russian segment. This is to clear the way for several spacewalks by Prokopyev and Petelin to complete the outfitting of the Nauka module.
The EVA tasks include relocating a radiator and an airlock to Nauka. Meanwhile, Roscosmos is preparing for a scheduled Sept. 15 launch of Soyuz MS-24 with Oleg Kononenko, Nikolai Chub, and NASA’s Loral O’Hara. The return of Prokopyev, Petelin, and Rubio after just over a year in low Earth orbit will follow on Sept. 27.
(Lead image: Soyuz MS-22 “Konstantin Tsiolkovsky” docked to the ISS. Credit: NASA)