On Apr. 6, Sojuz MS-23 will undock from the Poisk module and be relocated to the Prichal module.
Meanwhile, cosmonauts Sergei Prokopiev, Dmitry Petelin, and Andrei Fedyaev checked the tightness of the Sokol-KV2 spacesuits.
Previously they mounted in the SA (from Russian spuskáyemy apparát: descent module) section of the Soyuz, which arrived on the ISS unmanned, the Kazbekh-UM seats, that were installed on the Sojuz MS-22, which recently returned to earth in automatic mode.
Sojuz MS-23 launched uncrewed from the Baikonur Cosmodrome on Feb. 23, was initially assigned to the mixed Russian-American crew of Commander Cosmonaut Oleg Kokonenko, Pilot Cosmonaut Nikolai Chub, and NASA Astronaut Loral O ‘Hara. Following the loss of refrigerant from the SOTR (from Russian Systema Obespecheniya Teplovogo Rezhima: Thermal control system), the cooling and conditioning circuit of the Sojuz MS-22, which occurred on Dec. 14, 2022, probably caused by the impact of a micrometeorite, the same spacecraft was declared unavailable for the return of the original crew, i.e. the Cosmonauts Prokopiev, Petelin, and Astronaut Rubio.
After a careful study by NASA and Roscosmos technicians, it was decided to send the Soyuz MS-23 in fully automatic mode to act as a rescue ship for the crew that left with the MS-22.
The same Sojuz MS-22, damaged, was used as a transport vehicle and, deprived of the Kazbekh-UM seats, returned to the ground in automatic mode. The return took place, without particular problems, on Mar. 28.
An integrated system
It should be remembered that the Sojuz has an integrated shock absorption and life support system that includes Sokol KV-2 semi-pressurized suits and Kazbekh-UM pods. Both of these two components are tailor-made for the individual occupant. Hence they need to remove the seats from the MS-22 and transport them to the MS-23 which departed without them.
To reach the ISS, the Sojuz MS-23 followed a low-power trajectory, bringing it to dock approximately 48 hours after launch. This was necessary to save fuel in the spacecraft’s thrusters in anticipation of any numerous docking attempts in the event of a malfunction of the KURS-NA (from the Russian Kurs: course) automatic approach and docking system
Why move the Sojuz?
The movement of the Sojuz MS-23 from the docking hatch of the Poisk module to the Prichal node is necessary to allow a safe exit of the cosmonauts Prokopiev and Petelin during the scheduled EVA-57, scheduled for the current month of April, in which they will have to relocate an airlock module from the Rassvet module to the Nauka module.