Roscosmos revealed how the Gagarin Cosmonaut Training Center (GCTC) prepares crews for spacewalks: for training, a hydrolaboratory with a tank of 5000 m³, 23 meters in diameter and 12 meters deep, is used.
Inside, cosmonauts in Orlan spacesuits practice operations that they will perform on the exterior of the International Space Station. For this purpose, full-size mock-ups of the modules of the Russian segment of the ISS are lowered into the water. A special platform allows them to be placed at the required depth and moved during training.
Water helps create the effect of weightlessness due to neutral buoyancy: it is achieved by regulating the cosmonaut's buoyancy in the spacesuit with the help of special weights. In such conditions, crews can practice moving along handrails, working with equipment, and servicing station elements.
There are 45 portholes on the walls of the tank underwater. Through them, instructors observe the actions of the cosmonauts, and specialists conduct photo and video recording of the training sessions.