This water cooling suit (WCS) is designed to remove excess heat from a cosmonaut’s body when they are working in a space suit. When working in open space, the body sweats and heats up. Because the cosmonaut is wearing a hermetically sealed spacesuit, this can quickly make it very difficult for them to continue working. In order to ensure the cosmonaut can work at a comfortable temperature the Russian Orlan space suits are equipped with a thermoregulation system which allows ventilation and uses water to cool the suit.

The water cooling system consists of the water cooling suit itself, plus a pump to keep the water circulating through the pipes in the suit, and a sublimation heat exchanger, which cools the water. The WCS is a mesh jumpsuit made of knitted material. The material’s mesh structure allows for better ventilation. Thin polyvinyl chloride tubes, with a diameter of 1.5-2.6 mm are sewn into the fabric of the garment, and water circulates through these tubes.

Because it is in contact with the surface of the cosmonaut’s body, the suit removes excess heat and reduces perspiration. The WCS is connected to the space suit through two channels, an entry and an exit channel. The water is poured into the suit using the opening in the back of the space suit. The water is enriched with silver ions, which help increase its service life. The back of the suit also contains a sublimator, which cools the water. There are two separate circuits through white water flows: in one circuit the water passes through the sublimator and is cooled, while in the other the water stays warm.

In the first versions of the Orlan space suit the cosmonauts themselves regulated the temperature of the suit by hand, depending on how they felt, by using the hot/ cold tap. The most recent version, the Orlan MKS, is equipped with an automatic thermal regulation system, which uses carbon dioxide sensors to determine the cosmonaut’s level of physical activity, and therefore to determine the appropriate temperature of the water pumped through the suit. This makes it more convenient to work in the space suit, as it reduces the number of operations that the wearer needs to do to ensure a stable temperature, and it also makes it safer to work in open space.

The current version — WCS-M, weighs about 3 kg when the tubes are filled with water. The total length of the tubes in the suit is about 65 meters. The suits are manufactured in four sizes. They are manufactured by Zvezda Scientific Production Company, in Tomilino, Moscow region, which develops and manufactures a range of life-support systems for cosmonauts.