Sokol Space Suit - Operational Use

Operational Use

Each Soyuz crew member is provided with a made-to-measure suit for flight although, from the numbers made, it appears that the suits provided for ground training are re-used. It is considered vital that the flight suit fits correctly and the wearer will spend two hours sitting in a launch couch with the suit inflated to make sure of this. Straps on the arms, legs and chest allow the fit to be adjusted slightly.

To don the suit, the two zips that make a 'V' on the chest are opened. Underneath, there is a large tubular opening in the inner pressure layer known as the appendix. Legs go in first, followed by the arms into the sleeves and head into the helmet. When the suit is on, an airtight seal is made by tightly rolling up the appendix and securing it with strong elastic bands. The large bulge of the rolled-up appendix is secured under the V shaped flap in the suit's outer layer. When worn on the ground, the suit is attached to a portable ventilation unit —a hand-held device that supplies air to the suit, cooling it first with an ice filled heat exchanger. Grey leather outer boots are also worn on the ground; they protect the feet of the suit from damage and are removed before entering the spacecraft to avoid carrying debris into the cabin.

The suit is worn during launch and re-entry of the Soyuz spacecraft—the gloves are attached and the visor is sealed at these times. In an emergency the suit pressure is usually maintained at 400 hPa (0.39 atm, 5.8 psi) above the ambient by the pressure relief valve. However, the suits only have a rudimentary pressure relief layer so they tend to balloon when inflated. Movement of the wearer becomes restricted, although it is still possible to function inside the capsule.

If more than limited movement is required, the pressure relief valve may be adjusted to a lower setting of 270 hPa (0.26 atm, 3.9 psi). Pure oxygen at this pressure will support life, but the setting is only intended for use in extreme emergencies; the risk of decompression sickness becomes significant if the wearer spends more than 15 minutes at the lower pressure setting.