How a tragic spacecraft depressurization changed the design of spacesuits forever

Space · Published 8 October 2026 Swipe more like this →

In short: In 1971, a Soyuz 11 crew perished because they were not wearing spacesuits during their return to Earth. This tragedy led to the creation of the Sokol, a specialized emergency survival system designed to protect astronauts during the most dangerous phases of flight.

Created by RD&PE Zvezda, the Sokol spacesuit—named after the Russian term for Falcon—was designed specifically after the 1971 Soyuz 11 catastrophe. Following that loss, the suit was introduced in 1973 to ensure cosmonauts could survive accidental depressurization during launch or return to Earth. The design evolved from high-altitude aviation gear, with Zvezda replacing rigid, removable helmets with softer, built-in versions to allow for near-instant sealing when the visor is closed.

The suit's architecture is a dual-layer system. An internal rubberized bladder provides the airtight seal, while a rigid external coat made largely of the temperature-stable insulator Kapton protects against thermal and mechanical impacts. To ensure a perfect fit, every suit is made-to-measure for the specific crew member. To ensure a proper fit, astronauts undergo sixty minutes in a launch seat while the suit is inflated, using chest, leg, and arm straps for precise tuning.

Donning the suit is a precise process. A wearer enters through two chest zips that form a 'V' shape, sliding their legs and arms into place before the head enters the helmet. An opening in the inner bladder, known as the appendix, is rolled up tightly and secured with elastic bands to maintain pressure. Once inside the Soyuz spacecraft, the suit is connected to life-support via electrical and air supply lines attached to the lower abdomen.

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