The first spacewalk disaster: How Alexei Leonov nearly became stranded in space during humanity’s most daring mission

Published 8 June 2026 · science

Image: Space How Alexei Leonov made history with the world’s first spacewalk aboard Voskhod 2 Why Leonov’s spacesuit ballooned in the vacuum of space and

Image: Space How Alexei Leonov made history with the world’s first spacewalk aboard Voskhod 2 Why Leonov’s spacesuit ballooned in the vacuum of space and nearly trapped him outside The risky oxygen release that saved the first spacewalker’s life The first man to ever take steps outside the confines of the spacecraft was Soviet cosmonaut Alexei Leonov on March 18, 1965. What at first seemed like a victory in the highly competitive Space Race very quickly developed into a fight for Leonov’s life. While out floating above Earth, Leonov experienced problems with his spacesuit expanding in the conditions of outer space due to the vacuum and became unable to move, let alone enter the spacecraft through the airlock as he had planned to do. Forced by time constraints to act fast or else die, Leonov released oxygen from his suit and took the risk of suffering from decompression sickness in order to reenter the spacecraft and survive. Leonov’s story of bravery is one of many, showing just how daring people had to be during those pioneering days of space travel.Voskhod 2 was launched by the Soviets, carrying two cosmonauts aboard, namely, Alexei Leonov and Pavel Belyayev.

In simple terms, the main goal of this journey was to take a person outside a spacecraft and bring him back safely.Approximately 500 kilometres above the Earth’s surface, Leonov ventured out using an inflated airlock, floating in the emptiness of space, attached to the spacecraft by means of a tether line.The venture lasted only about 12 minutes, making Leonov the first man to perform the extravehicular activity in outer space.Leonov told Smithsonian Magazine while recollecting this incident years later, Leonov stated:“I could hear myself breathe and even hear my own heartbeat in the silence of space.”This great feat made sure that the Soviets were still ahead of their competitors in the Space Race, showing that people can live and work in outer space.The celebration was short-lived. In the vacuum of space, Leonov's Berkut spacesuit expanded far more than engineers had anticipated. The suit stiffened dramatically, making movement increasingly difficult. His hands and feet shifted inside the suit, and he struggled to bend his limbs. Most critically, the inflated suit became too large for the narrow airlock of Voskhod 2.With the spacecraft approaching orbital darkness, Leonov realised he might not be able to return before visibility disappeared.

According to later accounts, he understood that he had only minutes to solve the problem.In his memoir published by the Smithsonian's Air & Space Magazine, Leonov recalled the exhilaration and danger of the mission, describing his feeling while outside the spacecraft as:“Like a seagull with its wings outstretched, soaring high above the Earth.”Yet beneath that wonder, a potentially fatal crisis was unfolding.Unable to fit through the airlock, Leonov made a decision that mission controllers had not authorised in real time. He manually opened a valve and reduced the pressure inside his spacesuit, allowing excess oxygen to escape. The procedure made the suit more flexible, but it also exposed him to the danger of decompression sickness, commonly known as "the bends".And indeed, it paid off. By allowing the pressure inside the suit to equalise to that of outer space, Leonov finally managed to squeeze himself back into the capsule. There have been controversies about certain aspects of this maneuver later on, but one thing stands firm: the spacesuit had expanded in the vacuum of space, thus making it necessary to release some of the oxygen.However, trouble wasn't over yet.