Why the first spacewalkers struggled to re-enter their own spacecraft

Nature · Published 3 October 2026 Swipe more like this →

In short: Space is a vacuum that turns a suit into a rigid balloon. When Alexei Leonov performed the first spacewalk in 1965, his suit stiffened so severely that he became trapped in his airlock. This dangerous reality of extravehicular activity remains a primary focus for modern lunar exploration technology development.

Extravehicular activity (EVA) encompasses any work performed by an astronaut outside a spacecraft, whether in low Earth orbit or on a planetary surface. NASA’s current Extravehicular Activity and Human Surface Mobility Program is a cornerstone of the Artemis mission, tasked with developing next-generation spacesuits, pressurized rovers, and the essential support systems required for humanity’s return to the Moon and eventual deep space exploration.

The history of EVA is marked by technical ingenuity and hidden peril. During the first spacewalk on March 18, 1965, Soviet cosmonaut Alexei Leonov spent over 12 minutes in the vacuum of space. His suit ballooned due to internal pressure, making it nearly impossible to move. Upon attempting to re-enter his capsule, he became stuck in the airlock, forcing him to dangerously reduce his suit's pressure to squeeze back inside. While the Soviets initially misrepresented the difficulty of this mission, the reality was that Leonov was significantly overheated and physically trapped.

Modern training has evolved far beyond these early, improvised efforts. NASA now utilizes facilities like the Neutral Buoyancy Laboratory and the Prototype Immersive Technologies Lab to prepare astronauts for the specific challenges of lunar operations, such as navigating permanently shadowed regions. By leveraging commercial partnerships, NASA aims to foster industry innovation, ensuring that the tools developed for Artemis—from advanced suits to lunar terrain vehicles—are robust enough to support a sustainable human presence on the Moon and beyond.

The evolution of EVA technology reflects a shift from survival to sustained exploration. While early missions were defined by the immediate need to solve mechanical failures, such as the hatch issues faced by Ed White during the 1965 Gemini IV flight, today’s program focuses on long-term capability. By sharing technical documentation and design requirements, NASA is facilitating a broader industry ecosystem that benefits both the taxpayer and the future of deep space travel.

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