The first spacewalk was performed

On March 18, 1965, Soviet cosmonaut Alexei Leonov opened the airlock of Voskhod 2 and drifted into the vacuum, becoming the first human to walk in space. Tethered to the capsule, he floated free above the Earth for about 12 minutes, beginning over north Africa and ending over Siberia.

The triumph nearly ended in disaster. In the vacuum, Leonov’s spacesuit ballooned so much that he could not bend his joints to climb back through the narrow airlock. With his oxygen reserves dwindling, he secretly bled pressure from the suit — pushing below safety limits — until he could squeeze inside.

The first steps outside a spacecraft proved that humans could work in open space, a prerequisite for everything from Moon landings to station assembly.

The feat handed the Soviet Union another early space-race milestone, beating the United States’ first spacewalk by less than three months.