On June 3, 1965, 120 miles above the Earth, Major Edward H. White II opened the hatch of the Gemini 4 and leaves the capsule, becoming the first American astronaut to walk in space. Attached to the craft by a 25-foot lanyard and controlling his movements with a hand-held oxygen jet pistol, White remained outside the capsule for just over 20 minutes. As a space walker, White was preceded by the Soviet cosmonaut Aleksei A. Leonov, who on March 18, 1965 was the first man to walk in space.
Implemented at the height of the space race, NASA’s Gemini program was the least famous of the three US-led space programs conducted in the 1960s. However, as an extension of the Mercury project, which put the first American into space in 1961, Gemini laid the groundwork for the more spectacular Apollo lunar missions, which began in 1968.
Gemini space flights were the first to involve multiple crews, and the extended duration of the missions provided valuable information on the biological effects of longer-term space travel. By the end of the Gemini program in 1966, American astronauts had also perfected rendezvous and docking maneuvers with other vehicles in orbit, a skill that would be essential during three-stage missions to the Apollo moon.