On This Day In History in 1965: First American Space Walk

On June 3, 1965, one hundred and twenty miles above the earth, Major Edward H. White II opens the hatch of the Gemini 4 and steps out of the capsule, becoming the first American astronaut to walk in space. Attached to the craft by a 25-foot tether and controlling his movements with a hand-held oxygen jet-propulsion gun, White remained outside the capsule for just over 20 minutes.

NASA's Gemini program was the least famous of the three U.S.-manned space programs conducted during the 1960s. The Gemini space flights were the first to involve multiple crews, and the extended duration of the missions provided valuable information about the biological effects of longer-term space travel. When the Gemini program ended in 1966, U.S. astronauts had also perfected rendezvous and docking maneuvers with other orbiting vehicles, a skill that would be essential during the three-stage Apollo moon missions.