Gemini XII was the tenth and final crewed mission of the Gemini program, and it ended the series on a triumphant note. Launched on November 11, 1966, the mission carried Command Pilot James Lovell and Pilot Edwin “Buzz” Aldrin into orbit from Cape Kennedy Launch Complex 19 atop a Titan II GLV rocket. The mission’s primary objective was to prove that extravehicular activity (EVA) could be performed safely and routinely — a goal that had eluded several previous Gemini crews.

Previous Gemini EVAs had been plagued by problems. Astronauts overheated, fogged their visors, and exhausted themselves fighting against the stiffness of their pressurized suits. Gene Cernan on Gemini IX-A and Richard Gordon on Gemini XI both returned to the cabin drenched in sweat and near exhaustion. For Gemini XII, NASA took a different approach: Aldrin trained extensively underwater at a neutral buoyancy facility, the first astronaut to do so, rehearsing each EVA task in conditions that closely simulated the weightlessness of space.

The preparation paid off spectacularly. Aldrin performed three EVAs totaling five hours and thirty minutes — a standup EVA from the open hatch, a two-hour umbilical EVA outside the spacecraft, and another standup EVA. He worked calmly and methodically, using foot restraints and handholds to maintain position while performing tasks like connecting and disconnecting electrical connectors, using tools, and attaching a tether between the Gemini capsule and the Agena target vehicle. His heart rate barely rose above resting levels.

Beyond the EVA triumph, Gemini XII also demonstrated tethered station-keeping with the Agena, though the planned high-altitude boost was canceled due to an Agena anomaly. The crew conducted scientific experiments and captured stunning photographs of a solar eclipse visible from orbit. The mission splashed down in the Atlantic Ocean on November 15, 1966, and was recovered by the USS Wasp. Gemini XII closed out the Gemini program having achieved all the objectives NASA needed before moving on to Apollo: rendezvous, docking, EVA, and long-duration flight were now proven capabilities.