Commanded by Gemini VII veteran James A. Lovell, the flight featured three periods of extravehicular activity (EVA) by rookie Edwin "Buzz" Aldrin, lasting a total of 5 hours and 30 minutes.

On Gemini 12, the fuel tank appeared to have also ruptured as a white cloud was seen emitting from the spent stage along with the orange nitrogen tetroxide.

Another episode of "Green Man" also occurred at SECO, referring to pitch gyrations caused by pressure buildup in the second stage protective skirt.

[4] Aldrin's two-hour, 20-minute tethered space-walk, during which he photographed star fields, retrieved a micrometeorite collector and did other chores, at last demonstrated the feasibility of extravehicular activity.

Following Gemini 12's reentry and during the GATV's 63rd orbit, they attempted to fire the propulsion system, but a stuck fuel valve prevented engine start from occurring.

The inability of ground controllers to start the engine during the 63rd orbit was possibly due to melted or loose debris blocking the fuel valve and preventing its operation.

[6] However, the 2016 article "Inventing Underwater Training for Walking in Space," by Michael Neufeld reveals that neutral buoyancy experimentation began at aerospace companies and at NASA Langley Research Center in Hampton, Virginia a few years before the first Gemini mission had even flown.

When Gemini 12 was being planned, one of the possibilities raised was the potential for the flight to be run in conjunction with the first Apollo mission, which had been tentatively scheduled for the last quarter of 1966.

Both were slightly exhausted and dehydrated due to problems with the spacecraft's water supply system forcing them to reduce their fluid intake on the last day of the mission and Lovell had a mild case of pinkeye.

Lovell and Aldrin were reunited with the spacecraft on November 9, 2006 during the opening for Adler's "Shoot for the Moon" exhibit, almost 40 years after the mission launched.