Lunar orbit
The Gemini spacecraft would have rendezvoused with stacked Centaur and Agena upper stages in low Earth orbit. The Centaur would have placed the Gemini and Agena onto a circumlunar trajectory, along which they would coast until they reached the Moon. The Agena would then have been used to perform Lunar orbit insertion. Following the completion of activities in Lunar orbit, the Agena would have been fired again for trans-Earth injection.