Gemini 9A was the seventh crewed Earth-orbiting spacecraft of the Gemini series. It carried astronauts Tom Stafford and Gene Cernan. Primary mission objectives were to demonstrate (1) rendezvous techniques and docking with a target vehicle to simulate manuevers to be carried out on future Apollo missions, (2) an ExtraVehicular Activity (EVA) spacewalk to test the Astronaut Maneuvering Unit (AMU), and (3) precision landing capability. Scientific objectives included obtaining zodiacal light and airglow horizon photographs. Two micrometeorite studies were to be carried out, and there were also one medical and two technological experiments.
The mission was originally scheduled for launch (as Gemini 9) on 17 May but was postponed when the Gemini Agena Target Vehicle failed to achieve orbit due to a booster failure earlier that day. The replacement Augmented Target Docking Adapter (ATDA) was launched successfully into Earth orbit on 1 June, but telemetry indicated that the shroud had failed to jettison properly. Gemini 9 was to launch shortly thereafter but ground equipment failure resulted in a postponement until 3 June.
Gemini 9A was launched on 3 June from Complex 19 at 8:39:33 a.m. EST (13:39:33.335 UT) and inserted into a 158.8 x 266.9 km orbit. After three orbital maneuvers, rendezvous within 8 meters of the ATDA was achieved on the third revolution. It was confirmed that the launch shroud on the ATDA had failed to deploy and was blocking the docking port. The flight plan was then revised to include two equiperiod passive rerendezvous maneuvers in place of the docking. The first, using optical techniques without on-board radar, was completed at 3:15 p.m. EST, and the second, a rendezvous from above simulating rendezvous of an Apollo command module with a lunar module after abort from the Moon, was completed at 6:21 a.m. EST on 4 June and final departure from the ATDA took place at 7:38 a.m. The scheduled EVA was postponed due to crew fatigue and the second day was devoted to experiments.