Gemini IX-A was one of the most eventful and frustrating missions of the Gemini program. Originally designated Gemini 9, the mission was delayed when its Agena Target Vehicle was lost in a launch failure on May 17, 1966. A backup target — the Augmented Target Docking Adapter (ATDA) — was prepared and launched on June 1, but telemetry revealed that its payload shroud had failed to fully separate, leaving the docking collar obstructed. When astronauts Thomas Stafford and Eugene Cernan launched aboard their Gemini spacecraft on June 3 and rendezvoused with the ATDA, they radioed back the now-famous description: it looked like an “angry alligator” with its jaws half-open.

Despite the inability to dock, the crew performed three different types of rendezvous with the ATDA — an equiperiod rendezvous from below, a rendezvous from above, and a rendezvous from below using optical tracking only. These exercises were critical training for the techniques that would later be needed for Apollo lunar missions.

Eugene Cernan then performed a spacewalk lasting over two hours, the second American EVA. However, the spacewalk proved extremely difficult. Without adequate handholds and restraints, every movement required enormous effort, causing Cernan to overheat badly. His visor fogged so severely he could barely see, and his heart rate soared dangerously high. The planned test of the Astronaut Maneuvering Unit (AMU) backpack — essentially a personal jet-pack — had to be cancelled. Cernan’s grueling experience provided crucial lessons that led to better EVA tools, restraints, and underwater training for future missions.

The mission splashed down on June 6, 1966 after three days in orbit and was recovered by the USS Wasp in the Atlantic Ocean. Despite the docking failure and EVA difficulties, Gemini IX-A advanced NASA’s understanding of rendezvous techniques and spacewalk challenges — hard-won knowledge that would prove essential for Apollo.