Gemini 9A lifted off from Cape Kennedy carrying astronauts Tom Stafford and Eugene Cernan on a three-day mission to practice rendezvous and docking techniques essential for the coming Apollo program. The mission followed the failed launch of its original Agena target vehicle in May, and though docking again proved impossible due to a shroud malfunction on the substitute target, Cernan completed a grueling two-hour spacewalk that exposed the dangers of extravehicular activity.
Gemini 9 almost didn't happen at all. Its original docking target, an Atlas-Agena vehicle, had plunged into the Atlantic on May 17, 1966, after a guidance failure, forcing NASA to substitute a backup Augmented Target Docking Adapter (ATDA). When Stafford and Cernan finally launched on June 3 and caught up with the ATDA in orbit the next day, they found its protective shroud had failed to separate, leaving the target vehicle looking, in Stafford's memorable description, like 'an angry alligator' — impossible to dock with safely.
Undeterred, the crew practiced rendezvous maneuvers instead. On June 5, Cernan ventured outside for what became an exhausting, near-disastrous spacewalk; without adequate handholds or restraint systems, he overheated dangerously, his visor fogged, and he struggled for over two hours to complete tasks that had looked simple on paper.
The mission became an unglamorous but essential lesson: engineers realized spacewalks demanded far better training and equipment, insights folded directly into later Gemini flights and the success of Apollo's own EVAs.