The launch of the Gemini 9 mission was delayed two days after the occurrence of some ground equipment failure. The Gemini 9 mission launched on June 3rd with the primary objectives of practicing maneuvers that would be carried out on the Apollo missions, test the Astronaut Maneuvering Unit with a spacewalk, and test the spacecraft's precise landing abilities. Throughout the duration of the mission, five scientific experiments were accomplished as well. The mission suffered many problems due to equipment problems. The Augmented Target Docking Adapter was launched earlier for docking practice, but it was discovered that the launch shroud failed to deploy and blocked the docking port. Instead, several spacecraft maneuvers were practiced instead.
When it came time for the intended 45-meter spacewalk, Cernan was released from the aircraft with an 8 meter tether. He found it extremely difficult to move around the spacecraft to the AMU. However, after finally mounting the AMU, they discovered that the process required much more work than imagined and Cernan's faceplate fogged up, forcing him to return to the spacecraft. Despite the issues, it was the longest spacewalk in history, at about two hours.
The Gemini 8 spacecraft performed reentry and was recovered in the Atlantic Ocean. Although the mission was plagued by problems, it was still deemed a success.