The astronaut maneuvering unit (AMU), which had been installed in Gemini spacecraft No. 12 on September 17, was removed as the spacecraft was undergoing final preparations for movement to complex 19. NASA Headquarters deleted the AMU experiment from the extravehicular activities (EVA) planned for the Gemini XII mission.

Persistent problems in performing EVA on earlier flights had slowed the originally planned step-by-step increase in the complexity of EVA. With only one flight left, George E. Mueller, NASA Associate Administrator for Manned Space Flight, felt that more work was required on EVA fundamentals - the performance of easily monitored and calibrated basic tasks. On this flight, the pilot would remove, install, and tighten bolts, operate connectors and hooks, strip velcro, and cut cables.