Gemini 11

Gemini 11 carried Pete Conrad and Richard Gordon from September 12 to 15, 1966. The crew rendezvoused and docked with an Agena during their first orbit, demonstrating a rapid approach relevant to Apollo's lunar-orbit rendezvous plan. Agena propulsion later raised the docked spacecraft to an apogee of about 1,374 kilometers before returning them to a lower orbit. Gordon's first spacewalk was cut short after attaching a tether proved exhausting and perspiration impaired his vision. A later stand-up EVA supported photography, and the crew experimented with the two vehicles connected by a 30-meter tether, including slow rotation. They also completed another rendezvous before returning to Earth. Gemini 11 demonstrated the first computer-commanded, closed-loop automatic reentry in the U.S. space program. Its successes in rapid rendezvous, docked propulsion, and landing guidance were accompanied by another warning that unsupported manual work during EVA could overwhelm an astronaut's strength and suit cooling.