Gene Kranz's laminated badge for the NASA Manned Spacecraft Center, Mission Control Center—Houston, 2.25 x 3.75, stamped with his name, "Kranz, Eugene F.," noting the mission as Gemini "8," with "A" and "V" stamped below. In fine condition. Accompanied by a signed letter of authenticity from Kranz, in part: "The Gemini 8 MCC badge issued in my name that accompanies this letter, is from my personal collection of space memorabilia." Gemini 8 was the first spaceflight for future moonwalkers Neil Armstrong and Dave Scott, and represented the first docking of two spacecraft in orbit. During the docking sequence, an OAMS thruster became stuck open which sent the Gemini capsule into a rapid tumble, putting the astronauts' lives at risk. Thinking quickly under pressure, Armstrong shut down the OAMS and used the RCS thrusters to regain control of the spacecraft. The remainder of the mission had to be aborted. Armstrong's decision came under scrutiny, but Kranz defended him, writing that 'the crew reacted as they were trained, and they reacted wrong because we trained them wrong.' The mission planners and controllers had failed to realize that when two spacecraft are docked together, they must be considered to be one spacecraft. Kranz considered this the most important lesson of Gemini 8.