to open or close fifteen latches simultaneously. Docking assembly Apollo's mission required the LM to dock with the CSM on return from the Moon, and also in the transposition, docking, and extraction maneuver at the beginning of the translunar coast. The docking mechanism was a non-androgynous system, consisting of a probe located in the nose of the CSM, which connected to the drogue, a truncated cone located on the lunar module. The probe was extended like a scissor jack to capture the drogue on initial contact, known as soft docking. Then the probe was retracted to pull the vehicles together and establish a firm connection, known as "hard docking". The mechanism was specified by NASA to have the following functions: Allow the two vehicles to connect, and attenuate excess movement and energy caused by docking Align and center the two vehicles and pull them together for capture Provide a rigid structural connection between both vehicles, and be capable of removal and re-installation by a single crewman Provide a means of remote separation of both vehicles for the return to Earth, using pyrotechnic fasteners at the circumference of the CSM docking collar Provide redundant power and logic circuits for all electrical and pyrotechnic components. Coupling The probe head located in the CSM was self-centering and gimbal-mounted to the probe piston. As the probe head engaged in the opening of the drogue socket, three spring-loaded latches depressed and engaged. These latches allowed a so-called 'soft dock' state and enabled the pitch and yaw movements in the two vehicles to subside. Excess movement in the vehicles during the 'hard dock' process could cause damage to the docking ring and put stress on the upper tunnel. A depressed locking trigger link at each latch allowed a spring-loaded spool to move forward, maintaining the toggle linkage in an over-center locked position. In the upper end of the lunar module tunnel, the drogue, which was constructed of 1-inch-thick aluminum honeycomb core, bonded front and back to aluminum face sheets, was the receiving end of the probe head capture latches. Retraction After the initial capture and stabilization of the vehicles, the probe was capable of exerting a closing force of to draw the vehicles together. This force was generated by gas pressure acting on the center piston within the probe cylinder. Piston retraction compressed the probe and interface seals and actuated the 12 automatic ring latches which