Apollo experience report: The docking system

The decision to accomplish the lunar landing mission by use of the lunar orbit rendezvous technique required that a docking system be developed to allow: (1) spacecraft modules to be structurally joined, (2) intravehicular transfer of the crew and equipment, and (3) separation of the modules. The basic design criteria of the docking system, the evolution process, and the various docking concepts considered for the Apollo program are presented. Docking systems that were considered for the Apollo program included both impact and nonimpact systems; a probe and drogue impact system was selected. Physical and functional descriptions of the probe and drogue, the crew transfer tunnel, and docking ring latches are presented for both the early configuration and the present configuration as influenced by the development and qualification test programs. In addition, preflight checkout activity and mission performance of the system are discussed.