The three main components of the Apollo spacecraft were the command module, service module, and lunar module. The command module or CM was the primary crew quarters and to re-enter Earth’s atmosphere after the mission had been completed. The CM also contained the primary guidance, navigation, and control system. The CM design did not undergo many changes throughout the Apollo program. The service module of SM contained the bulk of the fuel and oxygen supply for the entire spacecraft as well as the environmental control unit (ECU), the SM was unpressurized and was jettisoned right before re-entry. The lunar module or LM was designed after Apollo 1 so I will not go into great detail about it. Apollo 1 was designed with the Saturn IB which could launch a partially fueled SM or the LM. Apollo 1 was internally designated as mission AS-204 and construction began on the CM in August 1964 and the CM and SM were connected September 1966. (Nasa.gov-Apollo 204) During the combined system checks many malfunctions were noted and corrected and some work was deferred to a later date. …show more content…
On October 27, 1966 the ECU was removed and brought back to the factory for a design change, around the same time a propellant leak developed in the SM and it would require the CM and SM to be separated for repairs. When altitude chamber tests recommenced a leak was found in the water/glycol system on the ECU so it was removed and repaired again. Early spacecraft used a pure oxygen environment for the crew, a nitrogen-oxygen mix was considered but many pilots complained of the “bends” they felt when exposed to it. During the last manned altitude chamber test the capsule was pressurized to 58.8 psi pure oxygen for 6 hours and 15 minutes, the crew expressed satisfaction with the performance of the spacecraft. The CM and SM were then moved from the altitude chamber to the launch vehicle at Complex 34