Apollo Command/Service Module

The Command/Service Module (CSM) was one of two spacecraft, along with the Lunar Module, used for the United States Apollo program which landed astronauts on the Moon. It was built for NASA by North American Aviation. It was launched by itself on three suborbital and low Earth orbit Apollo test missions using the Saturn IB launch vehicle. It was also launched twelve times on the larger Saturn V launch vehicle, both by itself and with the Lunar Module. It made a total of nine manned flights to the Moon aboard the Saturn V.After the Apollo lunar program, the CSM saw manned service as a crew shuttle for the Skylab program, and the Apollo-Soyuz Test Project in which an American crew rendezvoused and docked with a Soviet Soyuz spacecraft in Earth orbit.The CSM consisted of two segments: the Command Module, a cabin that housed a crew of three and equipment needed for re-entry and splashdown; and a Service Module that provided propulsion, electrical power and storage for various consumables required during a mission. The Service Module was cast off and allowed to burn up in the atmosphere before the Command Module re-entered and brought the crew home.The CSM was initially designed to return all three astronauts from the lunar surface on a direct-descent mission which would not use a separate Lunar Module, and thus had no provisions for docking with another spacecraft. This, plus other required design changes led to the decision to design two versions of the CSM: Block I was to be used for unmanned missions and a single manned Earth orbit flight (Apollo 1), while the more advanced Block II was designed for use with the Lunar Module. The Apollo 1 flight was cancelled after a cabin fire killed the entire crew and destroyed the Command Module during a launch rehearsal test. Corrections of the problems which caused the fire were applied to the Block II spacecraft, which was used for all manned missions.