Command/Service Module is one of the two spacecraft that were utilized for the Apollo program, along with the Lunar Module, to land astronauts to the Moon.
The Command Module together with the Lunar Module, are oftenly called the Apollo spacecraft. The spacecraft consists of two segments, the command module, housing the crew and the equipment needed for re-entry and splashdown and a service module which provide propulsion, electrical power and storage for various consumables required during a mission.
The Command Module is a truncated cone. The forward compartment contained two reaction control engines, the docking tunnel and the components of the Earth Landing System. The inner pressure vessel housed the crew accommodations, equipment bays, controls and displays and many spacecraft systems. The aft compartment contains 10 reaction control engines and their related propellant tanks, fresh water tanks and the CSM umbilical cables.
The Service Module houses the service propulsion system and its propellants, the fuel cell power system, four maneuvering thruster quads, the S-band antenna for communication with Mission Control and storage tanks for water and air. The Service Module is divided into six sectors.