Command and Service Module

The Command and Service Module (CSM) is one of two components of NASA's Apollo spacecraft. It is used to carry the astronauts and the second spacecraft, the Lunar Excursion Module (LEM), from Earth's to lunar orbit, and bring the astronauts back home. It is designed for 3 crew members, of which one would stay in the CSM in orbit while the other two go down to the Moon's surface with the LEM.

The CSM consists of two parts, the Command Module (CM) and the Service Module (SM). The Command Module is the cabin that houses the crew and equipment used for the mission. The Service Module provides propulsion and electric power and has also additional storage for all kind of consumables needed for the mission.

After the flight back to Earth, the two parts are seperated just before entering Earth's atmosphere. While the Service Module will burn in the atmosphere, the Comand Module will bring back the astronauts to Earth's surface, protected by its heat shields and slowed down by parachutes before splashing into the ocean, where it is recovered by ground crew.