Apollo was a three-part spacecraft that consisted of a command module, service module and a lunar module. The command module or the CM contained the crew’s quarters and the flight control section.
It contained all the necessary commands and instruments to operate the spacecraft and to return to the Earth. The CM was in fact the only part that returned to the Earth and the astronauts were provided with reclining couches, specially fitted for them.
The Apollo spacecraft’s service module or the SM carried the rocket engine that could be started or stopped whenever needed. The SM held the spacecraft’s electrical power system. It also contained the fuel. The third part known as the lunar module, or the LM, took the crew to the surface of the Moon. This module also provided the astronauts with the necessary support on the Moon and returned them to the command module.
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