A module of a spacecraft occupied by the crew, who operate the main controls located there. It normally refers to the conical command modules of the Apollo missions. They were each 3.9 m in diameter at the widest point and 3.5 m high, a spacious compartment compared to the earlier Mercury capsules. The command module was launched sitting above the service module, and the two remained connected in space to comprise the command and service modules (CSM).