CM stands for command module, the primary crew cabin and control center of a spacecraft. It houses the life support systems, flight instruments, and communication gear required to fly the mission. During reentry, it is usually the only section of the vehicle designed to survive the heat and safely return the crew to Earth.
Heard on the job
We need to verify the CM life support telemetry before initiating the undocking sequence.
Insider tip
In the Apollo program, the CM was paired with the Service Module to form the CSM.