Capsule communicator

Spacecraft communicator (CAPCOM)

Generally, only the spacecraft communicator communicates directly with the crew of a crewed space flight. The acronym dates back to Project Mercury when the spacecraft was originally termed a "capsule." NASA felt it important for all communication with the astronauts in space to pass through a single individual in the Mission Control Center. That role was first designated the capsule communicator or CAPCOM and was filled by another astronaut, often one of the backup- or support-crew members. NASA believes that an astronaut is most able to understand the situation in the spacecraft and pass information in the clearest way.