Data flow and voice between the spacecraft and Mission Control
The Communication, Command and Telemetry System (CCATS) was the heart of a communication system between the spacecraft and the flight controllers. CCATS was connected to an elaborate world-wide network of tracking stations, stations to maintain data and voice communication with the spacecraft and communication relay satellites. CCATS had three UNIVAC 494 mainframe computers for data processing one as the Mission Operational Computer (MOC), a second as a Dynamic Standby (DSC) and a third UNIVAC 494 as a reserve available for other tasks.
The Real Time Computer Complex (RTCC) was used to transform data from CCATS into data suitable to display on the various console screens used by the flight controllers. The RTCC was also used to calculate and plot flight trajectories and to prepare data and commands to be uploaded to the spacecraft's on-board computer via CCATS. With five IBM 360 mainframes the RTCC had more computer redundancy than CCATS with its three UNIVACs 494.
In this diagram is shown how CCATS and RTCC could be configured in such a way that both centers can support an ongoing mission and support the training of flight controllers for the next mission at the same time. There were two Mission Operations Control Rooms (MOCRs) available to enable mission support and training simultaneously.
A system named ASCATS (Apollo Simulation Checkout And Training System) was used to simulate an Apollo mission. ASCATS was not part of the Mission Control Center, it was residing in another building at the Johnson Space Center.
The data generated by ASCATS to simulate data from launch vehicle, spacecraft and remote sites were indistinguishable from real mission data. With ASCATS data could be generated to simulate all kinds of malfunctions to train the crew, prepare them for various eventualities and to validate procedures. ASCATS could be configured in various ways for training the crew of the Mission Control Center, for training the astronauts and for training the crew at various remote sited. In a so called integrated simulation all groups were involved.