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.
The UNIVAC 494's were used as communication processors and the IBM 360's as real-time data processors.
A system named ASCATS (Apollo Simulation Checkout And Training System) was used to simulate an Apollo mission.
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 sites. In a so called integrated simulation all groups were involved. ASCATS could be linked to a spacecraft trainer at JSC, building 5, or to a spacecraft trainer at KSC (Kennedy Space Center) in the FCTB (Flight Crew Training Building).
ASCATS was temporarily housed in building 422, as depited in the diagram, it had one UNIVAC 494, one IBM 360-75 and peripheral equipment. The UNIVAC 494 was used as the Apollo Process Control Unit (APCU) and the IBM 360-75 as the Ground Support Simulation Computer (GSSC).
The GSSC was able to generate data to act as a simulator for remote sites, for the spacecraft trainer, for MCC and for all three entities at the same time in an integrated simulation. ASCAT was controlled from the Apollo Simulation Control Area (ASCA). From ASCA faults could be inserted into the data streams to create simulated error conditions or simulated system malfunctions for training purposes.
ASCATS also contains a facility, Apollo Simulated Remote Site (ASRS), to train remote site personnel.
ASCATS was moved to the MCC in 1969. Its UNIVAC 494 and the IBM 360-75 computers were disposed of because one of the five computers of the RTCC and one of the three computers of the CCATS could be made available for training sessions.
The Goddard Space Flight Center, in Greenbelt, Maryland, was the hub of the Manned Space Flight Network (MSFN), a worldwide network of tracking stations.