b'Engineer Innovation | The Digital TwinApollo Command Module Mission Simulator showing Apollo 13 prime crew member Ken Mattingly in training. Mattingly was bumped from the crew a few days before launch because of exposure to the measles. Image credit: NASAcontrol, all that you can hear is calmthe crew and mission control these reasoned decision making in the face ofinclude Go, No-go decisions at critical a terrible and potentially tragicstages of the spaceflight, and how unfolding situation. decisions would be made in a crisis.This is because of the flight controllers,The various simulators were controlled by and the Apollo 13 crew, were well- a network of digital computers, up to ten rehearsed through simulation. Beforeof them, which could be networked launch, simulators were used to define,together to simulate a single large test, and refine mission rules, theproblem. There were four computers for instructions that determined the actionsthe command module simulator, and of mission controllers and astronauts inthree for the lunar module simulator. The critical mission situations. Among thecomputers could communicate using 256 many simulators, the command modulekilobytes words of common memory, simulators and lunar module simulatorswhere information needed throughout occupied 80 percent of the Apollothe simulation could be stored. training time of 29,967 hours. There are at least two examples of Flight director, Gene Kranzs, Whitesimulated scenarios that directly Mission Control Team (one of three) hadinfluenced the successful resolution of 11 days of simulation training to prepareproblems on the actual missions for the landing of Apollo 11, seven of(although there are likely hundreds those with the actual crew, and four withmore).simulated astronauts. As well as training both teams, the purpose of the sessionsIn the final simulation of the Apollo 11 was to define a set of mission rules thatmission, controllers wrongly aborted would define any actions taken by bothduring the final stages of lunar landing 12'