No substitute for plain incompetence.
And SamAdams, I too am beginning to believe Wayne Green and others that the whole thing is a put on show because the scientists found no one could surive outside the Van Allen belts due to the high energy particles and radiation.That's why it has been nothing but robots since.
The van Allen Belts were the problem. They collect and concentrate charged particles. Solar activity was closely monitored for the moon flights and they tried to time things so there wasn't an active solar storm aimed at earth but the phase of the moon was right for the mission.