Although the contractors had shipped excellent spacecrafts, preparations at Kennedy did not go quickly from the assembly building to the launch pad. Testing was delayed several days in order to stay out of the way of Apollo 9 pre-flight activities. Also during maintenance to the Launch Control Center, the electrical power was switched off to replace a valve. The Apollo 10 launch vehicle’s pneumatic controls sensed the power outage, opened some valves and dumped 20,000 liters of fuel on the launch pad.
“Some of those guys came in figuring, “I’ll write my textbooks and my thesis and teach [university courses] and I’ll come by twice a week and be an astronaut.” Well, that didn’t work …. We were devoting our lives to this whole thing, and you couldn’t devote anything less, I don’t care what your discipline was.”
With Group 4, for the first time, the selection criteria did not include a requirement for test pilot proficiency. Selectees who were not qualified pilots would be assigned to the Air Force for a year of flight training. The primary scientific requirement was a doctorate in medicine, engineering, or one of the natural sciences.