As the lunar module approached, Young saw it through his sextant at a distance of 259 kilometers. Stafford and Cernan got a radar lock on the command module shortly after the insertion burn and watched with interest as the instrument measured the dwindling gap between the vehicles and demonstrated the theories of orbital mechanics in actual practice. Cernan especially liked the steady communications that kept both crews aware of what was happening.
On May 18th 1969, a king, some congressmen, other distinguished guests, and a hundred thousand other watchers waited at scattered vantage points around the Cape area. At 49 minutes past noon, Rocco Petrone’s launch team sent Apollo 10 on its way to the United States’s second manned rendezvous with the moon.
John Young enjoyed the longest career of any astronaut thus far. Over the course of 42 years of active NASA service he made six space flights and is the only person to have piloted, and been commander of, four different classes of spacecraft: Gemini, the Apollo Command/Service Module, the Apollo Lunar Module, and the Space Shuttle.
On Cernan’s second space flight, he was lunar module pilot of Apollo 10, May 18-26, 1969. Apollo 10 was the first comprehensive lunar-orbital qualification and verification flight test of an Apollo lunar module. Cernan was accompanied on the 248,000 nautical sojourn to the moon by Thomas P. Stafford (spacecraft commander) and John W. Young (command module pilot).
Apollo 10 crew briefed on emergency egress slide at pad 39-B