Five decades ago, this week, Americans could almost taste the Moon, as the days drew closer to landing a human on its dusty surfaceand honoring a national pledge from the late President John F. Kennedy. Already, in December 1968—on only the second manned flight of the Apollo spacecraft—U.S. astronauts had triumphantly voyaged to lunar orbit and in May 1969 efforts were well underway to test the Command and Service Module (CSM) and Lunar Module (LM) around the Moon for the first time.
Apollo 10, crewed by Commander Tom Stafford, Command Module Pilot (CMP) John Young and Lunar Module Pilot (LMP) Gene Cernan, would be nothing less than a full dress rehearsal for the first manned landing on another world. And aboard their LM, Stafford and Cernan would approach the lunar surface and draw as close as nine miles (15 km). By the time Apollo 10 returned to Earth, a significant hurdle in enabling American boots on the Moon was gone.
Over the years, questions have been raised, and raised again, as to why Apollo 10 could not simply have been changed to a full-blown lunar landing. The word to stress here is “simply”; for taking such an audacious step was by no means simple. Early in 1969, NASA associate administrator George Mueller hinted strongly that Apollo 10 might land on the Moon, but Tom Stafford was decidedly unhappy about the prospect. “Tom was not so adamant about being first on the Moon,” wrote Cernan in his autobiography, The Last Man on the Moon. “He never looked at it that way. He wanted to do what was the best thing to do and have a co-ordinated, planned program.” Rather than endorsing Mueller’s suggestion, Stafford replied that if Apollo 10 was rescoped to do a lunar landing, then he—Stafford—would most certainly not be aboard the mission! There were simply too many unknowns, and too much work still to be done, before the final step could be taken.
The main problem was that LM-4, the lunar module assigned to Apollo 10, was overweight; it had always been earmarked for either an Earth-orbital or lunar-orbital test flight and as such had not been subjected to the Super Weight Improvement Program by prime contractor Grumman. However, the LM-5 lunar module was light enough to handle a landing, but to use it on Apollo 10 would necessitate a couple months’ delay. “When you added up what we would gain, as opposed to what we would lose,” explained Deke Slayton in his memoir, Deke, co-authored with spaceflight historian Michael Cassutt, “the decision was pretty easy.”
Stafford, Young and Cernan were assigned to Apollo 10 in November 1968, after wrapping up backup duties on the Apollo 7 crew, and NASA initially described their mission as encompassing a range of options, “from Earth-orbital operations to a lunar-orbit flight”. When Apollo 8 successfully circumnavigated the Moon, planning for Apollo 10 similarly expanded from a simple undocking and formation-flying exercise between the CSM/LM combo to a more detailed battery of tests, reaching just nine miles (15 km) from the lunar surface, to rehearse the point at which a real landing mission would begin its Powered Descent. This would permit an all-up test of the LM’s throttleable descent engine, landing radar and rendezvous radar. Trajectory analyst Bill Tindall even proposed a “fire-in-the-hole” burn of the LM’s ascent engine at low altitude to simulate an abort. However, on this point he was overruled, as Apollo 10 was becoming steadily overloaded with tasks.
Even in the late spring of 1969, riding on the coattails of Apollo 8’s success, many wondered why Stafford, Young and Cernan could simply not take a chance: After traveling all the way to the Moon, with all the necessary hardware in place, why not land? However, others cautioned that the software and procedures needed as the LM descended in a precise, sweeping arc, under the thrust of its throttleable descent engine, had still to be verified. Two years earlier, managers decreed that half a dozen different docking modes had to be demonstrated, ahead of a landing. “So far,” wrote Deke Slayton, “we had demonstrated exactly one.” The drive to reach the Moon was already proceeding at break-neck pace and to skip another step and attempt a landing so soon was too rash to risk.
One of the lessons carried over from Apollo 9 was the need to impose individual callsigns on the CSM and LM. The choice of “Gumdrop” and “Spider” by the Apollo 9 crew went down like a lead balloon with some NASA managers, until Stafford’s men revealed their selection: “Charlie Brown” for the CSM and “Snoopy” for the LM! It was not just a bit of fun. For years, NASA had awarded “Snoopy pins” to its staff in recognition of their outstanding work. “The choice of Snoopy was a way of acknowledging the contributions of the hundreds of thousands of people who got us there,” wrote Tom Stafford in his autobiography, We Have Capture. “Once you had Snoopy, Charlie Brown couldn’t be far away.”
Originally scheduled to fly on 1 May 1969, Apollo 10 slipped until the 17th in order to best “fit” the lunar launch window. Another 24-hour delay was effected to allow Stafford and Cernan to benefit from closer levels of sunlight to those Apollo 11 would encounter when they made their low pass over Site 2, the area on the Moon’s Sea of Tranquility where the first planning landing was slated to occur. The mission would also make history as the Saturn V’s first, and only, liftoff from Pad 39B.
Training of the prime crew and their backups—Commander Gordo Cooper, CMP Donn Eisele and LMP Ed Mitchell—was feverish as launch neared. Not until he was placed into pre-flight quarantine, in early May, could Stafford finally appreciate the enormity of the mission he was about to undertake. On the evening of the 16th, the crews had dinner with Vice President Ted Agnew and James McDonnell, founder of the aerospace giant which had built NASA’s Mercury and Gemini spacecraft. Late on the following afternoon, driving a little too fast back to the Cape Kennedy crew quarters after seeing his family, Cernan was pulled over by a deputy sheriff.
An absence of papers in his car’s glovebox, an iffy-looking military driving licence which, it seemed, never expired and an unlikely-sounding name aroused the officer’s suspicions. Fortunately, a timely intervention by launch pad leader Guenter Wendt saved the day. Sharing a quiet “word” with the disbelieving cop, Wendt finally satisfied him that all was well. No, said Wendt, unfortunately “Mr. Kurnin” could not accompany the officer to the police station, because—motioning toward the distant Saturn V—he had somewhere important to go tomorrow.