Apollo 10 flew everything except the last fifteen kilometres. In May 1969 Tom Stafford, John Young and Gene Cernan took the full lunar landing profile to the Moon and rehearsed all of it — the transit, the orbit, the undocking, the descent — and then, by design, stopped short of the surface and came home. It was the most tantalising assignment in the history of flight, and the crew were entirely clear-eyed about it: they were there so that the next crew could land.
The call signs said it all. The command module was Charlie Brown and the lunar module was Snoopy, the beagle sent ahead to sniff out the ground, and Peanuts characters became unofficial mascots of the whole programme. Stafford and Cernan took Snoopy down to about 15.6 kilometres above the Sea of Tranquility, close enough to make out boulders in the intended landing zone and to report that the site looked, in Cernan's phrase, smooth as a baby's bottom.
There is a persistent story that NASA short-fuelled the ascent stage so the crew could not be tempted to land. Cernan always insisted the propellant load was simply what the flight plan required, and the arithmetic supports him — but the tale endures because everyone understood the temptation was real.
Then Snoopy tried to kill them. As the crew staged the ascent module, the abort guidance system was left in the wrong mode and the spacecraft began hunting wildly for a command module it could no longer find, rolling and pitching through the sky. Cernan's startled expletive went out live to millions of listeners on an open loop — an unfiltered eight seconds that generated letters of complaint and, in hindsight, the most human moment of the mission. Stafford took manual control and steadied the vehicle within seconds.
Coming home they set a record that still stands: at nearly 39,900 kilometres per hour, no human beings have ever travelled faster than the crew of Apollo 10. Snoopy's ascent stage was sent off into orbit around the Sun, where it presumably still is — the only lunar module to survive intact anywhere. Eight weeks later Armstrong and Aldrin flew the same profile all the way down.
