Four hours after a bone-jarring launch from Cape Kennedy—marking the first-ever space mission to originate from Pad 39B—and an equally rattling ride through Trans-Lunar Injection (TLI), on 18 May 1969 the crew of Apollo 10 were finally on their way to the Moon. Their mission to lunar orbit would clear the final hurdles before humanity’s first piloted landing on an alien world on Apollo 11. Those hurdles included Commander Tom Stafford and Lunar Module Pilot (LMP) Gene Cernan guiding the spider-like Lunar Module (LM), which they had nicknamed “Snoopy”, to within nine miles (15 km) of the Moon’s surface. In doing so, they left Command Module Pilot (CMP) John Young to become the first man ever to fly solo in orbit around the Moon.
As outlined in last weekend’s AmericaSpace history article and the first instalment of this four-part feature, Apollo 10 was a fundamentally critical stepping-stone in evaluating the tools, techniques and technologies needed to bring humans down to the lunar surface.
Shortly before 4 p.m. EDT on 18 May, Young executed his first major task of the mission by pulling Apollo 10’s Command and Service Module (CSM), dubbed “Charlie Brown”, away from the spent final stage of the mammoth Saturn V rocket. He smoothly rotated the craft by 180 degrees in a “transposition and docking” maneuver to collect Snoopy. By now, in the mysterious void between Earth and the Moon—known as “cislunar space”—the view of the Home Planet had changed significantly. In the hours after launch, it resembled a gigantic map, unfolded beneath” them, but now, as they headed toward the Moon, it had shrunk noticeably, from filling Charlie Brown’s windows to something the size of a basketball. By the time they reached lunar orbit, it appeared little bigger than a marble. “For the first and only time in my spaceflights,” Stafford later wrote in his autobiography, We Have Capture, “I felt strange.” They were a long way from home.
For Cernan, a man born and raised in the Catholic faith, yet by his own admission “not an overly religious person”, it redefined everything he thought he knew; out here, the smallness of Earth, its continents, and even its vast ocean trenches were dwarfed by the true infinity of the Universe. This beautiful, perfect, limitless expanse of nothingness must, he reasoned, prove the reality of some form of Creator, but to comprehend the matter further went beyond his mortal understanding. “Someone, some being, some power, placed our little world, our Sun and our Moon where they are in the dark void,” Cernan pondered, “and the scheme defies any attempt at logic.”
These thoughts were undoubtedly with all three men at quiet times throughout their voyage, but such were the demands of a lunar expedition that no one had the opportunity to dwell upon them. Notions of infinity came figuratively back to Earth by the grind of daily life aboard ship. Achieving the late President John F. Kennedy’s challenge was on everyone’s mind. None of the astronauts wanted to screw up, get sick or miss a step in the timeline. Sickness was a major concern. All three men had experienced stuffy heads upon arriving in space, although the sensations cleared within a few hours for both Stafford and Young. For Cernan, it lingered a little longer, but by 20 May he felt fine.
It was a little ironic that Apollo 10 was the first American flight in which bread—real bread—officially became part of the crew’s pantry. “Officially”, that is, because some years earlier one member of Stafford’s crew was reprimanded for taking a corned-beef sandwich into space. On the Gemini 3 mission, John Young arranged for the treat to be sneaked aboard as a surprise for his crewmate, Virgil “Gus” Grissom. Unfortunately, after taking a bite, Grissom had been obliged to put it away when it started to crumble and bits began to float around the cabin. This problem was solved in time for Apollo 10: slices of white and rye bread were flushed with nitrogen, which kept them fresh for up to two weeks and prevented them from drying out and crumbling into fragments.
Drinking, on the other hand, gave Tom Stafford a rather unpleasant surprise when he forgot to open a valve to the ship’s water tank and was rewarded with an evil-tasting dose of highly chlorinated water. There were other problems, too. The drinking water was a by-product of the hydrogen-oxygen fuel cells, which generated Charlie Brown’s electricity, and on previous missions astronauts had complained about the presence of hydrogen bubbles in it. A new drinking bag was created, with a handle that enabled the astronauts to whirl it around and separate the gas from the water. Unfortunately, it did not work and caused the hydrogen bubbles to settle at the bottom, then remixed with the water when they took a sip. All three astronauts suffered what NASA euphemistically referred to as “gas pains”, but they avoided an outbreak of diarrhoea.
Maybe the quality of the drinking water affected the men’s appetites, which remained low throughout the mission. To be fair, the food was by no means haute cuisine: even Don Arabian, head of the Apollo Test Division—who once described himself as “a human garbage can”—struggled to find anything appealing in the tasteless sausage patties and minuscule chicken bits. Early in May, he volunteered to try Apollo 10’s fayre for four days, but after three days of chewing food with a taste like granulated rubber, he understandably lost the will to live! Some foods were better than others, of course, and some could even be eaten quite “normally” with a spoon; but the dehydrated dishes needed reconstituting with water and that meant injecting an uncomfortable amount of hydrogen gas into their meals. Not surprisingly, the men ate little during their mission to the Moon.
Still, with Snoopy attached to Charlie Brown’s nose, Apollo 10 provided a relatively large space in which to live and work. For Tom Stafford, whose two previous Gemini missions had been like sitting in the front seat of a Volkswagen Beetle, it felt almost like having an attic or an extra apartment. The job of opening up that apartment fell to Gene Cernan, who floated through the tunnel early on 19 May, to be greeted by a snowstorm of floating fiberglass crumbs! It turned out that a Mylar cover on the command module’s tunnel wall had torn loose, releasing the cloud of snowy particles, which itched like hell, took hours to vacuum up, stuck to hair, eyebrows, and lashes, and left Cernan looking “like a hound dog who’d been in a chicken coop”.
By the following morning, Apollo 10 was more than 150,000 miles (240,000 km) from Earth and its velocity had slowed to a relatively puny 2,480 mph (4,000 km/h), as the gravitational influence of the Home Planet waned. Shortly thereafter, it entered the Moon’s sphere of gravitational influence and began to accelerate as it “fell” toward its objective. “Our trajectory,” wrote Stafford, “had been so accurate that three of our four mid-course correction burns had been cancelled.” The only mid-course burn of Charlie Brown’s large Service Propulsion System (SPS) engine changed their velocity by barely 33 mph (54 km/h). It was so accurate that the last two burns were canceled. This also served to calibrate the engine for the forthcoming entry into lunar orbit.
Eight and a half thousand miles (14,000 km) from the Moon, they made a television transmission, giving their audience another view of Earth, which by this point had diminished to somewhere between a grapefruit and an orange. Such views gave Stafford a chance to jab at the British Flat Earth Society that “the Earth is round”. Perhaps the use of the word “round”, rather than “spherical”, pre-empted the society president’s defiant response: “Colonel Stafford, it may be round, but it’s still flat, like a disk!” Yet the television camera was a marvel and gave the eager audience an unprecedented sense of “being there”. By the end of the flight, Apollo 10 made 19 telecasts, spanning almost six hours and providing such a novel dimension for what was happening in space that Stafford, Young and Cernan received a special Emmy award. The resolution was so good that when they filmed the transposition and docking with Snoopy, viewers could actually count the tiny metal rivets on the lunar module’s skin. “Finally,” wrote Cernan, “the taxpayer would get a look at where their money was going.”
If the taxpayer knew where their money was going, it was not until Apollo 10 passed around the limb of the Moon late on the afternoon of 21 May that the astronauts finally saw where they were going. Until then, their goal had been virtually invisible. “During the entire mission,” wrote Stafford, “we had been facing its night-time side, which was almost totally black. Peering through his navigation equipment, John Young had been able to find a place in the sky where the stars were occluded, so we were pretty sure the Moon was out there.” The trajectory planners and mathematicians had guided them to the Moon with pinpoint accuracy and there it was, the lunar surface, just 60 miles (95 km) from them; so close, it seemed, that they could almost touch it.
A few minutes before five in the evening, the SPS engine slowed Apollo 10 by 3,660 mph (5,900 km/h) and inserted it into an elliptical orbit. “I pitched the spacecraft over,” wrote Tom Stafford, “so we could get a good view of the surface. We were looking at the so-called far side of the Moon, the tide-locked side facing away from Earth.” Visible in sharp relief were forbidding mountains, pockmarked ridges and furrows, and thousands of craters—including the gigantic Tsiolkovsky basin, named after the humble Russian schoolmaster today revered as the father of theoretical cosmonautics. Indeed, the lunar far side looked so tortured that it reminded Stafford of a plaster-of-Paris cast.
On the near side, the dark, basalt-rich Sea of Crises was easy to spot, a flat-floored, wrinkle-edged blob, clearly visible to the astronauts in the wonderful, eerie clarity of the early lunar morning. It really stood out, said Young. Stafford added that the ridges running across its floor went “straight down just like the Canyon Diablo in New Mexico”. Originally given the Latin name “seas” (mare) by early astronomers—who mistook their darkness for being open water—the lunar mare were actually formed by ancient volcanic eruptions, many of which (as a result of the samples collected by astronauts on the Moon) have been dated to between three and four billion years old. Their intrinsic darkness comes from their iron-richness and some two dozen maria on both the near and far sides cover around 16 percent of the lunar surface.
Two orbits after their arrival, a second SPS burn roughly circularized Apollo 10’s path around the Moon at an altitude of a little more than 69 miles (110 km). As the astronauts gawped through Charlie Brown’s windows, their eyes adapted to distinguish finer gradations of color in this lifeless world. It was now early morning, lunar time, and the surface exuded a vivid spectrum from white to black and a mix of greys, tans, sickly pale yellows, and hints of red in some craters. The spectacle was completed by the awe-inspiring sight of their first Earthrise on the lunar horizon; even at this distance—some 240,000 miles (370,000 km) from home—they could still pick out the ice caps, the vast bulk of Antarctica, the southward-projecting finger of Baja California, the intense flecks of white cloud, and the iridescent blues of the oceans.
Moving into their third orbit around the Moon, Stafford, Young and Cernan again broke out the camera and treated their audience to the first-ever televised images of Earth’s closest celestial neighbor in color. Although these early images were somewhat “washed-out”, thanks to the height of the Sun in the sky, they improved as Apollo 10 headed westward, where the illumination was oblique and the terrain was brought into sharper relief. Capcom Joe Engle in Mission Control described the vast expanse of the Sea of Fertility as “unbelievable”. Other controllers were dumbstruck by the Langrenus impact crater, its walls up to two miles (3.2 km) high in places, its central, cone-like peak rising 3,200 feet (1,000 meters) from an irregular, boulder-strewn floor that Apollo 8 astronaut Jim Lovell, the previous December, had described simply as “huge”.
Stafford keyed his mike: “Houston, tell the world we have arrived!”