Forty years ago, this week, a pair of astronauts, one imbued with a delightful country-boy drawl and the other with an intense dry wit, bounced across the Moon’s surface at a mountainous place called the Cayley Plains, about 50 km south of the crater Descartes. Every so often, the joyful whoops of Charlie Duke could be heard over the radio, followed, inevitably, by a one-line quip from his commander, John Young. For two men who almost didn’t land on the Moon at all – and, after landing, managed to ruin an important heat-flow experiment and found that the nature of the site was quite different from what had been expected – Apollo 16 was shaping up to be a remarkable success. However, 22 April 1972, the day of Young and Duke’s second EVA, began with disappointing news: the heat-flow experiment was beyond repair. A pre-mission change to its electrical connector meant that its power cable had probably been sheared and although repair tests on the ground were successful, it was ultimately decided that fixing it would consume too much of Young and Duke’s time, which was already dictated virtually to the minute.
Departing the lunar module Orion in the rover that morning, the astronauts’ first destination was Stone Mountain, to the south-east of the landing site, which formed a stunning backdrop. They parked in a small crater, halfway up the mountainside, and were able to view the local terrain from an elevation of a couple of hundred metres, higher than any previous Apollo crew. Young and Duke were rewarded with an astonishing view of South Ray Crater – an enormous bowl-like depression, five times the size of a football pitch – which radiated ‘rays’ of boulders, some dark, others bright, in a myriad directions. In the months before launch, Young had pushed strongly to add a fourth EVA to the mission and mount an expedition into the crater itself, but radar soundings from Earth suggested that there were too many boulders for the rover to negotiate safely. Now, looking down into South Ray, John Young could see that those predictions had been overestimated.
Still, the evidence for whatever had created South Ray was all around them…and this was unfortunate, because the very purpose of visiting Stone Mountain was to obtain samples of material thrown up by the Descartes crater impact. With the slopes thus ‘polluted’ by material ejected by the South Ray impact, it would be difficult to unambiguously identify the soils and rocks for which they sought. A brief sampling stop at a quintet of craters, known as ‘the Cincos’, was followed by a bumpy drive, back down the mountainside to another bowl-like depression, where Young set to work with a rake to gather samples. Nothing of volcanic origin was found. By the time the second EVA ended, after more than seven hours outside, there had been few ‘eureka’ moments, but the geologists on Earth were well pleased with the astronauts’ efforts.
Simply being on the Moon, even for this irreverent pair, was astounding. Several months before launch, during a geological trip to Hawaii, Charlie Duke had a strange dream – a haunting, through not nightmarish dream, which he would later recount for an Al Reinert film, For All Mankind. Whilst in Hawaii, he came down with flu and ran a high fever; at times he was almost delirious. In his dream, Duke and Young were on the Moon, driving the rover up to the north. “It was untouched,” he said. “The serenity of it had a kind of a pristine purity about it.” They continued to bounce across this endless landscape until, startled, they came upon a set of tracks in the ancient dust, which they promptly followed. After an hour or so, they came to a vehicle. It looked just like the rover, with two people inside, who looked just like the two astronauts. They had been there for thousands of years.
Relating this dream, Duke was adamant that he never felt fear on the Moon and it was often easy to lose sight of the reality that beyond the few layers of his space suit was a near-total vacuum. “If you spring a leak in that suit,” he said, “you’re gonna be dead!” Anything intrinsically hostile about the Moon faded when he beheld its awesome beauty; the hills were rounded, quite at odds with the angular, malevolent-looking mountains of sci-fi lore. In the glare of the harsh lunar morning, surrounded by such lifelessness, Duke felt that he was supposed to be there. “We did not feel like we were intruders,” he wrote on his website, www.charliedukestory.com, “in this foreign, foreign land.”
Now, on 23 April 1972, at the start of their third and final EVA, Duke and Young headed for North Ray Crater and the dream entered his consciousness once again. As they drove in the rover, Duke took photographs and described the terrain, whilst Young negotiated the potholes, bumps and hollows of the surface. Duke was also the navigator, keeping tabs on the maps and the geology stops and the headings that they were supposed to follow. “As John started off,” he told the NASA oral historian, “I said ‘Okay, John, steer 120 degrees for 1.2 km and then turn left to 090 degrees and go another 2 km’. That’s the way we navigated.” Magnetic compasses were useless on the Moon and the rover carried its own directional gyroscope and an odometer which clicked off their distance in kilometres. With their own tracks to follow, there was never any risk of getting lost, but the distance the rover could travel was always dictated by the demands of the so-called ‘walkback limit’. If the rover conked out, they could never be too far from Orion to walk back if necessary.
By 11:30 am EST, they reached the south-eastern rim of North Ray. The crater was more than a kilometre across and even the rover’s television camera, remotely controlled from Earth by engineer Ed Fendell, could not fit its entirety into the field of view. Nonetheless, mission controllers gaped in astonishment, for North Ray’s precipitous walls plunged 200 m from the rim to its rock-strewn floor. Before launch, Young had advanced the idea of taking a 30 m tether with them, so that one man could descend partway into the crater’s gaping maw, anchored by his colleague. Ultimately, weight constraints and nervous managers nixed the idea. Young and Duke lingered at North Ray for a few minutes, taking panoramic photographs and gathering and documenting rock and soil samples. One rock which drew mission controllers’ attention was a large, dark boulder on the crater’s eastern rim. Was it from the deepest part of the excavated crater, they wondered? Moreover, could it be evidence for the long-sought volcanism of the Cayley region?
Watched by the rover’s television camera, Duke dashed across to the boulder, followed shortly by Young.
“It may be further away than we think,” warned Young.
“Nah, it’s not very far,” replied Duke.
“Theoretically, huh?” deadpanned Young. “Like everything else around here: A couple of weeks later…” Beneath Young’s humour lay an inherent difficulty of judging distance and perceiving depth on a world with no sensible atmosphere and no landmarks, such as trees or telegraph poles, by which to gain one’s bearings. In Mission Control, there was amazement as Duke seemed to get smaller and smaller in the television view. By the time he finally reached the rock, the geologists realised that the ‘boulder’ was much bigger than originally believed. In fact, the astronauts dubbed it ‘House Rock’.
“We kept jogging and jogging,” Duke recounted, “and the rock kept getting bigger and bigger and we were going slightly downhill, that we didn’t sense it at first.” When they reached it, House Rock towered above them. Duke estimated its size at maybe 25 m across and 12 m high. Rather than ‘collecting’ it, they resorted to their geology hammers to chip away a few specimens, then headed back uphill to the rover.
Operating in their bulky space suits required far more strength and stamina than Duke had anticipated. Unlike the garments worn by the earlier Apollo astronauts, including Armstrong and Aldrin, the later ‘J-series’ suits were modified to permit easier bending at the waist, but it was still a constant battle. Picking things up with the stiff gloves, Duke related, was like squeezing a hard rubber ball for hours and hours, constantly. More than one Moonwalker has compared operating in the suit to a ‘light workout’…albeit a continuous one, for six or seven hours! The suits’ hardiness was also balanced by their fragility. At one stage, the astronauts staged their own lunar Olympics – to commemorate that year’s event in Munich – and Duke fell over backwards, followed a high jump…and landed directly on his life-sustaining backpack. For a few moments, his heart literally raced. Was the plumbing damaged? For a few moments, Duke’s childlike excitement vanished.
“I got real quiet,” he recalled, “and you could hear the pumps running in the backpack. I checked my pressure. It was okay. This fear began to subside.”
The following day, 24 April, after a smooth ascent into lunar orbit and docking with crewmate Ken Mattingly in the command module Casper, the astronauts were on their way home. Due to the earlier problem with the service module’s engine, original plans to remain in orbit for 24 hours to gather remote-sensing data were cancelled. During his three days alone, circling the Moon, Mattingly had been hard at work with a package of eight experiments, known as the Scientific Instrument Module bay (SIMbay), housed inside the service module. Radiation measurements, laser altimetry, mass spectroscopy and terrain imaging and mapping to a resolution of just 2 m was undertaken. A subsatellite was ejected to measure particle abundances and magnetic fields, although its orbit was far from ideal and it hit the Moon a few weeks later.
From his lonely perch, with Berlioz’ Symphonie Fantastique playing in the background, Mattingly could think of no better place to be than lunar orbit…with one exception: the chance to actually go down there and plant his own bootprints in lunar soil. In his mind, the only way to top his experience on Apollo 16 would be a landing. “But you wouldn’t want to skip the lunar orbit part,” he cautioned to the NASA oral historian, “to go to the surface. You need both, because the lunar orbit piece, especially solo, was probably more sense of exhilaration. It was really, really something!”
This exhilaration reached its zenith on 25 April, when Mattingly performed a trans-Earth EVA, venturing outside to retrieve camera film cassettes from the SIMbay. Ordinarily, command module pilots did not perform EVAs, and thus their helmets were not fitted with gold-tinted Sun visors, so Mattingly went outside wearing in John Young’s red-striped helmet. He spent 84 minutes outside, in the cislunar void, collecting not only the cassettes, but also setting up a package of microbial specimens for ten minutes in Orion’s open hatch. He retrieved it before he returned inside. For a few nervous moments, Mattingly thought that he had lost his wedding ring. He had only gotten married, to Elizabeth, a couple of years earlier, and feared that it had floated outside, lost forever.
From his vantage point, Mattingly was surrounded by an ethereal blackness, quite unlike any of the EVAs performed in Earth orbit or on the Moon. The absence of stars and the twin views of a crescent Earth and the Moon itself – just 80,000 km away – startled him. When he reached the end of the service module, he anchored himself in a pair of foot restraints and, for the first time, the enormity of where he was hit him. But there was little time. Grabbing the cassettes, and aware of the steadily dwindling oxygen supply, he headed back toward Orion’s open hatch. Seconds before returning inside, his attention was arrested by Duke’s shout: “Look at that!” In the blackness, Mattingly saw a glint of something moving. It was his missing wedding ring, just about to float outside. He grabbed it and shoved it into a pocket. Doubtless, his wife was relieved.
A few days later, on 27 April 1972, the command module Orion splashed down in the mid-Pacific. Apollo 16 had destroyed many presumptions about the nature of Cayley Plain and the Descartes region and forced a radical rethink as to their geological origins. None of the rocks and soils directly ruled out volcanism, elsewhere in the lunar highlands, Andrew Chaikin cautioned in his book A Man on the Moon, but almost certainly none had occurred in the region where John Young and Charlie Duke walked. The intrinsic problem, Chaikin explained, was that too many geologists had paid too much attention to the close physical resemblance of the lunar highlands to terrestrial volcanic features.
Still, the overflowing scientific harvest from Apollo 16 demonstrated a key maxim: that science advances most when its predictions are proven wrong. The astronauts – all military pilots by training – had shown themselves to be astute field geologists, but the call had long since risen from the scientific community for one of its own to fly aboard the final landing mission, Apollo 17, scheduled for December 1972. By the time Young, Mattingly and Duke splashed down, the final lunar crew had already been training for eight months. Commanded by veteran astronaut Gene Cernan, it included Ron Evans as pilot of the command module…and professional geologist Dr Jack Schmitt as part of the landing team. If the penultimate lunar mission had whetted scientists’ appetite, then Apollo 17 would be their final opportunity of the 20th century to unlock more of the Moon’s mysteries.Missions » Apollo »