By the summer of 1968, a sense of deep unease had engulfed the American republic. Early in the year, the Tet Offensive smashed any lingering illusions of a quick victory in the increasingly bloody Vietnam conflict. Race relations boiled over in April when a single rifle bullet took the life of Martin Luther King, Jr. Two months later, as Bobby Kennedy walked through a hotel kitchen, he was shot in the head. The red, white, and blue threads that had bound America for nearly two centuries were faded and fraying.

Amid this national turmoil, senior planners at the country’s space agency were also having a difficult year. Late that summer they quietly faced their most consequential decision to date. If NASA was going to meet the challenge laid out by President John F. Kennedy, its astronauts would soon have to take an unprecedented leap by leaving low-Earth orbit and entering the gravity well of another world—the Moon. Should they do it?

Such a bold step could provide a glimmer of hope to a fractured nation. It would cement America’s lead in the “Space Race” against the Soviet Union and remind Americans of their potential for greatness on the world stage. But a romp around the Moon also carried tremendous risks. If NASA failed, its Moon dreams would expire. The agency might, too. NASA had already lost three astronauts during a launch pad fire in early 1967. Neither the public—nor Congress—would accept three more dead astronauts.

NASA decided to proceed. Because of the risks, the agency devised the mission that would become known as Apollo 8 largely in secret, with code names and subterfuge. It would only be the space agency’s second human launch since the Apollo 1 fire, and humans had not yet flown into orbit atop the massive Saturn V rocket required for the mission. If the astronauts reached lunar orbit, their Apollo spacecraft would periodically pass behind the Moon and lose contact with Earth. And if the spacecraft’s big engine failed, the crew would die in perpetual orbit around the Moon, trapped in a tiny metal tomb 240,000 miles away from all they knew and loved.

No one understood this better than Chris Kraft, the director of flight operations at NASA’s Manned Spacecraft Center (which would eventually be renamed to its current moniker, the Johnson Space Center). Kraft, who had been with NASA since its beginning a decade earlier, had gained a reputation for telling it straight. So when Susan Borman learned that her husband Frank had been selected to command the Apollo 8 mission, she went to Kraft to get it straight. Was Frank coming back this time?

She understood that before humans would land on the Moon, pioneering crews would have to fly around it. She knew someone would have to take that first jump beyond Earth. Still, she feared that her husband might pay the ultimate price for doing so. The couple had married at the age of 22, after Frank had spontaneously proposed at the side of the road. Now, nearly two decades later, they had two teenage sons. Apollo 8, Frank had promised his wife, would be his last spaceflight.

When Susan Borman asked Kraft, the veteran flight director, how he really felt about the ride around the Moon, Kraft did not dissemble. Frank Borman, he said, had a 50/50 chance of coming home safely.

Schedule problems

In the summer of 1968, NASA had not flown an astronaut into space for nearly two years, since the end of the Gemini space program. So before Frank Borman could command a mission to the Moon, NASA first wanted to get safely into orbit again following the Apollo 1 fire.

The investigation into that fatal launch pad fire raised all manner of issues with the crew capsule, and the updated Block II spacecraft redesign incorporated more than a thousand changes and improvements. The return-to-flight mission for the space agency would therefore involve taking the new and improved command module into low-Earth orbit for a shakedown mission, staying (relatively) close to home should anything go wrong. This flight became known as Apollo 7.

Originally, NASA had planned to fly the Apollo 8 mission in low-Earth orbit, too, bringing the delicate lunar module into space for the first time. Nothing like the spidery lunar lander had ever been built before. It would operate only in the vacuum of space and therefore needed no heavy shielding. Consisting of a descent stage that would fly down to the lunar surface and a smaller ascent stage that would blast back off the surface, the combined vehicle weighed about 15 tons, two-thirds of which was propellant.

The lunar module’s weight was problematic right to the very end of its design cycle. It requires considerable energy—in this case, rocket fuel—to launch mass to low Earth orbit and then nearly as much again to go from there to the surface of the Moon. NASA offered the lander’s contractor, Grumman, $50,000 for every pound safely removed from the vehicle. As a result, the lunar lander’s walls were only about as thick as three sheets of aluminum foil.

“It was a machine that was built to save weight,” Kraft said in an interview. “It had to have the lightest materials possible, and therefore it was fragile. That’s the only way I can describe it.”

According to NASA lore, recounted in Apollo: The Race to the Moon, a technician working with a test version of the vehicle absentmindedly clicked the cap of his ballpoint pen against a filled fuel tank. This minute amount of pressure opened a small leak in the tank, and the thin stream of propellant sliced off his finger with surgical precision. That fragile.

After the inevitable delays that come from inventing an entirely new type of spacecraft, Grumman finally delivered the first lunar module to Cape Canaveral in the summer of 1968. Almost immediately, technicians and engineers found it to be even more delicate than they had feared. The silk-like wiring inside would break easily. Critical systems did not work. Despite NASA’s hopes for flying the lunar module before the end of 1968, the vehicle was not space-worthy. Any significant delay to get the lunar lander into shape would disrupt the entire Apollo mission timeline, potentially pushing the first landing into the 1970s.

Throughout the spring and summer of 1968, George Low, the manager of the Apollo spacecraft program, fretted about the lunar module and pondered scheduling flights in the run-out to the lunar landing. With the post-fire changes to the command module, Low felt like the capsule was coming together. It would get a good test in October of that year with the Apollo 7 flight. The Saturn V rocket had flown twice at this point, and instead of flying the lunar module, Low wondered what he might do instead with just the command module and his massive rocket.

By late summer, he had his answer.

“My lord, that’s a big step.”

On one of those sultry, unbearably humid Houston days in August, Low called Kraft into his office at the Manned Spacecraft Center in Houston. They walked together to meet with Robert Gilruth, who had masterfully led the Space Task Group at the founding of NASA and overseen the fledgling agency’s efforts to put a human into space. Revered by his peers, Gilruth now managed the Houston spaceflight center. In Gilruth’s office, Low outlined his plan to bypass the lunar module test missions for now and use the Saturn V rocket to send the Apollo 8 spacecraft around the Moon.

Kraft recalls Low asking him and Gilruth, “Do you think we could do that?” They responded with muted caution, the Apollo 1 fire tragedy still fresh in their minds. They knew, too, that preparations for the Moon were still evolving. The Apollo program had been scrambling to develop software for lunar flights, and engineers were having all sorts of problems with the simulators. Kraft and Gilruth also worried about the extra risk of adding a lunar flyby to the first crewed Saturn V launch. Either activity alone carried a significant amount of risk; together, the risk was far higher. They wanted some time to think it over.

Kraft returned to his office and gathered some of his people. He wanted to do it—the idea of pulling off such a mission and gaining a huge and visible advantage over the Soviets stirred his patriot’s soul—but Kraft was not sure mission operations could pull something like this off in such a short time. To keep the Apollo program on schedule, this mission had to launch during the last 10 days of December. NASA would only have about 16 weeks to plan and execute a lunar flyby. After Kraft told his team about the plan, he asked them to think about it overnight.

“The next morning I got to the office at about 7 o’clock and my phone was ringing off the hook,” Kraft recalled. “I’d gotten messages as early as 5 o’clock in the morning.” His engineers had thought about it—and they could do it. They relished the challenge. Moreover, they didn’t just want to fly around the Moon—they wanted to go into orbit around Earth’s pale companion.

This was a bold suggestion stacked on top of a bold suggestion. It would have been far simpler to rocket out to the Moon on a “free return trajectory,” which essentially would see the Apollo spacecraft slingshot around the Moon and then be flung by the Moon’s gravity right back toward Earth without the crew having to do anything. On such a path, even if the spacecraft’s main engine failed, simple physics would ensure the capsule made a safe return back to the planet. But going into orbit was different. It required the command module’s mighty service propulsion system engine to fire precisely in order to put the spacecraft into orbit. More critically still, the engine had to fire again so that the crew could head back home.

Kraft’s engineers had good reasons for assuming additional risk, however. Two years earlier, in order to study the world and better identify landing sites, NASA had begun launching robotic spacecraft to orbit the Moon. As they traveled above the dusty, gray surface, these spacecraft would drift thousands of meters away from where they were predicted to be. In 1968, scientists had realized there were places on the lunar surface with much higher and lower concentrations of mass. This caused gravitational imbalances that had been tugging spacecraft out of their prescribed orbits.

If the command module could make several orbits around the Moon, these engineers realized, astronauts could map out some of these mass concentrations, providing a huge boost to trajectory calculations for future lunar missions. During an orbital flight, astronauts could also take high-resolution photographs of the lunar surface to help scientists pinpoint safe landing sites for later Apollo missions. It made sense to Kraft, but he had to convince Low and Gilruth—who in turn would have to convince the agency’s managers in Washington, DC.

“They had the same reaction I did,” Kraft said. “‘My lord, that’s a big step.’ I told them, yes it is a big step, but eventually we’re going to have to do this. Eventually we’re going to have to figure out the gravitational models if we’re going to land on the Moon. We’re going to have to have that information in the lunar module computer.”

Ruminating on the Apollo 8 mission nearly half a century later, Kraft recounted the discussions that followed. Some key figures, such as Saturn V rocket designer Werner von Braun, immediately embraced the idea. Others feared that NASA couldn’t pull it off and that another accident might kill the Moon program. Eventually everyone, including President Lyndon B. Johnson, signed off.

“That’s how we got to Apollo 8,” Kraft said. “It sounds simple now.”

The 16-week sprint to the Moon began.

Space race heats up

If Low, Gilruth, Kraft, and other managers entertained doubts about flying Apollo 8 to the Moon during the fall of 1968, they soon had another incentive to press ahead. After falling behind NASA’s Gemini program, the Soviet Union was preparing to make a last-gasp effort to win the race to the Moon. And it seemed entirely possible that they might win.

On September 14, a modified version of the new Soyuz spacecraft launched from Baikonur, Kazakhstan aboard a powerful Proton rocket. The mission, Zond 5, carried a small menagerie to the Moon, including two tortoises, mealworms, wine flies, and a few other living things. During its circumlunar flight, Zond 5 came within 2,000km of the lunar surface. The Soviets had succeeded in sending animals into orbit a decade earlier and beat America to the Moon’s orbit with a similar cargo.

Fortunately for NASA’s efforts to snoop on the competition, the Soviet spacecraft’s braking system failed on the way back to Earth. Instead of making a secretive landing on the steppes of Kazakhstan, Zond 5 splashed into the Indian Ocean. As part of Cold War-era spy games, the USS McMorris, a destroyer escort, had been shadowing two Soviet recovery ships there. They all converged on the landing zone, and sailors aboard the McMorris took pictures as the Soviets recovered the capsule and its bewildered—but live—menagerie.

This intelligence confronted NASA with the very real possibility that the Russians were still working to reach the Moon and might have a viable plan to send humans there before NASA. There were, after all, several rapidly approaching launch windows the Soviets could use.

This was a bitter pill to swallow. During the Gemini program in 1965 and 1966, NASA had superseded Soviet achievements in space with extended spacewalks and delicate docking maneuvers. America had the more sophisticated space program—and yet the Soviets had just sent a few creatures around the Moon. Certainly, humans might fly in the next Zond capsule.

Even if the Soviets didn’t land on the lunar surface, images of beaming cosmonauts returning from the far side of the Moon would allow the Russians to claim victory. This prospect would keep more than a few NASA engineers up at night during the fall and early winter of 1968.

Admiral McCain

Because of the orbital dynamics involved, a Moon mission in December would have to take flight during the last 10 days of the month. For NASA, spending Christmas at the Moon would only enhance the holiday. But to complete its space missions, NASA also relied on help from other parts of the government, particularly the US Navy.

For Apollo 8, the capsule would splash down in the Pacific Ocean just two days after Christmas. However, US sailors had already received orders to stand down for the holidays. The ships NASA needed to recover its astronauts would not be stationed at sea but would be docked in Pearl Harbor. Someone would have to go and ask—beg, really—the Navy to break up the shore leave of thousands of sailors and their commanding officers.

In late November, it fell to Kraft to fly out to Honolulu to meet with the commander-in-chief of the Pacific Fleet, John S. McCain, Jr. At the time, Admiral McCain’s son, the future senator from Arizona, had just entered his second year of captivity in Vietnam. Kraft hoped that the prospect of a successful lunar mission would lift the admiral’s mood along with the rest of the country.

In Hawaii, Kraft found himself at the front of an amphitheater-style conference room, filled with about 100 captains and admirals, with McCain himself sitting in the middle of the front row, assiduously smoking a long cigar. The NASA flight director laid out the agency’s plans for the mission and how it would showcase US greatness in space. Then Kraft got down to the point. Ships would be needed at sea from before the launch through Christmas. Without the Navy’s help, the communists might win the Space Race.

McCain’s initial response was silence. Then, Kraft recalls, the admiral stood up and threw his cigar down on a table. Even today, Kraft beams at the memory of this meeting: “He said, ‘That’s the best goddamn briefing I’ve ever heard, give this young man anything he wants.’”

NASA was going to the Moon.

Best Christmas ever

One of the reasons for McCain’s willingness to call back his sailors may have been the growing national unease. By November, the country had endured a bruising presidential election, exacerbating national fault lines, and ending with Richard Nixon as president of a riven America.

Civil rights problems simmered on, too. North American Aviation was building the Apollo Block II capsules at its Downey facility in California. The factory was just a few miles from Watts, which in 1965 had been the site of massive race riots, widespread looting, and arson after reports of police brutality ignited the public. Thirty-four people had died.

“I was certainly in tune with what was going on in the country at the time,” recalled Chester Vaughan, who headed up the NASA team developing the capsule’s reaction control thrusters. “We were a little bit isolated from it, but not totally, because when we traveled out to the LA area there was a lot of bad stuff going on there. It was very visible to us. We’d be very careful about which roads we would take.”

As they worked on the mission, finalizing the Apollo spacecraft for humanity’s first voyage into deep space, the 400,000 men and women involved in the program knew they straddled a fine line between triumph and tragedy.

“Luck is important,” Vaughan recalled. “We don’t count on it. We do everything we can to be sure we don’t need to be lucky, but boy when we work out and we are in fact lucky, that’s also good.”

So when Vaughan and the rest of the space program watched as Apollo 8 lifted off on its monstrous Saturn V rocket, they felt little elation. The hard stuff lay ahead. The first major test came three hours later, when the crew broke out of low-Earth orbit. Until then, no human had ever ventured more than 850 miles from home, the altitude reached by the Gemini 11 mission. Less than two minutes after burning their engines for the Moon, Frank Borman, Jim Lovell, and Bill Anders had eclipsed that mark, and, as Tom Hanks so famously said in Ron Howard’s Apollo 13, put Sir Isaac Newton in the driver’s seat.

Fortunately, the Apollo spacecraft worked almost without flaw during its two-and-a-half-day cruise out to the Moon. Every time the crew needed the spacecraft’s engine to make a precise burn, it responded. Crew members even had time for two television broadcasts to celebrate the flight’s historicity.

On the morning of Christmas Eve, the Apollo capsule slipped into orbit around the Moon. The crew had 20 hours there, and they took more than 700 photos of the bleak lunar surface during multiple orbits. Anders also captured the Earthrise photo, probably the most historic photo ever taken by an astronaut, as humanity’s cradle emerged above the lunar horizon.

During their penultimate orbit, at about 9:30pm ET on Christmas Eve, the crew made its third television broadcast. With an estimated one billion people watching, each astronaut described observing the Moon fly past them 110km away. Here was another world, just outside their windows. “The vast loneliness up here of the Moon is awe-inspiring,” Lovell said.

After this, Anders said the crew had a message for everyone watching, and each man proceeded to read a section of Genesis. For an engineer like Vaughan, who had given a decade of his life to building spacecraft for this very purpose, watching humans fly around the Moon for the first time overwhelmed him. Then the Genesis reading began. At first, Vaughan didn’t understand what they were reading in the audio-only broadcast. But then he got it.

“I had goosebumps all over,” he said. “When those guys signed off on that clip it was just, hey man, this is the best Christmas ever.”

A Santa Claus

Meanwhile, flight controller Rod Loe sat at his console in Mission Control during the crew’s Christmas Eve surprise. He had bent over his flight log as the reading progressed, hoping none of his fellow workers would notice the tears welling in his eyes.

The young flight controller had grown up just down Interstate 10 from Houston in Beaumont, Texas, and graduated as an engineer from the local college in 1961. Such were the opportunities for young engineers that, less than four years later, Loe found himself within the beating heart of the space race.

During the Gemini missions, from his EECOM position, Loe monitored communications with the spacecraft and its electrical and environmental systems. By the time the Apollo program began in 1967, the kid from Beaumont had become one of NASA’s more seasoned flight controllers, and he already found himself being groomed for more senior positions.

Loe had been among the first flight controllers told about NASA’s audacious plan to fly around the Moon for Apollo 8. He recalled hearing about the change when his branch chief, Arnie Aldrich, grabbed him for a meeting in Kraft’s office. Frank Borman, the mission’s commander, was there, along with a handful of other flight controllers. Kraft asked if anyone knew of a reason why the flight couldn’t be done.

“I remember nobody could come up with a good one off the top of our head,” Loe recalled. “Chris said go think about it.”

After that meeting, Loe told Aldrich he would accede to whatever management role his future held as long as he could remain on console, as an EECOM, during Apollo 8. For Loe, going into lunar orbit, flying the command module around the Moon, represented the pinnacle of the Apollo program.

“That was where we did our thing,” he said. “That was our design mission to go up and orbit the Moon. For us that was a biggie. That was the biggie.”

Loe got his wish, with a front-row seat for the Christmas Eve reading. Yet Mission Control could spare little time for emotions, as the flight’s most critical moment came about four hours after the Apollo 8 crew made its Christmas Eve broadcast. On the back side of the Moon, with no way to communicate, Borman had to fire the spacecraft’s powerful engine for a little more than two minutes, increasing the capsule’s velocity by more than 2,400mph. This acceleration would break the command module out of lunar orbit and put it on a trajectory back toward Earth.

The SPS engine was the most reliable engine humans could devise, and with the exception of the thrust chamber and nozzle, every component had at least one redundant twin. It was effectively two completely separate engines that shared a common thrust chamber. However, for all its internal redundancy, the SPS engine itself was a single point of failure with absolutely no backup. If it failed to fire, or if it didn’t provide enough change in velocity, or if the computer shut the engine down early, the spacecraft would remain in orbit around the Moon and the crew would die. The engine had to work.

During this blackout phase, at about 1am on Christmas Day in Houston, Loe described the mood inside Mission Control as quiet, apprehensive, and nervous. At one point, when some chatter picked up, Kraft barked, “Could you please shut up over there?” Later, Kraft repeated himself again. The silence continued, more or less, for another 15 minutes until the spacecraft was due to appear from behind the Moon.

“Houston, Apollo 8, over,” Lovell, the command module pilot, radioed down to Mission Control. After an acknowledgement from Ken Mattingly in Mission Control, Lovell had another special message from the crew for a worldwide audience. “Please be informed there IS a Santa Claus,” Lovell said.

The spacecraft came barreling around the curve of the Moon exactly on schedule. All the math had been right, and all the hardware had worked. It was an incredible public validation of years of effort. Mission Control erupted in cheers.

“Proud to be Americans”

The danger had not yet ended, however. No humans had ever returned through Earth’s atmosphere at 24,700mph, the velocity at which Apollo 8 came tearing back from the Moon. Even so, Loe said, he felt like he could relax just a little bit after the crew had put themselves on their return trajectory. Two days later, the astronauts splashed down in the Pacific Ocean. Among other Navy vessels that Kraft had secured over the holidays, the USS Yorktown aircraft carrier was on the scene. A helicopter lifted the men, one by one, from the spacecraft and flew them to the carrier, where a red carpet awaited.

The crew was safe. Finally, Mission Control broke into an extended celebration with their customary cigars. For Loe and the other flight controllers, the party moved to the Flintlock Inn on NASA Road 1. Today, the road is a six-lane elevated highway, and the inn is gone, replaced by a miniature golf amusement park. But during those simpler times, the road was just four lanes, and cars crowded the median as the inn’s parking lot overflowed. Mission Control worked hard, and after a successful flight, it partied hard.

As the festivities roared to life, Loe recalled that he and one of Mission Control’s legendary operators, John Aaron, didn’t go inside right away to join the tumult. Instead, they stood outside the Flintlock, watching cars go by. The war, the protests, and the assassinations had clouded the future of the country. But this mission had brought some joy into the world and allayed some of the doubts about America.

When one of the Apollo 8 flight directors, Milt Windler, asked why they weren’t upstairs, Loe had an answer. “We’re just standing here, proud to be Americans,” he said.

It was hard not to be proud. Nearly a third of all living human beings had just watched the event. Even televisions in the Soviet Union carried the broadcast. Kraft, Vaughan, Loe, and 400,000 others engaged in the Apollo program had beaten the Soviets. And yet, at this moment, it seemed that Apollo had transcended even the Cold War.

Upon reaching the Moon, humans found something unexpected; the astronauts were not enthralled so much by the stark lunar surface as by their new perspective on home. During the Christmas Eve broadcast, Lovell tried to express what it felt like to watch the Moon fly by, saying, “It makes you realize just what you have back there on Earth.”

Listing image by NASA / Aurich Lawson

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