Barbecue mode created an unexpected noise problem during what should have been a serene trip. A child’s top keeps a steady spin, in part, because it is perfectly balanced around its centerline. But if you filled the top with ever-changing fluid levels, and astronauts moving within it, the top would not maintain its spinning axis. It would wobble. The Apollo guidance computer fought this effect, firing Henry Pohl’s little thrusters to keep things spinning perfectly around the original centerline. Engineers prefer a tidy system after all. The thrusters fired in brief bursts, registering each time as a loud bang inside and making sleep nearly impossible for the astronauts. (Eventually, some physicist types within NASA convinced the engineering types that it was harmless to let the craft “find its own axis” during barbecue mode—Apollo didn’t need to maintain a flawless spin, and future astronauts got some rest.)32
Engineers monitoring the flight recall a magical Houston moment for the outbound trip that December. As with my father’s earlier, math-choked research paper, Apollo employed a patchwork path to the Moon. For most of the trip, NASA referenced the craft’s position to the center of Earth, but once the Moon had more of a gravitational say, engineers switched to a new, lunar-based referencing scheme. This time, the engineers weren’t just dealing with equations; now a slip-up could lose three lives. “The onboard computer for the command module would do this big switch, would recalculate everything and switch to a lunar-centered coordinate system,” Apollo computer guru Jack Garman said. Having recently turned twenty-four years old, Garman oversaw a Mission Control console for Apollo 8 with some other young colleagues. A small indicator was supposed to light up when Apollo’s onboard computer made the mathematical transition from Earth-centered to Moon-centered reality. “At two o’clock in the morning or something on the way to the Moon,” Garman recalled, “you have nothing to do. Long moments of boredom waiting for something horrible to go wrong. So we were guessing the exact point at which the light would come on.” They essentially took bets, down to two-second intervals. “Yes, we’re a little nuts, but what do you do?”
When the indicator silently popped on, they forgot the bet. “We all stared at it and said, ‘My god. Do you know what we just saw?’ ” Human beings, for the first time, now depended more on some other rock’s influence than Earth’s. Life from Earth had really traveled to a whole different world, as honored by a little, silent bulb.33
Other staff monitored blinking lights just to make sure they kept blinking. Engineers babysitting the massive computers running Mission Control recall the tell-tale sign of computer failure. As they watched the banks of red lights, interspersed with a few greens, they knew a machine had gone belly up when all its lights went on together or all went off together. Since computer freezes were far from rare, NASA maintained three identical IBM computers, constantly updated with mission data, ready to run Mission Control. Engineers ranked computer performance based on how often they failed. During a mission, standings for the most reliable machine could update as frequently as three times per day, and the engineers could swap out which computer ran Mission Control without affecting the mission.34
As the Moon loomed ever larger in the windows of spinning Apollo, engineers encountered a new problem. The simulators had left something out, more sociological than technical. “What we didn’t do, even later, we never put any [time] delays in,” Hughes said. “It’s the first time humans had to really deal with the speed of light as a problem.” Radio waves, just like visible light, microwaves, and their many spectral relatives, move nearly two hundred thousand miles per second through space. For life on Earth, everything is close enough that we don’t usually notice any signal delays. But, once we consider the scale of the solar system, even the sunlight on your skin took a little over eight minutes of transit time to reach Earth. “There was only a second-and-a-half delay [of radio transmissions] to the Moon, which meant three seconds of total delay time. We chose not to simulate that, and we screwed up all over in the real world.” The resulting trouble for Apollo? Awkwardness. “We were always talking over each other,” Hughes said, “because humans just hate silence.” When Houston was done speaking and sending an important message to the spacecraft, they had to wait three seconds before the earliest possible response from astronauts. (Count off three seconds. A person hearing a phone silence that long today would assume the line is dead or that their conversation partner is surfing the web.) For Apollo, as Houston started talking again, they spoke right over the delayed reply from the astronauts. Then the astronauts, after a delay, would start hearing more speech from Houston that had no relation to what the astronauts had most recently spoken.
The solution that evolved for future missions primarily relied on patience with the three-second round-trip delay, but also on a simple verbal tag dating to World War II. Astronauts and Mission Control engineers began saying “over” at the end of their statements, so their far-away partners knew it was safe to start replying. In later Apollo missions, there were extra complications when the lander separated from the other modules. While Houston still suffered a three-second delay for speaking with either craft, each craft could speak to its sibling almost instantaneously. The modules were like two kids jabbering away while sleepy parents, in another room, were slow to understand.
The communications delay becomes a significant psychological problem when considering more far-flung missions. Frank Hughes still tinkers in this area, sometimes giving conference presentations on human considerations for long-term space travel. “As you get further away, the delay increases,” he said. “Mars is twenty minutes, but imagine talking to your husband with a twenty-minute delay . . . pretty soon you ask a list of questions and then get a list of answers . . . . It comes down to a really emotionless kind of thing. You say ‘I love you,’ and throw that in the wind.”35
Apollo 8 did debut a new and more comfortable sort of space communication. Counterintuitively, it marked the first manned space mission with days of uninterrupted radio contact between Earth and the astronauts. The missions in Earth orbit had flitted from one communication station to the next, frequently passing through minutes of radio silence in between. On the way to the Moon, with greater separation, Earth now always had a station facing Apollo. For Moon missions, NASA had fourteen powerful radio stations in play but primarily relied on its three largest radio stations, spacing the globe in 120-degree increments: stations near Goldstone, California; Canberra, Australia; and Fresnedillas de la Oliva, Spain. One of these would always be facing an Apollo spacecraft during its outbound or inbound journeys. The tricky hours in between, however, were a different matter.36
For Apollo 8, the most nerve-wracking communications issue was a complete radio black-out as its path slid behind the Moon. At the closest initial approach, the linked modules skimmed just seventy-five miles above a cratered orb measuring over two thousand miles across. If the Moon were a baseball, Apollo eased around it just by the width of a peppercorn. Many Apollo astronauts spoke of the Moon looming larger and larger, and wondering in the backs of their minds if something might be wrong with the calculations. Soon, they could barely see the edges of this enormous, colorless object. Their instincts told them it was too close and that they would surely collide. (My father tells a story of one Apollo astronaut, on a later mission, who couldn’t resist this natural animal response and manually rocketed his ship further away from the Moon, just to make sure.)
The mission planners had calculated an initial path that, in the case of an accident or disaster, including a possibly unconscious crew, would sling the spacecraft back toward Earth. However, with all systems functioning and the crew fully awake, Apollo 8 sought a stable lunar orbit. To exit the automatic “free return” path home, the mission had to alter its route on the far side of the Moon, when it was completely out of touch with Earth. The spacecraft burned its service module engine for four long minutes, slowing down and (fingers crossed) entering a new path that repetitively circled the Moon.37
; The waiting period on Earth, with the tiny spacecraft hidden by the Moon, would become a hallmark for the Apollo missions. In 1968, humans were for the first time completely out of sight and unreachable from all of Earth. While the engine firing lasted just four minutes, the spacecraft itself was out of touch for about an hour. Those most responsible for computing trajectories—affectionately called “luna-tics” by their colleagues, suffered these blacked-out minutes the most, saying the wait felt endless. Whenever Apollo emerged from the back side of the Moon, the precise timing would tell engineers what they needed to know. If it was exactly on time, then Apollo had found the correct, safe orbit. If it was late, they were moving too slowly and risked being yanked to the Moon’s surface. And if it was early, the craft was moving too fast and risked whipping off to distant regions of the solar system with too little fuel to come home.
On-board, astronauts trained the first human eyes on the far side of the Moon. Luckily, only one of the little windows had fogged over from outgassing sealants. What they saw was remarkable for its savagery. Compared to the near side, the far side looked more weary and pock-marked, but this heavier cratering made sense. With one side locked to face Earth a long time ago, that face—the one we know well—enjoyed modest protection from further asteroid impacts. Meanwhile, its backside remained permanently exposed to whatever the inner solar system dished out. The astronauts would have to wait to share their observations with Mission Control.
In Houston, hundreds of nervous engineers watched the mission timer as seconds oozed past. “I never will forget how quiet that whole room was,” said flight director Gerry Griffin of the fifty-plus minutes. “Hardly anyone moved that entire time.” It looked more and more certain that the ship wouldn’t emerge early, but would it be late? Then the radio signal arrived, within a fraction of a second of perfection. Engineers had aimed for an initial lunar orbit of elliptical shape with its low point 60 miles above the Moon and its high point 170 miles above the Moon; Apollo 8 entered an actual orbit of 60.5 miles on the low side and 169.1 miles on the high side, well within a stunning single percent of the calculated goal. In the software laboratory near MIT, engineers broke into ecstatic cheers. Apollo’s on-board computer had handled the maneuver, with little corrective input from Earth.38
A reporter recalled the moment from Houston.vi As he monitored the Mission Control center, “Suddenly the familiar map of the Earth vanished from the big plastic screen.” This had been the norm for the last decade, with all space missions orbiting our home planet. But now, in its place, and with no fanfare, a practical map of the Moon dropped down. “The effect was overwhelming.” The reporter, a former war correspondent, said it was one of the most memorable “heart-stoppers” of his career.39
After a couple of extra adjustments, the ship entered a more circular orbit and started collecting information on the Moon’s uneven gravitational pull. “Your orbit almost wiggled around the moon rather than a circular orbit,” engineer Hal Beck said.40 The mission completed ten orbits of the Moon in about twenty hours. Astronauts noted how much more slowly they moved above the Moon than when orbiting Earth, and this followed from basic physics and weaker gravity.
On Christmas Eve, the Apollo mission sent a formal broadcast to Earth, where an estimated one fourth of humanity huddled near a radio or television to hear a message from the Moon. The mission had already sent back the incredible “earthrise” photograph of our tiny blue planet, peeking above the lunar horizon and suggesting a reset perspective for our species. It showed a fragile orb in a largely inhospitable dark cosmos. No conflicts or boundaries or protests or gunshots could be seen from the Moon. No person looking at this photograph could deny that all people (except for three astronauts) were in it together.
The broadcast gave most of NASA a surprise. Before the launch, lead astronaut Frank Borman had wondered what he could possibly say, from the Moon, that would rise to the singular moment. He had appealed to some friends for help. One of them recalls staying up, long into the night, skimming books, trying to figure out something to recommend to the astronauts.vii He eventually started leafing through the Bible’s New Testament. His wife walked by, checking on him, and said he might want to try the Old Testament. And so, on December 24, 1968, Earth took a break from a confusing and turbulent year to hear astronauts reading the Christian origin story of the planet Earth. Each astronaut read a few verses, with William Anders starting with “In the beginning,” and finally Borman concluding with God naming “the dry land Earth.”
Another of Borman’s earthbound friends was traveling at the time. “That night in the airport lounge, as the astronauts read from Genesis, there wasn’t a single word spoken. Not one. I’m not sure that would be the case today.” He lamented that the moment’s magic could not be bottled and treasured. “Things sort of lose their currency, after about twenty or thirty years, because the up-and-coming generation has no capacity to understand it.” And despite the peaceful phrasings and the calm voice crackling from a quarter-million miles away, many on Earth still felt a ghostly tension. “When they did that reading,” the friend recalled,viii “they still had to make the burn to get back home to Earth. We didn’t know for sure if they’d make it back or not.”41
For weeks ahead of time, media coverage had included a morbid fascination with the next crucial step. Apollo coming home meant rocketing away from the Moon’s pull. To do this, astronauts would restart the single engine on the service module. The engine had no back up, and if it failed, the crew would be marooned circling the Moon, slowly running out of air. But most of the systems within the engine had back-up systems. As one engineer who worked on it said, “There were a heck of a lot of ways to start that engine.” And yet, now that the engine was so far away, with three lives attached, “It was darn scary.”42 The engine restarted without so much as clearing its throat, and Apollo 8 headed home.
Of all space’s dangers, from the extreme temperatures to the ever-present pull of the voracious vacuum, Apollo engineers also had to plan for solar flares: the sun’s infrequent ejections of radiation (and gobs of high-energy ions) that could give astronauts a hazardous zap. Solar flares could erupt with little warning, and the fastest components would hit Apollo in eight minutes, but engineers had plotted a strategy. The plan had two parts. If possible, stay in orbit around the Moon, since its bulk would protect the astronauts for half of each orbit. Then, turn the service module toward the sun, providing the astronauts additional shielding from the nasty radiation and particle streams. Apollo 8 encountered no flares, and nearly returned home without incident.
The lone hiccup involved Apollo’s on-board computer. As with many computer errors, this one followed a user’s mistaken keystrokes. For the return to Earth, the crew worried about perfecting their precise angle of attack for the atmosphere. They were moving faster than any previously re-entering ship, and the command module was also larger and heavier than the earlier capsules. But one astronaut mistyped a command and erased all basic navigational data. Instead of making a minor correction to their trajectory, he had ordered the computer to prepare for launch, as if it sat on the pad in Florida. So, following orders, the computer lost its basic notion of up from down, and the crew scrambled to the windows, trying to locate their guide stars. A cloud of urine crystals, flying alongside like so many little geese, made the starscape illegible.
Luckily, engineers in Mission Control had most of the two-plus-day trip home to diagnose the problem and talk the astronauts through re-aligning the computer. In building the system, some engineers had originally wanted to have more warnings for possible “operator errors,” such as today’s “Are you sure you want to delete this?” message, but the Neolithic machine was already pushed to the limit of its small memory and modest processing power. (A later version incorporated a kind of “undo” option for the astronauts.)43
As the mission approached Earth, the onboard computer correctly aligned the capsule and they entered the atmosphere at the appropriate three-d
egree angle (where zero degrees would be skimming across the atmosphere’s ceiling on a tangent line). Like previous capsules, the Apollo command module obeyed Faget’s original idea, facing its wide bottom forward, with the astronauts on their backs and facing the heavens. As this capsule slowed from its record speed, the braking acceleration pulled the astronauts back into their seats with seven times the force of gravity. Each of them suddenly gained the weight of an adult sea lion on their human bones. One astronaut became alarmed when he saw fist-sized glowing “blobs” flying past the windows. Was the heat shield losing that much material? But each tiny bit of heat shield that flew off (as the ablative material was designed to do) now became a burst of glowing plasma at their incredible speed—beautiful pyrotechnics but no cause for alarm this time.
The violence of re-entry and the accompanying plasma meant the command module went into communications blackout for the first time since it emerged from behind the Moon. Engineers sweated the last three dangerous minutes of a long mission. Underneath all their excitement in preparing and then monitoring Apollo 8, Frank Hughes recalls a special human gravity surrounding a mission full of unknown territory, including unprecedented distances and speeds. He’d gotten to know some of the astronauts in the simulators and in star chart training. Before that December launch, astronaut Bill Anders had asked Hughes if he would make sure his wife got home safely to their home near Clear Lake, come what may. Frank had promised he would. “It was so solemn,” Hughes said later. “It was like you’re making these last will and testament kind of moves.”
The Apollo Chronicles Page 24