Meanwhile, two sets of radar nervously chirped. The landing radar sent four beams downward toward the Moon. One beam regularly measured the distance to the Moon, but each of the other three reported the lander’s speed (relative to the surface) in three directions: forward-backward, left-right, and up-down. These three employed the same “Doppler effect” used by highway patrol officers and meteorologists to measure speeds of cars and winds. A separate radar system aimed in the other direction, away from the Moon, ideally just to track the command module when they later docked.20 The lander’s guidance computer had a lot to juggle. (In Huntsville’s U.S. Space and Rocket Center, you can try a video game version of piloting a Moon landing—I was zero for four on the easiest setting before I noticed that a line of unhappy kids waited their turns behind me.)
As von Braun rightly predicted, this first manned attempt was bound to have surprises. Astronauts had trouble keeping the lander’s antenna pointed at Earth during their careful descent. The Moon-to-Earth signal came and went, but this was merely an annoyance compared to the real problems looming.
“When one of these alarms came up, it would ring what was called the master caution and warning system,” Jack Garman said, in describing what happened next. “Like having a fire alarm go off in a closet.”
At about thirty-five thousand feet—the altitude of a commercial airliner—the astronauts reported bad news to Houston. “They get this four-digit code for what the alarm is, 1201, 1202 were the two alarms,” said Garman. (Upon his eventual retirement, his friends gave him a T-shirt featuring these fateful numbers.) In 1969, long from retirement, he surveyed his cheat sheets. “So we looked down at the list at that alarm,” he said. “And if it doesn’t reoccur too often, we’re fine.” What was the problem? The computer went through a cyclic period of calculations, repeating every two seconds. If at the end of two seconds, it hadn’t completed its laundry list, it first complained with an error code. Next, it shook itself off and restarted itself—not a restart in modern standards, with a spinning color wheel or hourglass making a user nervous, but rather a carefully designed, instant reboot. Here was an enormous benefit of a simple computer. “Flush everything, clean it out, look at those restart tables,” Garman explained. “And go back to the last known position and proceed forward.” In each cycle, engineers had the computer running through the most important tasks first, so the tasks Apollo neglected on that July day were not critical to landing. The actual cause of the overload wouldn’t be known for another day of round-the-clock, back-room work in Houston and at MIT’s Instrumentation Lab.
Recordings of these tense seconds feature a reedy voice telling mission controllers “Go flight”—no need to abort the mission, keep going for the landing. Engineers mercilessly teased this youngster with falsetto renditions of his “Go flight” for months to come. But the chain-smoking engineers remained every bit as calm as, or even calmer than, the astronauts. The high-voiced engineer, Steve Bales, chalked it up to practice. “Looking back, the sims were almost as pressure-packed as the flights,” he said. “Sometimes [they] would throw problems at us that were so hard. . . . We’d crash or abort the landing. . . . And we practiced right up until two days before the launch.”21
The alarms kept popping up, since the computer was continually overloaded with information, and Houston watched pilot Neil Armstrong’s heart rate climb to 150 beats per minute. As the lander approached the surface, the cycle time decreased as planned, because the computer sought to update itself more frequently. Now it finished even fewer of its tasks in one second, compared to two seconds, and the error code switched to “1201” versus “1202.” Again, engineers advised Mission Control to ignore it.
In the end, the press portrayed this as a “computer error” overcome by the cunning of valiant humans. But the computer was actually just following orders. The human mistake, discovered after the landing, involved leaving both radar systems on. Even as the poor lander’s brain tried to track the lunar surface below, it was also trying to find the rest of Apollo in orbit. Wouldn’t the diligent engineers have tested for this? They did. But two things differed between simulations and the first real landing. For one, the docking radar, pointing upward, was now just feeding pure noise to the computer, since the rest of Apollo was nowhere to be found. Noisy input was much more challenging for the computer than sane, simulated input; noise chewed up more processing time. Next, engineers had made one tiny, sloppy error. In the Earth-bound labs, they hooked both radar systems to the same battery supply, unwittingly creating a false digital harmony. On the actual lander, each radar had a separate source of power. Since they were not happily synchronized in space, the staccato nature of their blather made the computer work twice as hard to listen. (Imagine two friends talking to you at the same time instead of taking turns.) If anything, the great design of Apollo’s computer program—its jukebox-style “software”—saved the day. If it hadn’t been so robustly designed to restart itself and brush aside such errors, the astronauts would have been forced to abort the mission.22
The landing was tense enough, even ignoring alarms. After the noisy confusion, astronaut Armstrong spent extra minutes looking for a good spot (i.e., no boulders, no slope). Given the best photos available, NASA had chosen what looked to be as smooth as a parking lot, but the intended site, once Armstrong took in a good eyeful, was strewn with car-sized boulders. With the lander still gliding too quickly to land, about thirty miles per hour and five hundred feet high, a new problem emerged: an empty fuel tank warning.
Marlowe Cassetti provides another window into the engineers’ obsessive dedication. Cassetti, after all, had lugged a teletype home to his dining room table to make sure this day would work. “When they called out ‘low level light,’ I thought, ‘Oh, my God. I did something wrong,’ ” he said. “ ‘I didn’t take everything into consideration.’ ” It turned out this low fuel warning was largely mistaken. Cassetti now labels it a “very interesting phenomenon.” As the lander approached the Moon, it stopped braking, and physics no longer pushed the fuel against the bottom of its tank. The Moon’s relatively weak gravity allowed the fuel to slosh around much more than it would on Earth. Hence the fuel gauge was increasingly inaccurate as the craft approached its landing. “It was a cliffhanger for me,” Cassetti said. “Of course, everybody gave me hell for it. ‘Marlowe, what did you do?’ ”23
But Armstrong did find a spot, avoiding boulders and craters. As the lander set gently down, Garman snapped out of a trance. Everything had felt like just another simulation until he heard an astronaut mention that their engine was kicking up lunar soil. He later said this was the moment when the magnitude of the milestone hit him.
Frank Hughes, the simulation master, stood with a colleague in Mission Control and they found themselves surprised. “Son of a bitch,” said the coworker.
“Goddamn,” said Hughes.
He later tried to describe their mindset. “None of us thought 11 would make it, I mean, just statistically, something had to go wrong.” They didn’t necessarily mean disaster, just an aborted landing and a return to the command module. After a handshake, Hughes and his colleague got back to work. A major checkpoint awaited, just one minute after landing. If the engineers found certain problems, they would have the astronauts immediately launch back to space. Another major checkpoint would follow, ten minutes after landing.24
Simultaneously elated and worried, NASA realized it wasn’t sure exactly where the lander was. As astronauts described the local terrain viewed through their constricted windows, Mission Control tried to match those descriptions to existing lunar maps. One engineer recalled the scene as nearly comical. When they finally triangulated Apollo 11’s historic spot, it was four miles from its intended target. This rare imprecision rankled the troops.25
In the constant Earthly chatter, engineers found more reasons to avoid celebrating the milestone. To some, the lander’s angle of repose was too great. Instead of being on absolutely flat ground, it l
isted slightly. Engineers wondered if it could take off safely from such an inclined position.
Another group, monitoring data streaming back from the Moon, drew sharp inhales. Something was wrong with one of the fuel lines. Temperature and pressure readings quickly spiked, and nobody knew why. There wasn’t a lot of fuel left in that thin pipe, but when hot enough, it became unstable—they risked a deadly explosion shortly after this remarkable landing. One of the lander’s designers recalled being suddenly drenched in sweat. “Nature took over and solved the problem for us,” Tom Kelly wrote later. The line had become clogged by a chunk of frozen fuel. “Heat soaking back from the engine melted the fuel ice plug . . . and the pressure abruptly dropped to a low value. We looked at the screen in amazement for a few seconds, then broke into smiles and cheers of relief.”26
The famous moments of astronaut Neil Armstrong descending a ladder to the lunar surface provided more breathless moments for engineers. One of von Braun’s long-time German colleagues, Ernst Stuhlinger, recalled his own sense of responsibility. Early on, von Braun had charged him with divining the scientific consensus about whether or not the Moon’s surface would support a lander and human footsteps. Stuhlinger had found that, overall, most thought it would work, but some still-dissenting scientists had said astronauts might encounter deep drifts of dust. Now an astronaut slowly descended the rickety, low-weight ladder. “We held our breath,” Stuhlinger recalled. “Does he sink in or does he find solid ground?”27
Armstrong’s last step was a significant drop to the surface, looking to many like a sudden lurch. The engineer who’d developed the last-minute stowaway flag gulped. “What went through my mind was the ladder broke,” Moser said. “The sharp edge got his space suit, put a hole in the space suit, and the whole lunar program was over.” Every engineer had a horrible projection of how his or her unique mistake could ruin everything.
Astronaut and pioneer Armstrong, the first human to set boot on another terrestrial body, then made his famous statement (either misspoken or, as he later maintained, misheard), intended to be “That’s one small step for a man, and one giant leap for mankind.” But the transmitted, transcribed, and forever-quoted version, making less sense, omitted the “a” before “man.”
An enormous television audience on Earth took in these moments. Some, like Henry Pohl’s wife watching at home with their children, worried that Armstrong could fall off the Moon, or just accidentally leap off it, given the strange gravity everyone was talking about. In League City, Texas, a friend of my parents snapped our first family portrait: a beaming engineer father sitting on the floor, and his wife holding an oblivious baby, with the blurry televised image behind us.
Audiences took for granted that the televised pictures were so poor, so grainy. After all, the signal traveled all the way from the Moon. But the televised images suffered a single bad decision in the early 1960s. Originally, engineers had just planned for radio signals. In designing Apollo’s communication systems, they didn’t leave a lot of extra room (in terms of signal bandwidth) for something as complicated as a TV transmission. To their credit, it may not have been clear to your average nose-to-grindstone engineer in 1961 what television would become by 1969. Even late in the game, some were against having a TV camera aboard Apollo. It was just something else to design, another heavy object, more astronaut training, and more equipment that could fail. The compromise was a specially crafted black-and-white signal carrying just a fourth of a standard TV signal’s resolution. It also looked choppy because it updated the screen at a slower rate than normal TV. (Regular broadcasts updated screens sixty times per second, whereas the Apollo TV signal updated just twenty times per second.) In a final insult, the Moon signal wasn’t compatible with standard earthly infrastructure. Engineers had to display it on a special system built for the Moon signal; then they pointed a normal television camera at that screen. Faget, who’d been a leading voice for televising the first Moon walk—how could we not, he argued, after spending $20 billion to get there—shook his head at the “stingy”-looking result.28
Still, audiences on Earth were spellbound. An estimated 95 percent of American televisions, and a total of one in six of the world’s population, watched. Walter Cronkite had a rare moment as his eyes filled with tears. “I’m speechless,” he said.
In fact, humans never have known how to digest something so completely alien, this miraculous feat of engineering and organization. What did it mean? What could anyone say about it? Many relied on a hackneyed analogy to Columbus sailing across the Atlantic and “discovering” the Americas. But those continents were already brimming with people. These new space vessels were nothing like creaking sailing ships, and colonies would not be sprouting upon this desolate orb.
Cronkite, a long-time second place finisher in nightly ratings, would soon leapfrog his NBC competition. He rallied from his tongue-tied moment to bring the discussion back to Earth, and eventually, in filling the long airtime between updates, he poked critics of NASA. “I’d like to know what those kids who were kinda pooh-poohing this thing are saying right at this moment.” Despite this squares-versus-hippies narrative, most criticism for the Moon shot had risen from either research scientists (e.g., Apollo wasn’t designed to actually discover much) or voices, like Reverend Abernathy’s, from American social movements (e.g., space exploration seems like a foolish or even cruel way to spend money, given poverty at home).29
Even if they watched without milk and cookies, actual hippies did tune in and marvel. In one Houston backyard, a young group of radical architects and artists, including some hailing from California’s “Ant Farm” collective, built a special viewing chamber for the event. They assembled an enclosed “space egg” of black plastic persistently inflated by an electric fan. The group gathered in their tent-like egg after dropping acid, and tripped with the television flicker providing the only light within. The squeaky, scratchy radio signals of astronauts mixed with the fan’s hum. At the conclusion of the lunar transmission, the group had the brilliant-sounding idea to take the whole apparatus to the space center itself and assemble it there for all to see by morning’s light. Re-inflating the egg in a gas station parking lot, they were surprised that nobody else was there to behold it. But as NASA and most of their audience well knew, the mission was only half complete.30
The two astronauts took a busy two-hour excursion outside the lander. They reported on the mobility and temperature of their suits. Armstrong took a call from President Nixon. Fellow astronaut Buzz Aldrin literally kicked lunar dirt as part of a planned “soil mechanics” experiment. They planted the American flag, collected about fifty modest Moon rocks, scooped a few pounds’ worth of lunar soil, and—using their special Hasselblad camera—took about 150 photographs. Then they carefully climbed the ladder. Before repressurizing the thin balloon of the crew cabin, they unhooked their sustaining backpacks and, in mid-century fashion, tossed these and other depleted articles overboard as Moon litter. After closing the hatch, they settled down for a few hours of sleep before a planned launch from the surface. The lander’s main designer left Mission Control and tried to get his own sleep in a nearby hotel. “But I kept waking up and worrying about a micrometeorite strike or window failure,” Tom Kelly said, “leaving the crew gasping for breath in an airless cabin. I knew the odds were overwhelmingly against this, but that did not stop my worrying.” The astronauts probably slept better than most of the engineers in those hours.31
When it came time for liftoff, the lander left behind its lower segment, legs and all. The crucial ascent engine worked like a champ, and the slight tilt of the lander created no trouble. The only casualty of the lunar liftoff was Tom Moser’s flag. Planted too close to the lander, it fell over in the engine’s exhaust.
The legless version of the lander rejoined the rest of the Apollo spacecraft, and all three astronauts gathered together in the command module, preparing for a two-day trip back to Earth. One of the only remarkable moments of their return ca
me within the closed eyes of the astronauts. Space was truly not black. Stars of the Milky Way spilled across the heavens, and shafts of sunlight made hour-long orbits within the capsule as it spun in barbecue mode. Even then, instrument lights and indicators had their own patterns and rhythms around the astronauts. Shut-eye did not come easily, but orders were orders, and the crew attempted to sleep. Even with their eyes closed, space toyed with them. Astronauts later reported seeing bright flashes, at random intervals. Were they hallucinating or maybe just exhausted, with fried nerves?
Weeks later, when a particle physicist heard of this odd event, he ran to his local particle accelerator at Lawrence Berkeley Laboratories. He had predicted these flashes might occur but had never tested the idea. Worried only with discovery, he donned an opaque hood, closed his eyes, and lowered his usually brilliant head into the accelerator’s beam line and the rush of heavy ions. Sure enough: flashes! Super-energetic (and most probably harmful) particles interacted with the eye’s inner liquid, creating a cascade of light. The astronauts, even absent a solar flare, were unwitting targets of heavy cosmic rays. These relatively hefty, invisible bullets stream through space in all directions.
We still aren’t completely sure where these heavy cosmic rays started. We believe they likely erupted from exploding stars and have been traveling about our galaxy for millions of years. The full health impact on our bodies is also murky; we know it can’t be good, but the question is simply “How bad?” How much of a radiation dosage did the Apollo astronauts receive? According to Dr. Eugene Benton, a physicist who helped develop Apollo’s radiation detectors, each astronaut wore three—chest, thigh, and ankle—and for a full Moon mission, these detectors each recorded a handful of heavy cosmic ray impacts. But since these rays can include, for instance, the guts of an iron atom moving at a good fraction the speed of light, they can do some damage. And if the little detectors each registered a few impacts, an astronaut’s entire body endured hundreds or even thousands. One recent study shows that the astronauts who’ve left Earth’s influence for several days have had surprisingly high rates of cardiovascular damage compared to earthbound humans.iv While we can debate the effect of a week-long trip to the Moon, the issue of heavy cosmic rays looms large for missions to Mars or beyond.32
The Apollo Chronicles Page 27