Engineer Moser says it was still useful on ice with two dimensions of motion (everything but up and down), and one type of rotation (the left-right turning of “yaw”). But their test “space ships” didn’t look the part. They were more like the offspring of wooden shipping pallets and primitive go-cart frames, each with an early piece of docking hardware tacked to one end.9
My parents made a move to Los Angeles in 1962, where my father started work on a vexing Moon problem: computing an exact travel path. Physics is very good at trajectories in general, and the discipline had two solid centuries of practice with artillery, but this Moon problem was something new. NASA needed to launch a craft from a spinning orb and have it hit another, smaller spinning orb at a distance of 240,000 miles—not hit, exactly, but rather slide carefully into a perfect orbit around that smaller body. Some engineers compared the task to aiming a rifle at a moving basketball many miles away, but to achieve orbit, the bullet would have to skirt the edge of the basketball by a fraction of an inch.10 The engineers also had to reckon with an ever-changing tug on the spaceship. Earth’s pull would decrease, mile by mile, once the ship embarked, and at some point a new pull would commence toward the Moon.
My father’s new job involved working for Howard Hughes’s aircraft company, as they contracted with NASA’s Jet Propulsion Laboratory in southern California. This branch of NASA led, and still leads, the charge in unmanned probes. The overall plan called for robotic probes to orbit, photograph, and prod the Moon. Apollo could then find a safe spot to land with astronauts.
Shooting probes to the Moon had proven to be risky by 1962. Most of the Soviet Luna probes had missed their marks widely, if they even escaped Earth’s gravity, and some had even crashed into the Moon unintentionally. America hadn’t fared much better. The Ranger 3 probe had suffered a guidance system failure, and like a bad field goal attempt, it had sailed wide of its mark. And months later, Ranger 4’s primitive computer had seized up on the way to the Moon, and with engineers wincing, the probe slammed into its target as braindead as a rock, learning nothing.
My father worked on the new Surveyor program, aiming to set probes onto the lunar surface. Hughes Aircraft, as the prime contractor, had a small team working on trajectories to the Moon. “I can’t believe I used to do things like this,” he says, looking at one of his papers from that era. The paper, with Robert Brown as the first of several authors, is called “The Generation of Lunar Trajectory Differential Coefficients using Patched Conic Technique,” and its ten dense pages weave together mathematical equations and numeric tables. A “patched conic” is just a fancy way of suggesting that, mathematically, as a ship moves from Earth to the Moon, at some point we quit referencing its position using Earth as the mathematical origin. At some point, the ship is truly now in the Moon’s system, its realm of gravitational dominance. But there is no simple way to change your equations from those using Earth as a zero point to another set using the Moon as a zero point. The entire ten pages of equations addressed this mathematical hand-off for the fledgling Surveyor program.
As retired engineer and trajectory mastermind Hal Beck explains, there was no clean and exact solution for finding a path to the Moon. Engineers didn’t arrive at one equation, with one pleasing mathematical curve, for each trip to the Moon. Instead, they took a stepping-stone approach, where each stone was one little chunk of time on the way to the Moon. “It’s hard to imagine, but . . . a lot of the work was done with a 32K [32 kilobytes] machine memory, and a lot of it was done with 64K, and that’s almost no memory compared with even a small hand calculator [today],” Beck said. “When you would do long computations, you would take a time step and go through the computation and compute all the parameters [location, speed, heading, etc.] . . . and just print them.” Then they would move their hypothetical spacecraft one more time-step forward, on its mathematical way to the Moon, and start all those computations again. “As a result, when you computed a lunar trajectory, you’d have a stack of paper like a foot thick.”11
These early electronic computations formed a challenging bottleneck. “Machine time was so precious and lunar trajectory iterations were so consuming,” Beck said. With the new Space Center still under construction, NASA engineers worked in their disparate locations and had to borrow computer time at the University of Houston. One competitor for such a precious resource was Langley transplant Marlowe Cassetti. While people like Beck needed the computers to help them find paths to the Moon, Cassetti was trying to compute exactly when to coax a Mercury capsule out of Earth orbit so that it would hit the Pacific Ocean at just the right time and just the right place. He recalls getting a taxi ride to the University of Houston’s computing center during one of the frequent thunderstorms. Rainwater came spouting out from the sewers so fast “they were lifting the iron manhole covers off.” Cassetti would gather his set of computer cards—the stack of carefully punched cards contained the program he needed to run, with the thumb drive still many decades away—and run through the rain. “You’d carry them in there, you’d submit them to a dispatcher, and then basically you don’t get any results ’til the next day.”
And he was often disappointed. “There was a high failure rate in those days,” he said. “You’d punch one number wrong into a card, and you got a bunch of wasted paper, a big printout of garbage . . . one card out of order or one keypunch mistake . . . you wouldn’t get any kind of diagnostic. . . . It would give you what was called a ‘core dump,’ just a bunch of octal numbers that didn’t mean anything.” Even when he’d punched all his numbers in correctly, he might be thwarted. “People don’t realize, but in the early sixties, computers were tremendously unreliable. Very poor in terms of mean time between failures.” In NASA’s early years, failure was not only an option but also a common side dish to any project.
Beck, working on Apollo’s exact lunar glide, was similarly frustrated, eventually calling this work—the stepwise, grinding computation for a trajectory to the Moon—the greatest challenge of his career. “It was so terribly sensitive,” he said. “To tune that software and get it to function was a very frustrating job and took a lot of midnight hours,” he said. And doubts left a pit in his stomach. “We were always faced with the possibility that it might not work.” Even years later, when the first Apollo craft appeared to find its mark and slip into a perfect orbit around the Moon, he had to hold his breath waiting for the craft to appear again from the far side. Had their calculations worked? “It could come out at the wrong time, or it could be shooting off into space somewhere,” he said.
Cassetti recalled a sort of unfortunate competition, given limited computer resources. The person running the university’s computer center was a political appointee, according to Marlowe, and the fellow held little interest in the details of their work and deadlines. Under his watch, the computer center didn’t seem to use much logic in determining which jobs got done first. “Occasionally I would tell our guys, we got to have this thing run by tomorrow,” Cassetti said. “Wrap the cards in a five-dollar bill if that helps. It was so nonsensical.”
But Beck had a secret computer technique, and his requests sometimes eased ahead of those from Cassetti and other anxious engineers: the trunk of his white Austin Healey convertible. “It was a sweet car, man,” he says now. When dropping off his computer jobs with the night-shift university staff, “I’d give those guys a key to my trunk. I’d come back at six o’clock [in the morning] and have a big stack of results.” The trunk hid an ice chest full of beer and a tacit understanding: the cans could disappear as long as the staff ran Beck’s jobs (see Figure 6.2).12
figure 6.2 Could you say “no” to this man’s computer requests? Hal Beck shows off his Austin Healy in 1962. (Photograph courtesy Hal Beck.)
The following year, NASA started buying more of its own computers. Engineer Ken Young recalled an IBM 1620 housed at the Houston Petroleum Center. At first, he felt lucky to have an office with just two people, instead of the normal three or four o
ffice mates. But their office sat next to the room reserved for the 1620, and even on the hottest summer days Houston could muster, the two engineers were uncomfortably cold. Mainframe computers need cool temperatures to keep themselves from overheating. The engineer and his office mate would sometimes try to sneak the thermostat up a few degrees, but they found a note from the head secretary charged with guarding this taxpayer investment: “The next person who touches this thermostat will be fired immediately.”
Aside from borrowing and buying large early computers, NASA made a smart gamble on a new technology called an “integrated circuit,” or a computer chip. The first such devices trickled onto the market in 1961 from Fairchild Semiconductor, and by 1963, NASA consumed about 60 percent of the company’s chip output. The agency made a bold decision for the early 1960s: having Moon missions take their own computers along for the ride. These machines would need to be compact, lightweight, and reliable to an extent no computer had ever been. They would be violently jostled, zapped by space radiation, exposed to all sorts of possible temperatures, and operated by tired, stressed astronauts who were in no way computer experts. NASA tasked MIT’s Instrumentation Laboratory with designing the Apollo onboard computers. And the Instrument Lab asked their young engineers if they could try to make such a thing work with these newfangled integrated circuits.13
Just as engineers in Massachusetts worked on a newly petite scale of circuit architecture, another set of engineers, in Alabama, worked on rockets more massive than any before. The architecture of the eventual Moon rocket began to come together, at least on paper. A set of five new keroseneii and oxygen engines, the largest ever of their kind, would power the first (bottom-most) stage of the Saturn V. And once that stage was exhausted of fuel and discarded, about forty miles in the air, the second and third stages would use something more novel: hydrogen-burning engines. In sum, the initial launch would be a brute-force affair, basically amplifying signatures of the German V-2 rocket, and then the next stages, moving into Earth orbit and beyond, would employ something futuristic, at least to the mind of young Marlowe Cassetti. “I said gosh, I can’t believe they are building a hydrogen fueled rocket, almost like a science fiction type of thing.”14 But in 1962, both engine types were causing significant trouble.
For the first stage, each new kerosene-burning engine (labeled an “F-1”) would combine two tons of liquid oxygen and one ton of kerosene, per second, letting them burn at about 5,000˚ Fahrenheit, the temperature of a mild red star. To keep the combustion chamber from melting, the engineers used a clever trick from von Braun’s V-2 rocket. Plumbing guided liquid oxygen, at –300˚ Fahrenheit, to fill a network of tiny tubes throughout the walls of the combustion chamber’s bell, both cooling the chamber and also pre-warming the oxygen, before bringing it back up to meet its kerosene partner for their collaborative burn. But some voices warned that the ambitious F-1 engine might simply be too big, too thirsty, and too hot to ever work reliably. Fears grew in the summer of 1962. Rocketdyne, the company building the engines for Huntsville, ran a test in the remote Mojave Desert. They lit a prototype engine but watched it explode within a fraction of a second.
The most vexing problem for these mega-engines was called “combustion instability.” Like a guttering candle flame, a rocket engine can develop an unwelcome pattern of fluttering burn rate, from bright and fast to dim and slow and back again, over and over. Once these pulses start thrumming in an engine, they usually don’t stop, and the bell surrounding the combustion chamber can start vibrating like a chiming wine glass until it breaks. Even if the problem doesn’t destroy the engine entirely, it can create what the rocket scientists named a “pogo” effect in honor of the bouncing children’s stick. Like a car repeatedly lurching and braking, the engine instability creates a herky-jerky ride for the rocket, its equipment, and the eventual astronauts, endangering them all.
To further complicate the engineering detective work, two types of instability emerged: a lower-pitched variety that could arise within the structure of the rocket, and a higher-pitched version that came from the engine bell itself. Faget’s boyhood friend and longtime collaborator Guy Thibodaux compared it to a musical instrument. “On an oboe, you finger,” he said, to change the tone coming out of it. But “you don’t change the frequency in rockets,” at least not without significant cost and redesign.
Later that year, von Braun shared his worries in an internal NASA memo. He said the problem was assuming “new proportions” and that no single theory or idea could eliminate the instabilities. Engineers were left, he said, with an “empirical” approach—a trial-and-error game of shave this part, make that one thicker, poke an extra hole over here—which was expensive, dangerous, and, most of all, consuming time they did not have.15
Meanwhile, the second stage, built to take the Saturn rocket and its Apollo adornment through the upper atmosphere, was also providing major headaches. It’s worth a bit of a deeper dive here, just to show the “hip bone connected to the leg bone” type of problems that plagued the Apollo program. Like the first, the second stage had five engines, but these relied on a technology that Marlowe Cassetti had viewed as Flash Gordon or Buck Rogers come to life. These engines would combine oxygen with hydrogen. As a very lightweight fuel, hydrogen gives rocketry the greatest bang for the buck. (Engineers talk of “specific impulse” for a fuel or an engine, which essentially measures how much kick it gives per gallon of fuel guzzled.) To be sure, using hydrogen created new headaches. To store it compactly within a rocket, engineers had to liquefy it, requiring a chilly –423˚ Fahrenheit. But the combination of its light weight and its incredible burning power was too great to ignore.
Hydrogen actually burns with a light we cannot see. Astronomy fans may pause and point out that the sun itself burns hydrogen, and is happily visible to us. But it’s a completely different “burn”—the sun is using a nuclear reaction instead of a chemical one—and in any case, the sun is more like a hot poker than a flame. It sends out light based on its incredible temperature. The fact that we can’t see hydrogen burning led to some unique quandaries for NASA and its contractors. In building and testing the new engines, engineers would occasionally encounter a leaking hydrogen line, and since hydrogen is so flammable, it could even start burning. You might hear it, but you would never see the flame. Bob Austin (he who recorded Sputnik’s beeps and nearly destroyed his grandmother’s kitchen making homemade rocket fuel) relays stories of a “broom test.” If the engineers knew they had a hydrogen leak burning but didn’t know where, they would move slowly along the hydrogen line or hydrogen tank, waving a broom in front of them. When the broom suddenly caught fire, they’d found their leak.
Having two super-cold fluids in stage II also created a novel design problem, especially since these fluids made up more than 90 percent of the stage’s weight, when filled for launch. Super-cold liquids, if sitting in Earth’s relatively warm atmosphere, boil and turn to gas, so we store such liquids in a fancy sort of thermos to slow the boil-off rate. They will keep turning to gas, but you can slow the bubbling to a crawl using good insulation. Stage II had 83,000 gallons of liquid oxygen, at –297˚ Fahrenheit, and 260,000 gallons of liquid hydrogen, at –423˚ Fahrenheit, and ideally they would each have their own separate insulated tank. But insulated tanks are heavy, and every extra pound on the second stage meant more lifting work for the first stage. The problems hit one another like dominos: if the second stage gained weight, and the first stage needed to do more work to lift its sibling, the final result meant the actual Apollo spaceship suffered mandatory weight loss. Its every system, including life support, would be thinner. The craft would simply hold fewer back-up options when things went wrong.
NASA decided (with their contractors at North American) to have the two super-cold tanks actually share a metallic wall between them. That decision saved a lot of weight, but the wall had to protect the colder hydrogen from the relatively warmer oxygen, or else the hydrogen would start boiling away befor
e it could be burned. Engineers found a metal that could work, a special alloy of aluminum. Here, one of 1962’s central problems unfurled like a roll of metal before the engineers. First, the size of these tanks was unprecedented for storing super-cold liquids. Next, the seams of the tanks needed the most precise and reliable welding jobs that America had ever achieved. And finally, the one metal that would work, the special type of aluminum, was notoriously difficult to weld. It would be one thing to do a tricky welding job for a few inches, or even a few feet, but stage II was nearly eighty feet high and two hundred feet around. The Huntsville team, and their contractors, had to invent new methods of welding and make sure these seams could then withstand a violent ride to space.16
Separate from welding the tanks, a glimmer of progress came from the avant-garde hydrogen engines themselves. Early tests had shown hydrogen burning with such fury as to melt most components around it, including copper pieces in the engine. But in 1962, engineers ran a prototype hydrogen engine for about four successful minutes without any part melting or exploding or fracturing. That might not seem very long, but the plan for stage II only needed it to fire for six minutes, roughly tripling the mission’s altitude along the way.17
Meanwhile, a chance meeting in Huntsville solved an earthbound problem in 1962. A representative from a large equipment manufacturing company visited von Braun’s outfit to discuss a crane they might need to stack rocket stages. But the rep overheard talk of a problem at the Cape: How would they move colossal Saturn rockets from an enclosed staging area to the launch pad, miles away? He thought his company had just the thing: vehicles the size of parking lots that stripped Kentucky soil away from seams of coal. These crawlers had tank treads, and, as he told the Huntsville engineers, the machines could self-level, meaning one could keep its roof completely horizontal, even though its treads were climbing a hill. What could be better for moving one of the world’s tallest, heaviest objects?
The Apollo Chronicles Page 11