Apollo: The Race To The Moon

by Catherine Bly Cox

A fourth gimbal would have taken care of the problem—no matter what crazy position the spacecraft got itself into, the platform would have remained steady as long as the guidance system remained powered up. Gemini had used a four-gimbal system. But a fourth gimbal would have been heavy. It would have added substantially to the bulk of the system, because it would have had to fit around the other three. And the Instrumentation Lab at M.I.T., which designed the system, was comfortable with three gimbals—that’s what the Lab had used for Polaris. Three gimbals were enough for any maneuver the spacecraft might be required to make, as long as everyone paid attention to what was happening. After a long battle with the astronauts (Jim McDivitt threatened not to fly in a spacecraft without a fourth gimbal), a three-gimbal system was used.

In the event that the spacecraft did accidentally go into gimbal lock, it would be possible to realign a platform from scratch, but, as on Apollo 12, it was a complicated, tedious job. And most certainly, Fenner wanted to avoid gimbal lock with a spacecraft that already seemed to have more problems than it could handle. Now, he was warning Kranz that the spacecraft was moving unpredictably. Pushed by an unidentified force, Odyssey was vulnerable to gimbal lock.

14 minutes. Lovell reported seeing something venting from the service module—a gas of some sort. He didn’t say so, but in his own mind he was pretty sure it was oxygen—the O2 Tank 2 pressure was reading zero and there was a big sheet of what looked like white smoke out his window. It added up. He was also pretty sure that it was only a matter of time until the C.S.M. went dead. For Lovell, the moment when he looked out the window and saw the venting was the mom...

Kranz understood the implications too, and knew that everyone else in the room had heard Lovell’s calm report. He decided it was time to give a little speech to the controllers. “Okay, now, let’s everybody keep cool,” he began. “We got the LEM still attached, the LEM spacecraft’s good, so if we need to get back home we got a LEM to do a good portion of it with.” He went through the priorities: Don’t blow the command module’s internal batteries, don’t do anything to blow the remaining Main Bus. “Let’s solve the problem,” he concluded, “but let’s not make it any worse by guessing.” Kranz spat out the word as if it were an epithet.

The SimSups’ favorite trick was to confuse the controllers with instrumentation problems and then “while you were off chasing the flaky readouts they would drop the hammer on you with some real big failure and see how well you could back out of that.” The simulations always had a way out; surely this situation must have a way out as well. To Aaron, it was as if the controllers were saying, “We’re not going to give up, we’re not going to give up, we can’t give up, we’ve never had this happen before.” He began preaching to them in his Oklahoma twang. “You guys are wasting your time,” he said to them. “You’re convincing yourself this is some kind of funny instrumentation problem. You really need to understand that the C.S.M. is dying.”

Kranz, like Kraft, had formulated some precepts of flight control, and one of his favorites was “Tread lightly, lest ye step in shit.” He had been trying, he recalled, to “move very easily and progressively through this thing—because you did not want to close out any of your options for any of the systems, because you never knew which ones you were going to get.” At this point, the options were dwindling to a precarious handful.

“The pressure in O2 Tank 1 is all the way down to 297. You’d better think about getting in the LEM and using the LEM systems. I’m going to have to power way down. I don’t know if I’m going to be able to save the O2 for the [remaining] fuel cell.” Liebergot, like Aaron, now knew that the command module was dying. If that was true, the only way the crew could get back was by getting into the LEM and surviving on its oxygen, water, and power.

“There’s a possibility that there could be a leak between that reactant valve and the rate sensor,” Brown conceded. “If there is, then shutting it off may help us. But that’d be a dual failure, not a single failure.” And a dual failure still seemed as improbable to both of them as it ever had. EECOM pondered that for a moment. Finally Liebergot said, “It’d have to be in the cryo tanks for them both [both fuel cells] to go.” “Somewhere back there,” Brown agreed. But, still, that left the problem of explaining why both O2 tanks were failing. Then the nickel dropped. “Yeah, that’s right, it’s common,” Liebergot said excitedly. “Dick, if you blasted a hole downstream between the rate transducer and the reactant valve, that’d be, that, that—Liebergot could barely get the words out, it suddenly seemed so obvious—“that’s manifold right there, all three cells.” He was very close to the truth.

And it was then that Sy Liebergot began to understand the basics, though it would be many more weeks before anyone would fully understand the night’s events. In fact, unearthing the truth took an investigative board similar to the one established after the 204 fire. Scott Simpkinson oversaw M.S.C.'s part of the investigation. Don Arabian headed the team of engineers who, in a tour de force of engineering detective work, tracked down the convoluted history of O2 Tank 2. As the finishing touch, Arabian took an identical O2 tank, subjected it to exactly the sequence of events that he believed to have caused the Apollo 13 anomaly, and produced exactly the same result. This is what had happened:

In October 1968, when the O2 Tank 2 used in Apollo 13 was at North American, it was dropped. It was only a two-inch drop, and no one could detect any damage, but it seems likely that the jolt loosened the fill tube that put liquid oxygen into the tank. In March 1970, three weeks before the flight, Apollo 13 underwent its Countdown Demonstration Test that, like all C.D.D.T.s, involved loading all the cryos. When the test was over, O2 Tank 2 was still 92 percent full, and it wouldn’t detank normally—probably because of the loose fill tube. Because a problem in the fill tube would have no effect on the tank’s operation during flight, the malfunction was not thought to be relevant to flight safety. After three unsuccessful attempts to empty the tank, it was decided to boil off the oxygen by using the internal heater and fan. This was considered to be the best procedure because it reproduced the way the system would work during flight: heating the liquid oxygen, raising its pressure, converting it to gas, and expelling it through the valves and pipes into the fuel cells where, in flight, it would react with the hydrogen. So they turned on the tank’s heater. A technician working the night shift on Pad 39A was assigned to keep an eye on the tank temperature gauge and make sure that it did not go over 85 degrees Fahrenheit. It was not really necessary that a human serve this function, because a safety switch inside the tank would cut off the heaters if the temperature went beyond ...

On all the Apollo flights up through Twelve, the switches had not had to open. When the tanks were pressurized with cryogens hundreds of degrees below zero, the switches remained cool and closed. When, for the first time in the history of the cryo tanks, the temperature in the tanks rose high enough to trigger the switch—as O2 Tank 2 emptied—the switch was instantaneously fused shut by the 65-volt surge of power that it had not been designed to handle. For the eight hours that the heaters remained on, the Teflon insulation on the wires inside the cryo tank baked and cracked open, exposing bare wires. On the evening of April 13, when Liebergot ordered the cryo stir, some minute shift in the position of two of those bare wires resulted in an electrical short circuit, which in turn ignited the Teflon, heating the liquid oxygen. About sixteen seconds later, the pressure in O2 Tank 2 began to rise. The Teflon materials burned up toward the dome of the tank, where a larger amount of Teflon was concentrated, and the fire within the tank, fed by the liquid oxygen it was heating, grew fierce. In the final four seconds of this sequence, the pressure exceeded the limits of the tank and ble...

The resulting gases blew out one of the panels in the service module. That explosion also probably broke a small line that fed a pressure sensor on the outside of O2 Tank 1, opening a small leak. Once the service module panel blew out, the vacuum of space extinguished the fire. All the crew knew was that something had made a loud bang and jolted the spacecraft. Actually, the crew of Thirteen was exceedingly lucky. The explosive force could have broken the tension ties holding the command module to the service module, depriving Odyssey of the precious few hours the remaining fuel cell gave them. It could have cracked the heat shield. Or the wiring in the tank could have short-circuited later in the mission, after the LEM had already been used for the lunar landing. If the explosion h...

At 55 hours, 54 minutes, and 44 seconds into the mission, the pressure stood at 996 p.s.i.—high, but still within the accepted limits. One second later, it peaked at 1,008 p.s.i. By 55:54:48, it had fallen to 19 p.s.i. During those same four seconds, the temperature in the tank went from –329 to +84 degrees Fahrenheit. If one of them had seen the pressure continue on through the outer limits, then plunge, he would have been able to deduce that O2 Tank 2 had exploded. It would have been a comparatively small leap to hypothesize that the explosion had damaged the piping from the second O2 tank as well. And once they had been able to conceive of something having occurred that disabled both oxygen tanks, then the problems reported in the electrical system would have made sense.

Now Lunney had exhausted the alternatives, and he turned his full attention to getting Aquarius ready to serve as a lifeboat. By this time the notion of using the LEM to power the C.S.M. had been discarded. The plan was to have the crew live in Aquarius until just before entry, when they would move back into the C.S.M. and power up with the C.S.M.’s three internal batteries that were its source of power for the last phase of the flight.

Tom Stafford, who had commanded Apollo 10 a year earlier, was in the MOCR listening to this exchange. As soon as it was over he approached Lunney for a private conversation. They were on the wrong track, Stafford said. Maneuvering the docked spacecraft with the LEM’s thrusters to get manual star sightings was going to be next to impossible. It was essential they get an alignment now, from the C.S.M., while it still had power. Stafford’s was the knowledge of a man who had flown the LEM, and Lunney respected it.

Like a variety-show juggler with a dozen plates spinning on the top of sticks, Lunney went from one decision to another, keeping the plates spinning, sometimes getting back to the one at the other end of the row only when it seemed to be wobbling on its last revolution. Throughout it all, Lunney, aged thirty-three, maintained the mildly distracted air of an experienced parent getting many small children ready for school.

Lunney grunted softly, as if someone had just hit him in the stomach—which is how he described that moment years later. It was like a blow, and then like a hole into which his stomach and the rest of him were starting to slide. It was the one time during the entire night, he recalled, when for a moment he backed away from the rush of events and “had a sense of ‘Holy Christ, it’s this bad. It has really happened this way.’” The surge tank was the last reserve of oxygen. It had to be protected for the entry, and now Burton wanted him to use part of it, lest the crew asphyxiate.

Aquarius carried 338 pounds of water in its tanks. During the first hours after the crew moved in, the LEM was consuming water at the rate of 6.3 pounds per hour. Arithmetic immediately revealed that, at that rate of consumption, Aquarius would have no water at all after fifty-four more hours—twenty-three fewer hours than the fastest possible return to earth. The astronauts would survive without water for the extra twenty-three hours, but the equipment wouldn’t.

As the men in the MER and at Bethpage calculated the maneuvers Aquarius would have to make and the power it would take from the LEM to power up the partially depleted entry batteries in Odyssey, it was decided that Aquarius would somehow have to use a maximum of 15 amps when it was not maneuvering. Until the day of the accident, the LEM’s designers had calculated that the LEM’s minimal configuration used 20 amps.

Each was sensitive to the critical nature of his own piece of the puzzle (for example, it could be disastrous if the A.S.A. failed to detect a malfunction in the DPS during the next burn). The temptation to insist that his piece of equipment be operated within the tolerances for which it had been designed was powerful. And yet each also understood that somehow the voltages and the heat sources in the lunar module had to be cut drastically. Small dramas were played out all over the country as designers passed on the word, usually with too little data to be sure they were right, that their babies would continue to function under the unprecedented conditions that Houston was proposing.

Years later, John Strakosch, a Grumman engineer at Bethpage, would say it was the most intensely concentrated work he’d ever done—an effort that in his memory seemed to last eighteen or twenty hours. His handwritten log of his activities reveals that it lasted for what amounted to three unbroken days.

In the process of inventorying the consumables during the first night, someone discovered that, as things stood, the astronauts would asphyxiate from carbon dioxide buildup before they got home. In both the LEM and the command module, carbon dioxide was removed by circulating the air through canisters of lithium hydroxide. The problem was that Aquarius had only two such canisters, not nearly enough to last the journey home. Odyssey had plenty of canisters, but they were the wrong size and shape to fit the LEM’s equipment.

Kraft explained their three options. They could, if they chose, bring the crew back in less than thirty-six hours after P.C.+2 with a long burn at full throttle if they were willing to bring Odyssey down in the Atlantic where NASA had no recovery ships. Kraft didn’t spend much time on this option, for it was only a few hours faster than the second one, thereafter called the “fast burn,” which would put the spacecraft in the southwest Pacific, the prime recovery area, in less than thirty-nine hours. The third option was a shorter, lower-power burn (the “slow burn”) that would return the spacecraft to the prime recovery area in sixty-three hours, or twenty-four hours later than the fast burn. They had no intermediate choices if they wanted to land in the prime recovery area. A spacecraft returning from the moon had limited maneuvering range. If one wanted to put the space in a particular spot along the potential landing track, it was available only once per earth rotation.

The fast burn would take virtually all the propellants that the LEM had, they explained, with little energy left for tweaking the trajectory if it were in error. It didn’t take much of an error in the burn to make tweaking necessary—at 240,000 miles away, an error of a tenth of a foot per second in a burn could compound in such a way that the spacecraft would miss the earth altogether.

Each of the major participants in Apollo 13 remembered a different moment that, to him, represented ultimate crisis. For Lunney it was the final few minutes of the transfer from Odyssey to Aquarius. For Gerry Griffin and Jim Lovell, the “biggest heart-stopper” (in Lovell’s words) occurred while they were preparing for the P.C.+2 burn.

The technical problems of piloting that Lovell and Haise faced—Swigert, as command module pilot, wasn’t trained to fly the LEM—were enormous. Aquarius was about the same length as the C.S.M., but it was little more than half the weight, and the LEM’s biggest engine, the DPS, had less than half the thrust of the C.S.M.’s engine. Using Aquarius to guide the C.S.M. was like using a small car to push a limousine, but in three dimensions, with requirements for precise adjustment. It had already been a problem during the first night, when Lovell and Haise had had to maneuver the assembly into a passive thermal control (P.T.C.) mode, the slow, turning-on-a-spit spin that Joe Shea had suggested five years earlier. It became an even bigger problem on Monday afternoon, when Aquarius had to get a star sighting to prepare for the P.C.+2 burn.

Before each major maneuver, the astronauts went through a straightforward and largely automated procedure. The astronauts would select an appropriate star from their list and ask the spacecraft to find it for them. The spacecraft, consulting the I.M.U., would orient itself so that, if the platform was properly aligned, the star in question would be centered in the cross hairs of the crew’s sextant, the A.O.T. (Alignment Optical Telescope). If the star wasn’t exactly centered, the astronaut looking through the A.O.T. made the necessary adjustment to center it, and the computer entered the adjustment into the I.M.U., which then corrected itself. When the crew of Thirteen tried to do this with the alignment it had borrowed from the C.S.M., they found that the debris from the explosion in the service module still accompanied them, reflecting light and creating a swarm of false stars indistinguishable from the real ones. They reported the problem to the ground. “A genius in Mission Control,” Lovell wrote in his account of Apollo 13, suggested using the sun instead (it was Ken Russell, the lead Guido). Not even the particles from the debris could block out a target as large as the sun.

completely novel checklist, one that took into account a host of anomalous factors. The batteries in the C.S.M. would have to function for a matter of hours instead of the usual half-hour or forty-five minutes. The LEM was going to execute preparatory maneuvers that were ordinarily done with the S.P.S. engine. The crew would be powering up a command module that had been cold and wet for more than three days. Once the White Team had compiled this checklist, they would have to couch it in such a way that its hundreds of steps could be copied and understood by an exhausted crew.

On that same Wednesday morning, the lithium hydroxide in Aquarius was depleted and the carbon dioxide levels approached the danger point. By that time, however, a solution had been passed up to the crew. Working nonstop since the early hours of the explosion, members of the Crew Systems Division had invented a box that could hold the C.S.M.’s lithium hydroxide canisters and be connected to a hose in the LEM ordinarily used to suck air out of space suits. The box was built out of storage bags, tape, and the stiff plastic covers from the crew’s checklist book. The remaining problem, once the people in Crew Systems had figured out a solution, was explaining to the crew what they had done. Hours had been spent carefully working out verbal instructions for building a contraption that the crew had never seen. (Which would be more accurately understood: Cut a piece of tape “thirty inches long” or “a good arm’s length”?) CapCom read up the instructions, Haise assembled the materials, and Swigert and Lovell managed to put it together before the carbon dioxide level became intolerable. Within a few hours, the level was back to normal.

After many iterations, the tiger team had completed a checklist that they thought would work. It also left a 16 amp-hours margin, the minimum that the recovery people insisted upon in case the Odyssey landed in the Stable 2, or upside-down, position in the ocean. This stringent budget was taken over to the flight simulators, where Ken Mattingly, the astronaut who would have been on Apollo 13 if he had not been exposed to the measles, tried it out. To Mattingly’s surprise, the hastily prepared checklist worked without a hitch. But instead of landing with a 16-amp-hour surplus, Mattingly ended with a 10-amp-hour deficit. There was no place to cut. Aaron was already holding most of the systems to budgets that the controllers had originally said they couldn’t possibly live with. Bill Peters, the lead TELMU, came to the rescue. He was now confident that Aquarius would have a small reserve of battery power. The spacecraft’s design provided for power to flow from the C.S.M. to the LEM, to top off the LEM’s batteries. The MER had figured out a way to do it backwards. Aaron could gain 20 amp-hours by using Aquarius to charge Odyssey’s half-depleted Battery A.

An Apollo spacecraft returning to earth from the moon did not aim directly at the earth, a passage that no heat shield could survive. Rather, it aimed at the leading edge of the earth so that, as the spacecraft sped by, it would be caught by the earth’s atmosphere and gravity. If the spacecraft was too far from the leading edge, it would continue past the earth into an elongated earth orbit. If it was too close to the leading edge, it would enter the atmosphere at a steep angle and burn up. The area that was neither too high nor too low was about a degree and a half wide—ten miles wide at the point of entry—and was called the entry corridor. From Apollo 8 onward, one of the chief functions of the Trench was to make certain that the returning spacecraft was in the middle of it.

Separation of the service module came at 138 hours into the mission, four and a half hours before splashdown. From his station in Odyssey, Swigert couldn’t see the service module as it drifted away. He could, however, hear excited voices from Aquarius. “There’s one whole side of the spacecraft missing,” Lovell reported to the ground. Wires were dangling, the area around the oxygen tanks was a tangle of ripped metal—“It’s really a mess,” Haise said. Until then, no one had realized the magnitude of the explosion.

Chuck Deiterich listened over the loops and felt a chill. The oxygen tanks were close to the base of the heat shield. The obvious possibility was that the heat shield had been damaged, perhaps even cracked. “I think everybody in the room had the same idea at the same time,” Deiterich recalled. “Everybody knew where the oxygen tank was. Nobody said a word about it. There was nothing anybody could do.”

The last exchange between the crew and the ground began on an unsettling note. “I know all of us here want to thank all you guys down there for the very fine job you did,” Swigert said, as if he thought this might be his last chance to say it. Then the atmosphere lightened. “I sure wish I could go to the FIDO party tonight,” added Swigert, a bachelor with a Center-wide reputation as a ladies’ man. CapCom Joe Kerwin advised Swigert that the controllers would be glad to call any phone numbers that Swigert might want to pass down.

Apollo 13 was also the last moment when the nation was transfixed by the adventure. When the initial commitment was made in 1961, it seemed that landing a man on the moon would be just a beginning, a foray by scouts to be followed by outposts and then by settlers. It was this kind of thinking in the early 1960s that enabled Stanley Kubrick to begin a movie about a voyage to Jupiter via a huge space station and lunar colony and plausibly entitle it 2001.

By the time the movie was released in 1968, the title was already implausible, for the space program’s grip on the public imagination had begun to fade even before the first moon landing. Whether this was inevitable or an unlucky juxtaposition of Apollo with Vietnam and domestic upheaval will never be known. But what had been imagined as a natural process of growth in manned space travel had by 1970 come to be seen as a technological exercise that wasn’t worth the effort.

Unimpressed by the claims of spin-offs, NASA’s critics conceded only that Apollo had shown what the nation could accomplish if it really tried. A new all-purpose political platitude entered the language: “If this nation can put a man on the moon, then it should be able to . . .” Cure cancer. Stop crime. End poverty. All it would take, many seemed to think at the time, was the same kind of money and commitment that the United States had lavished on Apollo.

NASA itself had already begun to change by the time Thirteen flew, a point that many of its veterans have made. The truly fun parts of the manned space program, so many said, were Mercury and Gemini and the planning years of Apollo, when the centers were still independent and feisty, collaborating when it suited them, sometimes going their own inefficiently separate ways—but also electric with enthusiasm and imagination, prodigiously inventive. Then, for the last half of the 1960s, NASA seemed to be getting the best of both worlds—superb management without bureaucratic paralysis. By 1970, it was apparent that the bureaucracy was going to become more and more dominant, and it was acting more and more like bureaucracies elsewhere. Maybe organizations, like people, can’t stay young forever, the veterans conceded. But it sure was fun while it lasted.

Armstrong and Aldrin had spent two hours and forty minutes on a single E.V.A., never moving more than a few hundred feet from the LEM. Apollo 15’s lunar astronauts, Dave Scott and Jim Irwin, spent nineteen hours outside the LEM and traversed seventeen miles exploring the terrain around a 15,000-foot mountain. On Apollo 16, John Young and Charlie Duke descended to the lunar highlands and remained on the surface for three days. On Apollo 17, Gene Cernan and Harrison (Jack) Schmitt spent even longer in the Taurus Littrow area, traversing almost twenty-two miles during more than twenty-two hours of E.V.A.s.

The last Apollo flight lifted off from Pad 39A at half past midnight on December 7, 1972. It was the only Saturn V ever launched at night.

Apollo 17 was commanded by Gene Cernan, veteran of Gemini IX and Apollo 10, the only man besides Jim Lovell and John Young to go twice on a lunar journey. His CMP was Ron Evans and his LMP was Jack Schmitt, a geologist with a Ph.D and the only scientist to be on an Apollo crew. The command module was named America; the lunar module, Challenger. On the early afternoon of December 11, Cernan and Schmitt landed Challenger in the valley of Taurus Littrow. Seventy-five hours later, at 4:54:37 P.M., Houston time, December 14, 1972, they left the lunar surface and rendezvoused with America for an uneventful last journey home.

At 1:24:59 Houston time on the afternoon of Sunday, December 20, 1972, Apollo 17 splashed down in the Pacific four miles from the carrier Ticonderoga. Counting from Apollo 8’s launch on December 21,1968, the first age of lunar exploration had lasted exactly four years.

But what was the real meaning of Apollo? What did it symbolize? What were we after?” For a few short years, Apollo was almost like a Renaissance, Petrone thinks, but nobody wants to confront that kind of possibility now—to do so would make the nation recognize how much it abandoned so casually.