Failure Is Not an Option

by Gene Kranz

  The crew continued the close-out, terminating the command module battery charge. During the previous sleep period, an alarm monitoring pressure in a hydrogen tank had awakened the crew. After considerable debate in the MCC, we did not reset the alarm out of concern that it might inadvertently trigger again and wake up the crew. As a result, a cryo pressure warning indication was illuminated in the spacecraft and also on Sy Liebergot’s console. During the translunar phase we were in continuous voice and data communications, so Sy intended to stand watch over the pressures from the ground during crew sleep.

  Liebergot was my EECOM, having moved up to the front line during Apollo 8. Now, after a year’s experience, he was considered a veteran controller. He had a second glitch he was working. The telemetry gauge in oxygen tank 2 had been reading normal at 80 percent through the mission, then during our shift the gauge went through four rapid up-and-down cycles, finally failing and sticking at a constant reading of 100 percent. We no longer had a valid reading from the sensor.

  Cryogenic oxygen and hydrogen mixed and reacted in the three fuel cells in the service module to provide electrical power. The reaction also provided pure water used for drinking and for cooling the CSM systems. The only other source of power to the command module was the three reentry batteries, normally used only for the final two hours of the mission. The oxygen and hydrogen, maintained in a liquid state at temperatures below-300 degrees Fahrenheit, were stored as liquids in spherical tanks insulated by a vacuum between the outer and inner walls. As the mission progressed, the oxygen and hydrogen went through a progressive change from a liquid to a gas.

  At the time of launch the cryogenics in the service module tanks were a dense super-cold liquid, but now, two days into Apollo 13, the cryos were a thick soupy vapor, part liquid and part gas. Fans were located internal to the cryogenic hydrogen and oxygen tanks. The fans were periodically activated by the crew, at the request of the MCC, to stir up the mixture and allow precise tank quantity measurements. Heaters were located in the tanks to raise the tank pressure. The heaters could be activated either automatically or manually by the crew.

  Sy Liebergot, wrestling with the oxygen pressure management problem and hoping to avoid an alarm during the sleep period, decided to request a cryo tank stir prior to sleep. The stir request was passed to the crew, with Swigert acknowledging the request. As Swigert started the stir at 55:53, Liebergot focused his attention on the TV monitors displaying the fuel cell currents to nail down the exact time the stir started.

  (What we could not know at this time was that a design flaw existed in the heater circuit of the cryogenic tanks. During pre-launch testing, the heater thermostat switch closed and, due to the design flaw, the Teflon insulation on the wiring internal to the tank was damaged. When the tank was serviced for the mission, the bare copper wires in the tank electrical system were submerged in liquid oxygen. Two days after liftoff two of the three conditions for an explosion existed, gaseous oxygen and damaged tank insulation. All that was required to initiate an explosion was a spark.)

  Nothing happened for sixteen seconds after Swigert started the cryo stir. Then, inside tank 2, a spark jumped between the wires of the heater circuit. The pressure in the tank rose rapidly. Preoccupied with moni toring the fuel cell currents, Sy Liebergot did not notice the oxygen flow measurements on all three fuel cells fluctuating slowly for eighteen seconds. Then the pressure in oxygen tank 2 began to rise rapidly, but failed to set off a high-pressure alarm in the command module or at Liebergot’s console because the cryo pressure alarm had been disabled for the crew sleep. The tank pressure continued its upward climb, then dropped rapidly. The temperatures in the spherical tanks began to rise rapidly. One minute and fifty-three seconds after the stir began, there was a three-second telemetry data loss. When the data returned, the tank 2 pressure read 19 psi, temperature +84 degrees Fahrenheit. The normal pressure reading is 865-935 psi.

  The time was now 55 hours 55 minutes and 04 seconds from launch.

  Like rolling thunder, my voice loops came alive: “Flight, we’ve had a computer restart.” Then in the blink of an eye, Swigert said, “We have a problem.” Then other controllers chimed in with bad news. At this point Lovell uttered the ominous words: “Okay, Houston, we have a problem!” In both the MCC and on board the spacecraft, voices were normal, but heart rates had picked up. Seconds later Haise reported, “Right now, Houston, the voltage is—is looking good. And we had a pretty large bang associated with the Caution and Warning.”

  In the MCC, you can’t see, smell, or touch a crisis except through the telemetry and the crew’s voice reports. But you can feel some instinct kicking in when something very wrong is going on. By the time I heard Lovell’s report, three controllers had related problems. I was wondering which problem Lovell was reporting, as he started relaying the long list of warning indications from the spacecraft displays. The reports and our experience indicated an electrical glitch. I believed we would quickly nail the problem and get back on track.

  I was wrong.

  A crisis had begun. Events followed in rapid succession, escalating and complicating the problems as the crew’s situation became increasingly perilous. It was fifteen minutes before we began to comprehend the full scope of the crisis. Once we understood it, we realized that there was not going to be a lunar mission. The mission had become one of survival.

  The reports continued, but nothing made sense. Each controller stared incredulously at his display and reported new pieces to add to the puzzle. It took extra seconds sorting out what was real and credible. It appeared we were losing our oxygen and with it the fuel cells, the major source of power. When that happened we would lose control of the main propulsion system. Nothing remotely like this had ever happened in simulation.

  As we watched the command module’s life-sustaining resources disappearing, like blood draining from a body, the voices of the crew were unbelievably calm and restrained. It was as if they were reporting something that was no big deal. From all sides of the cockpit, Haise, Swigert, and Lovell were continuing the dialogue, giving us the cockpit meter readings and warning light indications.

  I had heard about the fog of battle, but I had never experienced it until now. The early minutes were confusing; all reports and data were suspect. Small firefights occurred as individual problems were corrected, but we had no sense of the big picture. With both electrical buses in an undervoltage condition, the crew was working independently of the control team to restore power to the craft. We were seconds behind them, slowly responding.

  I remembered the call from INCO (instrumentation and communications), Gary Scott’s call, that the antenna had switched beam width at the exact time of the power problem. I became convinced that we had an electrical short caused by another antenna glitch. Again I took the wrong fork in the road, believing we would be back on track shortly.

  Five minutes after the event, the significance of the crew’s words, “We had a pretty large bang . . .” hit me. GNC Buck Willoughby, unflappable, started speaking to me slowly, evenly, and without a hint of emotion, “Flight, have the crew verify that the Quad D helium valves are open. I suspect that the big bang shocked the valves shut, cutting off fuel to the attitude thrusters.” Buck’s call started me down a different path. On Apollo 9, I was flight director when the pyrotechnic shock occasioned while separating the CSM from the Saturn S-IVB booster closed the fuel valves. That gave us a few bad moments then. The bang heard by the 13 crew must have been awfully solid to do the same, closing the propellant valves. From this moment on, I proceeded more deliberately and methodically. We were five minutes into the crisis.

  CapCom Jack Lousma, frustrated, came up on the loop. “Flight, is there any kind of lead we can give them? Is it instrumentation or have we got real problems or what?” Lousma echoed everyone’s feelings. We were making no progress, virtually every controller still had problems, but no one could see a pattern in all this. It was like living a bad dream, with every event taking p
lace in slow motion. The frustration of the crew and controllers was starting to creep into their voices. Everything we knew about our spacecraft, all that we had learned about the design, precluded the kind of massive failures we were seeing. The data told us we were looking at multiple simultaneous failures. Two, possibly three fuel cells were down, both oxygen tanks depleted, and we had an undetermined attitude control problem that was pushing the two spacecraft around. Soon we would lose power. When that happened, we would lose everything.

  The teamwork in the MCC under a crisis is spectacular. While Liebergot, Lousma, and I worked the electrical options with the crew, the remaining controllers were making their inputs to the CapCom, correcting their smaller problems. While sensing the urgency of the electrical problems, they tended their own business, protecting their systems and giving crisp, brief reports so as not to disturb or aggravate the resolution of the main problem—whatever it was.

  INCO Gary Scott watched the antenna signal strengths like a hawk. He knew that the crew did not have time to point and select antennas. Gary recommended a fallback to the less powerful but adequate Omni antennas. There are four Omni antennas on the spacecraft. Through the critical first hour, until help arrived, he called out each antenna switch, protecting this vital link as the docked CSM and LM drifted out of control and were pushed around by some force we couldn’t identify. If he had missed once, we would have lost communications, diverting the attention of crew and control team from critical tasks. Scott, like many others, made hero category by his patient, timely, undistracted management of the data stream while everything else was falling down about my team.

  It was now ten minutes into the crisis; all the bosses had gone home after the crew’s TV show. I needed to notify top management that we had a hell of a problem on our hands and that we didn’t fully understand what it was. Turning to Lunney, I asked him to call Kraft. Glynn handed me the phone as Chris’s wife, Betty Ann, answered. In response to my request she explained that he was in the shower. I said, “Betty Ann, get him out, I need to talk to him.” When a still-dripping Kraft got on the phone, I told him that we had a major electrical problem and that I believed we had lost one or more fuel cells. I concluded on a somewhat desperate note: “Chris, you better get out here quick; I think we’ve had it!”

  GNC and GUIDO, Willoughby and Will Fenner, had been quietly watching the crew struggle to control the spacecraft attitude and avoid “gimbal lock.” This grave problem would come about if the rings that support the whirling wheels of the gyroscope all aligned in the same position. We would then no longer have a usable reading from the gyroscopic platform. In gimbal lock we would be unable to maneuver or point the spacecraft. We would be literally adrift in space until the crew took a fix on certain stars to realign the gyros, much in the way a nineteenth-century sailing ship figured out its position. Every time the crew got close to the danger point, Willoughby, in a hushed but forceful voice, would call, “Flight, they are getting close to gimbal lock.” Lousma would advise the crew, who then used the CSM hand controller and attitude jets to maneuver away from disaster.

  The team was now functioning well; we were fourteen minutes into the crisis, fighting a delaying action until we figured out what was going on and what to do about it. Most of the problems seemed to rest on Liebergot’s shoulders. He was responsible for the systems needed to sustain life, power, water, oxygen, and pressure. But no matter what we tried, we were unable to stanch the hemorrhage of the fuel cell oxygen reactants.

  Then, abruptly, all the pieces of the puzzle came together. Lovell reported, “It looks to me, looking out the window, that we are venting something.” Then with emphasis he said, “We are venting something out into the—into space—it looks like a gas!” A shock rippled through the room as we recognized that an explosion somewhere in the service module had taken out our cryogenics and fuel cells. The controllers felt they were toppling into an abyss. Needless to say, the lunar mission was now a NoGo. The only thought on my mind was survival, how to buy the seconds and minutes to give the crew a chance to return to Earth.

  Now I was damn angry that I had wasted fifteen precious minutes by not assembling the pieces earlier. I should have seen it. Somewhere, somehow, an oxygen tank exploded and it caused a lot of collateral damage. The feeling of self-reproach passed quickly; I became icy cold, my mind reaching out for options as my training kicked in.

  Our objective from here on was survival. The crew’s only hope was Mission Control. My team had to start the turnaround. With two flight controller teams in the room, the level of chatter was distracting. My team needed to get back on the voice comm and get focused. I finally took charge. Standing up I yelled across the top of the consoles, “Okay, all flight controllers, cut the chatter. I want every member of the White Team to settle down and get back on the voice loops—the rest of you shut up!

  “Now, let’s everybody keep cool. The LM is still attached, the spacecraft is good. So if we need to get back home, we have the LM to do a good portion of it with.

  “Let’s make sure that we don’t blow the [remaining] command module electrical power with the batteries, or do anything that would cause us to lose fuel cell 2. We have to keep the oxygen working and would like to save the attitude control propellants. We are in good shape to get home.

  “Let’s solve the problem, team . . . let’s not make it any worse by guessing.”

  The team focused on keeping the crew alive and finding a way to get them home. Our determination was evident as we calculated the limited resources available in the damaged spacecraft. For the moment the power and the oxygen in the CSM could keep the crew alive but the LM was ultimately the only safe haven, even though it had been designed to accommodate only two men for two days.

  I knew I had to move quickly to stabilize the situation and then hand over the remnants of the mission to Lunney’s team. I wanted time to review all the data. I had the absolutely chilling fear that I had missed something important. I hoped that some fresh minds might pick up on it. I wanted to get the White Team off-line, get them together in a quiet corner, nail down the cause, and then start on a plan to rescue the crew. We were the lead team. It was our responsibility to take over management of the crisis.

  My console was a mess, littered with schematics, procedures, the console log, and cigarette butts. Lunney’s team was scurrying around the room preparing for handover. Clint Burton, Liebergot’s replacement, nervously awaited his turn in what had become the hot seat. Ed Fendell, who managed communications, joined Gary Scott at the console. Together they would keep up the communications, the key to an orderly transfer to the lunar module. Fendell had been at home and had just happened to have the radio on. He heard the news, jumped in his car, and came in. Racing his Corvette through the back streets of Clear Lake, Fendell arrived in a cloud of dust and parked in the middle of the exit lane. He joined in the battle with Scott, making sure that communication with the crew would be maintained without interruption throughout the crisis. I was glad to see him. I did not know how much longer Scott could continue running solo and pitching a perfect game with the communications.

  Kraft arrived as we were starting the second phase of the power-down of the CSM. Liebergot signaled the next phase of the withdrawal with a simple suggestion. “Flight, I think we better get going in powering up the LM. We’re running out of time.” He then gave Lousma the call to have the crew secure the command module entry oxygen system, a small oxygen bottle used during the final two hours of the mission. We were putting together a lifeboat; what did we need to make it work?

  Kraft plugged into my console. I glanced up momentarily and said, “Chris, we’re in deep shit.” Moments later, Liebergot began to lay out the bad news, the whole nine yards: “Flight, I hate to tell you this, but I think we’ve lost fuel cells 1 and 3.” I nodded, still thinking that maybe fuel cell 2 and one of the oxygen tanks might be salvageable and could be added to our get-home resources.

  Lunney had been down in the Trenc
h reviewing the get-home options. At the time of the explosion, Apollo 13 was 200,000 miles from Earth, 45,000 miles from the surface of the Moon. We were entering the phase of the mission where lunar gravity becomes stronger than Earth’s gravity; we call it “entering the lunar sphere of influence.”

  When Lunney came back up to the console, Kraft stepped down from his position behind me. In a hushed tone, Glynn said, “I had the Trench look at maneuvers with ignition about three hours from now. We have two basic options, a direct abort and one going around the Moon. The fastest direct abort gets us home in thirty-four hours. We fly in front of the Moon but we have to jettison the LM and use all the main engine fuel. We have several options that fly around the Moon. The best one takes two days longer, but we don’t use the main engine and we can keep the LM.” We rapidly went through the mathematics; the lunar module was good for two crewmen for two days. A quick estimate using the LM powered-down checklists and taking the path around the Moon left us at least thirty-six hours short on battery power.

  Windler, the leader of the Maroon Team, now joined us at the console. He believed the shortest and fastest path back to Earth was the best. He seemed to favor the direct abort. Lunney and I disagreed. I said, “I don’t want to jettison the lunar module. We haven’t nailed down the exact cause of the explosion or the extent of the damage. The main engine or its control systems may have been damaged. We need more time to work out the procedures for the return.”