”This Is Mission Control"

By CHRISTOPHER C. KRAFT, JR.

The last Apollo flight to the Moon has been called “the end of the beginning”. It represented more than just the end of a program to me. It brought to a close a phase of my career. Apollo had become intimately interwoven in the fabric of the waking hours of my life and often caused the remaining hours to be fewer than they should have been. My first involvement with the program had occurred at Langley Field, Va., 11 years before the Apollo 17 flight. During those formative years of the lunar program I was faced with the challenge of flying Mercury, and of necessity my commitment to Apollo could not assume the proportions it would in later years. Only twenty-three days before my first Apollo meeting at North American Aviation, we were flying Friendship 7 and John Glenn on the country’s first manned orbital flight.

In those naive early days I had no idea I would be charged with the responsibility not only for flight operations but for managing the computer software programs that would be used for landing two astronauts on the Moon and returning them to Earth. Although in 1962 we had decided we were going to the Moon, we had yet to figure out how we were going to get there and return, let alone determine the equipment, facilities, and personnel we would need. Many difficult hours were yet to be spent in conference rooms, visiting contractor plants and test sites, and waiting at airports. I had yet to experience the frightening experience of disarming an angry young man with a gun on one of many flights to Cape Kennedy. The future held both periods of despair and frustration and those exciting and satisfying moments when we flew that were to make it all seem worthwhile. Now, with Apollo 17, it was coming to an end. I found it difficult to accept the finality of that landing on December 19, 1972, near the USS Ticonderoga in the Pacific Ocean. The challenge would never again be quite the same. Apollo was like an intoxicating wine and certainly the last of the vintage.

VIGILANCE AND JUDGMENT

“The accomplishments of this last Apollo mission and the successes of the previous Apollo flights were the result of the dedicated efforts and the sacrifices of thousands of individuals.” I have difficulty recollecting how many times I stood on the platform at Ellington Air Force Base welcoming the returning flight crews and heard those words repeated. But they are nevertheless quite true. The people in Houston were with their astronauts each step of the way. The interchange between Mike Collins, serving as the CapCom (capsule communicator), and Bill Anders as Apollo 8 orbited the Moon clearly demonstrated this feeling. Mike called Apollo 8, saying “Milt says we are in a period of relaxed vigilance”. Bill came back with “Very good. We relax; you be vigilant.” They came to rely on the controllers, as they well knew their very lives depended on their vigilance and judgment. Mike later put it well in his book, Carrying the Fire. He writes of the Gemini 10 reentry and their reliance on “Super Retro” John Llewellyn. Mike says that they knew if they made a mistake John would be so angry that he would stick up his strong Welsh arm and yank them out of the sky. John’s dominant personality is illustrated by the time he was coming on duty for his shift in the Control Center and, finding his parking space taken, he simply parked on the walk next to the door rather than waste time looking. Like his compatriots, John was thoroughly dedicated. His type is at its best when fighting wars or flying missions.

Many individuals were involved in the building and testing of the spacecraft and its systems, but once given the spacecraft and the necessary facilities and equipment, the Apollo Operations Team was charged with the awesome responsibility for the accomplishment of the mission. This team was composed of hundreds of individuals - government and contractor personnel, as well as representatives of the Department of Defense and of foreign nations such as Australia and Spain. Each team member had been carefully selected and subjected to countless hours of training and simulations; each had also participated in Mercury, Gemini, or Apollo testing and flight operations. Time and time again, these young men had to rely on their technical knowledge to assess the unexpected and determine the right course of action. The “luck” the Operations Team had in overcoming adversity is exemplified by the words of University of Texas football coach Darrell Royal: “Luck is what happens when preparation meets with opportunity”. The luck of the Operations Team was the result of thorough and careful planning and training and the development of both people and procedures.

Thinking back over the events of the past years, I realize the Operations Team was always prepared when the opportunity presented itself. I’ll certainly always remember their performance on Apollo 11. It takes an awful lot of events all going right to get you to the Moon, let alone return. It was our first attempt at the landing and we had somehow, incredibly, reached the point where we were starting the descent for the landing. Thus far, all had gone astonishingly well. The first phase of the firing of the lunar module engine went well as the descent started; and then, approximately five minutes after ignition, the first of a series of computer alarms was received via telemetry in the Mission Control Center and was also displayed to the crew onboard the lunar module Eagle. I was responsible for the software in that computer, the logic that made it all work. You can imagine the thoughts racing through my mind: Had we come all this way for naught? What was wrong? The flight controller responsible for assessing the problem, 27-year-old Steve Bales, was faced with an immediate decision: Should we continue the descent or initiate an abort? An abort meant there would be no landing for Apollo 11: we would have to try again. When Flight Director Gene Kranz pressed him for his answer, young Mr. Bales’ response was the loudest and most emphatic “go” I have ever heard.

But it wasn’t over yet. The lunar module was under automatic control as it approached the surface. Neil realized that the automatic descent would terminate in a boulder field surrounding a large rim crater. He took over control of the spacecraft and steered the Eagle toward a smooth landing site. The low-level fuel light for the engine came on, indicating about enough fuel for only 116 seconds of firing time on the engine. With 45 seconds of fuel left, Eagle set down with a jolt and we were there.

A LIGHTNING STRIKE

I could recall any one of hundreds of incidents that have occurred over the years as we flew Apollo. Launch has always been an uneasy time for me, and I always looked forward to successful separation from the booster. When one adds to this an apprehension caused by bad weather over the Cape, I become even more concerned. It turned out that all of the elements were present for Apollo 12. The launch was made into a threatening gray sky with ominous cumulus clouds. Pete Conrad’s words 43 seconds after liftoff, electrified everyone in the Control Center: “We had a whole bunch of buses drop out”, followed by “Where are we going?” and “I just lost the platform.” The spacecraft had been struck by lightning. Warning lights were illuminated, and the spacecraft guidance system lost its attitude reference.

The spacecraft was still climbing outbound, accelerating on its way to orbit. There was not much time to decide what should be done. The crew was given a “go” for staging and separation from the first stage of the Saturn V launch vehicle, Within seconds, John Aaron, the CSM electrical and environmental systems engineer, found what had happened. Pete was asked to switch to the secondary data system so that telemetry would show the status of the electrical system. The crew was then asked to reset the fuel cells, which came back on line, and Apollo 12 continued on its way into orbit. Additional checks were made of the spacecraft electrical system and a guidance reference was reestablished. Apollo 12 went on to the Moon.

A chapter of this book is devoted to Apollo 13. As I moved up in the organization, I reluctantly relinquished the job of flight director. But there were many well qualified young men to assume this responsibility. My faith in their abilities was confirmed by their actions during this epic flight. Following the successful return of the Apollo 13 crew, the performance of the Operations Team was recognized with the presentation of the Medal of Freedom by the President of the United States to Sig Sjoberg, my colleague through all the tribulations of Mercury, Gemini, and Apollo.

Docking was another major hurdle that had to be overcome if we were to make it to the Moon. Normally, it went well but I always breathed easier when it was behind us. There had been no major docking problems in the program until Apollo 14. After five unsuccessful attempts by Al Shepard and his crew, we still had not made the initial docking with the lunar module. Previously we’d always had a docking probe and drogue available in the Control Center, as well as experts on the system, but now there were frantic calls for assistance and the absent docking system had to be hurriedly located to help understand what might be going on thousands of miles out in space. Procedures were worked out and another attempt proved successful.

REPROGRAMMING IN FLIGHT

The next Apollo 14 problem occurred just prior to the final descent for landing at Fra Mauro. An abort command was received by the lunar module’s guidance computer. Had the abort command been initiated, it would have separated the ascent stage from the descent stage and terminated the landing. The descent had to be delayed; and, as Al Shepard and Ed Mitchell orbited the Moon, the ground valiantly tried to determine the cause of the problem. It was isolated to one set of contacts of the abort switch on the instrument panel. Recycling the switch or tapping on the instrument panel removed the signal from the computer. A computer program was developed and verified within two hours by the Operations Team and inserted manually into the computer, allowing the computer to disregard the abort command. The unexpected came again within minutes. As the crew started the descent to the Moon, the altitude and velocity lights of the computer display indicated that the landing radar data were not valid. This information provided essential updates to the computer. Flight Controller Dick Thorson made a call to recycle the landing radar circuit breaker. The crew complied. The lights were extinguished and the necessary computer entry update was made at an altitude of about 21,000 feet. Apollo 14 and Al Shepard’s and Ed Mitchell’s climb almost to the top of Cone Crater are now history.

There were occasions when the problems that came up did not require an instant decision but rather resulted in long hours in conference in Mission Control. For example, on Apollo 15, the flight of Endeavour and Falcon, as the spacecraft traveled from the Earth to the Moon, the service propulsion system developed a problem. This is the system that is required to place the spacecraft in orbit around the Moon and on its trajectory back to Earth. Needless to say, this was a critical system. A light had illuminated showing that the engine was firing while it obviously was off. This had to be caused by a short in the ignition circuitry. Had this circuit been armed while the short was present, the service propulsion engine would have fired. The Operations Team, working with Don Arabian, a legend in his own time, and Gary Johnson, an excellent young electrical engineer, isolated the short to one of two systems. A test firing was initiated by the crew to verify that the short existed on the ground side of one of two sets of valves. Procedures were then developed by the ground, working with the flight crew, and the mission continued.

LONG-DISTANCE SOLUTIONS

Apollo 16 had its unique problems and one was a major one of the instantaneous and serious variety. Just after separation of the CSM from the LM, prior to initiating final descent for the landing, a maneuver was to be performed by the command and service module Casper to circularize its orbit around the Moon. Preparations for the burn went well until a check was made of the secondary yaw gimbals. These gimbals controlled the direction of thrust in yaw plane for the service propulsion system, a system that was essential to insuring that the astronauts could get out of lunar orbit. The gimbals appeared normal until the motor was started and then they exhibited rapidly diverging oscillations. The two spacecraft were asked to rendezvous; and Jim McDivitt, the Apollo Spacecraft Program Manager, met with Bob Gilruth and me to tell us that it appeared to him that the mission would have to be terminated.

Another meeting in an hour was scheduled to review the bidding. By the time we had the second meeting, the Operations Team, through extensive testing and simulations, determined that the oscillations would have damped and the secondary servo system was safe to use. John Young and Charlie Duke proceeded with the landing, as I reflected on the phenomenal capabilities of a group of young engineers who had solved a problem of a spacecraft 240,000 miles away from Earth.

Apollo 17, the final mission to the Moon, clearly demonstrated the maturity of the Operations Team. For the first time, a manned launch was made at night. A landing was made in the valley of Taurus-Littrow, the most difficult of any of the Apollo landing sites. The spacecraft performed in an outstanding fashion, and there were no major problems. Minor ones that did occur were handled without difficulty. The problems encountered were all overcome due to the careful premission preparation, rigorous testing, planning, training, and hours and hours spent simulating critical phases of the mission with the flight crew. These simulations prepared the controllers and the crew to respond to both normal and abnormal situations. Their record speaks for itself on the adequacy of the training. This was not brought together overnight, and in 1962 we were a long way from Taurus-Littrow.

The basic flight-control concepts used for Apollo were developed by a small group of people on the Mercury Operations Team. In 1958, under the leadership of Robert R. Gilruth, the Space Task Group had been given the fantastic responsibility of placing a man in orbit around the Earth. Those few young men who assumed this task did not have any previous experience on which to rely. It had never been done before. What they did have was the willingness to tackle any job, and a technical capability that they had attained through an apprenticeship in what I consider to have been the Nation’s finest technical organization, the National Advisory Committee for Aeronautics. Other members of the Mercury Operations Team had experience with aircraft development and flight testing with the Air Force and Navy or with major aircraft companies, both within this country and in particular with AVRO of Canada. That country’s cancellation of the CF-105 with its attendant effect on the AVRO program proved to be a blessing to the United States space program. Many fine engineers came to work as members of the Space Task Group at Langley. Jim Chamberlin, John Hodges, Tecwyn Roberts, Dennis Fielder, and Rod Rose, to name a few. The operational concepts that were developed by this cadre on Mercury were improved as experience was gained on each flight. As the Operations Team assumed the responsibility for flying Gemini, the concepts were further developed, expanded, and improved. There were many essential steps that had to be taken to get to the Moon. For the Operations Team, Gemini was one.

Only a small group of people were involved in Mercury operations. When the team was given the responsibility for flying Gemini, and with the Mercury flights continuing, the organization had to be expanded. A conscious effort was made to bring young people into the organization. With an abundance of recent college graduates, the team took on a young character. The additions brought with them the aggressiveness, initiative, and ingenuity that one finds in the young engineer. They did not all come from major colleges; there were graduates of Southwestern State College in Oklahoma, Willamette University in Oregon, San Diego State College, Texas Wesleyan College, and Northeastern University in Boston, to name a few. A large contingent of officers was also made available by the U.S. Air Force and this group provided excellent support. I came to rely on these young people and I can honestly say they never let me down.

AN ADVANCED COMPUTER COMPLEX

As the team was being built, the facilities and equipment were also being defined, developed, constructed, and brought on line. The Mercury flights were directed from a control center at Cape Canaveral, Fla. In 1962, the Space Task Group moved to Houston to form the Manned Spacecraft Center. The construction of the Mission Control Center in Houston, designed to accomplish the lunar missions, was started in 1962. Thirty-six months later it was to be used to control Jim McDivitt’s and Ed White’s flight in the Gemini IV spacecraft. Its full capability was not used for Gemini, however, as much work still had to be accomplished. One of the most advanced computer complexes in the world had to be integrated with a global tracking network. Tracking and telemetry data had to be relayed from stations in Australia, Spain, the Canary Islands, Guam, Ascension Island, California, Bermuda, Hawaii, Tananarive, and Corpus Christi. Tracking ships were built to provide additional communication coverage in ocean areas. Special Apollo Range and Instrumentation Aircraft (modified Boeing KC-135 jets) were deployed around the world.

All this was being done concurrently with the evolution of operational concepts. During the Mercury and Gemini flight programs, teams of flight controllers at the remote tracking stations were responsible for certain operational duties somewhat independent of the main Control Center. The advantages of having one centralized operations team became more apparent, and for Apollo, two high-speed 2.4-kilobit-per-second data lines connected each remote site to the Mission Control Center in Houston. This permitted the centralization of the flight control team in Houston. Provisions were also made to tie into the Control Center, through a communications network, the best engineering talent available at contractor and government facilities.

An array of specialists manned the consoles during an Apollo mission. Key numbers above identify the locations of flight controllers. 1 was the Booster Systems Engineer, responsible for the three Saturn stages. 2 was the Retrofire Officer, keeping continuous track of abort and return-to-Earth options. 3 was the Flight Dynamics Officer, in charge of monitoring trajectories and planning major spacecraft maneuvers; he also managed onboard propulsion systems. 4 was the Guidance Officer, who watched over the CSM and LM computers and the abort guidance system. In the second row, 5 was the Flight Surgeon, keeping an eye on the condition of the flight crew. At 6 was the Spacecraft Communicator, an Astronaut and member of the support crew, who sent up the Flight Director’s instructions. (He was usually called CapCom, for Capsule Communicator, from Mercury days.) 7 concerned CSM and LM systems, including guidance and navigation hardware; and electrical, environmental, and communications systems. After Apollo 11, all communications systems were consolidated as a separate task. On the next row in the middle was 8, the Flight Director, the team leader. 9 was the Operations and Procedures Officer, who kept the team - in and out of the Center - working together in an integrated way. 10 was the Network Controller, who coordinated the worldwide communications links. 11 was the Flight Activities Officer, who kept track of flight crew activities in relationship to the mission’s time line. 12 was the Public Affairs Officer who served as the radio and TV voice of Mission Control. 13 was the Director of Flight Operations; 14 the Mission Director from NASA Headquarters; and 15 the Department of Defense representative. During activity on the lunar surface an Experiments Officer manned the console at 1 to direct scientific activities and relay word from the science team.

As engineers from the Goddard Space Flight Center were intently determining the requirements for this ground communications network, building and installing equipment, and laboriously testing and verifying the network’s capabilities, engineers in Houston, led by a young Air Force officer, Pete Clements, and a fine young engineer, Lynwood Dunseith, were feverishly working to integrate the computer complex and Control Center displays with the network. The critical parameters and limits that had to be monitored in flight needed to be defined; the necessary sensors for measuring the parameters needed to be incorporated in the design of the spacecraft; and rules for utilizing the measurements needed to be developed. But it was not only a question of ensuring that the right measurements were made. Spacecraft and subsystem design also had to have the redundancy and the flexibility needed to overcome failures and contingencies as they arose. And time was relentlessly marching on. Testing of the spacecraft revealed new problems, and new techniques and procedures often had to be developed to avoid potential difticulties in flight. Programs had to be developed for operating the spacecraft and Control Center computers, and the programs had to be verified, tested, and incorporated in the computers. The end of the decade moved closer each day. The complexity of the spacecraft and launch vehicle was exceeded only by the complexity of a worldwide ground-control system.

Then came January 27, 1967, and the AS-204 fire, a day I’ll never forget. I was at the console in Houston monitoring the test at the Cape, together with a group of flight controllers. We thought we had considered every eventuality, and now we were struck down by an event that did not occur in space but happened during a ground test. There were no excuses that could be offered but, out of the despair of the fire, there came a rededication to the successful accomplishment of the goal and an intensified effort on the part of every individual.

The Operations Team had many functions not associated with testing and checking out the spacecraft and controlling the mission. These functions were nevertheless essential to success. One was recovery operations. Recovery techniques for the spacecraft and the crew had to be worked out in conjunction with the Department of Defense and the U.S. Navy. Bob Thompson organized and led this effort during Mercury and Gemini. The organizational team he established provided the same excellent recovery support for Apollo as it had for Mercury and Gemini.

MANEUVER TARGETING

The team also developed the techniques for flying the spacecraft and controlling its trajectory. It had the primary responsibility for developing the programs or logic used in the computers onboard the lunar module and the command and service module as well as those in the Control Center. Except for rendezvous maneuvers, the Control Center was the only source of maneuver targeting; that is, determining the exact magnitude, direction, and the time for executing each flight maneuver. Bill Tindall, a truly outstanding engineer, contributed significantly to this effort. Operations were planned in detail before a flight. Plans were based both on everything working properly and on the “what if” situations that might occur. The “what if” situations could not be carried to the point of actually reducing reliability by introducing confusion or complexity into the system. This was quite often a fine line to walk. Techniques also had to be developed for monitoring all essential systems during critical mission phases. The procedures, the techniques, the personnel, and an organization all had to be defined and developed, a task of no small magnitude. Each landing demonstrated how well the task was performed. Apollo 12 was a classic example, with an incredible pinpoint landing some 600 feet from the Surveyor spacecraft that had previously landed on the Ocean of Storms.

To conduct operations for the flights, four complete flight-control teams were organized and used for all Apollo missions. Each team was headed by a flight director; Gene Kranz, Cliff Charlesworth, Glynn Lunney, Gerry Griffin, Pete Frank, Milt Windler, Neil Hutchinson, Phil Shaffer, and Chuck Lewis were all assigned this responsibility during various phases of the program. To simplify the overall training program, each team was assigned different events or activities. The individuals on each team could thus devote their full attention and energy to developing proficiency in accomplishing a few things, as opposed to having to cover an impossible spectrum.

The team was responsible for developing the mission plans to demonstrate the capability of the spacecraft, the systems, and the team to land a crew on the Moon. A series of unmanned developmental flights was planned with well defined objectives to be demonstrated on each flight. Apollo 7, the first manned flight, occurred in October 1968, and the first flight to the Moon, Apollo 8, occurred two months later. Even while Apollo 7 was flying, the Operations Team was performing simulations and training for the Apollo 8 mission. As Apollo 8 was flying, training and simulations were being conducted for Apollo 9, the first Earth-orbital flight of the LM and CSM in March 1969. The next step, Apollo 10 - a dress rehearsal for the first landing - was taken in May 1969. On this flight, on the far side of the Moon, a fuel cell was lost and taken off line. The team had trained for this contingency and reacted accordingly.

TRAINING CREWS AND CONTROLLERS

Astronaut training and development of the flight plans and crew procedures were directed by Deke Slayton. He accomplished these tasks in an outstanding manner. The training that Deke provided the crews, as well as the training provided the flight controllers, gave them the capability to react to the unexpected. Quite often it resulted in unique training devices and equipment. The zero-gravity environment was simulated by using a modified KC-135 aircraft that flew parabolas, thus creating 20 to 30 seconds of weightlessness. A neutral buoyancy water tank was also used to simulate the weightless environment. The unique Lunar Landing Training Vehicle (LLTV) was developed to train the astronauts in controlling the lunar module during the final phase of its descent and landing. The test flights of the LLTV, for example, saw the successful emergency ejection of three pilots - Joe Algranti and Stu Present, research pilots, and Neil Armstrong, the commander of the first lunar landing mission - because of vehicle failures. Bob Gilruth and I both believed that flying this craft was more hazardous than flying the actual lunar module.

Simulators also had to be developed to provide training for the flight crew in the operation of the spacecraft. These simulators were tied in with the Mission Control Center so that an integrated training could be accomplished with the flight controllers. These simulations allowed the flight crew to train realistically for all phases of the mission, including the landing itself. Unique display techniques were used with actual models of each landing site. The models allowed the crew to gain familiarity with the terrain and recognizable landmarks. Detailed lunar maps that were based primarily on data provided by the NASA unmanned lunar orbit program were prepared by the Air Force Information and Charting Service and by the U.S. Geological Survey.

As the system matured after Apollo 11, greater emphasis was placed on scientific training and on ensuring that the astronauts were prepared to perform scientific experiments when they arrived on the Moon. Prominent scientists both from within the government and from universities throughout the country offered their time and talent to ensure that the crew and the Operations Team were adequately trained to perform the demanding scientitic tasks. During the mission, they also participated as members of the Operations Team. Apollo brought a new aspect to spaceflight as man on the surface of the Moon worked in conjunction with a science team on Earth that capitalized on his observations, judgments, and abilities. They assessed his comments and evaluations, and modified the science planning and objectives in real time. This was not accomplished, however, without moments of frustration and anguish during the early flights, when the acceptability of the spacecraft and its systems was yet to be proved. During the later lunar missions, the crew and the Operations Team were working with proven procedures and a proven spacecraft, and the capabilities of the science organization were effectively integrated in the performance of the missions.

As a means of saying thanks, on March 5, 1973, this group of scientists held a dinner for a number of the program and operations personnel they had worked with over the years. The events of that night clearly showed how well this relationship had developed. As late as 1969, there were very few that would have been brave enough to predict such a dinner would have ever occurred.

CONTRIBUTIONS OF FLIGHT SURGEONS

Chuck Berry and Dick Johnston and their medical personnel also played an important role as members of the Operations Team. Working with engineering personnel, they developed the monitoring techniques used to observe the critical medical parameters of man in flight. The flight surgeons’ judgment and ability to assess the astronauts’ well-being in flight as well as their confidence in the crew’s readiness to undertake each of the missions were very necessary to achieving success. In the beginning, there were some who doubted man’s capability to even exist, let alone work, in the environment of space. Chuck Berry had no such doubts and worked bard to alleviate such concerns. I do not believe that we could have gotten to the Moon without the contributions of the flight surgeons.

The Apollo Operations Team was a unique group brought together to accomplish a successful landing on the Moon and return to Earth. I do not believe that the dedication and the capabilities of these people have ever previously been duplicated, and I doubt that such a group will ever be brought together again. A great amount of preparation preceded the actual flying of an Apollo mission. The spacecraft had to be designed, built, and tested, but the group that actually flew the mission was faced with an awesome responsibility. President Truman had a sign on his desk in the White House stating that “The buck stops here”. This comment could well be applied to the Apollo Operations Team. For these young men and women, the Apollo missions were their finest hour - the truly great adventure of their lives as well as of mine.