Looking back with the help of detailed program reports and 20 years of additional experience, I view the goals, objectives, and achievements of the Surveyor program with a clearer perspective than when I was involved in its planning. Reliving Surveyor challenges and results gives me a warm feeling, for in retrospect, our team did not appreciate the engineering obstacles that would be encountered and overcome. Considering the scope of the total Surveyor effort and the new technologies required, we were very fortunate that five of the seven Surveyor spacecraft performed brilliantly.
Reports show that we did recognize spacecraft design challenges in a general way. However, in some planning documents the fact that Surveyor was to be launched with a newly developed Atlas/Centaur launch vehicle instead of an extensively tested and proven Atlas/Agena was merely mentioned in passing. Considering the problems that changes in specified performance for the new vehicle caused scientists, whose experiments had to be jettisoned because of the reduced payload, the scant reference to this problem now seems strange. At the time, the experience was almost as traumatic as if we were selecting by lot and throwing some passengers overboard at sea to save the sinking ship. The reductions in weight capacity of the Atlas/ Centaur caused compromising modifications throughout Surveyor's development, making it abundantly clear that, for all its promise of greater performance, the new hydrogen-oxygen technology barely arrived in time.
The transit portion of the Surveyor mission from launch to the Moon was similar to the cruise mode for Ranger and Mariner; by 1964 there was some confidence in our ability to perform that phase. Nevertheless, the matter of achieving a cruise mode with orientation to provide solar power and ensure a midcourse correction maneuver-another rocket firing that required all aspects of attitude orientation and its many complexities-was never to be taken lightly. Not only had Surveyor to navigate through space between Earth and the Moon, but the landing on the Moon had to be made using a  brand-new retro rocket, terminal radar systems, and modulated vernier rockets to allow the vehicle to soft-land 240 000 miles away from the humans who had designed it. The frightening part was that no one could make adjustments or do the little things that are often required to make rocket launches successful.
When I joined NASA Headquarters in 1960, Benjamin Milwitzky was already there. Ben had been a long-time NACA researcher at Langley before NASA was formed, specializing in structural dynamics and other sophisticated engineering activities. He was noted for his sharp technical skills and his meticulous attention to detail. He and I were assigned to work together on lunar flight systems and became close associates throughout the Ranger, Orbiter, and Surveyor programs. At the beginning of the Surveyor formal definition phase, Ben was named Surveyor Program Manager.
Ben's technical background in dynamics had included involvement in the design and analysis of aircraft landing gear, an area of major importance in developing a Surveyor that would land by dropping onto the unknown surface of the Moon. In addition to the direct applicability of his background to this and related engineering challenges, Ben had been well schooled in solving tough technical problems of any type. There were times when I felt his "research" approach to solving problems was at odds with our development tasks and management assignments, but hindsight clearly shows the tremendous benefits his talents, skills, and dedication brought to this undertaking.
The coordinated development of a Surveyor engineering definition was one of Ben's first tasks. Working closely with JPL, Ben and the project office established requirements for both mission and spacecraft that would be specified for bidders hoping to develop and build the spacecraft hardware. Because of JPL's commitment to Ranger and Mariner programs, both largely being built and tested in-house, we decided at the outset that Surveyor needed the participation of a prime contractor. This was not looked on with favor by most JPL officials; perhaps their laboratory background plus some frustrating experiences with contractors providing missile hardware were the reasons for their concern. Whatever the cause, they had reluctantly gone along with the strong NASA Headquarters position that a contractor would be used to develop, build, test, and support the Surveyor spacecraft.
After the project bogged down in midstream, the extent of Surveyor planning was criticized by congressional subcommittees and others. But considering how the spacecraft came out I believe it remained remarkably close to the concept envisioned during the formative stages. Actually, four concept  proposals were presented by prime aerospace contractors; the one offered by Hughes Aircraft was chosen. It was primarily the technical aspects of the Hughes proposal that resulted in its selection, for all of us, especially Milwitzky and his JPL project counterparts, were technically oriented. Much later in the program we came to appreciate the importance of other factors, as we learned several management lessons the hard way.
It is difficult to put the necessary engineering tasks and technologies in proper perspective, but the new and most significant challenge for Surveyor was the landing. The three major elements of the landing system were (1) a high-performance solid rocket motor to provide the bulk of the velocity reduction on approach, (2) liquid propellant vernier engines capable not only of varying thrust but also of swivelling to allow attitude orientation, and (3) the landing radar system, which sensed distances from vertical and lateral motions with respect to the Moon. Because the allowable spacecraft weight for Centaur was only about 2150 to 2500 pounds, the retro rocket that decelerated the spacecraft near the Moon had to be very efficient. Even with a highly efficient rocket, the landed weight of the spacecraft would only be about 650 pounds, barely enough to incorporate the power, environmental control, communications, and scientific instruments necessary to make the mission useful.
The solid propellant retro rocket designed by the Thiokol Chemical Corporation and later designated the TE-364 was chosen because, in concept, it provided high reliability and simplicity. While simple in the operational sense, solid rocket design is far from a simple matter because the margins for error are so small. For the Surveyor retro, the case had to be as light as possible, or, to put it another way, the ratio of propellant weight to total weight had to be as large as possible. Efficient cylindrical cases had been made from spiral wound fiber glass, but for Surveyor the case was made spherical because it is the most efficient shape for a pressure vessel. Fiber glass was not suitable for the spherical shape, and steel was used.
The large expansion ratio nozzle was embedded as far as possible inside the case to shorten the rocket and to save weight. This involved some experimental development, but with good design and testing the Surveyor rocket produced the highest performance ever for such a large solid rocket. It was designed to produce a vacuum thrust of 8000 to 10 000 pounds with propellant loading to suit the final spacecraft weight and landing requirements. Its burn time was approximately 40 seconds, and it produced a specific impulse of about 275 to 280 seconds.
 The three small vernier engines were also specially developed for Surveyor application by the Reaction Motors Division of Thiokol Chemical. These engines used hypergolic liquid propellants with a fuel of monomethyl hydrazine hydrate and an oxidizer of MONO-10 (90 percent N2O4 and 10 percent NO). Each of the three throttleable thrust chambers could produce between 30 and 104 pounds of thrust on command. One engine was swivelled to provide roll control to the spacecraft. The development of throttleable liquid rockets had always been a challenge because it was difficult to maintain proper fuel-oxidizer ratios and achieve reasonable performance with fixed-geometry thrust chamber and nozzle. Although the engines were small, obtaining repeatable performance and accurate adjustment was a significant engineering development.
To properly control the rocket systems, a radar altitude Doppler velocity sensing (RADVS) system was developed by the Ryan Aeronautical Company. This included a so-called marking radar, which initiated the signal to fire the main retro, and the closed-loop system, which provided signals for the operation of the vernier engines during the soft-landing. At an altitude of about 59 miles above the Moon's surface, a signal was generated by the altitude marking radar mounted within the nozzle of the main retro rocket, and 7 seconds later, at about 47 miles, ignition took place, expelling the radar unit and initiating the 42-second main retro rocket burn. At the completion of this burn and after jettison of the empty rocket case, Surveyor was close enough to the Moon to receive an excellent radar return from the surface. Operating in a closed-loop mode, RADVS sensors provided signals that were processed by the onboard computer and fed into the autopilot that controlled the three vernier rocket engines for steering and decelerating the spacecraft along a predetermined, optimum descent profile. Finally, at an altitude of about 14 feet, the vernier engines were cut off, allowing Surveyor to drop gently to the surface of the Moon, touching down at a speed of approximately 7 miles per hour. While providing the throttling of the engines to reduce the descent velocity, the radar signals also provided the information necessary to orient the spacecraft vertically and to diminish any sidewise motion relative to the surface of the Moon which might have caused a tipover on touchdown.
Sometimes we are given the impression that very large rockets like the Saturn are more difficult to design and build than small rocket systems like those employed in Surveyor. From an engineering and technology standpoint, this is not necessarily true. Indeed, the vernier retro system of  Surveyor and its closed-loop guidance using surface-sensing radar involved many technical facets that were more demanding than those required for control systems on a large booster rocket. In addition to the sophisticated technologies, the problem of weight constraints and size limitations produced additional challenges.
A further design concern for the Surveyor landing system that tended to be forgotten after the successful landings was our uncertainty about the surface of the Moon and its suitability for a landing. At the time Surveyor was being designed, theories about the composition of the lunar surface varied widely. The spectrum of opinions ranged from many feet of soft dust which would not have supported normal landing gear to large boulders and craters in such array that Surveyor could not have touched down without impaling itself or overturning.
The engineering model of the lunar surface actually used for Surveyor design was developed after study of all the theories and information available. Fortunately, this model was prepared by engineers who were not emotionally involved in the generation of scientific theories, and the resulting landing system requirements were remarkably accurate. Even with high praise for the generation of a realistic lunar surface model, however, I would be the last to say that Surveyor landings did not involve a certain amount of good luck. Indeed, photos taken at every landing site showed features within view of the cameras that could have caused catastrophic results if a landing had been made a short distance from the actual point of touchdown.
Without question, the approach and landing radar, the high-performance retro rocket system, the attitude control system, and the variable-thrust rockets required for landing involved extremely challenging engineering tasks that took somewhat longer and were more costly than initially envisioned. In retrospect, the actual development times and costs do not appear excessive, but in the 1960s, when so little was known of the entire process, estimates for the scope of the effort were far lower than they should have been.
One of the management decisions made in the development of the approach and landing system for Surveyor was to conduct simulated landing experiments on the surface of Earth with a system as nearly complete as possible. I advocated this plan, because I believed that we would seem foolish if problems occurred during landing on the surface of the Moon that might have been discovered during a simulated approach and landing on the  surface of Earth. Of course, such a simulation involved tradeoffs: the gravities of Earth and the Moon differ by a ratio of 6 to 1, the atmosphere on Earth produces aerodynamic effects for a test descent that are not present on the Moon, and rocket performance in the atmosphere is different from that in a vacuum. It was thus necessary to introduce known compromises into the engineering of the model for Earth landings. Two aspects of the drop tests which proved to be extremely valuable were (1) the requirement for exercise of every landing system component in concert and (2) the necessity for subsystem team members to work out problems together through a realistic scrimmage before the actual mission on the Moon.
In general, the plan involved simple logic: a number of tethered tests would be performed, first using a large crane and later balloons, which would allow performance testing of the radar and spacecraft controls above the surface of Earth without the danger of a crash. The final test phase would involve 1500-foot drops from a balloon in which the Surveyor landing article would actually conduct its own descent phase, including landing on the surface. Three consecutive successful landings were declared to be mandatory to meet the goals of the test. The drop tests were conducted at White Sands, New Mexico.
Early landing system tests were not successful. One of the mistakes made initially and recognized later was that the hardware used for drop testing was not of flight quality in every respect. This was frustrating and time consuming because the test hardware that failed might not have been used in the actual mission and might not have failed. In addition to hardware shortfalls, the first tests were not conducted with the discipline and rigor that would have been present had the test landings been taken more seriously. After a significant amount of difficulty, discipline was introduced through special project-like assignments. People were told in no uncertain terms that they were to conduct the test activity as if it were a real mission. Incentive awards and other means of recognizing the importance of the tests were included in the plan. The final results were good, culminating in the required number of successful drops and providing as much proof as possible that the entire attitude control rocket radar landing system had been integrated well enough to achieve landings on the Moon.
In October 1965, just a few months before the first successful Surveyor landing in May 1966, a critical review of the Surveyor project was conducted by a House Committee on Oversight. Their report expressed concerns in closing paragraphs:
While one cannot take issue with the generalities expressed in the document, I now feel that the committee's bold expectations for the project, probably encouraged by the confidence evident in our early planning documents, were perhaps inappropriate.
Seven years passed from project initiation to the final flight of the seventh Surveyor. In 1964, at the midpoint in development, technical and management problems were obvious. This was the year that the vernier engines contractor encountered such severe technical difficulties that the JPL project office terminated the contract with Reaction Motors Division (RMD), and sought an alternative source. This step was taken and the results presented to us at Headquarters as a fait accompli after acceptable progress seemed hopeless. Although upset by this precipitous action, we went along with the initiation of a new development contract with Space Technology Laboratories (STL) for replacement verniers. The gravity of the situation caused me to become personally involved, and one of the first things I did was visit both STL and RMD. It became obvious that we really were in a bind: the RMD hardware was in short supply, test results had been spotty, their manufacturing and test facilities were run down and poorly equipped (I remember describing the place as a "bucket shop" to my associates), and STL obviously needed time that we did not have to come up to speed.
As is often the case, however, the darkness was worst just before the dawn; at the time of the termination of the contract with Reaction Motors, it was true that a lot had happened without any indication of success for the rocket engines. Cancellation of the contract distressed RMD management, of course, and they were doggedly determined to carry the development efforts a step further. Their significant progress in turning the situation around (using their own funds, I might add) plus their willingness to reenter contract status on a negotiated basis were commendable. I believe RMD engineers and management officials made a remarkable recovery because of a genuine interest in the Surveyor project and because of a genuine concern for their  company's integrity. In the terse language of the House Oversight Report:
In the same year, the radar altimeter and Doppler velocity system under development at Ryan Aeronautical was experiencing severe technical problems. This system was definitely pushing the state of the art-it had to provide triggering for the main retro from an altitude of 50 to 60 miles and then provide the control signals for rocket orientation and thrust levels from approach to touchdown. All these functions had to culminate in a final sink rate of about 5 to 10 feet per second at touchdown! Looking back, it seems obvious that if such technology had already been available, helicopters would have been using it to land under poor visibility conditions. It is interesting to note that the techniques developed for Surveyor have not yet been incorporated into everyday use by helicopters, even after 20 years.
Also in 1964, two of the initial drop tests-in which Surveyor test vehicles suspended from a balloon 1500 feet above the surface of the desert were dropped to Earth-failed. In the first case, an electrostatic discharge apparently caused a failure in the release mechanism; the test vehicle was dropped prematurely and crashed. Thus, the failure was determined to be associated with the test environment only. In the second drop test in October 1964, five independent component failures were identified; some involved the spacecraft, and some were associated with test equipment. These failures prompted the effort to regroup and introduce discipline into the tests by using flight-quality hardware and better procedures.
In the first half of 1964, a nightmare period for Surveyor, other frustrations occurred. On January 30, Ranger 6 failed to operate after being launched successfully, triggering the failure review essential to recovery planning and initiation of engineering changes before the next Ranger flight. In addition, a congressional oversight committee held hearings in April on  the Ranger failures. Preparing for and participating in that 4-day "inquisition" took a lot of my time and the time of several key people at JPL.
Selection of a contractor for the Lunar Orbiter had been made in December 1963, and we were inaugurating a new project organization at Langley in addition to negotiating a contract with the Boeing Company, new to the manufacture of lunar spacecraft. Because of congressional questions about the selection of Boeing, I had several "response activities" to deal with in addition to the contract preplanning and negotiations that were going on from January through March toward a new incentive-type contract. During that period it was necessary for me to travel to Seattle for conferences with Boeing and Air Force representatives and also to meet at Langley, Lewis, and JPL to encourage good field center management arrangements for the Lunar Orbiter. In January 1964 the Mariner Mars '64 spacecraft design was frozen, and NASA quarterly reviews were held in February and May as part of our management discipline. The Mariners were to be shipped in the summer for launch in November, and close coordination was required to ensure that test results met preshipping requirements. Surveyor alone presented plenty of problems, but I really had my hands full with failure reviews, contract difficulties, overruns, and the development of plans for additional projects.
Our own Headquarters project review of Surveyor 1 initiated in March 1964 produced a number of disturbing findings and recommendations. None of these really surprised me, but the formal returns from this review added more weight to our recommendations for action. Milwitzky, Cortwright and I had been advocating for some time the strengthening of the Surveyor project activities at JPL. Because of JPL's diverse in-house project involvements, we also felt that a deputy director or general manager who had more experience with contracting and related management matters was needed to augment the director's staff. Finally, after pressure was applied for several months, the CalTech Board of Directors encouraged Bill Pickering to hire retired Major General Alvin Luedecke as Deputy Director. Luedecke had been manager of the Atomic Energy Commission for several years and was planning to leave.
Luedecke's arrival at JPL on August 1, 1964, was welcomed by those of us at NASA Headquarters, and I immediately began to work with him on what I termed "recovery planning" for Surveyor. By this time, the. success of Ranger 7 had improved NASA-JPL relationships somewhat, and General Luedecke rolled up his sleeves and addressed the Surveyor question as a major effort. Among the first things that occurred was the upgrading of the  project staff, beginning with the assignment of Robert J. Parks, then responsible for JPL s planetary projects, as the Surveyor Project Manager. Eugene Giberson, who had been the Surveyor manager, stepped down but remained a valuable member of the Surveyor team. To his credit, he recovered from the experience with knowledge and skills that were later applied in the successful management of other major projects. Additional JPL staff members were immediately assigned to the effort because Parks already had a number of systems engineers and others under his aegis; with the decision to upgrade the Surveyor team significantly, some 200 people were assigned in short order.
It is interesting to note how good men rally to worthwhile causes in times of need. Alvin R. Luedecke appeared at a very propitious moment in the history of the lunar and planetary programs. As already mentioned, he was hired with considerable "encouragement" by NASA after the need for stronger discipline in making organization assignments and dealing with contractual matters at JPL was recognized. It would be easy for a casual observer to assume that General Luedecke could have made only a minor contribution during his few years at JPL; in my view, what he did was a keystone effort that resulted in significant long-term benefits.
For one thing, during 3 years at JPL, Luedecke's many 16-hour days and 7-day weeks amounted to 6 or 7 years of effort on a normal work schedule. He was on the job in the office much of the time, but he was never away from the work, as it was his nature to spend as much time as necessary on his tasks. After getting to know this impressive man personally, I learned that he brought to JPL many years of experience in tackling tough jobs and wrestling them to the ground.
A can-do attitude was evident from his early choice of a college curriculum to his last appointment as an acting university president. When he decided in 1928 to leave the ranch and attend college, he chose to study chemical engineering, partly because he was told it was the toughest and most challenging branch of engineering available at the time. Over the years his jobs seemed to lead him into the newest and least-known regions of technology because of the same drive.
An Army Air Corps pilot officer for many years, Luedecke became a general during World War II. When the war ended, he was directly involved in nuclear energy, the very newest technology at the time. His assignments included the development of weapons, facilities, and ranges for testing, eventually leading to his selection as general manager of the Atomic Energy  Commission. From what I have determined, trying to manage that large, highly technical agency with its many critics, plus the problems of dealing with secrecy and intrigue, would have been a difficult chore in its own right. But I never understood how a general manager could survive in that environment while also reporting to a number of commissioners who were political appointees from all walks of life. General Luedecke managed to do this successfully for 6 years.
The change from nuclear energy to space was just the sort of challenge Luedecke liked to tackle, and I believe his experience, determination, and soft-spoken manner were just what JPL needed at the time. Of course his coming was not welcomed by most of the staff because of uncertainties about what might happen, but in time things settled down, as Luedecke's personalized, get-involved methods soon rallied support of his leadership. Bill Pickering took an extended trip shortly after Luedecke arrived; this gave Luedecke time to become acquainted with activities and key personnel, and precluded divisive game playing by disgruntled employees.
At NASA Headquarters it was recognized that a major upgrading of the Surveyor contract with the Hughes Aircraft Company was required. Ed Cortright personally undertook the preparation of a new incentive-type contract, working directly with General Luedecke, Hughes officials, and Surveyor contracts personnel. This was a very difficult task, partly because of the sensitivity involved in determining the status of contract activities at the time. Things were generally fouled up, and there were several loose ends that could probably be attributed to inertia: a number of technical changes had been made but never incorporated in the contract, and it was hard to tell who was responsible for what. By late 1964 about 46 modifications and 80 change orders had been accumulated. Not until these had been negotiated could the combination of NASA Headquarters, JPL, and Hughes' top-level management reach agreement on how to proceed. The revised contract was finally hand-delivered to Hughes by General Luedecke on the day the first launch occurred and was signed by Hughes officials just hours before liftoff. The signing signaled the end of a tumultuous period of planning, reprogramming, and recovering from a jumble of technical and management problems.
Another essential person in the Surveyor success story was Robert Garbarini. Bob had been serving as Chief Engineer for the Office of Space Science and Applications, and when Surveyor got into trouble, he pitched in to help in the program reviews and technical recovery planning. His almost full-time concentration on this freed me from many of the technical management  matters I had been overseeing; his strengths and experience plus his wonderful attitude in dealing with people were major factors in the turnabout of Surveyor. Bob worked closely with Ben Milwitzky, who had long provided technical strength in the program management area. The combination of Garbarini's management capability and Milwitzky's thorough technical knowledge of the spacecraft, people, and status of all the hardware and tests provided a powerful combination for working with JPL and Hughes after NASA and JPL management finally got together.
Although continuing to direct the Ranger, Lunar Orbiter, and Mariner activities' I remained involved in the Suveyor program, issuing directives for action, making assignments, and working on special problems like the one concerning the vernier engine contract. It is painfully clear now that the Surveyor program was in deep trouble in early 1964. Fortunately, "all the king's men" rallied to the cause and were successful in putting it back together again.
One of the serious incidents I now recall with a smile was related to a rash of human errors occurring in the Hughes Aircraft Company during this time. Intense management attention was directed to the problems at regular monthly meetings involving NASA Headquarters, JPL, and Hughes officials. Bob Garbarini, Ben Milwitzky, and I from NASA Headquarters and General Luedecke, Bob Parks, Gene Giberson, and Howard Haglund of JPL were usually involved. Hughes officials included Pat Hyland, Allen Puckett, John Richardson, Fred Adler, Bob Sears, and a newly named Hughes project manager, Bob Roderick. At these meetings we reviewed all aspects of the problems and assessed progress and plans so that immediate attention could be given to recovering from our series of misfortunes.
Mindful of morale and the value of incentives to encourage thoroughness and good performance, we employed the "carrot and stick" management approach The "carrot" took the form of incentive awards for meeting schedules, maintaining costs, reducing the number of man-hours involved, and so forth. As a "stick" to help reduce human error, I provided a means for Hughes management to recognize those who had caused errors or made visible mistakes. The idea came to me from my Army days when, during target practice, GIs in the pits beneath the targets used flags for signaling the results to the firing line. The most widely recognized of these was a red flag, known affectionately as "Maggie's drawers," which signified a miss of the entire target. I had a large "Maggie's drawers" flag made up, paid for it out of my Own pocket, and sent it to John Richardson, a vice president of Hughes, with  a letter suggesting that when a major incident occurred during the test or fabrication of a Surveyor the flag be flown from the company's flagpole for all to see. I also recommended that the group causing the incident be given a sign in their work area of the plant to help others recognize them as having "pulled the boo-boo" that merited the flag.
To my knowledge the flag never flew from the Hughes flagpole, but, based on the grumbling we heard and the fact that the quality of the test activities improved, I believe it served its purpose as a spur to avoiding human error. After the project was complete and everyone was relaxed again, John sent a nice tongue-in-cheek letter, thanking me for the help, and returning the flag so that I might use it on another "worthy" project. Of course, after the remarkable success of Surveyor, I would have been happy to accept it had the flag been returned with a punch in the mouth.
After so much has been said about the development and management aspects of Surveyor, it is time to recall the exciting events of the missions and the scientific findings. As initially planned, Surveyor spacecraft were to have elaborate payloads including seismometers, X-ray diffractometers and spectrometers, drills, and a soil processor that was to receive material from a soil mechanics surface sampler. Launch vehicle constraints reduced the payload to only 63.5 pounds on the first mission, and the instruments were pared down to a TV camera and some engineering measurements that made use of the landing gear structure, temperature sensors useful for other purposes, and the landing radar data interpreted for measuring reflectivity. By judiciously instrumenting the spacecraft, it was possible to deduce lunar surface mechanical properties, thermal properties, and electrical properties.
To disappointed scientists, this payload was unworthy; but compared with the pioneer who had only his eyes, Surveyor was well equipped. In addition to data obtained from engineering instrumentation, the camera produced and recorded image information about lunar topography, the nature of the surface, the general morphology and structure, the distribution of craters and debris on a fine scale, and, from observations of the footpads, an idea of the bearing strength. It also served as a photometer, giving for the first time a correct photometric function to compare with telescopic observations.
Surveyor 1 was launched from Cape Kennedy May 30, 1966, on a direct-ascent lunar trajectory. Approximately 16 hours after launch, a successful midcourse correction maneuver was executed, moving the landing point some 35 miles, to an area north of the crater Flamsteed in Oceanus Procellarum  Because telemetry indicated that one of the two omnidirectional antennas may not have fully deployed, a terminal maneuver was used that assured communications during descent. The spacecraft properly executed all commands, and the automatic closed-loop descent sequence occurred normally. Data indicated that the touchdown velocity was approximately 10 feet per second.
Of course I was in the Space Flight Operations Facility at JPL for the landing, along with other Headquarters associates and Congressman Joseph Karth. Based on experience, we had no right to expect success on the first mission, and I was prepared for the worst as telemetry reports came in. The main retro rocket had fired. The radar had locked onto the surface, and the verniers were thrusting. The spacecraft attitude was stable, and then came the altitude callouts: 1-000 feet . . . 500 . . . 50 . . . 12 . . . Touchdown. I could hardly believe it, but then, before long, the first pixels of a TV frame showed the footpad on the surface.
Within a few hours we knew a lot about the Moon. The 596-pound craft had rebounded slightly after touchdown, its footpads pushing the surface material outward slightly. The evidence was clear that the Moon's surface was strong enough to support Apollo, and the topography that had accepted a Surveyor appeared hospitable for a manned spacecraft as well. Shaking hands with Congressman Karth as we celebrated the success brought flashing memories of Mariner 1 and the Ranger failure reviews we had shared-this moment was sweeter than sweet.
The early success of Surveyor 1 was the stimulus needed to charge ahead. By the time Surveyor 3 would be launched, a sampling scoop on an extensible arm could be added to dig in the soil, test the hardness of the material, and see how it behaved in a pile. This ability to manipulate the surface the way a person might with his hand would add another dimension to exploring.
The formal name for the sampler scoop was Soil Mechanics Surface Sampler (SMSS), and its conceptual originator was Professor Ronald Scott of the California Institute of Technology. Floyd Roberson, a JPL engineer who worked with Scott, was to be the operator of the arm and its scoop, and it was his honor to command it to dig the first trench on the Moon. This was done using the TV camera to see what was being achieved a step at a time. The camera could not look directly at the surface, but at a rotating mirror. Roberson had to learn to operate the arm with every movement reversed because of the mirror; this he did by working with a laboratory model of the arm in a sandbox.
Surveyor 2 failed during midcourse maneuver when one vernier engine did not ignite; Surveyor 3 landed in Oceanus Procellarum 390 miles from Surveyor 1 with the soil sampler aboard. While Surveyor 1 had placed man's eyes on the Moon, Surveyor 3 added an arm and a hand to work the surface. Its engines did not shut off before touchdown as planned; as a result it made two "touch and go's" before coming to rest at an angle of 14° below the rim of a small crater. Examining the footprints gave much insight about the nature of the surface.
By manipulating the sampler, Roberson conducted eight bearing strength tests, pressing its flat side against the surface. He did impact tests by dropping it, and dug four trenches in the cohesive soil. However, the most exciting use of the arm was to help examine a typical "object" lying nearby.
 The object looked like a small white rock, but until now there was no way to be sure what the consistency of the object might be. After 90 minutes of manuevering inch by inch, pausing for television verification of each step, Roberson approached the object with the scoop jaw open. Careful not to miss, thereby pushing the object away, he closed the jaw, enveloping the sample and lifting it from the surface. Then came the test that could break an Earth-made brick: the jaws were commanded to exert pressure of 100 pounds per square inch on the sample. It did not break.
Hal Masursky, a scientist from the U.S. Geological Survey, was ecstatic. "If you can't crumple it like a soft clod, dig it with your fingers, or break it with a pressure or a whack, it must be a rock." In spite of this strong feeling, he cautiously described the sample as "highly consolidated material."
For Surveyor 5, the climax of the mission was the first chemical analysis of lunar material. It was done by an instrument 6 inches on a side, designed by Anthony Turkevich of the University of Chicago. Lowered to the surface by a cord, the alpha back-scatterer bombarded atoms in the soil with helium nuclei (alpha particles), knocking out protons and scattering back alpha particles and protons to a detector. By the number and energy of the particles scattered, Turkevich deduced the soil's composition. To the surprise of some scientists, the three most abundant elements were oxygen, silicon, and aluminum, in that order-the same order found in Earth's crustal materials.
Surveyor 6, carrying the same type of payload as Surveyor 5, touched down in another potential Apollo landing site, performed a confirming analysis of the soil, took 30 000 pictures, and performed the first rocket flight from the surface of the Moon when its vernier engines were reignited and allowed to "fly" the spacecraft some 8 feet to a new location. After this bold venture, we were ready for a real test. Besides, four potential Apollo sites had been found suitable, and it was time for the scientists to call the shots.
The site chosen for Surveyor 7 was in the rugged highlands among ravines, gullies, and boulders just 18 miles from the rim of the bright crater Tycho. After a look around at the "exciting" terrain, Turkevich's instrument was to be lowered to the surface, but it failed to drop. Roberson and his remote arm were brought into play, and gently lifted it to the surface. After one series of measurements, Roberson then dug a trench and moved the instrument to the freshly exposed soil at the bottom for another analysis. Finally, he lifted the instrument and placed it atop a rock. The sampler was also used to shade the instrument from the hot Sun. In addition to helping its  scientific colleague, the sampler picked up and pushed clods, hit and weighed rocks, dug other trenches, and made more bearing tests. The way the men, the camera, the arm, and the dry chemistry instrument worked as a team illustrated the power of a partnership. This last mission put the frosting on a scientific expedition to Earth's nearest neighbor and was a turning point in automated spacecraft applications.
Surveyor was a once-in-a-lifetime experience. In addition to the wonderful opportunity to land sophisticated spacecraft on the Moon, the trials and tribulations during the effort promoted the maturing of such undertakings. It might be presumptuous to say that Apollo engineers and officials were able to proceed with greater confidence because of a prior successful automated venture, but this may have been the case. I know for certain that the Surveyor experience bonded a group of us Earthlings together in a way that nothing but struggling and succeeding as a team can do.