FOR BILLIONS of years, planet Earth had been accompanied by one celestial body in its journey around the sun; in two years at the end of the 1950s nineteen new satellites with lifetimes ranging from a few months to more than a hundred years were launched.1 In evaluating the scientific accomplishments of the IGY satellite program the layman must feel a sense of bewilderment. The terms used to describe experimental goals seem esoteric, and the significance of the results and their connection with phenomena on earth are even more difficult to grasp. In many respects the layman's uncertainty is shared by scientists. The voyages of the IGY satellites were true voyages of discovery. Many of the findings were completely unexpected and often derived from experiments aimed at completely different phenomena. Areas of investigations which had hitherto commanded little attention were thrust into the forefront of scientific concern, and scientists found themselves learning a new vocabulary and confronting new problems.

If it is possible to summarize the findings of the satellite program in any intelligible way, two statements may suffice: the studies revealed the extent of the earth's influence in space, and at the same time they showed just how little we understood of the environment of the earth. Analysis of the motion of Vanguard I, for example, by establishing the fact that the earth is not spherical but rather has a bulge, disclosed unsuspected stress deep within the earth. Analysis of the drag exerted by the atmosphere on Vanguard I proved the atmosphere to be far more extensive and variable in extent than believed before. Explorer I revealed the complex region of charged particles and magnetic fields surrounding the earth. Since the end of the IGY scientists have studied the nature and extent of the Van Allen belts in detail, but physicists themselves as yet understand very little about the processes involved in the phenomena and their relationship to the more familiar atmosphere below.

If much of the nonscientific public tended to dismiss the results of the other IGY experiments as fragmentary and accordingly inconsequential, scientists attributed some importance to all data acquired in this new realm of research. In their endeavor to build up a body of knowledge about the earth's environment, they had to rely to a considerable degree on patiently piecing together scraps of information about extraterrestrial space. The IGY satellites had begun to pile up evidence about happenings beyond the ionosphere; further investigations promised to establish causal relationships among obscure phenomena. The failure of the first two attempts to measure variations in Lyman-alpha intensity during a satellite's orbit had in itself proved useful, first by the indication of strength of the radiated electrons that flooded the ionization chambers and then, after the plotting of the locations at which the saturation occurred, by showing what orbital paths a satellite must avoid when seeking data on ultraviolet radiation. Thus a third try brought success.

In appraising the satellite program, it is important to realize how much the success of its scientific phases owed to the efforts of the Vanguard team and other NRL scientists intimately associated with the project. It was they who worked out the principles and methods of thermal control, devised electronic equipment of exceptional reliability, and tested every mechanism in the packages of experiments. Whether flown in Explorers or Vanguards, the experimenters' apparatus had a dependability that stemmed in no small measure from the work lavished upon it at the Laboratory. That several experiments failed to produce the kind of data scientists hoped to obtain was never due to weaknesses in the construction of the instruments or in the telemetry, or to the integration of parts into the satellite structure. The adaptations JPL made to fit experiments designed for Vanguard into Explorers were skillful, but the basic problems were already solved before JPL engineers undertook the assignment.

What Project Vanguard, as the hardware part of the program, contributed to space exploration is widely misunderstood, doubtless partly because questions about the might-have-beens obtrude themselves. Some ask, for example, if the choice of launching system had fallen on the Army Orbiter, and if, as is highly probable, the United States had therefore been first to put up a satellite, would not the gains in American prestige have outstripped any benefits that ultimately accrued from developing a vehicle employing novel features of design and engineering and equipped with miniaturized instruments? Or, again, might not long-term progress have been faster if the National Security Council had assigned the program a top priority and the Department of Defense had then authorized production of the vehicle on a crash basis, or if DoD policy-makers had decided to risk the perils of service rivalries and made the Army responsible for the launcher, the Navy for the instrumentation, including the telemetry and tracking systems? Others, conversely, raise a very different question: wasn't the jolt to American pride in American technological superiority to all other nations a salutary blow? If the United States had beaten the Russian time-table, would not that success have perpetuated our national complacency and delayed disastrously the reexamination of our educational system and the teaching of mathematics and science in our schools? All these speculations tend to becloud judgments on Project Vanguard.

In the opinion of well-informed people, a major handicap that beset Project Vanguard from the start was its relegation to a status secondary to the ballistic missile program. The White House decree that procurement and testing of the satellite vehicle must not interfere with top-priority military projects left the Laboratory and its prime contractor more than once in an awkward position; certainly Vanguard's low priority slowed the flow of money and delayed progress on the vehicle in less obvious ways. A number of members of the Academy's IGY committees and panels and some of the Laboratory's staff named three other factors that, in their view, hampered Project Vanguard: first, the Martin Company's taking on the Titan contract and a consequent dilution of the contractor's interest in the satellite launcher; second, the appointment of a radio astronomer instead of an experienced rocket engineer as project director; and, third, the blaze of publicity in which the Vanguard teams had to operate, subjecting them constantly to Sunday morning quarterbacking and inflating their every setback to the proportions of a disaster born of ineptitude or negligence.

Time has disposed of the once frequently voiced belief that John Hagen permitted things to get out of hand, for all the men deeply involved in the project have come to see that his handling of Vanguard's many-faceted problems preserved a necessary balance between the scientific and technical aspects of the program. Whether the other two conditions cited as obstacles were indeed the source of serious trouble may be debated. Had they not obtained, one can only conjecture whether Vanguard engineers would have bettered their score of placing three satellites in orbit out of eleven tries. In any case, insofar as these factors affected Project Vanguard adversely, the damage done was chiefly to the time schedule rather than to the ultimate performance. The only valid estimate of the degree of success or failure in the undertaking must rest upon what the Naval Research Laboratory and the Martin Company did accomplish, not upon what a different regime might have achieved, or what other circumstances would have permitted under Navy aegis.

Some critics have contended that NRL's approach to design of the launching system was intrinsically faulty: in attempting to employ a first-stage rocket of marginal power, the originators of the plan had to rely on over-elaboration, compensating for minimum engine thrust by recourse to lightweight materials, miniaturization, and precision work, instead of using off-the-shelf components that otherwise would have served as well and at far less cost in time. Yet these very limitations led to many of Vanguard's most valuable contributions to the art of rocketry and miniaturization of electronic components. The engineering feat of designing, constructing, and testing within thirty months a vehicle that could and did launch an earth satellite was in itself extraordinary, especially at a time when the art of rocketry was still in adolescence. Wernher von Braun, chief architect of the Redstone, Jupiter-C, and Juno rockets, called it a miracle. Whereas the "man on the street" today is likely to look blank at mention of Project Vanguard or else identify it as "that thing that blew up," James Bridger of NRL, when asked how he ranked it, replied: "I'd call it 300 percent successful. Our job was to get one satellite into orbit during the IGY; we put up three." Ultimately more important were the technological innovations introduced in Vanguard-advances in design and in the use of materials that have influenced rocket engineering for a decade. While one school of thought has contended that Vanguard's mission did not extend to the development of models for post-IGY satellite launchers and that such work cannot properly count in any assessment of Vanguard achievements, most space engineers consider it an important entry on the asset side of the ledger.

Of the major innovations, the use of miniaturized circuits and batteries was one of the most valuable. The solar cells developed by the Signal Engineering Laboratories and so placed by Vanguard experts on the satellite shell as not to interfere with the functioning of the internal instrumentation set a new standard of efficiency and accounted for the long operating life of Vanguard I. Later satellites produced by NASA have similarly employed solar power. The use of unsymmetrical dimethylhydrazine as fuel in the second-stage rocket was another significant new departure, as indeed was much of the design of the Aerojet rocket. Impressed by the economy and utility both of the second stage and the Grand Central Rocket Company's third-stage rocket, the Air Force bought and used them in its Thor-Able booster. The fiberglass-encased third-stage motor devised by the Allegany Ballistic Laboratory and flown in Vanguard III was in turn a pioneering development; with a mass ratio of 0.91, it achieved a specific impulse of 251 seconds, a notable record for a solid-propellant rocket. Furthermore, the use of a "strapped-down" gyro platform, the rotatable exhaust jets of the first-stage turbopump which ensured efficient roll control, and the C-band radar beacon antenna employed on the Thor-Able vehicle all originated with Vanguard. Nor can a fair appraisal overlook the importance to the emerging spacecraft industry of the elaborate and original techniques the Martin Company developed to define and solve such problems as optimization of the trajectory and preflight predictions of the vehicle's performance.2

The most striking evidence of Vanguard's rich legacy to the design of later spacecraft came with the appearance of the Delta launcher, built to NASA specifications by the Douglas Aircraft Company and first flown in May 1960. The Delta second stage is the Vanguard with a few modifications-repackaged electronic components, a stainless steel instead of an aluminum thrust chamber, and a new radio guidance system. Delta's third stage is a replica of the Allegany Ballistic Laboratory's rocket used in the last Vanguard. The most versatile and reliable of all American space vehicles, Delta between 1960 and the spring of 1968 put into orbit fifty-two satellites ranging in type from weather satellites to orbiting solar observatories. "An equally important story," Milton Rosen declared, "can be told about the Stadan network, a living descendant of Minitrack, through which flows day after day, week after week, year after year, the major portion of NASA's scientific output."3

Another product of Vanguard experience was a new method of budget forecasting and cost reporting specially adapted to contracts in which research and development features made expenditures peculiarly difficult to estimate in advance and hard to keep track of in orderly fashion. This scheme to enable the project director to report on contractors' progress and financial needs was inaugurated by Tom Jenkins in the autumn of 1956. Under its provisions, the forms sent out by the comptroller to the Martin Company, and to the firms with whom the Laboratory had direct contracts, contained columns specifying the breakdown of the information required monthly. These forms quickly proved helpful to company finance officers and a boon to the government. NASA made use of the system, and, after Jenkins drafted a study explaining its workings, it was adopted by other agencies.4

Finally, the "development-testing philosophy" worked out at the Naval Research Laboratory constituted a contribution to the program that NASA recognized as basic and has acted upon consistently. The Laboratory applied it both to the vehicle and the payload. After suffering from proven charges of careless workmanship in the fabrication of the vehicle, the Martin Company in 1958 adopted the standards held up as a must by Commander Berg and, in order to proclaim the meticulous exactitude thereafter demanded of its manufacturing and inspection units, the company used as its advertising slogan: "The margin of error is zero." While static and flight testing in the field differed little in most respects from the routines observed by the Air Force and the Army, rigid calibrations of the first-stage engine during static firings and precise procedures of loading the propellant enabled Vanguard engineers to keep first-stage propellant outage at a low level without installing an automatic fuel utilization system.5 After the failure to get the TV-3 backup into orbit, the Martin and Laboratory staffs always undertook a thorough analysis of the performance of every part of every vehicle fired, whether the flight was successful or failed. In this way engineers were able to identify and correct deficiencies and thus greatly improve the reliability of each successive vehicle.

The techniques of testing the satellite's instrumentation were still more exacting. Assembling equipment that would simulate the conditions to be encountered in the vacuum of space and developing processes that would reveal the nature of weaknesses in experimenters' apparatus required scientific knowledge and expert craftsmanship. From the shake table used in measuring vibration resistance to the vacuum tank and the gauges employed in registering temperature changes in the satellite placed within it, every test device was carefully constructed and operated. Testimony to the quality and thoroughness of the procedures lay in the fact that all the instrumentation flown in IGY satellites functioned properly.

All in all, the record is clear. Project Vanguard justified the faith of its supporters not only by putting instrumented satellites into orbit during the IGY but by developing a vehicle with "growth potential," and in the process, by advancing the art at a cost in money that, in 1961, looked incredibly small to experts. The one black mark against it is that it did not "get there fastest." Homer Newell's summary judgment ran: "A failure? Vanguard was a resounding success!"6

The oblivion to which most Americans consigned Project Vanguard at the end of the l950s no longer distresses the men who gave three years of their lives and ate their hearts out in the endeavor to make Vanguard a landmark on the unending road to new scientific knowledge. They know that it was and is a landmark. Scientists at the National Academy and experienced leaders at NASA acknowledge it as a progenitor of all American space exploration today. "The overall scientific program developed for use with the Vanguard launching system," stated the satellite panel toward the end of its life, "has made possible the total program of space vehicle instrumentation, observation, and data reduction carried out under IGY auspices. Additionally, it has provided the original basis of the present expanding program of scientific experiments for space research for the United States."7 True, it did not produce the first artificial satellite to circle the earth; true also, the initially rejected launching system nurtured by the Army Ballistic Missile Agency and refined by JPL put up the apparatus that netted the most valuable data collected during the IGY. But those facts have become largely details of history. Recognition of the Explorer achievement should not denigrate Vanguard's, just as Vanguard's cannot detract from Explorer's. To the pure scientist all that matters is that a new research tool became available and its proven utility has ensured its continuing use. To thousands of imaginative Americans of the l960s, the expansion of knowledge of interplanetary and solar space represents a creative undertaking in its own realm as inspiring as the work of the cathedral builders of the Middle Ages.