Chapter 7

ONBOARD EXPERIMENTS

AND INSTRUMENTATION

THE FIRST plan for an onboard satellite experiment to reach the chairman of the USNC was "A Proposal for Cosmic Ray Observations in Earth Satellites" submitted by James Van Allen, George Ludwig, and several colleagues at the State University of Iowa. It bore the date 28 September 1955, several days before the National Committee appointed the technical panel. Eager to start on the scientific work that constituted the reason for setting up a satellite program, the Iowa group had not waited for information on the configuration of the Vanguard satellite or the weight of instrumentation it could accommodate, or whether it could be launched into either a polar or an equatorial orbit. Van Allen's covering letter set forth his belief "that the needs and desires of those contemplating use of the vehicles for scientific work [should] be adequately taken into account in connection with all major technical decisions." He took for granted that "a technical committee of broad interest and competence" would decide on "the assignment of payload space" in each satellite. As he assumed also that the program would be a continuing one in which there will be many satellites flown over an indefinitely extended period of time," he envisaged development of a succession of vehicles, capable of placing in orbit increasingly capacious satellites from two feet to three feet and over in diameter and weighing from five pounds to fifty and more.1

It is not surprising that Van Allen had an experiment planned so promptly, for he had had long talks with Ernst Stuhlinger, chief scientist at the Army Ballistic Missile unit, when both men were at Princeton in 1953-1954. Stuhlinger's technical knowledge and vision had inspired the younger man to prepare for the day when satellites would carry scientific instruments beyond the earth's atmosphere. What he learned from Stuhlinger about the work afoot at Huntsville, furthermore, led him to believe in 1955 that a sizable payload would be possible in an IGY satellite, even though he realized that the Vanguard first stage would have far less power than the Redstone rocket. In fact, as he acknowledged long afterward, from the beginning he designed the pot of instruments for the cosmic ray observations in a form that would readily adapt it to installation in the satellite of the bigger vehicle were that eventually to be available.2

"Cosmic ray observations above 50 kilometers altitude," Van Allen stated in the original proposal, "have a special simplicity and importance because only above such altitudes can one's apparatus be placed in direct contact with the primary radiation before its profound moderation in the earth's atmosphere." Over the preceding nine years he and his associates had pursued investigations by means of sounding rockets, but an instrumented earth satellite could provide in a week more satisfactory data than scientists could obtain from rockets in twelve years of work. A worldwide survey from a satellite would furnish information on the geographical distribution of arriving cosmic radiation and permit deductions about the magnitude and nature of what is solar in origin. If the satellite orbit were pole to pole, or even equatorial, the survey would produce a mapping of the earth's effective geomagnetic field and reveal the correlation of fluctuations in cosmic ray intensity with terrestrial magnetic and solar activity. Cereokov detectors, already successfully used in Skyhook balloon flights, could measure the relative abundance of the light elements of cosmic radiation-hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen and fluorine and thus establish the distribution of nuclear species in the primary radiation before it encounters the atmosphere. Simple measurements would also increase knowledge of the nature of the cosmic ray albedo of the atmosphere. (Albedo is the ratio of the amount of electromagnetic radiation reflected by a body to the amount incident upon it.) As the albedo consists of products of nuclear reactions, in the upper levels of the atmosphere. which happen to proceed in upward directions, measurement of the total cosmic ray intensity as a function of distance from the earth should permit determination of the magnitude of the albedo. A simple detector in the satellite should, moreover, furnish means of charting the arrival of auroral radiations at the top of the earth's atmosphere.

The necessary instrumentation, consisting of a Geiger counter, Cerenkov detectors, and telemetry equipment using conventional batteries would not weigh more than fifty pounds. or, if solar batteries were available, not more than thirty pounds. If the telemetering of data were to be continuous to ground stations, the usual methods of data transmission would he used; if communication were to be intermittent, a coded integrated system would be employed. Preparatory work at the university laboratory could begin at once, and the flight apparatus could be completed in about a year, provided the government-supplied telemetry system were ready by then. The experimenters wanted to share in choosing the characteristics of the system and in its preliminary testing. They planned to construct twenty sets of apparatus, fifteen to expend in preliminary tests, five to be flown in satellites. Van Allen, whom a government financial expert once characterized as "a small-town boy, a backyard scientist" who believed in keeping things simple, estimated the cost for approximately three years' work at $66,125, including $1,000 for the time spent on reduction of the scientific data and publication of the findings. That estimated cost would rise six months later to $106,375.3

A second proposal came a few weeks later, when Fred Singer of the University of Maryland outlined a plan for "Measurement of Meteoric Dust Erosion of the Satellite Skin." Singer's idea was to design a radioactive gauge to place on the satellite's shell in order to measure the flux of integrated cosmic dust and compare the results with those obtained by optical observation from the earth. The method should gauge the effects of erosion on different surfaces of the satellite and reveal the changes of surface and aerodynamic properties as well as the subsidiary effects on satellite albedo and temperature. He proposed to measure erosion by observing the decrease in the activity of a radioactive portion of the satellite skin. A beta ray detector could monitor the activity on the interior surface of the shell by incorporating in the skin such beta emitters as phosphorous 32, strontium 89, and others. The investigator could analyze the resulting data in comparison with those obtained in the laboratory from charging dust particles, accelerating them electromagnetically, and then examining the surface under a microscope. The experiment would take about two and a half years to complete and would cost about $52,900.4

Because of Hagen's reluctant agreement to discard plans for a conical satellite and employ a sphere instead, it was late November before Homer Newell could present to the TPESP a summary of what the major characteristics of the Vanguard satellite were to be. Since the entire satellite was to weigh in the neighborhood of ten kilograms, Newell explained, only about one kilogram could be devoted to the scientific payload exclusive of the telemetry and batteries. That news was obviously disconcerting to Van Allen, The satellite system was to include two concentric spheres, an outer sphere twenty to thirty inches in diameter, and a smaller central sphere, about a foot in diameter, which would house much of the research instrumentation, Each sphere would be pressurized independently with helium. Welded seals were to be used throughout, "The various equipment will, however, be designed so as to operate even though the outer sphere loses its pressure." Just as tracking considerations dictated the configuration of the shell, so the Laboratory designers believed a spherical inner container would simplify temperature control.5

"Temperatures between 5° and 50°C will be acceptable to all of the items operating in the satellite." Transistor characteristics were the principal limiting factor. "More advanced transistors probably will be able to operate successfully in the range from -20° to +80°C. It is expected that this temperature range can be maintained within the central sphere provided the surface sphere is coated with an appropriate material such as ALSAC. This material is highly reflective to solar radiation, yet highly emissive with respect to infra-red radiation."

"Spin rates between 250 and 400 r.p.m. will probably occur in the Project Vanguard satellites." Expectations ran that all equipment could be so designed as to withstand the accelerations to which the vehicle would subject it. The telemetering system was to be tied in with the Minitrack system. Estimates put the telemetering reception interval during each revolution at a minimum of eight seconds at a 200-mile perigee, but an increase to as much as a minute might be possible.6

Every scientist preparing an experiment would have to take these conditions into account. Transistorized circuitry, desirable because of its light weight, had the disadvantage of sensitivity to extremes of temperature. Similarly the capacity of the satellite's outer shell to resist puncture by meteoric and micrometeoric particles and to withstand the action of atmospheric ions would affect the level of pressures on the inner sphere and might thus modify performance of the instruments housed in a central insular region. To accumulate exact data on surface and internal temperatures, surface erosion, and internal pressures. NRL proposed to conduct environmental studies in the first satellites launched.

Hermann LaGow and several NRL associates were designing instrumentation for these studies. A pair of thermistors mounted on the satellite's outer surface and one thermistor on the "instrumentation island" thermally insulated from the skin would measure the temperatures. Surface temperatures would probably vary widely as the satellite passed successively through daytime and night conditions, but changes would probably be relatively small on the instrument package itself. To gauge pressures inside the outer sphere NRL planned to install snap switches which would relay signals when the internal pressures dropped below predetermined levels; a final signal would start the operation of a Pirani gauge to measure leakage rates. The experts believed it possible to distinguish between leakage caused by meteoric punctures and that caused by imperfections in welding and sealing of the outer sphere. A coating, with suitable electrical resistance characteristics, on a portion of the satellite's outer skin was to form a circuit element capable of transmitting data on the rates of surface erosion; as erosion decreased surface thickness, resistance would increase. About five seconds would be enough telemetry time to transmit the data to ground stations. The instrumentation would weigh about one hundred grams, the miniaturized batteries about two hundred.7

At the same time Newell described two physical experiments that NRL considered well adapted to installation in an early Vanguard. Either of these could be flown along with the equipment for the environmental studies and use the same batteries. Leslie H. Meredith had prepared one of these proposals, namely, an investigation of the rigidity spectrum of primary cosmic rays, but he withdrew it some months later because it appeared unlikely to net enough information to be worth pursuing. The other, more promising, scheme came from Herbert Friedman and associates in the Electron Optics Branch of the Laboratory's Optics Division. They sought to determine the variation in the intensity of solar Lyman-alpha radiation during each revolution of the satellite about the earth. Lyman-alpha radiation is the emission from the strongest line within the ultraviolet region of the hydrogen atom's spectrum. Light of this short wavelength is not transmitted by the earth's atmosphere, but delicate instruments in a satellite might record the increases in the radiational intensity to be expected during the minutes of a satellite's flight through sunlight in comparison with the level of radiation registered during darkness. The experimenters planned to use an ion chamber sensitive only to the narrow region of the spectrum centered on the Lyman-alpha line, and circuitry to store the peak signal developed by the detector. Photo-ionization of the nitric oxide filling the ion chamber would create the spectral sensitivity. A photocell would relay data on the satellite's aspect relative to the sun. Five seconds would probably suffice to read out all information by telemetry. The instrumentation, capable of operating continuously for approximately five hundred hours, would weigh about six hundred grams and occupy about five hundred cubic centimeters of space in the instrument package.8

Thus at the end of 1955, a month before the creation of the Working Group on Internal Instrumentation, the TPESP had on hand five possible experiments to consider. As anticipated, the symposium held in Ann Arbor late in January 1956 brought in an additional crop of proposal-indeed, a number of sufficient interest to the scientific world to warrant publication in book form.9 But by no means all the presentations described specific experiments: some dealt with problems awaiting solution but offered no explicit plan for using instrumented satellites to answer the questions; a few papers were directed at engineering or tracking techniques; one or two called for the use of apparatus which admittedly was unlikely to be perfected during the IGY. Nevertheless, by March, when the panel's Working Group on Internal Instrumentation held its first meeting, the WGII, so-called, had before it eleven propositions that merited serious consideration and another four that needed clarification.10

Of the men whom Van Allen chose to serve with him, Porter, Odishaw, and Lyman Spitzer, as members of the parent panel, and Herbert Friedman of NRL were already familiar with the satellite program; William W. Kellogg of the RAND Corporation, Leroy R. Alldredge of the Operations Research Office of the Johns Hopkins University, and Michael Ference, Jr., of the Ford Motor Company alone needed briefing. Van Allen began by summarizing the outcome of a conference he and Porter had attended in late February at NRL to discuss plans with Hagen, Rosen, and Newell, The conferees had agreed that the objectives of the program were, first, to place an object in orbit and prove by observation that it was there; second, to obtain a precision optical track for geodetic and high-altitude atmospheric drag measurements; and, third, to perform experiments with internal instrumentation. After achieving the second objective in one or two flights, the third goal would take precedence over the second. Rosen had emphasized the necessity of keeping satellite weight to a minimum until such time as the vehicle proved able to carry more. "If necessary to buy improved performance by reduction of payload," the best way, the five men thought, would probably be to start flights with an empty third-stage bottle 18 inches in diameter by 50 inches in length, try next a 6-pound payload consisting solely of the Minitrack instrumentation in a minimum size capsule, next an 8.5- pound payload in a 20-inch sphere, and thereafter payloads ranging from 14 to 18.5 pounds with 2 to 5.5 pounds allowed for scientific instrumentation. Larger loads might be feasible later. The Laboratory would supply experimenters with "black-box" specifications for payload capsules, and a list of pertinent Minitrack characteristics. The salient features of the telemetry system were not yet determined.11

These terms left open the possibility of using a cylindrical package of instruments, if not the cylindrical or conical outer body which Van Allen and Hagen had wanted, but the chances looked slight of getting as much as eight pounds of instrumentation into any IGY satellite. Van Allen and George Ludwig, in an attempt to meet the Vanguard specifications, had already scaled down their plan for cosmic ray observations, but the severe restrictions on weight automatically knocked out several otherwise useful proposals submitted at the Ann Arbor symposium.12

With these conditions in mind the working group turned to establishing the criteria that should govern the selection of onboard experiments. First was that of scientific importance. "to be measured by the extent to which the proposed observations, if successful, would contribute to the clarification and understanding of large bodies of phenomena … and/or be likely to lead to the discovery of new phenomena"; the second was that of technical feasibility as established by use of similar techniques in rockets or other scientific vehicles, by the "adaptability of the instrumentation to the physical conditions and data transmission potentialities of presently planned satellites," by "the nature of data to be expected," and by "feasibility of interpretation of observations into fundamental data"; the third was that of the competence of the persons or agencies making proposals, an assessment based on past achievements in work of the kind proposed; and the fourth was that of the necessity, or strong desirability, of using as the vehicle for the experiment a satellite rather than a sounding rocket or a balloon, The group, however, went on record as wanting to encourage proposals that would help develop a "reservoir" of scientific competence in devising experiments for future satellite flights "even though such work may not yield practical apparatus for the short-range ICY program.13 Is The WGII, in short, saw its task as extending to plans for space exploration long after the ICY ended.

With long-term objectives in view, the working group also decided "to give further consideration to the establishment of a worldwide net of telemetering receiving stations for the continuous or nearly continuous reception of observed data" and "to consider concerted action on development of solar batteries, telemetering systems of more general applicability, data storage and read-out devices." The main business of the session, however, was the preparation of a preliminary listing of priorities among the experiments already submitted, despite the virtual certainty that the months ahead would bring in a number of new propositions, some of which might fill existing gaps in the fields of inquiry thus far covered. The consensus ran that the selection of internal instrumentation was lagging behind other parts of the satellite program; since the apparatus for every experiment chosen would have to undergo rigorous laboratory tests and, if possible, flight tests in rockets in order to check its capacity to withstand the vibration, the shock of accelerating velocity, and the environmental conditions to be encountered in the vacuum of Space, the least complicated instruments might well take at least two years to perfect. There was no time to lose. So the WGII then and there ranked the proposals before it, putting in order of choice the experiments that appeared to have most scientific value and be best suited to early satellite flights, and, in a second, "B," category those that might be flown later but were as yet of doubtful utility or feasibility.14

After abbraising the WGII's report, the panel voted to limit for the time being "the positive standing on the Priority Listing" to nine projects, thereby discarding three. The subsequent voluntary withdrawal of two others further reduced the number. By common agreement, Friedman's Lyman-alpha experiment, the environmental studies, and the proposal from the State University of Iowa headed the list from the beginning, even though sounding rocket experts at NRL had pointed out that a series of rocket probes could provide cosmic-ray observations as well as could an instrumented satellite.15 The plan of Van Allen and Ludwig by now called for apparatus that was to consist of two parts: instruments for continuous transmission of signals marking the instantaneous intensity of cosmic rays registered by the Geiger-counter, and, second, equipment to store the instantaneous intensity data during each orbit for read-out on command over the Minitrack stations. A small cylinder would house batteries, a receiver, a transmitter, tuning forks, a tape recorder driven by a ratchet system, scalers, and generators. The Geiger-Mueller tube would project about 4.5 inches from the top plate of the cylinder.

Fourth on the priority list was an experiment entitled "Measurement of Interplanetary Matter," submitted by Maurice Dubin, E. R. Manring, and others of the Geophysics Research Directorate at the Air Force Cambridge Research Center. Their plan was to detect the spatial distribution and size of particles colliding with the satellite-even those as small as one micron in diameter-by recording the acoustical energy generated on impact. Instrumentation would consist of a sensitive piezoelectric transducer on the inside surface of the satellite shell, a transistorized amplifier, a storage device, a power package, and a time-delay switch set to operate after the Minitrack telemetry began to transmit. The memory device was to count the number of stored impacts, record the distribution of particles by size, and transmit the information when the amplifier was in use. Somewhat similar in purpose to Singer's rather simple meteoric dust erosion experiment, Dubin's appeared to have greater scientific utility; perhaps the two might be combined. The panel recommended that Dubin receive the grant of $89,045 that he requested, Singer, though his plan stood in category B, a grant of $47,150.

At the top of the B list was a proposal for meteorological observations, prepared by William G. Stroud of the Signal Corps Engineering Laboratories (SCEL). Its primary objective was to measure the global distribution and movement of cloud cover and to relate it to the gross meteorology of the earth. Contrasts in terms of sunlight reflected from cloud, sea, and land masses, as viewed from a spinning satellite during the telemetry time, should furnish the basic data. Two photocells using a single telemetry channel would look out in diametrically opposite directions at a known angle to the spin axis of the satellite. The signals from the photosensitive cells would be stored in an airborne magnetic tape recorder and, at interrogation, be played back during a one-minute interval over a one-watt transmitter. A switch would turn off the equipment during periods of darkness and turn it on again when the satellite reemerged into sunlight. Although the question would later arise as to whether the data could be transmitted in form that lent itself to meaningful scientific interpretation, the panel recommended a grant of $93,000 to develop the apparatus.16

An experiment of great scientific interest but of somewhat doubtful technical feasibility was H. E. Hinteregger's proposal to develop photoelectric techniques for study of extreme ultraviolet solar radiation. A member of the Geophysics Research Directorate of the Air Force Cambridge Research Center, Hinteregger hoped to trace the high yields of photoelectric emission in this range of radiation. Although the probability of adapting the equipment to an IGY satellite looked small, the WGII and the panel believed the plan worth encouraging. An award of the $5,000 Hinteregger requested would keep the total figure recommended for grants to date to $371,320. The panel therefore could allot $275,000 for NRL experiments and keep $570,000 for pending projects without exhausting the $1,262,000 earmarked in the satellite budget for internal instrumentation.17

During spring 1956 several men tendered proposals for ionospheric studies, but all of them called for use of ground station receivers and airborne transmitters with radio frequencies incompatible with the Minitrack's 108 megacycles. While suggesting that the authors discuss possible compromises with John Mengel, the WGII undertook to remind all experimenters that their equipment must not interfere with Minitrack and should rely on the Vanguard telemetry system. Telemetry time during an initial orbit would be only thirty seconds, although after the orbit was determined, the time could be increased to two or three minutes by changing the positioning of the ground station antennas. A Vanguard development still in the tentative stage might provide a sixteen-channel memory circuit for storage of data during orbit and a read-out system responsive to command from telemetry at the ground stations. Magnetic tape running at a constant speed would record the signals at ground stations and playback tape would give the data on wide film or paper strips with time markers.18 Experimenters who received grants, the panel decreed, must be informed promptly of their chances of having their apparatus flown during the IGY. The working group had decided to assign each high priority project to a particular vehicle; if a bird failed to orbit, the next vehicle launched would carry the experiment, but, if a second failure occurred, the untried experiment would have to yield to the next on the list. A prototype of the apparatus for every project in the A category should be ready by January 1957 for WGII approval.19

Of the three propositions the WGII added before the end of 1956 to those tentatively chosen earlier, one was an experiment called "Geomagnetic Measurements" prepared by James Heppner and colleagues at NRL. In essence it was the magnetometer experiment outlined in NRL's original presentation to the Stewart Committee, later described in a paper at the Ann Arbor symposium, and now reworked to accommodate it to the small payload of a Vanguard satellite. Its objectives were, first, to gauge the intensity of the earth's main magnetic field during magnetic storms and measure its contribution to the total storm disturbance as a function of time and latitude; and, secondarily, "to determine the existence or nonexistence of extraterrestrial currents during the initial phase of a magnetic storm and to improve our knowledge of ionosphere currents giving rise to diurnal and irregular variations of the magnetic fields, especially near the magnetic equator." The principal instrument was to be a nuclear magnetic-resonance magnetometer in the form of a coil around a sample of liquid that contained a high proportion of protons. A magnetic field would be produced by passing a current through the coil, thus polarizing the protons' magnetic moment. Upon cutoff of the polarizing current, the proton moments would precess about the earth's field at a frequency determined by the field's strength and induce a voltage at that frequency in the coil. This signal, following amplification, would be fed to the telemetering transmitter for transmission on command to the Minitrack stations. At each Minitrack station there was to be "a proton precessional magnetometer to simultaneously measure accurately the total scalar field, declination and inclination," The paucity of observation time and the lack of a recording and storage device in the satellite led the working group to question the value of the attainable results, but Van Allen, after displaying a model of a magnetometer built and used successfully in rocket flights by the State University of Iowa, testified to the probable workability of the special model under design by Varian Associates of California. With this experiment approved for funding, the sum allowed for NRL's three onboard projects rose to $597,000.20

The second new experiment the WGII recommended-rather hesitantly, to be sure-was a plan largely worked out by William O'Sullivan of the staff of the National Advisory Committee for Aeronautics (NACA) at Langley Field, Virginia. It required no scientific instruments and little equipment other than a gas-filled bottle and a device to eject a thirty-inch inflatable sphere from the satellite at the moment of third-stage burnout. It was designed to permit optical observers to compute air densities and to measure atmospheric drag on the aluminum-foil-covered plastic body. If the perigee of the satellite were less than 200 miles, the life of the sphere would be extremely short, but as the weight of sphere, gas tank, valve, and ejection trigger together would not exceed nine ounces, the paraphernalia could go Into a satellite carrying fairly heavy instrumentation for another experiment. NACA would meet most of the costs.21

Verner E. Suomi of the University of Wisconsin proposed the third experiment recommended at the end of 1956. The objective of Suomi's experiment, known as "Radiation Balance of the Earth," was to measure the long-wave radiation emitted from the earth, from direct sunlight, and from sunlight reflected from the earth, and also the short-wave radiation reflected from the earth and either shielded from or insensitive to the other radiations. Harry Wexler of the Weather Bureau, who had submitted a somewhat similar but more complicated plan, warmly supported Suomi's proposal as scientifically important and technically feasible. It should supply means of charting the gains and losses in the earth's heat budget during a satellite's lifetime. Of four small thermistor sensors mounted on the ends of the satellite antennas, one sensor would be sensitive only to long-wave radiation emitted by the earth, the second equally sensitive to other types of radiation, and the third and fourth sensors only to short-wave radiation reflected from the earth. During the satellite's orbit a selector switch would monitor each sensor and feed signals from a coding oscillator to each for a preselected time. An airborne magnetic tape recorder would store the data until, upon passage of the bird over a Minitrack ground station, a command turn-on signal initiated the playback sequence. While the intricacy of the instrumentation militated against the chances of its being ready for use during the IGY, the panel recommended an initial grant of $50,000.22

Although priorities necessarily would change if tests of instrumentation so dictated, in February 1957 the panel made its selection of experiments to fly in the first full-size Vanguard satellites. Assuming four successful shots during the IGY, the WGII had proposed to assign a "package" containing two experiments to each of the first three birds, a single experiment to the fourth. The panel concurred. Package I was to take the equipment for the environmental studies and the Lyman-alpha experiment. Package II was to contain the apparatus for Van Allen's cosmic ray observations and either for Dubin's measurements of interplanetary matter or for Singer's, of meteoric dust erosion, provided either of those could employ a masked photocell instead of the radioactive method. By April progress on Dubin's instrumentation captured for it the coveted place in package II. Package III was to carry the instruments for Heppner's geomagnetic measurements and O'Sullivan's inflatable sphere. For package IV the panel wavered between Stroud's cloud-cover experiment and Suomi's radiation balance. The upshot was a decision to let both proceed until the work was further advanced and then request the country's leading meteorologists to name the more useful of the two.23

Although the expense of developing internal instrumentation was beginning to run unexpectedly high, the panel assigned "back-up" status to several projects. So Hinteregger's scheme of measuring extreme ultraviolet solar radiation won official endorsement and, later flown in a rocket, produced some significant data. Singer got funds to complete his radioactive meteor erosion gauge, money which the panel switched in 1958 to support his endeavor to devise means of determining the electrostatic charge accumulated by a satellite, but he never submitted detailed designs or an experimental prototype. A grant went also to the group of men, headed by William Pickering, at the Jet Propulsion Laboratory for development of instrumentation to measure the integrated light from various parts of the celestial sphere, using a set of color filters and a photomultiplier detector. Planned for use in case more experiments could be flown during the IGY than anticipated, the JPL equipment was never put to the test in a satellite, but the work on it proved useful in preparing later projects. An experiment proposed by Martin Pomerantz of the Bartol Research Foundation and Gerhardt Groetzinger of the Research Institute of Advanced Studies was in turn given funds, even though the ion chamber and circuitry designed to identify the heavy primary cosmic ray nucleii and the possible variations in their flux appeared unlikely to be available for IGY satellites.

Interestingly enough, no experiment in the life sciences received endorsement. Yet in 1951 and 1952 Kaplan had viewed the possibilities of medical research in the aeropause as an impelling reason for a satellite program and the NRL proposal to the Stewart Committee had alluded to the feasibility and utility of studying the behavior of living cells in the vacuum of space. Early in 1957, a biologist at the National Institutes of Health submitted a plan for recording the effects on yeast cells placed in an orbiting satellite, but the panel postponed action on the idea.

All told, the panel rejected seventeen proposals and, counting those dealing with tracking and engineering problems, approved over twenty before October 1957.24

In backing experiments too heavy or too elaborate for Vanguard satellites or adapted primarily to space probes in rockets, the TPESP was adhering to the principle announced by the IGY National Committee at the end of 1956. If, as the committee and the panel assumed, the scientific exploration of apace continued after the IGY was over, technological advances would surely supply the bigger vehicles needed for the purpose. Indeed as early as May 1957 the panel had reason to think the time near when larger satellites than the twenty-inch Vanguard sphere could be circling the earth, for Pickering reported that the Army already had available a launcher capable of putting a thirty-pound payload-which would include the rocket casing -into an orbit of 1,000-mile apogee and 200-mile perigee. Pickering knew whereof he spoke, inasmuch as the Jet Propulsion Laboratory under an Army contract had been working closely with the Army Ballistic Missile Agency on developing the Jupiter-C rocket. Despite Vanguard's configuration and the relatively slow spin rate of its last stage, at least one package of satellite instrumentation, notably that for the Van Allen experiment, could be fairly easily adapted to flight in the Army vehicle. When Porter asked why the Defense Department did not sanction use of the new rocket as a backup for the NRL-Martin launcher, Paul Smith explained that the DoD had considered the plan but vetoed it as needless; Vanguard tests were on schedule and satisfactory.25

Work on the satellite structures and instrumentation meanwhile had moved along rapidly at NRL. Since every experimenter was to furnish his own apparatus, the naive reader might assume that the team at the Laboratory would have relatively little to do: merely supply the satellite shell, the telemetry, the antennas, and the tracking transmitter, and then install the package of experiments. But those tasks in themselves were formidable. The satellite as planned had to carry a device for separating the sphere from the rocket casing after third-stage burnout; the shell and every mechanism in it must be sturdy and lightweight; and to fit all the items into a twenty-inch sphere required miniaturization of an order never before thought attainable. The layout of instrumentation, furthermore, had to vary from one satellite to the next so as to adapt each to the particular experiments it was to accommodate. Nor did the job end there, Thermal control presented enormous difficulties, and the entire testing program demanded scientific knowledge, great ingenuity, and endless patience.

Common background simplified the dealings of the Vanguard scientific unit with the authors of the IGY experiments, for, like most of the latter, a number of men at the Laboratory, as pioneers in space exploration with sounding rockets, had had to design and build their own instruments in the past. Mutual respect and cordial relations between the two groups could not, however, greatly lessen the steadily mounting burden of work carried on for Vanguard by NRL scientists. Homer Newell and his deputy, John Townsend, who were in overall charge and directed the program through a so-named Satellite Steering Committee, accordingly asked Robert W. Stroup early in 1957 to serve as general coordinator and trouble-shooter. In late April 1957 the steering committee, with Hagen's approval, arranged a three-day conference which brought all the experimenters to the Laboratory where they could see the work in progress, observe the testing arrangements, and discuss their individual needs and quandaries.26

There Robert C. Baumann, head of the mechanics and structural unit, described the separation device under manufacture by the Raymond Engineering Laboratory of Middletown, Connecticut, He also displayed models of the twenty-inch satellite shell that Brooks and Perkins of Detroit were spinning from flat sheets of magnesium into two hemispheres which skilled craftsmen at NRL then riveted together; a small trap door gave access to the interior. The mechanical features of the folding antennas to be affixed to the outer surface were largely of Baumann's design; the electronic parts were the work of Martin J. Votaw and Roger Easton; NRL shop hands were building the arrays: Mechanics in the shop were also fabricating the 6.4-inch "grapefruit" to be flown in the test vehicles. For the satellites carrying packages I, II, and IV, the original scheme of an inner sphere to house the scientific instrumentation had given way to a cylindrical container attached to the outer shell by a spider framework of tubular metal; teflon-covered supports shielded the pot from the grids. The satellite carrying the magnetometer experiments, on the other hand, was to have a different configuration: a thirteen-inch fiberglass sphere with a fiberglass stem projecting from it several inches to support the sensor. At a later date the steering committee would discover the necessity of providing a spin-reduction mechanism for the satellites flying the cloud-cover experiment and the NACA inflatable sphere in order to allow, in one case, a longer scanning interval for the photocells and, in the second case, ample time to inflate the plastic subsatellite.27

Whitney Matthews, who was in charge of the electronic layout within the spheres, demonstrated the general scheme of stacking the layer of "cards" of miniature mechanisms and locating their power supply. As was true of other features of the satellites, each package would differ somewhat in both content and arrangement from every other. Although little of the work was in final form in April 1957, the economy of the intricate layouts, the complexity of the tiny parts, and the delicacy of the workmanship were already plainly visible. Roger Easton then explained in detail how the tracking and telemetry equipment would function. The tracking signals would be amplitude modulated for telemetering the scientific data obtained from the satellite-borne detectors, A transistorized transmitter in the satellite weighed 1.25 pounds, including the weight of Minitrack batteries for two weeks' operation, and used about 7.5 pounds of mercury cell batteries that would give three weeks of continuous operation at fifty milliwatts output for telemetry. Telemetering might be continuous or could function on command. When commanded, a receiver weighing twelve ounces including its power supply would pick up the signals sent from the ground. While the command receiver in every satellite would be standard, the telemetry transmitter might differ in type, depending on the requirements of the experiments carried. On the ground the telemetry receiver was to be located at some distance from the tracking receiver. NRL had built the first tracking transmitters in its shop; testing and evaluation of performance had been going on at the Blossom Point station since July 1956.

Of equal or perhaps even greater interest to the visiting scientists attending the conference were the accounts of the methods under development to provide thermal protection for the satellite shell and its payload. Solving these problems, above all those deriving from the effects of radiation under various conditions, called for pooling the talents and experience of several men, notably Hermann LaGow, who had planned the environmental studies accepted for the first satellite flight, Richard Tousey and Louis Drummeter of the NRL Optics Division, Milton Schach of the Electronics Division, and George Hass of the Engineer Research and Development Laboratories at Fort Belvoir.

Tousey had made some of the first calculations in the fall of 1955, contributing his knowledge of optics to ensure that protective coatings on the exterior of the booster and on the satellite shell would have sufficient reflectivity to permit telescopic observation of the course of the rocket as it rose and then optical acquisition and tracking of the satellite in space.28 Schach undertook the "thermal design," that is, the calculations of what temperatures to expect at various points in the satellite's orbit, in darkness and in daylight, the selection of the optimum thickness of coating materials to emphasize their emissiveness of solar heat radiation, and methods of keeping the satellite's surface free of contaminating substances such as soot which would ultimately raise the satellite's temperature. Hass worked out the techniques of applying the successive surface coatings-the gold plating, the chromium evaporated to vapor and deposited to serve as a primer, the silicon oxide to serve as a barrier, the thin layer of evaporated aluminum to give a mirror-like finish, and finally a film of silicon oxide to control emitted radiation. Drummeter and Schach were chiefly responsible for developing the sunlight simulator with carbon arcs as the source of high- intensity light. Through windows in the large cylindrical vacuum tank in which the coated sphere sat for two or three days of testing, the simulated sunlight beat upon the satellite's surface and indirectly heated the inner pot of instruments. Measurements of the effects furnished means of determining the most desirable material and thickness of the layering required. LaGow acted as advisor and monitor on all these operations. Every man concerned with temperature control worked closely with every other.29

Newell and Townsend, who had initially objected to launching a 6.4- inch satellite with no internal instrumentation, were reconciled to the plan as thermal testing proceeded, for the agreement to place temperature sensors on the 6.4-inch shell promised to verify the findings of the Laboratory tests or else supply data that would permit development of better thermal control for the larger instrumented satellites. Although the research and testing was still going on when the conference with IGY experimenters took place in the spring of 1957, the NRL thermal experts were already fairly confident that they could limit temperature changes within the instrument container to some two or three degrees during any one orbit. While expectations ran that a Vanguard satellite would have only a few weeks' life, the possibility of its lasting longer led to endeavors to adapt thermal controls to seasonal as well as diurnal changes.

The men attending the conference received, moreover, thorough indoctrination in the standards of performance which the Vanguard group demanded of every experimenter's equipment. If, when put through the whole gamut of tests at NRL, his instruments could not withstand extremely high random and sinusoidal vibrations, changes of temperature ranging from 0° to 60° C, and a simulation of the sudden acceleration that would occur when the second-stage rocket separated from the first or the second from the third, then the Satellite Steering Committee could reject the experiment outright, unless the originator was able to correct the weaknesses thus revealed. He was to test his work carefully in his own laboratory before sending his instrumentation on to NRL. If possible it should also be tried out in a rocket flight. After testing each item, the Vanguard group would need a minimum of three months to check the reliability of the assembled package. The precious space in a satellite must not be wasted on faulty scientific paraphernalia. All electronic and experimental equipment should have a life of at least 1,000 hours.30


J. Paul Walsh and Homer Newell

J. Paul Walsh (left), Deputy Project Director of Vanguard,
and Homer Newell participate in a conference in the director's office.


At Van Allen's request, a special session explored the progress of the development of dependable solar batteries, especially the work going on at the Signal Corps Engineering Laboratory. Using chemical batteries, Vanguard satellites and most of the onboard apparatus thus far proposed would have an active life of only a few weeks. Satellites with longer life consequently needed a solar battery system for long-term power. All experiments would have far greater value if they could operate for several months. Although the SCEL during the past year had solved a number of problems, others remained, notably the sharp decline of open circuit voltage when temperatures rose from 20° to 80° C. A new type of cell, however, might provide an answer. Use of clusters of solar batteries, moreover, might charge a low- voltage secondary battery, while transistor d.c.-d.c. converters could supply the higher voltages, such as the twenty-three volts needed for the Minitrack transmitter. Every experimenter undertook to supply the SCEL with a statement of his power requirements. On the whole, the prospects looked bright for having usable solar batteries available before the end of the IGY. But if so, and if the batteries extended observing time significantly, "then the radio tracking, telemetering, data analysis and computation items in the budget must be correspondingly increased." To prepare for that contingency, the Academy's satellite panel believed $200,000 necessary in the immediate future.
31

John Hagen had earlier suggested that every experimenter or one of his associates should be present at NRL during "the final preparation period" of his apparatus. In any event, two months in advance of a flight he must send the Laboratory an instruction manual explaining how his instruments would work; the field crews would need the manual to learn how to set up the recording mechanism. During the conference, each team of experimenters met separately with the Vanguard staff to draft an explicit agreement about what services the Laboratory would perform, what the outside scientists were to be responsible for. Each team. moreover, reported on the then status of its project. Van Allen and Ludwig expected to have the entire package of their instruments in the Laboratory's test rooms by August. The tape recorder, a source of trouble earlier, was now functioning smoothly, the circuitry working well. Photographs showed the 9-inch cylinder 4.5 inches in diameter containing eight modules encapsulated in foam to provide mechanical rigidity and thermal insulation, the electrical system, and the overall layout. The package weighed 13.41 pounds, the framework 7.09. Testing of the instrumentation for the Lyman-alpha experiment and the environmental studies was also well advanced. Progress on other projects was somewhat slower.32

When the impending start of the IGY brought a number of internationally known scientists to the National Academy in June 1957, the presence of several eminent Russian astronomers and geophysicists added greatly to the interest of the occasion. Contrary to later popular hearsay in the United States, the Soviets talked of their plans, and I. P. Bardin turned over to Lloyd Berkner a document entitled "U.S.S.R. Rocket and Earth-Satellite Program for the IGY." In the section of the exhibit hall given over to the satellite program, reporters clustered around John Hagen and his Russian counterpart. Hagen in answering questions repeatedly spoke of the NRL satellite, whereupon a very junior member of the IGY staff corrected him with "The National Academy's satellite. Dr. Hagen."33 The incident revealed the constant stress the Academy felt obliged to put on the nonmilitary character of the program. July publication of the first issue of the IGY Bulletin served again to remind readers that the National Academy was responsible for the undertaking.

The summer of 1957 was not a time of rejoicing for the men handling satellite finances. The expenses of the Glenn L. Martin Company and subcontractors had increased steadily since October 1956, as indeed had the costs of the scientific parts of the program. Despite the transfer of $5.5 million of National Science Foundation funds to NRL in October 1956 and another $1.862 million in March 1957, the Vanguard comptroller estimated in April that the bill for the entire satellite program would run to $110 million, NRL's costs alone to $96.162 million.34 The Navy budget was not the direct concern of the IGY satellite panel, but it would become so if financial exigencies caused serious slippages in the Vanguard launching schedules, As every setback to the program dimmed the chances of the Academy's winning endorsement of its cherished plans for twelve shots, the USNC secretariat awaited with anxiety the results of the Navy's appeal to Congress.

Thanks to inaugurating in September 1956 a new financial reporting system which required the Martin Company and other NRL contractors to submit detailed cost data monthly, Thomas Jenkins, the Vanguard comptroller, was able to refine earlier estimates; the Laboratory was going to need $34.2 million more than was then available to see the satellite job through to completion. Rather than ask for piecemeal allotments, the Defense Department and the Bureau of the Budget concluded that the wiser course was to seek authorization from Congress to turn over to the Navy the whole amount in a lump sum.35 Jenkins tabulated the figures for the congressional committees:

His figures were all-inclusive, a fact rarely understood, then or later, by people not intimately involved with Vanguard. From the cost of the new radar, the blockhouse, and telemetry equipment-all destined to serve Cape Canaveral for years-to the pay of NRL shop hands for part-time work on Vanguard hardware, every iota of expense was taken into account, even items that a less meticulous person might think properly chargeable to Laboratory or Navy overhead.

The accompanying text gave no precise explanations of why costs for the vehicle, estimated at $28.1 million in March 1956, had risen in fourteen months to $57.111 million, or why the Navy's overall costs, including its work on radio tracking, telemetry, data reduction, and the satellite itself, now in May 1957 seemed certain to exceed $96 million. Yet at hearings in August the Senate Committee was on the whole astonishingly amenable, in spite of nearly universal confusion among committee members over the differences between sums voted to the Science Foundation for the ICY and funds allocated to the Navy for the same program. "We appropriate money to the National Science Foundation," said Senator Magnuson, "and then we appropriate extra money to them for the International Geophysical Year, of which they then gave you some.... Now the Navy is asking for extra money for their part of the Vanguard program, which is part of the International Geophysical Year." John Hagen simply replied: "It never has been very straight in the record." Ten days later Congress authorized the Secretary of Defense to release to the Navy the $34.2 million requested. The hand-to mouth financing of the previous two years need no longer hamper Project Vanguard.37

But money alone could not solve the Laboratory's problems. A measure of the discouragement pervading NRL as summer turned into autumn was an exchange between Rosen and Hagen. "John," said the technical director despairingly. "we're never going to make it in time," to which the older man replied gently: "Never mind! It's a good program, worth following through."38 At Cape Canaveral the TV-2, originally scheduled for flight tests in June, had not left the launch pad at the beginning of October.39

While Richard Porter and the IGY staff at the Academy were aware of the successive delays, when CSAGI gathered in Washington on 30 September for a week-long conference on rockets and satellites, most members of the TPESP knew relatively little about Vanguard tribulations. The panel had not met since l May. At that time news emanating from the Pentagon had been blandly reassuring. Now panel members learned that the flight test of a Vanguard test vehicle with two dummy stages and minus a satellite was set for mid-October. The panel meeting held on 3 October was thinly attended: Lyman Spitzer had resigned; Odishaw, Spilhaus, and Newell were engaged with the CSAGI sessions; Van Allen was en route to the South Pacific. Chairman Porter was worried, but if the other men present shared his unspoken belief that a Russian satellite was nearly ready for launching, they kept their foreboding to themselves. Most of the discussion focused on optical tracking and how to speed up deliveries of the Baker-Nunn cameras, Whipple, to be sure, raised the question of whether the Academy was satisfied with the Vanguard flight schedules, but Porter pointed out that launchings were solely a DoD responsibility. The panel adjourned without pursuing the subject.40 Twenty-four hours later everyone even remotely interested in the American program was asking when the United States would put its first satellite into orbit.


Previous Index Next