Category Dreams, Technology, and Scientific Discovery

During the late 1940s and early 1950s, important advances were made in balloon technology. Large balloon development received a major boost at the Instrument Division of General Mills in Minnesota, Minneapolis. That work was spearheaded by Otto Winzen, Jean Piccard, and others. The ONR supported the developmental work and many flights over a period of years. Those large balloons were known from the beginning as Skyhook balloons.

The University of Minnesota Physics Department was an early adopter of balloons for cosmic ray research. In 1948, they employed them to loft nuclear emulsions and a cloud chamber to make the important discovery of heavy cosmic rays. In late 1949, John R. Winckler arrived and joined the cosmic ray program. Key graduate students associated with that early work included John E. Naugle, who went on to serve with great distinction as a senior official in NASA Headquarters. They also included Frank B. McDonald and Kinsey A. Anderson, both of whom later joined the SUI faculty.

In 1952, frustrated by a number of unexplained early balloon failures, Minnesota scientists Charles Critchfield, Edward Ney, and John R. Winckler undertook a then – classified military project to improve balloon performance. Their primary motivation was to develop a system that could photograph military installations in the Union of Soviet Socialist Republics (USSR). Although development of the U2 reconnaissance aircraft supplanted the need for such a balloon system, a number of the techniques worked out in that program were applied to cosmic ray and other high-altitude atmo­spheric research.12

Two key developments in that developmental project made very large balloons possible. The first was the “natural shape” balloon configuration, in which the inter­nal pressure of the balloon-lifting gas was spread out over the envelope by a network of load-bearing meridional tapes, thus keeping the circumferential stresses within tol­erable limits. The second key improvement was the “duct” appendix. Earlier balloons had been vented at their bases to permit them to valve their excess gas at ceiling altitude. That, however, permitted the premature admixture of air into the balloon envelope, and the balloons would not remain for long at their peak altitude. The new approach used a duct that extended from the base to well up within the gas envelope, so that venting could occur without diluting the lifting gas.

OPENING SPACE RESEARCH

Frank B. McDonald was one of the University of Minnesota cosmic ray researchers who profited greatly from these developments.

his chapter addresses the development of the cosmic ray instrument for the Van­guard satellite program at the University of Iowa. It covers the period from the experiment’s first proposal in 1954 until the launch of Sputnik 1 in October 1957. The launch of the Soviet satellite resulted in a major shift in the Iowa program.

At that point, the decision was quickly made for the army to proceed with a parallel satellite program using their Jupiter C-based launch vehicle. A small portion of the Vanguard instrument that is described in this chapter was extracted to form the very simple primary scientific instrument launched in January 1958 on Explorer I. The full Vanguard package that is described here, with some minor modifications to adapt it to the different launch vehicle and the expanded network of ground receiving stations, was successfully launched shortly thereafter as Explorer III.

Although the instrument was certainly simple by today’s standards, it did mark an important step in the evolution of remotely operated robotic devices in a new en­vironment. Some of the details of this instrument’s architecture and circuit design have been previously described.1 However, an account of the elaborate process of instrument development, testing, and launch, including the many special problems that were encountered, has not been previously available.

Those not interested in the many technical details of developing an early scientific instrument for use in space may want to read the opening sections of this chapter and then move on to the account of the first Sputnik launch in the next chapter.

125

OPENING SPACE RESEARCH

Shortly after the final decision to go the Vanguard route was announced on 9 Septem­ber 1955, the secretary of defense directed the army to stop “all satellite-related study, research, development, and design work” and concentrate on its primary mission, the development of military missiles. With that order, the Huntsville and Pasadena groups lost all official support for further government-funded work on their satellite activities.

Many at Huntsville, Pasadena, and elsewhere (including Van Allen at Iowa) continued to harbor serious misgivings about the Vanguard decision. They be­lieved that the army’s Redstone-based Jupiter C, being much further along in its development, would provide greater assurance of meeting the IGY schedule and objectives.

Thus, although the Orbiter name could no longer be mentioned externally, the basic concept did not die at the working level. Behind-the-scenes actions were undertaken during the next two years to keep that option open. That work continued on three fronts: at the ABMA at Huntsville, at JPL in Pasadena, and at the University of Iowa in Iowa City.

At the Army Ballistic Missile Agency A few days after the decision to commit the United States to the Vanguard approach, General Simon of Army Ordnance registered an angry protest. He asserted that, by fitting the Redstone with the larger scaled-Sergeant upper stages, they could launch an 18 pound satellite as

OPENING SPACE RESEARCH

early as January 1957. However, the navy’s Vanguard contractors—General Electric, Martin, Aerojet General, and Thiokol Chemical—responded with their own assur­ances of quick action, and Simon’s plea got nowhere.19 20

Homer Stewart, who had chaired the committee that had recommended Vanguard, believed that the Vanguard decision was a grievous mistake. Soon after the decision, he traveled to Huntsville, accompanied by JPL director William Pickering and their close associate, Jack E. Froehlich. Their purpose was to discuss how the Orbiter concept might be kept alive. At that meeting, Pickering committed to the use of the JPL scaled-Sergeant rockets as a substitute for the smaller Loki upper-stage rockets to increase the satellite weight capability. In addition, he offered his laboratory’s help in other ways, including use of the supersensitive Microlock telemetry and tracking system that had been developed under Eberhardt Rechtin’s leadership, and with satellite instrumentation, tracking operations, and ground data handling.

Out of those discussions came what they believed to be a “bullet-proof” plan. The RTV that was needed by the Jupiter missile program would be an adaptation of the Orbiter concept. It would be built in such a way that it could be used as a satellite launcher with only minor modifications.

Von Braun called a meeting of his senior staff soon after that meeting. He arrived with his usual beaming smile, saying:

They stopped us in the tracks with our satellite, but we are still in business with our reentry tests. Let’s go to work right away! We will build the upper-stage system for the testing of Jupiter nose cones, which we have been preparing since 1953, and we will launch the first Jupiter C next year, as planned. This will be perfectly legal. In fact, we have to do this anyway for our Jupiter missile project. At the time when we will be called upon to launch a satellite—and I’m sure that time will come—we will quickly add that third solid rocket stage, modify the guidance system, put the satellite on top, and we are in business, and even without transgressing the limitations they have clamped on us!21

When it became clear that some of the 12 Jupiter C test vehicles would not be needed for the nose cone-testing program, von Braun made another noteworthy decision. As reported later by Stuhlinger:

With tongue in cheek, von Braun decided that one of the Jupiter C vehicles should be set aside and carefully subjected to a “long-time storage test”; it was quietly understood that this vehicle represented a potential satellite launch rocket. As soon as permission could be obtained, that vehicle would be taken out of storage, and a third Sergeant stage, an attitude orientation system, and an ignition command receiver would be added. In a parallel action, Jack Froehlich at JPL put a number of [scaled] Sergeant rockets into a controlled environment “to study long-time effects on the propellant,” just in case.22

The master plan and schedule for the fully sanctioned RTV program was prepared jointly by ABMA and JPL in August 1955. The first nose cone reentry test flight was set for September 1956. They tacitly agreed that they could be ready for a first satellite

CHAPTER 7 • THE U. S. SATELLITE COMPETITION 195

launch about a year and a half after that first nose cone test, believing that that would provide sufficient lead time to avoid any conflict with their other programs.

Terminology has sometimes been confusing. Orbiter was the original designation for the four-stage satellite launcher. After the Orbiter project was officially set aside, Jupiter C denoted the multistage Redstone-based configuration, both the three-stage version used for nose cone testing, and, behind the scenes, for the four-stage version used later for the Explorer satellite launches.

The Jupiter C developed for the nose cone testing was also referred to as the RTV. That term was eventually applied to the satellite-launching version, as well. That was especially true during the satellite launch preparations at Cape Canaveral, when it was desired to create a public perception that just another regular Jupiter test launch was in progress.

After the launch of Explorer I, the satellite launcher was frequently referred to as Juno (eventually Juno I) to provide a softer connotation than the perhaps somewhat bellicose-sounding Jupiter name. In Roman mythology, Juno was the sister and wife of Jupiter, god of the sky.

Thus, Orbiter, Jupiter C, RTV, and Juno I have all been used from time to time to identify the Redstone-based satellite launcher. Within the proper context, all are correct.

The Juno name persisted beyond Juno I. Juno II used the Juno I spinning tub arrangement for the upper stages, but the Jupiter rocket was substituted for the Redstone as the first stage to provide a greater payload capability. Any use of the Juno III designation has been lost in obscurity. However, Juno IV was a Huntsville designation for an early concept for the Saturn I and IB, and Juno V referred to an early Saturn V concept.

Following the decision to go with Vanguard, the army continued to send technical information to the Vanguard project office in Washington. Von Braun and his repre­sentatives repeatedly offered to join forces with the Vanguard team. They suggested that a Vanguard satellite could be launched on top of a Redstone rocket, and went so far as to offer to launch the NRL-designed satellite under the Vanguard name, including painting the word Vanguard on the rocket’s side. Stuhlinger carried that offer separately to the Pentagon, to John Hagen (Vanguard project manager), and to Milton Rosen (Vanguard chief engineer). In all three cases, the answer was, “No, thanks.”23

In May 1956, the assistant secretary of defense (R&D) requested of the special assistant for guided missiles in the office of the secretary of defense that ABMA’s Jupiter C be supported as a backup to the Vanguard rocket. The response was that no such plans or preparations would be undertaken without indications of serious

OPENING SPACE RESEARCH

difficulties in the Vanguard program. As those difficulties did not openly surface until later, the request was denied.

On 1 February 1957, in response to a request from the Department of the Army, ABMA responded that the army Jupiter C could accommodate the scientific instru­ments being built for the Vanguard but not the large Vanguard sphere. The instruments could be repackaged fairly simply into a cylindrical configuration to fit the Jupiter C vehicle.

A few months later, in April, ABMA proposed to the chief R&D of the Department of the Army that it orbit, as a backup to Vanguard, six 17 pound satellites with the Jupiter C vehicles. They promised that the first of those would be orbited by September 1957. On 7 May, the Department of the Army formally responded by reiterating that there were no present plans for backing up Vanguard.

As a part of the continuing technical exchange between the ABMA and NRL efforts, General Medaris sent an ABMA satellite capability report to Vanguard’s Hagen in late May or early June 1957. However, on 21 June 1957, the Department of Defense, in the form of a personal visit by their General O’Meara, instructed General Medaris in no uncertain terms that ABMA’s mission was missiles, not satellites. As a result, Medaris felt compelled to recall this ABMA report from the Vanguard office. He later stated in a 1958 congressional inquiry (when the Congress was investigating the U. S. failure to beat the Soviets into space) that “in various languages, our fingers were slapped, and we were told to mind our own business, that VANGUARD was going to take care of the satellite problem.”24

Because of those rejections, and of the direct order to cease satellite work, von Braun felt compelled by mid-1957 to back off on his continuing efforts to obtain Defense Department support for their satellite launcher. Ernst Stuhlinger did not feel quite as constrained. In view of the continuing hints of Soviet progress toward launching a satellite, he attempted yet another appeal in late September. He went first to von Braun, who, stung by the repeated admonitions to stick to their primary mission, quipped, “If you wish to become nervous, do so—but leave me out! I cannot move anyway, as you well know!”

On 27 September 1957, only seven days before Sputnik 1 was launched, Stuhlinger again appealed to ABMA director General Medaris, stating his conviction that the Soviets were close to orbiting a satellite. “A Russian satellite [he said] will soon be in orbit. Wouldn’t you try once more to ask the Secretary for permission to go ahead with our satellite? The shock for our country would be tremendous if they were first into space!”25 Medaris’ reply was, “Now look, don’t get tense. You know how complicated it is to build and launch a satellite. Those people will never be able to do it! Through all my various intelligence channels, I have not received the slightest indication of an impending satellite launch. As soon as I hear something, I will act.

CHAPTER 7 • THE U. S. SATELLITE COMPETITION 197

When we learn something about their activities, we will still have plenty of time to move. Go back to your laboratory, and relax!”26

A week later, Sputnik 1 was repeatedly crossing our heavens with its incessant “beep-beep!” At that point, von Braun asked Stuhlinger, “Did the General talk to you since it happened? I think he owes you an apology!” “Yes,” was the answer. “All he said was: ‘Those damn bastards!’”

During the next two days, news coverage of the event swelled across the country and throughout the world, as editors and reporters rushed to provide their readers with a basic background in rocketry and endless details of the momentous event. Although newspaper coverage was rather sparse in Saturday’s morning papers because of the timing, the afternoon papers were dominated by the news.

In the Sunday morning editions, the press had a field day. Papers across the country devoted much of their front pages to coverage of the event. The New York Times headline read16:

U. S. SATELLITE IS “WORKING NICELY”; Army Ordered to Launch
Another; Also Plans Reconnaissance “Moon”

That paper devoted a substantial number of full pages to coverage of the event.

Not surprisingly, the Florida newspapers were especially effusive. The Tampa Sunday Tribune headline read17:

U. S. SATELLITE WHIRLS 1700 MILES UP

The edition carried 26 different stories covering the event, plus nine pictures, drawings, and cartoons. The articles covered everything from technical details to speculation about future launches.

OPENING SPACE RESEARCH

To illustrate the editors’ obsession with covering the event adequately, one of the paper’s articles was headed:

Florida Roach May Be On New Earth Satellite

It read, “Dr. Richard Porter, a top satellite scientist, was briefing reporters early today on the success of America’s first satellite, Explorer. One reporter wanted to know whether Explorer carried any living matter on the flight into outer space. ‘Not intentionally,’ Porter replied. ‘But maybe a Florida cockroach climbed aboard.’ ”

It was decided by the powers in Washington that our first satellite should be known as Explorer, and the less elegant name Deal passed into obscurity. Many project participants lamented the loss of the satisfyingly uncomplicated name, but the new name was quickly adopted. The Explorer name continued for many years to denote a class of relatively small Earth satellites that pioneered many advances in exploratory space science. Explorer 90 (also known as AIM) was launched on 25 April 2007.

Explorer I with its attached rocket stage was 80 inches in length, of which 34 inches comprised the satellite itself and 46 inches was the final rocket stage. Both the rocket stage and satellite payload were six inches in diameter. The total weight placed in orbit was 30.80 pounds, of which 10.63 pounds was the satellite instrument, 7.50 was its shell, and 12.67 pounds was the exhausted final rocket stage.

The initial orbit ranged from 221 miles height at perigee to 1583 miles at apogee, with an inclination relative to the Earth’s equator of 33.3 degrees. The initial orbital period was 114.7 minutes. The satellite reentered the Earth’s atmosphere on 31 March 1970.

Once the data were recorded as described above, the truly laborious handwork began. Students were employed as part-time aides to read the charts and filmstrips.

For the paper charts recorded by the multitrace pen recorders, data reduction involved first measuring the distances from the beginning to the end of clusters of several cycles of the GM counter scaler output with a ruler. Then the corresponding time intervals were measured, and the GM counting rates were computed from those two numbers. Figure 11.7 shows some of the data readers at their task.

For Explorer I, the counting rates were tabulated, along with the satellite orbital positions that had been computed by the Vanguard Computing Center in Washington, D. C. Eventually, we produced a master tabulation of the Explorer I GM counter rates for all periods during which successful ground station recordings were obtained.32

314

The immensity of the effort required to assemble that tabulation cannot be over­stated. Seventeen ground stations recorded data over the active period of Explorer I operation. That produced a collection of more than 1000 tapes covering the period from 2 February to 16 March 1958. Since the stations started their tape recorders shortly before each scheduled satellite transit, some of the recordings did not contain usable data, because either the station was unable to acquire the signal for some reason or the received signal was too faint and noisy to be useful. Six hundred and fourteen tapes, however, did provide readable signals and were fully processed by the data readers.

That Explorer I tabulation represents a unique record of cosmic ray data above the atmosphere for that period. The document contains an introduction that includes the GM counter calibrations and descriptions of the tables. The second section of 105 pages contains a listing of all recordings. The actual data tables occupy the third section of 824 pages. Each page of the data tables contains from 1 to 28 entries. Some passes were long enough that their data spanned up to four pages. It is estimated that there are more than 12,000 individual data entries in this master tabulation, each with its nominal time, time interval, count, rate, geographic latitude and longitude, and height. In addition, each page contains appropriate general information, such as the station, record number, date, time base correction, and beginning and ending times of the pass, plus the names of the data readers and checkers.

CHAPTER 11 • OPERATIONS AND DATA HANDLING

The data readers exercised their judgment in discriminating, on an inch-by-inch basis, the distinction between data, noise, and other artifacts. Each data interval was measured with a ruler by a reader, then independently by a data checker. In cases of conflicting or other questionable results, a third person, and in some cases a fourth person, checked the readings.

The entire data reading effort was supervised by Anabelle Hudman, an outstanding research assistant who had that as her primary responsibility. The dedicated and long – suffering individuals who read and checked the Explorer I data were, in alphabetical order, as follows:

K. Atit

S. Clendenning C. Horn S. Hwang H. E. Lin W. C. Lin

M. Thornwall M. Van Meter J. Von Voltenburg S. Yoshida A. Zellweger

Sekiko Yoshida was a visitor to the department, on leave of absence from the Department of Physics, Nagoya University, Japan. During her time at Iowa, she was a valued member of the research staff and contributed substantially to the research effort. Wei Ching Lin was a physics student who went on to complete his own research projects, earning his M. S. and Ph. D. degrees in 1961 and 1963. Hseh-Er (Lucy) Lin was his wife. The rest were other students in various campus departments, or spouses of such students.

No account of that huge effort would be complete without a special tribute to the remarkable effort of Evelyn D. Robison in typing the tabulation. At the time, she was a secretary in the Physics Department office and typed all 929 pages on a standard manual typewriter. In hours of poring over the document, I have never seen an error, or even a correction. She was a truly remarkable helper and went on to serve as Van Allen’s devoted personal assistant for three decades.

A few portions of the strip-chart recordings from the Explorer III low-power system were read in a similar manner. However, completion of that effort was overtaken by events. By then there was the realization that a region of unexpected intense radiation existed in space. The Explorer III onboard tape recorder turned out to be ideally suited for examining that phenomenon, and our full attention immediately shifted to reading those data. Further discussion of the reading of the onboard stored data is contained in the next chapter.

It is emphasized that all of this work was done before electronic computers were in general use. We did have access to an IBM 650 computer, which used a combination of

OPENING SPACE RESEARCH

punched cards and patch panel programming. It was limited to 2000 words of storage on a magnetic drum, and the programs were written in Fortransit. That computer was not in routine use for satellite data processing until at least the summer of 1959.33 Although the campus did acquire a series of early large-scale computers during the late 1950s, their punched-card, batch-processing mode made them not very effective for this task.

Initial thinking about the Argus Project was well advanced within classified circles before the mid-March meeting at JPL. Although none of us at Iowa knew of Argus planning by then, we subsequently became aware of it by degrees.9 Faint suspicions of a nuclear testing connection might have been in Van Allen’s mind from the time of that meeting, but it was not until the following weeks that he learned of the activity in any comprehensible terms. During those weeks, Van Allen kept Panofsky updated on Explorer I satellite results by phone and became increasingly aware of the Argus planning.

I made a short stop at Iowa City on 29-30 March following the Explorer III launch. During our get-together, Van Allen shared some of the Argus thinking with Carl McIlwain and me, and we, collectively, began thinking about instrumentation that might support that project, as well as advance our investigation of the naturally occurring radiation. That evolving situation was a major reason for my hasty return to the Iowa campus from my five-month employment at JPL.

Immediately following those discussions, on 31 March, Van mailed Panofsky detailed information about the Explorer III detector and orbital parameters. Since the Explorer I data were not yet understood, and as we had not yet seen any Explorer III data, he made no mention in that letter of observational results, including any hint of the anomalous high-intensity readings.10 Van Allen continued telephone discussions with Pickering and Panofsky during the following week, during which time he first mentioned our growing belief that we were seeing particles trapped in the Earth’s magnetosphere. During those discussions, Panofsky suggested that the high-intensity radiation might have been injected artificially by the Soviets.11

On 9 April, while I was driving back to Iowa City from Pasadena, Van Allen wrote a letter to Panofsky (with copies to Herbert York and Pickering), which contained the first known written reference to our new discovery. Knowing of Panofsky’s suggestion

OPENING SPACE RESEARCH

that the belts might have been produced by the Soviets, Van opened his letter, “It appears that nature (or the Soviets?) may have ‘done us in’ insofar as the contemplated observations [from the Argus detonations] are concerned.”12

We learned later that the Soviets, after first hearing of our trapped radiation dis­covery, thought that the belts that we were observing might have been caused by U. S. high-altitude nuclear bursts. That suspicion, and the reciprocal suspicion by U. S. scientists, was eventually dispelled.

When I arrived back in Iowa City on 11 April, I went immediately to the campus for an updating and strategy session. Discussions between Van Allen, Argus Project personnel, Carl, and me progressed rapidly from that point on. Carl began working on detector designs for what became Explorer IV, and I began laying out its overall system design.

I produced a first complete design layout for the new Explorer IV instrument on 18 April. It included a block diagram showing the array of detectors on which Carl was working and an overall arrangement for the detectors, scaling circuits, and telemetry electronics. It also included a first drawing of the physical arrangement of the instrument package, a listing of its power requirements, and an estimated weight breakdown.13

That information was presented as a specific new satellite proposal by Van Allen at a planning meeting in California the following week. He recommended two GM counters and one counter using a photomultiplier tube to detect the light pulses from a plastic scintillator. The later counter would help differentiate between the natural radiation and radiation produced by the nuclear bursts. A second scintillation detector using a thallium-doped cesium-iodide scintillator was added by Carl soon after to register the total energy deposited in the crystal.

That pivotal California meeting resulted in agreements between Van Allen, JPL and Army Ballistic Missile Agency (ABMA) personnel, Argus personnel, and others on the overall form of the satellite, schedules, and the assignment of responsibilities.

It was at that California meeting that Van Allen rather matter-of-factly stated that we, at Iowa, were prepared to build all the payload instruments. That proposal was accepted with little debate, and Van wrote enthusiastically in his notes, “Agreed: [Iowa] will coordinate payload assembly.”14 That decision resulted in an arrangement whereby the overall payload was designed and assembled at Iowa.

Van Allen called me from California with that news, and with schedule information that would stretch Carl, me, and our helpers to our limits. It called for having a photomultiplier tube in a suitable mounting ready for a vibration test on 3 May, just nine days hence. We were to deliver a full prototype satellite to Huntsville for design approval testing on 1 June and four complete flight payloads on 1 July.

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 367

Van Allen traveled from JPL to Washington, D. C., for further project coordination and other matters. He remained there for most of the following week. On Saturday, he called to discuss a variety of project issues, including the fact that Stuhlinger at Huntsville was quite anxious to work directly with us on the project, rather than through JPL. That eventually resulted in a working arrangement in which we built the full instrument package at Iowa, and the Huntsville people coordinated the interface between the payload and the launch vehicle, performed tests on the satellite that we were not equipped to do in Iowa City, made the launch arrangements, and conducted the launch operations. That arrangement worked wonderfully well.

It was also during the meeting at JPL that Van Allen obtained agreement that the satellite’s orbital inclination would be 51 degrees. That was compared with the 33 degree inclination of the Explorer I and III satellites. We wanted the inclination to be as high as possible so that the new satellites would sample radiation over as much of the region between the north and south auroral zones as possible. Furthermore, a high inclination was needed for observing the Argus Effects. The agreed-upon inclination of 51 degrees was the highest inclination possible for a launch trajectory from Cape Canaveral that would not pass over heavily populated areas.

Although we were already progressing rapidly with actual hardware design, formal approval of the Argus Project, and of our involvement in it, took a little more time. It was on 28 April that Van Allen informed me that we were receiving preliminary funding. The next day, ABMA received a verbal OK from the Advanced Research Projects Agency for their participation in Project Argus and for the State University of Iowa (SUI) role.

The first of May was a hugely eventful day on two fronts—Van Allen announced our high-intensity radiation discovery to the world, and the Argus Project was formally (very quietly) approved.

Immediately following the Explorer I launch, while stepping away from the Explorer I data analysis at Iowa City to continue with the Deal II instrument preparations at JPL,

CHAPTER 16 • SOME PERSONAL REFLECTIONS 439

I was in the midst of a major shift in focus. When I started at the university in 1953, it had been as a physics student, and I took my bachelor’s and master’s degrees in that field. When I undertook the satellite project in 1956 as my graduate research topic, Van Allen and I clearly anticipated that I would develop and prepare the instrument, oversee its launch, and be a major player in processing and analyzing the data and publishing the scientific results.

The decision to switch our experiment to the Army launcher following the Sputnik 1 launch changed that plan. Our agreement with JPL included launching our instrument in two steps. As described earlier, a simple version was launched first in the interest of programmatic speed. That was followed by the launch of our full instrument. Thus, the first U. S. space data were arriving at Iowa City while I was still preparing the second instrument at JPL.

Naturally, we all wanted the Explorer I data to be examined as quickly as possible. Ernie Ray assumed the responsibility for processing the data. Carl McIlwain soon arrived back on campus from his Fort Churchill expedition, and with great enthusiasm and energy, the two of them and Van Allen set about to uncover what that spaceborne Geiger-Muller counter had to report. For the first two and a half months after the Explorer I launch, it was necessary for me to follow that effort from a distance.

A few months later, that situation was prolonged, when the enthusiasm resulting from the successful Explorer I and III flights led to quick approval of the Explorer IV, Explorer V and Heavy IGY Satellite programs, and I had to concentrate on the development of those instruments. Thus, the succession of events led me increasingly away from physics and toward engineering.

The shift soon showed up in my academic progression. At the beginning of the spring 1959 semester, I signed up for the last of the mainstream physics courses that were needed for a Ph. D. degree. Those were highly abstract courses in Quantum Mechanics (being taught by Fritz Coester), Nuclear Physics (taught by James Jacobs), and Relativity (offered by Fritz Rohrlich). They did not come easily for me and, frankly, were outside my area of strongest interest. They were requiring a tremendous effort, when my time was being consumed relentlessly by the satellite instrument development in which I reveled.

At the same time, I realized that a wealth of interesting course work was being offered across the street within the Electrical Engineering Department. Consequently, in the middle of that spring semester, I dropped my physics courses and picked up upper-level courses in Electrical Transients and Pulses (taught by Lawrence A. Ware) and Active Networks (offered by Professor Streib). During the next few semesters, in addition to the standard advanced engineering courses, I set up and pursued sev­eral individually tailored courses to cover topics of special interest. One of those was a course in Radio Telemetry. I studied the topic using the text by Nichols and Rauch6 and then “taught” it to Professor Streib in a series of weekly one-on-one sessions.

OPENING SPACE RESEARCH

Professors Van Allen and Ware, head of the Electrical Engineering Department, embraced the idea of my changing my major and worked with me to make the transition painless.

I was leading the work on the Physics Department’s S-46 satellite as my Ph. D. thesis project when I made the change. That project went forward without pause, and Professors Van Allen and Ware served as my joint thesis advisors. Although the launch failed due to a rocket malfunction, the satellite performed flawlessly, and the work led to receipt of my Ph. D. degree in electrical engineering in August 1960.

Dividing my time between the two departments worked exceptionally well. I have always been pleased that I studied physics first, as it reinforced my inclination to follow the physicist’s basic approach to problem solving.

Much has been written about the distinction between the two fields. One expression of the difference is the somewhat tongue-in-cheek assertion that a physicist builds instruments as a necessary adjunct to pursuing his study of nature, while the engineer studies physics in order to support his love of instrument development. By that measure, I fit best in the latter category.

Throughout my postuniversity years, I have felt that I was somewhat uncomfortably straddling the fence between the two fields. Sometimes I enjoyed the benefits of membership in both “clubs,” but sometimes I felt that I was not a full member of either.

Frank McDonald was born in Columbus, Georgia, on 28 May 1925. He did his undergraduate work at The Citadel and Duke University. In July 1948, just as he was completing work on his bachelor’s degree and looking forward to his graduate studies, the discovery of heavy nuclei in the primary cosmic rays that was mentioned above was announced by Phyllis Freier, Edward Lofgren, Edward (Ed) P. Ney, and Frank Oppenheimer at the University of Minnesota13 and, independently, by Bernard Peters and Helmut L. Bradt at the University of Rochester. That event sparked Frank’s interest in cosmic ray research, and he decided to join the University of Minnesota group.14

For his master’s degree, received in 1951 under the tutelage of Phyllis Freier and Ed Ney, he spent many hours peering through a microscope at cosmic ray tracks in nuclear emulsions spread on glass plates. Through that experience, he developed an uncommonly keen understanding of cosmic ray interactions as they traversed matter. For his Ph. D. degree, he developed and flew a Wilson cloud chamber. That chamber employed a particle telescope consisting of GM counters and a sodium iodide (Na-I) scintillation detector. Whenever the telescope indicated the presence of helium and heavier nuclei, it triggered the cloud chamber expansion, thus permitting the study of the composition and energies of those particles.

Frank joined the Iowa Physics Department as a research associate in September 1953, while still completing a few odds and ends dealing with his Ph. D. dissertation at Minnesota.

He received that degree in 1955 and was appointed assistant professor at Iowa in 1956.

Frank left the University of Iowa in 1959 to play a key role in establishing the space research program in the fledgling NASA. As a member of the initial complement in what became the GSFC at Greenbelt, Maryland, he established the Fields and Particles Branch and its early research program. He moved through a number of positions at Goddard during the next 23 years, ending that period with his service as chief of the High Energy Astrophysics Laboratory. From 1982 to 1987, he served as chief scientist at NASA Headquarters, while simultaneously holding a position as a part-time professor at the University of Maryland in College Park. He returned to Goddard as its associate director and chief scientist in 1987, and served for a time in 1989 as senior policy analyst in the Office of Science and Technology Policy in the Executive Office of the president.

Frank very successfully combined senior-level executive management with his own re­search. Even while serving as the NASA chief scientist, he continued with his personal research program. Having served as principal investigator on 15 NASA space missions, as of 2007, he was still actively interpreting data from the Voyager Deep Space Missions and Inter­planetary Monitoring Platform (IMP) 8 at the Institute for Physics, Science, and Technology at the University of Maryland.

Frank’s first goal upon arriving at Iowa was to continue his investigation of the higher-charged component (charge greater than two) of the primary cosmic rays. He immediately started the development of a new particle telescope for improved measurements of the charge and energy spectra of those heavier primary cosmic rays. It featured a combination of a thin-lucite Cerenkov detector and a three-GM counter array. That arrangement provided better discrimination between the nuclei of different energies and charges than had been provided by previous instruments. The detectors displayed their data on cathode ray tubes in the flight gondolas that were,

CHAPTER 2 • THE EARLY YEARS 35

in turn, photographed by special cameras that Frank designed. I assembled many of Frank’s new electronic circuits as part of my early work at Iowa during the 1953-1954 period.

Frank made his shakedown balloon flight in early 1954 at Goodfellow Air Force Base (AFB) at San Angelo, Texas, only five months after he started this new project. After that initial test, the next step was an expedition to Goodfellow AFB in January

1955 as part of a major two-week international balloon field project. Iowa instruments were carried on 4 of the 13 balloon flights made during that expedition.15 Iowa participants, in addition to McDonald, were William (Bill) R. Webber, Jason Ellis (not to be confused with Robert Ellis, mentioned earlier), Hugh R. Anderson, and Belle Fourche. Cosmic ray instruments from the universities of Chicago and Minnesota and photographic plates from several European universities were also flown on some of the flights.

The balloons, 120 foot diameter Skyhooks, carried more than 100 pounds of instruments per flight. General Mills again furnished the balloons and conducted the launch operations. After floating at altitudes of up to 18 miles, for an average of seven hours, they landed from 50 to 100 miles from the launch site. They were followed in flight by light airplanes and trucks and were assisted by visual sightings from the ground and radio signals to facilitate recovery of the instruments as soon as possible after they landed. Early recovery was not always possible, as the chase parties sometimes had to break off their pursuit because of bad weather and darkness. In most cases, however, instruments were eventually recovered, some of them after they were found by farmers or others at the landing sites.

After that field trip, Frank developed an improved instrument that added a Na-I scintillation detector in a telescope arrangement. The combination of Cerenkov and scintillation detectors provided an improved measurement of the energy and charge for nucleons in certain ranges. The first flight of his new instrument was made from Minneapolis on 7 July 1955, and additional flights followed during the next four years.

Concurrently, Bill Weber developed a Cerenkov-GM counter combination to ex­tend the information on charge composition at low latitudes. He flew it in Texas in

1956 and used those data for his Ph. D. thesis.

Frank McDonald, Bill Webber, Kinsey Anderson, Robert Johnson, and Larry Cahill spent six weeks in February and March 1957 on the island of Guam as partici­pants in an ONR – and AEC-sponsored Equatorial Expedition. The balloon experi­menters, Frank, Bill, and Kinsey, were able to loft only three of their balloon payloads because of strong local trade winds, but they still obtained some useful equatorial data.

Frank and Bill formed a close collaboration during that 1953-1959 period that was the start of an especially durable and fruitful association that has lasted until the present

OPENING SPACE RESEARCH

(2010). Their first joint paper, published in 1959, used the proton data from a number of Frank’s Cerenkov-scintillation detector flights. Ultimately, the pair launched some 22 Skyhook balloon flights. Other joint papers through the years dealt with various aspects of cosmic ray work, including some on charge composition. The instruments gave excellent energy measurements in the range 300-800 MeV per nucleon and complete charge resolution at the higher end of that energy range. The extended program yielded more precise hydrogen and helium energy spectra, their long – and short-term modulation, geomagnetic cutoffs, and the first electronic measurements of lithium (Li), beryllium (Be), boron (B), and heavier elements.

I especially treasure my long-standing and close personal relationship with Frank. His keen understanding of physics and the processes involved in observing cosmic rays was particularly outstanding and personally helpful. He was able to conceptualize and carry out experiments over the years that have added substantially to our understanding of space particle physics. His accomplishments in cosmic ray physics, combined with his outstanding management abilities, made him one of the truly outstanding contributors to the blossoming of space physics during the second half of the twentieth century.

Long before the president’s U. S. satellite commitment in 1955, many researchers had been turning over in their minds ideas for scientific investigations that might be conducted with such carriers. As related in Chapter 3, Van Allen prepared an outline for a cosmic ray experiment in an Earth satellite as early as 1 November 1954, after learning of the army’s thinking about a satellite launcher.2 His objectives, which remained substantially unchanged throughout the subsequently evolving satel­lite program, were “to measure total cosmic ray intensity above the atmosphere as a function of geomagnetic latitude, and to measure fluctuations in such intensity and their correlation with solar activity.” The general description of the basic apparatus, too, remained unchanged, i. e., a “single Geiger-counter, necessary auxiliary circuits, radio telemetering transmitter and antenna.”

Details of the envisioned technical implementation, however, changed dramatically between that earliest outline and the instrument that we began developing a little more than a year later. Van Allen based his early proposal on the use of vacuum tube circuitry, as transistors were not yet available except as purely experimental devices. His proposal did not even mention them. Furthermore, he believed that a transmitter radiating five watts would be necessary for reception at 1500 miles. Those factors combined to focus most of the rest of his discussion upon power supplies to provide the relatively high energy level needed for extended operation. He listed possibilities for the power source as (1) dry batteries, (2) lead storage batteries, (3) Yardney silver cells, (4) hydrogen and oxygen heat of combustion (now known as fuel cells), (5) red fuming nitric acid and aniline heat of combustion, (6) gasoline and oxygen heat of combustion, and (7) solar power. Van Allen narrowed his focus, in that proposal, to the use of a generator driven by a gas turbine fueled by nitric acid and aniline.

The president’s announcement added a sense of reality to the experimenters’ as­pirations, and Van Allen quickly prepared an updated and more complete version of his proposal.3 That one, titled “Proposal for Cosmic Ray Observations in Earth Satel­lites,” reflected some of the new technological developments. On 28 September 1955, less than two months after the president’s commitment, he submitted that new version to Joseph Kaplan, chairman of the U. S. National Committee for the International Geophysical Year (IGY).4

Despite Van Allen’s heavy workload in heading the university’s Physics Depart­ment, it is clear that Van Allen’s thinking and energies were sharply focused on the coming IGY satellite program.

As mentioned earlier, in late January 1956, the Upper Atmosphere Rocket Research Panel, under his chairmanship, held a meeting on the University of Michigan’s Ann Arbor campus to hear and discuss serious satellite research proposals. Among the 38

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 127

papers presented there, Van Allen delivered two containing three specific proposals. His first paper, “Cosmic-Ray Observations in Earth Satellites,” actually contained two separate proposals, the first of which expanded upon his September 1955 proposal.5 It called for the use of a single Geiger-MUller (GM) counter or scintillation detector for a first-time study of the cosmic ray intensity above the appreciable atmosphere on a comprehensive geographical and temporal basis. Specific objectives were listed as “determination of the effective geomagnetic field; the magnetic rigidity spectrum of the primary radiation; time variations of intensity and their correlations with solar and magnetic observations and with the observed intensity of secondaries observed in ground stations; and cosmic-ray albedo of the atmosphere.” He also envisioned that those data would be especially valuable in helping to interpret the observations from the extensive array of cosmic ray ground stations that were being established.

In that proposal, Van Allen included an extended discussion of the effect of limited data recovery by various hypothetical networks of ground receiving stations. Conspic­uously, he did not mention onboard storage, although he and I had seriously discussed that possibility well before the meeting. But our thinking about onboard storage was still evolving at the time of the meeting, and we didn’t add that feature until a little later. That proposal, with the addition of the onboard data storage, was accepted in June 1956 for development.

The second part of Van Allen’s first paper was for the use of a Cerenkov detector to study the relative abundance of heavy nuclei in the primary cosmic radiation. That proposal was soon dropped from further early flight consideration because it could not be accommodated within the severe limitations on instrument weight imposed by the Vanguard launcher. Although not pursued in the initial satellite program, its scientific objectives were eventually achieved by other groups using later satellites.

Van’s second Ann Arbor paper (his third proposal), “Study of the Arrival of Auroral Radiations,” proposed a further study of the auroral soft radiation that had been discovered from the data from the Iowa rockoon flights.6 That proposal also had to be set aside for then, primarily because it required a much higher orbital inclination than was envisioned for Vanguard. Most of the objectives of that second proposal were also achieved with later spacecraft instruments.

Ernst Stuhlinger’s graduate-level training began in 1932 in physics and mathematics at Hans Geiger’s institute at the University at Tubingen, Germany. There he worked under Geiger’s tutelage on developing charged particle detectors and applying them to cosmic ray research. For his Ph. D. dissertation, Stuhlinger developed a variation of Geiger’s counter that was sensitive enough to operate in the proportional region for incident electrons. Stuhlinger used his counter to determine the specific ionization of electrons in cosmic ray showers produced in the upper atmosphere. His postgraduate work included applying his experience with nuclear detectors to helping to clarify the possibilities for building energy-producing uranium reactors in Werner Heisenberg’s laboratory in Berlin.

Ernst’s work in pre-WWII Germany put him in a position, much later, to assist in getting Van Allen’s cosmic ray instruments aboard the early Explorer satellites. There were never many engaged in nuclear physics and cosmic ray research prior to WWII. Those few indi­viduals formed a closely knit community that often transcended national boundaries and the turmoil of the times. During his work in Geiger’s and Heisenberg’s laboratories, Stuhlinger became aware of the work of many of those coworkers. Among them was a young post­graduate researcher in the United States—James A. Van Allen. Some of Van Allen’s early published papers dealt with deuteron-deuteron reactions and the detection of high-energy protons in the presence of fast neutrons. That, of course, was closely related to the work that Ernst was doing in Berlin. Although Stuhlinger kept track of Van Allen’s work in those early days, there was no direct contact between them until much later, when Stuhlinger began working in the United States after WWII.

The rise of Nazism and WWII interrupted Stuhlinger’s nuclear science research in Berlin. Following the German invasion of Russia and eventual setbacks on that front, the demand for additional military manpower for the German Army became overwhelming. In the fall of 1941, Stuhlinger was drafted and sent to the Russian front as a private first class. By early 1943, it was decided that there was a greater need for his physics background, and he was reassigned from the Stalingrad battlefront to the rocket development endeavor at Peenemunde. He remained with the rocket group until the end of the war, with his primary work being helping in the development of the guidance and control system for the A-4 (V-2) rocket.

Stuhlinger was among the group of German scientists who were brought to the United States in 1945 as a part of Operation Paperclip, the U. S. operation to collect components and technology needed to assemble and test V-2 rockets following the German surrender. The captured hardware was accompanied by extensive documentation and more than 100 of the senior scientists and engineers who had participated in the rocket development. Those individuals were very helpful in assembling and firing the captured V-2 rockets in Texas and otherwise assisting in jump-starting the burgeoning U. S. rocket development efforts.

The German group, led by Wernher von Braun and including Stuhlinger as chief scientist, was taken first to Fort Bliss near El Paso, Texas. Many of them moved in 1950 to the

OPENING SPACE RESEARCH

Redstone Arsenal near Huntsville, Alabama. That organization was later reorganized to form the ABMA and, after NASA was formed in 1958, the Marshall Space Flight Center.

Stuhlinger figured prominently in the space program at Huntsville, beginning with plan­ning for Orbiter, the Jupiter C program, and for use of the Juno vehicles for launching Explorers I, II, III, IV, V Beacon 1, Pioneers 3 and 4, Payload 16, Explorer 7, and Payload S-46. In succeeding years, he was active with numerous additional space flights, including lunar exploration flights, the Apollo telescope mount flown on Skylab, the High Energy Astronomy Observatory, various Space Telescope missions, and scientific payloads for the Space Shuttle.

Von Braun, as the director of a large military research and development organization, always had some independent flexibility to conduct limited feasibility studies in areas of high technological interest. After the Vanguard decision in August 1955, he drew upon a special fund earmarked for general research related to the advancement of the art of rocketry for further Orbiter-related studies. Thus, by the time Huntsville was directly ordered to stop all further satellite work in June 1957, theoretical work had been conducted on four capabilities needed to advance from the nose cone-testing Jupiter C RTV to the eventual satellite launcher. They were as follows:

• A new attitude control system to turn and orient the upper portion of the Jupiter C rocket cluster after the end of main-stage engine burning and separation of the forward section from the booster. That had to be done in such a way that the forward section would be exactly horizontal when it reached the apex of the upper-stage cluster flight trajectory.

• Development of a way to determine the exact moment that the forward section reached its apex. The upper-stage rockets would have to be fired at just that instant.

• Working out the celestial mechanics, orbital parameters, acceptable launch times, and injection conditions for the satellite.

• Development of a satellite payload. Von Braun and Stuhlinger insisted from the beginning that any satellite had to be scientifically useful. The satellite would need to accommodate appropriate detectors, a data transmitter, tracking equipment, antennas, and batteries.

After the unambiguous command to stop further satellite development, von Braun no longer considered it prudent to continue use of that source of discretionary funding for this purpose. Even then, however, a number of the Huntsville technical staff enthusiastically continued the work on their own, often during evenings in their homes. Fred Digesu and Hans H. Hosenthein worked out the theory for the attitude control system. Ernst Stuhlinger developed an “apex predictor” to accomplish the second task. Task 3, orbital considerations, was addressed collectively by individuals in Helmut Hoelzer’s Computation Laboratory, Ernst Stuhlinger’s Research Projects Office, and

CHAPTER 7 • THE U. S. SATELLITE COMPETITION 199

Ernst D. Geissler’s Aeroballistics Laboratory. Charles A. Lundquist developed a method for computing the satellite’s orbit based on a limited number of observations from the ground. Josef Boehm, Helmut Pfaff, and their staffs produced designs for the satellite, as described below, as well as designs for mechanical components of the attitude control system.

Admittedly, the distinction between private and official work during that period sometimes became a little blurred. It should be appreciatively acknowledged that Redstone Arsenal commander general Holger N. Toftoy and, succeeding him, ABMA commander general Medaris, “always turned very generously the other way when they visited a laboratory and spotted on one of the drawing boards a sketch that looked suspiciously like a little satellite.”27

A discussion of Stuhlinger’s apex predictor illustrates the character of one of those behind-the-scenes efforts. It was essential that the firing of the solid fuel stages should be initiated at just the right moment. Basic data to assist in that process were available from a variety of radio, Doppler, and radar measurements. The challenge was to pull all of the information together, and to use it in a systematic way to determine the instant when the cluster of upper stages should be fired.

Some of the basic apex prediction concepts were tested during the first Jupiter C reentry test on 20 September 1956. The written plan for that exercise included the statement, “The three proposed methods to determine the apex of a missile. . . will be tested for the first time in Missile #27 [Missile # 27 was the internal identification nomenclature for the first nose cone reentry test vehicle]. Although that missile does not represent an exact duplication of Missile #29 [the vehicle quietly set aside for the first satellite launch], a number of valuable data regarding feasibility and proper functioning of apex determination methods will be obtained. Also, human operators will have the opportunity to familiarize themselves with their tasks. It is anticipated that more practice runs of this kind will be made before the firing of Missile #29.”28 The three methods referred to above were the Radar Method, the Dovap (Doppler, velocity, and position) Method, and a Back-up Method. The plan went on to describe the backup method.

A third and independent method to estimate the expected apex time has been prepared in the following way: velocity signals from the missile fixed gyro-accelerometer, as received by the telemeter ground station, will be directed through a relay circuit to the operator of the apex computer. The signals are recorded by a Brush recorder, together with a time base. They are entered into a time-velocity diagram, which contains, as a reference, the standard time-velocity diagram. The amount of deviation between the two curves is quickly estimated and entered into another diagram, which gives the apex time variation as a function of the velocity deviation.29

That document stated that no great accuracy should be expected from the backup method; it was being implemented in case the other two methods should fail. The

OPENING SPACE RESEARCH

backup method used an approach in which the information was assimilated and combined in a manual process employing prepared charts and other graphical aids. Although it did not use any special equipment, it tested the basic approach envisioned for the satellite launches.

Based on the results from the September 1956 flight, Ernst Stuhlinger developed a form of analog computer to simplify the human operator’s task and to make it more precise. The development of that computer, the apex predictor, was described by Ernst Stuhlinger in the following way:

An electro-mechanical analog computer, called “Apex Predictor,” was developed at Stuh – linger’s Research Projects Office, and built largely at home in his garage, with some help from Wilhelm Angele’s Precision Shop in the Science and Engineering Directorate (because the satellite project did not have an official standing at the Army Ballistic Missile Agency at that time, such work could not be carried out as a normal ABMA activity).30

The apex predictor was built well before the first satellite launch and was tested extensively so that it would be ready if needed for that purpose. It was operated in parallel with other methods during the test of a Chrysler Corporation production Redstone rocket in July 1957 (Missile 37), for the fully successful Jupiter C nose cone reentry test in August (Missile 40), and for another Chrysler Redstone on 2 October (Missile 39).31

Ernst informed me recently that two identical apex predictors were assembled in 1957. Both were used for the Jupiter C launches, one as primary and the other as a backup. Those instruments were lost following the launches, but Ernst built a full-size working replica in his garage during the 1990s.32

The fourth task at Huntsville was to design a satellite that could be launched atop the Jupiter C rocket. The general form of such a payload had been under consideration for some time. Ernst Stuhlinger has recounted that, as early as 1952, as he and von Braun were discussing the prospects for eventually using their Redstone rocket to launch a satellite, Von Braun expressed his belief that they should have a “real, honest-to – goodness scientist” involved in their little unofficial satellite project. “I’m sure you know a scientist somewhere who would fill the bill, possibly in the Nobel Prize class, willing to work with us and to put some instruments on our satellite.” Being fully aware of Van Allen’s work as related earlier, Stuhlinger was ready with his reply: “Yes, of course, I will talk to Dr. Van Allen.”33

As the behind-the-scenes Jupiter C satellite effort progressed during 1956 and 1957, ABMA engineers continued to design the satellite under Ernst Stuhlinger’s general oversight. Josef Boehm and his group of design engineers carried that effort forward at the working level.

The JPL engineers participated actively in that work, with their primary focus being the inclusion of their Microlock system. A key meeting of the ABMA and JPL engineers to plan details of the satellite was held in December 1956. After early 1957,

CHAPTER 7 • THE U. S. SATELLITE COMPETITION

we at the University of Iowa also worked closely with the ABMA and JPL groups to add our cosmic ray instrument to the evolving satellite design, as detailed later.

The culmination of that ABMA-centered, three-party collaboration was a rather complete top-level paper satellite design by the end of July 1957, shown here as Figure 7.1.34

At the Jet Propulsion Laboratory The basis for the ABMA-JPL collaboration had a long-standing background. Through their work on the guidance and control systems for Corporal and other rocket programs, JPL developed an early capability in elec­tronics design. Their interest in electronics was additionally stimulated in late 1954, when the Redstone Arsenal and NRL groups sent their Orbiter proposal to them for comment. JPL immediately became an enthusiastic supporter and participant in the Orbiter work. That involvement made them a bona fide partner in early satellite planning and whetted their appetite for further satellite work.