Category Dreams, Technology, and Scientific Discovery

An ambitious rockoon expedition was mounted in 1955 as a follow-up to the earlier ones. It had three goals. The first was to further clarify the latitude distribution and nature of the auroral soft radiation observed during 1953 and 1954. The second was to continue the original cosmic ray latitude survey by testing a new lighter-weight and even less expensive rockoon. And the third objective was to test a two-stage rockoon configuration in an attempt to reach even higher altitudes.

Frank McDonald was the principal investigator for the first of those objectives and served as the expedition’s team leader. He used the well-tested Deacon rockoon configuration, but with a more advanced instrument that combined most of the features

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of the separate instrument packages flown in 1954. It included the twin-GM counters with different amounts of shielding, plus a scintillation detector generally similar to that used in 1954, but with two important changes. The 1954 detector had been coupled with an additional GM counter to form a telescope to determine the directional characteristics of the auroral soft radiation. Since that radiation had proved to be too soft to activate the telescope, that GM counter was dropped for 1955. Second, a nose cone of somewhat thinner material was used, and the scintillator crystal was located beneath a 0.002 inch thick titanium foil window at the tip of the nose cone to further reduce the amount of shielding in front of that detector. The 1955 instrument package is shown in Figure 2.8 beside its nose cone shell.

I participated in that operation as an undergraduate senior. The preparatory work became all-consuming during the summer, beginning immediately after I finished my spring semester courses. I did much of the design, construction, and testing of Frank’s new instruments. I also developed and set up the associated ground receiving, processing, and recording station used during the expedition to recover the flight data and, upon our return, to process the data for analysis.

FIGURE 2.8 The Deacon instrument pay­load for the summer 1955 rockoon expedition. The scintillation counter is at the top, followed by the two GM counters. Next are two decks con­taining scaling circuits, a deck containing mis­cellaneous electronic circuits, the batteries, and finally, the transmitter. The flat on top of the nose cone contains the thin titanium window for the scintillation detector. The complete pay­load weight was about 40 pounds. (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

It was a special thrill for me to accompany the field expedition in the early fall. The work on that project provided excellent advanced training in the techniques of high-reliability instrument building and scientific field operations that was invaluable when I began designing satellite instruments the following spring.

The second goal of the 1955 expedition was to develop and test a smaller rocket and payload to further exploit the advantages of the rockoon technique. Van Allen had thought that a three inch diameter Loki Phase I rocket might be used in place of the six inch Deacon. He had discovered that a considerable number of those surplus Loki rockets were stocked within the Army Ordnance Department, and some of them were made available to SUI without cost through arrangements by his friend and col­league, William H. Pickering, director of the Jet Propulsion Laboratory in Pasadena, California. Those lighter payloads could be lofted by smaller balloons—39 feet in diameter with a volume of 26,000 cubic feet—which were available at a cost of only about $200. The lighter weight and smaller size of the Loki configuration had another big advantage in that it was easier to handle and launch than the larger Deacons.

Van Allen’s vision was that, if a meaningful instrument could be made sufficiently small and light in weight, a substantial fleet of them might be flown as a part of the SUI scientific contribution to the upcoming International Geophysical Year. When he met with his new graduate students in August 1954, this was among the new ideas

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that he put on the table for consideration as research projects. Carl McIlwain was one of those new graduate students.

The first entry in my notebooks dealing with actual hardware design is dated 27 March 1956.8 On that date, I began breadboarding several transistor circuits that I had found in Electronics magazine.9 Although those circuits served as a starting point, they required far more electrical power than we could afford. I used a binary scaler (variously referred to as a binary counting circuit, flip-flop, or bistable multivibrator) as my learning tool.10 As for the transistors themselves, at first I used several early germanium types that had been identified in the Electronics magazine articles. They gave mixed results, with their high leakage currents making the necessary extreme power reduction problematical. A sample of a new type of surface barrier germanium transistor (Philco type SB-100) arrived at the laboratory on 4 May 1956. It was the first readily available production transistor that had the low leakage current, stability, and uniformity that I needed. I immediately began testing those transistors in my circuits and continued to use them until more desirable silicon transistors became available later that fall.

The Vanguard engineers at NRL were busily developing various electronic circuits and testing components for the satellite program, and they and the experimenters freely exchanged information on our respective efforts.

Instrument development went into high gear in early May 1956. From that date forward, my notebooks are full of descriptions of preliminary, intermediate, and final designs; of meetings attended; and of records of telephone calls to coordinate with the NRL engineers, program managers, IGY officials, and other experimenters. They also record literally hundreds of calls to collect information about suitable components and equipment, including everything from transistors to resistors, capacitors, time standards, recording and playback heads, recording tape, gears, bearings, switches, batteries, circuit board materials, encapsulating materials, and environmental test chambers.11 Those contacts continued throughout the entire duration of the project.

My notebook entry on 9 May contains a rough sketch of the complete block diagram for our cosmic ray instrument. By 10 days later, it had taken the form shown in Figure 5.1.12 By the time Explorer III was launched in 1958, only three major changes were made to that design: a change from a drum to tape as the data storage medium, the addition of a continuously transmitting channel, and a change in the encoding scheme.

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FIGURE 5.1 Block diagram from the author’s laboratory notebook of the University of Iowa satellite cosmic ray instrument as it existed in May 1956 during its development as a part of the Vanguard program.

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May 1956 A meeting of the Working Group on Internal Instrumentation at the Naval Research Laboratory from 31 May to 1 June presented our first opportunity to report on our progress. Homer Newell began that meeting by stating, “We [collec­tively] are entering the brass tacks phase.” He announced that the most likely date for the first launch would be the fall of 1957 and listed the specific national objectives that had been established for the Vanguard program. They were (1) to put an object in orbit around the Earth, (2) to prove that it was in orbit, and (3) to conduct at least one scientific experiment using its internal instrumentation.

In terms of the physical arrangement of the planned Vanguard satellite, He stated that “[the] party line so far is 21.5 lb., 20-inch sphere. Line of retreat—no payload— third stage bottle only—18" dia. x 50" lg.” Following his general introduction, the by-then-active experimenters outlined their individual plans and the status of their developmental efforts.

Our status report included the block diagram shown in Figure 5.1, a full expla­nation of its operation, and a listing of expected characteristics. They included an expected instrument weight of 2.66 pounds (exclusive of the transmitting and receiv­ing equipment and their batteries), sizes and volumes of modules, and a total power requirement of 80.9 milliwatts.13

July 1956 Another pivotal technical working session was held at NRL on 30 and 31 July 1956.14 As far as our Iowa instrument was concerned, the most significant progress included a first attempt to detail the overall physical arrangement, good progress in designing the data recorder and electronic circuits, and investigation of sources for components and fabrication materials.15

Although the initial evaluation of GM counters embraced a wide variety of types, Van Allen’s familiarity with the devices in general, and, in particular, with the halogen- quenched counters that Herbert Friedman had developed at NRL, soon narrowed our focus. Halogen-quenched counters were being produced on a routine basis by the Anton Laboratory in Brooklyn, New York, and Van’s longtime association with the laboratory’s founder, Nicholas Anton, paved the way for a wonderfully effective association. Anton and his chief engineer, Herbert Kalisman, were extraordinarily helpful throughout those early years, when they produced numerous special versions for our evaluation, often within only a few days.

The choice of halogen-quenched counters for the Iowa instruments turned out to be fortuitous. They operated in orbit without degradation for the satellites’ entire lifetimes, in spite of the unexpected extremely high counting rates resulting from repeated incursions into the Earth’s trapped radiation. In retrospect, had we used the more conventional alcohol-quenched counters, they would almost certainly have failed before the end of the satellites’ operating lifetimes because of the high radiation intensities that they encountered.

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Well before the July meeting, I was becoming convinced that a major change would have to be made in the recorder design. The storage medium in the initial Mark I design was a cylindrical drum surfaced with ferric oxide. The recording and playback heads were to be supported above that surface by a very small gap. As the drum rotated, it would move axially, producing a continuous 18 inch long data track as a spiral around the surface of the drum.

I abandoned that drum approach in late June after realizing how rapidly the pulse packing density decreased with increasing head-to-recording-surface spacing. That spacing would have to be as small as 0.5 mil (0.0005 inch), and problems of drum concentricity would be large.16

Using tape instead of the drum permitted the recording medium to ride in direct contact with the heads. The tape version was identified as the Mark II recorder, and by the time of the July meeting, our instrument shop had produced a very rough first unit that I was able to show to the attendees.

The Vanguard technical discussions at the July 1956 meeting included details of the launcher, satellite structure, temperature control, some of the circuit development efforts at NRL, telemetering and radio commanding, and environmental testing. We saw a mockup of the by-then-envisioned satellite structure. Its exterior shell was a 20 inch diameter sphere consisting of two aluminum hemispheres joined at their equator. It was stated that the shell would have a 40 micron coating of silicon monoxide for temperature control.

Internally, the shell contained a small cylindrical chamber at its bottom to house a spring mechanism for separating the satellite from the final rocket stage. A larger cylinder for the scientific instrument was mounted on top of the separation mechanism, supported on its sides by a cantilever structure fabricated from welded aluminum tubing. The model was shown with a 3.5 inch diameter instrument cylinder, and the meeting discussions focused on that size. It was stated, however, that the instrument cylinder could be as much as 6.5 inches in diameter, and it was on that basis that we proceeded with our 6 inch configuration.

One-quarter wavelength antenna rods were mounted on the exterior of the shell’s equator. They were to be folded for launch and snapped into place on tapered me­chanical sockets following satellite separation.

October 1956 The Working Group on Internal Instrumentation held its third meet­ing at NRL on 9 October 1956. By that time, NRL was well along in designing the two different models of the satellite. The first was to contain the 3.5 inch diameter version of the scientific instrument package, and the other was for the 6 inch version.

Throughout the program, Van Allen and I conversed frequently, in his office, the laboratory, the hallways, or over lunch, to review progress and to exchange ideas about the instrument development. It was at just such a discussion on 22 September that we

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agreed to increase from a single to two channels of telemetry, one for continuously transmitting the raw counter rate and the other for transmitting the tape recorder data readout upon ground command.

At that time we addressed the question of possible effects of cosmic radiation on the transistors. Van Allen had become concerned that cosmic ray interactions within the body of the transistor chips might either trigger false results or, in extreme cases, damage the devices. After some back-of-the-envelope calculations, he concluded that reasonably expected cosmic ray rates should introduce less than one interaction in a one cubic millimeter pellet during an entire orbit—an acceptable error rate, even if all of those interactions should result in false counts. He also concluded that the chance of damage to the chips would be remote.

On a different subject, Van Allen mentioned that Wayne Graves, an engineer at the Collins Radio Company in Cedar Rapids, was interested in working on the satellite. He soon made the necessary arrangements with his friend Arthur Collins, and Wayne worked closely with me on the instrument development and testing from that October until June 1957. A very capable engineer, he helped tremendously in the design and testing efforts.

By the time of the October meeting, our work on the satellite instrument had progressed substantially. Major work on electronic circuitry had been completed, and many electronic and mechanical components suitable for flight had been chosen. Silicon transistors from the Texas Instruments Company had entered the picture. Their new 2Nxxx series was coming into early production. I had received early samples and found that their temperature and electrical properties were far superior to the germanium units that we had been using.

Van Allen and I had initially expected that we would contract with a commercial firm to complete the design and fabricate the tape recorders. My telephone discus­sions and visits to several prospective manufacturers proved disappointing, however, and we decided to build them in-house. Our instrument makers had completed the first Mark II recorder, shown in Figure 5.2, and I was subjecting it to extensive testing.

By that time, I had evaluated and ordered the first of a number of new environmental testing facilities. It was a temperature chamber, capable of testing our components and modules at both high and low temperature extremes.

The October 1956 meeting focused on detailed satellite design. A new satellite weight allocation listed 2.00 pounds for the shell, 1.10 pounds for the internal support­ing structure, and 2.50 pounds for our internal experiment packages, including their thermal-mechanical control switches, but not including the telemetering components. The spring device to separate the satellite from the final rocket stage was projected to weigh 1.00 pound. The Minitrack telemetering system, consisting of the antennas, transmitter, and batteries, was estimated at 6.07 pounds. One pound was set aside

for wiring and miscellaneous items. That made a total projected satellite weight of 13.67 pounds.

December 1956 As 1956 was ending, a meeting at NRL of the Vanguard Science Program Committee reviewed the status of the satellite development and worked out additional technical details. By then, we had progressed from general system de­sign to very specific engineering details—the meeting discussions concerned satellite structure, internal temperature control, instruments, the environmental testing pro­gram, and orbit details. The results of internal NRL design work on circuits, batteries, telemetering, and ground receiving station recording received considerable attention.

With respect to our Iowa instrument, by December, the most substantial accom­plishments included extensive thermal testing with our new temperature chamber, finalization of the data-encoding scheme, and more changes to the data recorder.17

My greatest problem with the recorder had been in controlling the speed of the tape during playback. It was necessary to control the speed of the tape to produce

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a reasonably constant data rate for transmission. To initiate playback, a ratchet was released, permitting a spring to rewind the tape onto the supply reel. A normal spiral – wound spring provides a torque that varies considerably as it winds and unwinds. Attempts were made to find a spring formed in an S shape that would provide a more nearly constant tension (a so-called Negator spring), but I was unable to locate a suitable source.

The Mark II version had employed a mechanical governor having centrifugally actuated brake shoes in frictional contact with a stationary drum. That approach could not be made to work smoothly in such a small configuration. For the Mark III version, I used an eddy-current speed controller, where a retarding torque was produced by a silver disk rotating at high speed in a strong magnetic field. Since the retarding torque in such an arrangement varies as the square of the rotational speed, it provided a rough but acceptable speed control. The result was a 6.5 second playback time for dumping the entire tape content, with a speed variation of less than a factor of two during the playback. That speed variation, although certainly not desirable, was compensated for in the ground data processing.

I had been using ordinary consumer-grade Mylar-based recording tape but was concerned about its durability in the space environment. My greatest fear was that the recorder might get warm enough for the Mylar to stretch. I finally located a metal recording tape that had the desired ruggedness and dimensional stability. The UNIVAC I computer that had been introduced in 1951 by the Univac Division of Remington Rand in Philadelphia employed a 0.5 inch wide by 0.001 inch thick phosphor bronze recording tape with an electroplated nickel-cobalt recording surface. Rand donated a twenty-five foot length of that tape. I arranged with the tape’s original manufacturer, the Somers Brass Company in Waterbury, Connecticut, to slit this length of tape to the desired narrow 5/32 inch width. A 55 inch long piece of that tape was incorporated in each Mark III and IV recorder.

The tape-advancing ratchet was also redesigned. The Mark II mechanism had been unbalanced. I was concerned about the effect of vibration, acceleration, and spin on that device and designed a more completely balanced version for the Mark III recorder.

I had had great difficulty in finding very small but sufficiently high performance recording and playback heads. Throughout the summer of 1956, I obtained specifi­cations and samples from every supplier I could locate. In early October, I obtained new samples from the Dynamu Division of Maico Corporation, a maker of consumer- grade reel-to-reel tape recorders. Finally, I had heads that were small enough to fit in the recorder but which still had good enough high-frequency performance to produce the desired data packing density on the tape. The recording head had a gap width of only 0.00015 inch, quite remarkable for that time.

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Other changes in the Mark III version were relatively minor, but they illustrate the extreme care taken to assure high reliability. The three metal idler rollers were replaced by ones made of Teflon, which has a slippery surface. Thus, if a bearing were to freeze, the tape could still slip across the idlers and permit the recorder to operate. Finally, a pair of cam-operated mechanical limit stops was added to augment the previously included electrical limit switches. Then, if there should be an electronic failure, the mechanical stops would stall the tape to assure that it could not be pulled off the tape reels.

It was announced at the December meeting that NRL would deliver a first aluminum prototype satellite shell on 30 January 1957 for our use in test fitting the cosmic ray instrument package and for initial system tests. The first two magnesium models were due on 1 May. One of those was earmarked for our system testing at the State University of Iowa (SUI), while the second (the true prototype model) was to be delivered back to NRL with our instrument package installed for the tests that they were to conduct. Three flight models of the satellite shells and instrument supporting structures were due to us at Iowa City on 15 June.

One important action taken at the December meeting was the naming of spe­cific NRL individuals to work with each of us. The team for our Iowa instrument consisted of Leopold Winkler as chairman, Robert (Bob) C. Baumann for mechan­ical structures, Milton Schach for internal temperature control, Roger Easton for the radio frequency components, and Whitney Mathews for the telemetry system. The group’s initial charge was to review our complete system, prepare a break­down of the relative NRL and SUI responsibilities, and review the SUI instrument budget.

Our transmitters and receivers were also being built by NRL. A first transmitter was promised for 30 January. Their first receiver was due on 15 February. The second transmitter, able to switch between two power levels to accommodate our two-channel instrument design, was due on 1 March. Four flight units of both the transmitters and receivers were scheduled for delivery to us on 1 May.

We scheduled a first vibration test of a prototype data recorder for 1 February. One completely assembled cosmic ray instrument package was due in Washington on 1 May 1957 for environmental testing at the design levels, and three flight models were promised for 15 June.

Henry Richter began his JPL work as a research engineer in Bill Sampson’s New Circuit Elements Group in the Electronics Research Section. This began soon after receiving his Ph. D. degree in chemistry, physics, and electrical engineering in 1955 at CalTech. It took several months for his security clearance to be issued, so Henry was excluded from any involvement in the strange classified work being conducted on the roof of his building. Those were early tests of the embryonic Microlock system by Sampson, Eberhardt Rechtin, and their staffs. Based on those tests, Microlock was written into a feasibility study and, from then on, was included in the army’s satellite planning.

One of Henry’s early assignments, even before receipt of his security clearance, was to “start thinking about batteries that might survive a missile launching, and then operate under conditions of high vacuum and widely varying temperature, and which could function over extended periods while weightless.” It didn’t require a genius to guess what was afoot. As soon as Henry did receive his clearance, he was given part of the satellite feasibility study to work on, and he began to understand more fully the full character and significance of the work. He went on to become a major leader and participant in the development and application of the Microlock system and in the design and building of the early Explorer satellites.36

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Work on development of the Microlock system progressed steadily during the summer and fall of 1955. That winter, Henry Richter, with one of his engineers, William (Bill) C. Pilkington, scoured the country looking for transistors that could operate effectively at the 108 MHz frequency envisioned for the satellites. By March 1956, the system development had progressed to the point where field testing could proceed.

The Redstone RTV booster rocket contained several measuring and telemetering systems to provide information about the performance of its control system and motor. None of those, however, provided information about the flight performance of the high-speed stages, most notably, temperatures in the nose cone during its reentry through the atmosphere. Two Microlock transmitters operating at different power levels were placed in the test vehicle for that purpose. They flew on the first all-up RTV flight that September.

Four Microlock ground stations were set up to support that first launch. Although they were justified because of their need for the nose cone-testing program, the selection of ground sites was substantially influenced by the anticipation that the system could later be used for satellites.

A station at the launch site was, of course, essential. It was needed to help with the checkout of the flight equipment before launch and during the rocket ascent. A second station was set up at Huntsville. That location was within the circle of visibility for much of the trajectories of the Jupiter C nose cone test flights. The existing Sergeant­testing station at the White Sands Proving Ground in New Mexico was refitted for the Jupiter C nose cone test flights, as over half of their flight trajectories were visible from that location. Being in an area that had less radio interference and that was at a greater distance from the flight trajectory than Huntsville, it yielded a better measure of system performance applicable to later satellite flights.

A fourth Microlock station served primarily as a site for Microlock developmental field experiments. JPL conducted their first system tests by helicopter overflights in the Pasadena area in early 1956. It soon became necessary to make more sensitive and discriminating tests, for which the entire Los Angeles area had far too much radio interference. After extensive surveys, they settled on a location somewhat north of the midpoint of a line between San Diego and El Centro, California. Near the Anza – Borrego Desert State Park, it is located in a valley known as Earthquake Valley, with mountains to the west, north, and east. That nearly ideal location very effectively cut off radio interference from all heavily settled regions.

The Earthquake Valley test station was established in early 1956, and helicopter overflights were conducted there during March. The engineers at those tests, including Cliff Finnie, Bill Pilkington, Phillip (Phil) Potter, Henry Richter, and Robertson (Bob) C. Stevens, demonstrated that the system would be capable of conveying data from a satellite or space probe from over 20,000 miles away.

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For the Jupiter C ABMA-JPL collaborative effort, including both the RTV testing and their behind-the-scenes satellite work, the many groups at Huntsville and Pasadena worked together very harmoniously. The combined efforts required a highly interac­tive and iterative process, with every change affecting many other parts of the program. Frequent meetings helped to keep the work closely coordinated. Both laboratories de­veloped great respect for their counterparts. There were, of course, disagreements that required high-level decisions. Most of those were worked out directly between the two project managers: von Braun at Huntsville and Froehlich at Pasadena. Their decisions were accepted and implemented with goodwill.

Another undercover satellite effort The JPL participation in the ABMA-JPL col­laboration, including the integration of their Microlock system in the ABMA-designed satellite, was not the whole story. Apparently unknown to their ABMA counterparts, JPL undertook, at the same time, the design of their own version of a satellite for launch on the Jupiter C.

To step back a moment in time, the JPL had actually entered the competition for scientific payload space very early in the IGY satellite program, when they began working out the details of their own cosmic ray experiment proposal. Pickering first wrote about it to Van Allen (the latter as chairman of the Working Group on Internal Instrumentation) on 5 July 1956. His plan was formally submitted to the IGY over Eberhardt Rechtin’s signature on 26 July 1956. The proposal included three parts:

(1) an ion chamber for cosmic ray research by Victor Neher on the CalTech campus,

(2) photoelectric photometry of the sky by William Baum, an astronomer at the Palomar Observatory, and (3) an engineering-related data transmission and reception experiment to study their Microlock system performance by the JPL engineers.

That proposal was given for action to Van Allen’s Working Group on Internal Instrumentation that the U. S. National Committee’s Technical Panel on the Earth Satellite Program had established to deal with Vanguard experiment proposals. The Working Group on Internal Instrumentation identified it as Earth Satellite Proposal 27 (ESP 27) and assigned it a Priority B rating at their 11 October 1956 meeting. Not being included on the highest priority list, the IGY program did not provide funding and approval for further development.

The planning for it remained active at JPL, however, until at least 9 May 1957, when Richter made a trip to NRL to discuss the integration of ESP 27 into the Vanguard satellite.

Early thinking at JPL was that their instruments might be included in a satellite of their own making. That claim is substantiated by the appearance, in a CalTech-issued magazine in the summer of 1957, of an article by Pickering describing “how the lab could ‘completely instrument one of the [Jupiter C] vehicles’ with a cosmic ray

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experiment developed by a CalTech professor and another instrument from a Palomar Observatory astronomer.”37

By April 1957, JPL had shifted from that approach to focusing on our University of Iowa cosmic ray instrument instead of their own instruments. It had the advantage of being a Priority A instrument in the Vanguard instrument lineup and therefore of having the full endorsement and support of the U. S. IGY program. The fact that we had designed it to fit either the Vanguard or the Jupiter C configuration also figured in their thinking. Those factors led to the visit by Eberhardt Rechtin to Iowa City on 23 May 1957, as discussed in more detail in the next section.

By the time of the Sputnik 1 launch in October 1957, the JPL satellite development had progressed to the point that considerable prototype hardware had been built. The low-power transmitter assembly that I saw soon after my arrival at JPL in November was one physical manifestation of that situation. Models of the complete satellite later found their way into various museums, including the Griffith Observatory in Griffith Park, Los Angeles.

At the University of Iowa We at the University of Iowa Physics Department became involved in the various Jupiter C satellite-launching planning efforts through a long chain of events. Ernst Stuhlinger had been generally aware of Van Allen’s research even before the beginning of WWII. The two first met during the immediate post- WWII period, after Stuhlinger had arrived in the United States. Van Allen, by then a young upper atmosphere scientist at the Johns Hopkins Applied Physics Laboratory, was flying cosmic ray instruments on some of the V-2 rockets that had been brought to the United States. Stuhlinger was coordinating the interface between the rocket engineers and the researchers.

As mentioned earlier, Stuhlinger suggested to von Braun in 1952 that Van Allen would be a good choice of an experimenter to place a scientific instrument on the satellite that they envisioned. Stuhlinger and Van Allen first discussed that subject when Van Allen was at Princeton University on leave from the University of Iowa in 19 5 3—19 5 4.38 During a visit there with Van Allen in mid-1954, Stuhlinger described the ABMA thinking about a satellite, emphasizing the opportunity to fly Geiger counters. Stuhlinger later related:

When I had finished my sales talk and waited for Dr. Van Allen’s show of interest, he only said, “Thanks for telling me all this. Keep me posted on your progress, will you?”—I was disappointed by this apparent lack of interest, but then I remembered from our meetings at White Sands that Dr. Van Allen was a very cautious scientist, far too careful to jump to any conclusions. So I understood his restrained response, and I kept him posted on our progress. Von Braun informed Dr. Pickering, at that time Director of the Jet Propulsion Laboratory, of our contact with Dr. Van Allen, and received the latter’s full endorsement of our step.39

That discussion had the effect of heightening Van Allen’s excitement about the prospects for extending his cosmic ray research farther into space.40 He immediately

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prepared an outline for a satellite-borne cosmic ray experiment and sent it to Stuhlinger.41

A year later, soon after President Eisenhower’s announcement of the U. S. intent to launch a satellite, Van Allen updated that proposal and submitted it to the U. S. planners of the IGY endeavor.

At that point, I had just returned from the summer 1955 rockoon expedition to northern Greenland and was completing the work for my bachelor’s degree. I would soon need a graduate research project. Van Allen and I began discussing specific details of the satellite instrument, with the general understanding that its development and flight might serve that purpose.

The discussions between Van Allen and Stuhlinger figured importantly in arriving at the physical configuration of the Iowa cosmic ray instrument package, even while it was being designed for the Vanguard launch vehicle. The NRL initially specified that their 20-plus inch diameter spherical satellite would contain an internal instrument cylinder 3.5 inches in diameter.

Van Allen stated his preference that the overall form of the satellite should be a right circular cylinder approximately 6 inches in diameter and 18 inches in length. He believed that that configuration would provide the most efficient packaging for the scientific instruments. Since that had been the diameter of the instrument payloads that we had built for the Deacon-based rockoons, our laboratory had extensive experience with that particular envelope.

Van Allen formally expressed that preference in a letter to the Technical Panel on the Earth Satellite Program in late January 1956.42 Specifically, he proposed that half of the IGY payloads be built in the original 20-plus inch diameter spherical form, identified as Mark I, and that the other half be of a new Mark II configuration, in the cylindrical form that he preferred.

The Vanguard program staff responded with a compromise—by changing their specifications to permit either a 3.5 or 6 inch instrument package to be housed within the outer 20.5 inch diameter spherical shell. Although not going as far as Van Allen wished, that change did allow us to use the six inch form factor in developing our cosmic ray instrument.

Beyond any doubt, Van Allen’s preference for the six inch package was strongly in­fluenced by his knowledge that the Redstone-based vehicle could accept that package with little change, if problems should develop with the Vanguard launch vehicle.43

Stuhlinger told Van Allen about the first fully successful test flight of the RTV during a telephone conversation on 16 November 1956, about two months after its occurrence. During that discussion, he expressed his continuing grave doubts about the realism of the Vanguard launch schedule and encouraged Van Allen to suggest a specific

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cosmic ray instrument that could be used in the Jupiter C payload. Van Allen did that informally during the discussion and followed it on 13 February 1957 with a letter proposing a specific instrument package. Part of his letter read:

Dear Ernest [sic]:

1. We are delighted to know that there is a possibility of flying some scientific apparatus on one or more of your orbiters. . . .

It is my understanding that a total payload of 15 pounds is now regarded as feasible. In consideration of what types of scientific apparatus may be appropriate I have taken two pounds as a reasonable weight. And, of course, I have depended rather heavily on the considerations in which our I. G. Y. Working Group on Internal Instrumentation has been engaged for over a year.

I have assumed no data storage of the type which requires command readout and have also assumed that the I. G. Y. 108 mc/sec telemetering stations will be available, or that a substantial Microlock array will be available.44

The letter continued by listing all of the experiments being considered for the Vanguard program. Those, in addition to Van Allen’s cosmic ray experiment, were experiments dealing with solar ultraviolet and X-ray fluctuations, meteoric erosion, air density, the Earth’s radiation balance, cloud coverage, and ionospheric measurements. The letter closed:

4. Needless to say, our group here at the State University of Iowa is very eager to participate in your program. We now have all the appropriate elements of a suitable cosmic ray apparatus well developed, as well as the foundations for interpretation of the observed data. We can make several sets of flight gear (See enclosure) within about a month after receipt of definite packaging details. The only other significant factors which are not presently known to us are the impedance, voltage and pulse width of our signal for modulating the transmitter.

The enclosure to Van Allen’s letter included my initial block diagram, drawings of some of the mechanical details, and data pertaining to the weights of components, permissible operational temperature range, and sensitivity to vibration.

That marked the beginning, in early 1957, of our direct participation in the col­laborative ABMA-JPL satellite effort. During April and May, in a continuing series of exchanges with ABMA personnel, we worked out further details of the satellite instrument. Stuhlinger, Joseph Boehm, Charles Lundquist, and Arthur Thompson vis­ited Van Allen, Frank McDonald, and me at Iowa City on 19 April 1957, where they provided a full description of their then-current thinking about the satellite design. The information developed at that meeting made it possible for me to send an even more detailed description of our thinking to Josef Boehm at ABMA on 3 May. My letter read, in part:

The block diagram of the cosmic ray experiment would remain as in Dr. Van Allen’s letter of February 13, and is enclosed as figure 1.

The equipment would be in the form of three units, not counting the transmitter or any power supplies.

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1. G. M. tube. Anton type 316 counter tube.

2. Module #1. G. M. tube driver and scale of 32.

3. Module #2. H. V power supply and modulator.

… The form of the modulator is not yet known, but will have to be worked out with JPL. We propose to telemeter the collector voltage of the final scaler.45

These exchanges peaked when I went to Huntsville on 10 and 11 July 1957 with portions of my then-existing Vanguard hardware and plans for an extended working session. We developed remaining details of the ABMA-JPL-State University of Iowa (SUI) collaborative satellite design, and I left that meeting with three drawings that showed the satellite’s overall physical layout and several design details. The key drawing from that session was shown earlier as Figure 7.1.

During exchanges with the ABMA people at Huntsville, there were a few tentative discussions about including our more complete instrument, including its onboard data storage as developed for Vanguard, in a second version of the satellite. That went as far as Stuhlinger’s agreement during a telephone conversation, to check into the possible use of the NRL command receiver. The idea soon died, however—there is no further mention of it in my notes.

As mentioned before, Eberhardt Rechtin from JPL visited us in Iowa City on 23 May 1957, at the same time that I was working diligently on instrument design details with the Huntsville people. He and I discussed the simple version of our satellite instrument that had evolved by that time, and details of their Microlock design.46

To this day, it has not been possible to determine whether that solo visit by Eberhardt was primarily in response to the paragraph in my letter of 1 May quoted above or whether I was being unknowingly drawn into the separate JPL effort to build their own version of a satellite in competition with ABMA. Since JPL had been a direct participant in the collaborative ABMA effort, I assumed that he was following up on my 1 May suggestion that we work out further details of our instrument’s interface with the Microlock system. I am convinced that Van Allen also believed that the Rechtin visit was part of the ABMA-JPL-SUI collaborative effort. It is entirely possible, however, that one of Eberhardt’s major objectives was to gather information about our instrument that they could use in their own satellite design. Perhaps he had both objectives. Certainly we at Iowa were unaware of the separate JPL satellite development effort, and there is no evidence that von Braun and his staff at Huntsville knew about it until November.

My next direct exchange with the JPL engineers did not occur until 22 October, when I received a call from Rechtin to set up a meeting. Discussion of that and following events is resumed in the next chapter.

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Even in Hollywood Three years after the Explorer I launch, a story appeared in the press that indicated that Hollywood nearly got into the act. A Metro-Goldwin-Meyer producer, Andrew Stone, related the story in June 1960, and it was authenticated by Lieutenant General James M. Gavin (army R&D chief at the time) and William Pickering, the JPL director. The story went like this:

Andrew Stone was commissioned by his employer in 1957 to make a movie on guided missiles. After talking to people at a number of missile research installations, he had a lengthy conversation with Pickering, and Pickering told him of the U. S. competition with the Soviets to be the first in space and that the United States could beat them by putting a satellite into space within 90 days with the army’s Jupiter C vehicle.

That energized Stone, who told him that he not only would produce the mil­lion dollars needed for the satellite but that his organization would provide four million more to buy the rocket. Pickering, recognizing that his hands were tied by the interservice rivalry, suggested that Stone take his offer to the Pentagon brass in Washington.

Stone did so, with great frustration. He could find no one in the Pentagon who seemed to be aware of the possibility. One Defense Department official told him that the job would require at least $18 million, justifying his claim by explaining that the navy had already spent that much on it.

After finally getting a firm rejection, the offer died. This occurred in May, about six months before the Soviets launched Sputnik 1.47

I left Pasadena with Henry Richter for Washington on Thursday, 20 February, to deal with the ground station readiness problem.8 Finally, on Saturday, over a week before the scheduled launch, I was on my way from Washington to Florida. After hitching a ride from the Orlando airport to Cocoa Beach with Roger Easton, Marty Votaw, and other NRL personnel, I checked in at the Sea Missile Motel. Early on Monday morning, I joined the JPL and Army Ballistic Missile Agency (ABMA) crews at Cape Canaveral and we all worked, steadily and methodically, to prepare for the second Jupiter C launch.

Being at the Cape for a full 10 days during the preparations for the initial Deal II launch attempt, I received an extraordinarily complete and exciting exposure to the myriad activities involved in launching a large multistage rocket. With the countless components that had to work together flawlessly, the handling of highly corrosive fuels and cryogenic oxidizers, and the pushing of the state-of-the-art in materials and electronics, I still marvel that it was possible to launch the first satellites at all.

270

Cape Canaveral was an isolated piece of real estate before it was tapped for its rocket-testing mission. A nineteenth-century lighthouse is still located near its tip. The few early inhabitants had to contend with swamps and myriad pests, including coral snakes and rattlesnakes, wildcats, deer, armadillos, alligators, and, of course, the always troublesome swarms of mosquitoes.

The first rocket launches from Cape Canaveral had taken place on 24 and 29 July 1950. They were of the two-stage combination of the German V-2 boosters topped by JPL WAC Corporals, the so-called Bumper rockets. They took place from a site, later identified as Launch Complex 3 but long since dismantled, near the lighthouse.

The evolution of the complete Cape Canaveral and Merritt Island area into the massive complex of today is a fascinating story in itself. The layout of the portion of the Cape that was active in 1958 is shown in Figure 10.3.

CHAPTER 10 • DEAL II AND EXPLORERS II AND III 271

The satellite preparations at Cape Canaveral were centered at the Spin Test Facility, located not far from Launch Complex LC-26, from which the Deal satellites were launched. The Spin Test Facility was a simple blocklike structure containing a single large bay with a high ceiling. It was built for the express purpose of stacking and checking the Jupiter C second-, third-, and fourth-stage solid rockets. The satellite received its final assembly and electrical checkout in a trailer just outside the Spin Test Facility. It was then carried into the Spin Test Facility, subjected to a payload spin test, and mated with the final rocket stage. That top assembly was spin tested, and then mated to the rest of the rocket cluster. Finally, the composite second-, third-, and fourth-stage assembly was balanced and spin tested.

The roof of the Spin Test Facility served as a wonderful observation post. It placed us in the open above the scrub growth so that we had a clear view of all launches then being conducted at the Cape. The Redstone and Jupiter pads with their blockhouses were just over a mile away. The Thor site was only one and a half miles away, and the Vanguard site was one and three-quarters miles distant. The Atlas pads were taking shape in Intercontinental Ballistic Missile (ICBM) row about four miles away. (The Titan pads shown on the map had not yet been built in early 1958.)

From the vantage point of the Spin Test Facility roof, during 1958, we observed a steady parade of launches, of both spacecraft and military rockets. This was a truly overpowering experience, even if not very wise, as we were so close that a stray missile would have been impossible to dodge. Sometime later that year, Cape officials moved the security line farther back when launches were scheduled, and we had to do our recreational watching at a roadblock somewhat farther away.

Even there, the launches were spectacular beyond words. The sense of unleashed raw power as the vehicles lifted from their pads and arched into the blue or nighttime sky was awesome, indeed. During my many visits to the Cape from 1958 through 1965, I watched launches of Bomarc, Matador, Navaho, Snark, Polaris, Juno, Thor, and Atlas rockets. Many were failures. On one occasion, I observed a particularly memorable show—an evening launch attempt of a Thor by the Air Force. It exploded only a few thousand feet into the air. The resultant burning of aluminum and magnesium parts lit the nighttime sky like a monstrous flare, so bright that objects on the ground were as clearly visible as though it were daytime.

To my great disappointment, I was never able to witness a Saturn or Shuttle launch, but by extrapolation, I can imagine the intense sensations of hearing and feeling that must be conveyed by the launch of those much larger vehicles.

Back to Deal II: the JPL satellite payload crew and I concentrated on the detailed checkout of the three identical flight instruments. Those tests included electrical performance, spin, and radiated power tests. For some of those tests, we used a

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special interrogation station set up in the nearby Atlas Radio Inertial Guidance (RIG) area. For all three payloads, I read and analyzed a seemingly endless stream of data recordings, concentrating on the performance of the onboard recorders. Although some of the tests used radioactive sources to stimulate the GM counters, others required extended periods to register the less frequent natural cosmic rays.

We also performed a major radio frequency interference test by mounting the Spare Payload atop the fully assembled multistage rocket in its launch gantry. During that test, we displayed the instrument’s signal, both in real time from the test-site receiver and post facto from data recordings made at the fully functioning ground station located some distance away. Part of that test included interrogating the onboard data recorder via the transmitter at the RIG site. Those tests worked well. Unfortunately, we were not able to spin the tub containing the three upper rocket stages and instrument atop the Redstone booster. That omission resulted in considerable anguish later, during the actual launch countdown.

On Monday and Tuesday (the two days before launch), I briefly summarized the results of the complete array of tests on all three payloads in my notebook.9 Flight Payload 1 was “no good,” with much skipping of the data tape recorder’s toothed ratchet. Flight Payload 2 and the Spare Payload were both generally satisfactorily, although there were some conditions under which the Flight Payload 2 data recorder also skipped.

It was at that time that I learned with tremendous relief that NRL had completed and tested all of their interrogating ground stations.

On the day before launch, it was time to make a final decision on the selection of the flight payload. Since Flight Payload 1 was not acceptable, it was a question of whether to fly Flight Payload 2 or the Spare Payload. Milt Brockman, the JPL payload manager, strongly preferred Flight Payload 2. It had been fully assembled and tested back at JPL, whereas the Spare Payload had been finally assembled at the Cape and had received less testing. Furthermore, a thermistor substitution had been made in the Spare Payload, and that component had not been as thoroughly calibrated. I had a slight preference for the Spare Payload, as the tape recorder operation was more dependable. I noted, “The tape recorder [in the Spare Payload] does not skip when jarred so easily. P. L. [Payload] II is quite bad in this respect. However it seems to be OK when kept still.” After lengthy discussions, I reluctantly acquiesced to Brockman’s recommendation, and Flight Payload 2 was selected for launch. That payload is shown in the photographs of Figure 10.4.

The cosmic ray experiment that led to the radiation belt discovery was the one that Van Allen first proposed in November 1954.6 Its objectives were “(a) To measure total cosmic ray intensity above the atmosphere as a function of geomagnetic latitude and (b) To measure fluctuations in such intensity and their correlation with solar activity.”

Less than a year later, on 25 September 1955, and less than two months after Eisenhower’s announced decision to include a satellite program as a part of the U. S. contribution to the International Geophysical Year (IGY), Van Allen submitted a revised and extended version of that proposal to Joseph Kaplan, chairman of the U. S. National Committee for the IGY. The first paragraph of that letter read, “There is enclosed a ‘Proposal for Cosmic Ray Observations in Earth Satellites.’ Recent discussion with Dr. G. F. Schilling has indicated that it is appropriate to submit definite proposals at this time.”7 He followed that letter with a further-expanded version that he presented at the forty-third meeting of the Upper Atmosphere Rocket Research Panel at Ann Arbor, Michigan, on 26-27 January 1956.8 The latter proposal was eventually accepted as the basis for our development of the Vanguard cosmic ray instrument.

The January 1956 proposal stated its general objective as a “study of the cosmic-ray intensity above the atmosphere on comprehensive geographical and temporal bases for the first time.” It included extended discussions of the interpretation of expected data with respect to (1) the effective geomagnetic field, (2) the magnetic rigidity spectrum of the primary radiation, (3) time variations of intensity, and (4) cosmic ray albedo of the atmosphere.

Cosmic ray albedo refers to particles that leave (splash out from) the Earth’s atmo­sphere as a result of nuclear interactions caused by primary cosmic rays crashing into the atmosphere from above. Van Allen’s paper included a figure that plotted

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lune-shaped regions in the Earth’s vicinity within which particles of particular mag­netic rigidities and traveling in certain directions might be trapped.

That drawing and its discussion reflected the fact that there had already been a substantial body of earlier study into the behavior of charged particles in the Earth’s magnetic field.9 Sightings of the aurora Polaris (aurora borealis, popularly the northern lights, in the north polar region and aurora Australis in the southern hemisphere) had been recorded for centuries. A substantial amount of theoretical and experimental work was done during the first half of the twentieth century in attempting to explain those aurorae. Many of those early studies were conducted in Scandinavia, quite naturally, since populated portions of those countries lie well within the northern auroral zone. Kristian Olaf Bernhard Birkeland (1867-1917) was one of the leading early auroral researchers and, even today, is considered one of Norway’s greatest scientists. He published the first realistic theory of the north­ern lights, including his belief that they resulted from charged particles ejected from the Sun that were somehow captured or focused by the Earth’s magnetic field.

To help prove his theory, Birkeland performed his famous torella experiment. He directed an electron beam toward a conducting sphere that had a dipole magnetic field. The sphere’s surface was sensitized, and the experiment was conducted in near­vacuum. Electrons were seen to hit the sphere primarily in two rings that suggested auroral ovals similar to those seen on Earth.

With that finding, Birkeland asked his former teacher, Jules Henri Poincare (1854­1912), to examine the motion of electrons in magnetic fields. Poincare was able to solve mathematically the problem of the motion of charged particles near a magnetic monopole. Although magnetic monopoles have not been seen in nature, his work showed convincingly that the electrons were guided toward the poles of a real dipole magnet, thus preparing the way for later work. Birkeland suggested this problem to a mathematician friend, Carl Fredrik Mulertz Stormer (1874-1957), who devoted much of his career to its further study.10

One of Stormer’s most important contributions was to show that, for electrically charged particles of various combinations of mass, charge, and vector velocity, two dynamical regions exist within a dipolar magnetic field such as that of the Earth. One is of unbounded motion, and helps to account, for example, for the arrival of particles from outside the Earth’s immediate neighborhood (from the Sun, for example) into the Polar Regions.

The second region is one containing bounded trajectories. Stormer showed that certain classes of charged particles can spiral around the magnetic lines of force and that, as their centers of motion move north or south, they are reflected by the converging magnetic field lines. Moving then toward the opposite pole, the same action takes place, and the particles continue to mirror back and forth between the poles until

CHAPTER 12 • DISCOVERY OF THE TRAPPED RADIATION 323

they are scattered by irregularities in the magnetic field or interactions with other particles.

It is clear that the early researchers tended to view the region from the outside in. That is, they envisioned the particles as approaching the Earth from the Sun and beyond, and they referred to the region of the magnetic field that we now refer to as the trapping region as the forbidden zone, i. e., a region within which particles from the outside could not enter. Although they certainly realized that a particle injected by some mechanism into that zone with the proper rigidity and direction could be reflected back and forth by the action of the magnetic field, they did not appear to harbor any expectation that there might be a substantial reservoir of particles durably trapped there.

We at the Iowa campus enjoyed a special treat during the first semester of the 1954— 1955 school year, when Sydney Chapman joined us as a visiting distinguished pro­fessor. During that semester, Chapman taught a course titled Physics and Chemistry of the Upper Atmosphere. Among other things, he included extended discussions of the aurorae, and of theories that attempted to describe them, including the works of Birkeland and Stormer. Detailed notes from his lectures were assembled by Ernie Ray as a mimeographed, unpublished compendium.11 The formal course was accom­panied by many stimulating informal discussions by Chapman, the faculty members, and us students.

Interest in the trajectories of charged particles in the Earth’s geomagnetic field, especially after the interaction with Chapman, resulted in a flurry of activity within the State University of Iowa (SUI) Physics Department. Ernie Ray and Joe Kasper undertook concentrated studies of that phenomenon. With Van Allen and others, they began to apply that knowledge to help explain the auroral soft radiation that had been detected, first on the 1953, 1954, and 1955 rockoon expeditions, and then by Carl McIlwain with his rocket shots at Fort Churchill, Canada, in 1957-1958.

In their studies, which involved tracing the charged particle motions near the Earth, Ernie made some of his earliest attempts to program the newly evolving digital computers to solve the differential equations involved. Joe configured the analog differential analyzer that he had developed for his master’s thesis for a similar purpose.

During that period, there were many spirited discussions of Stormer trajectories, cosmic ray motion, auroral mechanisms, and other related topics, both on our campus and within the larger research community. The field was abuzz with activity, both experimental and theoretical.

S. Fred Singer, as early as April 1956, suggested that the motions of charged particles in the Earth’s magnetic field, by the process hypothesized by Stormer many years

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earlier, might account for the Earth’s ring current. The ring current is an electric cur­rent, predominantly consisting of protons and heavier negative ions drifting westward around the Earth, which slightly perturbs the magnetic field at its location. Studies of the ring current had occupied Singer’s attention for some time, and that was the object of Laurence Cahill’s rockoon flights during the fall of 1957, as recounted in an earlier chapter.

Singer further elaborated on his ideas related to particle trapping in April 1957:

The [magnetic] storm decrease is produced by the high-velocity particles following the shock wave (up to nine hours later) which enter because of field perturbations into the normally inaccessible St0rmer regions around the dipole. Here they are trapped and will drift, producing the ring current which gives rise to the storm decrease. Particles with a small pitch angle, however, can reach the Earth’s atmosphere and contribute to aurora, the airglow, and ionospheric ionization.12

However, before the discovery of the high-intensity radiation by Explorers I and III, no one within the worldwide community of researchers, including Singer, had made the intellectual leap to suggest that a huge population of particles might be trapped there to form a durable region of intense radiation surrounding the Earth.

As in the case of the earlier Explorers, paper strip-charts were produced as a first data reduction step for Explorer IV, using the equipment setup shown earlier in Figure 11.4. But for Explorer IV, the process was a bit more complicated because of the highly classified nature of the Argus Project. For the initial month (before the first Argus detonation), during which all of the data were unclassified, data reduction was much as it had been for Explorers I and III.

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 377

However, during the month following the first nuclear burst, i. e. during the times that portions of the data showed the effects of the tests, Carl McIlwain served as a data screener. He diverted the charts containing indications of the Argus tests for special handling, where he served as the primary data reader.

Explorer IV results were disclosed in three steps: (1) an initial public release of the unclassified results, (2) an exchange of classified Argus data and results within a small circle of appropriately cleared personnel, and (3) a public release of the Argus results sometime later.

Work on the unclassified portion of the Explorer IV data was straightforward, even though rushed. The first tentative written expression of results was on 2 August 1958 in the form of a telegram from Van Allen.19 On the same date, the same information, with the addition of a block diagram of the instrument package, was recorded as a report in the Physics Department’s serial report series.20

Those two documents provided a very sketchy report based on the examination of only 15 station recordings from 26 through 29 July in the northern hemisphere and covering the altitude range from about 165 to 1000 miles. They reported that the instruments were operating properly and gave some very tentative information on the rapid increase in radiation intensity, as the satellite climbed above 250 miles height. Some first-ever information from Carl’s detector about the total energy density was also included.

Due to Van Allen’s, Mcllwain’s, and my heavy involvement in the Explorer IV effort, Ernie Ray was the only one from our laboratory to attend the Fifth General Assembly of the IGY Committee in Moscow on 30 July through 9 August 1958. While there, he received a telegram from us that conveyed a summary of the information from the two documents mentioned above. He presented that information at the conference.21

Additional releases quickly followed. On 20 August, a slightly expanded report based on a larger collection of data from the first two weeks of Explorer IV opera­tion was released.22 Among other things, it reported fluxes of both penetrating and nonpenetrating components, with the penetrating particles predominating at lower latitudes (in what came to be known as the inner radiation belt) and the nonpenetrat­ing particles predominating at the higher latitudes (at the horns of the outer radiation belt).

By late November 1958, our analysis had progressed far enough for us to issue a substantially expanded Department of Physics report.23 That paper included a number of interesting figures, one of which is reproduced here as Figure 13.3. The shape of the contours around 30 degrees north latitude provided a first hint of what was later recognized as the gap between the inner and outer radiation belts, with the cusp north of 30 degrees being the lower tail of the outer belt.

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FIGURE 13.3 A sketch from the 20 August Physics Department report showing initial results from Explorer IV. This is a meridional section through the Earth showing counting rates from the relatively unshielded GM counter. The data were taken between 26 July and 26 August 1958 within the longitude range west 60 to 100 degrees. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Libraries.)

The contours in that set of figures led to a speculative extrapolation of the radiation levels farther into space, reproduced as Figure 13.4. Actually, that particular model of the high-intensity radiation was one of two being considered when the paper was prepared. A second model, suggested and particularly advocated by Carl McIlwain, regarded the high-latitude cusps appearing consistently in the set of data plots to be the lower ends of a second distinct region of high-intensity radiation. Later observations from Pioneer 3 (described in the next chapter) showed Carl’s model to be the correct one.24 Since those Pioneer data were not available when the November 1958 report was prepared, the “simpler” of the two models, i. e., the one showing a single region of trapping, was chosen for publication.

The November report was presented at a meeting of the American Physical Society in Chicago in early 1959 and was published in March in the Journal of Geophysical Research}5 Since it had been actually mailed for publication late in 1958, well before the Pioneer 3 results were available, it still included this Figure 13.4, showing the single donut-shaped region of high-intensity radiation.

In addition to the variation in intensity with altitude and latitude provided in the first reports, the new paper provided information on the intensity variation with longitude, the angle of arrival of particles, and the nature of the radiation. In summary, the in­tensity varied with longitude in the way that one might expect from knowledge of the actual shape of the Earth’s magnetic field. Second, there was a strong dependence of radiation intensity on detector pointing angle. That was interpreted as indicating that the particles were moving predominantly in discs lying nearly perpendicular to the

lines of the magnetic field, thus helping to substantiate the model of particle trapping by spiral movement along the field lines. Third, although information on the compo­sition of the trapped radiation was very sketchy, electrons seemed to predominate at the higher latitudes, and there was a major proton component at the lower latitudes.

The last section in that paper, in both its November 1958 and March 1959 forms, was devoted to extended remarks on the interpretation of the data. It considered as well established that the “great radiation belt” around the Earth (by then the singular term belt was still being widely used) consisted of charged particles, temporarily trapped in the Earth’s magnetic field in Stormer-Treiman lunes. The paper went on to state that the overall decrease in intensity at the lower altitudes was almost certainly due to atmospheric scattering and collisional energy loss. Scattering would predominate for electrons and collisional loss for protons.

As to the injection rate, which would have to equal the loss rate in order to maintain a stable belt intensity, the paper stated that the decay of neutrons moving out from the atmosphere as a result of cosmic ray collisions with atmospheric molecules might

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help feed the belt, but that that source was inadequate by a large factor to produce the observed intensity. The paper asserted that solar plasma must replenish the reservoir of stored particles from time to time, working its way into the outer reaches of the Earth’s magnetic field under some conditions, and then being trapped in the magnetic field.

Finally, the paper suggested that the leakage of electrons from the trapping region at high latitudes might be the direct cause of the aurorae.

Earth is the cradle of humanity, but one cannot live in a cradle forever.

Konstantin Tsiolkovsky From a letter written in 1911

rom the perspective of 50 years since the event, there is little doubt that the quasi-political Soviet launch of Sputnik 1 injected the world into the Space Age as no purely scientific research program could have done. Without the U. S. national humiliation and the space race that followed, there would probably be no NASA today, no man would have set foot on the Moon, and we would not be using spacecraft as widely for research, Earth observations, and the wide array of other scientific and practical applications.

This point of view was expressed by Wernher von Braun in an April 1958 article he wrote for the Des Moines Sunday Register: “The Russian Communists may well have done themselves an ill turn by humbling us in the space race. Unwittingly, they made the sleeping American giant awaken.”1

A comment by Hugh Dryden, one of the early NASA deputy administrators, to Anatoly Blagonravov, his Soviet counterpart, at an International Astronautical Federation congress in Washington in 1961 succinctly expressed the same thought: “If we had [had] cooperation, neither of us would have a space program.”2

The new discoveries being made today with large and marvelously discriminating instruments such as those on the Hubble Space Telescope are truly remarkable. The exceedingly useful environment-observing instruments, the reconnaissance satellites, and the huge array of communications and position-locating satellites have taken us into a new world of observation, information gathering, and global connectedness.

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The instruments of the 1950s were almost laughably simple by present standards. In the first Explorer, we put a single Geiger-Muller counter and a handful of transistors and other components together to produce a data stream of only a few digital bits per second from only a few hundred miles in near-Earth space. Today, that simple circuitry could be replaced by a few square millimeters of circuitry on a silicon chip. Its information could be carried in a small fraction of the bandwidth used by today’s space probes from billions of miles away.

But keep in mind that back then, we were on the very forefront of technological progress.

The first half of the twentieth century was marked by many key Industrial Age developments that presaged the entry into space. The century was opened by the first powered flight by the Wright brothers. Only a quarter century later, the first tests of liquid fueled rockets were being conducted. Rocketry made tremendous advances during World War II, culminating in Germany’s development of the V-2 rocket. Electronics moved from the invention of the first vacuum tube by DeForest to Marconi’s first transmissions across the Atlantic to the invention of the transistor. All those advances paved the way for entry into space in 1957.

The situation today in space parallels that with respect to aviation at mid-century. We were a nearly equal distance beyond the Wright brothers’ pioneering flight then as we are today beyond the first space launch. Fifty years after the first powered aircraft flight, there were thousands of aircraft in the air on any given day. Today, the world’s space-faring nations have successfully launched more than 4000 major objects into Earth orbit and beyond.

The initial foray into space in the middle of the twentieth century profoundly and enduringly influenced our daily lives, in much the same way that aeronautics influenced the first half of the century. Space has become an integral part of our culture. We all employ space technology every day, often without thinking about it— it has become an inextricably interwoven element of telephone, Internet, television, and military communications; weather observation, forecasting, and dissemination; other environmental monitoring and appraisal; land-use surveying; global position determination; and so on.

Space terminology has even entered our everyday terse speech. In the same way that people say “bring your transistor” when referring to a transistor radio, they now say “turn on the satellite” when referring to their satellite receivers.

The opening of the Space Age had a profound effect on our physics and engineer­ing educational curricula. Sputnik aroused an immediate general sense that science and engineering training in the United States needed a shot in the arm. Higher ed­ucational standards were quickly established, and introductory texts soon appeared

Carl Edwin McIlwain was born on 26 March 1931 in Houston, Texas. He lived there during his primary and secondary school years except for the years 1942 to 1945, when his father was engaged in war work and the family lived in the states of Georgia and Kentucky.20

Showing an early aptitude for music, Carl obtained his first flute at age 10. By the time he reached high school—his family was back in Houston by that time—he was already an accomplished flutist, playing in both the school band and orchestra. During that period, he took lessons from the first flutist of the Houston Symphony Orchestra. Receiving a music scholarship at North Texas State College (now North Texas University), he spent the next four years there, obtaining his bachelor of music education degree in the spring of 1953.

During his undergraduate years at North Texas, he had an unusual experience in connection with his music training. His flute teacher, Professor George Morey, recognized a unique talent in him and served as a mentor in much the way that Van Allen did later in physics at Iowa. Carl found himself helping in teaching Morey’s students. By the time he was in his junior year, he had his own teaching studio similar to those of the teaching faculty members. He carried an active teaching load for his last two undergraduate years.

From an early age, Carl also developed a great interest and possessed a considerable natural aptitude in science. He remembers that by the time he was eight, he was often engaged with his chemistry and Erector sets. After the war, he went regularly to the army surplus stores to buy all kinds of electronic equipment for his tinkering. He took a number of high school courses in science. A physics teacher took a special interest in him and gave him the run of the laboratory, where he performed his own “play-experiments.” On one occasion, that teacher gave him an aptitude test and reported to Carl he had the highest score he had ever seen. When Carl later reported to him that he was going to North Texas to study music, the teacher expressed his surprise that he was not going into science. Carl responded, “Well,

I have a scholarship in music and none in science.” Reflecting his continuing interest in science, however, Carl also took the courses in geology, calculus, and noncalculus physics that North Texas offered.

Upon college graduation, Carl rejected several enticing high school band director’s offers and moved to Iowa City in early 1954 with his new bride, Mary, also a flutist. His initial goal was to study the physics of music. An academic position, to begin in the fall, had been arranged by his teacher and mentor in Texas, who was a former graduate of the Iowa Music Department. Carl discovered upon arrival, however, that he had been edged out of the paying teaching position by a graduating student who had decided to stay and join the Iowa faculty.21 Nevertheless, he promptly secured a chair as second flutist in the SUI orchestra, and he played with them during his first semester. However, he had to scramble to find paying work. Initially, Carl worked as a gas station attendant.

That summer, he was delighted by his employment as an hourly employee in the Physics Department’s Cosmic Ray Laboratory. One of his first tasks was to design and make a bracket to hold a large capacitor on one of the Deacon rocket circuit boards. This was his introduction to laboratory work on research instruments. It appeared to have been promising, as Van Allen gave him a research assistantship that fall.

In the academic arena, Carl signed up as a physics graduate student and enrolled in a set of undergraduate mathematics, chemistry, and physics courses to, as he put it, “get his feet on the ground.” Although his undergraduate work at Texas had not been in physics, at that time, Iowa’s only academic requirement to become a graduate student in any of its departments was to have a bachelor’s degree in any subject.

CHAPTER 2 • THE EARLY YEARS

Carl won his master’s and Ph. D. degrees in physics in June 1956 and June 1960, staying on at Iowa as an assistant professor for about a year and a half. He accepted an invitation in March 1961 to visit the campus of the University of California at San Diego, located at La Jolla, California. He and Mary were immediately taken by the research opportunities, location, and climate. They moved there, with Carl as a tenured associate professor, in February 1962. Appointed as a full professor in 1966, he continued his work there for the rest of his professional career. In addition to conducting a highly productive space research program, he served over the years in a number of important national advisory capacities.

Carl agreed to take on the development of the Loki rockoon for his master’s thesis. He later admitted that he had no appreciation whatever of the challenge that was presented by breaking into the space instrumentation business with no more electron­ics experience than he possessed.22 I still marvel that Carl was able to become so outstandingly effective in this work in such a short time.

The instrument that Carl developed used a single GM counter to continue the high-latitude survey that had been the original goal of the Iowa rockoon program, that is, to learn more about the energy spectrum of the primary cosmic radiation by measuring its geomagnetic latitude dependence. The very high acceleration of the Loki rocket (270 times the Earth’s gravity [g], compared with 60 g for the Deacon rocket) presented a special design problem. Carl tested individual components to 1000 g in a centrifuge and conducted static load tests on an assembled payload to make sure that they would withstand the launching forces. The final instrument, of which several are seen in Figure 2.9, was a marvel of miniaturization, weighing only 6.8 pounds. He completed the design work and built a complement of 10 instrument payloads in time for the 1955 expedition. That was accomplished at very low cost— the funding provided by the National Science Foundation for designing and building the instruments and procuring the flight hardware was only $2000!23

The third goal of the 1955 expedition was to see if the basic rockoon technique could be extended to reach higher altitudes. Van Allen had envisioned a balloon – launched, two-stage Deacon-Loki rocket combination that might carry the instruments to great altitudes, perhaps as high as 180 miles. To test this concept, Carl Mcllwain mated a Loki I rocket (with his GM counter package) to the top of a Deacon rocket by means of a specially designed adapter. The whole assembly was to be carried to firing altitude by a much larger Skyhook balloon. Two such assemblies were prepared to test the concept, and to attempt to obtain the first ultra-high-altitude data.

The summer of 1955 was a hectic period, as we all worked in a near-frenzy to complete the flight hardware and supporting ground equipment. In addition to McDonald, Carl, and me, the overall construction and testing effort included a heavy workload in the

instrument shop and the capable and energetic help of very talented and dedicated student assistants and aides. Although Carl had his instruments in essentially complete form by the time they had to be shipped, Frank and I were further behind. We had to complete some of our final detector mounting, checkout, and calibrations later aboard the ship.

The field team consisted of Frank, Carl, Joe Kasper, and me. Frank served as the team leader, and Joe went as a general assistant, providing his invaluable help to the rest of us throughout the expedition.

That field expedition was a tremendously exciting and broadening experience and a highlight of my undergraduate years, but it did represent my first extended separation from my family since leaving the Air Force. Daughter Barbara was three, Sharon had just passed her second birthday, and Ros and I had just passed our fifth wedding anniversary.

I felt the strong desire to share this new experience with her. As no letters could be sent from the ship, I kept a fairly detailed diary, which I presented to her upon my return. That diary provided substantial information for this account. In addition to it and my other records, I drew upon published accounts by Carl McIlwain and Frank

CHAPTER 2 • THE EARLY YEARS 43

McDonald.24,25 Carl also kindly made his personal slides available, and Meredith’s unpublished notes provided further details.26

Joe and I, serving as an advance party, left from the Iowa City airport on a United Airlines DC-4 early on Tuesday, 13 September. Although I had accumulated many hours as a pilot in the Air Force, this was my first flight on a commercial airliner. That was in the more relaxed days before aircraft hijackings and terrorist attacks, and I was able to go into the cockpit to watch the pilots at their work. We had a few hours layover at Washington, D. C., and Joe and I hired a cab for a drive-by tour of many of the standard tourist attractions. We arrived at Norfolk, Virginia, late that afternoon and stayed overnight in a downtown hotel. The next morning, Joe called the port director for our ship’s location, and we went aboard.

It was the USS Ashland, a Landing Ship, Dock (LSD), with a 500 foot long open hold.27 The rear of its hold was closed by an immense watertight door that could be lowered to form a ramp. The whole ship could be lowered in the water by flooding the hold and ballast tanks. Smaller boats could then move into the hold, the gate could be closed, and the water in the hold and the ballast could be pumped out so that the ship with its load of boats could rise from its lowered position. The ship could then steam at normal speed while the captive craft could be serviced, outfitted, and loaded as needed. The mother ship was fitted with extensive machine shops, cranes, and other facilities for that purpose. Another wartime role for the LSDs was for amphibious landings, where flotillas of Landing Crafts, Assault (LCAs), Landing Ships, Tank (LSTs), and other craft could be carried in their flooded holds and disgorged at a beach. Thirty-one of these LSDs were built during World War II (WWII).

Ours, LSD-1, was the first one built, and the last one to remain in active service. It was powered by reciprocating steam engines rather than by the turbines that drove later models. A flat superstructure about 70 feet wide by 150 feet long, erected over the rear of the open hold to serve as a helicopter landing deck, served as our work platform for inflating and launching the rockoons. Although fully operational, old LSD-1 looked shopworn—I irreverently (and privately) rechristened it the USS Ashcan. Its primary mission on this trip was to carry supplies to Thule AFB in northern Greenland—our scientific expedition was accommodated as a secondary task.

As was customary for scientific expeditions aboard Navy ships, civilian scientists were accorded officer privileges and lived in officer’s quarters. Since Joe and I were the first of the scientists aboard, we had our pick of the available staterooms. We chose one on the bridge deck next to the officer’s wardroom. Our passageway led to the bridge, which served as a great vantage point for watching shipboard activities. I enjoyed those pleasures for only a short time, until the rest of the equipment and team arrived. As soon as that happened, I was completely absorbed during every waking

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hour with helping to set up our laboratory, completing our instruments, and launching the rockoons.

During that initial slack period, Joe and I struck up a close friendship with Navy Commander Augustus (Gus) A. Ebel and Commander Bracken. Gus, a Ph. D. physicist assigned to the ONR, took care of all liaison matters between the scientific teams and the Navy, both on ship and on shore. Mr. Bracken was the ship’s executive officer. During the next several evenings, the two of them led us on evening shore excursions where we discovered the mysteries of nearby streets that boasted countless bars, arcades, and brothels, whose primary purpose was to relieve sailors of as much of their money as possible during their shore leaves.

Our equipment arrived and was hoisted aboard on Thursday. The batteries for our instruments were appropriately stowed in the battery-charging room, and the rockets were placed in the ammunition magazine. Joe and I took over a large room belowdecks to serve as a shipboard laboratory, and we began setting up our equipment. We also began searching for a suitable additional room to serve as a darkroom for developing the film from our ground data recorder.

Ed Lewis and Herbert Ballman from Winzen Research, along with a General Mills observer, arrived that day. Winzen Research, with Lewis in charge, conducted that expedition’s balloon operations.

Frank and Carl also arrived late that Thursday night. The next morning Carl discovered, to his great dismay, that some of the Loki rockets had been shipped with one inch stub fins suitable only for low-altitude launches. He had asked when ordering them that they be fitted with larger fins to assure stability during the high-altitude launches, but that request had been ignored. Frank and Carl made an emergency trip to a Norfolk hardware store for sheet aluminum, returned, cut appropriately sized fins, and screwed them onto the rocket’s stub fins. They worked!

Two NRL rockoon-launching groups also accompanied this expedition. Les Mered­ith by that time had joined NRL and set up his own research program there. His instru­ments were also designed to further study the auroral soft radiation. Accompanying Les were Leonard (Leo) R. Davis and Howard M. Caulk. The NRL also fielded an optics group led by James (Jim) E. Kupperian Jr. and accompanied by Robert (Bob) W. Kreplin. The trailer that supported both NRL groups arrived on Friday and was hoisted aboard and firmly anchored on a corner of the flight deck. I marveled at the ease with which their trailer-based laboratory was put in operation—as soon as it was connected to electrical power, they were in business. Because of the simplicity of that process, the NRL groups were able to relax and enjoy pleasant hours with the ship’s crew for several days, while Frank and I labored to set up our laboratory belowdecks.

The helium also arrived on Friday—I was impressed by the large number of helium bottles required. At that time, virtually all the helium in the United States was being

produced at a single plant in Texas. I was told that our balloon expeditions used a substantial portion of the then-current worldwide production capacity. The bottles were stowed in the ship’s massive hull, as depicted in Figure 2.10.

That evening, we were invited to the Captain’s presailing cocktail party. This was our first opportunity to talk at length with Captain Bryce, who was wonderfully accommodating and helpful throughout the entire expedition.

Frank and I ran into our first serious problem on Saturday as we were trying to get our ground station in operation. The ship’s primary electrical power was direct current—there was very limited alternating current (AC) power. Of course, all of our laboratory equipment required AC. Although an AC power receptacle had been found on deck for the NRL trailer, there was none in or near our laboratory. Our extension cords were not heavy enough to carry the load from any available source. Joe and I made an emergency trip to a Norfolk hardware store to buy enough AWG #8 residential service cable to make a super extension cable. The crew installed it for us—for an easily negotiated price of six rolls of Scotch-brand electrical tape. We were able to complete the installation of the laboratory equipment and receiving station on that day and immediately started on the final assembly and calibration of our instruments.

At that point, we had another major interruption—Hurricane Ione was heading straight for us. On Saturday evening, our ship, along with more than 80 other Navy ships, put out for hurricane anchorage in the middle of the Chesapeake Bay. As the ship

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steered with its head into the wind throughout the blow, there was surprisingly little rolling or pitching. This interlude gave Frank, Carl, and me more time to continue the work on our instruments. We rode out the storm’s near-approach for the next several days, returning to the Norfolk area on Tuesday. The hurricane turned out to be a relatively mild one, and no significant damage was done to ships or other Navy facilities.

By Wednesday, 21 September, the water was calm, the sky was clear and blue, and the crew was able to complete the ship’s loading and fueling. We made way for the ocean that afternoon. By then, Frank and I had completed work on 4 of our 10 instrument packages. Once we reached the open ocean and began experiencing a 10 degree roll with some pitching, we began to appreciate the difficulties in working in the ship’s cramped and wildly gyrating quarters. The demanding precision work became remarkably inefficient. Nevertheless, we made reasonable progress.

Thursday night, we paused to rendezvous with a coast guard cutter near Woods Hole, Cape Cod. One of the ship’s radar men had had an acute attack of appendicitis. He was very fortunate that it happened there rather than later, as there was no doctor aboard.

On Friday, 23 September, at about 4:00 PM, off the lower tip of Nova Scotia, we sent off the first rockoon, one of Carl Mcllwain’s Lokis. It was a success in every way—the first time that the initial shot on one of these expeditions had worked properly. I manned our receiving antenna located on the roof of the NRL trailer during the ascent and reported my sighting of the visible trail when the rocket fired. We determined later that it had fired at 72,000 feet and climbed to about 230,000 feet altitude. Although the signal was lost for a moment at the time of ignition, Carl soon retuned the receiver to a slightly shifted frequency. Once acquired, the signal remained strong throughout the rest of the flight. Carl was elated by his early success. Of course, this far south, the auroral soft radiation was not seen, nor expected.

By that time, Frank and I had six of our Deacon instruments completely checked and ready to go. The next day, Saturday, we launched the first of them. Figure 2.11 shows the balloon preparation for a typical launch. My diary entry for that event provides a summary of the process, and clearly reflects the elation of a proud young university student experiencing his first successful field launch:

Success! The exuberance of first success! Today we fired a Deacon. We got a very good cosmic ray record. The auroral effect was not found, but we didn’t expect it this far south. The main thing is that the equipment has been proven OK. It’s a wonderful feeling when something you’ve lived with closely for so many months works as planned. I’ve done more working, planning, sweating, and worrying about this project than any I’ve tried before. But when the sound of the subcarrier oscillators, modulated as they should be, comes over the receiver, and the Brush recorder keeps on writing down the data, it is all worth it.

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When I went to bed last night, the plans were laid. We were scheduled to fire at 10:00 this morning. So, for a change, this morning I was up bright and early at 6:45 for breakfast. Breakfast consisted of scrambled eggs, sausage, toast, and three cups of coffee. The com­panionship of the other scientists (that is what they call us aboard ship) is very pleasant and gratifying. It is great to sit around the table and sip coffee while talking over problems and plans.

After breakfast, Frank and I went down to our recording station. We started putting the rocket head that we intended to use through its final paces. There is the checking of counting rates, the calibration of the system for recording pulse heights, the checking of battery voltages as the instrument operates on its own power, the readying of the recording equipment, and finally, the cone is slipped over the equipment and tightened by its 18 screws. The cone is now sealed and operating, not to be opened again.

Meanwhile, the people on the launching deck have been working. Joe [Kasper] and Mr. [.sic: Commander] Ebel have been putting the fins on the rocket, arming it, attaching the firing box, and placing the bag over the rocket. The Winzen Research people have been inflating the 75 foot diameter balloon in preparation for the launch.

After the head [instrumented payload] was sealed, Frank carried it up and they attached it to the rocket. I remained at the recording station to keep a check on it. I noticed noise on the channels at times, and variations of signal strength. I tried to have someone up on the deck check on it (we have telephone communication between recording station, van, and antenna) but there I learned one lesson. When a launching goes that far, it is almost impossible to interrupt it. The balloon is already partly inflated and the only way to abort or delay a launching is simply to cut the balloon loose and start over from scratch. Since the equipment was working a little we decided to go ahead.

Finally came the word—cut loose—the rocket was on its own. Then began the scramble to find out what was causing the trouble. (Our setup used the antenna, preamplifier, and receiver on the NRL trailer on deck, with a line passing the signal from the trailer to the remaining equipment in our laboratory belowdecks.) First of all, they discovered that something was

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wrong with the preamplifier. That still did not cure the trouble, but soon we decided that the trouble was not in the rocket, but rather with the NRL equipment in the trailer. We had our own receiver standing by down in our recording station, so we bypassed all NRL equipment, going directly from antenna down to our receiver. Success! There was still a loose connection somewhere, causing occasional interference, but not serious. It didn’t foul up more than a few seconds of data.

The balloon ascent took about an hour and a half. Finally, at about 70,000 feet, the Racon quit, our frequency shifted slightly, and the rocket was off. The rocket flight lasted four and one-half minutes, during which time there was a constant scurry, to check everything (the recording of the signal), check time on the chronograph, etc., etc.

Finally, the signal faded out quickly, there was nothing but noise on the Brush recorders, and the flight was over. The rocket, its nose assembly containing months of labor, and all that beautiful electronic equipment, was deep in the sea. But we have 200 feet of paper and 100 feet of film that testify to the fact that it was well spent.

The signal strength remained above 100 microvolts during the balloon ascent and above 5 microvolts during the rocket flight, except when they were aiming the antenna. Since we had made such a quick changeover on the receivers, the meter for directing the person aiming the antenna could not be connected, and orders had to be given orally. This doesn’t work too well, so we have that fixed now. We installed a line to operate the meter.

We had been somewhat concerned about the subcarrier frequencies. Before leaving home, I discovered a strong dependence of frequency on filament voltage. But all during the flight, until rocket firing, they held steady. After firing, I was too busy worrying about other things to look, but I’m sure they are OK. At least the information came over them and that is the final criterion.28

That same day we got off another of Carl’s Lokis—also a success. Sunday we passed over the Grand Banks east of Newfoundland. In the relatively shallow water, the seas were still showing the effects of Hurricane Ione that had preceded us up the coast. The USS Ashland was, to say the least, not well suited for rough weather. With its broad bottom, it took up a wild rolling and pitching motion. At times, the ship would seem to remain poised on one of its sides for a few moments, and then over we would go with a sickening whop to the other side. Throughout the night, we heard lockers and other gear crashing and banging in the passageways. Most of the scientists and many of the crew were seasick, but fortunately, I escaped that indignity. By wedging myself between the front rail and rear of my bunk, I was even able to get a reasonable night’s rest. Figure 2.12 shows a sample of the tricky inflation exercise near the Grand Banks.

Soon after passing to the north of Newfoundland, the swells abated, the weather began to turn colder, and I broke out my parka. Rockoon launching soon settled into a busy but purposeful routine as we proceeded farther north. Since Carl’s scientific objective was a comprehensive latitude survey of the primary cosmic rays, he spread his flights out en route through the Davis Strait between 43 degrees and 73 degrees north geographic latitude (about 54 degrees to 84 degrees north geomagnetic latitude). In contrast, the primary objective of the Deacon flights (except for the early shakedown launch) was to study the auroral soft radiation. We launched the rest of our instruments

between 57 degrees and 68 degrees north geographic latitude (68 degrees to 79 degrees north geomagnetic latitude).

The second Deacon rockoon was launched on Tuesday afternoon, 27 September, at a geomagnetic latitude of about 69 degrees. Everything worked well, and we saw a large flux of auroral soft radiation—the counting rate was about seven times the rate that it would have been without the auroral radiation. Three other attempts were made by other groups that day, but unfortunately, they all failed. On one by Les Meredith’s NRL group, the rocket fired, but the flight data turned out to be unusable. In the attempt by Kupperian’s NRL group, the rocket failed to fire. During Carl’s next Loki attempt, his GM counter went into continuous discharge, so that he received no useful data.

The elaborate traditional initiation into Ye Royal Order of the Blue Nose for our first crossing of the Arctic Circle was also held on that day. Since it took place when Frank, Gus Ebel, and I were busily preparing for our launch, we were excused from that boisterous and disgustingly messy rite of passage. I was delighted that we received our certificates anyway!

The pace of our operations peaked during the next two days, with three more flights by Frank and me (all three successful), one each by the two NRL groups (both failures), and the flights of both of our two-stage rockoons (also failures). The auroral effect was seen again in Frank’s and my second and third flights, a 2.5 times normal effect at about 72 degrees geomagnetic latitude and a 2 times effect at 76 degrees. On the fourth flight at about 78 degrees north geomagnetic latitude, we saw no excess radiation and surmised that we were too far north to observe it. We decided to hold

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the remaining five Deacons for the return trip and concentrated on completing the final preparation of the remaining instruments during the rest of the northbound trip.

The prospect for reaching an unprecedented high altitude with small two-stage rockets was an exciting one.29 The field operation, however, was risky. Frank, Carl, and I still shudder when we think about it, especially in the light of the later accidental misfiring of a Loki rocket on the ship’s deck. We had limited means for assembling the tall two-stage configuration on the ship, as its combined height was more than 17 feet. As seen in Figure 2.13, we used the NRL trailer and a stepladder as our “gantry,” first setting the Deacon rocket (with its igniter in place but not connected) vertically on the deck, then carefully mating the Loki rocket (also with its igniter installed) atop the Deacon-Loki adapter.

CHAPTER 2 • THE EARLY YEARS 51

Then came the perilous task of moving the nearly 200 pound assembly across about 75 feet of deck to position it directly under the, by then, inflated and tethered balloon. Since we had no suitable wheeled conveyance, several of us encircled the Deacon rocket with our arms and, with the Loki teetering above, manhandled the assembly across the deck.

Once under the balloon, the Loki’s firing lanyard was attached to the top of the Deacon. Its function was to ignite the Loki once the Deacon had completed its burn and differential atmospheric drag had separated the two rockets. For safety’s sake, barometric pressure and acceleration-activated switches were included to prevent the Loki from firing until it reached altitude, and until after the Deacon had fired. The Deacon firing box was tied by its cord to the bottom of the Deacon’s tail fins and connected to the igniter.

At that point, the balloon’s tether was reeled out so that it could take up the slack on the load line, and then the whole assembly was released. The balloon carried the multistage rocket to its launch altitude.

In the first attempt, the Deacon rocket fired, but there was no second-stage ignition. Carl surmised that he had made the fit of the adapter between the top of the Deacon and the Loki rocket nozzle too tight, so that the two stages did not drift apart. With a file, he reduced the diameter of the coupling for the second attempt. On that attempt, the balloon ascended and both the Deacon firing and Loki ignition were normal. The GM counter operated properly initially, but two and a half seconds after Loki ignition, the transmitted signal was strongly modulated by noise for about a second, and then ceased altogether.

After Carl returned home, he mentioned this attempt to one of the engineers at the Jet Propulsion Laboratory, who responded, “Why didn’t you tell us what you were going to do? We would have told you that the thin aluminum nose cone would melt.” After some confirmatory calculations, Carl and Van realized that they had grossly underestimated the aerodynamic heating of the Loki’s aluminum nose cone at its initial flight velocity of greater than 5000 miles per hour, and the nose cone and instruments probably did melt.

Van Allen stated later, “It is probable that an inexpensive two-stage rockoon can be made to carry small payloads (~7 lb.) to summit altitudes of over 1,000,000 ft. [about 190 miles] if temperature-resistant materials (e. g. stainless steel) are used for the nose cone and the tail fins of the second stage.”30 Van Allen also stated, “Retrospectively, it appears likely that this inexpensive technique, given a heat – resistant nose cone, would have resulted in discovery of the geomagnetically trapped radiation.”31

No further attempts were ever made with that configuration. The Van Allen Ra­diation Belt discovery had to wait for two and a half more years for the flight of the Explorer I and III satellites.

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The voyage continued. After passing a steady parade of icebergs for several days, we reached Thule on the northwest coast of Greenland on Saturday morning, the first day of October. We were presented with a frigid and barren-looking scene, with not a tree in sight. This sizable military outpost was spread out on gently sloping land between the indentation of the bay and background hills to the south. The dominant color was brown, with a few snow banks still showing on the northern slopes of the hills. Being just past fall equinox, the Sun crept low across the southern horizon during the day and just beyond the northern horizon during the lengthening night.

Even today, whenever I look at a globe, I am impressed anew by how far north Thule lies. It is above 76 degrees north geographic latitude—about 400 miles more northerly than Point Barrow and Barter Island on the northern coast of Alaska, and only a little more than 1600 miles below the North Pole.

Since Frank and I had completed the preparation of our remaining Deacon in­struments by that time, and there was a large enough crew without me to handle the rest of the launches, I left the expedition at Thule for Iowa City to return to the classes that would complete my undergraduate studies. Les Meredith also needed to return for a White Sands rocket launch. We hitched a ride on an Air Force C-54 and made an uneventful trip stateside. Arriving back in Iowa City on Tuesday, 4 October, I was over two weeks late in starting my fall classes (advanced calculus, differen­tial equations, modern physics, and electricity and magnetism). I struggled mightily throughout the rest of the semester to try to catch up but was never able to do so to my satisfaction.

On the ship, Carl still had three of his Loki rockets to launch, and Frank had five more of our Deacons. The ship’s first order of business, however, was to make a side trip to Pond Inlet on the north end of Baffin Island to pick up a Catholic priest. Frank, Carl, and Joe were told that he had “lost his mind over the local custom of slipping unwanted girl babies under the ice.”

Shortly out of Pond Inlet, on 4 October, Carl made another successful Loki launch. Two days later, Frank successfully launched another Deacon rockoon. After several days’ stop at Frobisher Bay to drop off supplies, Frank continued with the launching of the remaining four of our Deacon rockoons as the ship progressed again through the auroral zone. Two of those were successful and provided good data on the auroral soft radiation, but two rockets failed to ignite.

Carl’s next attempt resulted in a highly disturbing and potentially tragic incident, the unexpected ignition of a Loki rocket on the ship’s deck. By Frank McDonald’s account:

A Loki rocket ignited in its horizontal cradle as the ONR representative, G. Ebel, was adjusting the backup timers in the control box that was suspended below the rocket. The rocket struck a stack of helium tanks and exploded, covering the deck with smoke and debris.

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Ebel’s face was badly burned. The ship had a medical corpsman but no doctor so we headed for the nearest port. Ebel had a rapid and complete recovery. I returned via Washington to receive the full wrath of ONR for what had already been a traumatic and unsettling event. In a test at Iowa, C. McIlwain found that the length of the wires connecting the rocket [igniter] to the control box was such as to probably produce standing waves, and trigger the igniter.32

Carl added further details. His tests upon returning to Iowa showed that the trans­mitter in his instrument package probably induced a current in excess of 0.2 amperes in the igniter wires, and that was enough to set off the rocket. Parenthetically, he mentioned that this had been his “best” transmitter, having been tuned to produce the greatest output power of all of his instruments.33

The less than one second normal burning of the rocket was essentially a controlled explosion. The blast centered on Gus Ebel’s shoulder, where it burned through his thick clothing and embedded bits of igniter wire in his flesh. Joe Kasper was standing nearby, and his eardrums were ruptured, his coat was blown off, and bits of propellant were embedded in his lips and face. Carl was about six feet to one side and suffered only mild noise trauma. As the rocket accelerated, its sharp fins sliced through the three-quarter inch thick plywood brackets that formed its supporting cradle, then snipped the phone wire draped from the headset of the sailor who was serving as the talker in contact with the bridge. He took an instinctive giant leap backward and landed, luckily, in a gun turret adjacent to the flight deck rather than in the icy sea. By the time the rocket had traveled about 50 feet and struck the stack of empty helium cylinders, it had already reached supersonic speed. Upon impact, the rocket exploded, spreading parts of the rocket, flight instrument, and burning propellant over the entire ship.

Captain Bryce immediately ordered that the remaining Loki rocket be dumped overboard, but Carl saved his remaining highly prized instrumented payload. The scientific work was terminated, and the ship proceeded as quickly as possible to St. Johns, Newfoundland, to get medical attention for Gus Ebel. The ship returned to port at Norfolk in mid-October without further incident.

Carl’s tenth rocket instrument was put to good use later. On the morning of 23 February 1956, a breathless call from John Simpson at the University of Chicago stated that a gigantic solar storm was bombarding the Earth with cosmic rays. Carl hurriedly attached his unused payload to a cluster of rubber balloons and launched it from the university’s athletic field, and it reached peak altitude about 17 hours after the onset of the storm. Too late for the main event, the rig found that solar cosmic rays were still adding about 40 percent to the expected galactic cosmic ray counting rate. That event served as the subject for Carl’s first published paper.34

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I was elated by the expedition’s success. Frank’s and my instruments operated perfectly on all 10 flights. Eight of the 10 flights reached their expected altitude and provided useful data. Carl’s success rate was excellent for the first field trial of a new rocket, with four successes out of the six single-stage attempts. Those flights provided the basis for Carl’s master’s thesis.35 The NRL flights were more disappointing. Both of Jim Kupperian’s attempts failed, and Les Meredith was successful with only two of his six attempts.

This record solidly established the Loki rocket as a viable carrier for rockoon launches. After honorable service during four shipboard expeditions, the Deacon rocket was retired as a rockoon component at the end of the 1955 campaign. An improved version of the Loki rocket (Loki Phase II) was used exclusively on the later Iowa rockoon expeditions.

The end of 1956 and beginning of 1957 saw a major change in emphasis. The focus changed to the merging of subassemblies to form a complete prototype package.

138

Robert Baumann had given me the first full set of dimensioned drawings of the satellite shell. It included details of the envelope for our instrument package and of the structure for supporting and thermally insulating it. With that information, I drew a diagram of the physical arrangement of our instrument package, as reproduced in Figure 5.3.18 That notebook sketch was followed by a detailed weight breakdown that totaled 13.3 pounds (including the telemetering system and its batteries).

Thus, by the end of 1956, all of the key satellite and instrument features and parameters had been established.

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 139

The Vanguard instrument testing program The satellite had to operate in a pre­viously unencountered physical environment. The effects of a completely isolated thermal environment for an extended period were unknown. It was expected that the satellites would be subject to small dust particles traveling at great speed, but their numbers and sizes were unknown, so that their effect on the satellite could not be predicted. The satellite and its internal instruments would have to survive the extreme vibration and acceleration of the rocket launches.

The attempt was made to design the satellite to operate over as wide a range of the environmental parameters as possible to span the range of uncertainties. An elaborate testing program was devised to verify the design, as well as to weed out any incipient component failures. Homer Newell had informed us as early as November 1955 that the expected conditions for the satellite instruments included operation over a temperature range of at least 41 degrees to 122 degrees Fahrenheit (5 degrees to 50 degrees centigrade). He also indicated that the instruments would have to survive spin rates of250 to 400 revolutions per minute and very high initial linear acceleration values.19

The testing program continued to evolve. On 7 May 1956, a more complete set of conditions was promulgated:20

• Operation in a complete vacuum

• Operation after a temperature cycle lasting 90 minutes from values of -28 degrees to +104 degrees Fahrenheit (-30 degrees to +40 degrees centi­grade)

• Survival of sinusoidal vibration at levels of 8g (eight times the Earth’s gravity), varying in frequency from 20 to 2000 cycles per second, with tests lasting for 10 minutes in each of three mutually perpendicular directions

• Survival of random vibration (similar to acoustic “white noise”) at levels of 20 g RMS, with a uniform spectral density in the range 20 to 2000 cycles per second, with tests lasting for five minutes in each of the three mutually perpendicular directions

• Survival after a steady acceleration of 50g for 15 minutes along the primary axis

Final test specifications were issued at the December 1956 meeting.21 There were to be two series of tests. The first series, of design level tests, was to help assure that the instruments could survive the launch phase and then operate over an extended period in space. Those levels were set somewhat higher than the levels actually expected to occur, to provide some extra margin in the design. As those tests might overstress the hardware and components, the design test hardware would not be flown.

The second set of tests, referred to as flight acceptance tests, were to be applied to all flight payloads. They were carefully set at levels that would not unduly stress

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the instruments but that would help detect deficiencies in assembly and incipient weaknesses of electronics components and mechanical assemblies.

Responsibilities for conducting the tests were also established at that meeting. In Iowa City, we were to run design-level vacuum and temperature tests on our subassem­blies and the complete prototype instrument package, and design-level vibration tests to the limits of our capabilities at Iowa. As it turned out, all vibration tests were performed at NRL, since we were unable to obtain the necessary test equipment at Iowa in time for the tests.

The NRL was responsible for design-level vibration tests of a prototype data recorder in late January 1957 and of a complete Iowa prototype package in mid­May. They would also perform the vibration and acceleration tests for the complete satellite. And they would be responsible for the entire gamut of acceptance tests (vacuum, temperature, temperature cycling, vibration, and acceleration) for the flight hardware. Those were scheduled to begin on 15 June.

February 1957 As we entered 1957, I completed the assembly and initial temper­ature testing of the first flight-realistic electronics deck, a binary scale of 128. That test item is pictured in Figure 5.4. Other major work included GM counter measure­ments, tape recorder tests, preliminary design of a 700 volt power supply for the GM counter, design and testing of the tuning fork time standard, and assembly of the second electronics deck.

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We were especially concerned about the ability of the GM counter and tape recorder to withstand the expected vibration and acceleration levels. Special tests of those components were conducted in the NRL vibration test facilities on 18 February.

I referred to the package that I assembled for that test as prototype unit 1, or simply PT1. Although some of its circuit boards and battery modules were dummies, the GM counter and tape recorder, along with minimal circuits and batteries to operate them, were mounted in a realistic manner. The packages assembled later for the June, August, and October tests were referred to in my working documents, respectively, as PT2, PT3, and PT4.

Robert Baumann, several of his technicians, and I installed PT1 in one of the early NRL-designed satellite shells. In addition to testing our package, the vibration test was intended to test a number of mechanical features of the shell, as well as an array of solar cells that the NRL engineers were considering for use on later satellites.

With fingers crossed, we began the tests. They consisted of three sets of runs, one along the instrument’s vertical axis, that is, along the launch rocket’s primary thrust axis, and others along two mutually perpendicular horizontal axes. A series of four tests covering different frequency ranges and with increasing vibration amplitudes was to be completed for each of those orientations.

The first set of runs along the vertical axis was completed without incident. Runs along the first horizontal axis were also satisfactorily completed. But the test series along the second horizontal axis, with sinusoidal vibration sweeping over the fre­quency range 2000 to 16 cycles per second, resulted in a number of failures. Specif­ically, (1) two antenna rods broke off, (2) the satellite shell cracked at its bottom because several screws had loosened, (3) the bottom broke out of the NRL-supplied instrument container, (4) two Kel-F thermal insulators broke, and (5) the satellite internal support tubing broke in two places. There is little doubt that one or some of those failures caused others, but there was no way to determine which one occurred first and precipitated the chain of events.

Happily for me, my instruments survived the tests with no failures—there was no damage to either the GM counter or tape recorder. [1]

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great confidence in their work and led, eventually, to the collaborative arrangement whereby they designed the high-voltage power supplies for the GM counters and supplied component parts kits that we assembled in the early Explorers.

Returning from Fort Monmouth, I stopped for a visit with Gerhardt Groetzinger at the Glenn L. Martin Company’s Research Institute for Advanced Studies (RIAS) in Baltimore, Maryland. He was developing a cosmic ray ion chamber that he hoped to fly in the Vanguard program but that eventually flew on Explorer 7. Needing long-term data storage, he was interested in my tape recorder, and I showed him my plans, a sample recorder, and a sample scaler deck. Eventually, I supplied him with complete tape recorder fabrication plans and a sample unit, and he incorporated it into his instrument design, as described in Chapter 14.

In early March, Ed Manring from the Air Force Cambridge Research Center visited us in Iowa City, and we began detailed planning for integrating their micrometeorite instrument into our package. That marked the beginning of a very enjoyable working relationship that resulted in the inclusion of their instrument in the Vanguard payload and on the later Explorers I, II, and III.

April 1957 All Vanguard satellite designers met again at NRL on 24 through 27 April 1957 (Figure 5.5).23 That gathering began with brief status reports by Bob Baumann (satellite structure), Roger Easton (Minitrack), Whitney Mathews (teleme­try), Jim Heppner (magnetometer experiment), Herman LaGow (environmental ex­periments), Herbert Friedman (Lyman-alpha experiment), the author (cosmic ray experiment), Ed Manring (micrometeorite experiment), Vern Suomi (radiation bal­ance experiment), Bill Stroud (cloud cover experiment), and Warren W. Berning (resonant reflecting dipole experiment). Working sessions with the experimenters and individual NRL engineers occupied the next several days.

The working sessions were followed by a meeting of Van Allen’s Working Group on Internal Instrumentation. At that meeting, held in the old “temporary” Navy building T-3 on the west end of the Washington Mall, each experiment group gave a status report reflecting their progress.

My SUI report contained a final block diagram of the instrument, a description of its operation, and a summary of our status. It also included a drawing of the arrangement of our instrument in the satellite shell, reproduced here as Figure 5.6. I showed models of our instrument mockup and the tape recorder, and reported in detail on our power and weight requirements. My report concluded with the statement, “SUI expects to be able to deliver the first instrument package, complete in every respect and operating, to NRL for vibration testing on 15 June 1957. We further expect to deliver three flight units to NRL on 1 August 1957 which are to be given acceptance tests by NRL during the six months period following that date.”24

My notebook entry on 3 May 1957 indicates that I was, by then, providing detailed information about our cosmic ray instrument to Ernst Stuhlinger at the Army Ballistic Missile Agency in Huntsville, Alabama.25 That was to permit their group to move forward with the off-the-record development of a scientifically useful satellite for the Jupiter C launch vehicle. That preliminary work laid the foundation for the shift of our instrument from Vanguard to the Jupiter C launch vehicle following the Sputnik 1 launch, as related in Chapters 7 and 8.

June 1957 We were tremendously excited on 6 May, when the first aluminum prototype satellite shell arrived.26 Wayne Graves and I immediately tried fitting our evolving prototype instrument package into the satellite, as shown in Figure 5.7. To our considerable relief and elation, it fit perfectly!

PACKAGE

SEPARATION DEVICE

FIGURE 5.6 Drawing of the Vanguard cosmic ray satellite as of April 1957. The central cylin­der with the stack of decks is the instrument package that we were assembling at Iowa. The shell, antennas, and internal structure were developed and produced by NRL.

We were working toward an all-up vibration test on 15 June. The test was actually conducted on 27 May. As that date approached, Wayne Graves, Riley Newman, our other student helpers, and I worked feverishly into the late evenings to ensure that the tests would be as comprehensive as possible. It became clear, however, that the instrument package would still be incomplete. Nevertheless, I still hoped to prove the physical design of the overall package and the operational viability of a major portion of the electronics. One of the most pressing specific objectives was to make a full and meaningful test of the tape recorder, including its control, recording, and playback capabilities.

Arriving in Washington, D. C., on Sunday, 23 June, hand carrying my instrument package in its wooden carrying case, my ever-present toolbox, and a kit of supplies, I began the next morning with some of the final preparations of our prototype (PT2) on a bench in the NRL facilities.

By Wednesday evening, with the vibration test set for the following morning, I still had to complete the master interconnecting wiring harness and to verify that the fully assembled package was operating properly. In my hotel room, at its small writing

desk, with my soldering iron plugged into a nearby convenience outlet, and with the test equipment, hand tools, kit of wire, and other supplies that I had carried from Iowa, I worked on that final wiring late into the night. At about 2:00 on Thursday morning, it was done. The package as it existed at that time included the fully operational transmitter, modulator, subcarrier oscillator, calibration system, binary counters, and battery stacks. The receiver was included but not working, apparently due to a transmitter interference problem that would have to be worked out with the NRL engineers. Provisional tuning fork timing and recorder stepping circuitry would also be replaced by improved designs.

After a few hours’ sleep, I drove to NRL in south D. C. on the morning of 27 June to help in setting up for the vibration tests. The NRL teams had also been working hard—by the time I arrived, they had completed the assembly of the satellite shell, the interior instrument support structure, and the jigs for physically mounting the satellite on the vibration table. We inserted my instrument package into the shell, connected

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the radio frequency harness to the antennas, activated the instrument, verified its operation, closed the access port, and mounted the fully assembled package on the vibration table.

Four series of design-level verification tests were planned at progressively higher vibrational levels.27 Each series consisted of three runs, first with vibration along the thrust axis (vertical), second with vibration perpendicular to the thrust axis (horizon­tal), and third, also with vibration perpendicular to the thrust axis, but 90 degrees from the previous tests. All runs were to be of four minutes’ duration, with vibrational ac­celeration within the frequency band 10 to 2000 cycles per second. The levels were to be at 15,20,25, and 30g along the thrust axis and at 10,15,20, and 25 g along the two transverse axes.

During the first run, with vibration along the thrust axis at 15 g, the calibration relay contact bounced, but it operated satisfactorily after the run. During the second run, with vibration horizontal at 10 g, the calibration relay operated properly but was intermittent after the run. The run along the other horizontal axis was satisfactory. The second series of three runs, at 20 g vertical and 15 g horizontal, was satisfactory.

It was when we began the third series that we ran into serious trouble. Following the initial run along the vertical axis at 25 g, we discovered a loose screw and locknut inside the shell. Since that threatened the mechanical integrity of the entire assembly, we immediately stopped the tests. I discovered that the GM counter was hot to the touch and, upon checking further, found that an abnormally high current was being drawn from the batteries powering its high-voltage power supply.

Thus, the test results were mixed, requiring a return to the design laboratories at both NRL and Iowa City. They would have to address the problems with the satellite shell and internal structure, and I would have to tend to the GM counter and relay problems.

Upon further checking the instrument package back in Iowa, I discovered a small crack in the GM counter’s ceramic insulator. It had allowed some of the internal gas to escape, causing it to arc and fail.

The 700 volts required to operate the GM counter presented a special problem. That voltage can be easily managed at sea level pressure where even a small air gap provides adequate insulation. However, as the air pressure is reduced, some electrons can pass across the gap, and a phenomenon called corona discharge begins to occur. That results in a high current flowing between the conductors, effectively shorting out the GM detector. The net result of that process is interference with the operation of the counter, overheating of components, and, eventually, destruction of the power supply.

The original design called for the Vanguard cosmic ray instrument to be sealed in an airtight container. As long as normal atmospheric pressure was maintained

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within that container, the corona discharge would not occur. However, we wanted to protect against the possibility that the container might leak. That required sealing all conductors carrying high voltage with some type of solid insulating material. However, the epoxy that we tried constrained movement of the base of the counter where its insulating terminal and seal were located. Vibration flexed the assembly enough to crack the epoxy and insulating terminal. That allowed some of the counter’s gas to escape.

It was clear that I had to improve the high-voltage insulation. That problem con­tinued to plague me in one form or another throughout the next 18 months, including during my later work at JPL.

Despite that result, I was optimistic, as my package’s overall mechanical design seemed to be sound. Other than the problems with the relay and counter, operation was satisfactory for all of the package’s electronic components and circuits, and the electromechanical tape recorder operated satisfactorily both during and after the tests.

That Monday, 1 July 1957, marked the official beginning of the IGY. Many individuals in the United States were working hard to make sure that we could launch a satellite during the next 18 months.

August 1957 Another vibration test at NRL was due in mid-August. We set about to put the prototype instrument package, referred to by then as PT3, in what we hoped would be its completed form. On 19 August, I boarded the plane for Washington, again hand carrying the prototype unit. After several days of work to install the instrument package in the satellite shell and set it up for the test, the all-important vibration test was made on 22 August.

The problem with the GM counter had not been solved. I had encapsulated the entire end of the GM counter and its mounting flange in a block of solid epoxy. Sometime during the second test, arcing again occurred. It caused the recorder tape to be nearly blank, even though the recorder operated perfectly throughout the test. The blank tape was a result of the method of encoding the data. Blank recordings were to be seen later after the successful Explorer I and III launches, when the pulse rate from the counter was very high for a different reason. That is a story of its own, as related in Chapter 12.

We continued with more of the vibration tests. In addition to the GM counter problem, several problems were again encountered with the satellite structure. Shortly before the final run, we noticed that the top of the satellite shell was deformed, and upon opening it, we found that our instrument package had broken entirely away from its supporting structure. Although it had been bouncing around for the last bit of the test, slamming against the top of the satellite shell to dent it, there was no apparent damage to our instrument. Thus, I was pleased with the instrument design

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and construction, including the fact that the tape recorder had behaved as planned. I returned home the next day.

Careful examination of the GM counter back in Iowa City revealed that the latest encapsulation technique still did not cure the problem. Although the block of epoxy firmly anchored the ceramic insulator, the swaying of the rest of the counter relative to its mounting flange again cracked its insulator. After that test, I worked out a variation of the encapsulating and mounting arrangement that permitted the counter and its insulator to move in unison without damage.

After those tests, NRL was under even greater pressure to improve the design of the satellite internal structure. At Iowa, in addition to further work on insulating the GM counter, I needed to make a number of additional changes to clean up our design and make its operation more dependable.

But first, I wanted a break. During the last week in August 1957, I left the frenetic pace at the laboratory for some rest and recreation with my much-neglected family. We had discovered the attractions of family camping vacations during two trial camping trips during the preceding summer. A short stay at Devils Lake, Minnesota, for our first introduction to tent camping was followed two months later by tent camping along the way as we drove west to visit Rosalie’s family in Seattle. Those were highly satisfying experiences and showed us that camping (true camping, in a tent) provided a complete break from the pressures of work and home, a valuable collective family experience, a close contact with nature, the thrills of encountering new horizons, and an inexpensive way to take extended vacations.

We were so excited by those early camping experiences that we decided to under­take our first extended pure-camping trip. That last week in August, Rosalie and I took preschool-aged Barbara and Sharon on a six day canoe-camping trip. This was in the Boundary Waters Canoe Area in the Quetico-Superior Parks in northern Minnesota and southwestern Ontario. Driving through Ely, Minnesota, to the end of the road, we rented a canoe at the southern end of Moose Lake. From there we canoed and portaged across Moose, New Found, and Ensign lakes and passed onto Bass Lake, where we found an isolated, small island that served as our home for the next four days.

We were amazed by the diminution of human presence that resulted from the portages. Moose Lake, accessible by road at its south end, and New Found Lake, directly connected with Moose Lake, were crowded along their lengths with canoes, sailboats, and speeding motorboats. After a short portage of about 25 rods, on Ensign Lake, we encountered only three canoes (one with a small outboard motor) during the time it took to traverse it. The portage to Bass Lake was 53 rods, enough to cut the average traffic density to only three canoe parties per day (none with motors).

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In addition to the absence of people, the seclusion of the island in Bass Lake had additional advantages—fewer bears and mosquitoes. We all had a great time with the routine of camp life, hiking, fishing, very brief dips in the frigid lake, sitting around the campfire, and restful sleep. We started as camping novices but ended with enough confidence to undertake many camps throughout the United States during the entire period that the children remained at home. Even after the children left, Ros and I continued our camping forays for many more years.

We returned much revitalized to our home on Rochester Avenue on Saturday, 31 August. After a Sunday to reestablish our usual home routine, Rosalie began arranging for another important family milestone, Barbara’s entry into kindergarten. And I went back to the laboratory.

October 1957 I looked forward to the push to deliver our prototype instrument package for what we hoped would be its final acceptance tests. As indicated earlier, that was already running several months late, partly because of the immensity of our task in completing the instrument, but also because of delays at the NRL in completing the final satellite shells, antennas, separation mechanisms, receivers, and transmitters. Both NRL and we were saved from major embarrassment, however, by the fact that the launch vehicle development was lagging substantially. Nevertheless, we all felt tremendous pressure.

During the summer, my only enrollment for university credit had been in research, and my work on satellite development easily fulfilled that requirement. In September, I felt that I had to continue pushing toward my degree with my course work and signed up for Theoretical Optical Physics and Quantum Mechanics, two very challenging courses. It turned out that they had to be dropped later when our program was shifted to the Jupiter C launch vehicle.

During the following weeks, I busied myself on many final details. My first sub­stantial task was to process and analyze the data that had been recorded during the recent vibration tests at NRL. I continued with temperature and vacuum tests of the recording and playback amplifiers and worked on final assembly of the full instrument stack.

I also hurried to make another change in the tape recorder. I had a growing uneasiness about the Mark III tape-advancing ratchet drive. By good fortune, Frank McDonald brought a newly available component to my attention—a solenoid that was designed at G. H. Leland Inc. to rotate wafer switches. I quickly adapted that device, resulting in the final Mark IV recorder, as seen in Figure 5.8. That final version of the tape-advance drive was fully balanced for steady state rotation, translational acceleration, shock, and vibration, and it operated dependably throughout the rest of the developmental program, and, eventually, in orbit.

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I was in the final stages of making the conversion to the Mark IV recorder when the Soviets orbited Sputnik 1 on 4 October 1957. I continued with that task for a short time, even after I began talking to JPL and Vanguard program officials and engineers about shifting our instrument from the Vanguard to the Jupiter C launch vehicle. The final solenoids and ratchets were prepared in the University of Iowa instrument shop but were fitted onto the flight units at JPL after I arrived there.

In mid-September, Kittl at the Signal Corps Engineering Laboratories reported on the results of their efforts to design a good high-voltage power supply to drive the GM counter. Superior to my design, it was immediately adopted for inclusion in our package. They delivered a working unit near the end of September, and then collected and pretested kits of parts, which we assembled on our circuit boards. Through that arrangement, I developed great admiration for the highly competent engineers at the Signal Corps Engineering Laboratories. The ones with whom I worked most directly were, in addition to Kittl, Paul Rappaport and George Hunrath.

I completed my preparations for the next vibration test a little ahead of schedule, so that I could attend the CSAGI Conference on Rockets and Satellites in Washington,

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D. C., during the week of 30 September through 5 October 1957. The story of the astonishing announcement of the Soviet launch of Sputnik 1 during that conference, and of its impact on the University of Iowa satellite experiment, is related in the next chapter.

ith the launch of Sputnik 1 on 4 October 1957, all reservations about the use of military hardware for launching a U. S. satellite evaporated. After all, the Soviets had just used a military rocket for that purpose. Their satellite was flying over many nations of the world, with no one objecting to any violation of their air space sovereignty. Von Braun, Pickering, Van Allen, and their collaborators had been dreaming of this opportunity.

As related in the last chapter, the essential elements of a satellite-launching version of the Jupiter C launch vehicle had been quietly evolving. Two satellite designs, both containing the State University of Iowa (SUI) cosmic ray instrument, were also well advanced. The Army Ballistic Missile Agency (ABMA)-Jet Propulsion Laboratory (JPL)-SUI version existed as a paper design, while the (still externally unknown) JPL design had already edged into the prototype hardware stage.

A word about Deal, the name coined at JPL for this satellite project. The most likely account of its origin is that the term surfaced well before Sputnik, while the Reentry Test Vehicle (RTV) was being developed and tested. A number of the JPL scientists, including Jack Froehlich, Henry Richter, Leonard R. Piasecki, Al E. Wolf, and John G. Small, were avid gin rummy players. They played during aircraft flights, in motels, in conference rooms, and wherever else they found themselves with free time. One account says that immediately after the first successful firing of the RTV-Jupiter C in 1956, they were ready with their cards, and one of them called out, “Deal!”1

A second version of the story attributed the Deal name directly to Jack Froehlich. A formidable poker player, he is claimed to have bestowed the name after the first Sputnik launch with the remark, “When a big pot is won, the winner sits around and cracks bad jokes and the loser cries ‘Deal’!”2

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Whatever account is true, the word Deal became a byword around JPL and was adopted as the internal pet name for the satellite project. The name was solidly established well before I arrived in Pasadena in November 1957, and persisted for a long time. The JPL even printed a set of playing cards that featured a drawing of Explorer I and the name “Deal” on their backs (Figure 8.1).

The Deal designation is used in this book for satellite work that occurred before the individual Explorer launches. Explorer names are used for events occurring after their respective launches.