Category Dreams, Technology, and Scientific Discovery

Leslie (Les) H. Meredith was born on 23 October 1927 and lived during most of his childhood in Iowa City. He received most of his college degrees from the University of Iowa: his B. A. in 1950, his M. A. in 1952, and his Ph. D. in 1954, all in physics. His timing was fortunate, as he became Van Allen’s first graduate student.

During parts of 1953 and 1954, Les went to Princeton University to work with Van Allen on the Matterhorn nuclear fusion project.6 Upon receiving his Ph. D. in 1954, he began his postgraduate career at the Naval Research Laboratory (NRL) in Washington, D. C., serving

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA 9

as head of the Rocket Sonde Branch and Meteor and Aurora Section. After the National Aeronautics and Space Administration was signed into law in October 1958, Les became one of the cadre of scientists transferred from the NRL to form what became the Goddard Space Flight Center in Greenbelt, Maryland. Serving for 12 years as chief of its Space Science Division, he provided outstanding leadership in the buildup of Goddard’s research staff and program. By mid-1970 he took over as deputy director of the Space and Earth Sciences Directorate, and after October 1972, he served for nearly three years as Goddard’s assistant director.

During subsequent years, Les moved through a progression of upper-level management positions, culminating in a short tour as the Goddard Center’s acting director. After his retirement as a federal government employee, he worked for nine years with the 13-agency U. S. Global Change Research Program.

In 2003, he and his wife, Marilyn, moved to their retirement home at North Myrtle Beach in North Carolina. Marilyn died in 2008, but Les has continued to reside there.

Les’ early balloons were launched from a football practice field on the east bank of the Iowa River from 16 June 1951 (beginning only five months after Van Allen’s arrival) through 26 January 1952. His scientific objective was to measure the incoming cosmic ray intensity as a function of altitude with a directional telescope using thin-walled Geiger-Muller (GM) counters. A concomitant purpose was to help the department gain initial experience with counters and coincidence circuits, telemetering techniques, and balloon flying.

That first Iowa balloon apparatus employed an array of three in-line, thin-walled, cylindrical, Victoreen-type 1B85 GM counters, with a coincidence circuit to form a directional telescope. An event from the center counter was counted, but only when the top and bottom counters were triggered at essentially the same time. Thus, only particles traveling vertically through all three counters were registered. The output of that telescope, along with an altitude measurement, was sent to ground by a frequency-modulated (FM/FM) telemetering system adapted from a design originally developed by Thomas Coor at Princeton University.7 Height-measuring barometers and transmitters taken from surplus weather radiosondes were included. Meredith’s circuits employed 13 miniature acorn vacuum tubes, each measuring about one-half inch in diameter and one and one-half inches in length.

His apparatus, with batteries, was assembled in a frame constructed of one-half inch, lightweight angle stock riveted together to form a boxlike structure measuring 15 by 15 by 30 inches. The gondola was completely covered with celluloid and partly covered with white paper to control the temperature of the instrument during its several-hour flight.

A number of inexpensive Darex type-J weather balloons of about six foot diameter were used to loft the instruments. Multiple small balloons were used rather than a single larger one. Not only were the smaller ones less expensive, but their use also freed the flights from the tight constraints of the Federal Aviation Administration— the larger balloons would have presented a potential hazard to aviation, whereas the smaller ones would not endanger the aircraft. The number of balloons was chosen so

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that their net free lift was about twice the total weight of the gondola and its rigging. For a payload weight of 27 pounds, a typical arrangement included nine balloons, each with 6 pounds lift.

Some of Les’ recollections about these earliest developments are entertaining and revealing.8 He stated, “The system test… was to take [the instrument] to the first high hill that you came to on the highway going south along the river, I think it was about five miles out of town, and then turn it on. The signal strength and counter operation were then checked at the receiving station, which was located in the attic of the physics building.” He continued, “Each balloon was of… some kind of rubber that had to be boiled just prior to launch to be flexible.” Recalling the field operation: “At launch, with the balloons at an angle because of any breeze, I and a helper ran with the payload until the balloons were high enough so the gondola wouldn’t swing down and hit the ground.”9

Out of Meredith’s seven flights in that series, the first two, flown on 16 June and 6 July 1951, produced somewhat noisy but usable data. Flight 3 failed to produce any usable data. Flights 4, 5, and 6 were flown with simple test equipment instead of with the more valuable instruments in order to work out some of the remaining technical details. The seventh and last flight in the series, launched 26 January 1952, produced good data throughout most of the flight. Preparation for the launch of the final flight is shown in Figure 1.1.

The three productive flights in this series served as the basis for Meredith’s master’s thesis, in which he established a new value for cosmic ray vertical intensity at that latitude for particles above an energy threshold that was lower than had previously been measured.10

he program of the International Geophysical Year—1957-1958 (IGY) provided a unique opportunity for cosmic ray research in general, and for us at Iowa City. As an active leader in the overall planning, James Van Allen had helped to shape both the general and specific character of the IGY program. In that role, he provided a great service to the research community.

In our Physics Department, Van Allen set the stage for the next few years of research. Acting to take advantage of the tremendous opportunity, he met in early 1956 with his graduate students to discuss possibilities for projects that they might undertake for their thesis work. By Carl McIlwain and Larry Cahill’s recollections, the list of possible projects that he placed on the table in that session included six cosmic ray, two auroral soft radiation, and two magnetic field studies.12 He envisioned that they could use a variety of balloons, ground-launched rockets, rockoons, and satellites. Those suggestions were in addition to the cosmic ray satellite experiment which he had proposed, and on which I had already begun work.

Following that session, decisions were made quickly, and specific proposals for IGY projects were submitted to Washington and funded. The work was undertaken with great enthusiasm and energy by the department’s graduate students, faculty, and staff.

Ground-launched rockets

The Iowa IGY research program, as it evolved, included experiments employing a mix of ground-launched rocket, balloon, rockoon, and satellite instruments. Carl McIlwain initiated the rocket program with an ambitious plan to probe the northern auroral zone.

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Mcllwain’s Fort Churchill flights At the time of the graduate student meeting, Carl was completing the work for his master’s degree. He received that in June 1956, with a thesis based upon the data from his Loki rockoon flights during the summer 1955 Davis Strait expedition.3

Van Allen’s suggestion that Carl might take advantage of the IGY program to fly some Nike-Cajun rockets at Fort Churchill, Canada, caught his attention, and he began thinking about various possibilities. He was captivated by the possibility that those rockets might be able to directly detect the particles that created the aurora, and thus shed light on the particle composition and energy spectra. It was known at the time, based on the alignment of the visible auroral features with the Earth’s magnetic field, that the auroral light was due to charged particles entering the Earth’s atmosphere. It was also known that at least some of those particles were protons in the 100 keV energy range, based on the presence of Doppler-shifted H„ and Hg spectral lines. The earlier direct detection of the soft auroral radiation by State University of Iowa (SUI) rockoons, however, indicated the presence of electrons, and Carl was eager to follow up on that new information.

To emphasize once again the trust placed by Van Allen in his graduate students, he assigned projects to them and then gave them tremendous freedom in seeing them through to completion. In this case, he designated Carl as the SUI chief scientist, and Carl bore full responsibility for preparing the instruments and conducting the field operation.

Carl’s first major technical challenge was to devise detectors that could detect and measure the very soft radiation that was capable of penetrating only very small amounts of material. Developing those instruments occupied much of 1957. He was joined in that work by Donald (Don) Enemark, a second-year electrical engineering student, and Donald (Don) Stilwell, an undergraduate physics student. They developed and built instruments capable of detecting the low-energy electrons in time for two Nike-Cajun flights that were scheduled for late summer 1957. Carl is shown working on one of his instruments in Figure 4.1.

Carl’s apparatus included three charged-particle detectors, a photometer, and a magnetometer. The first particle detector employed a thin thallium-doped cesium iodide (CsI [Tl]) scintillator crystal mounted on the face of a photomultiplier tube. Apertures, plus a 400 gauss permanent magnet, prevented electrons with less than 1 MeV energy from reaching the scintillator. The light sensitivity of the scintilla­tor crystal was reduced by a coating of 40 microgram per square centimeter alu­minum that was evaporated on its surface. Although the detector was sensitive to both protons and heavier ions, such as alpha particles, it was referred to as the proton detector.

The second particle detector was designed to characterize electrons. It, too, used a CsI (Tl) scintillator on the face of a photomultiplier tube. This one was annular in shape, with a thick plastic baffle filling the center opening. A ring aperture was located ahead of the detector, and an electromagnet between the aperture and scintil­lator focused electrons having specific energy ranges onto the scintillator. The pulses produced in the photomultiplier tube were integrated, and the resulting current was passed through a nonlinear network to produce a current that was roughly propor­tional to the logarithm of the electron energy flux over the range from 10-2 to 10+2 ergs per second per square centimeter per steradian. The magnet current was se­quenced through seven steps to make the detector sensitive to electrons in various energy ranges. The highest magnet current focused electrons with energies in the neighborhood of 100 keV The crystal on that second detector, too, was covered by a thin coat of aluminum to reduce its light sensitivity. That coating set the lower energy sensitivity of the detector at about 3 keV

A Geiger-Muller (GM) counter was included in the particle detector complement. It was surrounded by a one-sixteenth inch thick lead shield, except for a slit located

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next to a thin aluminum window in the side of the instrument package. It was sensitive to directly impinging electrons having energies in the range of 1 to 5 MeV In addition, it served as a low-efficiency detector for lower energy electrons through the process of converting electrons to X-ray photons (bremsstrahlung) in the atmosphere and the mass of the instrument. That arrangement provided a way to relate the new measurements to those made earlier with GM counters on the rockoon flights.

Carl included a photometer to measure the total directional intensity of visible auroral light. And a flux-gate magnetometer assisted in determining the pointing direction of the detectors during flight. Finally, a narrowly focused photometer was used on the ground during the flight to measure the auroral intensity straight above the launch site. In addition to being used to interpret the data, its output was used to help determine the best times to fire the rockets.

Carl’s two inaugural flights ran into difficulties. In the first firing (rocket number II 6.22F on 27 August 1957),4 the Nike first stage had not quite completed its burn when the two stages separated, and the Nike nudged the Cajun enough to break off the instrumented nose cone. Carl later reported that he found the payload in the muskeg the next day, and some of the electronics were still operable. His second flight (rocket II 6.23F on 30 August 1957 to a height of 70 miles) was somewhat more successful. The payload reached an aurora, but the Cajun, by chance, was pointing the instruments downward during the critical portion of the flight. Thus, he was not able to observe the incoming auroral particles.

Early the next year, Carl was ready with four more instruments of the same design. When he arrived at Fort Churchill, he found Les Meredith, who was by then working at the Naval Research Laboratory (NRL), with Leo Davis, also from NRL, already there with low-energy detectors that they had developed for flight on Aerobee-Hi rockets. They had made a successful flight (rocket NN 3.03F on 20 January 1958 to a height of 112 miles) by the time that Carl arrived and triumphantly announced that they had “already found what causes the aurora—low energy electrons, and that Carl might as well go home.”5

Believing that there was still new information to be gained, Carl proceeded, never­theless, with the checkout of his instruments (Figure 4.2). He made four flights during a 13-day period in February (II 6.24F on 13 February 1958 to 80 miles, II 6.25F on 16 February 1958 to 75 miles, II 6.26F at 05:34 UT on 22 February 1958 to 80 miles,6 and II 6.27F at 05:48 UT on 25 February 1958 to 80 miles). Fortuitously, a large solar flare occurred during the night of 11 February, a few days before his launches. It was quickly followed by a severe magnetic storm at the Earth, marked by decreases in the cosmic ray and neutron monitor intensities. That night was also marked by a bright red aurora that was observed over a large range of latitudes and longitudes. The following two weeks were characterized by moderate magnetic activity and frequent

occurrences of high-latitude visible auroras. The weather conditions at Fort Churchill were good throughout most of that period, permitting excellent observations.

Carl’s first three flights were technically successful, but data were obtained from only relatively dim and quiescent auroras. The flight on 22 February, for example, produced excellent data on the flux and energy spectra of protons and electrons but was not located in a very active region.

Those results were tantalizing, but not really what Carl was looking for. He de­cided to make a special effort to place his last rocket into a more active aurora and played the waiting game during the next several nights. His account of that launch read:

So, just visualize the scientists who were waiting around for me to get my last rocket off so they could fire theirs, and the impatience of the range safety people. Even though a graduate student, I still had control of when to launch. I told them, “Things are still not quite right.”

We waited at T minus 5 minutes night after night, and they said, “Come on, there is some aurora up there. Fire the thing,” but I insisted on waiting, and was very lucky. Upon seeing an auroral breakup just to the south of Churchill, I finally decided it was the time to finish the countdown.7

That launch (II 6.27F) finally took place in the early morning of 25 February 1958, and the Cajun reached observing altitude just as the aurora appeared over­head. The instrument remained pointed upward during the time of peak interest and

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produced the first-ever direct measurements of particles producing a bright auroral display.8

Enormous fluxes of low-energy electrons were detected, but they had an energy spectrum substantially different than had been seen earlier by both Les Meredith and Carl in the more quiescent auroras. Whereas the earlier measurements had revealed a broadly spread spectrum, the spectrum from this flight showed a strong peak at about 6 keV Carl concluded that the electrons had fallen through an electric potential that must have had a component aligned parallel to the magnetic field lines. That finding was highly controversial, as most of the theoreticians were quite convinced that it was impossible to have an electric field aligned parallel with magnetic field lines in a plasma. So he was hesitant about putting that conclusion into print, but did so somewhat later. Although still not universally accepted, the strong preponderance of belief today is that parallel electric fields do, in fact, exist and that they serve as a prime driver for the auroral particles.

I have tremendous admiration for Carl and his work. Following his arrival at Iowa, he very rapidly gained a deep understanding of physical processes when photons and charged particles move through space and interact with matter. The accomplished musician had become a virtuoso physicist!

The CSAGI Conference wrapped up its work on Saturday morning following the momentous announcement of the preceding evening. The closing session in the U. S.

CHAPTER 6 • SPUTNIK! 171

National Academy of Sciences’ Great Hall was marked by a mood of great excite­ment. But at the same time, it seemed anticlimactic and bittersweet. Of course, formal congratulations were offered to the Soviet delegates by Plenary Session chairman Lloyd Berkner. Soviet delegate head Anatoly Blagonravov took to the floor with understandable pride to speak at length about their Sputnik. On the blackboard, he sketched their new satellite, with its four antennas ranging from 5 to 10 feet in length. The main body was highly polished to make it more visible to observers on the ground. The total satellite weight of 184 pounds included 70 pounds of batteries that were expected to keep it transmitting for two to three weeks. He pointed out that this was not an instrumented satellite of the type called for by the IGY program, but rather, a test vehicle designed to demonstrate the effectiveness of the launching system. He indicated that its temperature measurements would determine, roughly, the effective­ness of the measures taken to control the internal satellite temperature. In addition, any later rise in temperature would signify that the sphere had been penetrated by a meteoric particle, allowing the escape of the nitrogen gas that circulated internally and served as a kind of air-conditioning system. The use of two frequencies at 20 and 40 MHz, he pointed out, was in general accord with the article published four months earlier in Radio magazine.19 The use of the dual frequencies was cited by Blagonravov as an advantage over the single frequency of 108 MHz being used by the United States, in that derivations of electron density in the ionosphere could be deduced from the signals.

It was obvious that many of the first Soviet satellite’s features were designed to maximize its political impact. Putting it up without scientific instruments was a shortcut to enable its launch ahead of the Vanguard satellites. The use of the highly polished surface ensured that it would be easily visible to the world’s population. The transmitter signals of 20 and 40 MHz, at a 1 watt power level, were easily received by the international community of radio amateurs and helped to make its reality more obvious throughout the world.

In Blagonravov’s remarks that morning, he conveyed an attitude that rankled U. S. attendees. He needled us for talking so much about our satellites before having one in orbit. That sentiment had actually been expressed quite explicitly a day earlier, when one of the Soviet delegates had told an American counterpart, “We will not cackle until we have laid our egg.” Although there was some justification for the Soviets’ more secretive approach (as we were later to discover to our chagrin in connection with a series of failed Vanguard launch attempts), Blagonravov seems to have entirely missed the point. The rest of the planners felt that much of the advance discussion was useful in (1) providing information that would help others who wished to cooperate in the tracking or other operational aspects of the program and (2) enhancing the scientific payoff. As Newell pointed out later, “in view of the fruitlessness of CSAGI’s efforts to elicit any such accommodation from the Soviets, either at Barcelona in 1956 or

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at the meetings in Washington, the remarks of their Russian colleague were doubly frustrating.”20

In spite of those negative aspects, admiration for the Soviet achievement was genuine and universal, and all at the session were able to applaud when Blagonravov ended his comments with his expression of hope that

this first step… would serve as an inspiration to scientists throughout the world to accelerate their efforts to explore and solve the mysteries and phenomena of nature remaining to be explored.21

Following Blagonravov’s remarks, John P. Hagen of the Naval Research Labora­tory reported that the U. S. Minitrack observing network had detected the transit of the satellite on its third or fourth orbit and that a regular tracking program was being established.22 Some stations of the Minitrack system, designed to operate at 108 MHz, were being hastily modified to operate at the Soviet frequency of 40 MHz as well.

He played a recorded tape of the telemetered signal, at which point Blagonravov’s normal reserve vanished, and he declared with obvious excitement, “That is its voice!”

Wrapping up the conference, working group members hurried to put their resolutions in order for the official reports. The resolutions were adopted in the Plenary Session, and the eventful conference was gradually brought to a conclusion.

In the final closing, the U. S. National Academy of Science president Detlev Bronk congratulated the conference on its achievements, and added his congratulations to the USSR IGY National Committee with respect to the launching of the first satellite. He stated:

All scientists are fellow explorers on the frontiers of knowledge, who rejoice and ben­efit in the discoveries and achievements of their colleagues. And so we of the United States rejoice in yesterday’s great achievement of our Russian colleagues and applaud their success.23

CSAGI president Sydney Chapman made the final statement for this first CSAGI Conference on Rockets and Satellites. He hinted at what others were saying privately:

The launching of the Sputnik without advance warning had taken tracking systems in the West unaware, and hence had reduced the amount of scientific observations that could be made. In congratulating the Russians on their “magnificent achievement,” Chap­man noted in his gentle, British way, that news of the launching had been “indirectly received.”24

Despite all of our attempts to put on a good face following the Soviet triumph, we Americans felt a palpable sense of betrayal.

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A corona discharge problem was described in Chapter 5 in connection with the development of the Vanguard prototype instrument much earlier at Iowa City. It reared its head again during the Deal I payload assembly in mid-December, when I discovered that the high-voltage power supplies had not been checked in a vacuum chamber.29 The JPL engineers stated that it was “no problem,” as the power supplies were “safe for direct shorting.” I knew from my testing at Iowa that electrical transients from arcing in a partial vacuum would destroy the supply. I had to prove my point by a series of overnight tests. They showed, first, that there was a problem, and second, that the encapsulation technique that I had worked out at Iowa solved the problem. After making that change, there were no further corona discharge incidents for the rest of the program, and the instruments operated in orbit without incident.

That episode was the most contentious one that I encountered during my stay at JPL. Without appropriate tests and an effective solution, there can be little doubt that our cosmic ray instruments would have failed soon after liftoff.

The first recordings of the Explorer III low-power telemetered data were obtained near the end of the first orbit by the JPL, Earthquake Valley, and Temple City Microlock stations, beginning at about 19:38 UT on 26 March. The next pass (pass 2) provided useful data at about 21:40 UT from Temple City. Pass 3 was received at Temple City at about 00:37 UT on 27 March, and Patrick Air Force Base (PAFB) received it a short time later. For the next five orbits, the satellite passed out of range south of the Microlock stations, and low-power telemetered data were not obtained. But when the orbit passes reappeared over the United States, Temple City immediately recorded a long 15 minute pass beginning at about 12:25 UT, and PAFB received the signal a short time later. And so it continued, with the Microlock stations receiving useful low-power data during essentially every orbit that carried the satellite over their locations.

A complete tabulation of the low-power continuously transmitted data similar to that for Explorer I was never assembled. Although the low-power data were used at JPL for engineering assessment, at Cambridge for the micrometeorite data, and for cursory examinations of the cosmic ray data, the primary focus of the data analysis efforts in our laboratory quickly turned to the tape recorder dumps telemetered by the high-power system.

The high-power system was completely new with Deal II. The satellite transmitter was turned on by ground command, and it remained on only long enough to transmit the data that had been stored on the onboard recorder since its previous readout. Typically, for a dump of the data from a full orbit of recording, the transmitter was turned on, the tape readout began after about two seconds, and it lasted for about six seconds. The transmitter was turned off by the onboard programmer immediately after completion of the readout to conserve battery power.

The first attempts to recover the onboard-recorded data from Explorer III were disappointing, as described earlier. It was not until I arrived in Huntsville the day after the launch that I was able to get an encouraging summary of the first 11 passes from Jack Mengel in Washington. There were at least hints of proper operation of the complete system during passes 2, 4, 6, 7, 10, and 13.11 It was only shortly after that, a full day after launch, that anything approaching the expected performance was achieved. On pass 14, Quito, Ecuador made the first completely successful single­command interrogation that resulted in the successful recording of data that had been accumulated over a full satellite orbit. That result was achieved increasingly as the stations became more proficient.

During the 44 day period of normal operation of the onboard storage and readout system, the satellite completed 523 orbits, and recorder interrogations were attempted

on 504 of them. Of those, 408, or 81 percent, resulted in useful data. The success rate was only about 23 percent on the first day but climbed steadily throughout the operating lifetime. By the third day of operation, the average daily success rate reached about 80 percent, and by the end of the operating lifetime, the rate was consistently averaging more than that figure. The interrogation success rate for the entire operational period is shown graphically in Figure 11.2.

There were several reasons for the disappointing initial performance. In the first place, this was the first use of the ground station command transmitters, and it took some time for the operators to resolve equipment issues and to fine-tune the procedures. Adding to the problem was the fact that the high-power system used a completely different and more complex operational mode than had been used for both the low – and high-power systems on Explorer I, and for the low-power system on Explorer III. After the interrogation command was transmitted, the responding data flow began after only two seconds. Thus, all equipment had to be pretuned, and the ground tape recorder had to be running before the command was sent. It took time for the operators to become proficient in this new and somewhat complex operation.

A second problem aggravated the data acquisition problem. It took time for the Vanguard Computing Center to accumulate enough tracking data to produce orbital predictions accurate enough to prealign the antennas. Since the entire high-power operation had to take place in a matter of seconds, there was no time to realign the

antenna if it had not been properly preset. By the end of the first day, the orbital prediction accuracy improved, thus contributing to the improved data recovery.

A very interesting account of the radiation belt discovery from the Russian point of view was published in History and Technology in 2000. The paper’s abstract reads:

The most important scientific discovery of the early space era—the 1958 discovery of the radiation belts of the Earth—was made in the context of Cold War rivalry between the USSR and the USA. The paper uses previously unavailable archival records to reconstruct the relative contributions of American and Soviet researchers and their interations [sic: iterations or interactions?] during the process of discovery. The former discovered what is now known

CHAPTER 12 • DISCOVERY OF THE TRAPPED RADIATION

as the inner radiation belt, while the latter observed the outer radiation belt and gradually came to realize the existence of two distinctively different zones of radiation. The uses of science for the purposes of Cold War political propaganda affected the behavior of scientists and led to the misrepresentation of the events in mass media.70

Although I believe that that paper is largely historically accurate, there are some differences in detail and interpretation between its account and the one presented here. Most of those differences appear to relate to the authors’ understandings of the timing and venues of various information releases.

Van Allen trained a long line of outstanding graduate students. During only the decade of the 1950s, he served as thesis advisor for 19 graduating students. By the end of his career, that number had grown to 60.5

Many of those students went on to seed the entire magnetospheric, interplanetary, and solar physics research arena. Some established major new programs at other in­stitutions. To list the earliest of those pioneering students, Les Meredith formed a new space research group at the Naval Research Laboratory in 1954, and in 1958 played a key role in establishing the outstanding space research capabilities at NASA’s newly formed Goddard Space Flight Center. Larry Cahill formed a space research group at the University of New Hampshire in 1959, and later led the space research labo­ratory at the University of Minnesota. Carl Mcllwain initiated a space research pro­gram at the University of California at La Jolla in 1962. John Freeman went to Rice University in Texas. And so it has continued through the intervening years.

Senior postdoctoral fellows, assistant professors, and associate professors orga­nized their own programs within Van Allen’s cosmic ray group, benefited from that association, and carried their skills and knowledge to other laboratories. In doing so, they played key roles in elevating the global space science program to its present scope and state of maturity. A few of those earliest pioneers were Frank McDonald, Kinsey Anderson, Pamela Rothwell, Sekiko Yoshida, and Brian O’Brian.

In addition to the physicists, a progression of outstanding engineers played key roles in the Iowa program, and also went on to help spread the Van Allen methodology. Most notable among those during the 1950s were Dale (Pete) Chinburg, Donald (Don) Enemark, Donald (Don) Stilwell, and William (Bill) Whelpley.

The researchers and staff were assisted by many highly talented and dedicated research aides, undergraduate students, instrument makers, draftsmen, data readers, clerical staff, and others. Many of those people also went to other locations to help spread the Van Allen way of doing things.

Soon after arriving at Iowa, Van Allen sent a proposal to the U. S. Office of Naval Research (ONR) for measuring the cosmic ray intensity at altitudes well above those reachable by balloons. The grant that resulted from that proposal was the beginning of a highly productive relationship, with ONR financial support for Van Allen’s programs continuing unbroken through the next 38 years.

Van Allen’s plan was to lift rockets by balloon to above most of the atmosphere before firing them, to reduce the effect of atmospheric drag on the speeding rock­ets. That combination, which quickly came to be known as the rockoon, permitted the attainment of very high altitudes with small but useful payloads at very low cost.

The idea for the rockoon had first been suggested to Van Allen by Lee Lewis of the U. S. Navy (USN) during the Aerobee-firing cruise of the USS Norton Sound in March

1949.1112 The concept was further developed in discussions during that cruise by the two of them, along with George Halverson of the USN and Siegfried Frederick Singer (known widely as S. Fred Singer) of the University of Maryland. The basic approach was to lift small, inexpensive, military-surplus rockets by balloons to an altitude of the order of 11 miles before firing them. When fired, the rockets would already be above the densest portion of the atmosphere. By thus avoiding the dominating influence of aerodynamic drag in the lower atmosphere, a much higher altitude could be reached than if the rockets had been fired from the ground. The initial rockoons made it possible to carry payloads weighing 40 pounds to peak altitudes greater than 60 miles for a cost for the rocket and balloon of less than $1800 for each flight. That compared with about $25,000 for each ground-launched Aerobee and $450,000 for each larger Viking rocket.

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Shipboard launching made the concept especially attractive and feasible for several reasons: (1) a ship can steam downwind to minimize the relative wind seen by the tethered balloon-rocket combination while the balloon is being inflated, (2) ships at sea can avoid populated areas and the possibility of damage by returning rockets that are fired in variable and largely uncontrollable directions, and (3) a wide range in geographic position can be covered from a single field installation.

The basic techniques and logistics of launching rockets from shipboard had already been worked out during the Aerobee firings from the USS Norton Sound. Launching rockoons from shipboard represented a straightforward extension of those practices, adding only the requirement for inflating and launching the large balloons. In view of the modest demands imposed on the ship by the rockoon operation, it was not necessary to schedule the ships for that exclusive purpose—the task was added for voyages already planned for other purposes. Thus, the incremental cost of the field support operations was kept very low.

The basic rockoon concept was reduced to practical form by Van Allen and Gottlieb, assisted by students Joseph Kasper and Ernest Ray, during late 1951 and 1952.13 1415

That first rockoon’s solid propellant propulsion unit was known as the Deacon. It was originally designed by the JPL in Pasadena, California, as a jet-assisted take­off (JATO) rocket for launching military aircraft from short runways. The Deacon was about six and one-quarter inches in diameter and nine feet long and had a thrust of 5700 pounds during a three to five second burn. They were mass-produced by the Allegheny Ballistic Laboratory of the Hercules Power Company located in Cumberland, Maryland.

Van Allen and Gottlieb developed several modifications to the mass-produced JATO rockets. Extra large tail fins, fabricated in the State University of Iowa (SUI) instrument shop, were required to assure stable flight when the rockets were fired in the rarified upper atmosphere. A thin-walled, aluminum, pressure-tight instrument nose cone, with an adapter to fit it to the rocket case, was developed to house the instruments. Finally, a hook arrangement was devised for suspending the rockets beneath the balloons during their ascent. The Deacon rocket assembly that resulted is shown in Figure 1.2.

Two types of scientific instruments were prepared for the first rockoon field expedition. One, prepared by Les Meredith as a part of the work for his Ph. D. dissertation, contained a single GM counter to measure the absolute intensity of cosmic radiation above the effective atmosphere as a function of height and geomagnetic latitude. His instrument was somewhat similar electronically to that which he used for his earlier balloon flights, but with a single omnidirectional GM counter substituted for the three-counter directional detector. Since the resulting omnidirectional counting rate

would be greater than the directional rate seen during the balloon flights, the new instrument required a pulse-scaling circuit to reduce the pulse rate to be transmitted to the ground. That electronic scaling circuit was adapted from a design by John A. Simpson at the University of Chicago. Five cascaded binary stages divided the counting rate from the GM counter by a factor of two to the fifth power, or 32. Most of the electronic circuits used the very rugged, low-power, and tiny Raytheon CK-5678 vacuum tubes that Van Allen had helped develop for the proximity fuses during WWII. The general arrangement of Meredith’s rockoon instrument is shown in Figure 1.3a.

Special Publications 14

A second instrument type was prepared by Robert (Bob) A. Ellis Jr. It used a chamber to measure total cosmic ray ionization. His instrument, also shown in Figure 1.3b, drew heavily on Meredith’s designs and techniques, but he used a pulse – ionization chamber rather than a GM counter as the principal detector. Individual pulse amplitudes, rather than counting rates, were telemetered. The chamber was a six-inch diameter sphere of 0.010 inch thick copper with an axial Kovar collector wire supported by ceramic insulators and with guard rings to eliminate electrical leakage across the insulators. The chamber’s pulses were amplified and lengthened before transmission by a circuit that produced an output pulse whose length was proportional to the input pulse amplitude.

Design of the research instruments for the rockoon flights benefited greatly from Van Allen’s experience in developing the proximity fuses for artillery shells during WWII. Robust components and construction techniques were used to withstand the

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA 15

high initial acceleration and severe vibration of the rocket firings. Most of the vacuum tubes adopted from the proximity fuse program for our purposes were the super­rugged, low-power, subminiature vacuum tubes identified as the Raytheon CK-5678. The larger 3A5 acorn tube that had been used in the transmitters for the balloon-borne instruments was found to be sufficiently rugged and was retained for the rockoon flights. The coils for the transmitters were hand-wound and adjusted for the proper frequency (74 MHz) and maximum power (one to two watts).

Testing procedures were remarkably simple and direct. Meredith recounted, “The only ‘G’ [acceleration] test was to put a working circuit board with its batteries on an arm on the drill press and see if it survived being spun. Only the ones that flew off and went flying across the lab failed.”16

Initial ground-launched tests of the rocket configuration (without the balloon or instruments) were made by Van Allen, Meredith, and Ellis at the U. S. Naval Ordnance Missile Test Facility at the White Sands Missile Range, New Mexico, during June and July 1952. Of three launches from the White Sands short tower, two flights were successful and demonstrated the rocket assembly’s mechanical ruggedness, flight stability, and performance. Two additional launchings of small rockets from a simulated balloon suspension rig verified the design of the coupling ring and hook, showing that the rocket’s line of flight would be within a few degrees of its static angle of suspension at the time of firing.

The first field expedition with Meredith’s and Ellis’ research instruments was on the U. S. Coast Guard icebreaker USCGC Eastwind during August and September 1952.17 18 The Iowa participants were Van Allen, Meredith, and technician Lee F. Blodgett. Ellis did not participate in the field exercise—Van Allen took charge of his instruments.

The icebreaker, under the command of Captain Oliver A. Peterson, progressed northward along the Davis Strait between Canada and Greenland, with its primary mission being to resupply the weather station at Alert Base on the northwestern shore of Ellesmere Island. The Iowa group and the balloon support team flew with their equipment from Westover Air Force Base in Massachusetts to join the ship at Thule in north Greenland. (The locations of those sites can be seen in Figure 2.13.) They were joined there by a group from New York University, who brought equipment for cosmic ray neutron measurements via balloons.

On board ship, the scientists were very ably assisted by Lieutenant Malcolm S. Jones from the ONR. The Iowa researchers set up their laboratory in a room below decks, as seen in Figure 1.4. The balloon crew arranged their equipment for inflating and launching the balloons on the ship’s helicopter deck. The ship departed Thule with the full complement of scientists and their gear on 29 July 1952, progressing

16

farther northward on its primary supply mission to Alert Base. Incidentally, on that cruise, they set a new record of 508 miles for the closest approach to the North Pole by a ship under its own power.

After the supply delivery at Alert Base, the ship returned to the upper end of Baffin Bay, where, during the period 20 August through 4 September, the SUI scientists made their rockoon launches from the mouth of Murchison Sound, about 100 miles northwest of Thule.

Open-neck, thin-film, plastic Skyhook balloons, 55 feet in diameter and made by the General Mills Aeronautical Research Division in Minneapolis, Minnesota, were used to lift the approximately 210 pound rockets and instrumented nose cones to firing altitude. A small SUI-made rocket-firing gondola, containing a timer, barometric pressure switch, and firing batteries, was suspended from the rocket’s tail fins by a light cord so that the rocket would break away once it was fired. The balloons were filled with enough helium to give about 35 pounds more lift than the combined rocket, payload, firing gondola, and rigging weight. That produced a balloon rate of rise of about 800 feet per minute, thus requiring nearly an hour for the climb to the firing altitude of about 40,000 feet. To keep the rockets and instruments warm during the long balloon ascents through the cold stratosphere, the rocket bodies were

painted black to absorb solar radiation and were covered by transparent plastic shrouds spaced away from the bodies by Styrofoam rings to provide additional warming by the greenhouse effect.

Preparations for launches were made by the Iowa University team, with very effective help by the ship’s officers and men. Lieutenant Jones installed and armed the rocket igniters. The balloon inflation and launching operations were conducted by J. R. Smith and J. Froelich from General Mills. Figure 1.5 shows the action on the ship’s deck during final preparations for one of the launches.

Seven flights were attempted, and all of the balloons performed admirably. How­ever, the first two rockets, both of which carried Meredith’s instruments, failed to ignite. On the second of those flights, data were received from the instrument for about 10 hours as it floated at balloon altitude, thus verifying the effectiveness of

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the payload temperature control arrangement and the adequacy of the battery packs. Those two initial failures were blamed on failure of the pressure switches due to their low temperature, and sealed cans of fruit juice were added to the firing gondolas to help keep the switches warmer during the balloon ascent. That technique was validated by a balloon test flight and was adopted for the rest of the rockoon launches.

The third rockoon flight, on 28 August 1952 (SUI flight number 3),19 was the world’s first ballistically successful rockoon flight. The rocket fired at an altitude of 38,000 feet, 55 minutes after release of the ensemble from shipboard. The rocket reached an estimated summit altitude of about 200,000 feet, or nearly 38 miles. The flight failed, however, to produce useful data from the instrument.

The remaining four rocket flights, made near 88 degrees north geomagnetic lat­itude, were also ballistically successful, with the best performance being a flight to over 55 miles height. Flights 4 and 5 carried Les’ instruments, while flights 6 and 7 carried the instruments that had been built by Ellis.

The ship returned to Thule on 5 September 1952, and the researchers returned from there to the United States by Air Force aircraft. As they returned to the campus that September, the Iowans were delighted that the practicality and effectiveness of the new low-cost rockoon technique had been convincingly demonstrated. Processing and analyzing the data from those flights occupied the scientists’ attention for some months after their return.

Van Allen prepared a paper for presentation to the American Physical Society in November 1952. That paper’s main purpose was to provide an overall summary of then-existing knowledge of the low-rigidity end of the primary cosmic ray spectrum. In the second half of that paper, he made use of the data from the two successful rockoon flights of Les Meredith’s instrument. One conclusion was that the new measurements confirmed and extended previous evidence for the marked flattening of the integral primary cosmic ray spectrum below a magnetic rigidity of about 1.5 x 109 volts.20

Van Allen reported separately that flights 6 and 7 of Ellis’ instruments produced good values of total cosmic ray ionization up to about 40 miles altitude.21

Meredith used the results from his two successful 1952 flights, combined with the data from a flight made during the following summer, for his dissertation.22 The flight data from those three flights spanned the range of geomagnetic latitude from about 88 to 54 degrees. His dissertation reported a value of unidirectional particle intensity averaged over the upper hemisphere of 0.48 (cm2 sec sterad)-1. He further stated that his measurements were consistent with a complete or nearly complete absence of primary cosmic ray particles of magnetic rigidity less than 1.7 x109 volts. (It should be noted for the sake of completeness that later, more sensitive and discriminating instruments did provide quantitative measurements of spectra at lower rigidities.23,24,25)

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA 19

Research using the new tools in such a demanding environment was sometimes less than successful. Flight preparations were always accompanied by the nagging ques­tion, will it work? New techniques were being developed, and meaningful progress involved an ever-present element of risk taking. As has already been described, the balloon, rocket, and rockoon field exercises had their share of failed flights due to unexpected wind conditions, rocket ignition failures, instrument failures, and other woes. On most expeditions involving multiple launches, at least some of the experi­ments failed.

That fact of life became painfully evident a little later when the first U. S. attempts were made (under intense public scrutiny) to launch Earth satellites. Throughout the first several years of spacecraft launchings, the success rate hovered around 50 percent. It was only as the technology became better established, and espe­cially with the demand for extremely high reliability accompanying the manned flights, that substantial gains were made in the success rates of scientific experi­ments.

During the 1950s, several field expeditions were mounted at Iowa that produced no usable scientific data. The following three cases are illuminating.

CHAPTER 4 • THE IGY PROGRAM AT IOWA 95

Frank McDonald and John Naugle developed a new set of instruments for flight on a Nike-Asp two-stage rocket at the White Sands Proving Ground.9 John was by that time working at the Convair Division of the General Dynamics Corporation, and the project was a collaborative effort between the two of them, their organizations, and the Cooper Development Company. Initial proof tests were to be made from the White Sands Proving Ground near El Paso, Texas.

The principal instrument was a unique form of recoverable camera that contained about 15 feet of nuclear emulsion on a flexible backing strip. The camera was triggered to begin operating at nose cone separation, which was programmed for about 220,000 feet (42 miles) altitude. The emulsion was to be moved past an aperture at a rate of about one inch per second.

The primary mission objective for the White Sands launch (in addition to proof of hardware) was the detection of micrometeorites. They were expected to produce a blackening of the film where each particle hit, and perhaps to leave some physical residue. It was planned that the instruments would be flown later in the auroral zone at Fort Churchill, where the primary objective would be to detect and help characterize the auroral radiation.

An array of additional instruments was included. A Friedman-type ionization chamber was designed to detect the solar Lyman-alpha intensity. A specially treated platinum photoelectric surface was intended to measure solar radiation at a wavelength of about 1800 angstroms. An X-ray spectrometer was developed to detect individual photons having energies greater than about 6 keV A photocell provided information about the orientation of the package with respect to the horizon and Sun. Tracking, telemetry, and a parachute recovery package were also included.

The firing at White Sands in January 1958 failed. The Nike booster burned errati­cally, causing the second-stage Asp to separate prematurely. The booster then started burning again and accelerated into the Asp “like a sledge hammer,” destroying it and the payload in the process.

A second attempt was made to launch that payload on 22 October. That attempt, also at White Sands, appears also to have been highly problematic. The data transmission was reported as poor, and no peak altitude was recorded for the rocket.

As far as can be determined, the originally envisioned Fort Churchill flights of that instrument complement were never made.

Larry Cahill’s work with his proton-precession magnetometer is recounted later in this chapter. After returning from his Antarctic expedition in late 1957, he turned to the preparation of his Ph. D. dissertation, using the data from those flights.

During that time, he continued with paying employment in the laboratory as a research assistant. As a part of that work, following a suggestion by Van Allen, he prepared several of his magnetometers for flight on two-stage Nike-Cajun rockets. He

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made a series of three flight attempts from the Wallops Island test facility on 21 and 23 May and on 27 June 1959. Unfortunately, none of those flights reached an altitude high enough to meet the primary scientific objectives.1011

Don Goedeke had assisted Van Allen in building the Loki II instruments that Van took on the fall 1957 expeditions, also described later in this chapter. In 1958, Don prepared a fleet of similar instruments for a pair of rocket-launching expeditions at Fort Churchill, Canada.

Searches of the available records failed to produce much information about this project—two references have been found. The Iowa City Press Citizen carried an article on 15 August 1958 that stated that Don, accompanied by engineering student Pete Chinburg, left on that day for the Hudson Bay region to launch a series of Loki rockets.12 The Annals of the International Geophysical Year list two series of University of Iowa flights of Loki II rockets at Fort Churchill, all of which contained cosmic ray and auroral particle detectors.13 The first series consisted of six flights during the period 3-8 September 1958. A summit altitude was reported for only one of those flights—the only one for which usable telemetry was received. A second series of seven flights was made two months later (4 October-8 November). Only one of those flights produced readable data, and it appears not to have reached a useful altitude.

It must be concluded that all of those flights had either instrument or rocket problems and that no scientifically useful data were obtained.

Many serious thinkers in the United States (including, among others, von Braun and his circle of close associates) understood the value of propaganda that would be attached to leadership in space. That was shared by many of the scientists and workers in the Soviet Union (including Korolev and his associates). However, the political leaders in both countries did not appear to have recognized its value before the shock of the Sputnik 1 launch. Nikita Khrushchev had been reluctant to authorize the first Sputnik launch, and was in bed at the time of the launch. He realized its importance immediately following the energized worldwide public reaction, and very quickly ordered the launch of Sputnik 2. Eisenhower, however, downplayed the importance of the event for the first several weeks and was spurred to action only following the Sputnik 2 launch in early November.

From the time of President Eisenhower’s first announcement in 1955 that the United States would launch an Earth satellite, until the launch of Sputnik 1 on 4 October 1957, those of us who were actual participants in the new space endeavor were developing our apparatus in an open manner. We believed that all would benefit if details of individual national programs were known to everyone, so that the resulting opportunities for cooperation would add value to the overall enterprise. The U. S. leadership was especially anxious to keep the satellite program separated from the classified Intermediate-Range Ballistic Missile and ICBM developments to encourage the emergence of an “open skies” policy.

To help emphasize that openness, the U. S. satellite program was set up as a civilian project, divorced from high-priority military programs and fully open to the public. To further underscore that separation, official responsibility for managing the satellite program was placed in the hands of the fully nonmilitary U. S. National Academy of Sciences.

The Soviet satellite program, on the other hand, was tied directly to long-range strategic missile development and was shielded from outside exposure by tight military secrecy. From the time of their initial brief public announcement that they would launch a satellite as a part of the Soviet contribution to the IGY, relatively few details of the Soviets’ work were available to the Western world.

It has sometimes been suggested that the satellite was launched at that exact moment so the announcement could be made at the Washington conference and, perhaps, even at that very cocktail party, in order to maximize its impact. I am convinced that launch activities in the USSR were not that precisely orchestrated, and that the Soviet delegates were not that prescient. The Soviet delegates at the reception appeared not to know before the rest of us that the launch had actually occurred. I believe that their project personnel back home had simply rushed to make the launch as

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early as they possibly could, and that it just happened to occur at that opportune moment.

On Saturday evening, I received a telephone call from my dad in Iowa City. He was recording our interview for his Monday morning radio program. We covered some of the details of the Friday announcement, reactions by the cocktail party’s attendees, and technical features of the satellite.

The national and international press had a field day. To sample the tone of the articles, the front page of the early edition of the Washington Post and Times Herald on 5 October screamed:

REDS LAUNCH EARTH SATELLITE
—Sphere Up 560 Miles, Russia Says.

Their final edition later that day expanded the coverage with its headline:

Space Satellite Launched by Russians, Circling Earth at 18,000 Miles an Hour;
Is Tracked Near Washington by Navy

Some of the articles that nearly filled page three of the 5 October edition of the

Washington Daily News were headed:

Reds Launch Satellite; Moon Next, They Say
—To the Planets by 1965

U. S. Caught Flat Footed

Reactions All Around the World
—Russian Embassy Opens up for Newsmen

How to Tune In

How to Look for It

Extensive news coverage continued during the following days and weeks. Some articles plainly reflected the U. S. surprise, shock, and disappointment in having failed to reach space first. The Baltimore News on 9 October started a series of articles to describe what happened and why. The introduction to that series read:

Most free world experts concede that in being the first nation to launch a man-made satellite into outer space, Soviet Russia won a tremendous scientific victory and an incalculable advantage over the United States in prestige and propaganda. Along with the realization of Russia’s triumph, the question is being asked: “Why was the U. S. beaten?”25

Criticism of our own program swelled, with banners such as “Navy Blocked Satel­lite, Generals Say.” Even more significant was the growing concern by many, both

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inside the federal government and among the public, that Soviet technology might be substantially ahead of ours. This was no small thing, considering the intensity of the cold war at that time. The grave concern was that the Soviets had the capability to deliver nuclear weapons over intercontinental distances well before us, and that that gave them a tremendous strategic advantage.

That situation was further reinforced by the orbiting less than a month later of a much larger satellite—Sputnik 2. Launched on 3 November 1957, it carried the dog Laika as a passenger! The U. S. reaction, by that time bordering on the paranoid, spurred weapons development and the general advance of technology as no other event was likely to have done. The apprehension extended beyond the military and technological arenas into everyday lives. Even school curricula were changed as a result to put increased emphasis on science and technology education. Homer Hickam, in his book October Sky, wrote sometime later of the period following the Sputniks’ launches:

Clutching books and papers, we slogged from class to class, our arms wrapped around the material. The same thing was happening in high schools in every state. Sputnik was launched in the fall of 1957. In the fall of 1958, it felt to the high school students of the United States as if the country was launching us in reply.26