Category Dreams, Technology, and Scientific Discovery

As mentioned in Chapter 10, the full interrogation log shows that many of the early Explorer III interrogation attempts of the onboard tape recorder either did not elicit observable responses from the satellite or usable ground station recordings were not obtained. During the first hours, both Van Allen and I eagerly sought information on the performance of the newly orbiting instrument, especially its onboard data recorder. As Van Allen was returning to Iowa City the evening of the launch, he called John Mengel at NRL during a plane change in Chicago.21 He learned of the interrogation success history up to that point, that is, of the passes over Antigua (immediate post­launch check—good response), San Diego (no response), Quito (not heard—response possibly heard at Lima but not recorded), and Antofagasta (no response). Thus, by that evening, there were only two indications of possibly successful interrogations. Only one of them was from the instrument after it had spent some time in orbit, and that response was uncertain.

I was en route from the Cape to Huntsville, Alabama, during that first evening and not able to find out about any successful postinjection interrogations until nearly midday the next day, when I was finally able to talk to Mengel in Washington. By then, additional at least partly successful interrogations (commands followed by an audible response) had been achieved from Quito, Santiago (two passes), Antofagasta, Quito (observed at Lima), and Havana. During that same period, five other passes elicited no response.22

The first interrogation that resulted in the receipt of a strong signal carrying a complete data dump (that is, of an onboard recording covering a complete orbit of the satellite), and that was successfully recorded on the ground, was finally achieved at about 21:00 UT (6:00 PM EST) on 27 March at Quito, over 27 hours after launch! A few more interrogations of variable quality were obtained during the next nine hours by South American stations. Before any of those recordings could be displayed in human-readable form, however, they had to make their way from South America, through customs, to the NRL Processing Center in Washington, D. C.

Within the next few days, the situation began to show substantial improvement. On Friday, 28 March, successful playbacks were recorded at Santiago (2), Antofagasta, Lima, Fort Stewart (2), San Diego, and Quito. During that same time, there were failures on only three attempts.

Enigmatically, the San Diego station operator reported, based on their listening to the audible playback signal while recording their 28 March pass, that there was a possible data dropout of three seconds about halfway through the roughly six second data readout. The data at the time of the gap had been recorded on the satellite when it was near its highest position in orbit. That suggestion of an apparent zero counting rate became tremendously important as events unfolded.

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On Saturday, additional successful recordings were made at Santiago (2), Lima, Antigua, Havana, Fort Stewart, and San Diego, with three other failures. By that time, the first ground station recordings of the data playbacks were just arriving at the processing center in Washington, D. C.

I reached Iowa City from Huntsville in mid-morning that Saturday. Driving imme­diately to the physics building, I checked with Van Allen, Carl McIlwain, and Ernie Ray on their progress with the Explorer I data. Eight weeks had elapsed since that satellite had been launched. Significant quantities of its data had arrived and were being examined. Although there was a growing feeling that Explorer I was detecting some unexpected real physical phenomenon, we had not yet concluded that we were seeing a high radiation intensity.

During that weekend meeting, in addition to the discussion of the Explorer I data, I briefed the group on the results of the Friday meeting at Huntsville. I had planned on putting two GM counters with different amounts of shielding in our IGY Heavy Payload instrument. But Van was hesitant about that, expressing his opinion that two GM counters would increase the chances for instrument failure.23 Although he insisted during that discussion on making one of the two counters a dummy, after we realized later that the Explorer I and III instruments were detecting high-intensity radiation of a largely unknown character, a live second counter was reinstated with added absorber material to help us in further understanding the new phenomenon.24

Also during that Saturday meeting, Van Allen and I agreed that I needed to move back to Iowa City as quickly as possible. We settled on a date of 6 April (only eight days thence) for my switch back to the SUI payroll. My family would return as quickly as we could settle our affairs in Pasadena.

I returned to my office in Pasadena on Monday for a week of whirlwind activities to wrap up my work there and prepare for our move.

Iowa’s role in the burgeoning space program was gaining wide publicity. On Sunday, 30 March, a CBS television camera crew arrived on the Iowa campus and began setting up their equipment. Walter Cronkite interviewed Van Allen on Monday (Figure 12.1), and his crew continued taping additional footage the next day.

Significantly, during that interview, Van Allen still made no mention of the pos­sibility of a region of unexpectedly high radiation intensity. The Explorer III data had not yet been examined, and he was, as was his usual practice, being careful to avoid premature speculation. Even later, on 20 April, when that interview was aired, no public mention was made of the discovery, even though, by that time, we were gaining an increased understanding of what our instrument was seeing, and a meeting had already been arranged in Washington for us to disclose our new findings.

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Even while the interview was being taped in Iowa City, the first Explorer III tapes arrived in Washington from several of the Minitrack ground stations. H. J. (Jack) Peake, the NRL engineer in charge of processing our data there, reported upon the arrival of those tapes in a short letter, as reproduced here.25

Van Allen’s First Lookat the Explorer III Data The day after his Cronkite interview, Van Allen went again to Washington to discuss a number of Explorer I and III matters. On Wednesday, 2 April, he took a taxi from his downtown hotel to the NRL facility in the southern corner of the District, where he conferred with Joseph Siry (relative to orbital data), John Mengel (data acquisition and data processing), and others of the Vanguard team.26

This is a good place to reemphasize the fact that NRL’s Vanguard staff provided outstanding support for the early Explorer program. Their Vanguard I had been launched just two weeks before the Explorer III launch, and after that launch, they were working around the clock to deal with tracking, orbit determination, data acquisition, and data processing simultaneously for three satellites.

As he concluded his business at the NRL, Van Allen took a taxi to the Vanguard Computing Center at 615 Pennsylvania Avenue. There he received a copy of Jack Peake’s letter and the film that had been prepared the previous day27:

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1 April 1958

To: Van Allen and Ludwig

Received from Minitrack stations at San Diego and Ft. Stewart, Ga. 4 1958 gamma recordings (2 from each station) yesterday. One record, San Diego at 1748 Z [UT] on 28 March, was of such high S/N [signal-to-noise] ratio that we transcribed it to the enclosed film record. On the film is pulse time code (1748 Z is marked on the film), detected signal, and 10 kc (needs some magnification to see peaks clearly).

Please accept the film record, compliments of the U. S. Navy! Will be sending along 1/4-inch tape transcriptions shortly.

Sincerely,

H. J. Peake Code 6413 Applications Branch Solid State Division

Putting that precious first Explorer III data readout into his briefcase, he returned to his DuPont Plaza Hotel room, stopping en route at a Peoples Drug Store to pick up chart paper and a few drawing supplies. Late into the night, Van read the data from substantial portions of the record, roughly computed the pulse rates with his slide rule, and plotted the data on a graph. He then charted the counting rate as a function of time. He completed it at about 3:00 in the morning, packed his work sheets and graph into his briefcase, and retired for the rest of the night.

He later recounted that, at that point, he was convinced “that our instruments on both Explorers I and III were working properly, but that we were encountering a mysterious physical effect of a real nature.”28

Although the original film from which he worked that night was apparently not preserved, his original notes and the resulting graph do exist in the University of Iowa Libraries, Department of Special Collections.29 Figure 12.2 is a reproduction of a portion of that graph.

Back in Iowa City Jack Peake also shipped copies of his 1 April letter and the strip- film recording of the San Diego data readout to Iowa City. Carl McIlwain recalled that he met a delivery person early in the afternoon, almost certainly on 2 April, at the entrance of the old Physics and Mathematics Building. Excitedly, he took the film to the basement, where he, Ernie Ray, Joe Kasper, and Herbert (Herb) Sauer quickly mounted it on a reel-to-reel microfilm reader. Carl had been saying for over a month that the transition from normal cosmic ray rates to zero counts was the key to whether it was from an instrument failure or high radiation fluxes. Quoting Carl, “and there it was!”30 Smooth transitions in the counting rate were instantly apparent.

At that point, Carl stopped looking at the film to pursue the then-paramount question. If high radiation intensities were actually being encountered, what would account for the apparent zero counting rates? He quickly lashed together a set of

equipment, using a GM counter and coupling circuit similar to those in the satellite instrument. Setting the counter in front of the X-ray machine that he had been using for his rocket instrument calibrations, he made a quick set of runs. Lo and behold, initially the pulse rate at the output of the coupling circuit rose as expected with increasing X-ray intensity, but it then fell off at higher exposure levels! At rates that should have been about 30,000 per second, the rate actually observed at the output of the circuitry was zero.

That behavior resulted from the characteristics of the GM counter and its coupling and scaling circuits. When an ionizing particle entered the counter and interacted with its internal gas, it produced a pulse on the counter’s central anode. That pulse took only a few microseconds to build. It decayed, however, at a much slower rate, depending on the resistance and capacitance in the circuit. At normal primary cosmic ray rates, the relatively leisurely decay was essentially complete by the time another particle arrived. Thus, all of the arriving particles produced pulses of full amplitude that were counted by the scaler circuits.

When two events occurred much closer together, however, the pulse for the second event started, not from a zero value, but from a higher value that still lingered from the previous event. The transition was from that higher value to, still, the fixed power supply voltage. Thus, the amplitude of the second pulse at the input

FIGURE 12.3 The note that Ernie Ray left on Van Allen’s door after Ernie and Carl Mcll – wain saw the results of Carl’s exposure of the GM counter to an X-ray beam. The note was scrawled on a sheet of paper that was used either earlier or later for some extrane­ous doodling. The exact date of the note is uncertain—the date at the top in Van Allen’s handwriting (5 April) could be the date that he filed it, not necessarily the date that he first saw it. The annotation at the bottom (3 April) is probably the date of the doodling, not necessarily the date of the note. This au­thor’s best judgment is that the note was written on either 2 or 3 April. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Libraries.)

to the scaler circuit was less than its full normal value. As the GM counter pulses became closer and closer together, the pulse amplitudes at the scaler input became smaller and smaller. Eventually, the pulse amplitudes became too small to trigger the scaler. When that happened, the scaler registered none of them, seeming to signify a zero rate.

Bolstering the tentative conclusion With that information, Ernie excitedly wrote his famous “Space is Radioactive” note (reproduced here as Figure 12.3) and posted it on Van Allen’s door.31 Although, of course, Ernie and Carl knew that space was not radioactive in the true sense of the word, the note clearly expressed their excitement and firm belief that the instrument was, in fact, encountering a real very high radiation level.

Van Allen returned from Washington to the Iowa campus sometime on 3 April. He met, either late that day or the next day, with Ernie and Carl to show his data plot. Carl then offered his data showing the GM counting rate during its exposure to the X-ray beam. The three, Van Allen, Ernie, and Carl, were immediately convinced that the only possible interpretation of the data was that Explorers I and III were encountering very high fluxes of radiation—radiation at least a thousand times as intense as the normal cosmic ray rate.

They quickly set about to make a more complete and detailed plot of the 28 March San Diego data. On Friday, 4 April, Ernie, representing his coworkers, penciled a

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second note to Van Allen that accompanied their data plot. Its first page read, “An analysis of data from 1958/. San Diego interrogates: 28 March 1948 Z.” Its second page read32:

From the preliminary information from Vanguard computing center, perigee occurs five minutes after the maximum latitude. Evidently interrogation also occurs near perigee. Thus the data show low (reasonable) counting rates near perigee. The interesting portion of the graph has equatorial crossings and apogee in it.

Evidently there is no hole in space. Rather, space is radioactive.

Very rough preliminary work with an Anton Geiger tube indicates that it stops putting out usable pulses when, if its dead time were zero, it would be counting 104-106/sec.

Data read and analyzed and supporting work carried out courtesy of Kasper, Mcllwain, Sauer, and Ray.

[Signed] Ernie Ray 4 April 1958

The first generation of spacecraft consisted of relatively simple payloads in which simplicity, reliability, and, in the United States, suitability for small launch rocket weight-lifting capabilities took precedence. Those spacecraft carried a single primary

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scientific instrument, plus, in some cases, one or a few secondary instruments and engineering sensors. Sputnik 1, Explorers I through V, Vanguards I and II, and Pioneers 3 and 4 were clearly in this category.

Vanguard II The Vanguard program continued to move forward. After some addi­tional disappointing launch failures, a successful launch on 17 February 1959 placed 21 pound Vanguard II into a durable orbit. It contained a single active scientific in­strument array—a pair of optical cloud cover scanners provided by the U. S. Army Signal Corps Research and Development Laboratory at Monmouth, New Jersey, un­der William (Bill) G. Stroud’s leadership. It depended on the satellite’s spin as it advanced in its orbit to trace a raster pattern that could be processed to provide a pic­ture of the Earth. Although the instrument operated perfectly throughout its operating lifetime, its success was marred by the fact that the satellite was nudged following separation from its third rocket stage, causing the satellite to wobble. Thus, the cloud cover instrument traced a much more complex path over the Earth’s surface, making it next to impossible to assemble coherent pictures.

Vanguard II also supported a secondary objective. Its clean, spherical shape, com­bined with the Vanguard tracking and orbit determination capabilities, permitted accurate measurements of satellite drag and therefore upper atmospheric density as a function of altitude, latitude, season, and solar activity. Among other things, Vanguard II showed that atmospheric pressures, and thus drag and orbital decay, were higher than anticipated in the region where the Earth’s upper atmosphere gradually fades into space.

SCORE The SCORE project initiated the field of satellite radio communications. The acronym stood for Signal Communication by Orbiting Relay Equipment. It was a program supported by the Advanced Research Projects Agency, with the payload supplied by the U. S. Army Research and Development Laboratory at Fort Monmouth, New Jersey. The payload consisted of a communications repeater, augmented by an onboard tape recorder that was capable of recording and delayed playback of voice messages. Launched on 18 December 1958, it broadcast the famous “Christmas mes­sage” by U. S. President Dwight D. Eisenhower. With an operating lifetime of 12 days, the communications objectives were completely met, including the demonstration of both real-time and delayed transmission from one ground station to another.

Probably more significantly, it met a major U. S. geopolitical objective. Launched only 19 days after the first fully successful test flight of an Atlas ICBM, and result­ing in the placement of the complete 8700 pound Atlas main stage and its payload in orbit, it represented an impressive new U. S. launch capability. Although billed as a peaceful scientific mission, SCORE demonstrated for the entire world that the United States was also finally capable of delivering nuclear payloads anywhere on Earth.

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The similarities between the SCORE and the earlier USSR Sputnik 1 achievements are striking. Sputnik 1 was launched only 44 days after the Soviets achieved their first fully successful test flight of an ICBM. Its declared scientific objective was, also, communications. But its main purpose was to demonstrate to the world a long-range strategic rocket launching capability. Thus, the two projects had similar objectives, and both placed impressive weights in orbit—over 14,000 pounds (rocket plus detached payload) for Sputnik and 8700 pounds (rocket plus integrated payload) for SCORE. In terms of implied nuclear capabilities, the two were about equal. The U. S. nuclear devices were physically smaller and lighter than their USSR counterparts, and could, therefore, be launched with smaller launch vehicles.

The main distinction between the two programs was that the Soviets were able to demonstrate their capability fully 14 months before the United States was able to do so.

The race to the Moon As soon as the first satellite was launched, mankind’s ev­erlasting fascination with the Moon kicked in. In the thoughts of some, orbiting the Earth was only a prelude to the much more exciting prospect of flight to the Moon. Both the Soviets and the Americans quickly set their sights on that goal.

Lunar missions introduced a new set of technical challenges. Not only must the rockets push the spacecraft to an initial speed of about 18,000 miles per hour to get them into Earth orbit, but they must speed beyond that to an initial velocity of about 25,000 miles per hour to escape most of the Earth’s gravitational pull and reach the neighborhood of the Moon. In addition, they require far more accuracy in initial aiming and in on-course trajectory control. Communication and tracking also presented new challenges because of the much greater transmission distances.

Information about first Soviet attempts at flights to the Moon is sparse because of their initial practice of outright denial of unsuccessful attempts. Information published in later years indicates that the Soviet program for lunar flights was actually formally approved as early as March 1958. Although the Miami Herald reported on 4 August 1958 that the Soviets had tried and failed to launch a rocket to the moon on 1 May,1 no other evidence can be found that they attempted a deep space launch that early. The first substantiated Moon attempt was made by the Soviets on 25 June 1958 with an SL-3 (A-1) rocket (derived from the SL-1 [A] rocket that had launched the first three Sputniks). That attempt failed.2

The U. S. Thor-Able 1 mission (sometimes referred to as Pioneer 0) was launched on 17 August 1958. The vehicle was a Thor Intermediate-Range Ballistic Missile, topped by a modified Vanguard third-stage solid rocket. On that attempt, the first-stage rocket exploded 77 seconds after liftoff, probably due to a failed turbopump bearing.

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I was at Cape Canaveral preparing for our Explorer V launch at that time and witnessed the Thor-Able attempt. My journal reads:

Well, the moon attempt was a failure. After 77 seconds it blew. I saw it from Hangar S, five miles away, Bill Whelpley from one half mile (RIG [Radio Inertial Guidance] site). Bill said after it climbed 300 or 400 feet, a small fireball appeared for three seconds about the diameter of the second stage, at the point where stages one and two join. I didn’t see this from Hangar S, and to me it appeared to climb normally until 77 seconds, when two white puffs of smoke were seen in quick succession. Following the first one, several small pieces were thrown off.

It looked like it might have been an engine explosion.

The beaches were lined for the shot. It is surely a shame it failed, because now USSR will have another chance to beat us.3

The instrument complement on this 83 pound payload consisted of a nonlinear search coil magnetometer provided by the Space Technology Laboratories Inc. (STL) to measure the Earth’s magnetic field and determine whether the Moon had such a field. The STL also provided a microphone assembly to detect micrometeorites. The Naval Ordinance Test Station provided an image-scanning infrared television system to take low-resolution images as the craft approached the Moon.

Thor-Able 1 marked the entry of an important new organization on the U. S. space scene. In September 1953, Simon Ramo and Dean Wooldridge had formed the Ramo-Wooldridge Corporation to work directly with the U. S. Air Force on problems of system engineering, including development of the Atlas Intercontinental Ballistic Missile (ICBM). Adolf (Dolf) Thiel, one of the original group of German rocket experts brought to the United States following World War II, joined them in 1955. The Ramo-Wooldridge Corporation was renamed STL in December 1958. That orga­nization (later spun off to form Thompson Ramo Wooldridge and, later still, simply TRW) was responsible for a long string of space missions during the 1950s, 1960s, and 1970s, of which Thor-Able 1 was the first. TRW has remained a prolific contractor for NASA and military space efforts.

The Soviets followed with another failed attempt on 23 September. That Luna 1958A launch vehicle structure failed after 92 seconds of flight, and the vehicle exploded. It is believed that that spacecraft weighed about 800 pounds and carried an instrument complement somewhat like the later successful Luna 1.4

The United States achieved a modest space first by sending a craft well beyond low Earth orbit for the first time. Under the banner of the newly formed NASA, the Air Force launched Pioneer 1 on 11 October 1958, again with their Thor-Able launcher (Figure 14.1). Although Pioneer 1 failed to achieve its primary objective of reaching the Moon due to a programming error in the upper stage, it did travel out to a distance of about 70,000 miles from the Earth.

Pioneer 1 looked much like the earlier Pioneer 0, except for the addition of one new instrument. Time had permitted the development and addition of a chamber to measure total ionization as the probe moved through the radiation zone.

The ionization chamber experiment was a cooperative effort between scientists at STL and Carl McIlwain at Iowa. The STL experimenters, Alan (Al) Rosen, Charles (Chuck) P. Sonett, and Paul J. Coleman Jr., carried the primary responsibility for preparing the instrument, while Carl specified the characteristics of the chamber and participated in its preparation, calibration, and data interpretation.

The chamber, produced by Nicholas Anton and his engineers at the Anton Elec­tronics Laboratories under Carl’s guidance, consisted of an aluminum-walled vessel with a volume of about 2.5 cubic inches. It was initially filled with pure argon to a pressure of about 193 pounds per square inch. The design of the electronics that followed the chamber was based on the circuit that Carl had developed for the scintillation counters in Explorers IV and V Its most noteworthy feature was a log­arithmic response that provided measurements over a huge dynamic range so that it could determine the radiation dosage both in the midst of, and outside, the radiation zone.

The chambers were carefully calibrated before launch with a Cobalt-60 radioactive source at the Radiology Department of the University of California, Los Angeles

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Medical Center. It was determined later, however, that the Pioneer 1 flight chamber had had a slow leak, and that by the time of the flight, the pressure had dropped to about 22 pounds per square inch, with a concomitant reduction in its sensitivity. A correction for that change, as well as corrections for other instrumental errors and temperature effects, was used for all work on the data.

For the first 17 minutes of the Pioneer 1 flight, the telemetering system was dedicated to monitoring vehicle performance. Then the scientific instruments were turned on so that useful research data began when the spacecraft was about 2200 miles from the Earth’s surface, and at about 32 degrees north latitude and 30 degrees west longitude. Data recovery continued until the spacecraft reached about 22,400 miles height at about 6 degrees north latitude and 0 degrees longitude. Unfortunately, scientific data were not recovered during the rest of the flight, including the return trajectory.

Analysis of the Pioneer 1 ion chamber data provided several significant results. (1) It verified by direct measurement the extent of the region of high-intensity radiation that had been inferred earlier from the lower-altitude Explorer I, III, and IV data. (2) Throughout the altitude range from about 2500 miles to 15,000 miles from the Earth’s surface (to 4.8 Earth radii from the Earth’s center), the level of ionizing radiation remained in excess of two roentgens per hour. (3) When the spacecraft was outward bound at about 20 degrees north latitude, peaks of the radiation belt intensity occurred at heights of about 6600 and 7400 miles (2.6 and 3.4 Earth radii from the Earth center). The maximum level of radiation at those locations was about 10 roentgens per hour. Results from later flights showed that the second peak was accurately correlated with the center of the outer radiation belt.5

The Soviets tried again with Luna B on 12 October 1958, just a few hours after the Pioneer 1 launch. Although details of its payload are also not known, it is presumed that it was essentially the same as Luna 1958A. The rocket exploded 104 seconds into the flight.

The United States tried again on 8 November with Pioneer 2, a craft that was gen­erally similar to Pioneer 1, but with the addition of a proportional counter telescope by John Simpson’s group at the University of Chicago. Another rocket failure—the third stage separated from the second and failed to ignite, and the spacecraft fell back to Earth over northwest Africa. Carl McIlwain’s ion chamber did, however, provide useful information. Correlation with the Explorer IV data showed that the counting rate at about 1000 miles height was relatively independent of longitude, but strongly dependent on geomagnetic latitude, thus supporting the model of the trapping region that had evolved by that time. In addition, use of the ion chamber data and the data from the proportional counter telescope showed that the trapped

particles were a combination of electrons and protons, rather than high-energy elec­trons alone.

And another try by the Soviets on 4 December: Luna C. The payload, too, is presumed to have been a copy of Lunas A and B. The rocket exploded after 245 seconds of flight.

A very productive partial success was finally achieved two days later with the NASA – Army launch of 13 pound Pioneer 3 on 6 December 1958. It was the first attempt with the Juno II launch vehicle developed by the Huntsville group. That vehicle substituted a larger Jupiter rocket for the Redstone booster that had been used in the earlier Jupiter C-Juno I configuration for Explorers I, II, III, IV, and V

The form of the payload was a cone attached to a short cylindrical section, with an overall height of about 24 inches and a cylinder diameter of about 10 inches, as seen in Figure 14.2. It was developed primarily by the Jet Propulsion Laboratory (JPL) with two main objectives. One was to demonstrate a close flyby of the Moon. Two

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photocells were set to trigger by the light of the Moon when the probe was about 20,000 miles distant, to serve as tangible proof of the accomplishment.

The second objective was to make radiation measurements throughout the flight to further substantiate and map the newly discovered high-intensity radiation around the Earth. Van Allen served as the principal investigator for that experiment, which employed a pair of Geiger-Miiller (GM) counters sized to measure the full intensity of the high-intensity radiation. He, aided by rising undergraduate student Louis (Lou) Frank, calibrated the payload’s detectors in the Iowa laboratory, using a variety of radiation sources, as shown in Figure 14.2.

That attempt with the new launcher also failed to reach the Moon. Early depletion of propellant caused the first-stage engine to shut down 3.7 seconds early. Although that prevented the vehicle from reaching escape velocity, the craft did climb to a height of over 66,000 miles before falling back to Earth.

Although the flight fell short of its first objective, it met the second one splendidly. In fact, its failure to reach escape velocity, with the instrument falling back to Earth, provided a second pass through the region of high-intensity radiation. While the outbound trajectory passed through the heart of what came to be referred to as the outer belt, it only grazed the core of the inner belt. But the return trajectory passed through the central cores of both belts and proved beyond any possible doubt the presence of two distinctly different regions, as seen later in Figure 14.4.6

The two GM counters in Pioneer 3 had distinctly different characteristics. The first was an Anton type 302 counter similar to the one used in Explorer IV It was followed by a very wide dynamic range scaler and filter arrangement first suggested by this author in April 1958.7 Although the Explorer IV schedule had been too tight for me to develop that circuit at the time, JPL engineers developed it for Pioneers 3 and 4. It had the feature that multiple scaling factors of 512, 8192, and 131,072 could be telemetered over a single channel.8 That wide dynamic range permitted the instrument to track a variation of over 2000 to 1 in counting rate during its transit through the region of high-intensity radiation.

The second GM counter was a much smaller one, specially built for this mission by the Anton Electronic Laboratories as their type 213. Its effective size was about one-tenth that of the 302 counter, and its primary purpose in Pioneer 3 was to serve as an ambiguity resolver for the 302 counter.

The Soviets finally approached the Moon on 2 January 1959 in spectacular fashion. Using a redesigned R-7 launch vehicle, their spacecraft (variously referred to as the First Cosmic Rocket, Mechta, Dream, Luna 1, or Lunik 1) was intended to impact the Moon, although that was not admitted by the Soviets until much later. A malfunction in the ground-based control system caused an error in the rocket’s

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burn time. Although missing its primary objective, it passed within 3700 miles of the Moon’s surface and became the first man-made object to escape from Earth orbit to take up its own orbit around the Sun. That orbit lies between the orbits of Earth and Mars, where, barring collision with some other object, it will dwell for the ages to come.

Luna 1, weighing nearly 800 pounds, carried an impressive array of instruments. They included GM counters, scintillation counters, a Cerenkov detector, a magne­tometer, a micrometeorite detector, and traps for detecting low energy protons. The data provided new information on the Earth’s trapped radiation, showed that the Moon did not have a substantial magnetic field, and made the first direct observations and measurements of the solar wind, a strong flow of ionized plasma emanating from the Sun.

While outbound, at a distance of about 74,000 miles from the Earth, the spacecraft released a cloud of sodium gas, creating an orange vapor trail. That cloud was easily visible from the neighborhood of the Indian Ocean, and accomplished two purposes. It provided a visible confirmation of the vehicle’s trajectory and served as an experiment on the behavior of gas in the vacuum of outer space.

The spacecraft also contained a number of medallions for dispersal around the point of intended lunar impact to perpetually mark the feat.

The U. S. Pioneer 4, launched on 3 March 1959, followed Luna 1 to the general neighborhood of the Moon. It passed about 37,000 miles from the Moon and entered its own independent orbit around the Sun. The records generally refer to it as a successful mission, even if it did not pass close enough to the Moon to trigger its photoelectric sensor. The significance of the accomplishment suffered somewhat by being greatly overshadowed by the Luna 1 flight two months earlier. The Pioneer 4 spacecraft weighed only one-sixtieth the weight of Luna 1 and passed the Moon at about 10 times the distance.

The Pioneer 4 spacecraft was similar to Pioneer 3—its only difference was the inclusion of additional shielding around the type 213 GM counter to provide bet­ter information about the penetrating ability of the charged particles. Van Allen’s set of objectives for that flight included a resurvey of the intensity structure of the Earth’s radiation zones, an examination of temporal changes that might have oc­curred since the Pioneer 3 flight, a rough further determination of the composition and spectral character of the radiation, and a look in interplanetary space for re­gions of plasma that might contain particles energetic enough to trigger the GM counters.

One important additional contribution of the Pioneer flights was to shake down and quantify the performance of the Microlock tracking and telemetry system developed

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by JPL. That system, using the 85 foot antenna dish at Goldstone Lake in California, turned out to be capable of recovering the signal from the miniscule transmitter on the 13 pound Pioneer 4 to a distance of over 400,000 miles. Even there, transmission apparently stopped only because of the expected exhaustion of the probe’s batteries. That telemetry system was a precursor to the wonderful capability that JPL has steadily improved and used over the years for tracking and recovering the data from a long progression of deep space excursions.

The Pioneer 4 scientific productivity was marred slightly by two factors. The largest of the three scaling factor taps for the 302 GM counter was lost due, apparently, to a major physical shock during the burning of one of the rockets. The performance of the other two taps was normal. Second, telemetry data were lost for about half a minute, just as the probe was passing through the core of the outer radiation zone, that is, between about 2.5 and 4.5 Earth radii.

The Soviets made another attempt to impact the Moon on 18 June 1959, but the vehicle’s guidance system failed.

Finally, following a 12 September launch, the Soviets succeeded in making the first physical contact with the Moon. After a 33.5 hour flight, Luna 2 impacted at a point west of Mare Serenitatis. To mark the event, two small spheres with their surfaces covered with stainless steel pentagonal elements were ejected and exploded shortly before spacecraft impact, to disperse the pendants around the impact site. The pendants were emblazoned with the USSR Coat of Arms and the Cyrillic letters CCCP. Some 30 minutes after the spacecraft impacted, the third rocket stage also struck the Moon. Another device on that rocket—a capsule filled with liquid and with suitably engraved aluminum strips—marked its impact site.

Luna 2, shown in Figure 14.3, weighed an impressive 860 pounds. It included six GM counters, three scintillation counters, two Cerenkov detectors, a magnetometer, micrometeorite detectors, four low-energy ion traps, and the equipment for generating a sodium cloud. As in the case of Luna 1, a bright orange sodium cloud was produced en route.

Several of the scientific instruments were reconfigured from the Luna 1 arrange­ment to take advantage of new scientific information then accumulating. The three – axis fluxgate magnetometer’s dynamic range was adjusted to provide greater measure­ment accuracy as it approached the Moon. Counter sizes and shielding were adjusted. The ion traps were arranged in a different configuration.

Luna 2 provided a wealth of new information on the particles and fields around the Earth, in interplanetary space, and near the Moon.9 One of its most notable achievements was the confirmation and further delineation of the solar wind by the ion traps designed by Konstantin Gringauz. Its magnetometer placed a very low limit on

the strength of the magnetic field near the lunar surface—it is essentially nonexistent. The radiation detectors confirmed the broad structure of the outer radiation belt, as it had been revealed by Pioneer 3. The diversity of detectors added valuable new information about the composition of the outer belt.

On 4 October 1959, the second anniversary of their first Sputnik launch, the Soviets achieved another spectacular first with Luna 3. It took the first pictures of the back side of the Moon.

The Luna 3 craft employed a completely new design. In addition to its primary moon-imaging instruments, it included scientific instruments for measuring cosmic rays, other charged particles, and micrometeorites. Unfortunately, very few results from those auxiliary instruments can be found—the pictures of the Moon’s far side completely dominated the postflight public and scientific releases. The fact that the flight did not contribute substantially to the early radiation belt studies is also likely due to its being launched over the North Pole, so its trajectory carried it north of most of the Earth’s radiation belt structure.

406

With the aggregation of data from Sputniks 2 and 3, Explorers I, III, IV, and 6, Lunas 1 and 2, and Pioneers 1,3, and 4, a quite clear picture of the Earth’s radiation belts was emerging. The collective set of lunar probes during the closing years of the 1950s was especially important in delineating the belts’ overall structure and composition. Figure 14.4 shows the approximate relationship between the trajectories of deep space probes Pioneers 1,3, and 4 and Lunas 1 and 2 and the locations of the two belts.

t has been more than fifty years since the opening of the Space Age with the launching of the first Soviet Sputnik on 4 October 1957.1 That new Earth satellite’s self-assured beep-beep-beep signaled the beginning of a new era. Much has happened since then, including the operation of numerous robotic instruments to probe the new frontier, man’s first tentative venture into Earth orbit, the brash human landing on the Moon, the introduction of new space technologies into our everyday lives and culture, and many new and oftentimes breathtakingly beautiful glimpses of our vast universe.

The years since Sputnik have crept by at a relentless pace. A substantial fraction of the world’s present population has been born since then, and most of them know of those early times only through oral tradition, written history, and artifacts in museums.

I was recently shocked by the realization that we are nearly as far into the Space Age now as we were into the Age of Aviation when the Space Age began. Fifty years before Sputnik (only a few years after the Wright brothers’ first flights in a powered aircraft), the pioneers of aviation were speculating on whether “aeroplanes” might possibly play a useful role in warfare, transportation, and commerce. By the end of those five decades, the effectiveness of aircraft in warfare had been well established in two world wars. Airlines had taken over from trains and ships for much of the long-distance passenger travel. Aircraft were handling a substantial portion of the long-distance shipment of goods. Turboprop engines were rapidly displacing piston engines, and jet engine-driven aircraft were well established in the military services and were beginning to come into commercial service.

During the second half of the twentieth century, spacecraft have been absorbed into our culture in much the same way. We depend on them for many facets of

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our everyday lives, including communications, navigation, position finding, Earth observation, weather and climate observation, tactical and strategic reconnaissance, and many other capacities.

Enough time has elapsed since the beginning of the Space Age to gain a good historical perspective. But it is recent enough that the memories of still-living direct participants can be tapped.

It has been customary in the popular arena to describe entry into space primarily in terms of the manned program. This is perhaps understandable because the venture of humans into any new realm is always far more exciting than the introduction of mere robots.

Nevertheless, instrumented robots did enter space first, and many of the initial technical and operational problems were solved during their development and use. Fortunately, the voices of enthusiastic and dedicated scientists, reinforced by a some­times sporadic popular interest, ensured that the first flights of space-capable launchers were put to useful purposes for research rather than being used simply to prove the technology or for military purposes. This resulted in an immensely imaginative and productive program of scientific discovery.

This tale’s focus on the research program at the University of Iowa’s Department of Physics and Astronomy is not meant to minimize the work of other groups. It does reflect the fact, however, that the Iowa department, under Van Allen’s guidance, did provide outstanding leadership in the new branch of research.

The story may be of special interest from two points of view. First, it describes the experiences of a fledgling scientist-engineer in a uniquely exciting period of initial discovery, vigorous growth, and historical significance in a new scientific arena. Second, it uses many historical materials dealing with the details of the development, launch, and use of the early Explorer satellite instruments that have never been published and do not exist elsewhere.

By extreme good fortune—by being in just the right place at the right time with the appropriate background—I was able to participate actively in the opening of this new era. As I completed my undergraduate work and was looking forward to my graduate studies, I became increasingly aware of the significance of the time. In addition to my already established custom of recording work-related activities in laboratory notebooks, I started noting some of my thoughts and experiences in personal journals. Later, as more of my time was spent in management, I began a series of office journals. Much of the material for this book was derived from those three sources.

INTRODUCTION

he International Geophysical Year (IGY) was an epical scientific event. Through­out the community of geophysical researchers, it provided an infusion of funds and an integrating mechanism for hundreds of individual efforts that were made pos­sible by the rapidly evolving technologies of the time. The various coordination and sharing arrangements that were established for the IGY facilitated the interchange of data and information at a level far beyond that which would have occurred otherwise, and many of those arrangements have continued to the present day.

IGY inception and early planning

This IGY was not the first comparable international effort, although the scale of the new endeavor went far beyond that of previous ones. By the late nineteenth century, there had been a growing realization that the need for observations was global in nature, far beyond territorial boundaries, the intellectual resources of individuals, and even entire countries. This realization, coupled with the newly evolving technologies, was pushing the frontiers of human exploration over more and more of the Earth’s surface.

As a part of that expanding vision, two large-scale international efforts were mounted to apply the combined resources of the world’s leading scientists to exam­ine broad geophysical questions. The First International Polar Year, in 1882-1883, involved a collaboration of scientists to examine the geophysics of the Polar Regions, with concentration on the Arctic. That program included the establishment of a number of meteorological, magnetic, and auroral stations and their operation for about a year.

The Second International Polar Year was conducted during 1932-1933, the golden jubilee of the first. It repeated the earlier endeavor but extended its scope by adding ionospheric observations and by including a substantial component in the Antarctic.

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Those two collaborations provided some of the inspiration, and served as a model, for the International Geophysical Year—1957-1958. That third endeavor, marking the silver jubilee of the Second Polar Year, took place during the period 1 July 1957 through 31 December 1958.

Much has been published over the years to document the planning and achievements of the IGY.1,2’3’4’5’6 Thus, only a brief summary is provided here.

An informal and largely spontaneous dinner party at the Van Allen home in 1950 served as the springboard for the IGY. Van Allen and his family were living at that time in a rented house at 1105 Meurilee Lane, Silver Spring, Maryland, located just off Dennis Avenue near its intersection with Sligo Creek Parkway. This was just a 10 minute drive from Van Allen’s laboratory in downtown Silver Spring.

In addition to hosts James and Abigail (Abbie) Van Allen, that dinner party included Lloyd V. Berkner, Sydney Chapman, J. Wally Joyce, S. Fred Singer, Merle A. Tuve, and E. Harry Vestine. The story of that momentous dinner is best told in Van Allen’s own words:

Vestine [Harry Vestine, who had originally urged Van Allen to make the electrojet search] was delighted with our equatorial electrojet results, as was [Sydney] Chapman who was visiting the United States in early April 1950. On April 5, they visited APL in order to learn about the results at first hand. Chapman expressed an interest in getting together with us and with Lloyd Berkner and Wally Joyce for further discussions. I immediately called my wife to confirm a previously tentative plan that she would have the group for dinner at our home. During the day, she cleaned the house, prepared a splendid dinner, and managed to feed our two young daughters and tuck them into bed as the guests arrived.

The occasion turned out to be one of the most felicitous and inspiring that I have ever experienced. Berkner was one of the leading experts on ionospheric physics and telecommu­nications at that time, had been a member of the scientific staff of the first Byrd Antarctic Expedition in 1928-1930, and had extensive experience in international cooperation in sci­ence while a member of the U. S. State Department. Joyce was a distinguished geomagnetician who had published the well-known Manual of Geophysical Prospecting with the Magnetome­ter in 1937 and was, as I recall, on the staff of the National Research Council at this time.

The dinner conversation ranged widely over geophysics and especially geomagnetism and ionospheric physics. Following dinner, as we were all sipping brandy in the living room, Berkner turned to Chapman and said, “Sydney, don’t you think that it is about time for another international polar year?” Chapman immediately embraced the suggestion, remarking that he had been thinking along the same lines himself. The conversation was then directed to the scope of the enterprise and to practical considerations of how to contact leading individuals in a wide range of international organizations in order to enlist their support. The year 1957-1958, the 25th anniversary of the second polar year and one of anticipated maximum solar activity, was selected. By the close of the evening Chapman, Berkner, and Joyce had agreed on the strategy for proceeding.7

Van Allen’s wife Abbie had a slightly different recollection of the event. In a conversation with Tom Krimigis in July 2007 she related, “… she was talking with Chapman first thing after the dinner and he was waxing eloquently about the Inter­national Polar Year of 1932-33. She suggested, “isn’t it about time to have another one?” to which he responded, “Well, maybe we should.”8

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Planning for this third international endeavor progressed steadily. In May 1950, some 20 scientists, including Chapman (who had by that time left Oxford University for the University of Alaska), further discussed the suggestion at a meeting at the Naval Ordnance Test Station (now Naval Air Weapons Station) near Inyokern, China Lake, California. Further discussions and conceptual planning occurred soon after that at a Conference on the Physics of the Ionosphere, hosted by the Ionospheric Laboratory of Pennsylvania State University.

A formal proposal based on those discussions was conveyed by Berkner and Chapman in July 1950 to the Joint Commission on the Ionosphere, an organization of the International Council of Scientific Unions (ICSU). During the rest of 1950,

1951, and much of 1952, the proposal wended its way through the various ICSU member organizations. In the process, the World Meteorological Organization was added to the list of supporting institutions. The program’s scope was expanded to include synoptic observations of geophysical phenomena over the whole surface of the Earth. At the Amsterdam meeting of the ICSU General Assembly in October

1952, its name was changed to the International Geophysical Year—1957-1958. It soon came to be referred to simply as the IGY.

Sydney Chapman best summarized the scope of the IGY, as finally conceived, in his general foreword to the first volume of the Annals of the IGY:

The main aim is to learn more about the fluid envelope of our planet—the atmosphere and oceans—over all the Earth and at all heights and depths. The atmosphere, especially at its upper levels, is much affected by disturbances on the Sun; hence, this also will be observed more closely and continuously than hitherto. Weather, the ionosphere, the Earth’s magnetism, the polar lights, cosmic rays, glaciers all over the world, the size, and form of the Earth, natural and man-made radioactivity in the air and the seas, earthquake waves in remote places, will be among the subjects studied. These researches demand widespread simultaneous observation.9

The Joint Commission on the Ionosphere recommended that a committee be es­tablished as a focus for the detailed planning. That committee was formally consti­tuted, also at the October 1952 ICSU meeting, as the Comite Speciale de l’Annee Geophysique Internationale (referred to universally as the CSAGI). The CSAGI cen­tral direction was entrusted to a bureau consisting of Sydney Chapman (President), Lloyd Berkner (Vice President), Marcel Nicolet (Secretary-General), Vladimir V Beloussov (Member), and Jean Coulomb (Member).

Four major meetings of the CSAGI, including representation from all participating nations, were held during the period 1953 through 1956 to coordinate overall planning by the many suborganizations and among the national programs. Those pivotal meet­ings tookplace at Brussels on 30 June-3 July 1953, Rome on 30 September-4 October 1954, Brussels on 8-14 September 1955, and Barcelona on 10-15 September 1956.10

During that early planning period, a series of Antarctic, Arctic, Regional, and Discipline Conferences were also held to serve as forums for integrating various

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components of the program. The Antarctic and Arctic conferences concentrated on the overall programs for those two regions, whereas the Regional conferences addressed the Western Hemisphere, Eastern Europe, Eurasia, Africa (south of the Sahara), and the Western Pacific.

The CSAGI established 14 Discipline Groups to plan many of the details.11

Responding to the invitation from the first CSAGI conference in July 1953 to countries of the world to join in the endeavor, the U. S. National Academy of Sciences, acting through its National Research Council, quickly established a U. S. National Committee for the IGY, with Joseph Kaplan as its chairman and Hugh Odishaw as its executive director. That committee served as the focal point throughout the duration of the program for all U. S. IGY planning and operational efforts.

Many other countries responded quickly to the invitation and set up their own mechanisms for coordinating their internal contributions. A key player, the Union of Soviet Socialist Republics (USSR), was slow in reporting its commitment to the IGY, but by the spring of 1955, it had also done so.

he announcement of the launch of Sputnik 1 by the Soviets (Figure 6.1), like a bolt of lightning, instantly changed the complexion of the space program. In many ways, it changed from a collaborative international scientific research program to a race to demonstrate technical superiority during the cold war. It is certainly true that scientists successfully maintained a strong scientific content throughout the early history of the Space Age. But the surprising demonstration of the superiority of Soviet rocket capabilities alarmed everyone in the United States, from military planners to the general public, and precipitated a huge effort to catch up.

Early indications of Soviet intentions

The Sputnik 1 launch should not have come as such a surprise. There were many hints before October 1957 that the Soviet Sputnik would be appearing in our sky. Many of those were missed, ignored, or downplayed by all but the most astute observers. With the supreme confidence of U. S. satellite planners, accompanied by growing public interest resulting from the open publicity surrounding the Vanguard program, and with the Soviet program lurking behind its curtain of secrecy, we were blinded to the growing possibility that the Soviets might be able to enter space before us.1

A substantial body of USSR books, scientific and technical papers, newspaper and journal articles, and items in the popular science magazines carried such hints between the early 1950s and 1957. They provided ample evidence of a growing interest in the subject within the Soviet political, scientific, and public arenas. They covered a wide range of topics, ranging all the way from fanciful dreams and speculations to highly detailed descriptions of equipment, studies of weightlessness, and development of

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flight procedures for cosmic exploration. Many of those articles included interviews with widely respected scientists and engineers.

There were other specific indications of a Soviet intent to enter space. As early as November 1953, A. N. Nesmeyanov, then president of the USSR Academy of Sci­ences, told the World Peace Council in Vienna, “Science has reached a state when it is feasible to send a stratoplane to the Moon, to create an artificial satellite of the Earth.”2

On 16 April 1955, six months after the International Union of Geodesy and Geo­physics passed its resolution that a satellite program be added to the International Geophysical Year (IGY) program, the Moscow newspaper Vechernyaya Moskva re­ported that the Soviet Union planned to launch such a spacecraft. The article went on to tell of concrete actions toward that end, including the creation of an Interde­partmental Commission on Interplanetary Communication, chaired by Academician Leonid I. Sedov and reporting to the Academy of Sciences. Membership on that com­mission included a number of preeminent Soviet scientists. One of the commission’s explicitly named tasks was to launch a scientific Earth satellite to study the effects of weightlessness and of ultraviolet and X-rays from the Sun and stars and to observe ice floes and clouds. Moscow radio reported that a team of scientists had been formed to build the satellite.

On 30 July 1955, the day following President Eisenhower’s announcement of the U. S. plan to launch a satellite as part of its contribution to the IGY, the Kremlin tentatively revealed that the USSR planned to launch satellites during the IGY.

CHAPTER 6 • SPUTNIK! 161

Sedov, heading the Soviet delegation to the Sixth Congress of the International Astronautical Federation in Copenhagen in October 1955, repeated the idea at a press conference that they, too, might be in the satellite game. Choosing his words carefully, he said:

From a technical point of view, it is possible to create a satellite of larger dimensions than that reported in the newspapers, which we had the opportunity of scanning today. The realization of the Soviet project can be expected in the comparatively near future. I won’t take it upon myself to name the date more precisely.3

Despite the press articles and Sedov’s statement, the USSR made no official de­cision on launching an IGY satellite until early 1956. It was then that the USSR Academy of Sciences quietly made an internal commitment to launch an IGY satel­lite within two years, and authorization for its development was made in the form of a decree of the Soviet Council of Ministers on 30 January 1956.

It turned out that that decision was not immediately followed by specific actions to meet the challenge. As the year progressed, progress was lagging, in the opinion of the chief USSR rocket designer, Sergei Pavlovich Korolev, and his allies. One of those associates, Mstislav Keldysh, appealed to the Soviet Academy of Sciences on 14 September 1956, only a year before the Sputnik 1 launch, for more vigorous action. During his presentation, Keldysh stated that they were considering “placing a live organism in the satellite—a dog.” He proceeded beyond that to tantalize them with visions of a flight to the Moon to take pictures of its dark side. His final remark to them was to urge, “It would be good if the Presidium were to turn the serious attention of all its institutions to the necessity of doing this work on time. . . . We all want our satellite to fly earlier than the Americans.”4 In spite of his appeal, the USSR satellite development continued to lag.

There continued to be external signs of the Soviet commitment. In September 1956, Ivan P. Bardin very clearly advised the attendees of the Fourth IGY COSPAR meeting in Barcelona, Spain, that the Soviet Union “intends to launch a satellite by means of which measurements of atmospheric pressure and temperature, as well as observations of cosmic rays, micrometeorites, the geomagnetic field and solar radiation will be conducted. The preparations for launching the satellite are presently being made.”5

By November, the Soviet plans were finally taking tangible form as a duo of satellite designs. Their pride and joy, the one intended to be launched first as their primary contribution for the IGY, weighed in at almost a ton and a half. It was loaded with an assortment of scientific instruments, including, among others, a magnetome­ter, photomultipliers, a mass spectrometer, ion traps, and photon and cosmic ray detectors.

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A second satellite would be very simple—a 184 pound sphere carrying a pair of radio transmitters radiating at frequencies that would make it easy for radio amateurs and anyone else with a simple receiver to receive its signals.

Because of the slowness in getting the program up to full speed, and difficulties in getting all of the flight hardware to operate properly, the launching order was ultimately reversed. The second design became the first Sputnik. A new satellite design with the dog Laika was hurriedly prepared and launched as Sputnik 2 on 3 November 1957. The fully instrumented satellite, after a first launch failure on 27 April 1958, was finally launched on 15 May 1958 as Sputnik 3.

The decision to choose the simple 184 pound satellite for first launch was made only because of the Soviets’ intense desire to beat the United States into space. In a much later interview, Gyorgi Grechko, an engineer who worked on the early USSR satellite program, stated:

But, these devices [referring to the instruments for what became Sputnik 3] were not reliable enough, so the scientists who created them asked us to delay the launch month by month.

We thought that if we postponed and postponed we would be second to the U. S. in the space race, so we made the simplest satellite, called just that—Prosteishiy Sputnik, or “PS.” We made it in one month, with only one reason, to be first in space.6

It appears that the Soviet decision to launch the simple version had already been made by the time of a meeting at the U. S. National Academy of Sciences in June 1957. At that meeting, the Soviet Bardin provided a document to Lloyd Berkner, the Comite Speciale de l’Annee Geophysique Internationale (CSAGI) reporter on rockets and satellites, titled USSR Rocket and Earth Satellite Program for the IGY. In the informal discussions outside the meetings, the Soviets talked quite openly of their plans, contrary to later popular claims.7

Within a month of that meeting, Radio, a Russian amateur radio magazine, included two articles giving a reasonably comprehensive description of that satellite’s intended orbit. It went on to tell how its approach could be predicted by receiving stations anywhere along its path, and how its 20 and 40 MHz signals could be received. They went so far as to include instructions for building shortwave radio receivers to pick up the signals, plus a direction-finding attachment for locating the satellite.

Those articles appear not to have entered the consciousness of U. S. scientists and officials until they were introduced by the Soviet attendees at the CSAGI Conference on Rockets and Satellites during the week of the first Sputnik launch. The primary response to that information at the conference was shock and irritation that the Soviets had departed from the agreed-upon frequencies for transmission. It was not interpreted as an indication that the launch was hard upon us.

Development of a suitable launching rocket was the key to orbiting an Earth satellite. The U. S. planners decided upon the development of a new launch vehicle derived

CHAPTER 6 • SPUTNIK! 163

from technology developed for nonmilitary scientific research. There were a number of reasons for that. One was the desire to keep the U. S. satellite program distanced as much as possible from any signs of military involvement. The more complete story of that decision is related in Chapter 7.

The Soviets had no such compunction. In those days, practically no significant high-technology activity was conducted within the Soviet Union that did not have either military or propaganda implications. They were nearing completion of the development of their first Intercontinental Ballistic Missile (ICBM), the R-7 (SS-6 Sapwood), by a team under the leadership of Sergei Korolev. On 15 May 1957, the first R-7 test launch resulted in an explosion upon ignition. Four additional attempts during the summer also failed. Finally, on 21 August 1957, an R-7 rocket flew 4000 miles over Siberia, landing in the Pacific Ocean near the Kamchatka Peninsula. After a second successful launch, Pravda on 27 August announced to the world that successful tests of an ICBM had been carried out.

It was after that success that Soviet premier Nikita Khrushchev finally yielded to arguments by Korolev and others and gave his approval for the launch of the satellite that had been under development for such a long time. On the centennial of Tsiolkovsky’s birth, 17 September, the Soviet government promised the world that a satellite would soon be launched.

Although the significance of the Pravda announcement in terms of the Soviet Union’s ability to deliver nuclear weapons to any point on the Earth was clearly rec­ognized, there was no expectation in the West that that rocket’s first major assignment would be to loft an instrumented payload into Earth orbit only a few weeks later. U. S. scientists and engineers remained supremely confident that they would launch a satellite into Earth orbit long before the Soviet promise materialized.

In addition, the satellite design had to be completed and built. For the 18 days imme­diately following the Sputnik launch, I was outside the circle of frenzied discussions, negotiations, and design work mentioned above. That situation changed dramatically on Tuesday, 22 October, when I received a telephone call from JPL’s Eberhardt Rechtin. Following up on our discussion in May of matching an abbreviated version of our cosmic ray package to their Microlock system, he briefly outlined their evolving plans and arranged to visit us the following day.

The JPL visitors joined us in Van Allen’s conference room at 4:00 on Wednesday afternoon. Eb happened to be too ill to travel on that day, so Henry Richter came in his place, accompanied by Walter (Walt) J. Downhower. The Iowa attendees at the beginning of the meeting were Ernie Ray, Frank McDonald, Kinsey Anderson, and me (Van Allen was in the South Pacific). Robert (Bob) Parent, from Vern Suomi’s group at the University of Wisconsin, was on campus for a different meeting that morning, and he joined us.

To open the meeting, Henry Richter stated that Eb Rechtin would be visiting the secretary of the Department of Defense two days hence to offer their services, and they wanted to be able to present specific information on scientific instruments to be carried. After that brief introduction, the other Iowa attendees left, and the JPL visitors and I got down to business. They outlined the overall concept of their satellite and the physical environment to be endured by the instruments. We developed a plan for the integration of our instrument that would meet the combined objectives of ABMA, JPL, and the University of Iowa. Their key objective was to place a useful satellite in orbit as quickly as possible. Our primary objective at Iowa remained as before—to conduct the geographically broad survey of cosmic ray intensity that Van Allen had originally proposed.

The discussion quickly led to an understanding that two packages would be launched. The abbreviated package for an initial rush effort would include the basic cosmic ray instrument that we had been discussing at ABMA. That would be followed

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by a second launch of our complete cosmic ray package, essentially as it had been designed for Vanguard.

Several other instruments were being considered for inclusion—thermistors to record temperatures at several places in the satellite and an abbreviated version of Vern Suomi’s solar radiation balance instrument from the University of Wisconsin. Following the meeting, however, after Parent had returned to Madison and briefed Suomi, Suomi stated that it would be difficult or impossible to achieve their scientific objectives with an abbreviated package. Since their full instrument with its internal storage could not be accommodated on either flight, further consideration of their experiment was dropped in favor of relatively simple micrometeorite instruments being developed for Vanguard by Edward (Ed) Manring and Maurice Dubin at the Air Force Cambridge Research Center (AFCRC) near Boston.

It was only later that I realized that I had been drawn, unknowingly, into a major institutional power play. As detailed earlier, we had been working since early in 1957 with Ernst Stuhlinger, Josef Boehm, and their staffs at ABMA on their design for a Jupiter C satellite. Although those discussions included JPL engineers, our understanding was that their participation was for the sole purpose of integrating their Microlock system into the ABMA satellite. It remained our full expectation, as well as that of ABMA’s von Braun, Stuhlinger, Boehm, and their staffs, even until early November, that ABMA would have the lead in developing the satellite, including integrating our instrument.

But Pickering and his staff at JPL had their eyes set upon the satellite task. They believed that the payload logically fit within JPL’s mission, as their organization was shifting away from missile development toward high-technology electronics.

So it was the JPL engineers, instead of ABMA staff members, who visited us on 23 October. As my working relationship with JPL progressed over the next few days, I became increasingly troubled that the ABMA engineers were not participating in our discussions. I mentioned that to Pickering during a conversation on 5 November, but he assured me that his staff were working closely with von Braun’s people, and that it was fully appropriate that I continue to work with the JPL staff. I accepted his assurance.

As I learned later, at the time of that conversation, the ABMA people were com­pletely unaware of the JPL aspirations and separate satellite development effort, even though it had been under way for most of a year. They did not learn of that until 9 November 1957, the day after the directive was issued for the Army to proceed with the Jupiter C satellite program.

On that date, General Medaris held a meeting at Huntsville of ABMA, JPL, and Army personnel to clarify the assignment of roles and responsibilities. It was at that time that Pickering made his move. He asked Medaris for a brief private discussion

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I before the meeting, where he convinced the general that the satellite development role should be assigned to JPL.

Pickering went into that premeeting discussion armed with a number of argu­ments. The JPL work on communications, as exemplified by the Microlock devel­opment, was a strong factor. Furthermore, Pickering believed that they had earned the satellite role through their work with ABMA on Orbiter, Jupiter C, the RTV, and, especially, their efforts during the previous two years in helping to keep the Army satellite possibility alive. He must also have pointed out that greater efficiency and probability of success would result from having the entire upper stage endeavor, including the satellite, located at a single institution rather than to have the rocket cluster/satellite/tracking/telemetry interfaces spread between the two organizations.

Pickering undoubtedly revealed during that private premeeting discussion that JPL had been developing their own satellite and that they were much further along in its development than the ABMA staff. Their production of actual prototype hardware, complete except for the scientific instruments, attested to that fact. I suspect that the final arrow in Pickering’s quiver was the revelation that he had already arranged with me at the University of Iowa to shift our instrument from the Vanguard to the JPL satellite effort.

As author Clayton R. Koppes described the premeeting discussion in 1982:

Just prior to the meeting at which the roles would be assigned, Pickering asked Medaris for a few minutes alone. He argued that JPL should build the satellite. The general probably felt the laboratory could handle the electronics work better than Redstone, and he wanted to keep JPL actively in the Army’s orbit. Von Braun’s jaw dropped when Medaris and Pickering walked into the meeting and informed him of the decision, but the collaboration proved fruitful, and there was more than enough work for both teams. The quarter of an hour Pickering spent with Medaris was momentous. If Redstone had built the Explorer I satellite, it would have had a lock on both the missile [booster] and the satellite. JPL would have been relegated to a minor supporting role, chiefly in its [upper stages and] tracking network, from which it would have been highly unlikely to develop into a major space laboratory. Electronics, which had begun shouldering propulsion aside as the laboratory’s dominant activity during the Corporal weaponization, opened a window to space for JPL.8

In 1986, Pickering recalled that particular event in the following terms:

Medaris had a big meeting on 9 November with about twenty people, including Stewart, Froehlich, and myself. At that meeting, he announced that JPL would be involved [with the satellite design]. I think that came as quite a shock to the Germans. . . we could sense the reaction. But we worked very well together, right up to the launching.9

Additional accounts appeared. Author William E. Burrows described the event and its implications in 1998 in the following way:

Having gotten a green light on the launcher, von Braun and his colleagues assumed that they would get to develop the satellite as well. But they were wrong. Pickering, the chief of the Jet Propulsion Laboratory and a tough New Zealander who was educated at Caltech, believed

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that given the lab’s involvement with Project Orbiter from the start, it had every right to continue participating in the push to reach space. He therefore convinced Medaris to award the satellite contract to JPL. The general undoubtedly believed that JPL, which by then had solid experience in both electronics and rocketry, could handle the assignment better than his own agency.

Whatever Medaris’ motive, though, his decision would prove to be a momentous one. By allowing JPL to design and build what would turn out to be America’s first spacecraft, he unknowingly played into the hands of a man who had already quietly decided that JPL needed to abandon work on tactical missiles and aim higher. Pickering wanted to build machines that would explore the solar system. As a university [administered] laboratory, he would explain years later, “It was quite clear to us that our future lay on the space program,” not in weapons work, which offered little intellectual challenge.10

I continue to be disturbed by the fact that I had been carried into JPL’s private satellite development effort well before ABMA was aware that JPL was seeking the satellite-building role. I believed that I was still operating within the ABMA-led collaborative satellite-building effort. If I had that period to live over, I would certainly call Stuhlinger to discuss the institutional ramifications. Although that would probably not have changed the outcome, it would have made the process more open.

Thus, in retrospect, during the period immediately following the Sputnik 1 launch, three possibilities existed for us at Iowa. First, we could have remained with the Vanguard program by rejecting the Army proposal altogether. Second, we could have continued with the ABMA-led planning for the satellite. Finally, we could have accepted the JPL offer. From the vantage point of later developments, the JPL alternative that we accepted was by far the best one. Had we remained with Vanguard, we would have had only one launch opportunity, as the small number of launch vehicles being procured for that program was fully subscribed for the vehicle-testing program and the launching of the scientific instruments that were being developed. As events unfolded, being second in the Vanguard experiment queue, our instrument would probably not have had a launch attempt until sometime in 1959. And history shows that the probability of a successful launch would have been small. The overall probability that we would have discovered the radiation belts ahead of the Soviets is essentially zero.

The second alternative would have been equally disappointing. The ABMA satellite plan included only a single satellite design—the highly truncated one. Although that might well have been successfully launched, we would still have had to depend on the Vanguard program for launching the full instrument with its onboard storage. That would very possibly not have succeeded, as speculated above.

The JPL promise of two launches, one quick one with the truncated instrument and a second one with our full instrument, was tremendously attractive. The decision to go with the JPL satellite program was felicitous—ABMA and JPL made good

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 221

on their promise, including preparing and launching a third launch vehicle after the failed attempt to launch the complete instrument as Explorer II.

Once the decision was made for JPL to take the lead on the satellite, the arrangement worked well. Throughout, Von Braun insisted that the ABMA primary interest was in getting a satellite into orbit, rather than squabbling over roles. On one occasion, when he and some of his senior staff were flying to California in the ABMA Gulfstream for a meeting with the JPL staff, a discussion broke out about a particular question of roles. The staff wanted von Braun to insist on ABMA responsibility for an activity that JPL also wanted. Von Braun would have none of that. His response to them was to restate his general objective and to threaten the staff that, if they wanted to make an issue of the roles question, he would have the plane turn around and fly back to Huntsville. They continued on to Pasadena.11

To return to the chain of events, Richter and Downhower proceeded from our meeting in Iowa City to Washington, where they joined other JPL members on Thursday for a discussion with a bevy of Army and Navy officers at the Pentagon. The membership of that JPL contingent is a little unclear but probably included either Bill Pickering or Eb Rechtin, plus Jack Froehlich, Al Hibbs, Richter, and Downhower, and perhaps Homer Stewart. Rechtin met with Army Secretary Wilber M. Brucker and Defense Department missile coordinator William A. Holaday on Friday to present their Deal plan. On the following Monday, 28 October, Brucker tentatively agreed with the two-satellite Army/JPL approach. Late that afternoon, Rechtin informed me of that agreement, emphasizing that final approval would have to come from the secretary of defense.

It was during that conversation that Rechtin asked if I had the full authority to shift our experiment from Vanguard to the Army program. That question startled me. I had proceeded with full confidence that Van Allen would be enthusiastically in favor of the change if he had been present. After all, he had long viewed the Army’s Redstone rocket as an attractive launch vehicle. The two of us had made a substantial effort to design our Vanguard instrument package so that it could fit in either the Vanguard or the Jupiter C configuration. The satellite instrument that he and I had worked out with Ernst Stuhlinger and his people during the preceding spring and summer was identical in concept with that now being proposed for the first Army launch. And Rechtin had assured me that our full package would be flown on a second launch.

However, when faced directly with that query, I realized that I, a graduate student working on my master’s thesis on what was actually Van Allen’s proposal and project, did not really have the authority to make such a fundamental decision. I had to reply

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to Eb that final approval for Iowa’s program change would have to come from Van Allen and offered to find a way to reach him.

The next morning, I contacted Mr. Sedwick in Commander Hearn’s office at the Naval Research Laboratory (NRL). His was the office responsible for coordinating the USS Glacier expedition to the South Pacific. He told me that unclassified mes­sages could be given for transmission to the nearest Naval Communication Center through Western Union, or to the commandant of the nearest Naval District. Clas­sified messages had to be hand carried to either the nearest Naval Communication Center or other military center. I called Eb Rechtin at JPL to convey that information at 11:00.

A little later in the day, Henry Richter called to tell me that the USS Glacier would not be arriving in New Zealand until 10 November and that they were attempting to reach Van Allen on shipboard.

During that discussion, Richter told me that they had received a copy of the letter carrying the army secretary’s approval of the program. With that, and anticipating Van Allen’s favorable response, I proceeded with my planning.

The following day, Wednesday, 30 October, Richard Porter, chairman of the U. S. Technical Panel on the Earth Satellite Program (TPESP), informed me that he had relayed the proposal for flying our cosmic ray instrument, plus the temperature­measuring and micrometeorite instruments, to the U. S. National Committee for the International Geophysical Year (IGY), and that the committee had approved. He further stated that he had discussed the change with Homer Newell, overall head of the Vanguard project at NRL, and that he had not raised any objection. Porter told me that a meeting of the TPESP was scheduled for 6 November and that he would relay our requirement for additional University of Iowa funding for the new work.

I was alarmed at one point during that conversation. Porter seemed to be under the impression that there would be only one flight if the first launch attempt succeeded. He heightened my concern by urging that we prepare our complete package for the first flight “if at all possible.” That was not the agreement I had with the JPL people. When I talked with Henry Richter the next morning, I voiced my concern about Porter’s comments, and reemphasized that the complete package with onboard storage was essential for at least one flight. Henry promised to check into the matter, and later reaffirmed the plan for the multiple launches.

Henry also told me during that conversation that JPL had received the first reply from Van Allen but that it was inconclusive. Because of the project’s secret classi­fication, many of the details could not be mentioned in unencrypted messages. To avoid the complications of handling classified messages, JPL had decided to obtain

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 223

his approval through clear channels. The second terse message that Pickering sent to Van Allen on 30 October read simply:

To Dr. Van Allen. Would you approve transfer of your experiment to us with two copies in spring? Please advise immediately. Signed: Pickering.12

In the absence of information about the recent negotiations and decisions being made in the United States, even with his full knowledge of the earlier Jupiter C planning for our instrument, it was impossible for Van to understand what was being asked. He replied on 31 October:

Dr. W. H. Pickering. Unable to interpret your word transfer due ignorance recent devel­opments. Our apparatus for original vehicle nearly finished. Delighted prepare three sets non-storage type for JPL program. Signed: Van Allen.13

That message implies that Van Allen was still thinking in terms of the earlier work with the ABMA personnel, and that we would still be depending on Vanguard for the full instrument package. Pickering responded with a message that reached Van Allen on 2 November:

Present planning suggests [flying] most of existing equipment but transferring responsibility to us instead of carrying two programs. First experiment would be continuous. Second would be storage type. Suggest you phone me on arrival in New Zealand.14

The next day we all received another huge surprise—the launch of Sputnik 2 by the Soviets! Whereas we had been startled in October by the large weight and size of their Sputnik 1, we were dumbfounded by the size and sophistication of Sputnik 2. Our Vanguard satellites were expected to weigh only 23 pounds. Sputnik 1 had weighed 184 pounds. Sputnik 2 weighed an unbelievable 1121 pounds! Not only that, but it carried a live animal, the dog Laika, in addition to its array of scientific instruments. Even though it was revealed later that no provisions had been made for recovering the dog, and that she died of heat exhaustion after about seven hours in orbit, the feat represented a huge coup by the Soviets.

No longer could anyone assert that Sputnik 1 had been the lucky result of a short­term crash effort. It was obvious that the Soviets were very serious about the space business. The workers (and Khrushchev, immediately after the Sputnik 1 launch) clearly recognized the impact of what had now become a race to capture the attention of the whole world and were intent on demonstrating and exploiting their scientific and technological prowess. Even more profoundly, inclusion of the dog in Sputnik 2 suggested their strong interest in manned flight.

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The pressures for an early American satellite mounted!

When the USS Glacier finally arrived in Port Lyttleton, New Zealand, on 10 Novem­ber, an additional message from Pickering awaited Van Allen:

Urgently need your approval on proposed change of Ludwig experiment. Porter committee has given their approval to proposal to change experiment to JPL and to modify experiments as agreed upon between Ludwig and JPL.15

Still somewhat uneasy about his lack of solid information, Van Allen addressed a commercial cable to me at Iowa City on 13 November, asking:

Question: Is Pickering plan for our experiment agreeable with you: Please cable answer IGY rep Christchurch.16

Ernie Ray immediately answered the cable on my behalf:

After high-level approval and obvious rearrangement of old program, George left town for extended stay. George quite happy Pickering plans. Hope you say yes.17

With that reassurance, Van Allen immediately wired Pickering:

Approve transfer our experiment accordance JPL plan.18

Thus, on 14 November, only six days after Department of Defense formal approval of the Army’s satellite plan, Van Allen provided his final approval, and we were free to put the plan into effect.

Van told me some time later that his hesitancy in agreeing to the telegram from JPL was to some extent due to his concern that they might be trying to take over the entire experiment, including the scientific analysis.19 Recently, he indi­cated that he was not as worried as he might have been, because of his belief in Pickering’s innate honesty. That confidence had developed during the many years that the two of them had worked together. Still, Van was much relieved to receive Ernie’s message. [2]

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 225

Therefore, I accepted the JPL employment offer as the most expeditious way to proceed. During the rest of that frantic week, I had a number of conversations with Henry Richter, and with the JPL Personnel Office, to arrange for my employment. I was hired as an employee of the California Institute of Technology, working at JPL, with a title of research engineer, effective 18 November 1957, and at a starting salary of $700 per month.

Van and I have looked back on that decision on several occasions and agree in retrospect that it would have been much better if I had remained on the University of Iowa payroll. I would have been received at JPL more clearly as a senior colleague, rather than as a junior member of their own technical staff. As a practical matter, that turned out not to be a serious problem, as I could work around any issues by calling Van Allen and letting him work them out with Pickering. However, it did cause me considerable frustration, as the arrangement left me outside some of the project-related activities that would have been helpful.

Returning to the events of late October and early November, we used my pending employment at JPL as the official justification for a rush trip to Pasadena. Although it was carried on the books as a recruiting interview trip, its real purpose was for Deal project planning. In anticipation of Van Allen’s approval of the programmatic shift, I left Iowa City on 1 November, arriving in Pasadena late that evening. The next day, we worked out many of the details of the two payloads and of the ground system needed to track and communicate with them. JPL attendees at that meeting included, at various times, JPL director Pickering, project director Jack Froehlich, Eb Rechtin, and Henry Richter.

The primary result of that meeting was full agreement on the payload and ground station configurations for the two launches.20 The block diagram for Deal I appears here as Figure 8.2. With only minor changes, that configuration was the one eventually flown on Explorer I. A similar diagram was sketched at that time for the more complex Deal II, as described later.

Whereas the Vanguard system had included a single transmitter for tracking and data transmission, two transmitters were planned for both Deal I and Deal II to provide greater redundancy. As an added advantage, the system would employ both the Vanguard Minitrack ground network already being built by NRL, and the new JPL Microlock ground network, thus providing expanded data recovery and additional ground system redundancy.

We envisioned at the 2 November meeting that both the Deal I and II satellites would employ a low-powered transmitter radiating continuously at a frequency of 108.00 MHz, a power level of 0.01 to 0.02 watts, and with a linearly polarized asym­metrical dipole antenna. That system would be included primarily for Microlock tracking and telemetry reception, and secondarily for Minitrack interferometric

tracking. It would be expected to operate for two to three weeks. By the time Deal I was actually launched in January, the power had been fixed at 0.01 watt, and the design operating lifetime had been increased to “two to three months.”

A relatively high powered second transmitter was to be used on Deal I primarily for transmitting the cosmic ray data to the Minitrack ground network and for inter­ferometric tracking by those stations. It was to radiate continuously at a frequency of 108.03 MHz with a power level of 0.1 watt, for two to three weeks. It would use a circularly polarized X-shaped antenna similar in its mode of operation to the antenna that had been designed for Vanguard. Identical cosmic ray data streams were to be transmitted through both the low – and high-power systems.

The second Deal I experiment, conducted by Ed Manring and Maurice Dubin of the AFCRC, was to study micrometeorites. Micrometeorite density was of considerable scientific interest in its own right. Also, since the space environment was largely unknown, there was a desire to see if very small meteorites were dense and heavy enough to represent a hazard to this and future satellites.

The AFCRC instruments employed two detectors. The first, a microphone placed in spring contact with the satellite’s shell, was tuned to respond to micrometeorite impacts of 0.012 grams per centimeter per second and greater. In more precise terms,

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 227

the minimum detectable particle mass would be 5.4 x 10-9 grams (assuming a particle velocity of 40 kilometers per second relative to the satellite). The output of that tuned amplifier, scaled by a factor of four, was transmitted via channel 3 of the high-power transmitter.

The second micrometeorite detector was a set of 12 parallel-connected grids of very fine wire. Each grid was wound on a flat bobbin so that it completely covered an area of about one square centimeter. If a micrometeorite of size five microns or larger impinged on one of those grids, its wire would be severed, causing an abrupt change in the resistance of the network. That resistance was telemetered via channel 3 of the low-power system.

The art and science of satellite design was in its infancy, and controlling the temperature of the instruments within the satellite shell represented unknown territory. There was a strong motive for verifying the accuracy of the many calculations and physical provisions for temperature control. To obtain that verification, measurements were made of the temperatures of the aft end of the main cylindrical satellite shell and of the transistor in the high-power transmitter (conveyed over channels 1 and 2 of the high-power system), and of the aft end and tip of the satellite’s front cone (over channels 1 and 2 of the low-power system).

At the 2 November meeting, we also tentatively agreed on plans for JPL to prepare three primary Microlock stations, one near the launch site at Patrick Air Force Base (Cape Canaveral, Florida) and two to be located at then unspecified locations, but “perhaps in Hawaii or the Philippines.” Use would be made of NRL’s full Minitrack stations in South Africa and Australia, plus somewhat simplified Minitrack stations in the United States, South America, New Zealand, Nigeria, and Morocco. That initially envisioned network configuration was eventually considerably modified, as described later.

At the end of that Saturday meeting, we agreed to give urgent priority to procuring certain components that might not be available from supplier’s stocks and might have to be manufactured. Other matters, including arrangements for the University of Iowa to provide the flight tape recorders, security, and financial arrangements, were also addressed.

I spent part of the next morning familiarizing myself with the Pasadena area so that I would be prepared to search for a temporary home when I arrived with my family. That Sunday afternoon, I returned to Iowa City.

The next day, I called Pickering with my proposed budget for the additional Iowa work. Our total budget for developing the satellite instrument as part of the Vanguard Project had been $106,375. I estimated that we would need an additional $39,100 if we were to modify the package at Iowa City. That included an additional $2000 for two

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part-time employees for six months, $12,000 for additional equipment and supplies, $8000 for additional travel, and $12,000 for data reduction, which, we realized by then, had not been adequately funded in the original Vanguard budget. I also informed him that, if the work on preparing the instrument were shifted to JPL, the University of Iowa would need only the additional $12,000 for data reduction.

Those funding figures highlight an interesting aspect of the space program at that time. We, on our university campus, and JPL, in Pasadena, operated in entirely differ­ent financial realms. During the preceding seven years, the Iowa Physics Department under Van Allen’s leadership had developed a burgeoning space research laboratory from nearly nothing, on a shoestring budget. We were used to scrounging military surplus sources for resistors, capacitors, screws, and other parts, and to operating with a tiny staff of a few faculty members and graduate students and a handful of part­time students. Improvisation was the byword. The total University of Iowa budget of just over $100,000 for the Vanguard instrument (admittedly not including instrument shop expenses and overhead charges) was laughable by later standards, even within a university environment.

On the other hand, JPL was a major military contractor. By that time, it had a staff of over a thousand and was well versed in the business of developing and testing ultrareliable equipment to meet military standards. They were able to commit hundreds of people to the Deal project. A 20 November 1957 Deal organizational chart lists 26 people in senior supervisory and consultative roles, and about 100 others with major named responsibilities, split almost evenly between rocket preparation, satellite instrumentation, and ground stations and operations. Those individuals were backed by legions of technicians and other supporting staff.

This is by no means a criticism of JPL. We would have been terribly hard-pressed at Iowa to prepare our cosmic ray instrument in time to meet the Deal schedule. In addition, the JPL effort provided a much greater assurance of reliable performance for several reasons. The design of all elements of the configuration was worked over meticulously by the highly skilled and experienced JPL engineers, the testing was thorough, and the combined Microlock and Minitrack tracking and telemetry configuration was far more robust than the Vanguard Minitrack system would have been by itself.

In summary, the move of our instrument construction from Iowa City to Pasadena was the only viable arrangement under the circumstances.

On 6 November, immediately upon my return from Pasadena, my direct participation in the Deal project began in earnest with a long working telephone conversation with Henry Richter. He informed me that they were starting work on our Deal I cosmic ray instrument immediately, that Dean Slaughter and John A. Collins would be working

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 229

with me, and that they were listening in on the line. Those senior engineers in Henry’s New Circuit Elements Group did much of the work in constructing my instruments, testing them, and integrating them into the satellite. They were to become among my closest and most highly regarded associates during my stay at JPL.

Henry’s and my conversation on that day covered some of the preliminary work that they would accomplish before my arrival. As their first priority, they were procuring a supply of the Geiger-Muller (GM) counters. They had already talked to Anton Laboratories, manufacturer of the counters, and the first shipment had been promised for delivery in about a week. His staff were also starting to build a test model of the 700 volt high-voltage supply to power the Geiger counter. Following our discussion, I sent them regulator tubes, transistors, and a transformer so they could breadboard the high-voltage power supply according to the design worked out at the U. S. Army Signal Corps Engineering Laboratories. I immediately called George Hunrath there to coordinate their supply of additional parts kits. Having just made another design revision to improve the voltage regulation, they were nearly ready to ship the kits for the flight instruments.

My time from then until I left Iowa City in mid-November was fully consumed by continuing project coordination and in preparing for my family’s move.

Security was a major concern. Whereas the Vanguard project had been conducted openly, the program to tool up the Army’s Jupiter C satellite launch vehicle was shrouded in secrecy. Recurring delays in the Vanguard launch schedule, the public outcry following the successful USSR Sputnik launches, and the strong element of risk in undertaking the Jupiter launch on such a short schedule made the Army leadership gun-shy, and they chose to operate outside the public spotlight.

That was strongly reinforced on 6 December 1957 following the spectacular and highly publicized launch failure ofVanguard Test Vehicle 3 (TV-3). On that memorable day, with the whole world watching on live television, we were expecting to witness the launch of the first U. S. satellite. Instead, the first stage rocket lost thrust after two seconds, the entire vehicle collapsed into a huge fireball, and the still-bleating satellite spilled onto the ground. The press had a field day!

With that grand public humiliation, the Army became absolutely insistent that de­tails of the Deal project be kept under wraps until a successful launch was achieved. General Medaris at Huntsville strove to make the launch preparations look like just another routine Redstone missile test. Even in highly classified cables between Huntsville and JPL, the launch vehicle was referred to simply as Missile 29. Key personnel whose movements might give away the secret moved under elaborate decoy plans. At the Cape, erection of the booster and the upper stages was particularly sen­sitive, as that could be observed from the public beaches. Thus, the upper stages were

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covered with canvas for their predawn move from the assembly area to the launch pad. The working platforms and shelters on the gantry were kept in place around the upper portion of the assembly throughout the prelaunch preparations to screen it from the beach observers.

Medaris warned, “I cannot overemphasize the importance of these decoy plans and the absolute necessity of covering this launching as a normal test of a Redstone missile, and I desire it well understood that the individual who violates these instructions will be handled severely.”21

Parenthetically, I never saw that directive and was not fully aware of the force of those instructions at the time, understanding simply that we were not to talk about the project outside of our close circle of coworkers. I came close to violating security on one occasion. During a trip from Pasadena to the Cape (it was for either the Explorer II or III launch), our plane was diverted from Orlando to Tampa because of weather. JPL arranged for a car to drive us from Tampa to Cocoa Beach. During that long drive, believing that all in the car were JPL employees, I began to talk about the upcoming launch. I was immediately interrupted by one of the occupants and told to be quiet. Apparently, the driver was not an appropriately cleared JPL employee.

Thus, I had to be discreet in preparing for our move to California. All conversations related to the move had to be cloaked in oblique terminology. I was permitted to include only the head of the Physics Department in any detailed discussions. Ernie Ray was the acting department head in Van Allen’s absence, and we worked closely together on the details. I withdrew from my university classes without being able to give my professors or classmates any cogent reason. Likewise, we withdrew Barbara from her kindergarten class. My Dad, by now an avid satellite program enthusiast and publicist, had been interviewing me frequently on his daily radio programs and had otherwise kept his audience fully informed of our progress. Suddenly, I had to cut off his source of information, and he could mention only that my family was making a sudden move to California.

The other media, especially the local newspapers, had been carrying extensive coverage of our instrument development. They, too, were suddenly cut off from further information. I had to cancel all plans for public appearances. Rosalie and I made hasty arrangements to move out of our house for several months without being able to tell our landlady the reason. Fortunately, our neighbors when we lived in married student housing at Finkbine Park, Gene and Charlotte Boley, needed a house until Gene graduated in February. Thus, they stayed in our house for the initial period of our absence.

The Defense Department made a guarded public announcement on Friday, 8 Novem­ber, of the president’s decision to launch a satellite with the Army’s vehicle.

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 231

The formal enabling teletype message reached ABMA the next day. That official go-ahead started the countdown clock. Von Braun had promised that the satellite would be launched within 90 days of approval. Because of scheduling considerations for Cape Canaveral’s downrange facilities, the launch actually had to be planned for 29 January, only 80 days after the approval.

From then on, it was a race against the clock. Work on the instrument repackaging progressed briskly at JPL. I gambled by dispatching some of our household furnishings to Pasadena via moving van on 12 November, two days before receiving Van Allen’s final approval for the program change.

On Sunday, 23 March, I left again for Cape Canaveral to help with the final prepara­tions for the Deal IIb launch. I arrived at Cocoa Beach late that evening and checked into the Coral Sands Motel on the Cocoa Beach strip.

Even then, planning for a future satellite instrument was occupying a significant portion of my attention. On the previous Thursday, during a phone discussion with Van Allen, I indicated that (1) after my trip to the Cape for the launch, I would stop at ABMA for further discussions of the new IGY Heavy Payload (eventually orbited as Explorer 7, as discussed in Chapter 14), (2) I had given the ABMA engineers the power and size requirements for our new instrument, (3) I would be sending him a list of parts to be ordered for its construction, (4) the transmitter power output would

CHAPTER 10 • DEAL II AND EXPLORERS II AND III 281

be about 0.5 watt, (5) we discussed the placement of the GM counter in the payload, and (6) we agreed on a scaling factor of 512 to reduce the counting rate of the GM counter to a value that could be conveyed over the telemetry system.

On Monday, after making my way to the Cape installation, I learned that the JPL engineers had experienced continuing payload problems. Several of the instrument packages interrogated themselves spontaneously—the result of the increased receiver sensitivity built into the flight packages, combined with the complex radio frequency environment in the area. The engineers installed additional filters in the payloads to correct that problem. The data tape recorder in Payload III skipped some of its pulses, and the engineers substituted the recorder from Payload IV. Then a wire from the release solenoid in that recorder broke off, and they replaced the solenoid with the one from the unit they had just removed.

Fortunately, the recorder in Payload II worked perfectly all through the prelaunch testing, and that payload was eventually selected for launching. It continued to operate perfectly on launch day, both for recording and interrogation. In orbit, its operation was flawless throughout the satellite’s entire operating lifetime.

It has always disturbed me that getting the mechanical recording system to operate dependably was such a problem. Today, it would be relatively easy to fabricate a much less troublesome nonmechanical system with solid-state components. But in 1958, we were pushing the state of the art. I believe that the system in Explorer III was as good as I could have made it at the time. I have always realized that a considerable amount of luck was involved in getting the system in Explorer III to operate so well in space.

The launch countdown was a reprise of the Deal IIa launch, except that it progressed with even fewer hitches. The preflight check on the satellite began at 5:12 AM EST on Wednesday, 26 March 1958, with the countdown clock at X – 380 minutes. A low-power system cosmic ray background rate check was begun at 8:09 AM. We made an interrogation check of the onboard recorder at 8:47 AM and a frequency check two minutes later. By that time, the launch countdown had progressed to X – 165 minutes. We made another spot check of the satellite payload at X – 50 minutes. At that time, a hold had been prescheduled to provide time to catch up in case there had been delaying problems. There had not been, so we simply relaxed and waited during that hold.

Van Allen was in the Pentagon again for the launch. While I was listening to the progress of the countdown in the blockhouse, Van was following the same voice comments via a communication circuit between the Cape and Washington. He jotted down the essential content of those comments in his field notebook, which has been

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preserved as part of the collection of Van Allen Papers in the University of Iowa Libraries, Department of Special Collections. They provide an excellent impression of the progress of a typical rocket-launching countdown during that era. The excite­ment of the occasion is evident in the notes, extracted here in slightly abbreviated and paraphrased form. His notes began soon after 11:00 AM, when the count was resumed14:

26 March 1958. 11:05 A. M. EST. Picked up count at X – 50. Surface weather raining, but not to a deleterious extent.

11:30. As scheduled, the count is holding at X – 30.

11:39. [Predicted] values for 24 March are as follows:

Range at Injection: 775 km.

Initial Perigee height: 352 km (219 mi.)

Initial Apogee altitude: 2043 km (1269 mi.)

Time, Liftoff to Cutoff: 152.7 sec.

To Thrust decay: 155.7 sec.

To Separation: 157.7 sec.

To Second Stage: 396-404 sec.

To Third Stage: 404-412 sec.

To Fourth Stage: 412-420 sec.

Time, Liftoff to Injection: 420 sec.

Nominal firing time 12:30.

11:50. The local weather is improving at the Cape.

12:15. The count is X – 17.

All vehicles have left the pad.

12:20. The pad is clear of all personnel.

12:20. Telemetry checks are being made.

X-12 at 12:20 EST.

Holding at X – 10 as of 12:22. The reason for the hold—checking the beat-beat [tracking system] indications.

The count has been resumed at X – 10 as of 12:28 EST.

Cluster spinup has been started.

Range instrumentation has been checked out and no difficulties have been found.

X – 8 at 12:30 EST. The Cluster has reached 350 rpm.

The Cluster is up to programmed speed and the cluster ignition test signal has been checked. X-5 at 12:33 EST.

X – 4 at 12:34 EST.

All instrument panels have been checked out with no trouble.

X-3.

X – 2.

The range is clear at X – 90 seconds.

X – 1 [minute].

– 50 sec.

– 40 sec.

All preparations complete.

– 20 sec.

– 10

Firing command.

At the Cape, I noted that the work to improve the reliability of the satellite command system and onboard tape recorder had paid off, as there were no problems while the upper-stage tub was spinning. I monitored the signals from the Iowa instrument

CHAPTER 10 • DEAL II AND EXPLORERS II AND III package throughout the countdown and gave my OK on instrument performance after cluster spin-up and finally once again just a few minutes before ignition.

Liftoff occurred at about 12:38 PM EST on Wednesday, 26 March 1958, only eight minutes after the originally scheduled time. The rocket disappeared quickly into low cloud cover, and final injection into orbit occurred at about 12:46. As the payload disappeared from radio range, the Doppler shift looked good, signifying a proper velocity in its path away from the Cape.

I was impressed once again by the sense of overwhelming power as the rocket lifted off and accelerated away from us. I was talking on a phone at the time, giving the liftoff details to the NRL receiving station in Hangar S, where they were also tracking it. As soon as ignition occurred, I could no longer hear my own voice at all, even though I was shouting into the phone.

Van Allen’s field notes continue to provide a vivid account of the ascent and injection:

Ignition normal—main stage.

Liftoff.

Exhaust plume looks good.

Tilt program has started.

Beat-beat indications are good.

Acceleration appears normal.

12:39. Following trajectory very closely.

Program and lateral acceleration are good.

Programming of cluster speed proceeding as planned.

Tilting program completed.

First stage cutoff OK.

First stage] launch was normal. Cluster and instrument compartments are now coasting to apex.

During this coasting period, the variable jet nozzles are aiming the upper stages to the pre-calculated angle for injection.

The on board timer is to ignite the second stage at 396 seconds after liftoff.

12:45. All four stages ignited according to all indications.

12:58. Pickering reported Antigua interrogated successfully.

At the Cape, I, too, learned that the down-range Antigua Minitrack station had made a successful interrogation of the onboard tape recorder soon after the final rocket firing. Only a single command transmission was required, a strong signal containing a two second recorder readout was received, and the tape recorder was reset for its first orbit.

A simplified Minitrack station at Johannesburg, South Africa, acquired the low – power signal as the satellite passed overhead, but it was too early to reveal whether or not the satellite had achieved a durable orbit. As in the case of Explorer I, there was a long delay before we could confirm that the payload was in orbit.

The observers at the Pentagon learned that a receiving station at the Naval Or­dinance Test Station near Inyokern, California, received the new satellite’s signal beginning at about 14:34 EST (19:34 UT). I did not have access to that information at the Cape, but I soon learned there that the low-power transmitter signal was received

OPENING SPACE RESEARCH

in quick succession at the Microlock stations at JPL (19:35:05 UT), Earthquake Valley (19:37:33 UT), and Temple City (19:39:55 UT). The Vanguard project’s San Diego Minitrack station also received the signal at about the same time that Earthquake Valley received it.

Such conclusive receipt of the low-power transmitter signal at the completion of the first orbit caused great jubilation. Determining whether the full cosmic ray instrument package was operating properly took more time, however.

Only the Vanguard Minitrack stations had the equipment for commanding the readout of the onboard recorder. The only such station on the West Coast was the San Diego station. They attempted repeatedly near the end of that first orbit to interrogate the recorder but were unable to detect any response. Hearing that, my heart sank, as recovery of the onboard stored data was essential if we were to achieve the full objectives of our experiment.

I remained at the listening post at Cape Canaveral to sweat out the next orbit. For the pass at the end of the second orbit, the Minitrack station at Quito, Ecuador, had the primary data recovery and tracking responsibility. They received the low-power signal and made a series of 10 command transmissions but were unable to detect any response of the high-power system. Our hopes were buoyed a bit, however, by a report that the Lima, Peru, station, marginally within range, might have heard a faint response from the data recorder.

I went from the Cape to Huntsville to discuss the new IGY Heavy Payload. It was not until early afternoon on the 27th, in Huntsville, that I was finally able to get in touch with Jack Mengel in Washington and learned with tremendous relief that some of the subsequent attempts to read the in-flight recorder had produced better results. By that time, receipt of onboard recorder data dumps had been reported from 5 of 12 satellite passes. I was ecstatic!

During the telephone conversation with Van Allen on launch day, in addition to the discussion about the new satellite planning, he asked that I arrange to bring one of the Explorer I spare payloads back to Iowa City for further calibration checks.

Van returned to Iowa City from Washington that evening. During a stop in Chicago, he called Jack Mengel and received the same information that I had received at the Cape, that is, that the Quito interrogation had apparently been received at Lima. On the next day, he received the same news that I was receiving at Huntsville, that is, that 5 of 12 attempts had been successful.

The further history of Explorer III operation is picked up in the next chapter.

Explorer III’s final velocity was higher than the planned value, so that the maximum orbital height (apogee) was quite high. We found, however, that the final stage was pitched up by from four and a half to six degrees from the horizontal when it fired, resulting in a somewhat lower minimum height (perigee) than planned. The initial

CHAPTER 10 • DEAL II AND EXPLORERS II AND III 285

calculations at the NRL Computer Center on Washington’s Pennsylvania Avenue indicated that the perigee height might be as low as 60 miles, which would result in only a two week orbital lifetime before the satellite’s velocity would be slowed by atmospheric drag and it would plunge earthward. By the next day, however, a greater accumulation of tracking data and hard through-the-night work by Joe Siry’s orbital computation team yielded more accurate orbit parameters, including a perigee height of 125 miles and an apogee height of 1735 miles. Based on that new information, the orbital lifetime was projected to be from four to six months, plenty of time for us to conduct our experiment.

Parenthetically, with the higher-than-planned apogee, the satellite turned out to be even more helpful in delineating the anomalous high-intensity radiation than it might have been at the nominal heights.

Explorer III with its attached rocket stage, like Explorer I, spanned 80 inches in total length and six inches in diameter. The total weight placed in orbit was 31.00 pounds, of which 10.83 pounds was the satellite instrument, 7.50 pounds was the shell, and 12.67 pounds was the exhausted final rocket stage.

The initial orbit ranged from 116 miles at perigee to 1739 miles at apogee, with an inclination relative to the Earth’s equator of 33.5 degrees. The initial orbital period was 114.7 minutes. The satellite reentered the Earth’s atmosphere on 28 July 1958.

I was anxious to get to Iowa City following the launch, but, as mentioned above, I had to stop at Huntsville to coordinate our efforts on the new IGY Heavy Payload. Arriving there at midday on Thursday, 27 March, I joined a meeting already in progress. Chaired by Josef Boehm, that meeting dealt with many details of the payload’s mechanical structure and electronic systems. The next day, I met with H. Burke to further discuss electronic circuits, and then again with Boehm on overall project planning. By that time, my notes were frequently referring to the IGY Heavy Payload as the Juno

II project. Further details of that meeting and the follow-up work are described in Chapter 14.15

It was finally possible to leave Huntsville for Iowa City at noon on Friday, but I was frustrated en route by tardy plane departures and missed connections that forced me to remain overnight in Chicago. In a rather foul mood, as I sat waiting at the Chicago airport, I wrote a note that reflected considerable frustration at the situation then facing me, in spite of the exhilaration of the successful launch:

Had a successful visit at Huntsville. But it looks like Juno II will be another crash program. The first two packages (SUI’s part) are to be done by May 1. Looks like I’ll have to rush back to Iowa, or at least to the Iowa payroll. What a life!! I’m getting a little weary of this rat race—after over two years of it. It will be nice to settle down to school for a while, if that ever happens.16

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Since the pressure for me to move ahead quickly with the Juno II circuit design was so intense, my stop in Iowa City was fleeting. Arriving there at mid-morning on Saturday, 29 March, I had several conversations with Van Allen and the others. Although the preliminary indications from the Explorer I data were hugely intriguing, my personal preoccupation during that visit was to brief our team on the results of the Juno II planning meeting.

During spare moments on that trip, I continued writing a paper describing the Explorer I instrument.17 I left Iowa City for my return to Pasadena at about noon on Monday, 31 March.

Endnotes

1 George H. Ludwig, Laboratory Notebook No. 57-6, covering 10 September 1957 to 30 June 1958, p. 33. Undated entry. Also see George H. Ludwig, JPL internal memorandum to Milton Brockman, “To prepare package for spin test,” 25 November 1957.

2 George H. Ludwig, Laboratory Notebook No. 57-6, covering 10 September 1957 to 30 June 1958, p. 51. Entry dated 9 December 1957.

3 Walter K. Victor, Inter-office memorandum to JPL Cognizant Engineers, “Deal II Standard Operating Procedures and Scheduling,” 13 December 1957.

4 George H. Ludwig, letter to James A. Van Allen, 22 January 1958.

5 Ibid.

6 Ludwig, Laboratory Notebook No. 57-6, p. 51. Entry dated 9 December 1957. Also George H. Ludwig, Journal covering 19 September 1956 to 23 August 1960. Entry dated 18 February 1958.

7 Ludwig, Journal covering 19 September 1956 to 23 August 1960. Entry dated 20 February 1958.

8 George H. Ludwig, JPL Travel Report, 20 March 1958.

9 Ludwig, Laboratory Notebook No. 57-6, pp. 96-99. Entries dated 3 and 4 March 1958.

10 George H. Ludwig, Journal covering 19 September 1956 to 23 August 1960. Entry dated 5 March 1958.

11 Richard Witkin, “2D U. S. EXPLORER FIRED, VANISHES; ORBIT IS IN DOUBT,” The New York Times, 6 March 1958.

12 The results of these tests were described in H. R. Buchanan, JPL inter-office memorandum to Walter K. Victor, “Deal II ‘Turn-On’ Receiver Sensitivity Tests,” 14 March 1958.

13 Robert L. Choate, “Calibration Records for the IGY Earth Satellite 1958 Gamma,” JPL Publication No. 126, 27 June 1958.

14 James A. Van Allen, field note pad entry dated 26 March 1958, located in “Papers of James A. Van Allen,” University of Iowa Library Archives, Iowa City, Box 384, folder 2.

15 The meetings during that visit are recorded in George H. Ludwig, Laboratory Notebook No. 58-8, covering 2 to 18 April 1958 and 30 June 1958 to 2 January 1959, pp. 136-137. Entry dated 2 April 1958.

16 George H. Ludwig, Journal covering 19 September 1956 to 23 August 1960. Entry dated 28 March 1958.

17 George H. Ludwig, “Cosmic-Ray Instrumentation in the First U. S. Earth Satellite,” Rev. Sci. Instrum., vol. 30 (AIP, April 1959) pp. 223-229. Reprinted in IGY Satellite Report, no. 13 (Wash., DC: Natl. Acad. Sci., January 1961).

As mentioned earlier, because of the demands of the new IGY Heavy Payload instru­ment development, and so that I could join in the task of processing and analyzing the Explorer I and III data, Van Allen and I agreed that I should return to the Iowa campus as quickly as possible. Adding to the urgency of my return was the grow­ing possibility that an additional project (beyond the IGY Heavy Payload) might be approved and would also have to be conducted on a crash basis. In fact, that project did quickly materialize, culminating in the launch of Explorer IV and the Explorer V launch attempt, as described in Chapter 13.

Upon reaching Pasadena from my Iowa City stopover, I found that Rosalie had everything under control, and two-week-old George was thriving. The week was completely consumed, on the home front, by preparations for our move back to Iowa City and, at the laboratory, on program planning and detailed design work for the Juno II instrument. Rosalie carried most of the burden of preparing the household for the move, closing all of our bank and utility accounts, terminating our house contract, taking Barbara out of school (again), and packing our personal belongings.

My primary occupation during that week was to design the electrical and mechani­cal configuration of our IGY Heavy Payload instrument and to order its GM counters. I also spent time collaborating with other experimenters and engineers on the new project, including Vernon (Vern) Suomi at the University of Wisconsin, Mr. Hanson, who worked for Gerhardt Groetzinger at the Research Institute for Advanced Studies, and H. Burke at Huntsville.

I also completed the steps necessary to terminate my active employment at JPL. Following their suggestion, I remained an inactive and unpaid member of the JPL staff. That was intended to make it easy for me to return there for postgraduation

FIGURE 12.4 The author preparing the spare Explorer I satellite for the move back to Iowa City.

It, along with all University of Iowa laboratory equipment and our personal effects, was loaded into a U-Haul trailer and pulled behind our Mercury for the drive home. The scene is at the rear of our temporary residence on Claremont Street in Pasadena.

employment, if that should be my desire. It gave me a prearranged employment option more than two years before I received my Ph. D. degree. As it developed, I accepted postgraduation employment at the newly forming NASA Goddard Space Flight Center, and the staff arrangement with JPL, for which I was very grateful, was eventually terminated.

My return to Iowa posed an interesting problem. I was going off the JPL payroll, and they had no obligation to pay for my return move. As SUI had had no financial involvement in my original move west in November, and since they were simply resuming my previous employment at Iowa City, they had no legal obligation to help in moving my family and household possessions back. Fortunately, since I was transporting all of our laboratory equipment, parts, supplies, and spare Explorer I and III satellite payloads back to Iowa, Van Allen felt justified in paying for my own direct transportation expenses. He also adjusted my salary for the next few months to help compensate me for flying Rosalie and the three children back.

Rosalie’s return airline flight with Barbara, Sharon, and two-week-old George on Saturday, 5 April, was as uneventful as one might hope under the circumstances, as they were able to take a direct flight from Los Angeles to Cedar Rapids, only 30 miles from Iowa City. My parents picked them up at the airport and delivered them to our Rochester Avenue home.

To keep the expense of the move as low as possible, I rented a U-Haul trailer to transport the laboratory equipment, spare Explorer I and III units (Figure 12.4), and our personal effects. I left Pasadena on Monday, driving our Mercury sedan and the rented trailer via a southern route through Arizona, Texas, the Oklahoma Panhandle, and the new Kansas turnpike to avoid the possibility of lingering harsh winter weather

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in the high Rockies farther north. I arrived in Iowa City on Friday, 11 April, after a very pleasant solo drive. My journal reported of the trip, “No bad weather, beautiful scenery.”

As I drove into Iowa City, events at the cosmic ray laboratory were unfolding at a feverish pace. The IGY was in full swing. Van Allen and our small cluster of students, faculty, and staff were hard at work on an energetic balloon, rocket, rockoon, and satellite IGY research program.

There was great public and scientific excitement about the burgeoning space pro­gram, especially after the national humiliation of losing the distinction of being first in space to the Soviets. Pressures were mounting for capitalizing on the early U. S. successes as quickly as possible with follow-on space programs.

That Saturday, 12 April, Van Allen, McIlwain, and Ray brought me up to date on the current situation. The satellite instruments on both Explorers I and III had been working flawlessly and were providing a growing tide of data. Explorer I had reached the end of its operating life, and its ground station recordings were being converted on a routine basis to strip chart records and columns of numbers. Explorer III was working well, a reasonable rate of successful interrogations was being achieved, and the first data recordings were reaching us. The account of that Saturday meeting, as recorded in my personal journal several days after the fact, contains the following paragraph:

By now a very startling and interesting result has appeared in the data. We have encountered some extremely high counting rates at the higher altitudes, and at perhaps all latitudes within north and south 33 degrees. Present thinking is that they may be due to electron clouds. Counting rates are probably over 4000 per second. This result appears on both Explorers, and there seems to be no doubt as to its existence.33

We decided at that meeting to change our Juno II heavy payload counter configuration to allow us to study the new phenomenon with greater discrimination.

During late March and early April, Van Allen, with active involvement by Carl McIlwain, continued discussions with Wolfgang Panofsky that had begun at the 11­12 March meeting at JPL. A satellite was being considered that would have detectors arranged to make more quantitative measurements, both of the natural radiation that we were observing and of charged particles that might be injected into trapped trajectories by a high-altitude nuclear burst—what came to be known as Project Argus.

A few days before our 12 April get-together, Van Allen conveyed our growing belief in the existence of the high-intensity radiation regions to Panofsky. That was the first revelation of the new discovery to anyone outside our small group of four.

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That letter and its background and implications are discussed further in the next chapter.

Van Allen was sufficiently confident in our conclusions by mid-April that he discussed them with several IGY program officials, namely, Richard Porter, Hugh Odishaw, Homer Newell, and William Pickering.34 Those calls were made, most likely, on Monday, 14 April.

The U. S. National Committee had recently established a policy for the release of scientific information derived from U. S. satellites in the IGY program.35 It provided that all satellite-derived data should be conveyed to the U. S. National Committee in advance of any public release. Odishaw reminded Van Allen of that policy and admonished him to make no public announcement of the new discovery until a formal IGY release could be arranged. The two agreed, during that conversation, on a release date of 1 May.

During the last two years of the 1950s, the space program advanced rapidly, both in terms of the technology and of the science. The growing experience and confidence of the Soviet and American technicians and scientists, combined with the increasing

2. PHOTO-MULTIPLIERS FOR THE

REGISTRATION OF THE CORPUSCULAR RADIATION OF THE SUN

3. SOLAR BATTERIES

4. DEVICE FOR THE REGISTRATION OF PHOTONS IN COSMIC RAYS

FIGURE 14.5 Sputnik 3, with identification of its major features. Weighing nearly 3000 pounds and measuring nearly 12 feet long and 6 feet in diameter, it was gigantic in comparison with early U. S. satellites. (Courtesy of the National Aeronautics and Space Administration.)

weight-carrying capability of U. S. launch vehicles, led quite naturally to spacecraft of increasing size, capability, and complexity.

Some of the spacecraft of that period are referred to as second-generation space­craft, distinguished by the inclusion of multiple primary instruments that made in­creasingly discriminating measurements. In many cases, instruments were comple­mentary in nature, carefully chosen to address specific questions.

Sputnik3 Sputnik 3, discussed earlier in Chapter 12, with its immense weight and array of scientific instruments, was the first of the second-generation spacecraft. A full-blown automatic scientific laboratory, the Soviets originally planned that it would be carried on their first satellite launch attempt. Problems with payload development and the resulting launch postponements led to the preparation and earlier flight of the simpler Sputniks 1 and 2.

This spacecraft was indeed remarkable. Launched on 15 May 1958, it carried, in a single carrier, more instruments than had been planned for the entire U. S. Vanguard program. Illustrated in Figure 14.5, the spacecraft was designed to investigate the pressure and composition of the upper layers of the atmosphere, the concentration of positive ions, the magnitudes of the electric charge of the Sputnik and of the Earth’s electrostatic field, the magnitude and direction of the Earth’s magnetic field,

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the intensity of the Sun’s corpuscular radiation, the composition and variation of primary cosmic radiation, the distribution of the photons and heavy nuclei in cosmic rays, and micrometeors.

Sputnik 3 provided a wealth of new information. Reaching higher latitudes than the earliest U. S. Explorers, it traveled through the lower north cusp of the outer radiation belt. It helped put to rest scientists’ early fears that micrometeorites might be dense enough to seriously impede our ventures into space. Important results related to the geomagnetic field, low-energy ions, and electrons in the far atmosphere and near space and related to cosmic rays were obtained from this mission.10

Explorer 6 Explorer 6 was the second highly successful second-generation space­craft, and the first one by the United States. It was a spheroidal satellite with four solar paddles designed to study a wide range of geophysical and astrophysical phenomena. The arrangement of components within the central cylindrical platform is shown in Figure 14.6.

Whereas the Explorer I, III, and IV and Sputnik 1 and 2 orbits all lay within 1800 miles of the Earth’s surface, and therefore barely edged into the high-intensity radiation belts, the highly eccentric Explorer 6 orbit was another matter. It laced through the entire region of high-intensity radiation from 152 to 26,350 miles and from north 47 degrees to south 47 degrees, making 113 passes through the outer belt during its operating lifetime.

The spacecraft was another product of STL. They had already built and launched Pioneer 0 (Thor-Able 1), Pioneer 1, and Pioneer 2—Explorer 6 was an evolutionary extension of that work. All those early STL missions were initiated by the Air Force’s Ballistic Missile Division, when the three armed services were still vying for major roles in space, i. e., before NASA was formed in October 1958 to head the civilian space program.

Explorer 6 represented a major advance in the development of U. S. spacecraft technology and scientific research. Launched on 7 August 1959 by a Thor-Able-3 ve­hicle from Cape Canaveral, it weighed 141 pounds. One of its major objectives was to develop and test technologies that would be needed for deeper space flight, including journeys of millions of miles into interplanetary space. Long-term electrical power generation and data transmission over great distances were major challenges that guided some of the design considerations. Solar power generation coupled with stor­age batteries provided the electrical power. An onboard receiver facilitated Doppler tracking, fired the injection rocket, changed the rate of data transmission, turned on a simplified television system, and performed other functions. Three data transmit­ters were used—one operated intermittently with a five watt output for tracking and digital data transmission. It was designed so that it would be able to drive a 150 watt amplifier on future deep space missions. Two other transmitters radiated continuously

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at 100 milliwatts for analog data transmission. Since similar data were conveyed by the digital and analog systems, the older and more proven analog system was used primarily to monitor the performance of the new “Telebit” digital system that fed the higher-power transmitter.

The ambitious scientific program rivaled that of the Soviet Sputnik 3 program, in spite of Explorer 6’s smaller size and lighter weight, through its use of low-power miniature transistor electronics throughout. With this and the first Pioneer mission, the Air Force (and NASA, once it was formed) provided an opportunity for a new group of experimenters beyond those of us associated with the earlier Vanguard and Juno programs. A team under Robert (Bob) A. Helliwell, L. H. Rorden, and R. F. Mlodnosky at Stanford University provided a Very Low Frequency Receiver and studied the whistler phenomenon and radio propagation through the ionosphere. Carl D. Graves of STL studied electron density above the ionosphere by radio propagation measurements from the UHF and VHF transmitters.

Manring and Dubin at the Air Force Cambridge Research Center continued their earlier work by providing an impact microphone-type micrometeorite detector. Fluxgate and spin-coil magnetometers were developed, and their data were analyzed by an STL team that included Charles P. Sonett, Edward J. Smith, Paul J. Coleman Jr., J. W. Dungey, D. J. Judge, and A. R. Sims. They provided new information on the overall structure of the geomagnetic field and of its temporal variations.

A pair of instruments consisting of an ionization chamber and GM counter was provided by a team at the University of Minnesota headed by John R. Winkler and including Roger L. Arnoldy and Robert A. Hoffman. That group produced a set of rather complete contours of constant counting rate and radiation dosages. Interestingly, the contours displayed a shape quite different from those that we had deduced at Iowa at an earlier time. Their work helped to stimulate a period of energetic research during the next few years to better understand the trapping mechanism, injection and decay processes, and effects of solar variability.

A group at the University of Chicago provided a wide-angle, triple-coincidence, semiproportional particle telescope to investigate the solar modulation of cosmic radiation and the origin and structure of the Van Allen belts. That group was headed by John A. Simpson and included Charles Yun Fan and Peter Meyer at Chicago and Wilmot N. Hess and J. Killeen at the Lawrence Radiation Laboratory in California.

A scintillation counter was prepared by a team at STL consisting of Tom Farley, Al Rosen, and N. L. Sanders to examine the energy spectra of electrons and pro­tons. STL also provided an image-scanning television system. It obtained very low resolution pictures of the Earth that were a precursor to later cloud cover-observing instruments.

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An array of instruments was provided by STL to measure satellite orientation and various engineering parameters. Finally, a group of scientists used the orbit data for studies of lunar and solar perturbations, atmospheric drag, and effects due to ellipticity of the Earth’s equator. Those individuals included Yoshihide Kozai and Charles A. Whitney from the Smithsonian’s Astrophysical Observatory; Kenneth Moe from STL; and A. Bailie, Peter Musen, E. K. L. Upton from the Naval Research Laboratory.

Explorer 7 As mentioned in Chapter 10, serious planning for a second-generation U. S. satellite began as early as March 1958, buoyed by the elation over the successful Explorer I launch. It envisioned retaining the Juno I upper-stage arrangement but substituting the larger Jupiter Rocket for the Redstone first-stage booster, thereby substantially increasing the weight-lifting capability.

Initial planning by the Huntsville and Pasadena engineers and Washington officials proceeded at a rapid pace, and an experiment complement was soon identified. The Huntsville and Pasadena crews initially referred to that satellite as the International Geophysical Year (IGY) Heavy Payload, although the name Payload 8 (PL-8) was sometimes used. It was to include a package for continuation of our original Univer­sity of Iowa cosmic ray research objective, and that objective was quickly upgraded to follow up on the radiation belt discovery. The other experiments included a Solar X-ray and Lyman-Alpha Photometry Experiment under Herbert Friedman’s leadership at the Naval Research Laboratory (NRL), a Radiation and Heat Balance Experiment by the University of Wisconsin group consisting primarily of Verner Suomi and Robert Parent, and a Heavy Cosmic Ray Experiment using an ionization chamber developed at the Glenn L. Martin Company’s Research Institute for Advanced Stud­ies in Baltimore, Maryland, under the leadership of Gerhardt Groetzinger. Several engineering experiments were also included.

Primary support for the IGY Heavy Payload during the pre-NASA era was provided by the U. S. National Academy of Sciences, which renamed the embryonic satellite Payload 16 (PL-16). Presumably, that was because it was the sixteenth U. S. mission (both successful and unsuccessful) that carried the IGY banner. NASA, upon its formation, took over responsibility for the project and renamed it Satellite 1 (S-1), or the first in the series of NASA managed satellites. Its final name after launch became Explorer 7.

The original plan was to launch this satellite (seen in Figure 14.7) in mid-1958. Our initial schedule at Iowa called for delivery of a first flight cosmic ray instrument to Huntsville on 1 May. The initial schedule began to slip as the more urgent work on Explorers IV and V began to dominate the attention of everyone at Huntsville, Pasadena, and Iowa City. Further delays occurred as the Huntsville and Pasadena teams shifted to preparation for the Pioneer 3 and 4 shots.

A first attempt to launch S-1 did not occur until 16 July 1959. At liftoff, the power supply for the guidance system failed, and the vehicle was destroyed by the range safety officer 5.5 seconds later. Of course, by that time, the vehicle was barely off the ground, and the destruct command spilled the entire load of fuel and oxygen onto the launch pad. An enormous fire resulted, and those of us in the blockhouse remained sealed there for over an hour as the firefighting crew fought to bring it under control. The blockhouse blast door was ultimately opened, and we emerged to see the wreckage of the vehicle and our payload strewn around the area. I recovered the charred and melted remains of my cosmic ray instrument and a few other bits and pieces, which I retained until turning them over to the Smithsonian’s Air and Space Museum several years ago. Ernst Stuhlinger and I also examined a four foot rattlesnake that had been cooked by the conflagration.

Nearly three months elapsed before a second launch could be attempted. That happened on 13 October 1959, with a picture perfect launch of Explorer 7. The new

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satellite was placed in an orbit that ranged from 356 to 667 miles in height, high enough that the satellite is still orbiting the Earth 50 years later. Its orbital inclination was about 50 degrees, carrying the satellite far enough north and south to provide valuable new information about the Earth’s trapped radiation.

Suomi and Parent’s heat balance instrument worked perfectly. It initiated the era of satellite studies of the Earth’s climate. Using both satellite observations of the Earth’s heat balance and atmospheric cooling rates measured by net flux radiosondes, Suomi was able to establish the important role played by clouds in absorbing radiated solar energy. Those observations established that Earth’s energy budget varies markedly due to the effect of clouds, the surface albedo, and other absorbing constituents. Using these instruments, Suomi and his team discovered that the Earth absorbed more of the Sun’s energy than originally thought and demonstrated that it was possible to measure and quantify seasonal changes in the global heat budget.

By the time of the Explorer 7 launch, Gerhardt Groetzinger, originator of the Heavy Cosmic Ray Experiment, had died. Martin A. Pomerantz, of the Bartol Research Laboratory, took over the experiment and published results in several papers.11

The twin-GM counter cosmic ray instrument was developed by the author, with major assistance by Bill Whelpley. Graduate student John W. Freeman calibrated the counters. The experiment’s purposes were to provide a “comprehensive spatial and temporal monitoring of total cosmic ray intensity, the geomagnetically trapped corpus­cular radiation, and solar protons.” It operated for more than 17 months, broadcasting its data on two frequencies: 108.00 MHz and 19.994 MHz. That second transmitter was set to the low frequency, with a relatively high output power level of 0.6 watt, in order to make it easy for widespread participation in data recovery by radio amateurs and other interested persons.

The particle measurements from our instrument were somewhat anticlimactic. By the time the satellite had finally been launched, Explorer IV, also with a high orbital inclination, had already provided key information on the structure of the lower fringes of the radiation belts. More discriminating instruments for mapping the radiation belts, identifying the causative particles, and learning of their energy spectra had been operated on Sputnik 3 and Explorer 6. Furthermore, the wide-ranging orbit of Explorer 6 and deep space trajectories of Pioneers 3 and 4 had extended the observations much farther into space. Nevertheless, the Explorer 7 counters provided good observations of short – and long-term temporal variations over a relatively long period, from launch on 13 October 1959 to early March 1961.

Brian O’Brian joined our group as an assistant professor in August 1959 and became a major player in the Explorer 7 analysis effort.12

Vanguard III Vanguard III, launched on 18 September 1959, used the seventh and last launcher built under Navy aegis for the IGY. Somewhat heavier than

OPENING SPACE RESEARCH

the earlier Vanguards due to an improved final-stage rocket, at a bit over 50 pounds, it carried three primary instruments, a magnetometer by Jim Heppner and his group at GSFC to measure the shape and intensity of the Earth’s mag­netic field, an array of micrometeorite and other environmental sensors by Herman E. LaGow and his group at GSFC, and a pair of ionization chambers by Herb Friedman and his group at NRL to measure the Sun’s X-ray and ultraviolet emissions.

The thousands of magnetic field measurements obtained during its 84 day period of operation provided a charting of the Earth’s magnetic field with an accuracy far greater than hitherto achieved.13 Furthermore, the magnetometer’s measurements of very low frequency signals known as whistlers yielded estimates of electron densities in the high atmosphere.

The impact rate of interplanetary matter was highly variable. No penetrations of the satellite’s shell were detected, and the impact rate was found to be low enough so as to present only a minor hazard to future spacecraft. Even at that, analysis of readings from the micrometeorite detectors put the accumulative influx of cos­mic dust impinging upon the Earth at an impressive figure of about 10,000 tons a day.

The experience gained in the Vanguard program led to a long series of Explorer and Interplanetary Monitoring Platforms at the new GSFC in Greenbelt, Maryland, that continued until the recent past. Those craft provided opportunities for scientists who had cut their teeth on Vanguard to continue their work and for a fresh wave of emerging scientists to join in the grand adventure.

Pioneer 5 Pioneer 5 was a continuation by the Air Force, NASA, and STL of the work begun with Pioneers 0, 1, and 2. Its primary purposes were to further develop the technology needed for deep space operation and to make scientific measurements in space at a distance well removed from the Earth’s influence. The structure, solar paddle arrangement, and weight (about 95 pounds) were all generally similar to those of the earlier missions, and the scientific instruments were furnished, by and large, by the same group of experimenters. The previously anticipated 150 watt amplifier was added to provide the radiated power needed for long-distance interplanetary communication.

Pioneer 5 was launched on 11 March 1960 into an orbit around the Sun lying between the orbits of Venus and Earth. Its apoapsis (greatest distance from the Sun following its final orbital injection) was 0.993 astronomical unit (AU) and its peri – apsis was 0.706 AU. It requires 311.6 Earth days for each complete circuit around the Sun.

Data were received from the craft at 64, 8, and 1 bits per second, depending on distance from the Earth and the size of the receiving station antennae. Most of the

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telemetered data were recovered by the radio telescope at Jodrell Bank Observatory in England and by a tracking station in Hawaii. Useful data were received from the spacecraft for 50 days until 30 April, after which telemetry noise and weak signal strength made useful reception impossible. During the operational period, the high-power transmitter was commanded on about four times each day for 25 minutes duration each time. A new distance record was set for radio reception in interplanetary space when Jodrell Bank received a faint but readable signal from over 22 million miles away.

The mission provided the first measurements of the magnetic field in deep inter­planetary space and of its variations. Most notably, it found that the field did not drop to zero at distances well removed from the Earth but that the Sun’s field remained detectable there. It also measured solar flare particles and cosmic radiation in the interplanetary region.

S-46 It must be noted that throughout the rest of the 1950s, both the Soviets and Americans continued to have a substantial number of disappointing launch failures. One of those was the satellite that we built at Iowa as project S-46. The S-46 mission had a special significance for me, as the project served as the subject for my Ph. D. thesis in electrical engineering.14

This was the second spacecraft that was largely university built, following on the heels of the State University of Iowa’s earlier Explorer IV (and failed Explorer V). The scientific objectives were chosen to examine a manageable subset of the many then – prevailing questions about the high-intensity radiation belt structure and composition. For that purpose, the satellite was designed for an orbit with a high eccentricity and inclination.

Specifically, with that satellite, we hoped to achieve the following:

• monitor the intensity structure of the two principal zones of geomagnetically trapped radiation over an extended period to help establish the origins and gross dynamics of the two zones

• study the correlations with solar activity and with various geophysical phenom­ena such as aurorae and magnetic storms

• study the particle composition and energy spectra of the respective components

• make a first exploratory study of the energy flux of very low energy trapped particles by use of zero-wall-thickness detectors

Built with NASA support, with Les Meredith at GSFC serving as the payload supervisor, our Iowa group did the overall mission and spacecraft design and designed and built the scientific instruments. The major working partners were, again, our friends at the Army Ballistic Missile Agency (later NASA’s Marshall Space Flight Center), who built the spacecraft mechanical structure, battery, solar power system,

OPENING SPACE RESEARCH

FIGURE 14.8 The S-46 satellite payload. The central cylinder was the familiar six inch in diameter instru­ment container, with the detectors in the portion that protrudes from the top of the cubical solar cell array. The black circles on the top plate of the cylinder are some of the openings for the detectors.

and telemetry system. They also handled all aspects of the launch vehicle preparation and launch.

I continue to marvel at the wonderfully pleasant and productive working envi­ronment that existed between our groups. Individuals there with whom I worked closely on this mission, in addition to Ernst Stuhlinger, were Josef Boehm, H. Burke, Charles Chambers, Gerhardt Heller, Hans Kampmeier, Fred Speer, Sam Stevens, Art Thompson, and Hermann Wagner.

Tracking and telemetry reception was to have been done by a network of NASA stations that would have provided about 90 percent recovery from the highly eccentric orbit. My primary interface there was, again, John Mengel at GSFC.

The instruments included a pair of cadmium sulfide solid state detectors, two GM counters in an electron magnetic spectrometer arrangement, and a third GM counter to establish data continuity with the measurements from Explorers I, III, and IV.

CHAPTER 14 • EXTENDING THE TOEHOLD IN SPACE 417

The detectors were designed, prepared, and calibrated by a group of rising students. John Freeman led the CdS detector effort, assisted by Guido Pizzella, James (Jim) D. Thissell, and Carl McIlwain. Curtis (Curt) D. Laughlin took the electron spectrometer assembly, and Lou Frank led the GM counter calibration effort. Wonderfully effective engineering support was provided by students H. Kay McCune, Bill Whelpley, and Donald (Don) C. Enemark.

The mechanical components of the payload were machined in the department instrument shop by Ed Freund, Robert (Bob) Markee, Robert (Bob) Russell, Edward (Ed) McLachlan, and Michael (Mike) McLaughlin, under the general supervision of its leader, J. George Sentinella. Drafting was provided by Ray Trachta, G. G. Lippisch, A. M. Hubbard, and B. W. Fry. Others helping with the project at Iowa included Gene Colter, John Davies, Chuck Horn, Lucille Lin, Wei Ching Lin, Thomas (Tom) Loftus, Bob Wilson, Keith Wilson, and Andrace Zellweger.

The completed satellite payload is shown in Figure 14.8. The launch attempt was made on 23 March 1960, but the assembly consisting of the second-, third-, and fourth-stage rockets did not function properly. Van Allen made a valiant ef­fort to arrange a second attempt, but an additional launch vehicle was simply not available.

Fortunately, comparable instruments and their derivatives were flown successfully on later spacecraft, most notably on Explorer 10 launched on 25 March 1961, Explorer 12 launched on 15 August 1961, Explorer 18 (Interplanetary Monitoring Platform 1) launched on 27 November 1963, and the Eccentric Orbiting Geophysical Observatory 1 launched on 5 September 1964.

My wife, Rosalie (who now prefers the shorter name “Ros”), was an active partner in the events related in this story. I am indebted to her for that enthusiastic participation and for her forbearance and support during the more than ten-year period of preparing this manuscript.

James A. Van Allen, in addition to providing the leadership for much of the program at Iowa, encouraged and helped me in writing this story. Throughout the process of researching and drafting this manuscript, he provided information and commented on portions of the text. Special thanks are due to him for preparing the book’s foreword.

Leslie (Les) H. Meredith, the first graduate student with whom I worked in the Iowa Cosmic Ray Laboratory, introduced me to the art of balloon instrument design and fabrication. He provided substantial previously unpublished technical and anecdotal information about the rockoon expeditions that has been incorporated into this book. He reviewed the full manuscript and provided substantive comments.

Frank B. McDonald, from my first association with him at Iowa in 1953 through our most recent discussions, has been a strong guide, personal booster, close friend, and a major factor in my professional development. He reviewed segments of the manuscript during its preparation and provided important comments on the full draft.

Ros and I developed especially close personal and professional bonds during our university years with Carl E. McIlwain and his wife, Mary; Laurence (Larry) J. Cahill Jr. and wife, Alice; and Ernest (Ernie) C. Ray and Mary. Ernie passed away before I began writing this book, but Mary Ray assisted in relating Ernie’s role. Carl McIlwain and Larry Cahill reviewed portions of the manuscript during its preparation and provided very valuable assistance by reviewing the full text.

Special thanks are extended to Nancy Johnston and Mary McIlwain, who painstak­ingly proofread the full manuscript.

Others, too numerous to list, encouraged me and provided input during the long process of writing this book. Many of them are mentioned in the text. Grateful thanks are expressed to all of them.

Endnote

1 It can be argued that the Space Age started earlier with, for example, the flight of balloons into the high atmosphere in the early Twentieth Century, or the first launch of a V-2 rocket to a height greater than 100 miles in 1946. In this work, I somewhat arbitrarily mark the beginning of the Space Age with the first durable excursion into the region above the Earth s sensible atmosphere, that is, with the launch of Sputnik 1 on 4 October 1957.