Category Dreams, Technology, and Scientific Discovery

Iowa City was a rather small city. As the university’s program for exploration with balloons and rockets developed in the early 1950s, the local media took an increasing interest in the work. It enjoyed growing coverage in the Iowa City Press Citizen, the university’s Daily Iowan, the Cedar Rapids Gazette, the Des Moines Register and Tribune newspapers, and local radio stations KXIC and WSUI.

I enjoyed a unique outlet. Dad had a radio program over station KXIC six mornings each week. Although it focused on rural news and events, his natural interest in science and his pride in his son’s rocket and satellite work led to my appearance on his program on a fairly regular basis.

As the time for the opening of the IGY approached, there was a growing public awareness that entry into space was near at hand. As our cosmic ray instrument began to take visible form, more and more articles appeared to describe our work.4 In mid- 1957, there was a flurry of activity in the local press as our instrument package neared its final form.

Through lectures at service organizations, teachers’ and other professional con­ferences, industrial companies, and other universities and colleges, we described our evolving work to a wider audience. I even described the Vanguard program to a small group of farmers at a plowing match where I stood on a wagon to describe the prototype instrument. Many years later, I received a letter of thanks from one of that day’s attendees. He stated, “Your presentation enabled… us to avoid the paranoia that surrounded Sputnik armed with the confidence that our side was working on a satellite which would be more sophisticated than that of the Russians. Our confidence was well placed.”

Van Allen was, naturally, the focus of much of that attention. Our satellite launches and the discovery of the Earth’s high-intensity radiation belts thrust our campus group into the national and international scientific and public spotlights. To cite only a few examples of the coverage, Life magazine reporters interviewed Van Allen and took pictures of our handiwork on 9 May 1957 for major coverage in their magazine. On the occasion of the Explorer III launching on 26 March 1958, the Cedar Rapids Gazette featured an article on its front page that proclaimed, “A Son and a Satellite for SUI’s Ludwig.”5 At the end of March, a CBS television crew arrived, and Walter Cronkite interviewed Van Allen for his news broadcast. And so it continued throughout the rest of the time that I was in Iowa City.

Admittedly, I reveled in all the attention.

After the initial development and field proof of the rockoon technique in 1952, Van Allen, his students, and Gottlieb were eager to put this new tool to further use. Expeditions were mounted in the summers of 1953, 1954, 1955, and 1957 to exploit that new capability. The focused goal of the one in 1953 was to extend the 1952 observations to a larger latitude range and to obtain more information about the nature of the particles.

Les Meredith prepared a set of rockoons that were generally similar to those he flew in 1952, including the use of the same Deacon jet-assisted-takeoff-based rockets. Larger Skyhook balloons (up to 100 feet in diameter) were selected to increase the altitude of the rocket firing to as high as 70,000 feet (over 13 miles), thus permitting peak rocket altitudes of well over 300,000 feet (57 miles). A cutoff device was added near the balloon’s neck to drop the rockets for safety reasons if, after a few hours’ flight, the balloons descended below 30,000 feet or the rockets did not fire. His total payload weights were 30 pounds, 2 pounds heavier than the 1952 payloads.

Student Robert (Bob) A. Ellis Jr. had helped with the rockoon work from the beginning but elected in 1952 not to commit to them for his thesis work. When it was time to prepare for the 1953 expedition, however, Bob had become a convert and wholeheartedly joined that endeavor. He prepared rockoon instrumentation to measure total cosmic ray ionization.

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His instrument was generally similar to his 1952 instrument, as shown earlier in Figure 1.3 (b). The complete array of instruments is shown as they were prepared for shipment in Figure 2.2.

For that second rockoon-launching expedition, I received my introduction to the art of rocket instrumentation by helping both Les Meredith and Bob Ellis assemble their packages. The extended field operation, sponsored by the Office of Naval Research (ONR) and Atomic Energy Commission as Project Muskrat, took place during July, August, and early September 1953 aboard the U. S. Navy icebreaker USS Staten Island.2 The State University of Iowa (SUI) expedition members were Mel Gottlieb as team leader and students Meredith and Ellis. They were assisted by the always – capable and valuable support of the ONR’s Lieutenant Malcolm Jones.

Boarding the icebreaker USS Staten Island at Boston, the Iowa threesome set up a trailer laboratory on the helicopter flight deck. A Naval Research Laboratory (NRL) group led by Herman E. LaGow also boarded with their rockoons and receiving

station to measure upper-atmosphere pressure, temperature, and density. His flights marked the beginning of rockoon flights by that organization.

The SUI contingent established a milestone in racial desegregation on that sailing. It was customary for the Navy to accord civilian researchers officer rank when on board their ships. When the Iowa group arrived in Boston, the ship’s crew discovered that Bob was black. The only blacks on board the ship in the past had been as members of the nonofficer crews—blacks had never been admitted to “officer country.” After due deliberation, the captain went ahead and housed Bob in the officer’s quarters and admitted him to the other officer’s facilities. Bob became an instant hero of the black crew members.3

The ship sailed from Boston harbor on Saturday, 18 July, and progressed toward Newfoundland and the Labrador Sea. After an initial failed launch attempt late on the first day, they tried igniting a firing charge suspended under a captive balloon off the ship’s fantail and concluded (probably erroneously) that they had installed the igniter backward for the first launch attempt. While three more unsuccessful rockoon flight attempts were made during the following day, the team worked feverishly to determine the cause of the problem. That first try at 6:30 AM, after meticulous verification that the igniter was properly installed, failed. The next try was with a bag of smokeless powder next to the igniter. That also failed. They thought their problem might be that

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a Bakelite plug in the rocket motor might have blown out when the rocket reached altitude. A third try to test that theory at about 6:00 PM also failed. That evening, they wired Van Allen to see if he could throw any light on their difficulties.

The ship traveled in poor visibility past the coast of Newfoundland during most of Monday. That morning, the researchers devised a rig with a cluster of small weather balloons to make a flight test of the firing box and igniter. Instead of the precious rockoon instruments, that flight used a radiosonde transmitter and receiver of the type used widely for meteorological sounding. Late that afternoon, they launched that flight but were further frustrated when the radiosonde’s shipboard receiving station failed.

Meredith worked all that night to build another variation on the small-balloon test system. For that test, another firing box was coupled to one of the rockoon flight transmitters, and the rockoon receiving station was set up to receive its signal. By Tuesday afternoon, although the ship was rolling about 10 degrees and the wind speed was near the maximum speed of the ship, they were able to attempt a launch of this new setup. Because of conditions, it was difficult to measure the balloon lift, and some of the balloons received small holes because of the difficult balloon-handling operations. The assembly rose only a few thousand feet before it drifted out of range.

At that point, the team decided that a vacuum chamber test might be informative, since the igniters had been designed originally for use at ground level. Finally, they hit pay dirt—that test on Tuesday evening with a vacuum chamber that Herman LaGow had brought along showed that the firing squib was blowing the igniter’s main

powder charge apart without burning it in the rarified air where the rockets were being expected to fire. They thought at first that they would pressurize the rocket, but that proved too difficult to do reliably in the field. Finally, on Wednesday, Lieutenant Jones devised a new arrangement, with a wire screen to reinforce the igniter’s plastic case and with black powder strung on the igniter’s hot wire. The black powder burned when the wire was heated by a firing current, and that ignited the main igniter charge. That field invention (referred to afterward as the Jones Igniter) worked well throughout the rest of the expedition.

Les Meredith’s informal expedition notes make very interesting reading, both in de­scribing an Arctic field expedition and in conveying a highly personalized impression

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of the problems, excitement, and sense of adventure. His entry on their first day out, Saturday, 18 July 1953, elaborates on some of the initial operational and programmatic difficulties, starting with their departure from Boston:

Last night about midnight, the ship got some messages that it was to proceed to Saglek, Canada, “without delay.” We were supposed to leave this morning on our project. The sailing time was set at 9:00 A. M. In the literal meaning, the ship was to proceed to Saglek and shoot our rockets later. Gottlieb was all for getting off the ship and coming home. Since the ship was leaving at 9:00, however, there was not time to get everything packed so we stayed. It turned out the captain is a reasonable type of person and he was willing to delay the ship an hour or so to get a rocket off, but he could not sit and wait if there was a wind, or it was night, etc.

Today the wind has been only about five mph and it’s been a beautiful cloudless day. As a result, we were able to get one of Ellis’ [instruments] off about 5:30 PM. We had to wait that long so we would be far enough out. We left Boston about 9:15 AM and steered right along at about 14 knots all day. Ellis’ didn’t fire. We were able to watch the balloon with naked eye for over two hours. Then it got dark. It was just a small white spot and hard to find and keep track of. This evening we put the firing charge on a captive balloon off the back of the ship and blew it up with our firing mechanism. We figured out we had put it in the rocket backward.4

The ship arrived at Saglek Bay on the northern Labrador coast (about 58.5 degrees north geographic latitude) during the early morning of Thursday, 23 July. By that time, they had discovered the reason for their earlier problems and had high expectations that the next launch would be successful. But, since they were close to shore, rock – oon launches were not advisable. Les’ entry for that day described a day of forced relaxation for the researchers:

This has really been a day and a half. This morning we got up to find ourselves anchored at the end of Saglek Bay. The weather was beautiful. With a sweater, it was about right in the shade and a little warm in the sun. There were a few clouds and a slight breeze. The only drawback was the great number of large mosquitoes and flies. The morning was largely spent waiting for the afternoon.

In the afternoon, we took a landing boat to the beach. There was an abandoned army base there. All that was left was a barn and lots of empty oil drums. We hiked inland and climbed a mountain which was at least 2000 feet high. With my sweater on, I worked up a good sweat. Then we came down and walked along and fished in a clear mountain stream. In one pool, there were three or four large rainbow trout. They wouldn’t bite so we first threw rocks at them and ended up swimming in the pool. It was three or four feet deep and fifteen by twenty feet across. The bottom consisted of a large slab of rock, no sand or mut [mud?]. There were rapids at both ends. Then we came back to the ship. There was grass in places, a few low shrubs, and many different types of flowers including dandelions. Mostly there was what looked like a type of moss almost, and, of course, lots of rocks. This was especially true up on the mountain. The view from the mountain was really something. There were mountains all around and down below were the green valleys, lakes, and the ships in the harbor. There were four other ships here. The only life we saw were the fish, and some small gray birds (flies and mosquitoes). There were lots of holes in the ground, but we didn’t see what lived in them. Sunset was at 8:00 PM, EST tonight.5

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They were able to make the next launch attempt, using the field-rigged Jones Igniter, on Friday, 24 July, soon after the ship left Saglek Bay on its way toward Resolution Island. That also failed, but for a different reason—the weather worsened as they left the shelter of the bay, so there was a residual wind across the deck when the rockoon was released. The firing box was knocked off the load line during its initial ascent when it snagged on a flight deck net.

That incident highlighted an important aspect of balloon launches. As discussed earlier in connection with ground-based launchings, if a balloon is inflated when the wind speed relative to the launch site is more than a few miles per hour, the anchored balloon is blown aside above the payload. If the balloon is released under those conditions, gravity causes the payload to swing under the balloon like a pendulum, and it crashes into the ground, ship, or sea, nearly always damaging the instrument.

A ship can follow the wind to mitigate this effect. The standard operating procedure was to tie a small weather balloon to the ship’s railing so that it floated 100 feet or so above the deck in full view of the conning officer. The conning officer’s task was to steer the ship and adjust its speed to keep it centered under the balloon. With that accomplished, the relative wind speed across the deck was minimized, and inflation and launch could be accomplished with safety.

Of the five unsuccessful initial launching attempts, the first and third expended two of Ellis’ valuable instruments, and others wasted three of Meredith’s payloads.

On Saturday, 25 July, the ship reached Resolution Island, located at about 61.5 degrees north geographic latitude, across the mouth of Hudson Strait from northern Labrador. For the next considerable period, the ship worked in the Reso­lution Island area. Meredith’s entry for Sunday, 26 July 1953, indicates the general nature of the ship’s primary mission:

Nothing happened again today. We sat around off Resolution Island. It was overcast all day and sprinkled off and on. The main features were the large swells, which kept the boat rocking all day.

During most of the day, we had a line from the back of our ship to the front of a larger ship, a LSD (floating dry dock). Our job was to keep the nose of this ship pointed into the swells while it put small landing boats into the water, through a door at its back. Those boats were to take supplies into a radar station on the island, as the larger boats were afraid to go in because of the ice. Whether the small boats made it, I don’t know.

There didn’t appear to be too much ice. Quite a few small pieces, but nothing big.

Rolls of 10° were common. Some were as high as 20°. One was 30°. On this one, I went right out of my chair.6

On Tuesday, 28 July, 10 days after leaving Boston, the ship was again in sufficiently open water, and the Iowa team was finally able to launch its first successful flight. Meredith’s daily entry for that triumphal day reads:

This morning we got up at 4:30 A. M. for a flight. The wind was about ten miles per hour when we started and there was a heavy overcast. It sprinkled off and on, mostly on. At about

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6:30 A. M. we got the flight off. It was one of mine and had a hot wire igniter. It fired at 8:00 A. M. right on schedule. The reliability of the results is questionable. The terrible radio propagation and large aurora last night, which I didn’t see, may be related to results obtained. We’ll have to make another flight to check. When we launched, the wind was about twenty miles per hour, the maximum speed of the ship. This coupled with the fact that the General Mills load line was just barely long enough, three feet left on, which made the launching touch and go. Anyway, it went.7

Auroras occur in the upper atmosphere (predominantly above 60 miles altitude) at high northern and southern latitudes (centered at about 67 degrees north and south geomagnetic latitude). They are caused by energetic particles that are guided into the upper atmosphere by the Earth’s magnetic field. Some of those particles, those usually associated with the visibly diffuse aurora, are electrons and protons precipitating from the magnetospherically trapped particle populations (the later-discovered outer Van Allen Radiation Belt). Other particles, often associated with the more variable discrete aurora, are predominantly electrons arriving from outside the magnetosphere, primarily from the Sun.8 9

During the following days, the ship continued to work in the Resolution Island area in persistently marginal weather. But that Saturday evening, the scientists were able to talk the captain into sailing into open water to attempt another rockoon launch. During that attempt (with an NRL payload), a frightening incident occurred that could have been a major disaster. A wind gust came up after the balloon had been inflated. The balloon acted like a huge sail, and the resulting force broke the 1000 pound test line anchoring the balloon to the deck. The load line had not yet been attached to the rocket, but was lying coiled on the deck. Mel Gottlieb happened to be standing on that line when the balloon surged upward. Fortunately, he jumped free, and the line did not become entangled in his legs. If it had, the balloon would easily have borne him aloft, and they would have had no way to cut him down. That forcefully reminded everyone that shipboard rockoon launching is, fundamen­tally, a dangerous operation, and that strict adherence to rigorous safety practices is essential.

The ship remained in the Resolution Island and nearby Frobisher Bay areas for nearly two weeks, working on its primary mission to escort Navy ships through the ice. Departing there on late Wednesday, 5 August, it proceeded up the Davis Strait, across the lower end of Baffin Bay, and through Lancaster Sound to Resolute Bay (not to be confused with Resolution Island). Resolute Bay is located on Cornwallis Island, lying just northwest of Baffin Island and west of larger Devon Island. (See Figure 2.14 for the relative locations of those sites.)

More rockoon flights were made during that leg of the trip. By the time the ship reached Resolute Bay early on 10 August, a cumulative total of 10 SUI and three NRL rockoons had been launched. The icebreaker remained at Resolute Bay for some

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time, resuming its primary mission to support a number of ships in the icy water. Les Meredith left at Resolute Bay on 12 August via a Royal Air Force Lancaster mail plane so that he could begin his classes with the start of the new academic year. He returned to Iowa City via a circuitous path through Alert Base on the far northwestern shore of Ellesmere Island; Thule, Greenland; and Boston. The ship eventually proceeded to Thule, and then returned the rest of the expedition party to Boston on about Septem­ber 5, with the expedition teams firing six additional SUI and two more NRL rockoons along the return path.

In all, 16 launch attempts were made by the Iowa group, and 6 were made by the NRL scientists. Seven of the Iowa instruments and three of the NRL instruments reached useful altitudes and produced usable data. Three of the successful Iowa flights carried Meredith’s single GM counters, and the other four carried Ellis’ ionization chambers.

Data from one of Meredith’s 1953 flights confirmed and extended his 1952 results. Those combined results served as the basis for his Ph. D. dissertation, as mentioned at the end of the previous chapter. Ellis’ flights, made at about 76 degrees, 86 degrees, and 56 degrees north geomagnetic latitude, served as the basis for his Ph. D. dissertation, where he reported that higher-charged primary cosmic ray nuclei (charge greater than or equal to six) were absent or nearly absent at magnetic rigidities below 1.5 x 109 volts.10

As mentioned briefly in the prologue, flights measuring cosmic ray intensity typically show an initial rise in the counting rate as the altitude increases. The rate reaches a peak value when the instrument passes through the so-called Pfotzer-Regener maximum (often shortened to Pfotzer maximum). That occurs where the counter detects the combined effect of incoming primary cosmic rays that have not yet interacted with the atmosphere, plus secondary particles that result from collisions of primary particles with atoms and molecules in the atmosphere. As the instrument proceeds even higher, the counting rate drops slightly and eventually flattens to an essentially constant value. At that point, the counter is too high to see many of the secondary particles, so that it registers almost exclusively the incoming primary cosmic rays. During rocket descent, the instrument passes again through the Pfotzer-Regener maximum, and the counter rate then drops to its sea-level value, where a preponderance of the primary and secondary cosmic rays have been absorbed by the atmosphere. Figure 2.5 beautifully illustrates this typical pattern.

The constant, or “plateau,” value above the Pfotzer-Regener maximum was the primary information for which the 1952 and 1953 expeditions were mounted. The goal was to determine those plateau values for various geomagnetic latitudes, in order that the effect of the Earth’s magnetic field could be used to help determine the energy spectrum of the primary cosmic rays.

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Although Meredith was dubious at the time about the quality of the data from the launch on 28 July 1953 (SUI flight 13), it turned out to be valid and resulted in an important new discovery. Launched just northeast of the mouth of Hudson Strait at about 74 degrees north geomagnetic latitude, it was the first flight to detect an anomalous radiation superimposed upon the normally expected cosmic rays, as shown in Figure 2.6. Flight of another of his instruments on 30 August (SUI flight 20) at about 64 degrees north geomagnetic latitude during the ship’s return showed a similar effect.

The data from flight 13 showed the expected counting rate during the early and late phases of the flight, where the instrument passed over the Pfotzer-Regener maximum soon after the rocket fired and again shortly before impact. But at higher altitudes, where the rate was expected to remain essentially constant, it climbed to a much higher value. The peak rate during that flight reached about four times the anticipated plateau value.

Because this anomalous effect was seen only during the two flights made in the neighborhood of the auroral zone, it was surmised that the observed extra radiation was linked to the production of the visible aurora. Those two flights were the basis

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for the original announcement in early 1955 of what was quickly termed the auroral soft radiation.11

It was tentatively hypothesized that the counters were seeing the high-energy tail of the particles producing the aurora, and that they probably were predominantly elec­trons having kinetic energies in the neighborhood of 1 MeV That early interpretation was modified after follow-on investigations in 1954 and 1955, as related later.

Laurence (Larry or Bud) James Cahill was born on 21 September 1924 on the family farm southeast of Bangor, Maine. He spent his childhood with his parents in Bangor, where all of his early memories are focused. He attended kindergarten, grade school, and high school in Bangor’s public schools.24

Larry developed a strong interest in science at an early age. Throughout his secondary and primary school years, Larry gained access to reading material through the excellent library situated next to the high school. He visited it several times a week to check out books and magazines. Although the subjects varied widely, he particularly liked the Popular Mechanics and Popular Science magazines. Academically, Larry doesn’t consider himself to have been an outstanding student throughout his primary and secondary school years, but he did well in the subjects he liked, including mathematics, history, and chemistry. Larry graduated from high school in June 1942.

Recipient of a university scholarship at the University of Maine at Orono, Larry attended that school for the 1942-1943 academic year. Because of his high school focus in chemistry, he enrolled initially in chemical engineering. Soon disenchanted with the laboratory work in chemistry, he was attracted to physics, in which the university had an excellent program.

It was wartime, and Larry had enrolled in the Navy V-6 program in order to remain at the university. However, after the first year there, he yearned for a change and entered the competition for further schooling at the U. S. Naval Academy in Annapolis. Although he lost out on an appointment there (because of politics rather than lack of qualifications), he did win an appointment to the Army’s West Point, which he entered in June 1943. He spent the next three years there, during which time he also went through the Army Air Corps pilot-training program. Graduation in June 1946 was from both West Point and the flying school.

Following graduation, he took an assignment in the Air Corps in which he flew a progres­sion of fighter aircraft, beginning with transition training and then assignments in the F-51.

In mid-1947, he trained in the new F-80 jet fighters and flew them extensively during the next few years.

While in military service in what was by then the U. S. Air Force, Larry received his B. S. degree in physics from the University of Chicago in June 1950. He followed that with Air Force Special Weapons (to be understood as the atomic bomb) training at Albuquerque, New Mexico. He served from the fall of 1951 until August 1953 in French Morocco as the arming officer for atomic bombs in the heavy bombardment wing that was stationed there.

Larry left the air force in the summer of 1954 to pursue further university study. After visiting the campuses of the universities of Minnesota and Iowa, he decided to join the space research program at Iowa. Moving to Iowa City that summer with his wife, Alice, and their first two sons, Larry and Tom, he registered as a Physics Department graduate student for the beginning of the fall 1954 semester.

Discovering the possibility of employment in the Cosmic Ray Laboratory, Larry began work there soon after the start of his course work. Although Larry had had more formal academic training than the rest of us when we began work there, he quickly joined in the spirit of the laboratory, undertaking any tasks that needed to be done.

Larry received his M. S. degree in 1957 and his Ph. D. degree in the spring of 1959. That summer, he moved into a faculty position at the University of New Hampshire, where he led a first-rate space research group that is still active today. After nine years there, he

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joined the space research group at the University of Minnesota, where he served as one of its prominent researchers and departmental leaders. He remained there until retirement in 1989.

After retirement, Larry and Alice stayed in their home in Avon, east of the Twin Cities in Minnesota, for a number of years. In early 2001 they moved into Academy Village, a new community for academic retirees located about 20 miles east of the center of Tucson, Arizona. Alice died unexpectedly in 2009, but Larry continues to enjoy his residence in Academy Village.

Larry quickly began to develop the magnetometer. His twin scientific objectives were the study of the equatorial electrojet and a search for ionospheric electrical currents in the auroral zones. He later confessed that he didn’t know much about electronics at the time, but he promptly set about to learn what he needed to know.

His greatest challenge was to detect and isolate a very low level audio frequency signal from the instrument’s detector coil. That required an extremely high gain amplifier, sharply tuned to the expected proton precession frequency in order to separate the useful signal from the noise occurring at all frequencies. He found it very tricky to adjust that amplifier so that it had sufficient gain but did not break into continuous oscillation. Larry underscored that problem during our October 2000 interview:

My principal problem was oscillation of the high-gain, narrowband, tuned circuit, because it really was an oscillator, or very easily became an oscillator. [There was] a coil pickup— essentially a high-gain antenna—and a high-gain amplifier, all without shielding. [The com­ponents] were all in close proximity. I made tremendous efforts to work around [the problem, including twisting things, etc.]. … I can’t say that I ever completely solved that problem.

I [eventually] built 25 rocket [instruments], and some of them were quite stable against oscillation—some I couldn’t ever stop oscillating, and I didn’t ever fly them. It was a problem that never went away.25

After getting the instrument to work in the laboratory, Larry developed a version for a balloon flight to demonstrate that it could be made to work under field conditions. That balloon flight was made in early 1956, as described in Chapter 2. On that first flight, the instrument operated perfectly, successfully tracing the strength of the magnetic field at flight altitude from Iowa City to the vicinity of Chicago. Of course, no ionospheric current was expected or seen at that height or latitude—the flight was strictly for developmental purposes. The technical development and the balloon flight results were fully described in Larry’s master’s thesis.26

Larry then undertook the adaptation of his magnetometer for flight in the Loki rockoons. The primary change from the balloon hardware was the ruggedization necessary to withstand the extreme vibration and acceleration of the rocket during its burning. Although the instrument was not required to operate during the actual firing, it had to survive launch and commence normal operation immediately thereafter. Most

of the rockoon circuitry employed the Raytheon subminiature tubes that were being used at Iowa for most of the rockoon instruments. The transmitter still employed a larger vacuum tube, the same RCA type 3A5 acorn tube as was used in most of the Iowa balloon and rockoon instruments.

Larry, with help from undergraduate assistant Gary Strine, built, tested, and ad­justed the instruments. The testing and calibration included running back and forth between the laboratory and the yard on the west side of the physics building. There he set up a large coil to produce a magnetic field at its center that was equal to the one expected at flight altitude and latitude. With his instrument at that center location, as shown in Figure 4.4, they were able to tune the circuits for the expected conditions at their planned flight locations.

The next step was to make a test firing of a rocket carrying his instrument to check the instrument’s ability to operate at altitude after the trauma of the rocket firing. For that purpose, Larry joined the Iowa contingent’s expedition to Guam in January-February 1957, as mentioned earlier. He took three of his rockoon payloads for that first field test. He attempted to fly them in mid-February 1957. Unfortunately, that expedition did not produce useful results. He tried to launch from a small Navy Landing Ship, Tank (LST), but only two days were allotted for the exercise, and the team was unable to get the rocket and supporting equipment ready in time. Larry finally tried a ground rocket launch from a crude launcher, but he received the radio signal from the ascending rocket for only a few seconds.27

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In spite of that early failed attempt to field test his evolving instrument, Larry’s hard work did eventually pay off. He later conducted a very successful set of field rockoon operations with his magnetometer, as described later in this chapter.

Van Allen’s 1957 Loki II instruments The instruments that Van Allen took on his 1957 Arctic and Antarctic expeditions were reasonably straightforward derivatives of the instruments that Carl Mcllwain had developed and flown during his 1955 Arctic expedition. Van was assisted in that effort by graduate student Donald (Don) Goedeke and undergraduate assistant Donald (Don) E. Simanek.

Van Allen’s scientific objectives were as follows:

• To investigate the physical nature, energy, intensity, and latitude distribution of the auroral soft radiation that had been discovered on the earlier rockoon expeditions, including extension of the observations to the southern hemisphere.

• To investigate the total cosmic ray intensity through and above the atmosphere at various northern and southern latitudes during the period of maximum sunspot activity. This was a continuation of the original rockoon objective that he had laid out in 1951.

• To study the correlation of fluctuations of cosmic ray intensity with solar and magnetic data from ground stations, with cosmic ray data in balloon flights at Fort Churchill, Canada, and Minneapolis, Minnesota, and with neutron monitor data at various ground stations. This was a broader objective intended to supplement the wide range of observations being made under the IGY umbrella.

As his basic detector, his instruments employed the same type of Victoreen 1B85 GM counter that had been used in most of the Iowa balloon and rockoon instruments, beginning with Meredith’s first balloon flights in 1951. Two counters were used in each payload, one without shielding other than the counter wall and nose cone shell. The second counter had various amounts of either aluminum or copper shielding, in order to obtain improved information about the auroral soft radiation particle types and energies.

Two instrument types were identified in various logs and papers as Type A and Type B. As far as can be determined, the detector arrays in the two types were similar, but the Type B instruments contained different electronics, including a different way of modulating the transmitter. The payload weights were 8.5 pounds for the Type A and 11.5 pounds for the Type B instruments.

Van Allen and Cahill to theArctic The Iowa members of the 1957 Arctic expedition, Van Allen, Cahill, and undergraduate students Don Simanek (assisting Van Allen) and Gary Strine (assisting Cahill), joined their ship, the USS Plymouth Rock, at Norfolk, Virginia, where they helped load their instruments and set up their onboard laboratory.28 The ship was a Landing Ship Dock (LSD-29), a much later model of the

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ship that supported the 1955 rockoon expedition. It provided plenty of space for all of the helium bottles, supplies, rocket storage, and laboratory and for launching the rockoons from its helicopter deck.

The ship was commanded by Captain J. D. Lautaret, USN. Its primary mission was to resupply several American bases in Greenland. As on previous expeditions, the rockoon support was an add-on mission, with the ship pausing en route to launch the rockoons. A reasonable distribution of launch positions was planned, extending from about halfway between the northern tip of Newfoundland and the southern tip of Greenland, up the Davis Strait and Baffin Bay, to Thule, Greenland, the turnaround point. (See Figure 2.13 for a general orientation.)

The rockets employed for all launches on this expedition were modified Loki Phase II rockets, known by then as the Hawk, an improved version of the Loki Phase I rockets used on the 1955 expedition. Their greater propulsion capability permitted flights to higher altitudes and/or with greater payload weights. The basic propulsion unit was a solid-fuel cylinder three inches in diameter and five feet long. As with the earlier Phase I rockets, its fins were larger than the standard production fins to stabilize the rocket when it was fired in the rarified upper atmosphere. The basic rocket’s modifications also included an attachment hook for suspension from the balloon and a modified forward end for attachment of the instrumented nose cone. The nose cones were, as before, three inches in diameter and about three feet long, as seen in Figure 4.5.

Balloons from Raven Industries were used for those flights. They were made of 15 60 foot long gores of 0.00075 inch thick Visqueen-A laminated polyethylene, joined to form an approximate 38 foot diameter sphere, with an attached 50 foot long inflation tube. Partly inflated at sea level, the helium expanded during ascent to create an inflated volume of 28,000 cubic feet. The material of the balloons weighed 17.5 pounds, and they reached a maximum altitude of 82,000 feet (over 15 miles) with a 42.5 pound payload consisting of a rocket and its instrumented nose cone.29

The costs of the flights were unbelievably low, even by the standards of the time. In 1959 dollars, the costs for the rockoons were $580 each for the Hawk propellant units, $40 for the firing boxes, $100 for the balloons, $30 for the helium, plus the money provided to the university for instrument development and fabrication.

The ship departed from the naval shipyards at Norfolk on 1 August 1957, passing up the New England coast, across the Grand Banks off the east coast of Newfoundland, and then on an essentially direct course to its first port of call at Sondre Sund, about halfway up the west coast of Greenland. While thus sailing south of, completely through, and above the main auroral zone, they launched two of Cahill’s magnetome­ters and three of Van Allen’s instruments. Four of the five achieved useful balloon altitude. One of Cahill’s instruments provided usable data during the rocket phase. Two

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of Van Allen’s instruments provided good balloon phase data, and one also produced usable rocket phase data.

The stop at Sondre Sund on 7 August was brief, with departure later the same day. The next leg to Thule was made rather quickly, with only two launches en route. Cahill’s one attempt ended in failure of the rocket to ignite, while Van Allen’s provided good balloon and rocket phase data.

The ship stayed at Thule for a brief day or two, and then departed for its southward return. Van Allenmade a cluster of three launches atabout 77 degrees north geographic latitude, well north of the auroral zone, of which two produced good balloon and rocket data, while the last one, carrying the first of his three new Type B instruments, experienced another rocket igniter failure.

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From there, the ship sailed uninterrupted for about 15 hours, by which time they were again approaching the zone of the visible aurora. During the next three days, the team launched eight more rockoons. Two of those were Cahill’s, of which one experienced instrument failure, while the other reached a satisfactory rocket altitude but apparently failed to produce scientifically useful data. Of Van Allen’s six attempts, one rocket failed to fire, and three other flights experienced instrument problems. Thus, Van’s southbound auroral zone flights produced five sets of balloon data, but only two sets of usable rocket data.

It should be noted that the balloons performed admirably throughout that expedi­tion, with all but one of the 18 launch attempts reaching a verifiable balloon altitude. That one may also have been successful, but transmission from the scientific instru­ment ceased early in the flight. Problems were encountered, however, with quite a few of the rockets and scientific instruments. There were four cases of failure of the igniters to fire. The instrument on another flight froze out before the rocket fired. And in three cases, the instruments failed after the rockets were fired, but before they reached usable altitude.

The final tally for the northward expedition included one fully successful flight out of five attempts with Larry’s magnetometers. Van Allen obtained useful data from the balloon phases of 11 of his 13 flights, but only 6 of those flights produced usable rocket phase data. In spite of those rather disappointing results, the expedition did provide important new scientific information, as outlined later.

The ship returned to its homeport at Norfolk on 20 August.

The IGY effort at the University of Iowa was a large one, putting considerable strain on the Physics Department. Funding was always a problem. By mid-September 1957, the situation had become especially critical. Van Allen met with Frank McDonald, Kinsey Anderson, Carl McIlwain, Larry Cahill, and me on 16 September to agree on programmatic changes to bring the endeavor within our overall IGY budget. That meeting produced a list of actions, the most notable being a reduction in the number of Cajun sounding rockets and in instrument development for Anderson’s program, a re­duction in the number of personnel to accompany the upcoming mid-Pacific/Antarctic expedition, and a reduction in the early 1958 schedule of Nike-Cajun firings. Those changes were accompanied by a general tightening of the effort within the laboratory to conserve resources, as well as several efforts to obtain additional funding.

And south to the Equator and Antarctic As soon as the Van Allen-Cahill team returned to Iowa City from the Arctic expedition, they began a frantic period of activity before departing southward less than five weeks later. The first order of business was to complete the instruments that were in the final stages of assembly and checkout.

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Larry and his team produced 20 instruments for the next voyage, of which 18 would be expended in flight attempts. With only minor exceptions, his instruments for the southbound expedition were identical to those flown on the Arctic expedition. He worked mightily during this short period to improve the troublesome tuning of the amplifiers in order to reduce their tendency to break into oscillation.

Don Goedeke and his helpers were working to complete the instruments for Van Allen’s flights, of which 17 would be launched. Nine of those 17 contained single GM counters for use at relatively low latitudes for the cosmic ray survey. The other eight contained the multiple counters described earlier, one relatively unshielded, and the other shielded by various amounts of aluminum or copper in order to search for and study the soft X-radiation in the southern auroral zone (in addition to continuing the latitude survey there).

Van Allen was heavily occupied during that period with coordinating the coming expedition’s efforts in Washington. In addition, he had his duties as head of the Physics Department as it entered the new semester and was busily engaged in his many planning and coordination duties for the IGY.

Both Van Allen and Cahill also rushed, during that short period, to complete papers being prepared for the upcoming CSAGI Conference on Rockets and Satellites that began on 30 September. They primed me to present their papers while they were on their expeditions.

In late September, Van Allen and Cahill departed from Iowa City with their instru­ments and laboratory equipment to join the ship at the Navy yard at Boston. The two constituted the entire Iowa contingent—the cost-cutting actions mentioned above excluded other helpers.

The ship was the USS Glacier, a new, larger, and highly improved class of Navy icebreaker.30 Navy Commander B. J. Lauff served as its commanding officer. Its primary mission was to cruise from Boston to the Antarctic at the beginning of Opera­tion Deepfreeze III. Agreement was reached for the icebreaker to support the rockoon expedition by deviating from its normal direct course from the Panama Canal to the Antarctic by first progressing nearly due west to the equatorial region south of Hawaii.

Throughout the expedition, the researchers were helped by another very competent liaison officer, Lieutenant Junior Grade Steven (Steve) Wilson. His primary assign­ment was to coordinate the research activities with the ship’s crew, but he also helped actively in preparing and launching the rockoons. He proved to be a tremendous asset—enthusiastic and interested—always wanting to know how everything worked.

The ship left Boston on 23 September. During the passage south toward the Panama Canal, the team launched two rockoons, being careful to stay well away from the normal shipping lanes. The first launch, made well out to sea from Georgia, without an operating payload, was a test flight to check out the launch procedures and rocket.

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The next day, well off the coast of Miami, they made their first research flight with one of Van Allen’s cosmic ray instruments. He was encouraged by that successful initial flight, unmindful of the later problems that were to beset him.

After transiting the Panama Canal near the end of September, the ship put in at Balboa, where it remained for several days. During that stay, in addition to helping with the shipboard preparations, Van Allen was very busy on the telephone, following up on expedition arrangements, on his various responsibilities for the IGY, and as head of the Iowa Physics Department.

Van Allen also continued to work with his instruments, which were proving to be even more troublesome than on the Arctic expedition. Larry recalled that, back in the Iowa laboratory during the summer, Don Goedeke appeared to be having problems in preparing them. Don’s many questions dealt with such elementary things as construction practices, transmitter tuning, etc. At the time, being heavily occupied with his own work, Larry didn’t realize how serious the problems were with the cosmic ray instruments. As it turned out, it was necessary for Van Allen, throughout the entire southward voyage, and assisted at times by Larry, to do “an awful lot of work to try to get some of them to work.”31

While in Panama, they loaded additional helium for the balloons. Somehow, in that process, Van Allen received a deep gash in his leg that proved to be a serious problem during the next few weeks.

Larry’s objective for the Arctic and Antarctic expeditions was a comprehensive in­vestigation of electrical currents in the ionosphere. An important part of that program was to look for, and measure, the equatorial electrojet, a current believed to be flowing in the ionosphere in the region of the equator. He decided that launches near the Line Islands south of Hawaii, specifically in the region between Christmas and Jarvis is­lands, would provide the best conditions for meaningful results. That was because the Earth’s geographic and geomagnetic equators intersect there, and the strongest indi­cation of the small change in the magnetic field would be measurable with his proton precession magnetometer. In addition, that was the location of a number of ground observatories, established as part of the IGY program, whose ground observations would help in interpreting his flight results.

The break at Panama provided an excellent opportunity for Larry Cahill to tweak his magnetometers. It happened that the magnetic field at Balboa was close enough to that expected at the planned equatorial launch site that he was able to tune the instruments there for optimum performance when launched.

The first of Van Allen’s two primary objectives was to continue the latitude survey of the primary cosmic rays. That called for launches of his counters from a wide variety of geographical locations, including measurements at the equator.

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Van Allen launched one of his single GM counter instruments during the morning of 4 October, soon after leaving Balboa, while the ship was somewhat north of the Galapagos Islands. That flight was encouraging, as it produced useful data from both the balloon and rocket phases. From that point on, things took a discouraging turn. The next weeks certainly must have been among the most frustrating and stressful of Van Allen’s life, for three reasons.

First, he continued to be beset by the many problems with his instruments. In spite of hard work throughout the rest of the expedition, he had very limited success in achieving fully successful rockoon flights. It was not until nearly a month later, after 10 more attempts, that he was able to achieve another successful high-altitude rockoon flight.

Second, on the day of his first Pacific launch, the world was ushered into a new era by the Soviet launch of the first artificial Earth satellite, Sputnik 1. And there was Van Allen, on a ship in the Pacific Ocean, essentially out of touch with all of the space – related action that he had helped set in motion through his vigorous participation in the planning and conduct of the IGY!

Both Van Allen and Cahill have described the excitement on the ship as word was received of the Soviet launch. The first announcement had been received in the United States from an Associated Press wire from Moscow at about 6:30 PM EST. The story of its announcement at the Soviet Embassy is related in Chapter 6. That announcement would have been at about 5:30 PM local time on the ship, and they received the news very promptly via Armed Forces Radio. Van Allen’s account, as recorded in his field notebook and quoted in his book Origins of Magnetospheric Physics, was as follows:

Yesterday night the 4th and early this morning were very exciting for me (as well as for the civilized world in general).

Just before dinner time Larry Cahill told me that news was just coming in on the ship’s news circuit that the Soviet Union had successfully launched a satellite [emphasis his]. Factual details as follows:

Inclination of orbit 65° to Earth’s equator. Diameter 58 cm. Weight 83.6 kilogram (Wow!). Estimated Height 900 kilometers (Perigee or Apogee?) Period 1h 35m.

Transmitted Signal: 20.005 Mc/sec and 40.002 Mc/sec with switching alternately from one to the other—spending about 0.3 sec on each frequency. Would pass over Moscow at 1:46 A. M. and at 6:22 A. M. on the 5th, Moscow time. (Moscow is -3, or rather +21 zone time from Greenwich.)

Our Ship’s Position ~5° 30′ N, 92° W (+6 zone time)

After dinner (and a very poor movie), I went up to the communications shack to see if there was any further news available (about 2120 Ship’s time (+6)). As I walked in to look at the teletype machine a young radioman (David Armbrust RM 3/c) wearing a pair of earphones and hovering over one of the ship’s communications receivers turned to me and said, “I think that I have it!” This was at 2120 (zonetime of October 4) or 0320 Z (Greenwich Time) of the 5th of October. I listened to the phones and heard a repetitive Beep-Beep-Beep-etc. of an audio frequency tone—loud and clear. The r. f. frequency was very nearly 20.005 Mc/sec. I had earlier considered using our Clarke receiver but recalled that 55 Mc/sec was [its] lowest

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frequency. Then I briefly considered the ship’s capabilities but (too hastily) discarded this possibility on the general impression that the signal would be quite weak ala U. S. plans and that the ship’s communications gear would be inadequate in basic noise level.

However, Mr. John Gniewek (with a B. A. in physics from Syracuse Univ.), young civilian employee of the U. S. Coast and Geodetic Survey, who was a passenger on the Glacier going to the Antarctic to operate a magnetometer station there for the coming year, had been up to the communications shack earlier and had inquired if they could receive it. Armbrust had started looking with first success at ~0320 Z. He had also run a receiver calibration and had been listening and searching assiduously for some minutes.

My first reaction was: Could it possibly be true that this was the satellite’s transmission? (Not a spurious effect of some kind—or something from WWV at 20.000 Mc/sec.)

At about this time Gniewek came up. He listened, also excitedly. It immediately occurred tome that we should make a recording! I thought of our Ampex [tape recorder] in the rockoon lab but was somewhat discouraged of hauling it up to the comm. shack because of its weight and the way in which it was “built-in” to Cahill’s apparatus! I remarked on this to Gniewek!

He immediately responded that he had a small magnetic tape recorder in his room, which he could easily bring up. I said fine! And rushed down to our rockoon lab to bring up my small Tektronix (Type 310) oscilloscope to look at the signal visually. I first noted the time as 0329 Z on the clock in the comm. shack. Within about 5 minutes, we were both in operation!32

Van’s detailed account described the scenario on the ship for the next several days as they continued to monitor the new satellite’s signals. Larry Cahill related his recollection of the event:

We heard about it on the radio. You know, the Navy had good radio contact with the fleet headquarters—their military directors. And also what was going on with the news. So we were informed, and everyone on the ship was. We heard the beep, beep, beep.33

As his third frustration, on 7 October, Van was laid low by a bad lymphatic infection from the gash in his leg. Even with excellent care by the ship’s doctor and another doctor, he was flat on his back in his bunk for much of the next nine days. During that time, the ship proceeded nearly 6000 miles to the neighborhood of the Line Islands.

Larry launched another of Van Allen’s rockoons for him on 13 October, when they were still nearly 1000 miles east of Christmas Island. Although that flight produced useful balloon altitude data, no higher-altitude rocket data were obtained due to either instrument or rocket failure.

As they neared the equator in the neighborhood of Christmas and Jarvis islands, the group’s emphasis shifted to Larry’s magnetometers. In that region, during the period 14 through 20 October, Larry made 10 rockoon launch attempts. Those launches ranged from about 7 degrees north to 2 degrees south geographic and geomagnetic latitude.

One of the launch attempts early in that series, made while Van Allen was still unable to assist, was marred by a rather scary incident. As Larry related it:

We started launching [magnetometer] rockoons from the helicopter deck on the stern of the

icebreaker as we approached Christmas Island, south of Hawaii. … We had filled the balloon

Special Publications 114

with sufficient helium and were ready to release it. By that time, the ship’s direction and speed should have been adjusted to be traveling with the wind, so that there was a zero wind over the launch deck. The balloon, tethered by a line to the rocket and payload, should be straight overhead, ready for release. Unfortunately, despite our instructions, the people on the bridge hadn’t got it quite right. The line to the balloon was trailing to the stern, at an angle of 45° to the vertical. In past flights, off Greenland, Professor Van Allen had been on the bridge to counsel the Navy people on how to obtain zero wind. He was confined to his bunk for this launch, however, after gashing his shin in a fall while we were loading helium cylinders in Panama. The wound had got infected and the ship’s doctor had required him to be completely immobile. Meanwhile, I was holding the rocket and attached firing mechanism box in my arms and was providing ballast to prevent the balloon from rising. I couldn’t release the rocket since it would surely swing and hit the deck or some other part of the ship before the balloon rose high enough. Zero wind was essential so the balloon and payload could go straight up. Steve Wilson took off for the bridge and I hung on as the balloon pulled me toward the stern. As the helmsman tried to adjust course the situation got worse; the angle increased to 60°. The tug of the balloon was considerable and I moved slowly toward the edge of the flight deck. By this time, the balloon had moved to the port side of the ship, but there seemed to be little progress toward zero wind. Standing at the edge of the flight deck and leaning backward to counteract the balloon tug, I felt somewhat uneasy. As several more minutes passed with no improvement in the angle, I began to consider releasing the rocket. From where I was standing, the rocket would swing out under the balloon as the balloon rose. It would not hit any part of the ship, but would the balloon rise fast enough so it wouldn’t hit the water? After several more minutes with no improvement, I released the rocket. The rocket swung in an arc toward the water. The balloon rose sluggishly and the firing box hit the water first. Next, a wave caught the bottom of the rocket and the balloon stopped rising. Eventually the inflated bubble of the balloon sat on the water as we moved away. We conducted a thorough seminar on achieving zero wind before the next launch.34

Much later, during an informal discussion of the event, Larry related:

If we had good coordination with the ship’s people, then we had [effectively] zero wind, but that didn’t obtain very often on that ship. Often it was the case that the balloon was off in some direction, and I was holding the damn rocket, because it was tugging me toward the edge of the deck, and finally had to let it go. In one case, the balloon wasn’t high enough, and the damn rocket swung down when I released it and went in the water, so that scratched that payload. It was very irritating. We explained this to the Navy people—they were a little grouchy—they weren’t entirely happy to have us on board. They weren’t awfully interested in what we were doing, if you can believe it. …

… We certainly impressed on them that we wanted the [tethered] balloon right up over the deck, because that would make our problem much easier. If he had done that, I could have left the payload down on the deck and let the balloon lift it off, but you couldn’t. So I had to take it up, and I wasn’t too crazy to do that, because if the thing went off, it would have sliced my arms off. But I did it.35

The record of performance for Larry’s equatorial launches was mixed. The available papers make no mention of results from 4 of the 10 attempts, so it is presumed that they resulted in either poor instrument performance or rocket failure. In two other cases, the rockets fired but the data were very limited. In another case, the rocket fired at a low zenith angle, resulting in a low peak altitude and limited data.

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The other three launches (on 17, 18, and 19 October) were fully successful. Al­though a greater number of successful flights would have been welcome, those three did make a major contribution toward understanding the equatorial electrojet.

After completing their work at the equator, the emphasis shifted again. Larry’s pro­gram did not call for another flight until they reached about 65 degrees south latitude, the region of the large plateau on the isomagnetic charts where they might be able to detect the effects of any polar cap current.

Van Allen was well enough by then to resume his launches. He made his next attempt on 18 October very near the equator. Although the launch produced good balloon data, no usable rocket phase data were received. During the next days, he spaced a sequence of launch attempts with his single GM counter instrument along the ship’s course at about 3 degrees, 7 degrees, 18 degrees, 39 degrees, and 40 degrees south latitude. Four of those five attempts resulted in usable balloon data, but, with mounting frustration, rocket data were not obtained from any of them.

At that point, they were approaching the southern auroral zone, and Van Allen switched to his second objective, to try to characterize the soft auroral radiation. As they passed from about 40 degrees to 70 degrees south latitude, he launched three of those instruments, of which two reached useful balloon altitude. None, however, produced usable data from the rocket phase.

It was on 30 October, just as they were approaching Antarctica, that Van Allen received the first of a series of unclear and somewhat mystifying messages on another subject. They involved the shifting of the Earth satellite instrument that I was building at Iowa from the Vanguard program to the Jupiter C launch vehicle. Because of the classified nature of the new program, those messages were intentionally convoluted, and he was not able to fully understand their intent until after he reached port in New Zealand 10 days later. He was finally able to clarify the situation during the first few days in New Zealand, and he wired his final approval for the change in the Iowa program on 13 November. The story of that exchange of messages and the decision and resulting actions are detailed in Chapter 8.

By then, the ship was off Cape Adair on the coast of Antarctica, in the Ross Sea north of the Ross Ice Shelf. It remained in that general area from 30 October to 5 November. Van Allen launched three more of his soft auroral radiation instruments there (Figure 4.6). All three produced good balloon data, and one finally yielded good rocket data. Also while there, Cahill launched eight more of his magnetometers, of which three produced good data throughout their flights.

They left the Ross Sea on 5 November, headed for New Zealand. During that passage, Van Allen made two more launches of his cosmic ray-auroral instrument, of which both produced fully useful balloon and rocket data.

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The ship reached Port Lyttleton, near Christchurch, New Zealand, on 10 November. Van Allen and Cahill buttoned up their operation there and made their way home, finally arriving at Iowa City on 23 November 1957, in time for Thanksgiving.

By the time they reached New Zealand, nearly all arrangements for shifting our satellite experiment to the Jupiter C had been completed; I was poised to leave for the Jet Propulsion Laboratory (JPL) in Pasadena, California, with our cosmic ray instrument designs and prototype as soon as Van Allen gave his approval. I was already actively working with the JPL engineers to adapt it for flight on the Jupiter C launch vehicle.

Expedition results Larry Cahill’s Ph. D. dissertation contained an outstandingly lucid discussion of the entire proton free-precession magnetometer program, from the objectives to development of the instrument, description of the field program, and interpretation and publication of the results.36 The effort represents an impressive example of a highly advanced research project carried out from start to finish by a talented graduate student under the general guidance of an outstanding leader. That environment, seen in action repeatedly over those years, helped propel Van Allen’s group at the University of Iowa into such effective leadership in the early space program and thereafter.

Larry’s first successful flight in the North Polar Region verified, for the first time by direct measurement, the existence of the previously hypothesized north polar cap ionospheric current. In addition, he measured its height (centered at about 70 miles) and obtained estimates of its direction, current density, and vertical extent.

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Even with three successful flights in the southern polar area, the corresponding current was not observed there, perhaps due to problems in interpreting the data and/or to the fact that the flights simply did not happen to be where the current was located at the particular time.

The results from Larry Cahill’s flights in the equatorial zone began to emerge in early 1958. On 7 January, Van Allen penned a note to me at JPL giving initial results from two of those equatorial flights. He wrote, “Larry Cahill has two of his equatorial flights reduced. One, near 0° latitude, shows a beautiful discontinuity of ~100y [about 100 gammas of magnetic field strength] in a 10 km. altitude range (100-110 km.) and a further discontinuity above 115 km. The other at ~3° 23" N shows a [undecipherable word] (~30y) [undecipherable word] at about the same altitude as would be expected from passing through a ‘filament’ of current.”

Larry thus confirmed the existence of the equatorial electrojet current in the lower ionosphere by the first-ever direct measurement. He determined its height and current density at several latitudes near the equator during both periods of magnetic calm and a moderate disturbance. His most exciting finding was the discovery of a second equatorial current layer slightly above the main electrojet current. That result was entirely unexpected, and although some of the theoreticians questioned it initially, its existence was eventually widely accepted.

The third result from Larry’s expedition was the measurement of the rates of decrease with altitude of the Earth’s main magnetic field at three locations. They were compared with the rate of decrease that would be seen if the Earth’s field were a simple dipole, where the inverse cube law would rigorously apply. He found that the main field in the Davis Strait falls off less rapidly than that of a dipole, while in the Antarctic, it falls off more rapidly. In the equatorial region, the field also falls off more rapidly than that of a simple dipole.

Van Allen was completely absorbed upon his return to Iowa City by the many demands on his time by the rapidly evolving space program. Much later (in 1994-1995), he returned to the original records of the 1957 expeditions to make a full reduction of the data and publish the results. In the first of those reports, he treated the entire body of data resulting from a total of 26 balloon flights ranging from 86 degrees north to 73 degrees south geomagnetic latitude. Values of the omnidirectional cosmic ray intensity were plotted as a function of geomagnetic latitude for four heights: 6.25,7.8, 9.4, and 12.5 miles. Those values represent a still-unique representation of the cosmic ray intensity at those heights during a period of maximum solar activity. He compared the values with those obtained during the Iowa expedition in 1953, a period of relative solar inactivity, and found that the cosmic ray intensity at the solar maximum was lower than its value near the solar minimum. The 1957 value was about 30 percent less than in 1953.37

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He also read and evaluated the GM counter data from the 10 flights during which the combination of balloons and rockets achieved useful peak altitudes, and usable data were recovered. Those peak altitudes ranged from 48 to over 81 miles. Six of those successful flights were made in the north auroral zone (from 66 degrees to 86 degrees north geomagnetic latitude), one in the region of the equator (16 de­grees north geomagnetic latitude), and three in the south auroral zone (52 degrees to 72 degrees south geomagnetic latitude). The soft auroral radiation (which by that time was being referred to regularly as auroral bremsstrahlung due to electrons interacting in the atmosphere and instruments) was detected in eight of the nine high-latitude flights. From differences in the shielding provided on the various coun­ters, he derived values for the spectrum and energy flux of the primary auroral electrons.38

Other rockoon efforts To complete the rockoon picture, the development of a rockoon capability was undertaken in several other arenas.

Rockoons in Japan Japanese scientists announced their intent to examine the launching of rockoons at the fourth meeting of the CSAGI at Barcelona on 10­15 September 1956.39 A later disclosure stated that “the Sigma project aims to develop a Rockoon, like that pioneered by J. A. Van Allen. A small rocket of about 25 lb. will be used, and a peak altitude of between 55 and 65 miles (90 and 100 km), with a payload of 5 lb, will be sought.”40 The Japanese program is mentioned again in the IGY Manual on Rockets and Satellites. That discussion includes the statement, “Preparatory experiments for the study of the balloon launching tech­nique from a ship and from the ground, temperature change of the fuel during the balloon flight, barometric relay for the automatic firing at the altitude of 20 km, telemetry, etc. have been carried out in April, June, and July 1957.”41 An oblique mention of the Japanese rockoons is contained in a later volume of the IGY Annals. It simply states that “a total of 80 rockets and rockoons will be launched during the IGY.”42

Although preliminary tests were conducted using dummy rockets, no Sigma launchings are listed among the compilations of IGY rocket flights, and it is con­cluded that the operational program was never accomplished.

Australia A few references to an Australian interest in rockoon launching were found. In a discussion of their Woomera rocket launch site, it was mentioned that “Skylark, the British sounding rocket, and Rockoons are being launched at Woomera for the IGY program.”43 A slightly more illuminating allusion to a rockoon program is contained in volume 6 of the IGY Annals, with the paragraph, “In collaboration with the Upper Atmosphere Research Committee of the Australian Academy of Science, the Australian Department of Supply intends to carry out a program of high

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altitude research during the IGY using the ‘rockoon technique.’ A large hydrogen – filled polyethylene balloon (manufactured by the University of Bristol, England) lifts the rocket vehicle to its launching altitude of between 30,000 and 40,000 ft; the rocket, which carries 50 lb weight of instrumentation, is then fired by means of a radio link. It is expected that peak altitudes in excess of 300,000 ft will be attained.” That reference identified the project as the High Altitude Research Project (HARP) and included a picture of a HARP launch from Woomera and a tabulation of expected performance parameters.44

No HARP launchings are listed in the compilations of IGY rocket flights. Appar­ently, the program never progressed beyond the testing phase.

The L5 Society The Huntsville, Alabama, L5 Society (HAL5), a chapter of the National Space Society, initiated a program for launching rockoons in 1994. The project was called High Altitude Lift-Off (HALO). Its stated purpose was “to provide

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cheap access to space for high school and college students, small clubs, even scientific researchers.”45

Their first launch, Sky Launch 1 (SL-1), was from Hampstead, North Carolina, on 11 May 1997. The primary payload was a video camera. The estimated peak altitude was about 44 miles. A second flight (SL-2) from a barge 60 miles southeast of New Orleans, Louisiana, was scheduled for 20 June 1998, again with a video camera. No record could be located of its actual flight or of any other later project activity.

Rockoon summary An Internet search revealed no other evidence of rockoon flights for scientific research. Evidence could not be found to indicate that other than a few test flights were made by any group other than the University of Iowa and the NRL. The use of rockoons by NRL ended in July 1956 and at Iowa in November 1957.

A tally of all known rockoon launches is shown in Table 4.1. A total of 139 rockoon launch attempts were made. One hundred and nine of those were made by the University of Iowa, and the other 30 were by the NRL.46 Of the 109 Iowa launch attempts, about 80 percent provided good data from the balloon ascent phase, and about 50 percent provided good data from both the balloon and rocket phases.

When the army’s Orbiter proposal was formally submitted to Assistant Secretary of Defense Donald Quarles on 20 January 1955, he set up an eight-member committee to

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study and recommend which satellite proposal should be accepted.15 Its membership consisted of the following:

Stewart, Homer J. C. (Chair) California Institute of Technology/JPL Clement, George H. RAND Corporation

	University of Buffalo U. S. National Committee for the IGY California Institute of Technology University of Michigan General Electric Co. Missile Division Cornell University

The committee was instructed to bear in mind that noninterference with ballistic missile development was essential. They were further instructed that the satellite program was to be a purely scientific rather than a politically motivated program. That undoubtedly led to the committee placing much more emphasis on the scientific results than on early launches.

An early action of the Stewart Committee was to eliminate the Atlas option as potentially taking too long and possibly delaying the development of the military long-range atomic bomb-carrying capability. The committee then set about the task of comparing the Orbiter and Vanguard proposals.

It certainly cannot be claimed that the committee rushed to a snap judgment. In late June, a subgroup made a field trip to JPL and the air force’s Western Development Division. The full committee met on 6-9 July 1955 for an extended set of briefings and a visit to the Glenn L. Martin plant to see the work layout of the Viking rocket. They met from 20-23 July to generate a second draft report, and on July 29, three of the members met with Quarles to discuss a third draft.

Even while the Stewart Committee was hammering out its assessment and rec­ommendation, President Eisenhower, on 27 July, agreed to publicly announce the U. S. satellite program, and did so two days later. Making the announcement before receiving the Stewart Committee report reflected the perceived urgency of the sit­uation. Intelligence reports suggested that further postponement of the news would risk having the USSR make their satellite announcement first. In fact, the Soviets, prompted by Eisenhower’s announcement, did reveal their plans to put a satellite into orbit in the Moscow press just four days later.

Their July deliberations left the Stewart Committee members divided. They met on 3 August to prepare their formal recommendations. That meeting took place without McMath, who was ill at the time. Of the seven voting members attending that meeting, three were in favor of the Vanguard, while two preferred the Orbiter. The other two, explaining that they were not guided missile experts, stated later that they simply went along with the numerical majority. Thus, the vote came out in favor

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of the Vanguard program. McMath later made it very clear that had he been present, he would have voted for the Orbiter. That would have resulted in a tie vote by the knowledgeable experts, perhaps changing the vote by one or both of the others. As pure speculation, McMath’s presence might have changed the outcome of the Vanguard decision.

Over the years, many factors have been mentioned as having influencing the decision.

This brief summarization discusses the most prominent ones in no particular order.

• Early proposals asserted that the Vanguard would lift heavier payloads into higher orbits.

The comparison is somewhat confused in many accounts, where different items of hardware were contrasted. In the Vanguard program, the instrumented satellite package was separated from the final rocket stage in orbit. In the Jupiter C proposal, the instrument package and final rocket stage remained attached to each other. So if one compares the items that formed the active satellite bodies, the Vanguard II weight (instrumented sphere minus the final stage rocket) was about 24 pounds versus about 30 pounds for Explorer III (instrumented cylinder plus the depleted final rocket stage). However, the total weight carried to orbit for Vanguard was 71.5 pounds (23.7 pounds for the instrumented sphere and 47.8 pounds for the empty rocket case). That contrasts with the 30 pound Explorer III weight that included the 18.5 pound instrument package plus the 11.5 pound final rocket casing.

Vanguard did, in fact, place its satellites in substantially higher orbits. The Vanguard II orbit parameters were 1952 miles apogee and 347 miles perigee, while the comparable Explorer III parameters were 1740 and 119 miles, respec­tively.

• It was asserted that Vanguard had a greater growth potential for heavier payloads in the future.

Heavier versions of both vehicles were eventually flown. Vanguard III (TV – 4BU) was launched on 18 September 1959 with an improved final rocket stage. That version placed about 95 pounds in orbit (52.3 pounds for the instrumented satellite plus 42.3 pounds for the empty final rocket stage). Its orbital parameters were 2190 miles apogee and 319 miles perigee. That represented the end of the path for the practicable evolution of the Vanguard vehicle.

The substitution of the Jupiter IRBM for the Redstone rocket as the first-stage rocket to form the Juno II configuration gave the army an increased payload capability for Earth orbit, and a capability for reaching Earth-escape velocity. The launch vehicle for Explorer 8 placed about 102 pounds in orbit (89.9 pounds

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for the instrumented satellite and about 12 pounds for the separated final rocket stage). Its apogee and perigee heights were 1056 and 253 miles, respectively.

• Early cost estimates indicated that the Vanguard program would be less expensive than the Orbiter program.

The Vanguard costs turned out to be much higher than early projections, while the Orbiter/Jupiter C cost was closer to its projection. But a meaningful final cost comparison is probably not possible, as the Jupiter C development made heavy use of hardware left over from the RTV program, while most of the Vanguard development and procurement (with the exception of two Viking rockets left over from the sounding rocket program) was for new hardware.

• Both adherents asserted that the state of their developmental efforts was well advanced.

The developmental work to complete the Vanguard vehicle was much more complex and troublesome than anticipated, and unanticipated problems with the contractor developed, thus causing many protracted delays. The first successful launch of a Vanguard test payload was not made until 17 March 1958, five months after Sputnik 1 was launched, and a year and a half after the successful test firing of the army’s three-stage RTV The first successful launch of a Vanguard payload withafull scientific package (Vanguard II) did not occur until 17February 1959, over a year after the Explorer I launch, and after the end of the IGY.

The modification of the Jupiter C, on the other hand, was much further advanced and simpler, so that it was possible to make a quick response once the army was given the go-ahead.

• The Vanguard proposal included detailed information about the problems of satellite tracking and orbit determination, while the Orbiter proposal was com­paratively lacking in that area.

• The NRL was highly experienced in building and launching miniature scientific instrumentation, while the army group lacked that experience.

The NRL experience began with the preparation of rocket payloads for the V-2 launches during the postwar 1940s and continued with the development of instruments for the Aerobee, Aerobee-Hi, and Viking sounding rockets, among others. They had a formidable in-house capability and an excellent record of facilitating the use of research instruments by university and other institutional research groups. In other words, they were well established within the upper – atmosphere research community.

The Huntsville group had experience with launching scientific payloads with their V-2 rockets at White Sands, but they were not experienced in constructing those instruments and were not nearly as well known within the scientific research community.

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• Those conducting the military rocket programs in all three services were un­der tremendous pressure to deploy IRBMs and ICBMs as quickly as possible, following the Soviet demonstration of a nuclear bomb-delivering capability. The navy’s Vanguard program was more thoroughly decoupled from military rocket development than were the army and air force plans. Therefore, awarding the program to NRL was expected to cause the least disruption to the nation’s military programs.

Possible additional factors have been mentioned during the intervening years. For example, it has been suggested that there may have been antipathy to having “those German V-2 designers” lead the American satellite program. Although that might possibly have been true within some circles, I saw no evidence for it within my circle of associates. Although not involved in the Orbiter/Vanguard decision-making process, I did work closely throughout the 1955-1960 period with many of the scientists and engineers in the Vanguard program, with U. S. IGY program officials, and, of course, with the Huntsville and JPL technicians, engineers, scientists, and managers. In all of my contacts, there was a consistent overriding concern with simply getting on with the challenge of entering the new space arena. Never did I hear any indication that prejudice against the German group had been a significant factor in the decision in favor of the Vanguard.16

It has also been suggested that the decision might have been unduly influenced by the fact that one of the most influential of the Stewart Committee members, Richard Porter, worked for the General Electric Company, which was responsible for building the Vanguard engines. Countering that argument, Homer Stewart was closely aligned with the Orbiter program through his work at JPL. The fact of the matter is that it would have been impossible to assemble a committee of individuals who were sufficiently knowledgeable about rocketry to make a sound judgment, but where no one was aligned with any of the companies involved in the technical programs. Although it will be forever impossible to know the private motivations of the individuals involved, I never detected any hint that the issue of vested interests might have been a factor in the decision, either pro or con.

Van Allen once gave his interpretation of the reasoning behind the Vanguard deci­sion as being “military-political in nature—to avoid revealing the propulsive capabil­ity of the United States and to avoid alarming foreign nations with the realization that a U. S. satellite was flying over their territories.”17 All evidence supports Van Allen’s assertion. At least in the pre-Sputnik military and intelligence-gathering thinking, one of the main objectives of the U. S. IGY satellite program was to establish the basic principle of “freedom of space.” That was deemed essential, among other reasons, in order to prepare the way for the United States to operate future intelligence-gathering reconnaissance satellites without precipitating “space warfare.”

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Programmatic speed was secondary to maintaining a strong nonmilitary flavor. Thomas A. Heppenheimer later summarized:

[Von Braun’s] satellite would have Army written all over it. His project center would be Redstone Arsenal, the chemical warfare plant that had become a facility for military rockets.

His booster, the Redstone, was a weapon in its own right, able to carry the atomic bomb. Against this nakedly bellicose background, the IGY would represent too thin a veil. The world would see von Braun’s satellite as a mere prelude to an invasion of space by military force.

But Milton Rosen’s proposal was something else entirely. His booster would derive from Viking and Aerobee, which had become known as research rockets launched for scientific purposes. The Naval Research Laboratory, which would serve as the project center, didn’t have the gamy reputation of Redstone Arsenal. It was known as a true center of research, with well-regarded scientists who had made important contributions in their fields.18

It was stated at one point that the ideal arrangement might be to combine the army rocket capability with the navy tracking and instrumentation capability, as had been planned earlier for Orbiter. But by the time of the Stewart Committee deliberations, it was clear that that arrangement was highly impractical because of the interservice rivalries that were by then rampant.

It is clear, certainly in hindsight, that one crucial element of the decision had not been given sufficient weight, even though some of the committee members and others believed it strongly. The assembly of the Viking, Aerobee-Hi, and solid-fueled third stage into a smoothly functioning whole was far more difficult than originally envisioned by the Vanguard team.

It should be remembered that the Vanguard program was, in the final analysis, a fully successful one in terms of its originally stated objectives. During the IGY, it placed a satellite into a durable orbit, proved by suitable tracking that it was there, and used it to conduct a scientific experiment. Vanguard I, launched on 17 March 1958, had such a high orbit that it is still circling the Earth 50 years later, and will continue to do so for many years to come. The Minitrack system worked perfectly in tracking the satellite and recovering its data, and the Moonwatch program provided high-quality optical tracking. It performed passive experiments by determining the Earth’s shape from long-term tracking of the orbit, and that the Earth’s atmosphere was far more extensive and variable in extent than previously believed. Vanguard II, launched on 17 February 1959, contained a major active scientific instrument—the Stroud cloud cover experiment. And on 18 September 1959, Vanguard III carried a suite of magnetometer, X-ray, and environmental instruments.

It is unfortunate for Vanguard that the Soviet launch of Sputniks 1 and 2 completely changed the rules of the game. Before that, the United States was moving along deliberately but steadily with the development of a complex new and essentially nonmilitary system, attuned to meeting its goals by the end of 1958. The satellite

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program was clearly given a lower priority than the military rocket development programs. Having the Soviets beat us into orbit immediately subjected the space endeavor to a different set of rules. The public perceived the Soviet accomplishment as a demonstration of the superiority of their technology, and they clamored for a quick demonstration that we were not lacking in that regard. The space program instantly became a major factor in the ongoing U. S.-USSR cold war.

The army’s program was quickly approved after the first two Sputnik launches as a backup to the Vanguard. Using what by that time was a well-tested primary launch vehicle, coupled with continuing bad luck for the Vanguard program and a wealth of good luck for the army, the first Explorer was launched before the first Vanguard could be orbited.

In retrospect, probably the Vanguard program’s biggest mistake was in responding to the pressure of the Sputniks by billing their December vehicle test as a major effort by the United States to join the Soviets in space. The spectacular failure on 6 December subjected the United States, and the Vanguard program, to public and international humiliation and ridicule. The Vanguard program was never able to overcome that state of affairs.

The Vanguard program had many important lasting effects on the burgeoning U. S. space program. Many of its planning and oversight methodologies and capabilities served as the model for NASA after its formation. In reality, the overall Vanguard program served as one of the major starting points for the entire fabric of U. S. scientific satellite program formulation and management.

The Vanguard launch vehicle was designed and developed in 30 months, a time that is remarkable by any standards. It was highly efficient and otherwise technically remarkable. The use of unsymmetrical dimethylhydrazine as the fuel in the Aerobee – derived second stage vehicle was a significant new departure, as was much of the design of that stage. The air force later used that design in their series of Thor-Able boosters. The fiberglass-encased third-stage rocket in Vanguard III was a pioneering development that contributed to the later success of the Scout launch vehicles. The “strapped-down” gyroscope platform, the rotatable exhaust jets of the first stage turbo pump, and the C-band radar beacon antenna, all of which originated with Vanguard, were employed in other later rockets.

The Minitrack network of ground tracking and data receiving stations supported all early satellite launches, and provided tracking and orbital data recovery for them. The value of the army’s Explorer I would have been greatly diminished without the coverage they provided from the wide-ranging array along the North American east coast and South American west coast. Explorer III depended on them exclusively for recovering the data from its onboard tape recorder. Their tracking data, coupled with

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the Vanguard orbit computational capability, served as the primary source of early satellite positional information. When NASA was formed in the fall of 1958, the Minitrack facilities became the nucleus of NASA’s ground network for Earth orbiting satellites. Likewise, the Vanguard data processing center evolved into the early NASA orbit determination and data-processing capabilities.

The satellite hardware design and fabrication capabilities, too, were remarkable. The entire later space program benefited from the Vanguard efforts in designing highly reliable, small, and low-powered circuits and components. Many of the Vanguard personnel joined the Goddard Space Flight Center when it was formed in the fall of 1958, carrying with them their expertise in building, testing, and launching both the primary satellite structures and the scientific instruments housed in them. Their long­standing experience with scientific experiments dating back to the post-WWII days with the V-2 rockets put them into a unique position to lead an energetic program of scientific discovery at Goddard, and to work effectively with scientists in other institutions, including the universities. The legacy of those pioneers is still evident today.

The next day, Friday, 31 January, the ABMA and JPL launch crews assembled once again in the blockhouse and other Deal operational sites, and I again joined Roger and Marty in Hangar S. Time was running out, as the days during which the satellite could be launched were waning. In the terminology of modern space-speak, the launch window was closing.

All was ready. The rocket, shrouded by the servicing gantry and illuminated by the floodlights, as shown in Figure 9.1, looked beautiful in the early evening. As the

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countdown progressed, the gantry was moved back to reveal the complete Jupiter C launch vehicle, with its diminutive fourth stage and satellite payload on its very tip. The assembly, with much of the Redstone rocket coated in frost due to the cold liquid oxygen in its oxidizer tank, and with the upper stage tub spinning, was shown earlier in Figure 0.1, which was snapped within the last 15 minutes before liftoff.

A word about the marking on the side of the Redstone booster rocket—“UE.” It was the custom at Huntsville to number the Redstone rockets in the order that contracts were issued for their manufacture. The key for the number coding was the word HUNTSVILLE. This was Missile 29. The second and ninth unique letters in the key word are U and E. Those letters are clearly visible in both Figures 0.1 and 9.1.

Not being in an active Deal project launch facility, I had access to only the general announcements being made over the Cape-wide public address system. That did not provide detailed coverage of the countdown progress. Von Braun, however, at his location in the Pentagon operations center, was in continuous telephone contact with the launch director in the Cape Canaveral blockhouse. He later recalled several exciting moments in the countdown. At one point, someone saw something dripping from the rocket. Albert Zeiler, the firing team’s propulsion man, crawled head down into the tail to investigate. Fortunately, it was just a spill, and he wiped it up.

There was a second hold a little later to investigate an anomalous reading on one of the rudders, but that was found to be an instrumentation error, and the count quickly proceeded. Finally, at 10:45, the moment came, and launch director Kurt Debus gave the word to start the firing sequence. At 10:48:16, the rising rocket opened the switch denoting liftoff, and the flight was under way.

After 156 seconds, when the rocket was 60 miles up, the booster rocket burned the last of its fuel and shut down. The spinning stages 2, 3, and 4 (with its satellite payload) coasted on toward the desired orbital altitude. During that climb, a special control system tilted the cluster so that at the apex of its flight, it would be pointed parallel to the Earth’s surface.

At that moment, Ernst Stuhlinger sent a radio signal for stage 2 to fire. Stages 3 and 4 then fired in sequence, boosting the speed of the final stage with its satellite to the critical 18,000 miles per hour.

His account continued, telling of the initial joyful reaction of the people gathered at the Pentagon and their haste to “tell the world.” But they decided to wait until a full orbit was confirmed, so they could be absolutely certain.2

From my post with Roger Easton and Marty Votaw in Hangar S, at 9:31 PM EST, I began logging the times of the transitions between two telemetered tones, as I had for the previous countdown attempt. At the beginning of that log, the vehicle count was

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at L minus 62 minutes and counting. As von Braun related above, there was a hold, which I recorded as happening at 9:48. The count resumed at 10:03. It proceeded smoothly until about 12 minutes before ignition, when a monitoring signal in the first rocket stage indicated something erratic about one of its control vanes. Members of the firing team concluded that the indicator was erratic and quickly resumed the countdown.

My notes during the last part of that countdown read:

Start spin-up at 10:37:36.

Modulation of carrier with spin at 10:38:10

L – 5 [minutes] at 10:43:09.

L – 80 seconds at 10:46:53.

L – 30 seconds at 10:47:53.

Fire at about 10:47:56 [EST].

Lift-off about 15 seconds later.

Counting rate increased rapidly.

Injection about 10:55:06. Signal was received for about 10 minutes (620 seconds) and counting rate sounded like it held steady all this time.3

Activity in the blockhouse and other control facilities is intense throughout any countdown and launch, as thousands of pieces of apparatus must be put into play and thoroughly checked.4 The Redstone booster in the Jupiter C configuration was the largest and most impressive part of the assembly. The task of that 56 foot long, six foot diameter, five ton rocket was to lift the payload and upper stages to orbital height. There the three upper rocket stages took over to accelerate its payload to the speed required for it to remain in a stable orbit.

Those three upper stages were arrayed in a tublike assembly, consisting of a second stage of 11 JPL rockets arranged in a circle around the outside circumference of the tub, a third stage of three of those same rockets arranged in a circle inside the outer ring, and a central final rocket stage with its attached satellite payload. Each of those 15 identical rockets was 40 inches long, about six inches in diameter, and weighed about 50 pounds when loaded.

About 17 minutes before booster ignition, an electric motor and chain drive started rotating the tub containing the three upper stages. It spun up quickly to about 450 revolutions per minute. During the burning of the Redstone booster, that speed was increased to about 750 revolutions per minute. The booster burned out 156 seconds after ignition, at a height of about 45 miles and at a speed of about 3000 miles per hour. The entire assembly then coasted upward for about 240 seconds to the apex of its trajectory at about 220 miles height. During that coasting period, the control system in the booster rocket pointed the complete assembly in the correct direction. At the proper moment, a signal from the ground initiated separation and second-stage firing. The spinning of the upper stage tub stabilized its alignment, much as a bullet is stabilized by its spin.

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The problem of determining the exact moment for injection was described earlier. Ernst Stuhlinger, backed by Walter Haeussermann, monitored an array of instruments as the rocket lifted through the atmosphere. They made a running calculation based on data telemetered from the Redstone booster and set several inputs into Ernst’s apex predictor. As the rocket neared its highest point, Ernst pushed a button that was in parallel with the predictor’s contact closure. That initiated ignition of the second stage. Postanalysis revealed that his timing was impeccable. Ernst has been known by his colleagues ever since as “the man with the golden finger.”

In response to Ernst’s command, a battery in the vehicle sent a current through an igniter; the heat of the igniter touched off a chemical reaction that lit a tiny amount of photographic flash power, and then, by a chain reaction, a larger amount. In a split second, the ring of 11 rockets forming the second stage roared to life, blasting the cluster away from the Redstone booster rocket. During the burning time of only six seconds, the second stage boosted the assembly to a new high in speed. A brief instant later, an automatic timing mechanism fired the third stage of three rockets, pushing it away from the second stage. After a similar six second burn, the third stage had done its work, and a few moments later, the timer ignited the final rocket stage, with its satellite payload. That final stage propelled the assembly to the required speed of over 18,000 miles per hour.

That was my first exposure to the launching of a large rocket. The initial sound of the thundering Redstone rocket took about 10 seconds to reach me across the approxi­mately two mile distance from the launch pad. When it arrived, it was overpowering—I felt as though it was trying to pound me into the floor. I recall that the noise had an unexpected crackling sound, signifying loud mid – and high-frequency components superimposed on the low-frequency thunder. The live sound is quite different from the sound one hears over the radio and television, where both the very lowest rumble and the highest frequency components are attenuated.

It took several minutes for the sound to fade as the rocket lifted and quickly gained speed. As it did, we were left with the sound of the cosmic ray instrument’s signal coming from the loudspeaker.

As mentioned before, each 32 counts of the GM counter was marked by the switching of the tone between two audio frequencies. With great satisfaction, I noted that the counting rate increased quite rapidly at first, reached a peak value, and then decreased to an essentially constant rate. It continued at that rate until the signal faded after about 10 minutes, when the departing instrument began to drop below our visible horizon. Later, after the initial ground station tapes had been processed at Iowa, the data from the JPL Microlock station at Cape Canaveral were plotted to display the information graphically. That plot is reproduced here as Figure 9.2.5,6

That pattern in the counting rate during ascent was exactly as expected. When the GM counter was low in the atmosphere, it was detecting mostly showers of secondary particles produced by the collisions of high-energy cosmic rays with atoms and molecules high in the Earth’s atmosphere. As the instrument rose higher, it detected an increasing number of those secondary particles as the region of primary interaction was approached, and also began to see some of the primary cosmic ray particles before they had an opportunity to interact in the air. Even higher, and the number of secondary particles decreased as the sensible atmosphere was left behind, and soon only the primary cosmic rays were seen. The combined effect resulted in a peak in the counting rate in the neighborhood of 11 miles altitude—it was the Pfotzer-Regener maximum mentioned earlier. Above that peak, the GM counting rate remained essentially constant as the instrument rose to orbital altitude. This can be seen graphically in Figure 9.2.

The gratifying conclusion was that the instrument had remained well above 11 miles altitude until after the vehicle had passed out of receiving range. Furthermore, it was clear that the instrument and telemetry system were operating properly.

Excited verbal confirmations of post-liftoff events were announced over the Cape intercom loudspeaker. First, there were reports via range instrumentation and missile telemetry receiving stations that the ignition and burnout of all stages had been normal, that separation of each of the stages had occurred on time, and that each stage had accelerated as planned. Then there was the report of the fading of the signal from

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the Patrick Air Force Base (PAFB) Microlock station at about the same time that we lost it in the Vanguard hangar, both occurring at the expected time. About two minutes after injection, the downrange station at Antigua, British West Indies, reported that the satellite had passed overhead. Finally, there was the somewhat-delayed report from the Cape’s Doppler velocity-measuring station that the payload’s speed relative to the launch site had been within the expected range as it departed over the horizon.

The Doppler measurements, however, yielded only single-axis velocities, i. e., ve­locities along the paths connecting the rocket and the ranging stations. In the absence of cross-track information, there was no way to know whether the final rocket stage had been pointed correctly, or somewhat up, down, right, or left. Misalignment could have resulted in failure to orbit.

The information received to that point produced an immediate feeling of jubilation. However, we would not know that the payload was actually in orbit until it completed a major portion of its first orbit.

After the loss of signal by the Antigua down-range station, there was nothing fur­ther that I could do at the Vanguard receiving station, as that site was not con­nected to the internal Deal communications network. I quickly made my way to JPL’s Microlock receiving station for further news. That station had been assembled in a trailer at JPL’s Pasadena facilities, transported to Cape Canaveral, and set up in an open area. Its primary purpose was to assist in checking the instrumented payload before and during the countdown. It was also used as one of the ground receiving stations for routine reception of the satellite signal throughout the satellite’s operating lifetime.

At that time, however, it had a special value—it was connected to JPL and the rest of the ground receiving station network by high-quality telephone lines. That provided access to the information being exchanged between the myriad control centers and receiving stations. I joined a small knot of individuals clustered outside the trailer’s entry steps. We did not really expect to hear of further signals from the satellite until it approached the Microlock and Minitrack receiving stations in California near the end of its first orbit. If the orbit had been as planned, with about a 105 minute orbital period, it should approach California a little more than 96 minutes after liftoff, or at between 25 and 30 minutes past midnight EST.

During the middle of the interminable wait for its arrival at the West Coast, Al Hibbs did appear at the trailer door at about 11:25 to relay some very limited but encouraging information about the initial satellite orbit prediction, based primarily on calculations done with the Cape Canaveral and downrange radar and Doppler data.

Although it has been variously stated that a few verbal reports came in during the first orbit from a scattering of amateur radio stations, no durable record of those

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contacts has been found. In any event, there were certainly no contacts before it neared the U. S. West Coast sufficient to establish whether the satellite was or was not in orbit.

Three Microlock stations had been set up in California. They consisted of the developmental installation at the JPL central laboratory in north Pasadena, a station established with JPL assistance by the San Gabriel Amateur Radio Club at Temple City east of Pasadena, and the station that had been set up for engineering tests of the Microlock system. That station was located in Earthquake Valley, near the town of Julian, about 30 miles northeast of San Diego.

The Vanguard project also had established one of their Minitrack stations at Brown Naval Air Station at Chula Vista, California, southeast of San Diego, and that station had been modified to receive the signal from one of the transmitters in the Deal satellite.

The time of expected signal acquisition came amid growing anticipation but passed with the devastating absence of any signal. We waited with increasing apprehension, fearing that the rocket or instrument might have failed.

Finally, at about 42 minutes past midnight, about 12 minutes after it was expected, and just as my worst fears were peaking, a voice from the trailer shouted, “Gold [code name for the Earthquake Valley station] has it!”7 There quickly followed reports that other West Coast stations were receiving the signal.

There was a brief silence as the reality set in, and then an outburst of shouts as our pent-up emotions exploded. A few minutes later, at about 12:46 AM, the signal was picked up in the Cape Canaveral trailer where I was standing. The new Earth satellite had completed its first full orbit.

Those in the Pentagon experienced a similar roller coaster of emotions. Von Braun’s later account indicated that the satellite was due on the West Coast at about 12:30 AM EST. But that time came and there was no signal. Eight minutes dragged on, and there was still no signal. As he related:

We were miserable. Obviously, we’d been mistaken. The Explorer had never really gone into orbit. Then, all at once, within 30 seconds, all four California stations reported hearing the Explorer’s signals! America’s moon was definitely in orbit. There’d been just a slight error in our quick estimate of the satellite’s initial speed and period of revolution.8

It became obvious that the rocket had provided a larger than expected thrust, resulting in a higher than planned orbit and a longer orbital period. The orbit had been expected to have a perigee (lowest height above the Earth) of about 220 miles and an apogee (greatest height) of about 1000 miles. The perigee and apogee heights were actually 221 miles and, most significantly, 1583 miles, with an orbital period of 114.7 minutes rather than the 105 minutes that had been originally anticipated.

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Van Allen provided his own typically succinct account of the emotional wait at the Pentagon:

The burning of all four stages was monitored by downrange stations and judged to be nominal. The final burnout velocity of the fourth stage was somewhat higher than intended, and there was a significant uncertainty in the final direction of motion. Hence, the achievement of an orbit could not be established with confidence from the available data. The telemetry transmitter was operating properly, and the counting rate data from our radiation instrument corresponded to expectations…. The reception of the telemetry signal after the lapse of one orbit was necessary before success could be confirmed. The nominal period of the orbit was ninety-five minutes, and the first pass from west to east over northern Mexico was expected to provide the first clear opportunity for reception of the signal by stations in southern California.9

By previous arrangement, I was a member of a group in the War Room of the Pentagon, which served as a center of communications. Others present included Wernher von Braun, Secretary of the Army Wilber M. Brucker, [Department of the Army Chief of Staff] General Lyman L. Lemnitzer, [ABMA’s director] General John B. Medaris, and [JPL’s director] William H. Pickering. For about an hour following receipt of the downrange station reports, there was an exasperating absence of information. Then there began a trickle of affirmative, amateur reports from around the world, none of which withstood critical scrutiny. The clock ticked away, and we all drank coffee to allay our collective anxiety. After some ninety minutes, all conversation ceased, and an air of dazed disappointment settled over the room. Then, nearly two hours after launch, a telephone report of confirmed reception of the radio signal by two professional stations in Earthquake Valley, California, was received. The roomful of people exploded with exaltation, and everyone was pounding each other on the back with mutual congratulations.10

At the Cape, I lingered at the Microlock trailer to listen to further reports of signal acquisition. The crowd there began to thin, and I started looking for my JPL associates. But they had all disappeared! The upper-level JPL and ABMA staffs had all rushed to a press conference at PAFB. As I had not been invited, and had no vehicle, there was nothing for me to do but to hitch a ride back to my motel room and retire for the night.

In that moment of great triumph, I felt terribly isolated. I lay awake for a while, thinking of the momentous turn of events that had occurred during the nearly four months since the Sputnik 1 launch.

In spite of the late hour, a number of memorable press conferences and celebrations took place during that night. This was the news the public was seeking—the Soviets no longer reigned supreme in space. There was a great eagerness to pass out the word and to celebrate this “coming of age.” The reporters rushed from the Cocoa Beach press conference to write their stories for the morning papers.

It was also time for the Washington press corps to be briefed. The U. S. National Committee for the International Geophysical Year (IGY) had insisted that the event be viewed not simply as an achievement of rocket technology, but as an achievement

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for science and as a step in meeting the U. S. scientific commitments for the IGY. Van Allen continued with his account of events immediately following the launch:

Pickering, von Braun, and I were whisked by an army car from the Pentagon to the National Academy of Sciences and smuggled through a back door, where we made our preliminary report to Porter and the IGY staff. We were next led into the Great Hall of the Academy (by then about 1:30 AM) to report to the press. To my astonishment, the room was nearly filled with reporters, photographers, and many other interested persons who had been waiting there since about 10:00 PM. The ensuing press conference was a spirited one. The successful launch of Explorer I was an event of major national and international interest, coming as it did after three humiliating launch failures of Vanguard.11

The photo in Figure 9.3 and others like it were seen in newspapers and magazines all over the world. Although those three pioneers were previously well known in scientific and governmental research circles, the Explorer coverage brought them to the full attention of the much broader public.

At Augusta, Georgia, another drama unfolded. On that Friday evening, President Dwight D. Eisenhower was at the Augusta National Golf Club in Augusta, Georgia, for a weekend of golf and bridge. He had arrived during Friday afternoon and was told upon arrival that the weather conditions for the Jupiter C launching at Cape Canaveral would probably not be good until the following week. After completing

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15 holes of golf and settling down for a few rubbers of bridge with friends, his press secretary, James C. Hagerty, received the first of a series of phone calls from Brigadier General Andrew J. Goodpaster in Washington. Goodpaster was the White House staff secretary and Eisenhower’s liaison man with the Pentagon. In his first call, Goodpaster reported that the weather at the Cape was clearing. At 8:30, Goodpaster informed Hagerty that the weather looked even better and that the rocket was being fueled. In another call at 9:30, Hagerty and the president learned that the launch was proceeding and almost certainly would not be held up by the weather. As the launch time approached, Goodpaster was on the phone again, repeating to Hagerty the launch countdown from Cape Canaveral. At 10:48, as the firing command was given and the rocket was on its way into space, the president got on the phone and, for the next several minutes, listened to Goodpaster relay a word picture of the rocket’s flight.12

After waiting until nearly 1:00 AM, the delighted president put out the first official announcement that the U. S. satellite was in orbit around the Earth. At a dramatic news conference, Hagerty issued the president’s official statement:

Dr. J. Wallace Joyce, head of the International Geophysical office [а/с] of the National Science Foundation, has just informed me that the United States has successfully placed a scientific earth satellite in orbit around the Earth.

The Satellite was orbited by a modified Jupiter C rocket.

This launching is part of our country’s participation in the International Geophysical Year.

All information received from this satellite promptly will be made available to the scientific community of the world.13

At Huntsville, Alabama, a wild celebration broke out somewhat prematurely. Crowds began assembling in the main town square soon after they learned that the Jupiter C had lifted off. About an hour later, but still over an hour before President Eisenhower’s announcement from Augusta, the sirens from Huntsville police cars and fire engines began to scream. That signal had been prearranged by Mayor R. B. Search and other city officials. The Huntsville Times had announced in its afternoon edition that sirens would signal the event, and it was triggered by running telephone conversations between city officials and their esteemed fellow citizens at the Cape. Before the celebration was over, the crowd’s size grew to an estimated 10,000 (out of a Huntsville population of about 56,000). Firecrackers boomed, skyrockets rose from street corners, and the police drove along the main street with their sirens blaring. That local demonstration was likened in the press to those that crossed the nation at the conclusion of World War II.14

The next morning, my Dad captured some of the excitement when he interviewed Van Allen live by telephone for his daily radio program in Iowa City. During that interview, Van Allen commented on the scene in Washington:

CHAPTER 9 • THE BIRTH OF EXPLORER I

Well, I was here at the Pentagon, in Washington during the launching at the so-called central control room where all the information on various aspects of the firing is sent in by teletype and telephone. We were in a small room that was knee deep with generals and other important people, including the Secretary of the Army Mr. Brucker. We followed the whole progress of the operation minute by minute as it occurred, beginning about nine o’clock and continuing, of course, until well after one o’clock here.

… The first report in which we felt certain that the satellite had actually worked was received at about 12:42 EST when it first appeared on the West Coast. The West Coast report showed that both transmitters were working properly, that good cosmic ray data were coming in, and that all apparatus was working normally.15

One of the JPL public affairs officers had promised to pick me up the next morning so I could help with packing the equipment at the Cape. Apparently, he forgot. Without transportation of my own, I was stuck at my motel most of the day. My profound feeling of isolation was eased somewhat that evening, when JPL hosted a huge celebration at the nearby Bahama Beach Club. I attended the beginning of the party but had to leave early for Orlando, so that I could catch the 6:00 AM Sunday morning flight to Iowa City.

The ground tracking and data acquisition stations did not possess equipment to convert the electrical signals into human-readable form. The first opportunity for examination of the data quality and content occurred at JPL for the Explorer I data and for the Explorer III low-power data. The Explorer III high-power data were first examined at NRL. Those activities, as explained earlier, were limited to extracting engineering data and making a cursory check on the operation of the scientific instruments. All further processing and scientific analysis for the cosmic ray data were done at the University of Iowa.

The continuously transmitted data The data arriving at our Iowa City laboratory were processed and displayed as paper strip-charts, from which our data clerks could calculate the GM counter rates. Although those arrangements were archaic when ex­amined after the passage of 50 years, they were standard practice then. The equipment and the procedures were a direct outgrowth of our experience with the balloon, rocket, and rockoon data during the early 1950s.

The ground processing equipment for the continuously transmitted data from Explorers I and III began with an Ampex tape recorder that read the data from the tapes received from JPL. Its output fed a bank of filters and discriminators that provided outputs that mimicked the signals that had been generated by the sensors on the satellite. Those outputs were converted to inked traces on the continuously moving paper charts.

Figure 11.4 shows the equipment setup as it existed in late 1958. The seven-track Ampex tape playback unit in the second rack from the left had been added by that time. The camera recorder extending from the panel on the far right was installed to handle the data from the onboard recorder in Deal II. The full equipment lineup

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shown here was also used during that summer to process the Explorer IV data, as detailed in Chapter 14.

An example of one of the charts made to show the Explorer I high-power data is shown in Figure 11.5. Channel 4, carrying our cosmic ray data, displayed a complete cycle (positive, to negative, and back to positive) for every 32 particles that had been detected by the GM counter.

This figure also shows the cylindrical shell and transmitter temperature data from channels 1 and 2, respectively, and the micrometeorite microphone data on channel 3. The engineers at JPL read a similar chart to determine that the shell temperature (in this sample) changed from 22.5 to 21.0 degrees centigrade, while the transmitter temperature remained steady at 34.5 degrees. Also from the comparable JPL chart, the AFCRC scientists determined that the microphone did not register more than three hits during that pass, since no transition occurred in the output of the factor-of-four scaler that followed the microphone.

Similar charts were produced for the data from the low-power transmitters on both Explorers I and III. On those charts, channels 1,2, and 3 displayed the front cone skirt temperature, front cone tip temperature, and number of severed micrometeorite grids,

FIGURE 11.5 A portion of a SUI paper strip-chart displaying data from the high-power transmitter in Explorer I. These data were recorded on 4 February 1958 at the Microlock station at Patrick Air Force Base, Florida. The time trace at the bottom of the chart indicates that this segment started 14 seconds before 0241 LIT and covered a total period of 111 seconds. The two vertical lines represent the approximate beginning and end of usable cosmic ray data from that pass. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Fibraries.)

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respectively. The low-power system cosmic ray data and time markers were identical in form to those shown in Figure 11.5 for the high-power systems.

Since we used the temperature measurements read by JPL, and had no responsibility for the micrometeorite data, our focus was fully on the channel 4 cosmic ray data and time markers. As a rule, we processed the data from only one of the transmitters for each station pass. In the few cases where both signals were recorded (primarily at the JPL and PAFB stations), we used the better of the two.

The Explorer III onboard recorded data Handling the data from the recorder in the Explorer III satellite instrument package presented a completely different challenge. For a typical operational sequence, the ground station operators prepared for a pass by pretuning their receivers, pointing the antennas in the direction where the satellite was expected to appear, and starting the ground recorder for the low-power signal ahead of time. Arrival of the satellite on the horizon was announced by the appearance of an initially noisy signal from the low-power transmitter. Of course, there was no signal from the high-power transmitter, as it had yet to be turned on.

As the satellite rose above the horizon, the signal from the low-power transmitter became stronger and clearer. The antennas for both the low – and high-power signals tracked the satellite as it progressed across the sky. When the antennas reached a reasonable height above the horizon, and as the low-power signal became sufficiently clear, the operator started the ground recorder for the high-power signal and then transmitted a command to the satellite to turn on the high-power transmitter. If all had been set up properly, the command resulted in the immediate appearance of a signal from the high-power transmitter. After two seconds, the onboard tape recorder began its playback. For occasions when the onboard recorder had stored a full orbit’s data since its last interrogation, its readout took about six seconds. When the tape readout was complete, the transmitter turned off, and the onboard system reset itself to record the next orbit. Thus, the entire readout operation occurred typically within a brief eight-second interval.

The ground station tapes were annotated during recording with voice announce­ments and timing markers, and handwritten comments were entered by the operators in the logs.

The pulses during the brief burst of data appeared at a rate of about 1000 per second. The task in the Cosmic Ray Laboratory’s processing facility was to pick out the burst of information for each pass and to display that information in usable form. Two techniques were employed.

The first, valuable for a quick look at the general form of the data, was to record the signal on another moving pen strip-chart recorder, similar to that being used for the low-power data. Since the pulse rate was somewhat beyond the frequency response of the chart recorder, the traces were distorted, and it was not possible to count the

individual pulses from that source. The charts did convey, however, a very distinctive pattern to trained data readers. As it turned out, once the data blanking due to the high-intensity radiation was understood, those quick-look charts were invaluable in delineating the extent and location of the radiation belt, as described in detail in the next chapter.

The second method for reading the Explorer III onboard tape recorder data used a special camera that had been constructed for the purpose. That camera is shown on the far-right rack of equipment in Figure 11.4. It displayed the received signal on a small cathode ray tube, which had a frequency response far beyond that needed to follow the data traces. Seventy millimeter film moved vertically past the horizontal trace on the cathode ray tube. Thus, the pulses were arrayed along the length of the film, as illustrated in Figure 11.6.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

CHAPTER 16 • SOME PERSONAL REFLECTIONS 439

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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