Category Dreams, Technology, and Scientific Discovery

Inventing the rockoon

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

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

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

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA

Inventing the rockoon

FIGURE 1.1 James Van Allen (left) and Leslie Meredith preparing one of Les’ instrument gon­dolas for launching on 26 January 1952. The gondola frame resting on the ground contained the three-counter telescope at its top, the airborne portion of the telemetering system in the center, and the batteries in the bottom. (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

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

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Подпись: 12Shipboard launching made the concept especially attractive and feasible for several reasons: (1) a ship can steam downwind to minimize the relative wind seen by the tethered balloon-rocket combination while the balloon is being inflated, (2) ships at sea can avoid populated areas and the possibility of damage by returning rockets that are fired in variable and largely uncontrollable directions, and (3) a wide range in geographic position can be covered from a single field installation.

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

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

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

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

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

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA 13

Inventing the rockoon

FIGURE 1.2 The Deacon rocket, modified for use as a rockoon, in front of the Old Capital Build­ing on the University of Iowa campus. From the left, Melvin Gottlieb, Les Meredith (kneeling), Lee Blodgett, Robert Ellis (partly obscured), and James Van Allen. (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

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

Подпись: OPENING SPACE RESEARCH FIGURE 1.3 The two instrument packages for the 1952 rockoon flights. Both were 6.5 inches in diameter. Markings for Les Meredith's instrument in (a) are 1: Victoreen type 1B85 Geiger-Muller counter; 2: Cathode follower circuit board; 3: Five-stage binary scaling circuit; 4: Subcarrier audio oscillator that modulated the transmitter; 5-9: Batteries; 10: Transmitter. Bob Ellis' instrument, in (b), consisted of the spherical ion chamber at the top, followed by the box containing the immediately associated electronics circuits behind the pressure gauge. The next three decks contained batteries, while the lower deck contained a transmitter similar to that used by Meredith. (Courtesy of Leslie H. Meredith and the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

Special Publications 14

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

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

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

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

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

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

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

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

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

Подпись: OPENING SPACE RESEARCH FIGURE 1.4 Preparing one of Les Meredith's rockoon instruments for flight in the temporary laboratory on the icebreaker USCGC Eastwind, fall 1952. From the left, Les Meredith, James Van Allen, and Lee Blodgett (behind Van Allen). (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

16

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

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

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

CHAPTER 1 • SETTING THE STAGE AT THE UNIVERSITY OF IOWA 17

Inventing the rockoon

FIGURE 1.5 Launching a rockoon from the deck of the USCGC Eastwind on the 1952 expe­dition. The balloon had been filled, the rocket had been assembled, and preparations were being made to attach the load line to the rocket. From the left, Lieutenant Malcolm S. Jones, Les Meredith, and James Van Allen. (Courtesy of the Department of Physics and Astronomy Van Allen Collection,

The University of Iowa, Iowa City, Iowa.)

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

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

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

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

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

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

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

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

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

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

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Projects sometimes failed

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

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

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

CHAPTER 4 • THE IGY PROGRAM AT IOWA 95

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

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

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

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

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

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

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

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

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

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Подпись: 96made a series of three flight attempts from the Wallops Island test facility on 21 and 23 May and on 27 June 1959. Unfortunately, none of those flights reached an altitude high enough to meet the primary scientific objectives.1011

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

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

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

Continuing reactions

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

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

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

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

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

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Подпись: 174early as they possibly could, and that it just happened to occur at that opportune moment.

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

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

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

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

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

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

Washington Daily News were headed:

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

U. S. Caught Flat Footed

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

How to Tune In

How to Look for It

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

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

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

CHAPTER 6 • SPUTNIK! 175

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

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

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

Environmental testing

An elaborate series of environmental tests were performed on all payload compo­nents, subassemblies, and the fully assembled payloads. The environmental testing philosophy included two types of test: (1) type approval testing of an engineering model payload and (2) flight acceptance testing of all flight models.

The primary purpose of the type approval tests was to assure that the basic designs were adequate to withstand the rigors of launch and the in-orbit environment. Those

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 239

test levels were substantially higher than actually expected, to provide a margin of safety.

Flight acceptance testing was designed primarily to weed out errors in construction and early parts failures. Care was taken not to exceed the expected launch levels to avoid fatiguing any of the flight components.

Without going into the many details of test configurations and levels, the battery of environmental tests included (1) shock, (2) acceleration, (3) spin, (4) temperature (static, cycling, and long-duration), (5) combined temperature and vacuum, and (6) vibration.

A failure of the Engineering Model cosmic ray package during its type approval testing on 7 January caused considerable alarm. During the second vibration test, the GM counter rate was seen to be somewhat low. Upon closer examination, it was found that the ceramic insulator supporting the central wire in the counter had cracked within its encapsulation—a recurrence of another of the problems encountered earlier during testing of the Vanguard prototype instrument.

It was too late to change the design without delaying the Explorer I launch. Since the flight payloads had satisfactorily passed the lower-level flight acceptance tests, it was decided, with great trepidation, to proceed without modifying them. Luckily, the final flight instrument survived its launch, and the instrument operated perfectly in orbit.

The entire suite of tests ended with a measurement of the overall temperature characteristics of each completely assembled flight payload. They were placed in a temperature chamber and operated solely from their internal batteries. The GM coun­ters were illuminated by a standard Co60 radioactive source. The resulting counting rates became the standard for operational checks made on the payloads at the launch site.

At the end of all Deal I flight payload testing, I calculated that the overall variation of GM counting rate with temperature would be in the neighborhood of 5 percent over the temperature range 0 degrees to 50 degrees centigrade. Although it would have been better to relocate an internal temperature sensor closer to the GM counter to facilitate more accurate correction of that temperature effect, it was too late to do so for Deal I. However, that was done for Deal II.30

All in-flight payload temperature data were tabulated at JPL and were used in correcting the GM counter flight data at Iowa.31

The Deal I satellite bore no resemblance to the Vanguard configuration. It was, however, similar to the configuration that we had worked out at Huntsville during the preceding summer, as can be seen by comparing Figures 7.1 and 8.4.

The first Deal I flight payload was completely assembled, tested, and weighed by 11 January. Its total weight, not including the Rokide thermal control coating on the shell and the fourth-stage rocket motor, was 18.51 pounds (some records list

Подпись: 240

Environmental testing Подпись: ONE FOOT

Environmental testingOPENING SPACE RESEARCH

MICROMETEORITE GRIDS

FIGURE 8.4 The Explorer I satellite, including the final rocket stage below the central high – power antenna gap. The shell ofthetop instrument package is cut awayto showthe arrangement ofthe inside components.

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

Environmental testing

FIGURE 8.5 The Explorer I satellite spare instrument. The cylindrical shell and nose cone have been removed to show its construction. The vertical white stripes on the shell and cone controlled the temperature of the internal electronics. The identification of components was as shown in Figure 8.4. (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The Uni­versity of Iowa, Iowa City, Iowa.)

18.13 pounds). By that time, the booster rocket and upper stages had been completed at ABMA and JPL and transported to the Cape. On 17 January, the Redstone booster was hoisted to a vertical position on Launch Pad 26A. Installation of the upper-stage rocket clusters followed, as the Jupiter C took shape.

In addition to an engineering development model, three flight payloads were assem­bled for the Deal I launch. Figure 8.5 shows one of them. The payload designations, the GM counters used on each, and their ultimate dispositions, as far as they are known, are tabulated in Table 8.1. The GM counter numbers are listed because they are the only identification durably impressed within the entire instrument packages, and therefore the only numbers that can be used to positively identify surviving pay­loads. The numbers are very faintly stamped on the GM counter stainless steel shells just above their threaded mounting flanges.

The space museum at JPL possesses a full-scale model of Explorer I, plus a cutaway version of the instrument. The cutaway instrument includes a cosmic ray counter and its electronics. As it is believed that only four of the complete Deal I packages were built, it is possible that this unit is the engineering model.

Additional models have been displayed from time to time. Those models are likely either prototype units prepared within JPL before the official decision to proceed with the Deal program, and therefore lacking the scientific instruments, or else spare parts

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TABLE 8.1 Disposition of the Deal I Instruments

Deal I GM

Designation

Counter Number

Ultimate Location

Engineering model

Probably 63

Probably the one located in the JPL museum in Pasadena

Flight payload I

59

Launched on Missile 29 as Explorer I on 31 January 1958

Flight payload II

55

Sent to SUI in April 1958 for calibration; returned to JPL per their 16 December 1958 request; presented to the Smith­sonian National Air and Space Museum, Washington, D. C.

Flight spare

57

Cannibalized for Explorer IV development

Подпись: 242that appear authentic only when viewed from the outside, namely, antenna insulators,

shells, and cones.

Data flow

Figure 11.3 illustrates, in a greatly simplified form, the path by which the low-power data from Explorers I and III and the high-power data from Explorer I passed from the sensors in space to produce human-readable tables and graphs in our Iowa laboratory. The Explorer III high-power data were handled quite differently, as described later.

Pulse rates registered by the GM counter and the micrometeorite impact micro­phone were scaled on the satellite, that is, reduced by factors of 32 and 4, respectively, to produce more manageable rates for telemetry. The sensor signals modulated the frequencies of audio oscillators, and the tones were combined to form composite signals, which, in turn, modulated the satellite transmitters.

At the ground receiving stations, the receiver outputs were recorded on magnetic tapes, and the tapes were shipped to JPL. There the data were examined to ascertain their quality, and the satellite temperatures were computed. Initially, magnetic-tape copies of appropriate data channels were sent to SUI and the Air Force Cambridge Research Center (AFCRC). Somewhat later, the original tapes were sent to Iowa.

In our laboratory, the tapes were played back and the signals were passed through a bank of filters that separated the four original audio tones. The filters were followed by discriminators that converted the audio tones to the relatively slowly varying signals like those that had originated in the satellite. Thus, the outputs of the four

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Подпись: 298discriminators were identical with the inputs to the satellite multiplexer (except for the addition of noise). Those four signals drove moving-pen galvanometers to produce ink traces on continuously moving paper strip-charts.

Argus and Explorers IV and V

T

here was no time for relaxation following the Explorer III launch. Even before the public announcement of the discovery of the high-intensity radiation on 1 May 1958, immense pressure was building in the United States for follow-on missions to address the questions posed by the data from the first two successful Explorers.

The Army group at Huntsville was already working on a next logical step—the substitution of the Jupiter missile for the Redstone as the first stage. The larger booster would be topped by the same cluster of solid fuel upper stages as employed in the Jupiter C-Juno I configuration. They dubbed the enhanced vehicle Juno II, and work quickly began at Huntsville on designing a satellite for that launcher. That satellite was referred to as the IGY Heavy Payload initially, and, after NASA was formed in October 1958, it was given the prelaunch designation Payload 16 (PL-16). When its second launch attempt was successful in October 1959, it became Explorer 7.

However, work on that satellite was interrupted by another new project, Argos and Explorers IV and V

Some Personal Reflections

M

y studies in physics and engineering at the Iowa university, the work in the Physics Department’s Cosmic Ray Laboratory, and our family life were inextri­cably intertwined and all-consuming throughout the seven and a half years that I was there. That was the most exciting period of my life and had more to do with shaping my professional future and person than anything else that happened during my entire life.

Family life

When I entered the university in early 1953, Rosalie and I began our new experience with daughter Barbara, who was approaching her first birthday. Sharon was born in June 1953, at the end of my first semester of study. Son George came along just eight days before the Explorer III launch, and daughter Kathy arrived just as I was receiving my Ph. D. diploma.

For the initial months, we managed the Ludwigheim family farm near Tiffin while Dad and Mom were in Des Moines for his participation in that year’s session of the state legislature. I commuted the eight miles to the campus. When my parents returned in the early summer, Rosalie and I moved our growing family into Finkbine Park.

That home for four years contained a very small living room, a miniscule kitchen with a small table for dining and homework, a bathroom with a minimal shower stall, two small bedrooms with diminutive closets, a rather large storage closet for all the things we could not cram into the living spaces, and a single oil-fired space heater in the living room.

In spite of the rather austere living conditions, life there was, overall, enjoyable. Our neighbors were also struggling students, most with children who were about the

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Подпись:same age as ours. We sometimes referred to our little enclave as “rabbit village.” Our common financial and living conditions, plus our shared common purpose, resulted in a strong bonding and sense of community. We count some of our neighbors there among our closest friends yet today, even though their interests and training were in completely different fields and they took up postgraduation work in all parts of the country.

Our initial rent of $35 per month included electricity, oil for the space heater, and gas for the kitchen range and water heater. By the time I ended my undergraduate work in 1956, the monthly rent had ballooned to $50.

One year into my graduate work, in the summer of 1957, I signed up for only a three hour research load to allow more time for my satellite design work. The light summer academic load meant that I was no longer qualified for married student housing, so we rented a small two-bedroom house on Rochester Avenue near Iowa City’s eastern edge. It had a small combined living and dining room into which our 9 by 12 foot rug exactly fit. Fortunately, the house had an unfinished full basement. Although initially unsuitable for other than our washer and dryer, it had great potential. Its walls and ceiling were still covered with a thick layer of grime from the days when the coal bin was in active use. I hosed off the worst of it, rented a paint sprayer, and encapsulated the walls and ceiling with a thick coating of paint. I also rewired the basement to make it safer. A study area was delineated by a bed sheet hanging from one of the open joists. With a desk fashioned from a hollow-core door and set of wrought-iron legs, I had a comfortable place for study somewhat removed from the noise and confusion of the family and our tight living quarters upstairs. Our initial monthly rent there was $65, seemingly a princely sum at the time.

Rosalie worked just as hard as I did during our university years. Obviously, she carried the major responsibility for our household. In addition, she worked as a nurse’s aide at the University Hospital for a two year period. While she worked the night shift during the first of those years, she would come home after work to prepare breakfast, take care of the children during the morning, and feed them lunch. Then, when she put them down for their naps, she would get a short rest. After the children woke, she took them to our neighbor Charlotte Boley, who watched them until suppertime approached. Then Rosalie would collect the children and prepare supper. During most of that year, she felt that she was floating in a daze.

That regimen was too hard for her to sustain, so she moved to a shorter 7:00-11:00 PM evening shift during her second year there. During that era, she prepared the children for bed before leaving for work, and I watched them and put them to bed while I studied until her return.

Near the end of our university epoch, Rosalie worked for about two years at the First Presbyterian Church, where we were members. On five evenings each week,

CHAPTER 16 • SOME PERSONAL REFLECTIONS 431

she oversaw the youth lounge, where students gathered from the nearby campus. On Sundays, she fixed evening meals for them.

We had one extended break from the campus routine during my student years, when we spent the summer of 1954 with Rosalie’s parents in Corvallis, Oregon. Her father managed radio station KRUL at that time, and he offered me a position as chief engineer for the summer. The FCC First Class Radio Telephone Operator’s License that I had earned just before leaving the Air Force qualified me for the position. When we arrived in Corvallis, I discovered to my surprise that the position also entailed working a shift as radio announcer—an interesting situation. My voice was well suited to radio, but I knew that, being a relatively nonverbal introvert, I lacked the proclivity for extended extemporaneous chatter needed by a radio personality. That had been borne out by my experience with amateur radio, where I enjoyed building the equipment but disliked rambling on the air about nothing in particular. At the radio station, I dreaded the on-air unscripted tasks such as conducting chat shows.

As mentioned earlier, we did take shorter family vacations from time to time. With everyone in the family enthusiastically embracing tent camping, most of those vacations involved trips by car to various locations, with camping along the way and in the parks that we visited. Those gave us complete breaks from our normal daily lives at a cost that we could afford.

Rosalie and I carefully protected certain family activities. With few exceptions, break­fast and the evening meal (supper in midwestern rural parlance) were carefully guarded family affairs at the dining table. A review of my notebooks and journals confirms that Sundays were nearly always preserved for church and family. That included many Sunday afternoons with my parents and other family members at Ludwigheim. On other Sundays, we went on drives, visited a nearby park for a picnic, or engaged in some other family activity.

In retrospect, my family did not receive as much of my day-to-day attention as might have benefited all of us. Overall, however, the children received good guidance and loving care and developed a strong sense of responsible behavior. Interestingly, none of them followed my lead into the physical sciences. Rosalie, who eventually realized her lifetime goal to become a registered nurse, appears to have had a greater influence in setting their life’s directions. Two of our children became nurses, one a medical doctor, and one a Ph. D. animal virologist.

The Early Years

B

y the fall of 1952, all of the essential elements were in place at the Iowa Physics Department for a sustained program of upper atmospheric research. There was outstanding leadership, a capable staff, a cadre of eager students, appropriate tools and techniques, experience with field operations, and modest funding. Early scientific re­sults were appearing in print. James Van Allen and his new group were already solidly established in the national and international science arena as leading contributors to cosmic ray research.

Entering opportunity’s door

Purely by chance, I arrived on the scene at about that time. When my tour of active duty with the Air Force ended on 18 December 1952, I returned to my Iowa family home near the tiny town of Tiffin, located just eight miles west of Iowa City. My single-minded goal was to enter the University of Iowa to study physics. With no understanding of the significance of the situation that was developing at the time, a tremendous opportunity was opening.

For a number of years my father, George M. (GM) Ludwig, conducted a daily morning program over local radio station KXIC from his Ludwigheim farm home. He had interviewed Van Allen, Meredith, and Blodgett in October upon their return from the summer’s rockoon expedition. Van Allen and Meredith returned for a follow-up interview a few days after I arrived home. In the course of that morning’s discussions, Dad (acting as my self-appointed agent) turned to Van Allen and asked, “George is just back from the Air Force and is looking for a job. Might you have something for him?” Van Allen replied that he might and suggested that I come to his office the following Monday to pursue the question further. I did so, and he offered me part-time

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Подпись: 22work as a research aide in his Cosmic Ray Laboratory, at 75 cents per hour. I eagerly accepted his offer, began work immediately, and was well established there when the spring semester opened in February 1953.

Large balloons

Anderson’s 1957 Fort Churchill expedition As Kinsey Anderson was arriving in Iowa City in September 1955, our summer rockoon expedition was returning with new information about the auroral soft radiation. When Kinsey saw those results, he noted that the anomalous radiation was occasionally penetrating to altitudes lower than the rockets’ peak altitudes. In fact, the auroral soft radiation was sometimes seen at altitudes that might be reachable directly by Skyhook balloons. He believed that balloon flights, flown for extended periods of 10 to 30 hours at their peak altitudes, might be able to capture synoptic and time variation information on both the auroral soft radiation and low-energy cosmic rays that was not obtainable from the relatively short duration rockoon flights.

Kinsey had been impressed by a seminar at Minnesota in late 1954, in which Phyllis Freier described a potential IGY project for studying cosmic ray variations. She suggested that a series of balloon launches covering an extended period carry a standard set of cosmic ray particle detectors to study those variations.

CHAPTER 4 • THE IGY PROGRAM AT IOWA 97

Those two lines of thought converged, prompting Kinsey to submit a proposal to the U. S. National Committee for the IGY in November 1955. It called for a large number of high-altitude, long-duration balloon flights to be carried out during 1957 at Fort Churchill, Canada, a site well within the auroral oval.14

Kinsey immediately began designing an instrument to achieve that objective. It in­cluded three basic detectors: (1) a GM counter telescope, (2) a single GM counter, and (3) a scintillation detector using a thallium-activated sodium iodide crystal mounted on the front of a photomultiplier tube. The scintillation detector was configured to have high efficiency for X-ray radiation at energies above about 10 keV He expected the combination of instruments to reveal new information about the energy spectrum of the parent electrons that were responsible for the auroras.

However, Kinsey ran into serious problems in moving his project forward. To begin with, rules at the University of Iowa at that time did not permit junior researchers to submit proposals to outside agencies. Van Allen stepped in to sidestep that hurdle. The next step was to gain U. S. and IGY programmatic and financial support. In late 1955, Homer Newell’s Special Committee for the IGY (operating under the umbrella of the U. S. Upper Atmosphere Rocket Research Panel) reviewed his proposal and rejected it, apparently through some misunderstanding between Kinsey and the committee. Newell went so far as to declare that, beyond the funding issue, the U. S. military support group at Fort Churchill would not be permitted to support it.

Kinsey then attempted to obtain funding via the National Academy’s Technical Panel on Rocketry for the IGY. Scott E. Forbush, as its chairman, explained that nearly all of their funds for U. S. IGY cosmic ray research had already been committed. He asked if $15,000 would permit a useful program (compared with the $60,000 that Kinsey had requested). The panel also stated that, if approved, Kinsey would have to switch to a substantially different detector complement, to bring it more in line with programs at other locations that had already been approved. Specifically, it would have to include two instruments like those being used by the Minnesota group: a 10 inch diameter Neher-type integrating ionization chamber and their single GM counter design. Under those conditions, it would not be possible for Kinsey to in­clude the envisioned scintillation detector, and the nature of the project would be substantially different than originally envisioned.

Nevertheless, Kinsey quickly replied that he would be able to achieve meaningful results with that arrangement and submitted a revised proposal for the new instruments and a reduced number of flights. That resulted in approval for the modified program in April 1956.

Even then, the way was not clear. Newell had forbidden support by the U. S. military support at Fort Churchill, so other arrangements had to be made for launch­ing the balloons. Acting on Van Allen’s suggestion that he contact Donald C. Rose

Подпись: 98

Подпись: FIGURE 4.3 Kinsey Anderson evacuating and filling three of the ion chambers being prepared for his late summer 1957 Fort Churchill, Canada, expedition. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Libraries.)

OPENING SPACE RESEARCH

of the Canadian National Research Council, the problem was eventually resolved when Kinsey’s program was made part of the joint Canadian-U. S. IGY program, with Canada taking responsibility for the launches. Kinsey later reported that the arrangement with the Canadians turned out to be a very happy and productive one.

Developing the new instruments presented another major challenge to Kinsey, as he had no previous experience with ion chambers. With help from several students, and benefiting from the instrument shop’s much-earlier experience with Bob Ellis’ ion chambers (described in the first chapter), he prepared the instruments during 1956 and the first half of 1957. The spherical chambers had to be designed, manufac­tured, and assembled, and then they had to be baked out, evacuated, filled with argon gas, and calibrated (Figure 4.3). And the GM counters and various associated elec­tronics had to be designed and built. Completing the work was touch-and-go, and the last few ion chambers were completed only days before the first scheduled balloon launch.

With the various delays, final approval for the flights was not obtained until April 1957, only 10 weeks before the field operation was to begin. The schedule was met, however, and between 7 August and 7 September 1957, Kinsey, with help from three undergraduate students, directed the launch of 14 of his balloons from Fort Churchill. In total, they obtained about 175 hours of data from altitudes above 18 miles.

Kinsey related a fascinating tale about a highly improbable event that occurred during their field operation. In his words:

CHAPTER 4 • THE IGY PROGRAM AT IOWA

The program of IGY balloon launches in 1957 was punctuated by a remarkable coincidence in space, time, and people. After we had launched a balloon on 7 August, we hurriedly loaded the inflation gear into the panel truck and sped toward the main base and our telemetry station. The road closely paralleled the western shore of Hudson Bay. Glancing eastward over the Bay I saw a polyethylene research balloon coming out of a low-lying cloud layer. The balloon we had just launched had moved rapidly westward and away from Hudson Bay only a few minutes before. The intruder collapsed onto the rocky beach. We stopped the truck, started the Homelite generator, and snapped on our checkout telemetry receiver. We were indeed still receiving the VHF telemetry signal from our balloon off to the west. I then guessed that the interloper had to be a balloon used by the SUI group launching Rockoons in the Davis Strait half a continent away to the East. Running to the beach where the balloon lay partly in the water and partly on the beach, I chopped off the end portions with the hunting knife I carried (most persons engaged in launching large balloons carried such a knife believing it might save their life should they become fouled in a line as the balloon was released). When we returned to Iowa City, I showed the balloon ends to Laurence Cahill who verified they were from a balloon of the type used that summer for the Rockoon launches.15

Although most of Kinsey’s flights provided interesting and useful data, the one on 29 August 1957 was especially noteworthy. A Forbush decrease in cosmic ray intensity marking the beginning of a geomagnetic storm was detected by monitors at numerous ground locations while the balloon flight was in progress. The cosmic ray decrease at flight altitude was about twice as large as that observed on the ground. Although soft radiation (X-ray) was seen frequently throughout the flight, a strong burst of X-rays lasting about five minutes was seen in the balloon’s instrument at a time coinciding with the beginning of the storm. Ground observers reported that they had seen bright and active visible auroral during the period of observation. That was one of the earliest cases where the direct effect of energetic particles (electrons) was associated with such a geomagnetic phenomenon.

During flights on several other nights when quiet auroral arcs appeared in the sky, no similar X-rays were seen by the balloon instruments. This led to Kinsey’s inference that the quiet arc type of aurora did not involve electrons having energies high enough to produce X-rays that could penetrate that deeply into the atmosphere.16

Returning to Fort Churchill in 1958 Following up on his 1957 success, Kinsey proposed a series of balloon flights for August-September 1958 to further study the auroral zone radiation. Again, the balloons were to be launched from Fort Churchill. Approval was much more straightforward for that proposal—he submitted it to the U. S. National Committee for the IGY in October 1957, and it was approved relatively quickly.

Assisted by Donald Enemark, they made substantial improvements in the instru­ment design. They improved the low-temperature performance of transistor ampli­fying and scaling circuits, and the weight of the package was reduced by replacing the vacuum tube transmitter with one employing silicon transistors. In August, the

OPENING SPACE RESEARCH

Подпись:two, joined by students Donald Stilwell and Louis Hinton, made their way to Fort Churchill with their instruments.

During the August-September 1958 period, they made 10 balloon flights, col­lecting 150 hours of high-altitude data. Kinsey’s account of the launch operations provides interesting reading.17 It tells of launches made during windy conditions from locations ranging from the leeward side of an aircraft hangar to the playground of the Fort Churchill elementary school, where many eager young faces watched from the windows. The flights produced varying results, with some indicating only quiet-time background cosmic radiation, while others showed moderate auroral X-ray activity.

The flight launched at about 8:30 local time the evening of 21 August was more exciting. By 10:30, the balloon had settled at its float altitude. Throughout the night, the counting rates were monotonously constant, revealing only the presence of the normal background cosmic rays. They were sufficiently uninteresting that Kinsey felt comfortable in catching a few hours’ sleep. After breakfast, he returned to the receiving station to find the situation unchanged. However, at about 9:45 on the morning of 22 August, things changed dramatically. The pen movements on the data recorder began to speed up—over several minutes, the rates climbed to previously unseen levels. All detectors were vigorously responding to some form of ionizing radiation. In Kinsey’s words:

I was especially struck by the rapid pulse rate of the usually sluggish ionization chamber.

Ionizing radiation was reaching the balloon at intensities far beyond anything that we had encountered on any previous flight. Recovering my composure, I began to think about what the detector responses were telling us. Careful study of the data received to that point convinced Donald Enemark and me that there were no instrument malfunctions. The ratio of the ion chamber to single counter response was much higher than could be produced by X-rays or gamma rays; therefore, the ionizing radiation could not be due to auroral associated X-rays.

The most powerful information for identifying the ionizing radiation came from the ion chamber-to-counter telescope ratio. That ratio told me the ionizing radiation could not be electrons, alpha particles, or heavier atomic nuclei. The measured ratio was just what I expected from fluxes of protons. After our return to Iowa City, I rechecked calibrations and made more detailed calculations and found the average energy of the protons arriving at our balloon over Fort Churchill, on 22 August 1958 to be 170 MeV.18

A highly varying pattern evolved over the next hours. The counting rates dropped and rose over a three hour period, and then the heavily ionizing radiation began a slow but steady decline. That continued throughout the rest of the morning and afternoon. Some protons were still present, however, when the transmission from the balloon ceased at about 5:00 in the afternoon of 22 August.

The team soon learned that an intense burst of radio noise was emitted from the Sun starting at about 8:15 AM, about 90 minutes before the protons were seen by the

CHAPTER 4 • THE IGY PROGRAM AT IOWA 101

balloon instruments. They also learned that a great solar flare had been observed to begin about 75 minutes before the proton arrival.

That event did not produce a measurable effect in ground neutron monitors, as did some other rather rare superflares, like the one that occurred on 23 February 1956. It was clear that the proton energies were too low for either the primary or the secondary particles to penetrate the atmosphere and reach the ground.

From his flights and the work of others, it soon became understood that the Sun produces, in addition to the huge flares previously seen, more frequent smaller flares that emit large fluxes of protons of much lower energies than those produced by the large ones. This new knowledge played an important role in the evolution of the thinking about solar processes and solar-terrestrial relationships.

McDonald to Missouri and Minnesota On 27 June 1958, with help from aide Louis Hinton, Frank McDonald flew a two million cubic foot Skyhook balloon from Moberly, Missouri, to study latitude variations of the cosmic ray heavy nuclei and their relation to the sunspot cycle. The instruments were recovered the next day, and Frank and Louis flew immediately to International Falls in northern Minnesota to fly them again there. Those observations further extended the latitude range of Frank and Bill Webber’s earlier heavy-nuclei observations.

And Anderson back to Canada Kinsey Anderson’s final Iowa balloon-launching expedition was to Resolute, on Resolute Bay, Cornwallis Island, Canada. He chose that location because of its nearness to the Earth’s north magnetic dip pole (the location of the north magnetic dip pole is considerably removed from both the north geomagnetic pole and the north geographic pole). On that expedition, in July 1959, Kinsey, Don Enemark, and Robert Lamb launched 10 balloons into very high intensities of particles produced by large solar flares.

Balloons as a continuing feature Balloon flights by the Iowa group continued throughout the rest of the decade, both with the huge Skyhook balloons and with much smaller ones.

Balloons are still in use today, primarily to achieve long flight durations at relatively low cost. Flight capabilities have grown dramatically since the 1950s. To illustrate, a new balloon flight duration and distance record was set in early 2005. It involved a flight of nearly 42 days, during which the balloon and its instruments traveled through three orbits around the South Pole. Launched from the National Science Founda­tion’s McMurdo Station in Antarctica on 16 December 2004, it landed on 27 January 2005 after traveling 27,410 miles. The enormous balloon, weighing 4055 pounds, ex­panded to a diameter of more than 450 feet at its ceiling height of 125,000 feet (about 24 miles). The balloon carried a Cosmic Ray Energetics and Mass experiment de­signed to explore the supernova acceleration limit of cosmic rays, the relativistic gas of protons, and electrons and heavy nuclei arriving at Earth from outside the solar

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Подпись: 102system. That flight was an early demonstration of the developmental NASA Ultra­Long Duration Balloon, which is expected to extend flight times up to 100 days.19 Balloon sizes are now up to nearly 30 million cubic feet, capable of carrying payload weights exceeding 5000 pounds.20

Summarizing the Iowa experience with balloons during the decade of the 1950s, many Iowa physics students did at least part of their research with balloon-borne instruments. At first, very small, inexpensive latex balloons were used by graduate students Leslie Meredith, Robert A. Ellis Jr., Ernest C. Ray, Kenneth E. Buttrey, William R. Webber, and Raymond F. Missert. By the end of the decade, after the Skyhooks had entered the scene, many additional researchers had used balloons. They included (in addition to the work of McDonald, Kinsey Anderson, Cahill, and McIlwain described earlier) graduate students Hugh Anderson and Ralph Tuckfield. Many of those flights contributed significant new information about radiation in and above the Earth’s atmosphere.

U. S. Satellite Competition

L

ife within the U. S. space program changed dramatically following the launch of the first Sputnik. The public surprise and outcry following failure of the United States to be first in space energized everyone in a way that no other event short of a war could have done. Their feat vividly demonstrated that the Soviets were capable of launching nuclear weapons over intercontinental distances. The realization that the Soviets really were ahead of us in developing large, long-range missiles resulted in a strong U. S. reaction, and the cold war race for rocket supremacy built to a feverish pitch. The pressure for the United States to get a satellite into space mounted, only adding to the frustrations of the Vanguard personnel, who were having problems in bringing their launch vehicle to a state of readiness.

No account of the early U. S. satellite program would be complete without stepping back in time to examine the fierce competition for developing the U. S. International Geophysical Year (IGY) satellite launcher, the decision to go with the Vanguard proposal, and the persistent effort to keep a losing proposal alive.