Category Dreams, Technology, and Scientific Discovery

Artificial Earth satellites

Serious thinking about reaching farther from the Earth’s surface for scientific research began immediately after the cessation of hostilities at the end of World War II. As

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stated earlier, atmospheric sounding rockets were widely employed throughout the post-1945 era. But the need for much longer-term observations at higher altitudes was widely recognized.

Early U. S. thinking about satellites In May 1945, soon after his surrender to Allied troops in Germany, Wernher von Braun summarized his views on the potential of rocket-launched satellites for his U. S. Army captors.12 Discussions of satellite possi­bilities within the Army stimulated Navy interest, where the primary initial emphasis was on the observation of ship movements at sea. In October of that year, the Navy became the first U. S. agency to take a major formal step to evaluate the prospects. Its Bureau of Aeronautics set up a Committee for Evaluating the Feasibility of Space Rocketry. That group soon recommended that the design of an instrumented Earth satellite be started.

In December 1945, the Guggenheim Aeronautical Laboratory (later renamed the Jet Propulsion Laboratory) at the California Institute of Technology was given a con­tract to investigate the relationship between carrier vehicle performance, the weight of a satellite, and the height of its orbit. The first result of the Guggenheim study was to point out that the system initially envisioned was too expensive to be supported by then-extant Navy budgets. At that point, the Navy tried to enlist help from the other services. A meeting was held on 7 March 1946 between Navy and Army officials, but the U. S. Army Air Corps declined the invitation to participate. What the Air Corps neglected to mention was that they were starting their own investigation, and they had no intention of sharing their efforts with the Navy.

In a November 1945 report, Air Corps general Henry H. (Hap) Arnold expressed his belief that a spaceship “is all but practicable today.” The next month, an air corps scientific advisory group stated that long-range rockets were feasible, and satellites were a “definite possibility.” In early 1946, the Air Corps commissioned a very highly classified independent study, partly to demonstrate that they, in addition to the Army Ordnance group and the Office of Naval Research, possessed competence in this arena and were qualified to assume responsibility for military satellite missions. Project RAND (standing for “Research ANd Development”) was set up by the air corps within the Douglas Aircraft Company at its El Segundo, California, plant to undertake that study.

That group achieved the remarkable feat of producing its first (classified) report, Preliminary Design of an Experimental World Circling Spaceship, by 2 May 1946.13 That 324 page report envisioned a 500 pound satellite to be launched by a booster that would use the technology obtained from V-2 experience. In addition to its technical assessments, the report identified a number of potential military missions for such a spacecraft, including observation, attack assessment, communications, weather recon­naissance, weapons delivery, and the technological development of missile guidance. There was also a strong focus in the report on the gathering of scientific information

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Подпись: 72about the Earth and its near-environment. The report made the following prescient observation:

Though the crystal ball is cloudy, two things seem clear:

(1) A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century.

(2) The achievement of a satellite craft by the United States would inflame the imagination of mankind, and would probably produce repercussions in the world comparable to the explosion of the atomic bomb.

The problem outlined in the report was that the cost was expected to be $150 million, a prohibitive amount for that era. A year later, RAND presented a new plan for a smaller satellite that it claimed could be launched for $82 million. But a technical evaluation by a Department of Defense group under Clark B. Millikan reviewed both the Air Corps and Navy plans and reported that the identification of some specific military uses would be required before a military development project could be justified. The final nail was driven in the coffin of those earliest efforts to develop an actual military Earth satellite on 15 January 1948, with Vice Chief of Staff Hoyt S. Vandenberg’s delaying statement that “satellites should be developed at the proper time.”14

Thus, by the opening of the 1950s, there was a strong agreement within military circles that satellite launches were possible. Although many of the suggested jus­tifications for launching military satellites did not appear to warrant the high cost, there was an additional factor. Throughout the cold war era, there was an urgent need for intelligence information to assist in assessing USSR military capabilities. U. S. aircraft photoreconnaissance overflights were made, but the Soviets strongly objected to them, the aircraft were detectable by radar, and they were vulnerable to antiaircraft fire from the ground. But, although satellites offered the possibil­ity of reconnaissance from above the range of ground fire and aircraft, U. S. policy makers were seriously concerned that the Soviets would object to them as a sim­ple extension of what they viewed as the warlike lower-level aircraft flights. The Soviets might then be expected to develop an antisatellite capability, and Earth orbit would become just another battlefront, rather than an outpost for a broad range of uses, including peaceful scientific exploration of the universe and the application of space technology to Earth resource management, communications, and other practical uses.

Within the nonmilitary arena, concrete thinking about space flight was also evident immediately following the war. In 1946, staff researchers at the Naval Research Laboratory (NRL) discussed the use of Earth satellites for unclassified high-altitude research. The idea was set aside at that time as being premature—they concluded that the state of the technology was simply not yet available.

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The scientist’s hopes for research in space remained only a dream into the early 1950s. The popular press began to help in spreading the word. Although many of the concepts discussed openly did not benefit directly from the military studies because of the latter’s high security classification, an expectant culture of serious space en­thusiasts slowly emerged. The American Rocket Society began pressing the case for the scientific and peaceful conquest of space in the opening years of the 1950s. It established a Space Flight Committee in 1952, with Milton W. Rosen of the NRL as chairman. The following year, that committee, after being provided with at least some of the sensitive military information, issued a classified report with details about the kinds of actions that would be required to promote space flight. They suggested that the “National Science Foundation study the utility of an unmanned satellite vehicle to science, commerce and industry, and national defense.” They went on to state that “examples of these research uses might be: for a superior astronomical observatory site; for biological and chemical research utilizing non-gravity conditions; for elec­tronic research utilizing a more perfect vacuum of unlimited volume for microwave research in free space; cosmic ray studies; and sophisticated nuclear research; etc.”

A year later (1954), the Space Flight Committee followed its earlier report with an unclassified report to the National Science Foundation titled “On the Utility of an Artificial Unmanned Earth Satellite.” It stated that a satellite would be one of the most important steps toward advancing the cause of space flight, and that it would also increase the country’s scientific knowledge.

Since the IGY was undertaken as a completely open, purely scientific international effort, its planning involved a huge body of scientists, many of whom were unaware of most of the classified military activity. Those who did know about it were constrained from discussing it in the unclassified IGY planning arena.

The possibility of using satellites for scientific research became much more openly discussed following an event that occurred in 1952. Fred Singer began presenting and publishing a series of unclassified papers that espoused the use of small artificial Earth satellites for scientific investigations.15>16>17>18>19>20 As summarized later by Singer:

Partly stimulated by lectures I gave to the British Interplanetary Society in London in 1951,1 developed ideas for an instrumented earth satellite to carry on the kinds of measurements we hadbeendoinginrockets…. It was quitearadical ideaat the time, whichoffendedthosewho pooh-poohed any notion about working in space as well as those who had already set their aim on manned exploration of the solar system. What I brought to the discussion, mainly, was the notion that instrumentation could be miniaturized and that useful research could be done with a satellite weighing only a few kilograms—even if it survived only for days or weeks….

So was born the MOUSE—the Minimum Orbiting Unmanned Satellite of the Earth—with the help of futurist Arthur C. Clarke and rocket engineer Val Cleaver and some alcoholic conviviality at the Players’ Club near Trafalgar Square. For the next few years, I would try to think of all kinds of experiments that could be done by such a satellite: meteorological observations, including worldwide measurements of ozone; ultraviolet measurements of the

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Подпись:Sun and other stars; measurements of incoming interplanetary dust as well as the zodiacal light/solar dust corona; magnetic measurements of ionospheric currents; the use of the satellite lifetime to measure the density of the upper atmosphere; primary cosmic rays, and finally, geomagnetically trapped particles. All these ideas were duly worked out and published in some detail.21

Singer’s implied claim to have originated the idea of a small, instrumented satellite was greeted with discomfort by much of the scientific community. As related by Homer E. Newell in his book on the early history of space science:

Members of the Upper Atmosphere Rocket Research Panel were aware of these [early military satellite] studies, but those who were employees of the military did not feel free to press the issue. As has been seen, the panel recommended only a sounding rocket program to the Academy of Sciences [for the IGY]. But geophysicist S. Fred Singer of the Applied Physics Laboratory, who had been conducting cosmic ray and magnetic field research in sounding rockets, felt under no restraints of military security. From some fairly simple calculations, Singer concluded that it should be possible to place a modest (45-kilogram) satellite in orbit around the Earth, and at every opportunity, he urged that the country undertake to do so. Singer’s conclusions were qualitatively correct, but his outspokenness generated some friction for at least two reasons. First, Singer’s manner gave the impression that the idea for such a satellite was original with him, whereas behind the scenes many had already had the idea, and they felt that Singer had to be aware of this. Muzzled by classification restrictions, they could not engage Singer in debate. Second, being unable to speak out, those who had dug into the subject in much greater depth could not point out that Singer’s estimates overshot the mark somewhat, and that his suggested approach was not as workable as others that couldn’t be mentioned.22

Singer continued to press his ideas for the MOUSE. His next step was also chron­icled by Newell:

Singer gained international attention for his proposal when, in August 1953 at the Fourth International Congress on Astronautics in Zurich, he described his idea for a Minimum Orbital Unmanned Satellite Experiment, which he called MOUSE. MOUSE would weigh 45 kilograms, and would be instrumented for scientific research.

The International Scientific Radio Union, at its 11th General Assembly in The Hague, gave support to Singer’s proposal. At the urging of both Singer and Lloyd Berkner, on 2 September 1954 the Radio Union [International Scientific Radio Union, or URSI] adopted a resolution drawing attention to the value of instrumented earth satellites for solar and geophysical observations. Later that month, on 20 September, the International Union of Geodesy and Geophysics [IUGG] at its 10th General Assembly in Rome adopted an even stronger resolution, actually recommending that consideration be given to the use of small scientific satellites for geophysical research. Both the resolution of the Union of Geodesy and Geophysics and the earlier one of the Radio Union were conveyed to CSAGI, which held its third general planning meeting in Rome shortly after the close of the Geodesy and Geophysics Union meeting.23

The URSI resolution recognized “the extreme importance of continuous obser­vations from above the E-region of extra-terrestrial radiations, especially during the forthcoming IGY.” It went on to state, “URSI therefore draws attention to the fact that an extension of present isolated rocket observations by means of instrumented

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Earth satellite vehicles would allow the continuous monitoring of solar ultra-violet and X-radiation intensity and its effects on the ionosphere, particularly during solar flares, thereby greatly enhancing our scientific knowledge of the outer atmosphere.”24

The CSAGI satellite challenge The IUGG quickly followed that resolution with an even stronger formal resolution. It was presented to the CSAGI for action, and on 4 October 1954, the CSAGI passed a very slightly edited version of the IUGG resolution. It read:

In view of the great importance of observations during extended periods of time of extra­terrestrial radiations and geophysical phenomena in the upper atmosphere, and in view of the advanced state of present rocket techniques, the CSAGI recommends that thought be given to the launching of small satellite vehicles, to their scientific instrumentation, and to the new problems associated with satellite experiments, such as power supply, telemetering, and orientation of the vehicle.25

That resolution officially introduced the prospect of artificial Earth satellites into the planning for the IGY program. Exactly three years later, the first satellite was launched.

The U. S. response to the challenge The U. S. response to the CSAGI challenge took some time. Homer Newell’s excellent account of this history reads:

The U. S. National Committee for the IGY gave careful consideration to the proposal during the spring of 1955. Support was not immediately unanimous. Clearly the dimensions of this undertaking would be of a different order from the sounding rockets already a part of the IGY planning. Doubts were expressed over the wisdom of including the project in the IGY. Technical aspects were not the only considerations. There was also the concern about what would be the reaction of people to the launching of an artificial satellite that could easily be viewed as an eye in the sky, could well be accorded some sinister import, perhaps even be equated with some kind of witchcraft. Memories of Orson Welles’s Mars invasion had by no means vanished. Most, however, favored endorsing the project. Joseph Kaplan, chairman of the committee, was especially enthusiastic and jokingly coined the phrase “Long Playing Rocket” for the satellite, by analogy with the long-playing records newly on the market. He suggested that, since sounding rockets had become familiar, the idea of a long-playing rocket would prove less disturbing than the completely new concept of an artificial satellite.26

Eventually, the National Academy of Sciences (as sponsor of the U. S. IGY program) and the National Science Foundation (which provided the money) sought approval of a U. S. Earth satellite program. On 29 July 1955, President Dwight D. Eisenhower announced the decision to launch “small, unmanned, Earth-circling satellites as a part of the U. S. participation in the IGY.” That announcement was made simultaneously in Washington, D. C.; in Brussels, Belgium, at a meeting of the CSAGI in the marble great hall of the Academy Palace; and in the 40 countries participating in the IGY.27 With that announcement, organizing the U. S. program shifted into high gear.

The three U. S. armed forces vied for the assignment to plan and execute the satellite technical program. Through a process described in detail in Chapter 7,

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Подпись:that responsibility was ultimately assigned by the Secretary of Defense to the Navy Department on 9 September 1955. In turn, the navy secretary assigned it to the Chief of Naval Research on 27 September, and the director of the NRL was given the task of executing it on 6 October.

The National Academy of Sciences retained the responsibility for policy guidance and for interfacing with the various individuals and organizations of the IGY. That responsibility included the prioritization and selection of the experiments.

In early October 1955, the U. S. National Committee for the IGY established a Technical Panel on the Earth Satellite Program, with Richard W. Porter as chairman. It held its first meeting on 20 October. In late January 1956, Porter asked Van Allen to chair a new Working Group on Internal Instrumentation (WGII). At the same time, he asked William H. Pickering to set up a companion Working Group on External Instrumentation (WGEI). The WGII was concerned with the scientific instruments to be flown, while the WGEI dealt with telemetry and tracking. All three groups undertook their work with great alacrity.

In the final analysis, it is virtually certain that the perceived need to develop a U. S. satellite for military needs served as a significant factor in gaining administration support for the IGY satellite effort. The IGY provided a convenient “open, pure science” cover that helped to ensure that U. S. satellites would be accepted in the international political arena.

Initial official soviet actions Although Soviet interest in space flight was also long­standing, the Soviets were slower to reveal their thinking to the outside world in any formal sense. As mentioned earlier, by the time of the 20 September 1954 meeting of the IUGG, the USSR had not even officially committed to participating in the IGY. By early 1956, that commitment had been made, and their IGY Committee was invited by a special letter from the CSAGI secretary-general, Marcel Nicolet, to consider participating in the rockets and satellites program.

Although the invitation was apparently received with great interest in the Soviet Union, no formal announcement of Soviet plans to launch an Earth satellite was made to the outside world until that fall. On 11 September 1956, Academician Ivan P. Bardin announced to the delegates at the Fourth General Assembly of the CSAGI in Barcelona that the USSR would have a rocket program in the IGY and “would use satellites for pressure, temperature, cosmic ray, micrometeor, and solar radiation measurements.”

It was not until 10 June 1957 that Bardin revealed any further details about the Soviet program to the IGY planners. This was done via letter to the CSAGI Reporter on Rockets and Satellites. In that letter, he mentioned that 125 meteorological rockets would be launched from the Arctic, central USSR, and Antarctic. He also mentioned

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the satellites again, stating that all of the rocket and satellite launches would study “the structure of the atmosphere, cosmic rays, the ionosphere, micrometeors and meteorites, the physical and chemical properties of the upper astrosphere, and more.” But other details, such as the number of planned satellite launches and their sizes, were not revealed.

Although I did not attend the CSAGI and other early international IGY planning meetings, I did observe and participate in much of the detailed planning for the U. S. IGY satellite program throughout 1956 and 1957. The information above was the limit of my knowledge about the Soviet intentions, and I believe that was true for the majority of civilian scientists involved in the U. S. program. We were largely unaware of the many other indicators of Soviet space activity that are detailed in Chapter 6.

The U. S. Vanguard Satellite Program Once the NRL received the assignment for developing the U. S. satellite in early October 1955, work quickly accelerated. The first substantive outline of the form of the U. S. satellite (by that time known as Vanguard) was presented in late November by Homer Newell to the Technical Panel on the Earth Satellite Program.28 He stated that the NRL concept employed two concentric spheres: an outer one, to be 20 or 30 inches in diameter, and an internal, 12 inch diameter sphere to house most of the scientific instruments. The shape of the outer sphere was chosen to optimize optical tracking and the conduct of scientific experiments related to atmospheric drag. Although it was thought then that the inner container should be spherical to help in controlling the temperature of the internal instruments, later study allowed it to be changed to a cylindrical form that permitted more efficient packaging.29

In that early concept, each of the two spheres was to be pressurized independently with helium, although the satellite was to be able to operate even if pressure in the outer sphere was lost due to punctures by small particles (micrometeorites) that were expected to be present in orbit.

That early design posited a total satellite weight of about 22 pounds, with about 2.2 pounds available for scientific instruments, exclusive of telemetry and batteries. It was stated that the data would be recovered by the Minitrack tracking and telemetry system then being developed at NRL under John T. Mengel’s leadership. The antici­pated periods of usable data reception during passage over each ground station were expected to be from eight seconds to as long as a minute for transits that passed directly overhead.

Some of the U. S. scientists were greatly troubled by the small instrument weight allocation. Van Allen suggested during January 1956 that the project consider making some of the satellites cylindrical in shape, with a length of about 18 inches and a diameter of 6 inches. He referred to this as the Mark II configuration.30 The intent of his recommendation was to make more of the total satellite weight available for

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Подпись:scientific instrumentation. It should be noted that the Mark II configuration was similar to the satellites that were ultimately launched as the early Explorers.

Some of Van Allen’s preference for the six inch diameter, no doubt, resulted from our group’s experience with that size for the Deacon-based rockoon instruments. And, although he could not discuss it in the unclassified sessions, it is likely that his preference was also strongly influenced by his knowledge of the highly classified Jupiter C developments then under way at the Army Ballistic Missile Agency at Huntsville, Alabama. Van Allen became aware of those developments as early as 1954, when Ernst Stuhlinger, from the Huntsville team, told him of the possibility that the Army might be able to launch a satellite with its rockets. It had been, in fact, that knowledge that most directly motivated Van Allen to prepare his first (November 1954) proposal for a satellite-borne cosmic ray instrument. That background is described in greater detail in Chapter 7.

Major progress had been made in the Vanguard planning by early February 1956. The diameter of the outer shell was set at about 20 inches, in order that it would fall within the envelope of the third stage of the proposed Vanguard launch vehicle. In addition, the configuration for the inner instrument package was changed to a 3.5 inch diameter cylinder with a variable length, depending on the instruments. The satellite maximum weight had been set at 21.5 pounds, with 2 pounds allocated for the experimenters’ instruments (again, exclusive of telemetry and batteries).31

The issue of the satellite configuration remained open for some time. As late as 30 May 1956, two weight breakdowns were still being carried: one for the spherical form favored by NRL and the other for the cylindrical form preferred by Van Allen and several others.32

The issue was finally settled by a compromise of sorts. The outer shell for all the satellites would remain spherical with a diameter of 20 inches, but the specifications for the inner package were amended to permit either a 3.5 inch or a 6 inch diameter instrument cylinder. Although that did not make as much weight available for the scientific instruments as the Mark II configuration would have provided, the 6 inch instrument configuration did permit more efficient packaging.

The Vanguard satellite hardware Upon receiving approval of the Vanguard project in early October 1955, NRL began working diligently to develop the satellite’s shells, thermal control systems, transistor circuitry, telemetry and tracking systems, and other capabilities that would be required. Progress on those fronts (as well as on the launch vehicle and other Vanguard components) is recorded in a series of 36 detailed reports, the first one dated 13 January 1956. In their third report, dated 29 March 1956, they outlined three satellite designs. They were described as follows:

(1) A minimum-weight satellite containing only Minitrack equipment—the size and

shape would be consistent with the equipment and weight requirements. From a weight

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standpoint, it would be preferable to attach the sphere solidly to the third-stage shell and omit spin-isolation bearings and separating devices. The temperature and acceleration effects on the structure and equipment are being investigated. The weight of this satellite might be as little as eight pounds; it would not be more than eleven pounds.

(2) A 20-inch spherical satellite weighting 21.5 pounds—it would contain a Minitrack and telemetering transmitter; temperature, pressure, and erosion gauges; and equipment for the measurement of variations in solar Lyman-alpha radiation. It would be mounted on a bearing to reduce the spin rate, and a separating mechanism would cause the satellite to leave the third-stage case at about five feet per second after burnout.

(3) A satellite which would contain the same instrumentation as (2), but might remain attached to the third-stage case and would have an optimum configuration which has not yet been established.

The final choice of the satellite type will be made at a future date.33

The planning, then, was that the first small (six inch) satellites would be built for test vehicle developmental launches, while either the second or third configuration would serve as the full IGY scientific instrument-carrying satellite.

The small satellite was, in fact, placed atop test vehicles (TVs) TV-3 (unsuccessfully attempted on 6 December 1957), TV-3BU (unsuccessfully attempted on 5 February 1958), and TV-4 (successfully launched as Vanguard I on 17 March 1958).34 The third design listed above was dropped fairly early in the program.

The second design evolved into the configuration that was ultimately used for six all-up IGY launch attempts, beginning with the (unsuccessful) launch of TV-5 on 28 April 1958. The one successfully launched on 17 February 1959 atop Satellite Launch Vehicle 4 (SLV-4) was Vanguard II. Vanguard III, launched on 18 September 1959, employed a more powerful third stage, permitting a heavier satellite.

It has been reported from time to time that the small satellites included in the failed launch attempts in December 1957 and February 1958, and successfully launched as Vanguard I in March 1958, were the result of a last-minute crash effort to get a payload into orbit as quickly as possible after the Sputnik 1 launch. In fact, as stated above, the 6.44 inch diameter satellite was always planned as a part of the Vanguard launch vehicle development program.

The number of failed Vanguard vehicle launch attempts may seem excessive at first reading. But it was not so by the standards of rocket development at that time. The Vanguard, during its full development and operational period, made a total of 14 launch attempts, including both early rocket developmental tests and all-up satellite launch attempts, of which there were eight failures.

By comparison, the V-2 rockets assembled in the United States following World War II experienced 20 failures out of 64 attempts, even though thousands of the operational rockets had been launched from Germany by that time, and the U. S. operations were overseen by the German scientists who had helped design them. The development of the Redstone rocket up to its elevation to operational status included 37 test flights, of which 10 were failures. The Thor IRBM, during its developmental

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Artificial Earth satellites

TABLE 3.1 Early U. S. Launching Scorecard

Year

Successes

Failures

Percentage

Success

1957

0

1

0

1958

7

10

41

1959

11

8

58

1960

16

13

55

1961

29

12

71

1962

52

7

88

1963

38

8

83

1964

57

7

89

1965

63

7

90

1966

73

4

95

testing period, made 10 launch attempts, of which 6 were failures. The first version of the Atlas, designated Atlas-A and consisting of only the main sustainer stage with a planned range of 600 miles, experienced five failures out of eight attempts.

Table 3.1 shows the total number of U. S. space launch attempts during the first 10 years of the Space Era, and the percentage of those attempts that succeeded.

Of the eight satellite instruments that I developed at Iowa before my departure in September 1960, only half were successfully launched into orbit. The success-to – failure ratio improved slowly during the next few years. It was only in 1965 that the space launch success rate reached 90 percent.

The Soviets fared no better. The public perception of their success was better, as they hid their failures until much later. In actual fact, during the years 1957 through 1960, they made 19 launch attempts, of which only 9, or 47 percent, were successful.

Experiment selection Long before the announcement in July 1955 of a plan to launch a U. S. satellite, ideas for space-based investigations had been gestating in many minds. The president’s decision and announcement provided a great stimulus for further thinking. The first concrete experiment proposal was Van Allen’s, dated 28 September 1955, to study cosmic rays.35 It was followed a few weeks later by a proposal by Fred Singer at the University of Maryland to measure the erosion of the satellite’s skin by meteoric dust.36 And the competition for real estate on the enthusiastically anticipated satellite was off and running.

The UARRP, mentioned earlier as being formed during the V-2 rocket-launching era, had continued its activity into the IGY planning period. Following the president’s July announcement, that body quickly made concrete plans for examining potential satellite experiments. They ended their meeting on 27 October 1955 at the Ballistics Research Laboratories in Aberdeen, Maryland, with a decision to hold a symposium to discuss ideas for such experiments. The guidelines that they established for that symposium stipulated that attendance would be limited to panel members and their

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invitees, that only unclassified materials would be considered, and that the subject matter would be highly constrained to be specific, critically considered, and pertinent within the constraints of the present and near-term projection of technologies. The meeting was open for “plans for physical experiments and observations, theoretical and interpretative matters, and techniques and components of a novel nature, but not space medicine, or the legal and political aspects of the satellite program, or essays dealing with vehicle propulsion and guidance.”37

That symposium took place on the campus of the University of Michigan at Ann Arbor on 26-27 January 1956. The forty-third meeting of the UARRP, it was also billed as their Tenth Anniversary Meeting. It provided an opportunity for scientists to present their ideas for space research in an informal, collegial environment. The proposals for both passive and active satellite-based experiments encompassed a wide span of disciplines, including meteor and interplanetary dust characteristics, air pres­sure and density, hydrogen distribution, meteorological measurements, ionospheric structure, temperature, electron density, electromagnetic propagation, auroral radia­tion, magnetic field, Earth heat transfer, solar Lyman-alpha emission, solar stream particles, ultraviolet stellar magnitudes, and, of course, cosmic rays. Thirty-three of those proposals were later published in book form.38

I accompanied Van Allen to that Ann Arbor symposium. It was a watershed experience for me, as it greatly broadened my perspective of scientific research in general, and of the up-and-coming space program in particular. After that meeting (and my concurrent undergraduate graduation), and in advance of official action to select the scientific experiments to be funded by the IGY program, I began substantive work on developing Van Allen’s instrument, as related in detail in Chapter 5.

Immediately after that meeting, at the beginning of February 1956, the newly formed WGII, under Van Allen’s chairmanship, took over the responsibility for all aspects of the instrumentation to be carried on the IGY satellites, including appraising the many proposals being suggested. Initial members of that group were Leroy R. Alldredge (Johns Hopkins Operations Research Office), M. Ference (Ford Motor Company), Herbert Friedman (NRL), William (Bill) W. Kellogg (RAND), Richard Porter (General Electric), Lyman Spitzer (Princeton University), and Van Allen (as chairman).39,40

Thirty serious proposals were initially considered by the WGII. By the time of its first actual meeting on 2 March 1956, the list to be evaluated stood at 11, with 4 more needing additional clarification. They set about energetically to reduce that list to a priority-ordered list that could be flown on the six launch vehicles being procured. The four criteria on which they settled for ranking the proposals were as follows:

(a) Scientific Importance. This aspect was taken to be measured by the extent to which the proposed observations, if successful, would contribute to the clarification and understanding

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Подпись: 82of large bodies of phenomena and/or by the extent to which the proposed observations would be likely to lead to the discovery of new phenomena.

(b) Technical Feasibility. This criterion encompassed evidence for previous successful use of the proposed technique in rockets (or otherwise), apparent adaptability of the instru­mentation to the physical conditions and data transmission potentialities of presently planned satellites, nature of data to be expected, and feasibility of interpretation of observations into fundamental data.

(c) Competence. An assessment of competence of persons and agencies making pro­posals was attempted. The principal foundation for such assessment was previous record of achievement in work of the general nature proposed.

(d) Importance of a Satellite Vehicle to Proposed Work. The nature of each proposal was analyzed with respect to the questions: Is a satellite essential or very strongly desirable as a vehicle for the observing equipment proposed? Or could the observations be made nearly as well or better with balloons or conventional rockets as vehicles?41

Van Allen’s Geiger-Muller (GM) counter cosmic ray proposal was accepted on 12 May 1956 by the U. S. National Committee for the 1957-1958 IGY (see the comments in the foreword). It was placed on the short list of potential payloads for early satellite missions, and initial funding was arranged.

At its second full meeting on 1 June 1956, the WGII produced an initial constel­lation of priority-ordered Earth Satellite Proposals (ESPs) out of those that had been submitted. They were as follows:

ESP-8, Satellite Environmental Measurements, H. E. LaGow, Naval Research Laboratory.

ESP-9, Solar Lyman-Alpha Intensity, H. Friedman, Naval Research Laboratory.

ESP-11, Proposal for Cosmic Ray Observations in Earth Satellites, J. A. Van Allen, University of Iowa.

ESP-4, Proposal for the Measurement of Interplanetary Matter from the Earth Satellite,

M. Dubin, Air Force Cambridge Research Center.42

At a meeting in early December 1956, the WGII converted that list into a somewhat modified group in which some of the initial proposals were combined and several others were added. The complete list included studies in meteorology, geomagnetism, ionospheric physics, cosmic rays, meteorites, and astrophysics. They identified that list as a “hard-core program” of onboard experiments, designated them as priority-A experiments, and set the stage for their funding.

The first priority-A package included the instrument proposed by Herbert Friedman of the NRL to monitor the intensity of the solar Lyman-alpha ultraviolet emission line at 1215.7 angstroms. It employed a straightforward ionization chamber covering the range 1100 to 1400 angstroms. That primary experiment was to be accompanied by a group of measurements to determine the effectiveness of the provisions for controlling the temperature within the satellite and to measure the density of the field of micrometeorites and their effect on the outer satellite surface.

Unsuccessful attempts were made to launch that instrument on 28 April 1958 (Vanguard TV-5), 27 May 1958 (Vanguard SLV-1), and 26 June 1958 (Vanguard

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SLV-2). That set of instruments was ultimately launched on 18 September 1959 as part of a substantially expanded Vanguard III payload.

The second approved package included Van Allen’s cosmic ray instrument, con­sisting of a single GM counter coupled with onboard data storage to provide coverage over the entire geographic area covered by the satellite. The observation of cosmic ray intensity above the atmosphere was expected to reveal the geographical symmetry of the cosmic ray intensity, and the deviations of that symmetry from that of the Earth’s magnetic field. The instrument was also expected to provide a first measurement of fluctuations in the intensity of the primary cosmic rays in order to study their possi­ble sources and the process by which they reached the Earth. It was envisioned that the satellite information would supplement and extend the ground-based cosmic ray observations also being planned for the IGY. A second instrument on that package was a set of sensitive gauges on the outer skin of the satellite for determining the order of magnitude of erosion due to meteoric impacts. That instrument was proposed by Edward Manring and his group at the Air Force Cambridge Research Center in Massachusetts.

The development of the second Vanguard experiment package is the primary subject of Chapter 5.

The third priority-A package consisted of a proton precessional magnetometer to measure the Earth’s magnetic field at high altitudes and over an extended geographical area. The basic instrument, in a 13-inch diameter sphere, was reduced to flight form under James P. Heppner’s leadership at NRL. That third payload also included a 30 inch diameter inflatable sphere proposed by William J. O’Sullivan at the National Advisory Committee for Aeronautics laboratory at Langley Field, Virginia. That sphere was to be separated from the primary satellite and tracked from the ground to provide a sensitive measurement of the density of the Earth’s atmosphere at much greater heights than hitherto possible.

An unsuccessful attempt was made to launch that two-instrument package on 13 April 1959 (SLV-5). The magnetometer flew later as part of the instrument com­plement on the expanded Vanguard III on 18 September 1959. The inflatable sphere was never flown successfully in that form. A somewhat similar sphere, focused on the original objectives, was eventually launched on 16 February 1961 as Explorer 9. Two Echo satellites, launched on 12 August 1960 and 25 January 1964, used technology developed in that program.

The fourth Vanguard launch vehicle was reserved for a meteorological experiment. Two packages were developed, of which one was to be selected for flight. The first instrument was for the observation of cloud cover over a substantial portion of the Earth’s surface. Developed by William G. Stroud, William Nordberg, and their group at the U. S. Army Corps Signal Engineering Laboratories at Fort Monmouth, New Jersey, it employed two photoelectric telescopes to scan the Earth’s surface as the

OPENING SPACE RESEARCH

Подпись:satellite spun, coupled with an onboard tape recorder for data storage over the entire orbit.

An unsuccessful attempt was made to launch that package on 26 September 1958 (Vanguard SLV-3), and it was successfully orbited on 17 February 1959 as Vanguard II. Unfortunately, its scientific value was limited due to an unplanned wobble in the satellite’s spin due to tipoff by the final rocket stage.

The other meteorological experiment was developed by Verner E. Suomi, engineer Robert (Bob) Parent, and their group at the University of Wisconsin. It employed four specially prepared small spheres supported by rods around the outer equator of the satellite. Those sensors were sensitive to radiation at several different wavelengths to provide a measure of the Earth’s radiation balance, i. e., the net effect of radiation arriving from the Sun and of radiation being emitted from the Earth.

An unsuccessful attempt was made to launch the Wisconsin instrument on 22 June 1959 (Vanguard SLV-6). Although that instrument was never successfully launched as a part of the Vanguard program, it was adapted for the Explorer 7 payload that was successfully launched on 13 October 1959.

Six backup experiments were designated by the WGII, in case problems arose with the development of the primary instruments described above. Those packages were never assigned flight space as part of the Vanguard program, although many of their objectives were ultimately achieved by instruments in different forms on later spacecraft.

Building the Deal I satellite

The JPL had the overall responsibility for designing, building, and testing the Deal I instrument package that became Explorer I. Of course, they also built the upper rocket stages and the Microlock ground network.

My direct responsibility in that first satellite was for the circuit design and perfor­mance of the GM counter, its high-voltage power supply, and the associated scaler circuits. It included the full responsibility for calibrating the GM counters and for verifying the satisfactory overall performance of the scientific instrument.

Edward Manring and Maurice Dubin at the AFCRC near Boston provided the fine wire grids and microphones for detecting micrometeorites, and Temple University in Philadelphia provided the tuned microphone amplifiers for them.

The U. S. Army Signal Corps Engineering Laboratories at Fort Monmouth, un­der the arrangement that I had made with them earlier, delivered flight-qualified component kits for the high-voltage power supplies for our Geiger counters. They also provided quartz crystals for the JPL-built transmitters.

CHAPTER 8 • GO! JUPITER C, JUNO, AND DEAL I 235

By late November, JPL had set up the entire organizational structure for both the Deal I and II projects.22 It was quite a readjustment for me to shift from the environment at SUI, where I was in full control of all satellite technical activities, to that at JPL, where I was a junior engineer enmeshed in a huge organization with no clear line of authority. I had lost most of my control over what was happening to “my graduate research project.”

In actual fact, I was involved in one way or another with most of the decisions involving our instruments. As with most rush projects of this nature, a lively in­formal process operated behind the scenes, and it was usually possible for me to work directly with whomever I thought necessary. On the senior management level, I enjoyed a very pleasant and effective working relationship with JPL di­rector Bill Pickering, project director Jack Froehlich, consultant Eb Rechtin, head of satellite instrumentation Walter (Walt) Victor, head of satellite observations Al Hibbs, head of satellite and Microlock antennas Bob Stevens, and, of course, Henry Richter.

My contacts with engineers and technicians on the working level were especially memorable, and I remember many of those friends with great fondness. In addition to Henry Richter, John Collins, and Dean Slaughter, they included Bill Pilkington, Lee Randolph, and Lee Zanteson.

Going public

The forum for the public announcement of the discovery of the region of high-intensity radiation was a special meeting in the Great Hall of the National Academy of Sciences at 9:45 AM on Thursday, 1 May 1958. The meeting had been publicized within a large circle of members of the scientific community and media by two letters from Hugh Odishaw, executive director of the U. S. National Committee for the IGY. His first letter, dated 22 April and addressed to members of the U. S. National Committee and its Technical Panels, was headed “Experimental Results for 1958 Alpha.” It read:

Brief papers have been scheduled for the presentation of preliminary data obtained from US-IGY satellite 1958 Alpha. Cosmic ray, micrometeorite, temperature, and orbital data will be described by representatives of the State University of Iowa, the Geophysical Research Di­rectorate, the Jet Propulsion Laboratory, and the Naval Research Laboratory and Smithsonian Astrophysical Observatory. The papers will be presented in the Great Hall of the National Academy of Sciences, 2101 Constitution Avenue, N. W., at 9:45 a. m., Thursday, May 1. The meeting is expected to last about one hour.46

Odishaw followed that letter with a second one six days later that transmitted preliminary copies of the papers (including ours). His transmittal letter read:

As you know from my notice dated April 22, 1958, the President of the Academy has made arrangements to have briefreports on experimental results of1958 Alpha presented to members of the Academy, the American Physical Society, and the local scientific community at a special meeting in the Great Hall of the Academy at 9:45 a. m., Thursday, May 1, 1958…. The enclosures are advance copies of these preliminary reports. They are marked “Not for Release” inasmuch as the Academy is making provision for the orderly public release of the reports at the time of the special meeting noted above.47

As indicated, the session had been precipitated by Van Allen’s disclosure of our radiation belt discovery to Richard Porter and other program officials in mid-April. It

OPENING SPACE RESEARCH

Подпись:was arranged initially to provide a forum for the exchange of all experimental results obtained thus far from Explorer I, but the agenda was expanded to include some results from Explorers II and III.

Van Allen and Frank McDonald represented our Iowa group at the session. The session was chaired by Porter, in his capacity as chairman of the Technical Panel on the Earth Satellite Program (TPESP), U. S. National Committee for the IGY. The papers were titled as follows48:

Status Reports on Optical Observations of Satellites 1958 Alpha [Explorer I] and 1958 Beta [Explorer II], by J. Allen Hynek and Fred L. Whipple

Scientific Results: The Orbit and Variable Acceleration of Satellite 1958 Alpha, by Charles A. Whitney

The Density of the Upper Atmosphere, by Theodore E. Sterne

The Determination of the Orbit of 1958 Alpha at the Vanguard Computing Center, by Joseph W. Siry

Satellite Micrometeorite Measurements, by E. Manring and M. Dubin Satellite Temperature Measurements for 1958 Alpha—Explorer I, by E. P. Buwalda and A. R. Hibbs

Observation of High Intensity Radiation by Satellites 1958 Alpha and Gamma, by James A. Van Allen, G. H. Ludwig, E. C. Ray, and C. E. McIlwain

The last paper received the most attention—our paper disclosing the discovery of the region of high-intensity radiation. In his oral presentation, Van Allen followed the general structure of our written report, but with substantial elaboration. At the end, he added a discussion of the possible relationship between the radiation seen by the satellites and that detected earlier on Iowa’s Davis Strait rockoon expeditions, on Carl McIlwain’s Fort Churchill rocket flights, and on high-altitude balloon flights. Specifically, paraphrasing his spoken word, Van asserted that the effect must be due to charged particles (as opposed to neutral particles or photons), that it was likely to be bremsstrahlung from electrons confined by the Earth’s magnetic field, and that those electrons were rather closely related to the soft radiation that had earlier been observed in the polar regions.

He sketched some numbers on the blackboard, from which he made a further speculation that, if the particle identification were correct, the flux of electrons must be of the order of 109 per square centimeter per second, that the average energy was of the order of 40 kilovolts, and that the energy flux was of the order of 10 ergs per square centimeter per second.

In his wrap-up, Van Allen discussed the probable relationship of those results with the general theoretical concepts of Chapman and Ferraro, including the prob­ability that the particles were trapped in Stormer-Treiman lunes about the Earth. He mentioned that the observed intensity of radiation should be a source of radio noise (probably not detectable from the ground but possibly by a vehicle above

CHAPTER 12 • DISCOVERY OF THE TRAPPED RADIATION 347

the ionosphere). He suggested that there was most likely an intimate connection between this observed radiation and the occurrence of visible aurorae, and that the radiation intensity above 1000 kilometers probably exceeded 60 milliroentgens per hour.

Van Allen’s presentation was followed by a spirited question-and-answer period that focused primarily on arguments against the observations being due to protons or gamma radiation.

Van Allen’s handwritten speaking notes are preserved in the University of Iowa Libraries.49 His entire lecture and the ensuing discussion were captured on magnetic tape by a reporter from the Voice of America, and later transcribed through the efforts of Hugh Odishaw, Ross Peavey, and John Truesdale of the U. S. IGY staff. That transcription was published as a University of Iowa Physics Department research report,50 and shortly thereafter as a National Academy of Sciences IGY Satellite Report.51

That initial announcement of the belt discovery was quickly followed by presentations in other forums. For example, Van Allen repeated his presentation at the 9-12 June 1958 semiannual meeting of the American Rocket Society in Los Angeles. Ernie Ray represented our group at the Fifth Meeting of the Special Committee for the International Geophysical Year in Moscow, held on 29 July to 9 August 1958. There, a telegram from Van Allen, McIlwain, and me conveyed an early report of Explorer IV results. He reported to the attendees that the new data confirmed our radiation belt findings from Explorers I and III.52

Other authors have published their own accounts of the Iowa radiation belt discovery over the ensuing years, of which some of the most interesting and authoritative are identified in the bibliography and in an endnote.53 Although they are in reasonably good agreement on the general sequence of events, the careful reader will note some differences. A special effort was made in this book to resolve those differences, using primary references as well as personal records and exchanges with Van Allen, McIlwain, and others.

Assembling and testing the instrument

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

Подпись: OPENING SPACE RESEARCH FIGURE 5.3 Mechanical layout of the SUI cosmic ray instrument as of the end of 1956. The diameter of the package (width in this two-dimensional drawing) was 5.5 inches, while its height (exclusive of the GM counter) was 9 11/16 inches.

138

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 139

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

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

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

• Operation in a complete vacuum

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

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

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

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

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

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

Подпись: 140OPENING SPACE RESEARCH

Assembling and testing the instrument

FIGURE 5.4 The seven-stage scaler deck, as designed for the Vanguard instrument. The mark­

ing E1 indicates that it was the first E deck built. The E deck can be seen in its place in the complete instrument drawing in Figure 5.3.

 

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

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 141

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

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

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

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

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

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

OPENING SPACE RESEARCH

Подпись: 142great confidence in their work and led, eventually, to the collaborative arrangement whereby they designed the high-voltage power supplies for the GM counters and supplied component parts kits that we assembled in the early Explorers.

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

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

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT

Assembling and testing the instrument

FIGURE 5.5 Group picture of most of the participants at the April 1957 working meeting at the NRL, taken on the entrance steps of NRL Building 43. From left to right, starting with the front row: Warren Berning, Homer Newell, Bill Stroud, James Van Allen, and Vern Suomi. Second row: Jim Heppner, Jessie Mitchel, Rudy Stampfl, Rudy Hanel, John Maskaski, and George Ludwig. Third row: Luc Secretan, identity unknown, John Licht, identity unknown, Ed Rich, and Bob Stroup. Fourth row: Roger Easton, George Hunrath, identity unknown, Hans Ziegler, Bob Baumann, and Milt Schach. Fifth row: Marty Votaw, Maurice Dubin, identity unknown, Ed Manring, Whitney Mathews, Ed Bissel, Karl Medrow, and identity unknown. (Courtesy of the Naval Research Laboratory.)

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

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

Assembling and testing the instrument Подпись: INSTRUMENTATION
Подпись: BATTERIES
Подпись: OPENING SPACE RESEARCH
Подпись: G. M, TUBE
Подпись: RECEIVER_ TRAJNSMIITER -ELECTRONICS AND TAPE " "-RECORDER"

Assembling and testing the instrumentPACKAGE

SEPARATION DEVICE

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

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT

Assembling and testing the instrument

FIGURE 5.7 Fitting the partly completed but physically realistic cosmic ray instrument package into the NRL-provided Vanguard satellite structure. The author is on the left, and Wayne Graves is holding the top half of the shell.

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

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

OPENING SPACE RESEARCH

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

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

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

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

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

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 147

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

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

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

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

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

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

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

OPENING SPACE RESEARCH

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

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

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

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 149

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

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

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

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

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

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

Assembling and testing the instrument Подпись: FIGURE 5.8 The final Mark IV data recorder, as designed for Vanguard and flown eventually in Explorers II and III. It was photographed without its cylindrical housing to show the inner works. The new-style stepper and drive ratchet are in the upper center. The small cylinder to the stepper's right on the top plate is the release solenoid, while the mechanism to the left includes the mechanical limit stops.The cylinder at the bottom contains the eddy current damper for controlling the playback speed.

OPENING SPACE RESEARCH

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

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

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

CHAPTER 5 • THE VANGUARD COSMIC RAY INSTRUMENT 151

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

A heartbreaking failed launch attempt

A satellite launch operation was (and remains today) a carefully choreographed ballet, with dozens of key performers and hundreds of supporting personnel. The common

CHAPTER 10 • DEAL II AND EXPLORERS II AND III 273

A heartbreaking failed launch attempt

FIGURE 10.4 The completed Explorer II (Deal Ila) satellite payload. (a) The cosmic ray instru­ment is exposed beside its cylindrical housing. The GM counter protrudes from the top. (b) The fully stacked satellite payload, with its outer shell and cone removed to show the complete struc­ture. The cosmic ray instrument cylinder is mounted atop the bottom antenna insulator gap. The low-power assembly, with its antenna gap, ring of batteries, and central electronics stack, appears above the GM counter. The aluminum ring at the bottom of the lower antenna gap served as the threaded attachment to the fourth rocket stage. Explorer III (Deal IIb) looked the same, except that the antenna whips at the bottom were eliminated. (Courtesy of NASA/Jet Propulsion Laboratory, California Institute ofTechnology.)

media portrayal of countdowns, with their final “three-two-one” and terse “liftoff,” is the climax of an extremely long and arduous process. Each tiny action is minutely defined, timed, and documented ahead of time, and many detailed lists of steps (countdown lists) are assembled and pretested. Each such list terminates in a go/no – go decision, and all lists are linked to form the whole. For the Deal II launch there were, in addition to the master countdown conducted by the launch director in the blockhouse, separate countdowns for activating the blockhouse, activating the launch pad, activating each of the rocket subsystems, fueling, and so on. Closer to my own area of activity, there were countdowns for the final preparation of the satellite instrument package, for attaching it to the final rocket stage, for activating the backup Spare Payload in case it was needed at the last moment, for readying the Microlock ground station, for activating the interrogation ground transmitter, and so on. Just one, the countdown list for preparing the payload for its mating to the final rocket stage, occupied a number of pages.

OPENING SPACE RESEARCH

Подпись:For rocket launches until the time of the later, much more massive Saturn 5 Moon rockets, the launch activities were centered in blockhouses near the pads. Those were an outgrowth of simple barriers used during the 1920s, 1930s, and 1940s to protect launch crews from possible explosions and other mishaps. The blockhouse used for the Jupiter C launches was representative of those employed during that period. It was located only a few hundred feet from the launch pad so that the two sites could be coupled through conduits and tunnels by hundreds of wires carrying power, control, and monitoring signals.

The blockhouse was dome shaped, with a very thick concrete and earth-covered shell to protect against direct impacts of wayward rockets. It was sealed against liquids and fumes in case the rocket’s load of fuel should spill on its top and ignite. Massive blast doors were sealed before liftoff, and the heating and air-conditioning systems were closed off from the outside world. The entire complex was switched over to internal electrical power generators to guard against failure of the main Cape Canaveral power or severance of the supply lines. The blockhouse was as nearly self-sufficient as it was possible to make it.

As the director of Von Braun’s Launch Operations Laboratory at Cape Canaveral, Kurt Debus served as the launch director for ABMA launches during that period. For the Deal II launch, he was at his usual station in the blockhouse, where he could have eye contact with all of the senior engineers at their separate launch consoles. He was one of the few who could actually see the rocket through one of the periscopes that poked through the roof of the blockhouse. For this launch, Von Braun was at his favorite blockhouse observation post, with his own periscope. I was located in the rear of the blockhouse at a rack of equipment that received and displayed the signals as they were received from the satellite payload. We were all able to switch our earphones between several special telephone and intercom circuits. One permitted those of us monitoring the instrument to talk to crews at the Microlock receiving station in its trailer some distance away, to the RIG site where the command transmitter was located, and to other locations. A narrator kept all apprised of progress via a public address system.

Unlike the Deal I situation, I was fully integrated into the prelaunch activities for Deal II. Of course, the JPL payload manager had the overall responsibility for the satellite payload, but I was directly involved in all decisions dealing with the performance of the cosmic ray instrument. I monitored every step of the payload assembly and checkout, performed numerous counting rate checks, and read and evaluated the many tape recordings of our instrument’s signals.

My journal entry at 4:20 AM on 5 March 1958 stated:

Have the [blockhouse] equipment turned on. Payload activation in 40 minutes. Sky is light cloudy and broken—rather high. This is the day for which I have been working since January

CHAPTER 10 • DEAL II AND EXPLORERS II AND III 275

1956. If successful, this is to provide my Ph. D. dissertation. I’ll have to give that payload a

goodbye pat.10

There were some difficulties during the countdown. At a check at X – 300 minutes, the onboard tape recorder double-stepped. That is, for each drive pulse, the recorder tape advanced two steps. All later operation was normal in that regard.

The most serious problem was the difficulty in commanding playback of the tape recorder during the final countdown. When spin-up of the upper rocket stages was started at X – 11 minutes, the recorder operated normally. But when the spin rate reached 550 rpm, we were unable to command playback. The launch director interrupted the spin-up, slowed the rotating tub, and then had its rate increased gradually. Playback was successful at 450 rpm but not at 500.

All of that occurred within the final few minutes of the countdown, while the rocket sat there fully fueled and ready to go. The pressure for a final go/no – go decision was intense, as further delay would have meant canceling the launch for that evening and recycling for the following day or later. While we held up the launch for 18 minutes, the payload manager, other payload engineers, and I had a lively discussion and concluded that the problem was with the on – pad commanding link, not with the recorder itself. Specifically, we believed that there was a problem with the grounding path for the interrogating signal and that operation would be normal once the rocket was free of the cluttered pad environment. I gave my go-ahead based on that assessment, and the countdown continued.

The official launch time was 1:28 PM EST on Wednesday, 5 March 1958. At my post in the blockhouse, I monitored the signal from the cosmic ray counter until it faded out downrange.

Later analyses indicated that the firing of stages one, two, and three were all nor­mal. However, the fourth stage apparently failed to ignite, for reasons that were never completely determined, and the launch attempt failed. The satellite pay­load plummeted into the Atlantic Ocean about 1900 miles downrange from Cape Canaveral.11

As the payload passed over the island of Antigua, British West Indies, that station attempted to interrogate the onboard tape recorder to reset the tape to its starting point in preparation for the first orbit. That interrogation attempt failed to elicit a response. We were never able to ascertain whether that was because of a failure of the onboard instrument, a problem with the ground station, or the result of some catastrophic failure of the final rocket stage.

Even though it did not go into orbit, the payload received an Explorer II designation.

OPENING SPACE RESEARCH

Argus results

Results related to the Argus experiment were released in two phases: an early Top Secret exchange within a small circle of appropriately cleared individuals, followed later by an unclassified public release. The initial discussions were to help determine the effectiveness of the nuclear detonations in injecting electrons into the Earth’s magnetic field. That was, after all, the primary purpose of the Argus exercise. Although a broad assortment of rocket, aircraft, and ground measurements was made, it was the results from Explorer IV that were the most eagerly awaited.

Classified early discussions As mentioned before, there were four fairly high alti­tude nuclear detonations before the first Argus test. The first was Operation Teapot’s high-altitude shot at about eight miles height in April 1955 to investigate atmospheric effects. Obviously, it was too low to figure in the trapped radiation study. Operation Hardtack I, consisting of 35 tests, was conducted between 28 April and 18 August 1958. Although most of the Hardtack I tests were conducted near the surface or un­derwater at Bikini Atoll and Eniwetok Island in the central Pacific Ocean, three were designed especially to investigate effects within the high atmosphere.

The first of those, Yucca on 28 April 1958, was a balloon-lofted detonation at only about 16 miles altitude, again, too low to be useful in looking for Argus-like effects. The other two, launched by Redstone rockets to a much higher altitude from a pad on Johnston Atoll, were Teak on 1 August 1958 (48 miles high) and Orange on 12 August 1958 (27 miles). Those bursts produced effects widely seen on the ground. The Teak event was observed by a group of New Zealanders at the Apia Observatory in Samoa as a flat, horizontal arc of bright violet rays in their western sky. The display lasted about 14 minutes, shrinking and gradually changing in color to red and finally to green. Fourteen days later, they saw similar results from the Orange blast. For that one, they reported that 10 minutes after the initial flash, the sky looked like a dawn on an overcast morning. The New Zealanders quickly connected the observations with the hydrogen bomb explosions above Johnston Atoll, located over 2000 miles to their north.

The Teak flash, being the higher of the two, was clearly seen from Hawaii, some 800 miles to its northeast. Even though the actual burst was below the horizon from

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 381

Hawaii, the flash in the sky was bright enough to be seen, and the fireball rising above the horizon was photographed. The event also produced a magnetic storm that resulted in radio blackouts that persisted for nine hours in Australia and at least two hours in Hawaii. This was a result, primarily, of the introduction of a large amount of fission debris into the ionosphere, which prevented the normal reflection of radio waves back to the Earth.

The Orange shot, being at a somewhat lower altitude, was seen in Hawaii, but it did not have as much effect on communications.

Explorer IV was in orbit at the times of the Teak and Orange blasts. Despite the high yields of those blasts (3.8 megatons), they produced only small increases in the population of trapped particles at the satellite altitudes. Furthermore, since the blasts were low enough that atmospheric absorption played a major role, the effects persisted for only a few days.26

The three Argus blasts were made at much higher altitudes and in the region over the South Atlantic where the asymmetry of the Earth’s magnetic field causes the trapping region to dip to its lowest height.

Very pronounced effects from the blasts were seen by the Explorer IV instruments, as well by instruments on the ground, aircraft, and rockets. Qualitative and quantitative results from interpretation of the satellite data were provided by our Iowa group to the other Argus Project participants as quickly as they became available. It was eventually deduced that about 3 percent of the electrons from the blasts were injected into durably trapped trajectories. The mean lifetime of the artificially produced shells was about three weeks from the first two of the Argus blasts and about a month for the third. The four detectors on the satellite also revealed that the physical nature of the artificially created shells was substantially different from that of the naturally occurring belts, thus dispelling all previous thoughts that the natural belts might have been created by Soviet high-altitude nuclear detonations.

Still under a strict secrecy umbrella, a 10 day workshop on the interpretation of all Argus observations was conducted at the Lawrence Livermore Radiation Laboratory in February 1959. Van Allen and Carl McIlwain attended from Iowa. At that workshop, many of the general principles of geomagnetic trapping were substantially clarified.

But a puzzle remained. Why did the thin shells of trapped electrons produced by the blasts remain so thin over time? The Earth’s actual magnetic field differs from the shape of a dipole field that might be produced by a simple bar magnet. That was initially expected to result in a radial spreading of the thin shells.

Theoretical physicist Theodore (Ted) G. Northrup at the LLNL, at the urging of Edward Teller, had been working on the problem of longitudinal drift of charged particles in the Earth’s magnetic field. He had found an important key, a so-called longitudinal invariant. At the workshop, he described his work at an impromptu

OPENING SPACE RESEARCH

Подпись:seminar for Van Allen, McIlwain, and several others. That train of discussion led to several theorems that greatly simplified the problem of particle drift. Among other things, it clarified the question of radial dispersion of the electron shell.27

Following the workshop, McIlwain devised a way of mapping the trapped radiation that greatly simplified the process of working with the data. It reduced the usual three-dimensional coordinate system used to describe the magnetic field to a two­dimensional one. That two-dimensional system became known as McIlwain’s B, L coordinate system, where B (in gauss) represents the magnitude of the magnetic field at any point in space, and L (in Earth radii) is a parameter that is approximately constant along the specific line of force that passes through that point.

The nuclear bursts had, in effect, provided markers on magnetic shells that permit­ted the rigorous testing of Carl’s system. In that manner, Explorer IV provided a firm observational basis for the B, L coordinate system. That system, and variations of it, has been used ever since in the study of magnetic trapping in the neighborhood of celestial bodies.

It should be noted that the possibility of electronic devices being damaged by nuclear detonations well above the atmosphere was later fully validated. Operation Starfish Prime, conducted by the United States on 9 July 1962, included the detonation of a W49 thermonuclear warhead about 250 miles above Johnston Atoll in the Pacific Ocean. The burst produced an equivalent yield of 1.4 megatons of TNT. It resulted in immediate damage to three low-orbit Earth satellites and damage to a number of others over a period of several weeks.

In addition, it produced major ground effects at Hawaii andNew Zealand, including interference with radios and television sets, the fusing of 300 streetlights on Oahu, the setting off of at least 100 burglar alarms, and the failure of a microwave repeating station on Kauai that cut off telephone service with the other Hawaiian islands.

In addition to the three Argus and one Starfish detonations by the United States mentioned so far, the Soviets produced substantial effects somewhat later with three high-altitude detonations as part of their K Project. Shots K-3, K-4, and K-5 were conducted in October and November 1962. Although the blast yields were only about one-fourth that of Starfish, the tests were conducted above a populated land mass, so that the damage was apparently much greater than that caused by Starfish. The electromagnetic pulse from one of them (K-3, Soviet nuclear test number 184 on 22 October) reportedly fused 350 miles of overhead telephone lines with a measured current of 2500 amperes, induced an electrical current surge in a long underground power line that caused a fire in a power plant in the city of Karaganda, and shut down 620 miles of shallow-buried power cables between Astana and Almaty.28

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 383

Declassification Although the Argus Project was highly classified throughout its planning stage and during the first months after the nuclear detonations, that status could not be maintained indefinitely. A number of factors argued for early declassification. First was that the possibility of artificially injecting charged particles into the Earth’s magnetic field had already occurred to others. Second was that many effects of the high-altitude nuclear detonations were observable worldwide. Third was the probability that Soviet receiving stations were receiving the transmissions from Explorer IV and would be able to see effects of the nuclear blasts directly from that source.

A final factor was the fact that Explorer IV had been widely advertised as a component of the U. S. participation in the IGY, arranged to follow up on the radiation belt discovery. A very basic tenet of the IGY program was that all of its data would be released quickly for use by the entire research community. Although an attempt was made to argue that the IGY data policy did not apply to the Argus-related data, that distinction between the unclassified and classified missions was obviously thin and would be widely challenged.

To elaborate on several of those points, the idea of detonating a nuclear bomb in space as an experiment in electron trapping developed in the summer of 1958 com­pletely independently of the Argus Project, in a totally unclassified environment. Two researchers at the University of Minnesota, Edward Ney and Paul Kellogg, upon hearing of the Earth’s newly discovered trapped radiation in May 1958, suggested that a nuclear device might be detonated some 250 miles high near the southern auroral zone to see what effect it would have on the radiation belt. They figured that it might produce an effect in the Earth’s magnetic field that would “jar loose” trapped electrons, resulting in artificially created auroras in the north and south auroral zones. At the same time, they posited that particles produced by the bomb blast might be injected into the natural belt.

Those discussions took place in the absence of any knowledge by Ed and Paul of the Argus Project. When they first outlined their idea to friends in the Office of Naval Research in Washington, they received an unexpectedly cool reaction. Instead of greeting the suggestion as an interesting prospect for an IGY experiment, the Washington contacts asked that the pair not discuss their idea with anyone. The two drafted a letter to Herbert F. York, by then the chief scientist of the newly formed Advanced Research Projects Agency. They quickly learned that their letter would most likely be classified secret if sent. So they did not send it, but they decided to publish the idea in the British scientific journal Nature. When the Pentagon learned of that, their initial consternation changed to full-blown alarm. Ed and Paul were swayed to hold off on further discussions of their idea for a while. They kept the idea

OPENING SPACE RESEARCH

Подпись:quiet until February 1959, when they finally published their idea in modified form in Nature a short time before the Argus Project was officially declassified.

The idea of injecting charged particles into the Earth’s magnetic field by nuclear detonations did, as it turned out, also occur independently to the Soviets. It is unknown when the idea first occurred to them—it might have been either before or after they learned of our discovery of the region of high-intensity radiation. The idea was certainly well established by 8 March 1959, when several Soviet scientists voiced their thoughts on the subject in a newspaper release.29 Their suspicion apparently resulted from their study of the widely reported visual and electromagnetic effects produced by the Teak and Orange nuclear bursts during the previous August. The article appeared well before the Argus Project was declassified.

The Soviets also had ample opportunity to see the results of the Argus tests by receiving the Explorer IV signals at their receiving stations. On one specific occasion, as Explorer IV was transiting one of the Argus-generated shells, it was easily within range of their Tashkent receiving station.

Walter S. Sullivan was a distinguished science reporter for the New York Times for many years. During the IGY, his primary assignment was to report on its activities. From that vantage point, he played a significant role in publicizing the Argus Project and its results.30

About the end of June 1958, Hanson W. Baldwin, military analyst for the Times, somehow learned of the Argus Project. In a private conversation, he told Sullivan of the plans, stating that he had obtained the information in a manner that placed no limit on its use. However, both had misgivings about releasing the information. Sullivan prepared a summary sheet containing many of the key points about the operation, including the location, height, and yield of the blasts. He carried that information to a friend who was centrally involved in the U. S. space program and knew of the Argus plans. That friend was both horrified and amused upon reading the summary. He told Sullivan, “I can’t tell you not to print it, but I can say this: If you do, the operation will never take place.”31

The next day, Sullivan received a call from the security chief in the Pentagon’s Advanced Research Project Agency, who pleaded with him not to publish the infor­mation. Sullivan and Baldwin agreed to hold the story under wraps until after the firing—they dutifully kept that secret for more than eight months.

Sullivan had been led to believe initially that the project would be declassified soon after the blasts occurred. As the months passed, however, and no announcement was forthcoming, he became apprehensive that he might be scooped on a very important story. After all, by then, literally thousands of individuals, including the many ship crew members who participated, were well aware of the tests. He also believed that the scientific brilliance of the experiment might be eclipsed by prolonged secrecy.

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 385

With time, additional hints surfaced. On 28 November 1958, Christofilos presented his calculations on how an electron shield could be placed around the Earth at a meeting of the American Physical Society. To avoid a violation of security, he made no mention of atomic bombs as the source of the electrons but suggested that an electron accelerator in a satellite could provide them.

In a report released on 26 December 1958, Hugh Odishaw, executive director of the U. S. IGY program, called attention to some of the information then appearing in the news that suggested that the Teak and Orange blasts had caused widespread effects in and above the atmosphere.

The following day, Fred Singer presented a paper, “Artificial Modification of the Earth’s Radiation Belt,” at a session of the American Astronautical Society. In that paper, however, Fred made no direct reference to the Argus Project or its results.

During that same meeting, Van Allen described the unclassified findings from Explorer IV and Pioneer 3 that showed that there were two separate radiation belts. At a press conference following the presentation, Van Allen was asked a very pointed question by a Newsweek reporter, who wanted to know if the John­ston Atoll detonations (Teak and Orange) had produced any measurable effect in the Explorer IV data. Van Allen replied that the effect had not only been seen but was “tremendous.”

Sullivan grew increasingly agitated. After that meeting, he talked quietly with other individuals about releasing his story. Finally, on 2 February 1959, he was able to present his arguments to James R. Killian Jr., the special assistant for Science and Technology to President Dwight D. Eisenhower, telling him that he doubted that he could withhold publication of at least a limited account of Argus for much longer.

Killian’s response was that disclosure at that time might imperil the then ongoing Geneva talks on a nuclear weapons test suspension. He feared that the Soviets would be handed the argument that the only untrustworthy participant in the talks was the one that had sneaked off to fire atomic bombs far from its own shores. Sullivan continued to sit on his story.

In late February, a highly classified 10 day meeting was held at the Lawrence Livermore Radiation Laboratory to discuss Argus results, as mentioned earlier. It included an extended discussion of the need to keep the Argus program classified. The arguments were, at times, heated, with the one side saying that the tests were made at great public expense and that the United States should reap its strategic benefits for as long as possible. The counterargument, primarily by the participating scientists, was that they had been party to a magnificent physical experiment, of which their country should be proud.

Sullivan learned in mid-March that some plans for a limited disclosure were being made with at least some Pentagon backing. With that knowledge, and fearing that the

OPENING SPACE RESEARCH

Подпись:movement might gather steam and leave the Times sitting in the dust, he escalated his arguments on 16 March to the top officers of his newspaper. He soon received agreement that he could proceed, but not if the White House called and argued that the story would do serious damage to the United States. To Sullivan’s great relief, that call never came.

Public announcements of Argus Results Walter Sullivan’s first account of the Argus Project appeared in the New York Times a few days later (on 19 March 1959) under the banner “U. S. Atom Blasts 300 Miles up Mar Radar, Snag Missile Plan; Called ‘Greatest Experiment.’” His account was released by wire before press time, and many other newspapers carried the news that morning.

One week after the Times story, James C. Hagerty, press secretary to the president, provided a press release that outlined the Argus experiment and its results in con­siderable detail, and he laid out plans for a major public symposium to discuss them further.

That White House press release, prepared jointly by the President’s Science Advi­sory Committee and the National Academy of Science’s IGY Committee, in addition to providing considerable information about the Argus concept and project, provided a broad outline of many of the experimental results:

A fascinating sequence of observations was obtained. The brilliant initial flash of the burst was succeeded by a fainter but persistent auroral luminescence in the atmosphere extending upwards and downwards along the magnetic line of force through the burst point. Almost simultaneously at the point where this line of force returns to the Earth’s atmosphere in the northern hemisphere—the so-called conjugate point—near the Azores Islands, a bright auroral glow appeared in the sky and was observed from aircraft previously stationed there in anticipation of the event, and the complex series of recordings began. For the first time in history measured geophysical phenomena on a world-wide scale were being related to a quantitatively known cause—namely, the injection into the Earth’s magnetic field of a known quantity of electrons of known energies at a known position and at a known time.

The diverse radiation instruments in Explorer IV recorded and reported to ground stations the absolute intensity and position of this shell of high energy electrons on its passes through the shell shortly after the bursts. The satellite continued to lace back and forth through the man-made shell of trapped radiation hour after hour and day after day. The physical shape and position of the shell were accurately plotted out and the decay of intensity was observed. Moreover, the angular distribution of the radiation shell of the Earth’s magnetic field was being plotted out for the first time by experimental means. In their helical excursions within this shell the trapped electrons were traveling vast distances and were following the magnetic field pattern out to altitudes of over 4,000 miles. The rate of decay of electron density as a function of altitude provided new information on the density of the remote upper atmosphere since atmospheric scattering was the dominant mechanism for loss of particles. Moreover, continuing observation of the thickness of the shell served to answer the vital question as to the rate of diffusion of trapped particles transverse to the shell. All of these matters were of essential importance in a thorough understanding of the dynamics of the natural radiation and were not the subject of direct study by means of the “labeled” electrons released from Argus I.

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V

Throughout the testing period the planned series of firings of high altitude sounding rockets was carried out with full success and with valuable results in the lower fringes of the trapping region.

Explorer IV continued to observe the artificially injected electrons from the Argus tests, making some 250 transits of the shell, until exhaustion of its batteries in latter September, though by that time the intensity had become barely observable above the background of natural radiation at the altitudes covered by the orbit of this satellite.

It appears likely, however, that the deep space probe Pioneer III detected a small residuum of the Argus effect at very high altitudes on December 6, 1958. But the effect appears to have become unobservable before the flight of Pioneer IV on March 3, 1959.

The site of the Argus tests was such as to place the artificially injected radiation shell in a region where the intensity of the natural radiation had a relative minimum. If the bursts had been produced at either higher or lower latitudes, the effects would have been much more difficult to detect, plot and follow reliably for long times after the blasts.

The immense body of observations has been under study and interpretation by a large number of persons for about seven months. Only now are satisfactory accounts becoming available from the participating scientists.32

The press release concluded with an announcement of the arrangements by the National Academy of Sciences for the presentation of Argus results in a special unclassified symposium at its annual meeting planned for 27-29 April 1959.

At Iowa City, while I focused primarily on preparing instruments for the next satel­lites, Van Allen and McIlwain were concentrating on writing up our Explorer IV results for the National Academy’s meeting. Our first unclassified report was soon ready.33 It began with a discussion of the background of the Argus Project, the role of Explorer IV, and the relationship between its orbit and the Argus electron shells. Figure 13.5 portrays the geometry, as shown in that paper. There would have been four intersections of each satellite orbit with the Argus shells, except for details of the geometry and data recovery. In the sample shown here, there were three full transits at positions B, C, and D. The intersection at position A did not provide a full transit because the Argus shell was at the same height as the satellite’s height (161 miles or 258 kilometers). There were other cases in which the Argus shell lay well below the satellite height at its time of closest approach. In other cases, the intersection occurred where there were no ground stations to receive the data. The actual numbers of useful full penetrations of the electron shells were 37, 39, and 88 for Argus I, II, and III, respectively.

Data from a sample receiving station transit are shown in Figure 13.6. Note that the vertical axis is logarithmic, so the counting rate covers a huge range during the time of this pass. Proceeding from the left of the chart (at 6:00 AM), the satellite was descending from the intense inner natural radiation belt and moving northward. As it moved through about 22 degrees north latitude (at about 6:08, as indicated in the figure), the Argus shell produced the sharp spikes in counting rates from the

Argus results
Argus resultsFIGURE 13.6 A plot of data from the two GM counters on Explorer IV, taken about 3.5 hours after the Argus I burst on 27 August 1958. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Libraries.)

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V 389

two counters. By about 6:10, the satellite had passed north of the Argus shell and was in the slot between the two natural radiation belts for a few minutes, and then passed through the lower fringes of the outer natural belt to produce the broad peak seen between about 6:13 and 6:23. Comparable results were seen in all four satellite detectors for all three of the Argus bursts.

The special symposium in late April 1959 titled “Scientific Effects of Artificially Introduced Radiations at High Altitudes” addressed the full range of results from the grand experiment. Christofilos outlined its concepts, including an extended discussion of the theory of trapping. Additional theoretical information was provided by Jasper A. Welch Jr. and William A. Whitaker of the Air Force Special Weapons Center at Kirtland Air Force Base, New Mexico. Sounding Rocket results were provided by a group of authors led by Lew Allen of the Air Force Special Weapons Center. Optical and electromagnetic observations were described by Philip Newman of the Air Force Cambridge Research Center and Allen M. Peterson of the Stanford Research Institute.

Van Allen presented our paper with its huge body of satellite data. He provided a preamble and a short outline of the instruments and observations, and then presented arguments for the conclusion that the observed thin electron shells were, in fact, created by the Argus bursts, and that the natural belts were not the result of previous high-altitude nuclear detonations. Those key arguments were as follows:

(a) The observed energy spectrum and the nature of the radiation [in the shells] were found to be in essential agreement with those expected for the decay electrons from fission fragments.

(b) A peak with similar characteristics was found at every observed intersection of the orbit of the satellite with the appropriate magnetic shell, irrespective of latitude and longitude.

(c) The geometric thickness of the shell was similar to that of pretest estimates.

(d) The observed intensity of trapped electrons was in order-of-magnitude agreement with pretest estimates.

(e) The temporal decay of trapped intensity resembled pretest estimates.34

Our paper concluded with an extended discussion of the thickness of the Argus shells, their positions in space, their angular distributions, trapped lifetimes, injection efficiencies, and the distribution of the electron turning points.

After the examination of data from Pioneer 3 (launched earlier on 6 December 1958), the two-belt structure of the intense radiation zone was fully understood. That discovery had been published in Nature in February.35 The figure in that paper clearly

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Argus results

Argus resultsOPENING SPACE RESEARCH

INNER ZONE {NATURAL]

В ARGUS SHELL

C OUTER ZONE (NATURAL)

FIGURE 13.7 Copy of a figure presented at the April 1959 Symposium on Argus results. The re­lationship between the Earth, inner radiation zone, Argus shells, and outer radiation zones is shown to approximate scale. (Courtesy of the University Archives, Papers of James A. Van Allen, Department of Special Collections, University of Iowa Libraries.)

showed the two-belt structure and was adapted for our Argus paper by adding the location of the Argus shell, as shown in Figure 13.7.36

As was mentioned earlier, following our original announcement of the discovery of the radiation belts in May 1958, some on both sides of the cold war thought that the radiation might be residue from nuclear weapons testing already conducted above the atmosphere. The Americans thought the Soviets might have been responsible for them, and the Soviets suspected the Americans. Although the earliest satellites were able to map the extent of the belts, they provided only crude information about the particle composition and were not capable of demonstrating persuasively that the radiation was not man-made. It was not until the data were received from Explorer IV that the more qualitative and quantitative information permitted us to discriminate unambiguously between residue from nuclear detonations and the naturally occurring radiation.

Van Allen attended the Cosmic Ray Conference arranged by the International Union of Pure and Applied Physics in Moscow in July 1959. Although the Argus results had been declassified and presented orally in the United States before then, there had still been no published results available for the Soviet scientists to study. So at least some of the attending Soviets still believed that the radiation belts might have been man-made and that the United States was trying to conceal that information from them.37

CHAPTER 13 • ARGUS AND EXPLORERS IV AND V

Everyone was edgy during those cold war years. A federal official, most likely an agent from the U. S. Central Intelligence Agency, visited Van Allen before his departure for that meeting, asking that he prepare a “trip report” upon his return covering 11 areas of interest. They wanted information on recent cosmic ray work, names of the institutions and individuals involved, individuals behaving secretively or evasively, copies of all materials distributed at the conference, and other subjects. It was only natural for Van Allen to assume that he would be similarly observed by Soviet agents during his stay in Moscow.

While at the Moscow conference, Van Allen outlined the Explorer IV and Argus findings essentially as he had presented them in his lecture at the U. S. National Academy’s symposium more than two months earlier. The Soviets were very interested in that information, and Academician Leonid Sedov gave him a spontaneous invitation to give a more detailed technical seminar at the USSR Academy of Sciences that evening. Van Allen was apprehensive about the invitation. It was not unknown in those days for visitors to the USSR to disappear. Van invited fellow U. S. conference attendees John A. Simpson of the University of Chicago and George W. Clark of MIT to accompany him, figuring that “if all three of us disappeared, someone would certainly investigate.”

At the Academy, Van Allen spoke, showed our slides, and engaged in lengthy discussions with his Soviet cosmic ray counterparts. It was only after their careful ex­amination of the Explorer IV and Pioneer 3 data that the Soviets were fully convinced that the natural radiation belts and the artificially generated shells were two markedly different phenomena.

The summer 1953 rockoon expedition

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.

Подпись: 24OPENING SPACE RESEARCH

The summer 1953 rockoon expedition

FIGURE 2.1 A25-year-old George Ludwig in 1953, not long after beginning workin the Cosmic Ray Laboratory. Here I am wiring and checking timing circuits for an upcoming rockoon expedition. I felt like a kid who had been turned loose in a toy store.

 

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

CHAPTER 2 • THE EARLY YEARS

The summer 1953 rockoon expedition

FIGURE 2.2 Equipment for the 1953 rockoon expedition, ready for shipment. The instru­mented nose cones are stacked on top of wooden frames containing the 18 tail fins. Meredith’s nine instruments are in the near-field, with the nose cones beside them, while Ellis’ nine instru­ments are to the rear. The electronic firing assemblies (on which I had been working in Figure 2.1) lie at the bases of the instruments. One empty Deacon rocket casing lies atop the firing gondola frames. (Courtesy of the Department of Physics and Astronomy Van Allen Collection, The University of Iowa, Iowa City, Iowa.)

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

CHAPTER 2 • THE EARLY YEARS

The summer 1953 rockoon expedition

FIGURE 2.4 A rockoon on its way aloft, shortly after release from the deck of the icebreaker USS Staten Island during the 1953 expedition. The balloon envelope is only partly full here, but its helium expanded to completely fill it as it climbed into the rarified air at rocket-firing altitude. The firing gondola can be seen directly below the rocket’s tail fins. (Courtesy of Leslie H. Meredith.)

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

28 OPENING SPACE RESEARCH

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

CHAPTER 2 • THE EARLY YEARS

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

OPENING SPACE RESEARCH

Подпись: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

CHAPTER 2 • THE EARLY YEARS 31

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.

The summer 1953 rockoon expedition Подпись: FIGURE 2.5 A plot of the GM counter counting rate as a function of time for a typical rockoon flight in the absence of the auroral soft radiation. This was from flight 23, made on 3 September 1953, at a geomagnetic latitude of 55.6 de-grees north. (Courtesy of Leslie H. Meredith.)

OPENING SPACE RESEARCH

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.

Подпись: FIGURE 2.6 Counting rate of the single GM counter as a function of time for SUI flight 13 on 28 July 1953, at a geomagnetic latitude of 74degrees north.This represents the first detection of the auroral soft radiation. (Courtesy of Leslie H. Meredith.)
The summer 1953 rockoon expedition

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

CHAPTER 2 • THE EARLY YEARS 33

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.

The Stewart Committee and the Vanguard decision

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

CHAPTER 7 • THE U. S. SATELLITE COMPETITION

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

The Stewart Committee and the Vanguard decision

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

OPENING SPACE RESEARCH

Подпись: 188of 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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Подпись:• 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

OPENING SPACE RESEARCH

Подпись: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.

Making the data intelligible

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

Подпись: OPENING SPACE RESEARCH FIGURE 11.4 The bank of equipment used at SUI to process the signals from a variety of balloon, rocket, rockoon, and satellite flights. This picture was taken in late 1958, after the facility had grown to handle the data from Explorer IV, as well as that from Explorers I and III.The racks, from left to right, contain the original two-track tape playback unit, the seven-track playback unit that was added in the spring of 1958, the multichannel strip-chart recorder, two banks containing receivers, filters, and FM discriminators, and, finally, the camera recording system used for displaying the data from the Explorer III onboard data recorder. The racks also contained a variety of power supplies and test equipment.

310

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,

Подпись: Copyright American Geophysical UnionПодпись: Special Publications Opening Space Research: Dreams, Technology, and Scientific Discovery Vol. 62FIGURE 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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Подпись: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

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Making the data intelligible

FIGURE 11.6 A sample of the data from the Explorer III onboard tape recorder, as produced by the film recorder in the data-processing equipment at Iowa. This portion of a continuous 70 mil­limeter filmstrip contains a one minute segment of the satellite recorder’s data. Since the satellite’s orbital period was about 116 minutes, the filmstrip for a data dump from a full orbit was about 116 times this length. This example is completely noise-free, a rare occurrence—most readouts contained varying amounts of noise superimposed on the traces. The occurrence of only a sin­gle transition of the instrument’s scaler during this one minute period indicates that the raw GM counter rate was very low at that time. The normal in-orbit cosmic ray counting rate produced a missing pulse about once every seven of these one second pulses, thus, this example was probably made during ground testing. The author was unable to locate any still-existing filmstrips of original Explorer III flight data.

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.

Public exposure

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.