The secretiveness of the Soviets caused them to miss discovering the Earth’s radiation belts. There have been recurring debates about bragging rights to the basic discovery and to the finding that there were two distinct regions of trapped radiation.54 55
Sputnik 1 carried no scientific instruments (other than those for internal temperature and pressure engineering measurements), and so, of course, had no way to detect the trapped radiation. On the other hand, Sputnik 2, launched on 3 November
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1957 (well ahead of Explorers I and III), did carry two GM counters that no doubt responded to the intense radiation. That satellite’s orbit, with an apogee height of 1131 miles and orbital inclination of 65.3 degrees, was admirably suited for detecting and studying the radiation.
But the Soviets did not receive data from regions where the higher readings would have been seen. Their data-receiving stations were located within the northern hemisphere, mostly within the Soviet Union, where the satellite was at its lowest height— generally below the trapped radiation.56 To compound the situation, the Soviets did not make information available that would have enabled scientists outside the Soviet Union to work with the satellite data.
The Soviets did obtain a single reading of a mildly increased intensity from Sputnik 2. A station in the northern USSR, on 7 November 1957, showed an increased radiation intensity, by about 50 percent. The indication was similar in general character to the measurements of the auroral soft radiation seen by the Iowa group during their 1953, 1954, 1955, and 1957 rockoon expeditions. Those auroral zone high-intensity readings were centered at about 68 degrees geomagnetic latitude, as shown in Figure 2.14, and at altitudes above about 50 miles. The Sputnik 2 anomaly was seen at a geomagnetic latitude of about 55 degrees over the Soviet Union, at a height of about 188 miles.
It was recognized during 1955-1957 that particles producing the soft auroral readings were being at least funneled into the polar regions by the Earth’s magnetic field. In fact, some of the enhanced radiation may have been from electrons captured in durable trajectories in the Earth’s magnetic field. Therefore, it is possible that the soft auroral radiation may have been the first weak manifestation of the presence of the outer radiation belt. We certainly did not arrive at that conclusion at the time, and never took the position that the detection of the soft auroral radiation represented the discovery of the Earth’s trapped radiation.
The single anomalous Sputnik 2 reading later served as the basis for the frequent claim by the Soviets that they discovered the outer radiation belt.
The first known report of that reading was by Academician A. V Topchiyev, chief scientific secretary of the Soviet Academy of Sciences, who reported at its annual meeting beginning on 25 March 1958:
Observations of cosmic rays by the satellite gave evidence of the variations of the intensity of its radiation. These variations evidently are connected with the condition of the interplanetary medium near the Earth. One case of a sharp rise to 50% of the number of particles of cosmic radiation was observed. Excellent agreement of readings of both instruments exclude the possibility of explaining this case as due to errors in the apparatus. At the same time, cosmic ray ground stations did not detect a substantial increase in cosmic ray intensity at this time.
At present, a detailed study of this occurrence is being made. It is possible that they are caused by a new phenomena [ліс], namely, by generation of cosmic rays of very low energy on the Sun which are strongly absorbed by the Earth’s atmosphere.57
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A full-page article in the 27 April 1958 issue of Pravda presented a compilation of results of the experiments conducted by Sputniks 1 and 2. It included a brief mention of the 50 percent increase in intensity mentioned above. The new article repeated the earlier assertion that it may have been a burst of radiation from the Sun.58
Our public announcement of the discovery of the high-intensity radiation was made on 1 May 1958. The paper on which the lecture was based, as well as the lecture itself, clearly attributed the high-intensity radiation to particles trapped in the Earth’s magnetic field. It was later universally agreed that Explorers I and III had observed the lower fringe of the inner radiation belt, with satellite orbital inclinations too low to see the outer cusps of the outer radiation belt.
The story of Sputnik 3 must have been especially galling to the Soviet scientists. That was the satellite that they first designed as their ultimate contribution to the IGY. Being very large and complex, its development required a tremendous effort. The Soviet support institutions and officials were slow at first in rising to the design task, and its schedule slipped month by month. It finally lagged so much that the Soviet hierarchy began to fear that the United States would beat them into space.
As early as January 1957, Sergei P. Korolev, the leader of the Soviet Intercontinental Ballistic Missile (ICBM) rocket program, suggested the development of two satellite versions: the full one envisioned by the scientists and a simpler one that came to be known internally as the Simple Satellite. In August 1957, after the R-7 ICBM successfully propelled a dummy H-bomb warhead over 3500 miles to Kamchatka, Korolev argued to the State Commission for the ICBM, and then to the Presidium of the Central Committee of the Communist Party, for the quick launch of the simpler polished sphere. With their nervous acquiescence, he pushed the preparation of that satellite forward in time for the 4 October launch.
The launch of their more complete IGY satellite was delayed still further following the resounding success of Sputnik 1. Soviet Premier Nikita Khrushchev finally realized what a politically hot property he had and instructed Korolev to launch something new in space in time for the next anniversary of their revolution. That goal could not be met with their primary satellite. By setting aside all normal procedures for designing and producing a new object, his team was able to prepare Sputnik 2 with portions of the leftover Sputnik 1 hardware, and with its dog as added cargo, in less than a month. It was launched on 3 November 1957.
After that, things started coming together for the launch of the much-anticipated larger scientific satellite. The first attempt on 27 April 1958, however, failed. The rocket engine quit at about eight miles’ height, and the satellite separated from its launcher and tumbled to the ground.59
A second launch attempt finally placed Sputnik 3 in orbit on 15 May 1958. But there was another problem. During the prelaunch checkout, the onboard tape recorder
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did not appear to be working properly. Two stories exist about the decision to proceed with the launch in spite of that difficulty. The first is that the recorder’s chief designer, Alexei Bogomolov, supremely confident of his creation, suggested that the testing failure was caused by electromagnetic interference from the many radiation sources in the test room and recommended that the countdown continue.60 The second version is that the order to launch came to Korolev directly from Premier Khrushchev, who wanted the satellite launched before the Italian general elections on 25-26 May, in the belief that that display of the superiority of Communism might help the Italian Communist Party in that election.61 It is possible that both factors played a role. In any event, the launch took place, and it was found that the tape recorder had, indeed, failed, thereby denying them access to data from other than the regions surrounding their ground receiving stations.
Sputnik 3 carried a very impressive array of scientific instruments, including detectors that were easily capable of showing the presence of the high-intensity radiation. As in the case of Sputnik 2, however, the array of Soviet ground receiving stations did not include significant coverage outside the Soviet Union. The failed onboard tape recorder did not provide data from the regions where most of the indications of the high-intensity radiation would have been seen. Those shortcomings would have been somewhat ameliorated if the Soviets had made the technical information needed to decode the satellite data available to the outside world. But their obsession with making their satellites appear to the world as unaided triumphs of Soviet Communism made it impossible for outside radio amateurs and eager IGY colleagues to provide additional data.
The 15 May launch of Sputnik 3 was followed by a series of reports of satellite performance in the press and scientific literature. For example, Pravda, on 18 May 1958, carried a full two-page article on Sputnik 3. That article, however, was limited to a general description of the program, of the instruments, and of the planned scientific program and included no mention of scientific results.62
A new Soviet reference to anomalous radiation was finally published in Tass in mid-July. It continued to ignore the U. S. announcement in May of the trapped radiation discovery. That Soviet announcement read:
Thanks to the instruments installed in Sputnik III a new phenomenon in science was discovered, a special type of corpuscular radiation which up to now had not been observed in the
composition of cosmic rays. Specialists are now engaged in puzzling out this phenomenon.63
The written papers provided by the Soviets for the Symposium on Rockets and Satellites at the Fifth Meeting of the Comite Speciale de l’Annee Geophysique Internationale, Moscow, on 30 July to 9 August 1958, made no mention of particle trapping. But Sergei N. Vernov, during a specially arranged evening address, discussed the Sputnik 2 and 3 results beyond the written papers. The best account of
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Soviet information actually presented at the symposium is contained in the summary prepared by William Kellogg soon after the symposium. He reported that Vernov’s evening discussion, as it related to charged particle results, dealt primarily with the traditional cosmic rays.64
According to Kellogg, in that evening lecture, Vernov described the anomalous readings as observations of the “electron component of the cosmic rays” and made no mention of particle trapping. Specifically, he reported that Sputnik 3 had seen variable but high intensities of radiation that often exceeded the dynamic ranges of their detectors over the Soviet Union (in the latitude range from 55 degrees to 60 degrees north). He suggested that the increased flux was likely due to bremsstrahlung radiation from electrons interacting in the material of the satellite and detector and outlined two possibilities for their source. The first was that the electrons might be accelerated near the Earth by electric fields like those assumed to exist in aurorae. His second suggestion was that the electrons might originate away from the Earth, possibly on the Sun, and that they penetrated through the Earth’s magnetic field because of irregularities in that field. Van Allen later reported “that [Ernest] Ray had attended the Fifth General Assembly of the IGY from July 30-August 9, 1958, and heard papers by Vernov and Alexander Chudakov, the first exchange of Russian and American scientists regarding the radiation belts. They offered no report on the outer belt and no graphic rendering of the belts as shown in Van Allen’s reports.”65
The information presented by Vernov at the symposium was modified and considerably expanded in a paper by him and his colleagues that was later widely published. That paper, appearing well after the Moscow Symposium, contained the first known Soviet mention of charged particle trapping in the Earth’s magnetic field, stating:
Apparently, two types of variations occur. One type of the variation is caused by cosmic rays, and it must therefore respond to changes in the number of primary cosmic rays. The other type of variation does not concern cosmic rays. Apparently, a new type of radiation, and a variation of the intensity of charged particles and photons caused by this radiation were recorded on the satellites with the help of the apparatus constructed for the study of cosmic rays. This variation is caused by the radiation which can be called “earth radiation,” i. e., the particles of high energy originating near the earth and rotating around the earth.
A. I. Lebedinskiy and one of us (S. N. Vernov) considered the possibility of storing a large number of secondary particles near the earth. These particles are able to move quasiperiodically from one hemisphere to another. In the first approximation, the motion of the particle in the magnetic field must take place in such a way that the magnetic moment of the particle will be constant. Therefore, a charged particle is “trapped” in the region of a relatively weak magnetic field. These particles are able to perform a large number of oscillations and their intensity must be very large. One source of particles is the decay products of neutrons emitted by the earth under the action of cosmic rays. On the other hand, it is possible that particles from corpuscular streams emitted by the sun may also be such a source.66
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Thus, the situation at the end of the Moscow Symposium in early August 1958 was that the U. S. results from Explorer IV substantiated the earlier discovery of trapped radiation by Explorers I and III. The data were, however, still too sparse to infer the existence of two separate radiation zones. The Soviets were still very tentative in their explanation of the anomalous readings that they had received from Sputniks 2 and 3, had not yet attributed them to particle trapping, and had not postulated two separate regions of radiation. That latter conclusion awaited southern hemisphere data from Sputnik 3 and data from the U. S. Explorer IV satellite launched on 26 June 1958 and from the Pioneer 3 space probe launched on 6 December 1958.
Van Allen much later summarized the situation: “In retrospect, I should say that both the Soviets and we independently did have the basis—as of late August—for speculating on the structure of the [outer] radiation zone. But neither group had the perspicacity to do so at the time.”67,68
There is little doubt that, if the Soviets had openly included the world’s scientists and others in their endeavor, useful Sputnik 2 data would have been available from lower latitudes and higher altitudes—most importantly over South America and the South Atlantic Ocean. With that, the new phenomenon might well have become known as the Vernov Radiation Belts instead of the Van Allen Radiation Belts. Even without those data, if the recorder on Sputnik 3 had worked, the outer belt could have become known as the Vernov Outer Radiation Belt.69
Being solar powered, Sputnik 3 provided scientific data for about a year. In the fall of 1958, some data from south of the equator began to become available to the Soviet scientists. The Soviet research vessel Ob reached the southern hemisphere and began providing data in September. Also in September, the Soviets shared their radio code with Australian researchers, who began providing data from the region where the satellite was near its greatest height, and therefore, ideally sited to provide valuable data on the radiation belts.
The point at which it can be claimed that the outer belt was discovered remains a question of interpretation.