Sputnik-3, its flight and  radio systems

Sven Grahn

The first launch of the 8A91 version of the R-7 rocket, with Object D mounted beneath a nose fairing, took place from Tyuratam in  Kazakhstan at 0701 UT on April 27, 1958. As the rocket ascended, longitudinal resonance vibrations (an effect called "pogo") in the strap-on boosters increased in intensity as the propellant tanks emptied broke up 88 seconds after launch. A backup rocket and satellite were available and launched successfully into orbit at 0700 UT on 15 May 1958. The 1327 kg satellite, called Sputnik 3, entered a 230 -1880 km orbit at an inclination of 65.2 degrees. Sputnik 3 separated from the spent core of its launch vehicle. The satellite was a comprehensively equipped space science laboratory. It decayed from orbit on 6 April 1960.

Overview of  radio systems

Sputnik 3 was the first Soviet satellite to carry a complete radio system for telemetry, tracking and command. Of course Sputnik-3 was intended to be the first Soviet satellite and was known as "Object-D". Several references give details about the systems carried by the spacecraft:

Non-discovery of van Allen belts? - the tape recorder story

I have heard Russian scientists describe that Korolev decided to launch the back-up satellite, which we now know as Sputnik 3, despite the fact that its telemetry tape recorder was suspected to be out of order.  Pre-launch test indicated that the tape recorder was not operating properly. The manager in charge of the telemetry system and recorder, Chief Designer Alexei F. Bogomolov of OKB MEI, did not want to be the one to hold  up this important launch. Bogomolov insisted that the indications were due to  electromagnetic interference from sources in the test area and that the recorder worked properly. Perhaps the pressure from the Kremlin to launch made Korolev accept Bogomolov's explanation despite skepticism from other engineers and launch the back-up Object D.  The Kremlin wanted the satellite to be launched in time for the italian general elections  on May 25-26, 1958. The idea was that such a display of the superiority of Communism would help the Italian Communist party. In fact, it did not - the Italian communists did not increase its 23% share of the electorate.

Since the apogee of Sputnik 3 was in the southern hemisphere and the Soviet Union only had tracking stations inside the country (see map derived from 1) the tape recorder was needed to gather detailed data on the radiation belts. The tape recorder indeed malfunctioned in orbit. In this way, Soviet scientists missed critical data needed to properly interpret the data that would have made them first in discovering discovering what is now called the van Allen belts (see more below)!

In (12) we can read:

"... Signals from the southern part of the orbit, where Sputnik III was passing through the inner radiation belt zone, still could not be received on the territory of the Soviet Union. The Soviet scientific vessel "Ob' " with a receiver on board was on its way to the Southern hemisphere, but it only arrived there and reported data first in September 1958. Also in September 1958 the Soviet Union shared its radio code with Australian researchers, who until that time were able to receive but not to interpret the signals from Soviet Sputniks (Hess, 1968 [13]). From September 1958 on, information from both the northern and southern parts of the orbit could be received and analyzed by Soviet researchers. But when Vernov described his preliminary results in July 1958 at the Moscow Assembly of the International Geophysical Year Committee, he only had the data from the northern part... "
The radio signals received in Australia must have been the HF beacon "Mayak" and it must have contained data that partly compensated for the loss of the tape recorder for the "Tral" telemetry system. Let me quote from (4):
"....Sputnik 3 passed over the Antarctic at an altitude of 1800 km where a larger flux intensity was observed than in the Northern Hemisphere....However, the ionization in the scintillation crystal amounted to 2 x 1010 eV/sec in the Antarctic area, indicating a rise in intensity of 40-fold...."
Let me also quote from van Allen (5):
"...On a purely observational basis the Sputnik 3 data represented discovery of the earth's outer radiation belt inasmuch as they were acquired before those of Explorer 4 and Pioneer 3. However, the interpretation of Vernov et al did not encompass the idea of geomagnetic trapping....."
In (5) there is also talk about a partial failure of the telemetry system on 17 June 1958. Van Allen discusses in detail who was "first" and gives a very balanced picture of the state of knowledge of trapped radiation belts in the 1957-58 time frame - recommended reading.

Bart Hendrickx wrote to me about these matters:

This is also described in (6). The designer of the experiment was Sergei Nikolayevich Vernov, a professor at Moscow State University. The experiment did detect high concentrations of electrons, but Vernov's interpretation was that the electrons came from the metal body of the satellite itself and had been released by collisions with high-energy cosmic particles. This misinterpretation was mainly caused  by the malfunctioning tape recorder, which meant that the scientists only got information about electron distribution in a very limited portion of the satellite's orbit (while it was over Soviet territory) and did not get the general picture later provided by Explorer-1. To give at least some credit to Vernov the Van Allen radiation belts were long referred to in Soviet literature as the "Van Allen-Vernov radiation belts".

The "Mayak" radio beacon - a backup system for radiation data

The figure below on the left  shows the telemetry format structure of the "Mayak" beacon on 20.005 MHz. The figure below right shows a time vs. frequency plot from the CoolEdit audio software  of a 2-second part of the "Mayak" beacon signal. The telemetry format is indeed 1.23 seconds long as given by Fulpius... .  and the  three telemetry words start roughly when they should, but not quite! Listen!   Clearly, the Mayak beacon was the source of the radiation data from the southern hemisphere mentioned mentioned in (12) and (5) and I read many years ago that the USSR shared the radio code with western scientists.

I started a quest to find this "radio code" and started by contacting the World Data Center for rockets and satellites at the Goddard Space Flight Center and this is what R. Parthasarathy, Emeritus Professor of Physics, University of Alaska wrote in an e-mail on 17 February 2006:

"... I was deeply into monitoring and analyzing the Sputnik-3 (=1958 Delta-2) in Fairbanks, Alaska, to obtain 1) the total electron content
by means of the signal's Faraday Rotation, and 2) the height of the F-region ionospheric irregularities that cause the signal strength to become jittery. They were published in the Proceedings of IRE (which later morphed into Proc. IEEE), Vol 47, p-78, 1959, and Vol 47, p-1660, 1959.

While looking at the high-speed chart paper, my eye caught the structure of the pulses. They were obviously Pulse Width Modulated, may be a data stream.  I alerted my Director at the Geophysical Institute, Dr. Christian T. Elvey, who contacted his friend/acquaintance Vernov in USSR and obtained the "code" that modulated the pulsewidth. The IGY hierarchy, operatives, and celebrities had a proclivity to hog the credit, but in this case it was strictly one-on-one rapport between Elvey and Vernov. I also recall that Vernov, et al., had also a paper on the radiation from Sputnik 3 in the Planet. and Space Sci,. 1959/1960?

Soon after, I moved on to other things, and left this radiation analysis to two graduate students, Ron DeWitt and Roy Basler. I recall they pursued it enough to publish a paper in JGR (?) some time in 1960/61 ?? [See 8]. To my memory, there was no other publication on the radiation telemetered by Sputnik 3 from any other American worker... "

In Basler's and deWitt's paper (8), which I obtained from the library of the Swedish Insitute of Space Physics in Kiruna, I finally found a reference to an article by Australian scientists Herz et al (9) where the telemetry code is revealed! In (9) we can read that the second and third pulses after the sync pulse carried information from the NaI scintillation counter (see sketch below). The information of the first pulse was unknown to Herz et al (see below). The anode current from the photomultiplier is integrated and triggers  a bistable circuit that switches Relay A every time the NaI crystal has been subjected to 2 x 109 eV. The seventh dynode current controls Relay C  in the same way every time the energy released in the NaI crystal is 18 x  109 eV.

The last dynode was connected to Relay B via a scaler. On 17 June 1958 (5) Relay B froze in a fixed position, so Channel 2 corresponded to the anode current and Channel 3 corresponded to the seventh dynode current. The various combinations of positions of relays A, B and C led to pulse lengths of 50 msec, 100 msec or 150 msec, i.e. "short", "medium", and "long". However, when relay B "froze", channel 2 pulses were either  long or short and channel 3 pulses were either short or medium length. Pulse lengths between these lengths occurred when the relays changed positions while a pulse was being transmitted.

The positions of the relays were sampled at the frame rate of 1.23 seconds. A change in the length of a pulse occurred when the number of realy switchings during the previous frame was odd. The pulse length does not change when the number of switchings are even - i.e. the relay returns to the original position (since it is a toggle switch). If the time between relay switchings is large compared to the frame length every relay switching leads to a change in pulse length. In (9) it is explained the "common sense suggests that the converse is also true: that changes in pulse-length at intervals large compared with the cycle length denote an equal number of switchings, each of which occurred during the cycle immediately preceding the change". In (9) there is also a graph that shows that the switching rate is not an unambiguous function of the interval between pulse length changes when the switching interval is less than the frame length. The pulse change interval varies very fast with changes in relay switching  rate (for switching intervals less than the frame length). If, in such a situation, the switch rate fluctuates, the probability of long pulse-change intervals is low. Herz (9) also concluded that for switching intervals longer than the frame length the pulse-change interval is identical to the switching rate for the relay in question. Most of the time Herz (9) noted that the less sensitive channel 3 operated in this regime. For channel 2 the interval between pulse length changes  rarely exceeded two frame lengths and it is was evident that the switching rate was less than the frame length. Therefore it was impossible to obtain directly an unambiguous value for the switching rate without additional information - in this case the difference in sensitivity between channels 2 and 3. In this way Herz et al were able to deduce the switching rate of both relays A and C.

It is interesting to note that the School of Physics at the University of Sydney received a request from the USSR Academy of Sciences in June 1958 to record signals from Sputnik 3. They recorded signals on 20.005 MHz eight times between July 19 and  August 4 1958. In September 19585 they received the details of the detection system to be able to decode the telemetry. The conclusion in their paper is that they, in the recordings made in Sidney, is that they could detect the gap between the inner and outer radiation belts. It seems that Vernov and his colleague were trying desperately to obtain data from the southern hemisphere by using the Mayak beacon when the tape recorder for the Tral telemetry system was out of order.

But what was the first pulse? I have in my files an article (16) by a Swiss gentleman named A. Fulpius, but the photo-copy has no mark as to the publication's name or date of issue. I think it is either Interavia or an ITU publication. In this article there is a little sketch of the Sputnik-3 signals as that above but it shows that pulse 1 (called word 1 on the figure above) only can take on short or long values, while the other two can take on all three values. In the caption of the little sketch we can read - in French: "La première impulsion indique l'alimentation, soit en batteries chimiques, soit par cellules solaires". ("The first pulse indicates the power supply, either chemical batteries or solar cells").

It is interesting to note that Herz et al (9) also (just as I noted from the short signal sample above) found that the telemetry system did not perform exactly as specified. The pulse lengths and the frame length varied from time to time. This information is shown in the little table on the right.

In Vernov et al (15) there are many details about the instrumentation on Sputnik-3. The integrator and triggering mechanism for the relays described above turns out to be a capacitor that is charged by the photomultiplier current. A neon lamp across the capacitor ignites at a certain voltage and the voltage drops down to the extinction voltage of the lamp. In (15) we can also learn that the diesel-electric ship "Ob" received Sputnik-3 signals on 20 MHz while it was near South America. Interestingly Vernov's and Chudakov's paper contains a graph of radiation data with a latitude/longitude scale along the abscissa. This information can be used to draw the ground tracks for these two passes near the ship "Ob". From the graph shown here (dotted lines are radio horizons) it seems that "Ob" was near the southern tip of South America.

According to (4) there was radio contact with Sputnik-3 until its decay after 691 days. This is verified by A Fulpius, a radio amateur in Geneva (16).


  1. Yuri Mozzhorin in  "ROADS TO SPACE, An oral history of the Soviet Space Program", edited by John Rhea, translated by Peter Berlin and published by the Aviation Week group in 1995.
  2. TASS communique, 16 May 1958, "On the Launching of the Third Soviet Artificial Earth Satellite".
  3. "Scientific Satellites", NASA SP-133, by William Corliss
  4. Wukelic, G.E. (ed), "Handbook of Soviet Space-Science Research", Gordin & Breach, New York, 1968, Library of Congress Catalog Card Number: 67-30479, pp 244-245.
  5. Van Allen, James, "Origins of Magnetospheric Physics", Smithsonian Institution Press, Washington, DC, 1983.
  6. Chertok, Boris, "Rakety i Lyudi" vol 2, pp. 208-209.
  7. New revelations of frequencies for early Soviet spacecraft
  8. Basler, R. P.; Dewitt, R. N.; Reid, G. C.  Radiation Information from 1958delta2, Journal of Geophysical Research, Vol. 65, p.1135, 1960
  9. Herz, A.J., K.W. Ogilvie, J. Olley, and R.B. White, Radiation measurements with satellite 1958-delta-2 over Australia, Nature, 184, 391, 1959.
  10. Kellog W.W. IGY rockets and satellites: A report on Moscow meeting, August, 1958 // Planet, and Space Sci. 1959. Vol. 1, N 1. p. 71
  11. Annals of the International Geophysical Year, Volume V, Parts IV, V & VI, 1958, IGY Instruction Manual, London, Pergamon Press, 1958
  12. Zavidonov I.V., Sputniks, Explorers and Propaganda: the Discovery of the Earth's Radiation Belts // History and Technology, 2000, Vol. 17, pp. 99-124
  13. Hess Wilmot, N., 1968. The radiation belt and magnetosphere, Waltham Mass.: Blaisdell Pub. Co.
  14. DOSAAF (Dobrovol'noe obshchestvo sodeistviia armii, aviatsii i flotu)  Voluntary Society for Assistance to the Army, Air Force, and Navy. Responsible for premilitary training of Soviet youth.
  15. Vernov, S.N., Chudakov, A.E., "Terrestrial Corpuscular Radiation and Cosmic rays", Space Research 1, 1960, pp. 751...
  16. Fulpius, A (geneva) "Un radio-amateur à lécoute des satellites artificiels", Unknown publication or date!


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