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This still from a film made post-Sputnik, gives a good sense of the size of the actual satellite. (credit: Don Mitchell)

Sputnik remembered: The first race to space (part 1)

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On the early morning of September 20, 1956—just before 2 am—the US Army launched a Jupiter C intermediate range ballistic missile from Launch Pad 5 at Cape Canaveral. Basically a souped-up version of Wernher von Braun’s Redstone rocket, it had a dummy fourth stage loaded with sand. The missile lifted off successfully, generating a thrust of over 35 tons from its first stage engines, which burned for 150 seconds. The upper stages continued to arc over the Atlantic, reaching an altitude never reached before by any human-made object: nearly 1,100 kilometers. The payload itself traveled downrange about 5,400 kilometers from the launch site before burning up in the Earth’s atmosphere. As radio systems beamed back information to the blockhouse on the record-breaking flight, von Braun was said to have “danced with joy.”1 Although the Army did not publicly announce the launch or the results of the flight, information about the event leaked out to the mainstream press within a week.2 This somewhat obscure missile launch may have irrevocably changed the course of the “space race,” serving as one of the main catalysts for the world’s first artificial satellite, Sputnik.

By the time of the Jupiter C launch, Soviet scientists and engineers had been engaged in research and development on satellites for quite some time.

For being one of the most cataclysmic events of the Space Age, there are relatively few accounts of the actual launch of Sputnik. When we remember it, we usually focus on the aftermath: the shock of the satellite, especially in the United States. For good reason, there has been much rumination, both academic and popular, on its meaning, impact, and long-term reverberations. But the story of its genesis and the event itself remains murky and full of speculation, lacking detail. We have some specific technical details filled in—the type of rocket used, the time of the launch, and so on—but the larger story, besides some scattered anecdotal accounts, is fragmented. The goal here in this piece is to focus on the actual events of 1957: how was Sputnik designed? How was it built? What happened during the launch? Who publicized it? Who tracked it? The goal here is to revisit, with the benefit of many new declassified documents from Russian archives, the “opening shot” of the Space Age.

By the time of the Jupiter C launch, Soviet scientists and engineers had been engaged in research and development on satellites for quite some time. Satellite studies in the Soviet Union had begun in the early 1950s under the tutelage of famous Soviet rocket designer Mikhail Tikhonravov (1900–74) at a secret military organization known as the Scientific-Research Institute No. 4 (NII-4 or “nee-4”) based in the northeastern Moscow suburb of Bolshevo.3 Tikhonravov had already enough achievements under his belt to guarantee a place in the annals of Soviet space history. In 1933, a rocket he designed, the “09,” became the very first Soviet rocket to fly using liquid propellants. Later, at NII-4, he had led early design studies on clustered staging concepts that ended up being used (in much modified form) in the famous R-7 intercontinental ballistic missile. More than 60 years after he proposed the clustering concept, the R-7 continues to be used today, albeit in significantly uprated versions.

The R-7 was designed at the famous Experimental Design Bureau No. 1 (OKB-1) based in the Moscow suburb formerly known as Kaliningrad under the leadership of legendary Chief Designer Sergey Korolev (1906–66). Much has been written about Korolev’s life:his apprenticeship in the 1930s as a young amateur rocket enthusiast, his arrest and incarceration in the Stalinist Gulag, and his meteoric postwar rise as one of the geniuses behind the Soviet missile and space programs. Yet, Korolev’s early successes might not have been possible without the help of Tikhonravov. Korolev had known Tikhonravov since the late 1920s, when they both participated in amateur glider competitions, and it was under Korolev’s overall direction that Tikhonravov had designed the famous 09 rocket. In the mid-1950s, OKB-1’s primary goal was to develop increasingly powerful ballistic missiles capable of delivering nuclear warheads to strategic targets. Although they worked in different organizations, Korolev remained close to Tikhonravov and followed the latter’s satellite work with keen interest.

The possibility of actually launching a satellite remained more or less a fantasy until the advent of the ICBM, which theoretically could impart sufficient velocity to a small object for it to enter a freefall trajectory around the Earth. In May 1954, soon after the Soviet government formally approved development of the R-7 ICBM, Korolev began lobbying senior industrial leaders to sanction a satellite project. He depended to a great degree on the “Tikhonravov Group,” a group of young scholars at NII-4 who, since September 1953, had been busily working on a concrete proposal for an artificial satellite of the Earth. Korolev’s projects were given an imprimatur of legitimacy by the involvement of Academician Mstislav Keldysh (1911–78), a brilliant applied mathematician who specialized in a wide variety of phenomenon, including aerodynamics, hydrodynamics, and vibration theory. Keldysh was an extremely influential and highly respected scientist, particularly within the secret world of weapons development. These three men—Korolev, Keldysh, and Tikhonravov—formed a very effective lobby group that pushed the idea of a satellite to the Soviet Party and government leadership. The story of how they did this is stranger than one can imagine.

This much-reproduced photo of Sergei Korolev was taken in 1953 when he was at the Kapustin Iar launch site directing launches of the R-5 strategic missile. (credit: Asif Siddiqi)

One of the strategies that Korolev used to get support from the top was to flood the Soviet media with speculative articles about the future of space travel. One of these articles, a lengthy one, was published in the Soviet newspaper Vecherniaia moskva (Evening Moscow) on April 16, 1955. Among other things, it announced the formation of a Soviet commission to study interplanetary space, a commission that we now know was really nothing much but a front for Soviet scientists to write articles in the media on the topic of space exploration. Although the commission had no authority to develop a satellite (let alone a rocket to launch it), the announcement of its existence caused a flurry of attention in the American media, probably just as Korolev and Tikhonravov had intended. The New York Times and Washington Post wrote about it. Even the CIA took notice: in their next top-secret National Intelligence Estimate, there was talk of this article. All of this was taken as evidence that the Soviets were racing to launch a satellite. In fact, there was no such plan at the time. But the anxiety about a Soviet launch was one (although not the only or most important) factor that played into the decision of the Eisenhower Administration, announced with much fanfare on July 29, 1955, that a launch of an American satellite was planned for the so-called International Geophysical Year, in 1957–58.

Although the mission of the Jupiter C launch in September had nothing to do with a satellite launch, by the time news of the flight reached Korolev, it was reported as an “attempted launch of a satellite.” This clearly garbled piece of information shook both Korolev and Tikhonravov.

The American announcement was reported back to Korolev. And almost immediately he wrote a letter (co-authored with some high-ranking Soviet industrial bureaucrats) to Nikita Khrushchev and Nikolai Bulganin, arguing that the Soviet Union needed to respond. To add power to his request, he added a folder containing a bunch of recent articles from the American media, all properly translated, all communicating that the United States was giving priority to its own satellite program. The attached folder clinched the deal: a little over a week after the American announcement, on August 8, 1955, the Soviet Politburo approved a satellite project under Korolev. A later government decision, from January 30, 1956. formally approved a firm program to launch what was known as “Object D,” a massive 1.3-ton scientific observatory that would beat the Americans.4

Anxiety about Americans

Building the complicated Object D satellite on time proved to be very challenging, especially since many of the scientific instruments had to be redesigned for Earth orbit, i.e., in conditions of near vacuum, weightlessness, and unknown radiation. In addition, ground tests showed that the launch vehicle slated to launch the Object D, known as the “article 8A91” (basically an R-7 ICBM with some improvements), would not have the necessary specific impulse required to launch the heavy satellite into orbit.

In this context, in late 1956, news of the American Jupiter C test provoked the Soviets in an inexorably different direction. Although the mission of the Jupiter C launch in September had nothing to do with a satellite launch, by the time news of the flight reached Korolev, it was reported as an “attempted launch of a satellite.” This clearly garbled piece of information shook both Korolev and Tikhonravov. There were all the troubles with the Object D to contend with, and now this supposed American “space” launch. If they were concerned about losing first place to the Americans, they were now seriously anxious. Korolev had long complained about all the delays with the Object D to Tikhonravov; usually Tikhonravov remained quiet, pondering over all the problems. Korolev had often seen this as indifference on Tikhonravov’s part but in fact, the latter had been devising an alternate plan, a “Plan B.”

In mid-November 1956, Tikhonravov suddenly piped up to Korolev: “What if we make the satellite a little lighter and a little simpler? Thirty kilograms or so, even lighter?”5 Korolev quickly pondered over the suggestion, weighing all the options carefully. One of the main problems with the development of the Object D had been the many delays in delivering its component scientific instruments. Having never designed instruments to operate in space, the subcontractors were facing many problems during production and testing. Instead of the complex Object D, Tikhonravov suggested reducing the satellite down to its most essential components: one or two radio transmitters and a power source to feed them. Finding this plan more and more attractive, Korolev decided to cut out almost all of the subcontractors and rely instead on two people he could count upon. He asked fellow Chief Designer Mikhail Riazanskii (1909–87) of NII-885 to provide the radio equipment and Chief Designer Nikolai Lidorenko (1916–2009) of the Scientific-Research Institute of Current Sources (NII IT) to supply the batteries to power the former. Everything else would be built in-house under his direct command at OKB-1’s experimental plant located right next to the design bureau premises. True to its elementary nature, the new satellite was called PS-1 (Prosteishyi sputnik-1, Simplest Satellite-1). It was so simple, the idea went, that it could be built and tested in a month or two, time enough to beat the Americans to the launch pad. The satellite would not only be simple but also cheap—if it was destroyed on launch, they could quickly ready another one without much ado.

Not everyone supported the PS-1 plan. In fact, although Korolev and Tikhonravov firmly believed in the idea, the third man in the original satellite proposal, Academician Keldysh, strongly opposed it. Keldysh had good reason to do so: he was, after all, the scientific head of the original Object D project. He had also committed the resources of the Academy of Sciences into the massive scientific observatory and didn’t want to have to tell his scientists that their beloved satellite would not be the first. Others in Korolev’s design bureau also opposed the new plan. For example, Il’ia Lavrov (1920–1995), one of Korolev’s engineers who had invested an enormous amount of energy into bringing the Object D satellite project to fruition vocally objected. Speaking of the “simplest satellite,” he told his colleagues that “this sphere is nonsense and a disgrace to the design bureau,” and that they should finish the original job that they set out to do on the Object D.6

Top leaders in the Soviet government were convinced, and about a month later, on February 15, the government issued a formal decree approving work on the new plan. Two identical satellites, PS-1 and PS-2, would be launched in April and May 1957 on retooled R-7 rockets.

More than internal dissension, Korolev also needed to convince the government that this was the right thing to do. He knew the military would be problematic. They had already committed to handing over a military weapon, the R-7 ICBM, to launch the “useless” Object D satellite. Now, Korolev wanted more ICBMs to launch another satellite. On January 5, 1957, he sent a letter to the government with his revised plan, asking for permission to launch two “simplest satellites,” each weighing about 40–50 kilograms, between April and June 1957, i.e., before the beginning of the International Geophysical Year (IGY).7 As is well-known, the IGY was sponsored by the International Council of Scientific Unions as a planned period of 18 months (July 1, 1957, to December 31, 1958), during which scientists from all over the world would carry out an intense program of research on geophysical phenomena. Korolev’s thinking on scheduling the satellites was based on the premise that since the Americans were planning to launch a satellite during IGY, if the Soviets managed to launch before the IGY, they would probably come out ahead. Knowing that government leaders would respond more strongly to competition with Americans than any rationale of scientific research, Korolev, in his letter, prominently highlighted the possibility that the Americans might easily preempt the Soviets. In other words, this was an urgent situation. Perhaps the most important bit of text Korolev’s somewhat disingenuous appeal was that, far from deleteriously affecting the ICBM test program, a satellite launch would actually help “solve a number of questions [related to] the launch, work of the engines, stage separation, etc.).”8

Top leaders in the Soviet government were convinced, and about a month later, on February 15, the government issued a formal decree approving work on the new plan. Two identical satellites, PS-1 and PS-2, would be launched in April and May 1957 on retooled R-7 rockets.9 Their orbits would range in altitude from 225 to 500 kilometers. According to the Politburo decision, the goals of the PS satellites would be rather simple: “prepare two R-7 [rockets] with an artificial Earth satellite and [associated] ground equipment for their launch in May or June 1957.” These launches would be carried out only if “favorable results” were produced of “one or two R-7” rockets launched in the test series. While the Academy of Sciences was given permission to generally publicize the idea of satellites, there was to be no “disclosure of any information about the [launch vehicle] of the satellite.”10

A cone or a ball?

Looking at the shape of Sputnik now, it seems obvious that the world’s first artificial satellite should have had such an elegant design. In the beginning, however, designers were not sure of its form. Long before official approval of the PS-1 plan, on November 25, 1956, Korolev had tasked a young antenna specialist in his design bureau, Nikolai Kutyrkin, to make the initial drawings for the satellite.11 Early on, the designers working on the satellite settled on a cone-shape for PS-1, echoing the cone chassis for the much larger Object D. They reasoned that a cone would fit well and naturally with the shape of the R-7 rocket’s payload fairing.

But when Tikhonravov’s deputy Evgenii Riazanov met with Korolev to show him some draft sketches of the satellite, Korolev flipped through all of them and didn’t like any. Cautiously, Riazanov asked “Why?” to which Korolev mysteriously answered, “Because it’s not round.”12 And as one designer later remembered, “there were weighty scientific considerations” in favor of a sphere.13 Two factors were crucial for picking a sphere. First, a sphere was an ideal geometric shape with maximum volume in ratio to minimum surface area, giving it a favorable tradeoff between packing as much equipment into as possible vs. limiting surface area exposure to changes in temperature. Second, a spherical shape (as opposed to more irregularly shaped objects) was ideal for determining atmospheric density on its orbital path. Korolev also apparently believed that a shiny metal spherical object would better reflect light and thus have a better chance of visibility with telescopes. It was, however, clear that such a small object would not be visible to the naked eye. Visually tracking a moving object at about 1,700 kilometer range (the distance of the satellite from an observer as the satellite was above the horizon) was practically impossible.

The designer of Sputnik was Mikhail Tikhonravov, shown here in c. 1970. His career spanned over four decades during which he contributed to some of the greatest achievements of the Soviet rocket and space programs. (credit: Asif Siddiqi)

The technical stuff: Sputnik inside out

It’s worth remembering here the exact design and construction of Sputnik, if only to admire the creativity of its designers as well as the way the urgency of its construction often affected its design. At its core, there were six major guidelines followed in the construction of the satellite.14 According to Tikhonravov, Sputnik’s primary designer, they included the following:

  • The satellite would have to be of “maximum simplicity” and reliability while keeping in mind that methods used for this satellite would be used in future projects;
  • The body of the satellite would be spherical in order to determine atmospheric density along its orbital trajectory;
  • The satellite would be equipped with radio equipment working on at least two different wavelengths, with sufficient power to be tracked by amateurs as well as to obtain data on the propagation of radio waves through the ionosphere;
  • The antennae would be designed so as not to affect the intensity of the radio signals if the satellite were to spin;
  • The power sources would be onboard chemical batteries ensuring work for two to three weeks; and
  • The attachment of the satellite to the core stage would be designed in such a way as to minimize the possibility of a failure in separation, or a failure in the deployment of antennae.

According to Tikhonravov, there were five primary scientific objectives of Sputnik:

  • To test the method of placing an artificial satellite into Earth orbit and to verify its separation from the launch vehicle;
  • To provide information on the density of the atmosphere that would be useful for calculating the orbital lifetime of future satellites;
  • To test radio and optical methods of orbital tracking;
  • To determine the effects of radio wave propagation through the ionosphere; and
  • To check principles of pressurization used on the satellite.

Initial conceptions of the satellite had the sphere as being quite small, weighing in at about 50 kilograms, with a diameter of 500 millimeters.15 At some point in early 1957, the satellite’s design mass doubled to about 80 kilograms (although the mass margin was about 100 kilograms.) The satellite, as it eventually took shape, was a pressurized sphere, 58 centimeters in diameter made of an aluminum alloy 2 millimeters thick (a particular kind known as “AMG6T” in Russia.) The sphere was constructed by combining two hemispherical casings (“front” and “rear” half-casings) together along a ring-like rubber seal. The overall pressurized sphere was held together by 36 bolts. The front half-casing was smaller than the rear half-casing, although it was covered by a one-millimeter thermal shield. It also had four fittings with support projections for inserting the long external antennae.

The pressurized internal volume of the sphere was filled with nitrogen (at 1.3 atmospheres) which maintained the following:

  • An electro-chemical source of power (three silver-zinc batteries);
  • Two D-200 type radio-transmitters;
  • A DTK-34 type thermal regulation system;
  • A ventilation (fan) system to regulate the temperature of the satellite;
  • A commutator;
  • Temperature and pressure sensors; and
  • Associated wiring.

The power source unit was shaped like an octagonal prism (450 by 270 millimeters) attached to the “front” half-casing. The unit had a cavity into which the radio equipment was “embedded.” An octagonal shape was chosen both to ensure symmetrical circulation of the nitrogen gas inside the pressurized sphere and to efficiently remove heat produced by the radio transmitters. Of the three batteries (each shaped like a rectangular block), two provided power to the radio equipment while the third supplied power to both the ventilation fan, which regulated the temperature within the satellite, and to the commutator. By means of a switch operated by a temperature sensor (a thermocouple), the fan was designed to operate when temperatures were higher than 30°C and turn off when values were between 20 and 23°C.

The two D-200 type radio transmitters operated on frequencies of 20.005 and 40.003 megacycles at wavelengths of 15 and 7.5 meters. These transmitters (which obviously used vacuum tubes) each had a power intake of one watt and provided the famous “beep-beep-beep” sound to Sputnik. The signals on both the frequencies were spurts lasting 0.2 to 0.6 seconds, and carried information on the pressure and temperature inside the satellite; one set would transmit during the “pauses” of the other. The frequency of the signal, as well as the relationship between the length of the signals and the pauses in between, would change according to changes in temperature and pressure within the satellite hull. The satellite had simple pressure and temperature pickups that would close a circuit, given certain ranges of temperatures (greater than 50°C or less than 0°C) and pressures (less than 0.35 atmospheres), thus changing the signals’ parameters.16 The radio equipment package unit, shaped roughly like a rectangular block (100 by 130 by 390 millimeters), was hooked to a joint on the “front” half-casing and cushioned by a shock absorber.

The satellite, as it eventually took shape, was a pressurized sphere, 58 centimeters in diameter made of an aluminum alloy 2 millimeters thick.

A set of antennae was bolted outside of the main body of PS-1. The system comprised four metallic rods, two with a length of 2.4 meters each and the remaining two with a length of 2.9 meters each. All four would spring open into their unfurled position at separation from the launch vehicle, at an angle of 35° with the satellite’s main axis. When the satellite was actually stacked on the launch vehicle, these antennae were folded inside a cone-shaped adaptor (46° angle) and held down by eight small latches. The total mass of the satellite was 83.6 kilograms, of which 51.0 kilograms was simply the power source.

It is worth remembering the names of the designers, engineers, and technicians who worked on this satellite. The object (officially known as “PS-1”) was designed in OKB-1’s Department No. 9 under Korolev and Tikhonravov’s direct supervision. The core group included: V. I. Petrov and A. P. Frolov (design and layout); O. V. Surguchev (thermal mode support); M. V. Kraiushkin and Iu. A. Bogdanovich (calculations for antennae systems); N. A. Kutyrkin (design of antennae systems); F. V. Kovalev, B. G. Shumakov, Iu. S. Karpov, and V. K. Shevelev (power control system); B. M. Popov (pressure and temperature measurement systems); A. M. Sidorov (pressurization maintenance); V. V. Molodtsov (installation of PS-1 in the nosecone and conceptual drawings of the payload shroud); and V. P. Kuz’min (payload shroud jettisoning system and system for separating PS-1 from the launch vehicle).17

page 2: Sputnik’s radio transmitters >>