In 1957, Sergey Pavlovich Korolev wrote to the Central Committee of the Communist Party of the Soviet Union and the Council of Ministers of the USSR:
"We ask for permission to prepare and conduct test launches of two rockets adapted for the satellite variant in the period from April to June 1957, before the official start of the International Geophysical Year. The rocket can be adapted for launching the satellite variant, having a small payload in the form of instruments weighing about 25 kg.
...A satellite weighing about 1200 kg is being developed, which includes a large amount of diverse scientific research equipment, experimental animals, etc. The first launch of this satellite is scheduled for 1957, and considering its complexity, it might be conducted at the end of 1957..."
Yes, the first satellite developed was a heavy one with a complex set of equipment. The proposal to launch a light, simple satellite emerged during the peak of work on the heavy satellite, and since this proposal was accepted, the heavy satellite was destined to be the third one to ascend into space.
What prompted Korolev to make this unexpected proposal?
In 1957, the International Geophysical Year was announced. According to the scientific research program, the Soviet Union announced its planned satellite launches. By mid-1957, our country had created a launch vehicle for placing satellites into orbit, and the theory for launching into low Earth orbit had been developed. However, launching a satellite into orbit is not everything. Spacecraft must serve science and be tools for research where traditional methods are impossible. To achieve this, the most important question needed to be solved: transmitting scientific information from the satellite and receiving it on Earth. At that time, scientists did not know if radio waves from high altitudes could "penetrate" the Earth's ionosphere and if radio signals would reach without distortion. Moreover, the characteristics of the Earth's atmosphere at hundreds of kilometers from its surface were not well studied. A satellite with the simplest shape — spherical, equipped with radio transmitters, would provide answers to these urgent questions. It was simpler to manufacture and could be made faster than a complex space laboratory. That is why Korolev's proposal was met with approval.
Thus, the first artificial Earth satellite was born — "PS-1", as its developers named it, or "Simplest Satellite — 1". But this "simplicity" was not so simple. The equipment installed on the satellite was "accustomed" to working in ordinary Earth conditions — under atmospheric pressure, normal gravity, and temperatures, which are so natural for everything born and created on Earth. In spaceflight, all these conditions are absent — there is a vacuum, weightlessness, scorching solar rays, or conversely, cosmic cold. Thus, at least partial comfort for the instruments had to be provided through technical solutions. Firstly, atmospheric pressure. It could be maintained constantly if the container was completely sealed. From a technological perspective, the simplest method is a welded "ball". However, this option was unsuitable for many reasons. Even if the equipment was initially assembled and attached to the shells, then the shells welded, the thin electronic devices would fail from overheating. Moreover, during Earth tests, failed instruments could not be replaced. Hence, the container had to be separable. It was made this way — from two half-shells connected by bolts, with a special rubber gasket ensuring hermetic sealing in space. The equipment installed on the frame consisted of two transmitters operating at different frequencies, powered by chemical batteries.
To ensure normal temperature inside the nitrogen-filled container, the satellite's outer surface was polished and specially treated. Additionally, a fan was installed in the container to maintain nitrogen circulation in weightlessness.
Special sensors installed inside the container monitored the pressure and temperature and transmitted the data to Earth in coded form through radio transmitting equipment.
After ground tests confirmed the container's hermeticity and the equipment's reliability, the satellite was transported to the launch site on October 4, 1957. The tested and fueled launch vehicle with the satellite mounted in its head section stands on the launch pad. At 22:28 Moscow time, the rocket with the world's first artificial Earth satellite was launched, opening humanity's path to space.
Hardly returning from the launch site, Korolev gathered engineers and designers, setting them the seemingly impossible task: to create a satellite capable of sending an animal into orbit within a month. It was too early to aim for human spaceflight, but it was possible and necessary to start research related to the prolonged stay of a living being in space.
Developing this satellite maximally utilized the experience of launching animals on high-altitude rockets and creating the first satellite. This allowed the second artificial Earth satellite, with a cabin equipped with everything necessary for life, carrying the dog Laika, to be launched into orbit exactly one month later, on November 3, 1957.
While developing and launching the first satellites, work on the heavy satellite continued, which was more advanced in both design and equipment composition. Developing the satellite considered various specific requirements related to conducting different scientific experiments and placing diverse scientific and measuring equipment, and the experience of the first satellites in low Earth orbit. The radio telemetry system was improved, becoming multi-channel. The thermal regulation system significantly improved: the thermal regime was regulated not only by forced gas circulation in the satellite but also by changing the emissivity coefficient of its surface. A program-timed device was installed onboard for automatic control of all scientific and measuring equipment. In short, a comprehensive automatic scientific laboratory was prepared for orbital flight.
The launch of the third Soviet artificial Earth satellite was conducted on May 15, 1958. During the flight of this satellite, solar corpuscular radiation, photons in cosmic rays, micrometeors were registered, the Earth's magnetic field, heavy nuclei, and the intensity of primary cosmic radiation were studied.
In summary, it can be said that the first Soviet artificial Earth satellites provided information on the transmission of radio waves from space vehicles, the density of the atmosphere at high altitudes, some characteristics of outer space; the first data on the behavior and life of animals in space flight; confirmed the correctness of engineering solutions in creating space technology.
MARINA MARCHENKO, engineer
The drawings depict artificial Earth satellites: the first (bottom left), the second (left), and the third (top). The diagram of the third satellite has numbers indicating: 1 - magnetometer; 2 - photomultiplier for recording solar corpuscular radiation; 3 - solar panels; 4 - photon registration device in cosmic rays; 5 - magnetic and ionization manometers; 6 - ion traps; 7 - electrostatic flux meters; 8 - mass spectrometric tube; 9 - device for registering heavy nuclei in cosmic rays; 10 - device for measuring the intensity of primary cosmic radiation; 11 - sensors for registering micrometeors.