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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Artificial satellites of the earth. History of invention and production
Directory / The history of technology, technology, objects around us An artificial Earth satellite (AES) is a spacecraft revolving around the Earth in a geocentric orbit. To move in orbit around the Earth, the apparatus must have an initial velocity equal to or greater than the first cosmic velocity. AES flights are carried out at altitudes up to several hundred thousand kilometers. The lower limit of the satellite flight altitude is determined by the need to avoid the process of rapid deceleration in the atmosphere. The orbital period of a satellite, depending on the average flight altitude, can range from one and a half hours to several years. Of particular importance are satellites in geostationary orbit, the period of revolution of which is strictly equal to a day, and therefore, for a ground observer, they "hang" motionlessly in the sky, which makes it possible to get rid of rotary devices in antennas. The concept of a satellite, as a rule, refers to unmanned spacecraft, but near-Earth manned and automatic cargo spacecraft, as well as orbital stations, in fact, are also satellites. Automatic interplanetary stations and interplanetary spacecraft can be launched into deep space both bypassing the satellite stage (the so-called right ascension) and after a preliminary ascent to the so-called. the reference orbit of the satellite.
The launch of the first satellite in the USSR began to be thought about even at the time when work was underway on the R-7 ballistic missile. In 1956, a group of scientists headed by academician Mstislav Keldysh was formed, which was instructed to develop a program of scientific experiments for the first artificial satellite of the Earth. After a preliminary analysis of all the onboard systems that this satellite was supposed to be equipped with, it turned out that it was impossible to fit into a mass of less than 1250 kg (the mass of one shell was 250 kg, the power supply system was 450 kg; in addition, massive antennas had a lot of weight ). The rockets that existed then could not communicate the first cosmic velocity (about 8 km / s) to such a heavy apparatus. Then, at the end of 1956, one of Korolev's employees, Mikhail Tikhonravov, proposed a project for a simpler and lighter satellite with a mass of about 80 kg. In June 1957, drawings of the final layout of this satellite were ready, and at the end of August, its testing began. To put the satellite into orbit, the Korolev design bureau developed a special two-stage rocket with a total mass of 7 tons based on the R-267, which consisted of four side rocket blocks of the RD-107 rocket engine and one central rocket engine of the RD-108 rocket engine. All engines at the start were switched on at the same time. 120 seconds after the launch, the side blocks were discarded (by this time the second stage had reached a height of 50 km and had a speed of 2,3 km/s). The central unit continued to work for another 180 seconds. At an altitude of 200 km, the central unit was turned off, after which the satellite was separated from it with the help of a spring pusher, dropped the protective heat shield, and began free flight. The successful launch of the rocket took place on October 4, 1957. This day opened the beginning of a new space age in the history of the Earth. The first satellite marked a key point in the development of technology. On the one hand, it symbolized the completion of a difficult stage in the development of ballistic missiles, and on the other hand, it was the embryo from which all later space technology grew.
The satellite had the shape of a sphere with a diameter of 580 mm. Its mass was 83,6 kg. Radio transmitter antennas in the form of four rods were installed on the outer surface of the ball. The length of two of them was 2,4 m, the rest - 2 m. The rods were connected to antenna insulators fixed to the satellite body with the help of hinges, which made it possible for them to turn at a certain angle. All equipment, together with energy sources, was housed in a sealed aluminum alloy case. Before launch, the satellite was filled with nitrogen gas. To maintain a stable internal temperature, a nitrogen forced circulation system was developed. Two radio transmitters were connected to the antennas, each emitting the same signal at its own frequency, similar to a telegraph one. Sensitive sensors were placed inside the case, which somewhat changed the transmitted signal (the frequency of transmitted pulses and their duration) with changes in temperature and pressure inside the satellite. The power of the radio transmitters was sufficient for the confident reception of their signals by all radio amateurs of the globe. The power source was supposed to ensure the operation of all equipment for three weeks. Already on November 3, 1957, the second Soviet satellite weighing 508 kg was launched into space. It was the last stage of the carrier rocket, on which scientific measuring equipment and a compartment with the dog Laika were placed in several containers.
In front of the satellite was a spectrograph for studying the Sun, a spherical container with radio transmitters, and a pressurized cabin with a dog. The rocket body housed two instruments for studying cosmic rays. By design, the spherical container was similar to the first satellite. Here, in addition to transmitters, there was a power source and various sensors. The hermetic cabin in which Laika was placed looked like a cylinder. A plexiglass porthole was arranged on its removable bottom. The cabin, made of aluminum alloys, had a feeding device, air conditioning, regeneration units and a thermal management system. Regeneration took place with the help of chemical elements that absorbed carbon dioxide and released oxygen. Special sensors recorded the pulse, pressure and breathing of the dog. All this, as well as information about the temperature and pressure in the cabin, was reported to Earth using special equipment, which was turned on by a clock programming device. The observation program was designed for seven days, but even after that the flight of the satellite continued for many more days. Only on April 14, 1958, having made about 2370 revolutions, the second satellite burned up in the atmosphere. At that time, the third satellite, the American Explorer 1, was already flying in space. The reason why the American satellite was not the first or even the second in space has not only a technical background. In 1955, when the US government decided to prepare for the launch of the satellite, three competing programs were proposed, each of which was backed by its own powerful military department: the Army, Air Force and Navy. In the end, preference was given to the Avangard project of the Navy, which received privileged funding. Meanwhile, the army already at that time had the best American Redstone missile, created under the leadership of Brown. (Brown was then head of the Redstone Arsenal, where the missile was developed.)
In September 1956, the Army successfully launched the Jupiter-C four-stage ballistic missile, which used the Brownian Redstone as the first stage and the Baby Sergent solid propellant rockets as the second, third and fourth stages. Three stages of this rocket were natural, and the fourth carried sand in the tanks instead of fuel. This stage reached a height of 1094 km. Later, they repeatedly tried to prove that if the fourth stage had been refueled, it could well have become the first satellite, and the space era would have begun a year earlier. But be that as it may, this did not happen. Meanwhile, the Avangard project, which was plagued by failures from the very beginning, ended in a scandalous failure: upon launch on December 6, 1957, the Avangard rocket, barely leaving the launch pad, fell to the ground within the launch pad and burned out. After that, in order to save prestige, it was decided to launch a satellite based on the Redstone rocket. The Explorer 1 satellite was built in extreme haste at the Jet Propulsion Laboratory at Caltech. The weight of the satellite was 8,21 kg, and the equipment accounted for 5 kg. In addition to the Geiger counter, there was a microphone on board for registering meteorite particles, temperature sensors, radio transmitters and power supplies. The launch took place on January 31, 1958 and was successful. The satellite has been in orbit for eight weeks. Despite its diminutive size, Explorer 1 made important observations. It was thanks to his messages that the radiation belt surrounding the Earth at an altitude of more than 1000 km was discovered. In the same year, on May 15, the USSR launched its third satellite. It could already be called a real automatic scientific station. The length of the satellite was 3,5 m, diameter - 1,5 m, weight - 1327 kg, and the scientific equipment accounted for 968 kg. The device and design of this satellite were worked out much more carefully than the first two. To automatically control the operation of all scientific and measuring equipment, an electronic time-programming device was installed on it, made entirely on semiconductor elements.
In addition to the onboard power source, the satellite was equipped with a solar battery. The voltage created by this battery was greater than that of the onboard battery, so all the equipment on the sunny side was powered by it. Thanks to this, the third satellite was operated much longer than the first two - it was in flight for 691 days, and the last signal from it was received on April 6, 1960. The first spacecraft were distinguished by their individuality. Even without delving deeply into their design, one could immediately tell from the appearance alone that these are completely different devices. But the devices, made each time on an individual order, were expensive. Therefore, in subsequent years in the USSR, it was decided to switch from individual production of satellites to serial production. Cosmos became such a serial Soviet satellite. On March 16, 1962, the first satellite of this series was launched. Author: Ryzhov K.V.
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