Lunar eclipses
When, when moving around the Earth, the Moon falls into the cone of the earth’s shadow, which is cast by the globe illuminated by the Sun, a total lunar eclipse…

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Moon exploration
It is not surprising that the first flight of the spacecraft above Earth orbit was directed to the moon. This honor belongs to the Soviet spacecraft Luna-l, which was launched…

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Astronomical picture of the world
For centuries, man has sought to unravel the mystery of the great world "order" of the Universe, which the ancient Greek philosophers called Cosmos (translated from Greek - "order", "beauty"),…

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Communication satellites

Signalers were among the first to receive practical benefits from the launch of satellites. The launch of satellite transponders into near-Earth orbit made it possible to solve the problem of stable all-weather communication in most of the inhabited territory as soon as possible. The first commercial satellite was precisely the communications satellite – Echo-2, launched by the United States in 1964 and which made it possible to organize the transmission of television programs from America to Europe without the use of cable lines. At the same time, its lightning-1 communications satellite was also created in the Soviet Union. After the deployment of the ground-based network of Orbita stations, all regions of our large country gained access to Central Television, and in addition, the problem of organizing reliable and high-quality telephone communications was solved. Lightning communications satellites were located in highly elliptical orbits with an apogee of 39,000 km. For the purposes of continuous broadcasting, a whole group of Molniya satellites flying in various orbital planes was deployed. The ground stations of the Orbit network were equipped with rather large antennas, which, with the help of servos, tracked the satellite in orbit, periodically switching to the one in the line of sight. Over time, in the process of improving the elemental base and improving the technical parameters of airborne and ground-based systems, several generations of such satellites changed. But to this day, the group of satellites of the Molniya-3 family provide information transfer throughout Russia and beyond.

The creation of powerful launch vehicles of the Proton and Delta types made it possible to ensure the delivery of communication satellites into a geostationary circular orbit. Its peculiarity lies in the fact that at an altitude of 35,800 km the angular velocity of rotation of the satellite around the Earth is equal to the angular velocity of rotation of the Earth itself. Therefore, a satellite located in such an orbit in the plane of the earth’s equator, as it were, hangs above one point, and 3 geostationary satellites located at an angle of 120 ° provide an overview of the entire surface of the Earth, with the exception of only the polar regions. Since the task of maintaining its predetermined position in orbit lies with the satellite itself, the use of geostationary spacecraft has significantly simplified the ground-based means of receiving and transmitting information. There is no longer a need to provide antennas with drives – they have become static, and to organize a communication channel it is enough to set them only once, during the initial setup. As a result, the terrestrial user network turned out to be significantly expanded, and information began to flow directly to the consumer. Evidence of this is the multitude of parabolic dish antennas located on residential buildings both in large cities and in rural areas.

At first, when space was “accessible” only to the USSR and the USA, each of the countries cared exclusively about satisfying its own needs and ambitions, but over time it became clear that everyone needed satellites, and eventually international projects began to appear. One of them is the INMARSAT publicly accessible global communications system, created in the late 1970s. Its main purpose was to provide marine vessels with stable communications while on the high seas and coordination of actions during rescue operations. Now mobile communication via the INMARSAT satellite communications system is provided through a portable terminal the size of a small case. When you open the lid of the “suitcase” with a flat antenna mounted in it and point the antenna at the estimated area of ​​the satellite’s location, two-way voice communication is established, and data is exchanged at a speed of up to 64 kilobits per second.

Moreover, today four modern satellites provide communications not only at sea, but also on land, covering a vast territory stretching from the Northern to the Southern Arctic Circle. Further miniaturization of communications and the use of high-performance antennas on spacecraft have led to the fact that the satellite phone has acquired a “pocket” format, not much different from the usual cellular one. In the 1990s, almost simultaneously, the deployment of several mobile personal satellite communications systems began.

First low-orbit ones appeared – IRIDIUM (Iridium) and GLOBAL STAR (Global Star), and then geostationary – THURAYA (Turaia). The Turaiya satellite communications system has so far included 2 geostationary satellites, which make it possible to maintain communications in most of the African continent, on the Arabian Peninsula, in the Middle East and in Europe.

The Iridium and Global Star systems, similar in structure, use constellations from a large number of low-orbit satellites. Spacecraft alternately fly over the subscriber, replacing each other, thereby maintaining continuous communication.

The Iridium includes 66 satellites orbiting in circular orbits (altitude 780 km from the Earth’s surface, inclination 86.4 °), located in six orbital planes, 11 vehicles in each.

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