Soviet orbital trick



    The history of astronautics, like any other industry, contains examples of witty decisions when the desired goal was achieved in a beautiful and unexpected way. The USSR / Russia was not lucky with the availability of a geostationary orbit. But instead of reaching it with heavier missiles or trying to reduce the mass of the payload, the developers dawned on the idea of ​​using a special orbit. About this orbit and satellites that still use it, our today's story.

    Physics


    Speaking of geostationary and highly elliptical orbits, it is necessary to recall such a concept as the inclination of the orbit . In this case, the inclination of the orbit is the angle between the plane of the equator of the Earth and the plane of the satellite’s orbit:



    If we start from the cosmodrome and begin to accelerate strictly to the east, then the resulting orbit will have an inclination equal to the latitude of the cosmodrome. If we start to accelerate, deviating to the north, then the resulting inclination will be greater. If we, having thought that this should reduce the inclination, begin to accelerate to the southeast, the resulting orbit will also have a greater inclination than our latitude. Why? Look at the picture: during acceleration strictly to the east, the most northern point of the orbit projection (blue line) will be our spaceport. And if we accelerate to the southeast, then the northernmost point of the projection of the resulting orbit will be north of our cosmodrome, and the inclination of the orbit will be greater than the latitude of the cosmodrome:



    Conclusion: when the spacecraft starts, the initial inclination of its orbit cannot be less than the latitude of the cosmodrome.

    In order to enter the geostationary orbit (0 ° inclination) it is necessary to zero the inclination, but this requires additional fuel (the physics of this process is a separate interesting conversation) The Baikonur Cosmodrome has a latitude of 45 °, and, considering that the spent missile stages should not fall into China, rockets are launched northeast on routes with an inclination of 65 ° and 51.6 °. As a result, the 8K78 four-stage launch vehicle, which launched one and a half tons to the moon, and almost a ton to Mars, could bring only ~ 100 kg to the geostationary orbit. To fit into such a mass a full-fledged geostationary communications satellite in the early 60s, not a single country could. It was necessary to invent something else. Orbital mechanics came to the rescue. The higher the satellite’s height, the slower it moves relative to the Earth. At an altitude of 36,000 km above the equator, the satellite will constantly hang over one point on the Earth (the geostationary orbit also works on this idea). And if we put the satellite into orbit, which is an elongated ellipse, then its speed will vary greatly. At the pericenter (the point of orbit closest to the Earth) it will fly very fast, but in the area of ​​the apocenter (the most distant orbit point from the Earth) it will practically freeze for several hours. If the points mark the satellite path with an interval of one hour, we get the following picture:



    In addition to almost immobility, at high altitude, the satellite will see a vast area of ​​our planet and will be able to provide communication between remote points. A large inclination of the orbit will mean that even in the Arctic there will be no problems with signal reception. And if you choose an inclination close to 63.4 °, then gravitational interference from the Earth will be minimal, and in orbit it will be possible to be practically without correction. So the orbit “Lightning” was born with the parameters:

    1. Pericenter: 500 km
    2. Apocenter: 40 000 km
    3. Inclination: 62.8 °
    4. Period of circulation: 12 hours

    If we were on a satellite flying in such an orbit, we would see the Earth like this:



    Embodiment in the gland


    The 8K78 rocket could launch as much as 1600 kg into a highly elliptical orbit. It was a happiness for developers - it was possible to make a powerful satellite with great capabilities and at the same time “wipe its nose” with the Americans, whose communication satellites did not exceed 300 kg in mass. The resulting apparatus impressed with its characteristics:



    The satellite equipment included three repeaters with a power of 40 W and two standby power of 20 W, and electricity for them was generated by solar panels with a total power of one and a half kilowatts. To receive and transmit data, two controllable parabolic antennas with a diameter of 1.4 meters were used. The device was controlled by a transistor program-time device, the ancestor of modern computers, and the orientation was supported by a unique three-degree power gyrop. The control system implemented complex flight mode algorithms with a triaxial orientation. At the working site, the apparatus maintained a constant orientation by solar batteries to the Sun, accompanying the Earth with controlled main antennas. Having completed the working section, the apparatus rotated according to the infrared vertical data until it occupied a position parallel to the orbital velocity vector in the pericenter. In the area of ​​the pericenter, according to the commands stored in his memory, he could make orbit correction.


    Top view, clearly visible cone of the propulsion system and balloons of compressed nitrogen for the orientation system.


    Bottom view, visible solar panels, sensor block at the end and antennas

    It was assumed that the period of active existence of the device will exceed one year, the figure, at that time, is fantastic. The device was called "Lightning", and, looking ahead, let's say that it turned out to be so epoch-making that both the orbit and the 8K78 launch vehicle were named in his honor.

    Exploitation



    Launch vehicle "Lightning-M", a descendant of the launch vehicle "Lightning"

    At that time, the start of operation could not be easy. On June 4, 1964, the first Lightning did not reach orbit due to a launch vehicle accident. On August 22, 1964, the second spacecraft was successfully launched close to the calculated orbit. But the trouble is that both main antennas, which were supposed to duplicate each other, did not open. The investigation found that during the tests on one of the antennas, damage to the cable insulation was detected, and, according to the designer, the antenna rods were additionally wrapped with vinyl tape. In space, in the shadow of solar panels, the tape froze, and the springs, which had difficulty opening the antennas, could not overpower the frozen plastic. The second "Lightning" was lost. For the future, the problem was easy to fix, the springs on the antenna rods were replaced by electric motors, which were guaranteed to fully reveal the antennas. Finally, On April 23, 1965, the third Lightning was successfully launched and turned out to be fully operational. There was a nervous moment when the main relay did not want to turn on the first time, but, after several painful minutes of continuously sending commands from the Earth to turn on the repeater, it still turned on. Between Moscow and Vladivostok, a connection was established through the first Soviet relay satellite:


    The first television footage transmitted using Lightning.

    A large signal power meant that large antennas were not needed for its reception, and relatively small Orbita pavilions were built around the country: The





    northern and eastern parts of the USSR were quickly covered by a network of satellite broadcasting stations:



    A satellite television from a technical miracle quickly became commonplace, the chairman of the regional committee in the Far East immediately declared that Brezhnev would personally complain in case of problems with broadcasting. By 1984, the number of Orbit stations exceeded a hundred, making Soviet satellite TV available even in small towns. The stations relayed the Moscow signal to a local television center, which, in turn, was already serving a significant area.

    The first Lightning satellites could not cross the line of one-year life. Due to the fact that the satellite flew four times every day through radiation belts, solar panels began to rapidly degrade. The first "Lightning" was able to live from April to November. Redundant solar panels were added to the satellite’s structure, which were opened if necessary after major degradation. Already, "Lightning" No. 7 was able to actively exist from October 1966 to January 1968. For Soviet satellites, this was a very long time.

    "Lightning" was developed in the Design Bureau S.P. Korolev, and already in 1965, production began to be transferred to Krasnoyarsk “branch number 2” under the leadership of Mikhail Reshetnev. From this began the glorious history of the enterprise, now known as AIS IS. Academician Reshetnev. The devices "Lightning" actively developed. The parabolic antenna has been replaced by a four-helix:



    Interesting test frames and a story about a four-helix antenna:




    Additional solar panels The

    devices switched to the centimeter wave range, learned to broadcast not to the whole country, but to separate time zones, the number of communication channels and their throughput constantly increased. Over time, the "Lightning" ceased to be used for civilian broadcasting and became mainly military communications satellites. The last device of the Lightning family, Lightning-3K, was launched in 2001.

    Today and tomorrow


    Civil TV broadcasting in the USSR / Russia eventually switched to a geostationary orbit. A more load-bearing Proton launch vehicle appeared, which began to launch satellites to the geostationary station in 1975. The Orbit Pavilion demanded a twelve-meter mobile antenna and lost to satellite “dishes”, which are now found everywhere. The Lightning satellites ended their lives. But the orbit of Lightning did not die. It is in demand for our high latitudes, and now Meridian communications satellites are flying on it. Since 2012, the Arctic meteorological system has been developed. The unique properties of the orbit are also used across the ocean - the American military satellite NROL-35, supposedly related to the satellites of the missile attack warning system and launched in December 2014, was launched precisely into the Lightning orbit. Who knows, maybe the lightning in the hands of the girl on the mission logo is a hint of the name of the orbit?



    A variant of the Molniya orbit, the Tundra orbit with an apocenter of 46-52 thousand kilometers and a one-day orbital period, is used by three Sirius XM radio communication satellites and the QZSS Japanese navigation system.

    In the future, the Lightning orbit will not be forgotten. The geostationary orbit is overloaded, as an option, satellites can begin to go into highly elliptical orbits. And even beyond the borders of the Earth, the invention of Soviet ballistics can be used: in the project of a manned mission to Mars HERRO for real-time control of robots on the surface it is proposed to use an analog of the Lightning orbit:



    Additional materials


    When writing a publication, the following were used:


    By the tag "inconspicuous difficulties" - missiles, engines, launch facilities, sensors, orientation systems and more.

    KDPV - painting by A. Leonov "Lightning - a space relay"

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