Molniya (satellite)

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Mólniya (in Russian: Молния, in Spanish: "relámpago") was the name of an initially military system, although it also had civil, communications uses by satellite created and operated by the Soviet Union. Initially assigned to the Soviet Union's space program, the system was active from 1965 to 2014 since, after the dissolution of the USSR, the Russian Federation continued its operations.

The satellites used a very eccentric and elliptical orbit which allowed them to be suitable for use in polar regions for long periods since places near the poles cannot communicate with satellites in geostationary orbit. In total they were launched and 164 Molniya satellites operated.

History

At the beginning of the 1960s, the states of Western Europe and America began to launch communication satellites, placing them in geostationary orbits. However, this location was not suitable due to the geographic location occupied by the Soviet Union since it required the use of large quantities of fuel to reach orbit and it was complex to provide the appropriate inclination to receive the signal. Additionally, satellites located in geostationary orbit offer poor coverage in polar areas. For this reason, the OKB-1 Experimental Design Bureau, directed by Sergei Korolev and in charge of launching the system, sought a more favorable orbit that required less energy. Studies found that the project could be achieved by launching satellites that trace a large elliptical orbit with apogee over the territory of Russia.

Features

A satellite with a highly elliptical orbit spends a long time over the designated area of the Earth, a phenomenon known as the "apogee well". This route is also known as the “Molniya Orbit”. To ensure that the apogee position is not strongly affected by orbital perturbations, an inclination of about 63.26º is chosen. This makes the perigee angle constant for a long time. The formula that gives the change in perigee angle per day is the following:

{displaystyle Delta omega _{dia}=4,98^{circ }left({frac {R_{E}}{a}}right)^{frac {7}{2}}{frac {5cos ^{2}i-1}{left({1-varepsilon ^{2}}right)^{2}}}}

The equation becomes zero for an inclination of 63.4º. The Molniya satellites had an orbital period of about 12 hours.

There are American satellites that have used Molniya orbits.

NPO Molniya was the name used by one of many Soviet design offices. The Molniya office was headed by Matus Bisnovat, and specialized in missile development. Molniya was also responsible for the satellite of the same name.

Molniya series 1

The authorization for the Molniya program took place on October 30, 1961, being a project designed and commissioned by the OKB-1 office. Initially based on the Kaur-2 satellite bus, its final design was completed in 1963. On October 4 June 1964 saw the first launch that failed due to a failure in thrust force 287 seconds into the process caused by a jammed servomotor.

On August 22, 1964, the second launch, known publicly as Kosmos 41, took place. It was not completely successful since it reached the planned orbit but the deployment of the satellite dishes could not be completed due to a failure in the release mechanism. Despite this, it remained operational for nine months. The first fully functional satellite, named Mólniya 1-1, was successfully launched on April 23, 1965. Months later, on May 30, 1966, the third satellite of the Mólniya 1 series was able to take the first complete images of planet Earth from space for the first time in history.

The first satellites of the Molniya 1 series were designed for use in television, telegraph and telephone throughout the Soviet Union. They also equipped cameras to carry out meteorological predictions and analysis and, possibly, to search for empty areas suitable for the use of Zenit spy satellites. In 1967 the system was fully functional after the construction of the Orbita ground stations. The useful life of the satellites was estimated at 18 months, due to the deterioration of the solar panels that supplied their energy or orbital disturbances, which forced their constant renewal. In total, 94 Molniya series 1 satellites were launched into orbit, being the last of them in 2004.

Throughout the 1970s the Mólniya 1 satellites, and those of its update called Mólniya 1T, were used primarily for military communications. For those intended for the transmission of civil communications, a new program was implemented, called Mólniya series 2, whose first steps took place in 1971 and its first functional satellite was deployed in 1974.

Molniya series 2

The first satellites of the Molniya 2 series began to be tested in 1971, although the launch of the first operational satellite took place in 1974 from the Plesetsk Cosmodrome. They used the same satellite bus and basic design as the Molniya 1T series satellites with a larger number of users under the military's Unified Satellite Communications System (YeSSS) program. These satellites were used to develop the Soviet national television network, called Orbita, which had been established a few years earlier in 1967. Only seventeen satellites of the Molniya 2 series were launched as they were soon replaced by Molniya 3.

Molniya series 3

Originally called Molniya-2M, the third series of the system began development in 1972 and launches began in 1974. They were based on the KAUR-2 satellite bus that was operated solely from Plesetsk. Previous models were used for civil communications in a similar orbit but with a different purpose than the Molniya-1 satellites whose purpose was military. Starting in the 1980s they were used by the military and in the 1990s they were operated in the same way as the Mólniya 1 satellites. A total of 53 launches of Mólniya 3 series satellites were completed with the last one in 2003.

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