| Molniya-1 | ||
This was the first Soviet communications satellite, using the twelve-hour elliptical orbit later dubbed a 'Molniya orbit'. Korolev's OKB-1 began development of Molniya in 1960. It was initially intended as an experimental spacecraft to test the utility of such a satellite for command and control of the armed forces. Existing tropospheric communication Gorizont ground stations required minimal modification for use with Molniya. Initial flights proved Moscow-Vladivostok strategic communications in 1965 to 1967. It quickly proved the new technologies of automatic satellite control and three-axis stabilization. The design was so successful that it was put into production for governmental and military use, and subsequent modifications continued in service well into the 21st Century. Molniya orbits required less rocket power to achieve than a geosynchronous orbit, and were better suited to communications with northern latitudes. Since satellites in such an orbit move very slowly at apogee, they appear to 'hover' for hours at a time over northern latitudes. The disadvantage was that the sending/receiving dish must track the satellite, whereas for a geosynchronous satellite a fixed dish could be used. Preliminary work on the Molniya-1 communications satellite began in 1960. Full development was authorized by government decree on 30 October 1960. Three such satellites could provide long-distance communications coverage for the entire Soviet Union. Original designed life was 1.5 to 2.0 years. Development was completed in May 1963. The satellite consisted of a hermetically sealed, pressurized main section with 2.5 cubic meters internal volume. This kept the electronic components at a stable temperature during the day-night cycle. The spacecraft's orientation system pointed the solar panels at the sun and the antenna at the earth during communications session. Gyroscopic stabilizers pointed the spacecraft to within 10 degrees. An optical sensor was used for antenna pointing. The Alfa on-board retransmitter operated on the 10 m band in both simplex and duplex modes. Main propulsion was provided with an engine of 200 kgf, with AK-20 nitric acid and UDMH propellants. Total impulse delivered by the three-chamber motor was 8,000 kg-sec, with a specific impulse of 290 seconds. The spacecraft had a span of 8 m across its solar panels and an initial mass on-orbit of 1650 kg. The first two launches, on 2 January and 6 June 1964, were unsuccessful. The first successful launch only came on 14 October 1965. After checks the spacecraft began work in January 1966. The last communications session came on 18 February 1966; thereafter the solar cells deteriorated to the point of inoperability. The first spacecraft completed 30 hours worth of communications in 113 sessions. The system was transferred from Korolev's OKB to Reshetnev in Krasnoyarsk for further development and production. In 1968 operational use of Molniya 1 began. It provided strategic control of the RSVN, Long Range Aviation, Navy, through use of the satellite system Molniya 1-Korund and the Ruchey communications system. The externally similar but internally upgraded Molniya 1T replaced the original model in production from 1975. The full constellation in Soviet times consisted of eight spacecraft, in four orbital planes, with ascending node / 'hovering' points above 60 degrees North every 90 degrees from 10 degrees East. Typical orbit: 1507 x 39305 km, 63.2 deg inclinaton. Length: 4.40 m (14.40 ft). Maximum Diameter: 1.40 m (4.50 ft). Span: 8.20 m (26.90 ft). Mass: 1,650 kg (3,630 lb). RCS Impulse: 78 kgf-sec. Main Engine: KDU-414. Main Engine Thrust: 1.960 kN (441 lbf). Main Engine Propellants: Nitric Acid/UDMH. Main Engine Isp: 290 sec. Electrical System: Solar panels. Electric System: 1.30 average kW. Associated Launch Vehicle: Molniya 8K78, Molniya 8K78M, Proton 8K82K / 11S86. Molniya-1 Chronology
Bibliography and Further Reading
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