The equally populous Gorizont satellites are primarily used for domestic and international communications. In use since 1979, the Gorizont constellation established a tenth position in the GEO ring for domestic needs and deployed three Gorizonts (one old, two new) to new locations in support of Rimsat, Ltd., the US-based firm leasing orbital slots from Tonga. In all, four Gorizont spacecraft were launched during 1993-1994, but one was lost due to a Proton launch failure. With no resident spacecraft being retired during the period, the number of active Gorizonts increased by the end of 1994 to 13.
The Gorizont spacecraft possesses an initial mass in excess of 2.1 metric tons and has demonstrated a lifetime of nearly 10 years, although a 5-year service life is more common. The 3-axis stabilized satellite is approximately 2 m in diameter and 5 m long with two large solar arrays capable of generating 1.3 kW of electrical power for the first three years. Seven separate transmission antennas permit a variety of reception patterns for both broad and localized terrestrial regions.
A typical Gorizont communications payload includes six general purpose (TV, audio, facsimile) 6/4 GHz transponders (five 12.5 W and one 60 W), one Luch 14/11 GHz transponder (15 W), and one Volna 1.6/1.5 GHz transponder (20 W). The Volna transponders are INMARSAT-compatible and are extensively used by the Russian merchant marine fleet via the primary control center in the Tomilino suburb of Moscow and the Odessa and Nakhodka ground stations. Gorizont is the primary GEO television rebroadcasting system, supporting all five federation time zones: Zone 1 from 140 degrees E, Zone 2 from 90 degrees E, Zone 3 from 80 degrees E, Zone 4 from 53 degrees E, and Zone 5 from 14 degrees W. These transmissions are handled by Orbita (12-m receiving antenna) and Moskva (2.5-m receiving antenna) ground stations in the 6/4 GHz band. The Moskva Globalnaya system was inaugurated in 1989 using 4-m receiving antennas and serviced by Gorizonts at 96.5 degrees E and 11 degrees W (Reference 290).
The first Gorizont launch attempt in 1993 on 27 May failed due to propellant contamination in the second and third stages, resulting in the spacecraft splashing down in the Pacific Ocean. After the Proton returned to service in late September, two Gorizonts were deployed in the final quarter of the year. Gorizont 28, launched on 28 October replaced Gorizont 21 at 90 degrees E. This allowed Gorizont 21 to be repositioned from mid-November to late-December for the inauguration of a new station at 145 degrees E.
Gorizonts 29 (18 November 1993) and 30 (20 May 1994) were launched for Rimsat, Ltd., to provide communications services in the Pacific region under an agreement signed in 1992 between Rimsat and the Applied Mechanics NPO. Gorizont 29 was located at 130 degrees E, and Gorizont 30 settled in at 142.5 degrees E in accordance with a lease arrangement with Tonga which had been authorized use of those slots by the International Telecommunications Union. The Rimsat network had actually been initiated earlier when Gorizont 17 was transferred from 53 degrees E (where it was a backup to Gorizont 27) to 134 degrees E during late-June and July, 1993. At the close of 1994, Gorizont 17 was still on station but nearing the end of its operational life after six years (References 291-300).
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