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Lead in and basic introduction edit
The Tsikada and Parus are first generation Soviet satellite navigation systems, first deployed in 1974.
Both systems are similar to the United States' Transit
Tsikada was utilized significantly by the Soviet navy and its marine merchants, who were equipped with the automatic-calculating Shkhuna receiving equipment.
Purpose edit
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Navigation information is derived from Doppler-shifted VHF transmissions (approximately 150 and 400 MHz) of satellite position and orbital data. By acquiring fixes from several satellites, a user's location can be calculated with an accuracy of 100 m (Reference 443). The time needed to ascertain one's position is dependent upon the user's latitude and the number of operational spacecraft in orbit. Normally, ten first-generation Russian satellites are transmitting navigational signals, permitting accurate location determination within 1-2 hours. These ten spacecraft are deployed in two complementary constellations.
The Soviets set up a network of navigation satellites similar to the US Transit system, using Doppler location technology and with comparable accuracies. As with the US Transit system, the primary rationale was to provide navigational data to ballistic-missile submarines. Investigations began in the late 1950s, leading to start of a formal development program in 1962. Launch of an initial series of "Tsyklon" experimental satellites began in 1967, with a total of 29 launched into 1978, not counting at least two launch failures.
Search and Rescue edit
A series of Tsikada-type satellites were fitted with an auxiliary COSPAS-SARSAT rescue beacon locator payload, described in more detail at the end of this chapter, and were given the name "Nadezhda (Hope)". An evaluation prototype was launched in 1982, followed by the first launch of an operational satellite in 1983. From the mid-1990s the Nadezhdas were fitted with an improved "Kurs" rescue locater system, and these improved satellites were designated "Nadezhda-M".
Other uses edit
A few satellites involved secondary payloads; in particular, the Tsikada satellite Cosmos 2123 was also fitted with two Russian amateur radio communications transponders.
Development edit
Technical details edit
Typical orbit: 965 km x 1009 km at 83 degrees inclination. Mass: 820 kg (1,800 lb). Associated Launch Vehicle: Kosmos 11K65M.
Originally, designed and manufactured by the Applied Mechanics NPO in Krasnoyarsk, both Parus and Tsikada satellites are now largely produced by the Polet PO in Omsk, where an annual production rate of ten spacecraft has been achieved. The navigational payloads were developed, in part, by the Institute of Space Device Engineering.
Tsikada versus Parus edit
The two names, Tsikada and Parus, often are used to refer to a similar system, but were infact two different levels of satellites. Parus was a secret military system, first launched in 1974 with Kosmos 700, that originally consisted of six satellites distributed in orbital planes spaced 30 degrees apart. This network with is never explicitly referred to by Russian officials and is believed to be primarily dedicated to the support of military forces. However, it was followed soon after by a simplified system for intended for civilian use known as "Tsikada." The later lead Parus to sometimes be referred to as "Tsikada Military" or "Tsikada-M".
The Tsikada system began deployments in 1976 with Kosmos 883 and was accepted into service in 1979; reacheding its full complement of satellites in 1986.
Despite their obvious similarities, Parus military navigation satellites were replaced at a much faster rate - about twice as often - compared to the Tsikada civilian satellites. During 1993-1994, two-thirds of the Parus network was replenished, including many recently launched satellites. Moreover, when the Tsikada orbital planes were developed, they were carefully offset from the Parus' orbits to minimize the time between satellite observations for the military receivers which could process both signals.
The network of Parus satellites (aka Tsikada-M) is never explicitly referred to by Russian officials and is primarily dedicated to the support of military forces. It is believed that the Parus satellites provide a "store-dump" communications relay service for Red Navy surface vessels and submarines. With the continued launch of Parus satellites in a time when both the GLONASS and GPS networks provide faster navigation information, many suspect that military communication is now the primary rationale for the constellation.
Although the last true Tsikada satellite was launched in 1995, the constellation continues to be replenished with a slightly different type of spacecraft. The most recent launch was on the 20th of January, 2005.
Tsikada employs four orbital planes separated by 45 degrees.
History edit
The development program was protracted because it proved difficult to obtain the required location accuracy. Meeting specification required launch of geodetic studies satellites to obtain a more precise gravity map of the Earth. The last 13 Tsyklons were operational prototypes, close to production spec, and were also called "Zaliv".
The Tsyklon series was followed by the fully operational "Tsyklon-B" or "Parus" system. Unlike the wildly varying Transit satellites, the Tsyklon and Parus satellites had similar configurations. Both were in the form of a drum covered with solar cells, with a weighted mast on top for gravity-gradient stabilization, and a what appears to have been an antenna hung off one side near the bottom. They were all launched from the Plesetsk Northern Cosmodrome by the standard Soviet Kosmos 3M medium-lift booster, one satellite per shot, though a few did include small secondary payloads. The developed Parus satellites had a launch weight of about 810 kilograms (1,785 pounds), and were placed into a near-circular orbit of about 1,000 kilometers (620 miles) at a near-polar inclination of 83 degrees
The basis was the Parus / Tsiklon-B doppler navigation system, but allowing asynchronous operation of on-board equipment with only essential equipment receiving a timer interrupt. Development began in 1974 with some preliminary work already accomplished. The Tsikada system provided global navigation for both the Soviet Navy and commercial shipping. Prime contractor was KBPM/Reshetnev. PO Polyot, A S Klinyshkov provided synchronisation equipment. NII Radiopribor under N Ye Ivanov provided cryptography and spacecraft navigation systems. Flight trials began in 1976 from Plesetsk under Admiral A I Rassokho. The launch of Kosmos 1000 on 31 March 1978 marked the beginning of deployment of the operational system. The system was accepted for military service in 1979 by the Soviet Army and VMF. The complete constellation of 22 spacecraft entered service in 1986. The satellite could be launched one per Kosmos-3M or four per Tsyklon-3 booster.
93 Parus satellites have been launched since 1974, not counting two failures. The system was formally accepted into service in 1976, but it appears that the full constellation required 22 satellites and that wasn't achieved until 1980.
By the end of 1994 more than 130 first generation satellites had been launched an average of five per year since 1967.