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Strela

The lowest level of the three-tier communications satellite constellation is now populated with two distinct systems devoted to military and government communications. Both systems are assessed to be simple store-dump repeaters which are particularly useful in relaying non-essential traffic between the Russian Federation and overseas stations or forces.

The first system debuted in 1970 and consists of 750-1,000 kg satellites deployed at mean altitudes of 800 km in three orbital planes inclined 74 degrees to the equator and spaced 120 degrees apart. These Strela 2 spacecraft are launched separately by the Kosmos launch vehicle from the Plesetsk Cosmodome into each orbital plane at intervals of 24-36 months in recent years. The activity of satellites can be monitored via a characteristic CW beacon emitted on a frequency of 153.660 MHz.

At the beginning of 1993 the principal members of this constellation were Kosmos 2112, Kosmos 2150, and Kosmos 2208. On 16 June 1993 Kosmos 2251 was launched to replace the oldest of the trio. Likewise, on 20 December 1994, Kosmos 2298 was placed into orbit to takeover from the then-oldest member, Kosmos 2150.

Also, debuting in 1970 was a communications system of small (61 kg, 0.80 m by 0.75 m) relay satellites launched from Plesetsk by the Kosmos booster in groups of eight. Although the mean altitude of this constellation was near 1,500 km, each set of eight Strela 1 satellites was normally dispersed into slightly elliptical orbits with mean altitudes between 1,430 km and 1,490 km. The intentional orbital period differences of about 0.15 min ensured that the satellites would become randomly spaced about the orbital plane shortly after launch. Unlike the lower altitude constellation, this network relied on a single orbital plane with an inclination of 74 degrees which was replenished on the average once each year. The last mission in this program was in June, 1992, and the network has now been superseded by the more modern and capable Strela 3 system.

The Strela 3 system, which began missions in 1985, is launched by the Tsyklon-3 booster from the Plesetsk Cosmodrome into orbits near 1,400 km at inclinations of 82.6 degrees with six spacecraft stacked atop each launch vehicle. Two orbital planes, spaced 90 degrees apart, apparently each contain 10-12 operational spacecraft. Normally, two missions are conducted per year, suggesting an average spacecraft life-time of approximately 24 months. Four missions were undertaken during 1993-1994: Kosmos 2245-2250 (May, 1993), Kosmos 2252-2257 (June,1993), Kosmos 2268-2273 (February, 1994), and Kosmos 2299-2304 (December, 1994). The 220-kg spacecraft have a diameter of 1.0 m and a main bus height of 1.5 m. A gravity-gradient beam is extended on-orbit to provide passive attitude stabilization.

Sources and Resources

• Adapted from: Europe and Asia in Space 1993-1994, Nicholas Johnson and David Rodvold [Kaman Sciences / Air Force Phillips Laboratory]

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