COSMOS 1733

The Tselina-D (11F619) was one component of two-satellite Tselina ELINT satellite system. Tselina-D provided detailed observation of radio sources detected by the smaller Tselina-O satellites.

Development began during the 1960's, leading to a first launch in 1970. TsNII-108 GKRE (Zaslavskiy) developed the payload while V M Kovtunenko of Yuzhnoye/OKB-586 build the satellite and launch vehicle. Continuing problems prevented the system from becoming operational before 1976.

After the retirement of the Tselina-O component, Tselina-D took over the general ELINT surveillance function in 1984. The final launch attempt in the series took place in 1994, when Tselina-D was replaced by the improved Tselina-2 satellites, which were launched since the mid 1980ies.

Tselina-D and -O spacecraft were operated simultaneously to provide surveillance and detailed observation and classification of radio emitters. Recorded data was stored on board and dumped to groundstations in the USSR.

Tselina-D satellites were operated in six orbital planes, spaced 30° apart. At the end of the system usage, the orbital regime had been reduced to three orbital planes spaced at 60 degrees, complementing the Tselina-2 constellation in four higher-altitude orbital planes spaced 40 degrees apart.

Western observers of the Kettering Group were able to monitor the status of the Tselina-D satellites via their continuous-wave beacons which operated at 153 MHz.

Kosmos 1408 (Tselina-D #38), which was launched in September 1982, was destroyed during a Russian kinetic ASAT weapon test on 15 November 2021, creating a large debris cloud.