Tselina (rus. Целина) is a Russian, formerly Soviet, military space-based radio surveillance system. It is capable of determining the exact location of radio-emitting objects and also their type, modes of operation, and how active they are. For instance, preparation for a military operation may raise the activity of the radio communications. Detection of these communications by a space-based surveillance system can provide early warning of this activity, warning that may be unavailable by other means.
Initially divided into "overview" (Tselina-O) and "detailed" (Tselina-D), since about 1980 the system has been integrated into a single satellite, Tselina-P, which is also known as Tselina-2. The system primarily focuses on the enemy radar equipment. Tselina has been numbered as part of the Kosmos series. In total 130 Tselina satellites have been launched.
- Tselina-O satellites were launched using Kosmos-3M rockets.
- Tselina-D used the Vostok-2M and later the Tsyklon-3.
- Four upgraded Tselina-Ds, named Tselina-R, were also launched using the Tsyklon.
- Tselina-2 satellites were designed for launch on Zenit-2 carrier rockets, however the first two launches used the larger Proton-K / DM-2 as the Zenit was still undergoing development. The most recent launch used the modernised Zenit-2M rocket.
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