Early warning satellites provide an advance warning of missile attacks through the detection of missile exhaust plumes.
Electronic intelligence (elint) satellites pick up and record radio transmissions and radar transmissions whilst they are over foreign territory and play this back over friendly territory. The information gained in this manner gives an insight into the strategy of the opposing powers and also reveals the location of the radar sites.
Ocean surveillance satellites locate and monitor the movements of naval vessels by means of electronic equipment.
Early Warning Series
Tests commenced in 1972 and a limited operational system capability was not achieved until 1976. In 1980 a fully operational system of nine satellites, referred to as Oko, was being established, an effort which was not completed until 1988 as a number of satellites ceased operation after a short time, were in incorrect orbits or drifted out of the correct orbit.
In 1975 an Oko satellite designated as Kosmos-775, was placed in a geostationary orbit over 24∞ W. Since no further such satellites launched, it may be assumed that this launch constituted a test which was not successful. As the USSR already had the capability to place satellites in a geostationary orbit, it may be assumed that the sensing equipment was not satisfactory at the time.
About nine years later a series of satellites was placed in geostationary orbit which, it has been suggested, have a combined early warning and elint objective. Known as the Prognoz system, it is likely that these satellites were dissimilar to Kosmos-775.
To date, western observers have not been able to determine generations of early warning satellites although there is little doubt that such generations do exist.
Elint Series
The second type, known as Tselina D, had a mass of 2500 to 3800 kg and a length of about 5 m. The operational system of these satellites consisted of six satellites spaced 60∞ apart and with typical 630 x 650 km orbits and inclinations of 81∞.
The third type of elint satellite, which has been identified as Tselina-2, is believed to have a mass of approximately 6000 kg. They appear to be placed in a higher orbit than earlier satellites and an operational constellation may consist of four satellites although such an assumption can only be confirmed by the passing of time. The type was introduced in 1984. Based on launches this system is currently operational.
Ocean Surveillance Series
The USSR has deployed two distinctive classes of ocean surveillance satellites which are referred to as radar ocean reconnaissance satellites (Rorsat) and electronic ocean reconnaissance satellites (Eorsat) by Western observers.
The latter class undertook passive monitoring of radio communications which, except during periods of complete radio silence, will occur in association with naval vessels.
As now new Rorsats have been launched since 1988 it can be assumed that the surveillance equipment on board of the Eorsats has been improved over time.
The Rorsats, also known as Upravlyaemyi Sputnik - Aktivny (US-A), were first launched in 1967. The satellites are believed to have been equipped with sideways looking radar and could detect and identify naval ships. They were deployed in typical orbits of 250 x 260 km with an inclination of 65∞. During their operational life these orbits were maintained through the use of ion thrusters. The power requirement for the US-A satellites was provided by a Topiaz thermionic nuclear reactor which, at the end of its operational life, was separated from the main satellite and boosted into a higher orbit of approximately 9000 x 1000 km.
The Upravlyaemyi Sputnik - Passivny (US-P) series of Eorsats operate in circular orbits of 435 km with an inclination of 65∞. Like the Rorsats, their orbits are maintained by micro thrusters but the Eorsats are powered by solar cells.
It is believed they are capable to provide target data with an accuracy of approximately 2 km to anti-ship missile platforms. The first US-P was launched in 1974 and a second generation, placed in a higher orbit, was identified from 1987.