± 1 km range, 10 min azimuth, 50 min elevation, 5 m/s range rate[4]: 75
Power
Peak power of 1.25 MW per transmitter[2][4]: 75 Radiating power 200 kW[4]: 75 Consumed power 2100 kW[4]: 75
Other names
NATO: Hen House[6] GRAU: 5N15 (Dnestr), 5N15M (Dnestr-M), 5N86 (Dnepr)
Dnestr radar (Russian:Днестр) andDnepr radar (Russian:Днепр), both known by theNATO reporting nameHen House,[note 1] are the first generation of Sovietspace surveillance andearly warning radars.[7] Six radars of this type were built on the periphery of theSoviet Union starting in the 1960s to provideballistic missile warnings for attacks from different directions. They were the primary Soviet early warning radars for much of the laterCold War. In common with other Soviet and Russian early warning radars they are named after rivers, theDnestr and theDnepr.[note 2]
The Dnestr/Dnepr radars were intended to be replaced by the newerDaryal radars starting in the 1990s. Only two of the planned Daryal radars became operational, due to issues such as thedissolution of the Soviet Union. As of 2012, the Russian early warning network still consists of some radars of this vintage. It is likely that all the existing radars will be replaced by the third generationVoronezh radars by 2020.
The Dnestr radar came from work on ballistic missile defence undertaken in the late 1950s and early 1960s. System A, the prototype for theA-35 anti-ballistic missile system, was set up in theSary Shagan testing grounds, in theKazakh SSR.[8]: 123 Work on the system was led by design bureauKB-1 which proposed usingVHF radar RTN (Russian:РТН) and theDunay-2UHF radar. Other alternatives were sought from Soviet industry andRTI proposed using VHF radar TsSO-P (Russian:ЦСО-П) and UHF radar TsSS-30 (Russian:ЦСС-30).[9]
TsSO-P (standing forRussian:центральная станция обнаружения – полигонная meaningcentral detection station – test site) was selected for further development, together with the Dunay-2.[9] TsSO-P had a longhorn antenna 250 metres (820 ft) long and 15 metres (49 ft) high. It had an array with an open ribbed structure and used 200 microseconds pulses. Hardware methods were designed for signal processing as the intended M-4 computer could not run the necessary computations. It was built at area 8 in Sary Shagan and was located at46°00′04.65″N73°38′52.11″E / 46.0012917°N 73.6478083°E /46.0012917; 73.6478083. It first detected an object on 17 September 1961.[9]
KH-7 Gambit US spy satellite image of a Dnestr space surveillance radar atBalkhash Radar Station, 28 May 1967. Note the radar arrays are in straight line.
Dnestr is a Phased array, Azimuth scanning by frequency modulation with no elevation scanning.[10]
TsSO-P was effective at satellite tracking and was chosen as the radar of theIstrebitel Sputnikov (IS) anti-satellite programme. This programme involved the construction of two sites separated in latitude to form a radar field 5,000 kilometres (3,100 mi) long and 3,000 kilometres (1,900 mi) high. The two sites chosen were at the village ofMishelevka nearIrkutsk inSiberia, which was called OS-1, and atCape Gulshad onLake Balkhash nearSary Shagan, which was called OS-2. Each site received four Dnestr radar systems in a fan arrangement.[9][11][12][13]: 421 [13]: 433 [14]
A Dnestr radar was composed of two TsSO-P radar wings joined together by a two-story building containing a joint computer system and command post. Each radar wing covered a 30-degree sector with a 0.5 degree scanning beam. The elevation scanning pattern was a 'spade' with a width of 20 degrees. The radar systems were arranged to create a fan shaped barrier. Of the four radars, called cells (Russian:РЛЯ,romanized: RLYa roughly radio location cell), two faced to the west and two faced to the east. All scanned between +10 degrees and +90 degrees in elevation.[9]
Construction at the two sites started between 1962 and 1963 with improvements in the TsSO-P test model being fed back into the deployed units. They gained an M-4 2-M computer withsemiconductors, although the rest of the radar usedVacuum tubes. The radar systems were completed in late 1966 with the fourth Dnestr at Balkhash being used for testing.[9] In 1968, theDnepropetrovsk Sputnik target satellite,DS-P1-Yu, was used to test the ability of the system.[14][15]
Parallel with the implementation of the Dnestr space surveillance units, a modified version of the original Dnestr units, Dnestr-M radar, was being developed to act as anearly warning radar to identify attacks byballistic missiles. The first two were built at Murmansk in northern Russia (Olenegorsk – RO-1) and nearRiga in the thenLatvian SSR (Skrunda – RO-2). They constituted the beginning of the SovietSPRN network, the equivalent of the NATOBMEWS.[13]: 421 [9][17]
The first Dnestr-M at Olenegorsk was completed by 1968.[9] In 1970, the radars at Olenegorsk and Skrunda, and an associated command centre atSolnechnogorsk, were accepted for service. According to Podvig (2002), it seems they were positioned to identify missile launches from NATO submarines in theNorwegian andNorth Seas.[5]
The Dnestr-M included many improvements over the previous versions such as an increase in thepulse length from 200μs to 800μs which increased the range of objects identified, more semiconductors, and many other scanning and processing changes.[9]
A version of this radar was built at theSary Shagan test site and was called TsSO-PM (Russian:ЦСО-ПМ). After this had completed tests in 1965 it was decided to upgrade nodes 1 and 2 of the two OS sites to Dnestr-M, keeping nodes 3 and 4 as Dnestr. These radars remained as space surveillance radars which scanned between +10 and +90 degrees, comparative to scanning between +10 and +30 degrees for the missile warning radars. A space surveillance network of four Dnestrs and four Dnestr-Ms, and two command posts was formally commissioned in 1971.[9]
Map of Dnepr radar site at Mukachevo. The two arrays are at 196 and 260 degrees (south and west)
Work to improve the radar continued. An improved array was designed which covered 60 degrees rather than 30. The first Dnepr radar was built atBalkhash as a new radar, cell 5. It entered service on 12 May 1974.[2] The second was a new early warning station atSevastopol. New Dneprs were also built atMishelevka and another atSkrunda, and then one atMukachevo. The remaining radars were all converted to Dnepr with the exception of cells 3 and 4 at Balkhash and Mishelevka which remained space surveillance radars.[5][9][13]: 422
All current operational radars are described as Dnepr, and have been updated incrementally.[2][18]
Each Dnepr array is a double sectoralhorn antenna 250m long by 12 m wide.[2] It has two rows ofslot radiators within twowaveguides. At each end of the two arrays, there is a set of transmitting and receiving equipment. It emits a signal covering a sector 30 degrees in azimuth and 30 degrees in elevation, with the scanning controlled by frequency. Four sets mean the radar covers 120 degrees in azimuth and 30 degrees in elevation (5 to 35 degrees).[2]
The Dnepr involved the horn antenna being reduced from 20 to 14 metres in height and the addition of apolarising filter.[9]
These radars have been installed at six different radar stations and as of 2012 are operational at three – Balkhash, Mishelevka and Olenegorsk.[2][18][19] The 1972Anti-Ballistic Missile Treaty required that early warning radars were located on the periphery of national territory and faced outwards. This caused problems when theSoviet Union collapsed in 1991 as many of the radar stations were now in newly independent states.[5][17][20][21] The first station to close was Skrunda, in newly independentLatvia. A 1994 agreement between Russia and Latvia agreed that the two Dnepr radars there would stop working in 1998, and would be fully demolished by 2000.[22]: 129 [23]: 65 [13]: 426
Russia signed an agreement with Ukraine in 1992 allowing it to continue using the Dnepr radars at Sevastopol and Mukachevo. The stations were run by Ukrainian personnel and data was sent to the headquarters of the Russian early warning system in Solnechnogorsk.[24][25] In 2008 Russia announced that it was pulling out of the agreement with Ukraine and that the last data given to Russia from the stations would be in 2009.[26]: 76 [27] The Ukrainian government announced that the stations were to be used part-time for space surveillance.[28][29]
The remaining stations in Russia and abroad are being replaced by theVoronezh radar. The Dneprs in Mishelevka, Irkutsk will close once the second array of the new Voronezh radar is operational.[citation needed] The Dnepr at Olenegorsk, Murmansk will be replaced by a Voronezh as well. It is planned to start construction there in 2017.[19][30]
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^Baev, Pavel (2010). "Neither Reform nor Modernisation: the Armed Forces Under and After Putin's Command". In Galeotti, Mark (ed.).The Politics of Modern Security in Russia. Ashgate. pp. 69–88.ISBN978-0-7546-7408-5.
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