US-P Credit - © Mark Wade

The nuclear-powered Pirs system was abandoned in 1988 after a few test flights due to continued reliability problems and international incidents when the reactor cores of the satellites inadvertently crashed to the earth. Since Tselina-2 was accomplishing the naval SIGINT mission, it would seem that the US-P passive design was modified to allow more ship location and targeting capability, probably using systems and software developed for PIRS-1. A universal version of the US design, perhaps designated US-PU, began flying in 1993 in replacement of both the US-A and US-P earlier generation spacecraft. These modernized spacecraft were stationed at 120 degree intervals on the same orbit, probably to provide an improved signal/target localization capability.

Specifications for the second-generation MKRTs system were developed co-operatively by TZ MO, VMP, GUKOS, and TsNII Kometa (Savin) in 1978-1980. Following approval by NTK and VPK, the development was to have begun in the Eleventh Five Year Plan (1981-1985). A resolution of June 1981 called for completion of a draft project for the Phase 1 Pirs-1 system by the end of 1982.

The complete Ideogramma-Pirs system was to have been deployed during the Twelfth Five year plan (1986-1990). The radio and radiotechnical SIGINT mission of the first generation of naval reconnaissance satellites would be handled by the interservice Tselina-2. The project was given the code name Ideogramma-Pirs. Three OKB's had to collaborate on the draft project due to the use of the new Zenit launch vehicle: NPO Energia, PO Arsenal, and TsKBM. The systems technical specification was delivered to the VMF in September 1982.

Following interagency review, Arsenal presented the draft project to the VPK Military-Industrial Commission on 12 December 1982. General Designer Yu F Valov at PO Arsenal was made responsible in 1983 for the overall space system, while TsNII Kometa solved detailed systems problems. Admiral Gorshkov fiercely resisted relinquishing Navy control of the system despite the desire of the leadership for consolidation of space systems. The overall space system specification was delivered to GUKOS in September 1983, followed by a combined technical proposal. A firm program schedule finally emerged in December 1984. Phase 1 was to be deployed by 1990.

The nuclear-powered Pirs system was abandoned in 1988 after a few test flights due to continued reliability problems and international incidents when the reactor cores of the satellites inadvertently crashed to the earth.

Typical orbit: 420 km circular orbit, 65 deg inclination. Mass: 3,150 kg (6,940 lb). Associated Launch Vehicle: Tsyklon 2.

• 1993 March 30 - Cosmos 2238 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 402 km (249 mi). Apogee: 416 km (258 mi). Inclination: 65.00 deg. Period: 92.70 min. Duration: 567.00 days.

  First launch of new EORSAT, first of at 120 degree intervals on the same orbit with a 0 degree ascending node. Ocean surveillance.

• 1993 April 28 - Cosmos 2244 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 402 km (249 mi). Apogee: 416 km (258 mi). Inclination: 65.00 deg. Period: 92.80 min. Duration: 657.00 days.

  Second launch of new EORSAT, second of three stationed at 120 degree intervals on the same orbit with a 0 degree ascending node.

• 1993 July 7 - Cosmos 2258 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 400 km (240 mi). Apogee: 417 km (259 mi). Inclination: 65.00 deg. Period: 92.80 min. Duration: 603.00 days.

  Third launch of new EORSAT, final of three stationed at 120 degree intervals on the same orbit with a 0 degree ascending node. Ocean surveillance.

• 1993 September 17 - Cosmos 2264 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 401 km (249 mi). Apogee: 417 km (259 mi). Inclination: 65.00 deg. Period: 92.80 min. Duration: 564.00 days.

  EORSAT, first of three to be stationed at 120 degree intervals on the same orbit with a 215 degree ascending node. However cutbacks in program resulted in the constellation not being completed. Ocean surveillance.

• 1994 November 2 - Cosmos 2293 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 402 km (249 mi). Apogee: 418 km (259 mi). Inclination: 65.03 deg. Period: 92.78 min. Duration: 497.00 days.

  Second launch of new EORSAT, second of three to be stationed at 120 degree intervals on the same orbit with a 215 degree ascending node. However cutbacks in program resulted in the constellation not being completed. Ocean surveillance.

• 1995 June 8 - Cosmos 2313 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 410 km (250 mi). Apogee: 419 km (260 mi). Inclination: 65.00 deg. Period: 87.60 min. Duration: 685.00 days.

  EORSAT, first of three to be stationed at 120 degree intervals on the same orbit with a 143 degree ascending node. However cutbacks in program resulted in the constellation not being completed. Ocean surveillance.

• 1995 December 20 - Cosmos 2326 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 406 km (252 mi). Apogee: 415 km (257 mi). Inclination: 65.00 deg. Period: 87.20 min. Duration: 660.00 days.

  EORSAT, placed in 215 degree ascending node orbital slot. Ocean surveillance; also performed astrophysics research.

• 1996 December 11 - Cosmos 2335 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 403 km (250 mi). Apogee: 418 km (259 mi). Inclination: 65.00 deg. Period: 92.80 min.

  EORSAT, second of three to be stationed at 120 degree intervals on the same orbit with a 143 degree ascending node. However cutbacks in program resulted in the constellation not being completed. Still in operation as of December 1997.

• 1997 December 9 - Cosmos 2347 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 403 km (250 mi). Apogee: 417 km (259 mi). Inclination: 65.00 deg. Period: 92.80 min.

  EORSAT, in the 217 degree ascending node slot. Still in operation as of December 1997.

• 1999 December 26 - Cosmos 2367 - Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 404 km (251 mi). Apogee: 418 km (259 mi). Inclination: 65.00 deg.

  Passive naval electronic intelligence satellite. The satellite was placed in an initial 147 km x 442 km orbit at 65 degree inclination. The US-PM's propulsion module fired at apogee to circularize the orbit. Replaced the only previous remaining US-PM satellite which ended operations in November and reentered earlier in December 1999.

• 2001 December 21 - Cosmos 2383 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 404 km (251 mi). Apogee: 415 km (257 mi). Inclination: 65.00 deg.

  Signal Intelligence Satellite. Launch delayed December 19. The booster put the satellite into an initial orbit of 145 x 405 km x 65.0 deg. At apogee the satellite ignited its own propulsion system to increase velocity by about 70-80 m/s and circularize the orbit.

• 2004 May 28 - Cosmos 2405 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb). Perigee: 405 km (251 mi). Apogee: 417 km (259 mi). Inclination: 65.00 deg. Period: 92.80 min.

  Original reported name Cosmos 2407.

• 2006 June 24 - Cosmos 2421 - Program: EORSAT. Launch Site: Baikonur. Launch Vehicle: Tsiklon. Mass: 3,150 kg (6,940 lb).