US-P (Upravlenniye Sputnik Passivny) was a solar powered EORSAT (Electronic Ocean
Reconnaissance Satellite). It used an passive ELINT devices to track naval vessels from
space by registering their electronic emmissions.
The soviet satellite systems to monitor foreign fleet movements split into two
families, the passive US-P program and the active radar equipped satellites designated US-A which carried nuclear reactors.
Both types shared the same US bus, which provided maneuvering capabilities to the
spacecraft. As the passive detection systems did not need as much power as the active
radar system of the US-A, it was fitted with solar arrays.
The satellites were built by the KB Arsenal design bureau in Leningrad/St.-Petersburg, and the payloads by the Central Scientific Radiotechnical Research Institute or TsNIRTI in Moscow.
The US-P were placed into a 420 km orbits inclined 65 degrees by the Tsiklon-2 booster. Systems aboard the 3300 kg
satellite included the Radio-Technical Reconnaissance system and systems for electronic
camouflage and self-protection. An engine unit maintained the orbital altitude and made a
final deorbit of the satellite at the end of the mission.
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