US-PM (US-PU)

US-PM (Upravlenniye Sputnik Passivny Modifikirovanny) (also reported as US-PU) was a solar powered improved EORSAT (Electronic Ocean Reconnaisance Satellite). It used an passive ELINT devices to track naval vessels from space by registering their electronic emmissions.

US-PM was a modified version of the US-P and replaced both the US-P and the nuclear US-A satellites.

It shared the same US bus with its precedessors, which provided maneuvering capabilities to the spacecraft.

The US-PM 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.