The Transit-O series of satellites that closely followed the design of Transit 5C-1 were also called “Oscars” (Oscar is the phonetic alphabet for “O”, i. e., operational). They were also called NNS (Navy Navigation Satellite) or shortened NavSat.
Polar OrbitThe Program 206 satellite, carrying the KH-7 (Keyhole 7) camera system (codenamed Gambit-1), was the first successful high resolution space reconnaissance program. It was managed by NRO's Program A, the USAF-led segment of the National Reconnaissance Program managed from Los Angeles AFB in El Segundo, California.
Sun-Synchronous OrbitUS-A (Upravlenniye Sputnik Aktivny) were active radar satellites for ocean surveillance. The high power consumtion of the active radar required a nuclear reactor as power source. The satellites were known as RORSAT in the west. The US-AO series consisted of satellites, which tested all the system components but the nuclear reactor. They were battery powered.
Low Earth Orbit