KH-10
Starting in 1965 a large optical system was added to the spacecraft for military reconnaissance. This camera system was codenamed "Dorian" and given the designation KH-10. The project was canceled on June 10, 1969 before any operational flights occurred.
The KH-10 intended for the MOL program was succeeded by the unmanned KH-11 Kennan, which launched in 1976 as the Soviet Union was winding down its manned space reconnaissance program. The KH-11 achieved the goal of 3-inch (76 mm) imaging resolution and introduced video transmission of images back to Earth.
Read more about this topic: Manned Orbiting Laboratory