Short answers, pulled from the story.
The United States Air Force officially ordered the development of an advanced reconnaissance satellite on the 16th of March 1955. This directive aimed to provide continuous surveillance of preselected areas on Earth.
The CORONA project ended in 1972 after decades of operation. It became a priority to photograph denied areas that were previously inaccessible during its active years.
The Zenit satellite series launched from 1961 until 1994 when its final flight served as a test payload. The Soviet Union authorized a similar program through a decree for Sputnik before this design evolved into Vostok and Zenit.
A $1-billion high-powered spy satellite launched from California's Vandenberg Air Force Base on the 28th of August 2013. That vehicle snapped pictures detailed enough to distinguish the make and model of an automobile hundreds of miles below.
Intelligence agencies gained certainty that no new ICBM complexes had been established in the USSR during the past year in 1968. This confirmation came directly from satellite photography rather than human intelligence sources.