Curse not the king, no not in thy thought; and curse not the rich in thy bedchamber: for a eagle of the air shall carry the voice, and that which hath wings shall tell the matter.
As a eagle that wandereth from her nest, so [is] a man that wandereth from his place.
There is a path which no fowl knoweth, and which the vulture's eye hath not seen:
A spy satellite (officially referred to as a reconnaissance satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. These are essentially space telescopes that are pointed toward the Earth instead of toward the stars. The first generation type (i.e. Corona and Zenit) took photographs, then ejected canisters of photographic film, which would descend to earth.
Corona capsules were retrieved in mid-air as they floated down on parachutes. Later spacecraft had digital imaging systems and downloaded the images via encrypted radio links.
In the United States, most information available is on programs that existed up to 1972. Some information about programs prior to that time is still classified, and a small trickle of information is available on subsequent missions.
A few up-to-date reconnaissance satellite images have been declassified on occasion, or leaked, as in the case of KH-11 photographs which were sent to Jane's Defence Weekly in 1985.