Satellites can be classified by their function since they are launched into space to do a specific job. A reconnaissance satellite is an artificial satellite launched by a country to provide intelligence information on the military activities of foreign countries. It is also known as an intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. These are robotic observational platforms that orbit the Earth in order to image its surface and to record radio signals for military and political purposes.
A reconnaissance satellite is a low-orbiting satellite that collects information about civilian and military installations in other countries using an optical or radar system.
The first generation type (i.e., Corona and Zenit) took photographs and then ejected canisters of photographic film which would descend back down into Earth’s atmosphere. Communications satellites are artificial satellites that relay receives signals from an earth station and then retransmit the signal to other earth stations. 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. They commonly move in a geostationary orbit. A remote sensing instrument collects information about an object.
Hundreds of spy satellites have been launched since 1960 when the U.S. lofted it’s first. In the United States, most information available is on programs that existed up to 1972, as this information has been declassified due to its age. The four basic types of spy satellite are:
(1) photoreconnaissance systems that take pictures in visible and infrared light,
(2) infrared telescopes designed to detect missile launches,
(3) radars that image sea or land even through cloud cover and in darkness, and
(4) signals intelligence (SIGINT) satellites (also termed “ferrets”), which are optimized either for characterizing ground-based radar systems or for eavesdropping on communications.
Specifically, a spy satellite is a satellite with sensors to detect nuclear explosions. Some information about programs prior to that time is still classified, and a small amount of information is available on subsequent missions. To use spy satellites in such a manner is often referred to in treaties as national technical means of verification.
A reconnaissance satellite a military satellite designed to carry out photographic surveillance, gather electronic intelligence, detect nuclear explosions, or provide early warning of strategic-missile launchings. 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 1984. The primary purpose of most spy satellites is to monitor visible ground activity.