South Korea put its second domestically made spy satellite into orbit recently, after it launched from an American space centre on a SpaceX Falcon 9 rocket.
In addition to traditional imagery, modern spy satellites may collect other types of data, such as synthetic aperture radar (SAR) images, signals intelligence (SIGINT), or electronic intelligence (ELINT).
Spy satellites employ countermeasures to mitigate jamming or spoofing attempts aimed at disrupting or intercepting their signals.
Spy satellites are placed in specific orbits to optimize their surveillance capabilities. These orbits can vary, but they often involve low Earth orbits (LEO) or geosynchronous orbits (GEO).
India, which is in a growing rivalry faces with China, has launched a series of radar imaging satellites (RISAT).