A U.S. reconnaissance satellite system developed by the Lockheed Corporation beginning in the 1950s. Its infrared sensors and a telescope were designed to detect the hot exhaust of enemy missiles being launched and to radio a warning to Earth stations allowing the U.S. Air Force to scramble its bombers before the enemy warheads struck. The system was renamed the Defense Support Program in the 1960s.
See the Introduction, Abbreviations and Pronunciation for further details.