Aerojet ElectroSystems built this Series III infrared sensor payload for use in Missile Defense Alarm System (MIDAS) satellites, one part of a U.S. Air Force program beginning in the late 1950s to provide early warning of a Soviet missile attack. The Series III was designed to detect and track the hot exhaust gases of missiles at launch and during the boost phase. This data would be relayed to ground stations to give up to 30 minutes warning of an attack. A Series III in May 1963 became the first space-based sensor to detect successfully a missile launch. MIDAS was cancelled in the late 1960s, and the more advanced Defense Support Program early warning satellites were launched beginning in 1970. The manufacturer donated this unflown artifact to NASM in 1969.
