This is an unflown Series I infrared sensor, built by Aerojet ElectroSystems for use in U.S. Air Force Missile Defense Alarm System (MIDAS) satellites. These spacecraft were designed to detect and track the hot exhaust gases of Soviet missiles at launch and thereby provide up to thirty minutes warning of an attack. Series I sensors were built for the first two low-altitude MIDAS test demonstration flights in 1960, but both spacecraft failed to reach proper orbit. MIDAS was cancelled in the late 1960s, and the more advanced Defense Support Program early warning satellites were launched beginning in 1970. This artifact was donated to NASM by Aerojet ElectroSystems in 1992.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.