This device, made by the Advanced Technology Laboratories, was mounted on the left-hand side of the exterior of the Gemini space capsule. It was used, in conjunction with an electronics package, to sense the position of the Earth's horizon relative to the capsule's position in orbit. It contained a pivoting mirror, lens, and infra-red sensor to locate the horizon. The location of the horizon relative to the spacecraft was used to align the spacecraft or its inertial guidance system.
This specimen was probably not flown but used for test purposes.
Transferred to the National Air and Space Museum from NASA in 1977.
Transferred from the National Aeronautics and Space Administration