In the 1970s NASA inaugurated the Landsat series of satellites to study the Earth from space. The program demonstrated the practical benefits of research from satellites: for the first time the Earth's natural resources--land, water, and vegetation--could be mapped and studied continuously and on a global basis. Landsat 1 (originally called the Earth Resources Technology Satellite) was launched in 1972.
One of the main instruments used in studying the earth from space on Landsats 1, 2, and 3 was a Return Beam Vidicon (RBV) camera. Essentially a television camera, the RBV provided black and white images of the Earth and also was used to calibrate and intrepret images from a companion instrument on Landsat--a multi-spectral scanner (MSS).
The NASM artifact is a backup for the RBV that flew on Landsat 3, which was launched in 1978.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.