This telescope tube and aiming device for backup infra-red (IR) spectrometer for Skylab was part of the Earth resources evaluation experiment. This experiment was designed to provide data for calibrating and evaluating spectrometer data itself for the study of earth resources. The central part of this instrument contains a filter wheel, which allowed measurements to be made of light reflected from the earth's surface at four different wavelengths ranging from the visible to the infrared regions. The instrument had a field of view of approximately one-quarter mile on the earth;s surface. It was pointed and tracked manually by an astronaut at the lowest point of the Skylab's orbit. The viewfinder was manufactured by the Martin Marietta Aerospace Group for NASA.
It was transferred to NASM from NASA's Johnson Space Flight Center in 1979.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.