Each Viking Lander was equipped with two identical cameras that, unlike conventional cameras, did not use film. Instead, a moveable mirror scanned a vertical segment of the martian scene, and photodetectors recorded the amount of light reflected into the camera. A complete picture, or "image" of the surface was made by completing a vertical scan, and then rotating the camera slightly for the next scan.
This back-up camera was transferred from NASA's Jet Propulsion Laboratory to the Museum in 1981.
Transferred from NASA's Jet Propulsion Laboratory