The Skylab S-190B Earth Terrain Camera

The Skylab missions, completed in February 1974, included a wide variety of experiments in the fields of engineering, medicine, astronomy, and earth resources. The sensor of particular interest to the mapping and earth resources community was the S-190B Earth Terrain Camera (ETC). The ETC is a 460-mm focal-length frame camera with a 115by 115-mm format. It includes an image motion compensation system of an f/4 color-corrected lens. The predicted low contrast (1.6:1) ground resolution for color photographs is 14 m/1p or 70 1p/mm; the expected resolution for black-and-white photographs is 10 m/1p or 100 1p/mm. Considerable cloud-free imagery using color, color-infrared, and black-and-white films was obtained during the three Skylab missions. A map showing the ETC coverage is included in the paper. Preliminary analyses indicate that the photographs have the necessary resolution and geometric fidelity for preparing photomaps at 1:100,000 scale and possibly larger scales. Other investigators are evaluating the photographs for geologic, mineral resources, and land-use mapping, and for archeological, water resources, and recreational studies.