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The first was a six-camera system, identified as S-190A, designed 
for further experimentation in the multispectral approach to identi- 
fication of terrain features. There are six identical cameras of 
152 mm focal length with a 58 x 58 mm format on 70 mm roll film. 
Four of the cameras used black and white film and suitable filters 
to record the green, red, and two near-infrared spectral bands. The 
fifth camera carried full-color film, and the sixth carried color 
infrared. From the nominal altitude of 435 km the image scale is 
1:2,800,000, a little larger than that of the original Landsat film. 
The resolution varies from about 40 m maximum with the black and 
white film to 100 m minimum with the color infrared. The S-190A 
photography proved useful for multicolor reproduction at scales up 
to 1:250,000 and for black/white reproduction at 1:100,000 scale. 
But detail was still inadequate for consistent revision of cultural 
features on maps (16). 
The second camera system, identified as S-190B, with 460 mm focal 
length produced an image scale of 1:950,000 on a format of 115 x 115 mm. 
The maximum ground resolution obtained was 10 m on high resolution black/ 
white film decreasing to 45 meters on color infrared film (17). - Tests 
have indicated that the color photographs can be enlarged to about 
1:100,000 scale before image quality decreased beyond the limit of 
acceptability.  Planimetric map revision at scale up to 1:50,000 has 
been accomplished with reasonable completeness (18, 19, 20). 
The third imaging system on Skylab was the 5-192 13 channel 
multispectral scanner. It provided about the same resolution as 
Landsat. The large number of spectral bands permitted a wide variety 
of multispectral experiments ‘at terrain classification, but the 
major cartographic conclusion was that the 1.55 to 1.75 um band 
provided superior delineatidn and separation of water, culture, and 
vegetation (21). 
An overall conclusion from the Skylab experience is that a multi- 
purpose manned mission is a completely inefficient way to collect 
image data. Too many other demands are made on the crew's time, 
and the spacecraft is enormously complicated by the life support and 
crew safety subsystems. The spacecraft is forced into relatively 
low inclination orbits and its lifetime is necessarily limited. These 
shortcomings are graphically illustrated by the coverage diagrams of 
the Skylab sensors. The major advantages of the Skylab experiments 
were to demonstrate the scale and resolution required to produce 
medium and large scale maps from space photographs, and to test the 
international reaction to the open distribution of relatively high 
quality space photography. 
Lunar Photography 
  
Apollo 17, the last of the lunar exploration missions, splashed 
down in the Pacific Ocean in December of 1972. The last three Apollo