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missions 15, 16, and 17 carried the only truly photogrammetric mapping
system which NASA has yet placed in space. These three missions
photographed about 25 percent of the total lunar surface.
In one section of the Service Module were carried the Mapping
Camera System and the Panoramic Camera System. The Mapping Camera
System contained a 75 mm focal length 115 x 115 mm format metric camera
which resolved about 20m on the lunar surface from the nominal 110 km
orbit. There was also a stellar camera for determining camera attitude,
a laser altimeter and a precise clock. The panoramic camera employed
folded optics and moving film to fit a focal length of 610 mm and a
sweep angle of 108 degrees in a very compact system. In order to
provide stereoscopic coverage the camera tilted 12 1/2 degrees forward
for one picture and 12 1/2 degrees aft for the following picture. In
order to remove the distortions inherent in panoramic photographs
an optical rectifier was built to transform the photographs into
equivalent frame pictures.
From the mapping camera photographs a control net has been
established by analytical triangulation. The Defense Mapping Agency
computed each mission separately (22), and a simultaneous solution
of 1244 frames was computed in a joint effort of the U.S. Geological
Survey and the National Geodetic Survey (23). Based on this control
net, orthophotomaps at 1:250,000 scale with 50 and 100 m contours are
being compiled. From the panoramic photographs contoured orthophoto-
maps at scales as large as 1:25,000 are being prepared for the landing
sites and other areas of special scientific interest.
The unmanned lunar probes Zond 6 (1968) and Zond 8 (1970) launched
by the USSR carried cameras of 302 mm and 400 mm focal length respectively
with format of 130 x 180 mm.. The original film was returned to
Earth from circumlunar orbit. Based upon these high quality photo-
graphs the Soviets have produced maps at scale 1:1,000,000 with con-
tour interval 500 meters for sites of particular scientific interest
and general area maps at scale 1:2,000,000 (24).
Mars Mapping
Mariner 9 launched in May 1971 carried two television cameras
of 50 mm and 500 mm focal length into orbit around Mars (25). A
total of 7,329 pictures provided complete coverage of the planet (26).
The image processing of the Mariner 9 pictures is completely digital.
A variety of computer algorithms have been developed to apply photo-
metri; and geometric corrections, and to mosaic the pictures to
selected map projections (27). A control network with a planimetric
accuracy of about 10 km has been computed from the pictures (28),
rectified mosaics have been assembled, and airbrush renderings have
been produced to prepare map series at scales 1:25,000,000; 1:5,000,000;
1:1,000,000; and 1:250,000 (29).
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