.title
Wide Field/Planetary Camera

.synonym
Wide Field Planetary Camera

.description
A camera that can take photographs either in "wide-field" or "planetary"
mode.  The resulting images are transmitted by radio to Earth.
.contents

.para
     This instrument .~ (fig. 8)~ can operate in one of two modes.  In 
"wide field" mode, its focal ratio of f/12.9 will permit examination of
large areas of space, leading to more accurate plotting of the spatial
relationships of distant objects such as galaxies and quasars.
High-resolution images of planets within our solar system can be obtained
by the planetary camera, which has a focal ratio of f/30.


.para
     Images telemetered to Earth by radio will be far better than
pictures produced by ground-based cameras.  Pictures of Jupiter, for
example, will be comparable to those taken by the two Voyager spacecraft
in 1979.  Pictures of more distant planets will not be as clear as those
taken by Voyager, but will be far superior to those taken from Earth.


.para
     The camera consists of a complex system of instruments and mirrors.
The field of view is split by a .~ pyramidal mirror~ into four separate
areas which are focused onto four .~ charge-coupled devices~.  These
devices have been designed to receive light of low intensity at very high
resolution. A portion of the image is received on each target plate and
is subdivided into 640,000 picture elements (pixels).  The light
intensities of each pixel are transmitted to Earth via telemetry signals
for assembly into images for study.  Images can be created from
different spectral bands by directing the light through any one of 50 
spectral filters within the camera.