SPACECRAFT DESCRIPTION:
The spacecraft was slightly larger than ATS I. ATS III was a
cylinder 60 inches in diameter, 72 inches high and weighed 805
pounds. A phased array of eight whip antennas extended from the
top, and a phased array of eight VHF antennas extended from the
base. The sides of the cylinder were covered by 23,870 solar cells
which, along with nicad batteries, provided the power for the
craft.
Three meteorological experiments were on board. One was a spin scan
cloud camera which provided continuous, full-disk hemispheric
images of the sun-lit Earth every half hour. This camera was
modified to produce color images. The spinning motion of the
satellite generated line scans with a spatial resolution of 3.2
kilometers. This process took approximately twenty minutes for the
full image, and then ten minutes to reset the camera for a new
image. The second experiment was an Image Dissector Camera which
scanned the full-disk electronically rather than mechanically. The
third experiment was Weather Facsimile (WEFAX), a data relay and
re-transmission instrument. This instrument relayed data from the
central ESSA data processing facility to APT ground stations
located around the western hemisphere. In addition, images from the
spin scan camera were also transmitted over WEFAX to APT
stations.