Weather Satellites: ATS III

ATS III - Applications Technology Satellite III

Launch date: November 5, 1967

Launch site: Cape Canaveral, Florida

Launch vehicle: Atlas Agena D

PROGRAM OBJECTIVE:

Further development of the experimental geostationary techniques of satellite orbit and motion, measure the orbital environment at 23,000 miles above the earth's surface, and to transmit meteorological information (imagery and data) to surface ground stations.

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.

ATS III was placed in a transfer orbit directly over the equator over 45 degrees west (ATS was over the eastern Pacific at this time). The transfer orbit meant that the satellite would drift slowly westward with time. The satellite eventually reached 95 degrees west where it was deactivated with ATS I on December 1, 1978. Of the satellite's eleven year life span, useful data was received for the first eight (1967-1975).

PARTICIPANTS:

NASA, Hughes, AVCO, Control Data Corp., General Dynamics, ITT, Raytheon, RCA, Sylvania, Westinghouse