Weather Satellites: ESSA III

ESSA III - Environmental Science Services Administration Satellite III

Launch date: October 2, 1966

Launch site: Vandenberg AFB, California

Launch vehicle: Thrust augmented Three-stage Delta

PROGRAM OBJECTIVE:

To replace ESSA I and provide cloud cover photography to the US's National Meteorological Center for the purpose of preparing operational weather analyses and forecasts.

SATELLITE DESCRIPTION:

The spacecraft was an 18-sided polygon, 42 inches in diameter, 22 inches high and weighed 320 pounds. The craft was made of aluminum alloy and stainless steel then covered with 9100 solar cells. The solar cells served to charge the 63 nickel-cadmium batteries.

The two cameras were mounted 180 degrees opposite each other along the side of the cylindrical craft. The "cartwheel" configuration of the TIROS IX was selected as the orbital configuration of the operational series of ESSA satellites. Therefore, a camera could be pointed at some point on Earth every time the satellite rotated along its axis. The spacecraft operating system was the same as on the TIROS IX. The craft was placed in its planned sun-synchronous 101 degree inclination retrograde orbit. The satellite spin axis was rotated using the magnetic attitude control system into an alignment perpendicular to the orbital plane and tangent to the EarthÕs surface. The ESSA III system transmitted images covering 2000 mile square areas with 2 mile resolution from every location once per day.

ESSA III remained operational for 736 days until deactivated by NASA on December 2, 1968.

PARTICIPANTS:

NASA, ESSA, RCA, US Weather Bureau, NMC.