Weather Satellites: ESSA I (TOS I)

ESSA I - Environmental Science Services Administration Satellite I

(TIROS Operational System I)

Launch date: February 3, 1966

Launch site: Cape Canaveral, Florida

Launch vehicle: Three-stage Delta

PROGRAM OBJECTIVE:

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 305 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 98 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.

ESSA I was able to view the weather of each area of the globe, photographing a given area at the exact same local time each day. ESSA I remained operational for 861 days until deactivated by NASA along with TIROS IX on June 12, 1968.

PARTICIPANTS:

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