ESSA 3 was a sun-synchronous operational meteorological satellite designed to provide real-time earth cloudcover TV pictures to properly equipped ground receiving stations for use in weather analysis and forecasting.
The satellite carried two redundant Advanced Vidicon Camera System (AVCS) cameras were mounted on opposite sides of the spacecraft, with their optical axes perpendicular to the spin axis.

ESSA 3 performed normally until January 20, 1967, when the radiometer experiment failed. The first AVCS camera failed on September 29, 1967, the remaining camera failed on October 9, 1968, and the satellite was deactivated on December 2, 1968.