A

David

Darling

TOS (TIROS Operational System)

TOS (TIROS Operational System) was the first operational United States polar-orbiting weather satellite system. It followed on from the experimental TIROS series, was managed by ESSA (Environmental Science Services Agency), and consisted of nine satellites launched between 1966 and 1969, and designated ESSA 1 to 9. It was succeeded by ITOS (Improved TIROS Operational System).