The TRANSIT system, also known as NAVSAT (for Navy Navigation Satellite System), was the first satellite navigation system to be used operationally. The system was primarily used by the US Navy to provide accurate location information to ballistic missile submarines, and was also used as a general navigation system by the Navy, as well as hydrographic and geodetic surveying.
Development of the system began in 1958, and a prototype satellite, Transit 1A, was launched in September 1959. That satellite failed to reach orbit. A second satellite, Transit 1B, was successfully launched 1960-04-13 by a Thor-Ablestar rocket. The first successful tests of the system were made in 1960, and the system entered Naval service in 1964.