 Transit (satellite)

The Transit system, also known as NAVSAT or NNSS (for "Navy Navigation Satellite System"), was the first satellite navigation system to be used operationally.The system was primarily used by the U.S. Navy to provide accurate location information to its Polaris ballistic missile submarines, and it was also used as a navigation system by the Navy's surface ships, as well as for hydrographic survey and geodetic surveying.