The Navy Navigation Satellite System (TRANSIT)

The present article provides an update on the status of the Navy Navigation Satellite System (Transit). It is pointed out, that, in 1958, research scientists at the Applied Physics Laboratory (APL) solved the orbit of the first Russian satellite, Sputnik-1, by analysis of the observed Doppler shift of its transmitted signal. This result led immediately to the concept of satellite navigation and the development of the U.S. Navy Navigation Satellite System (Transit) by APL, to provide position fixes for the Fleet Ballistic Missile Weapon System submarines. At the present time, 26 years after its conception, the system is mature. Beginning with the release of the system to industry in July 1967, it has been used by military and civilian navigators for position fixing and for surveying. Attention is given to system reliability, developments regarding the constellation of satellites, satellite configurations, the users of the Transit system, and plans to continue operation of Transit until 1994.