Transit had its inception just days after the launch of Sputnik on October 4, 1957. Two scientists at The Johns Hopkins University Applied Physics Laboratory (APL) -- George Weiffenbach and William Guier -- were able to determine Sputnik's orbit by analyzing the Doppler shift of its radio signals during a single pass. Frank McClure, then chairman of APL's Research Center, went a step further by suggesting that if the satellite's position were known and predictable, the Doppler shift could be used to locate a receiver on Earth; in other words, one could navigate by satellite.
With early funding from the Advanced Research Projects Agency (ARPA), the development of the system began at APL in 1958 under the leadership of Richard Kershner. The Navy assumed responsibility for the system in 1960, and by the end of 1964 APL had designed, built, and launched 15 navigation satellites and eight related research satellites; established a worldwide network of tracking stations; determined the Earth's gravity field with enough accuracy to permit a satellite's orbit to be predicted for more than 12 hours; developed the system software; measured the satellite's environment; and overseen the development of operational ground stations and shipboard equipment.
The first prototype satellite was launched in September 1959, and the system entered Naval service in 1964. The system provided passive, accurate, reliable, all-weather global navigation for Navy submarines and surface ships. The last Transit satellite launch was in August 1988.
Learn more at: sd-www.jhuapl.edu/Transit/
Copyright 1996 The Johns Hopkins University Applied Physics Laboratory