GPS - The early history

In October 1957 the U.S.S.R launched the Sputnik the first artificail satellite to orbit the Earth. Two junior physicists at John Hopkins, William Guier and George Weiffenbach, decided to listen in on the satellite using a supersensitive shortwave receiver. As it passed overhead they noticed a change in the frequency due to the doppler effect. Guier came up with a theory that the satellite could be tracked by analyzing the change of the slope of the frequency shift. They proved the theory by tracking Sputnik and later on the Explorer I satellite, the first satellite launched by the United States.

In March 1958 Frank McClure the head of the Advanced Physics Laboratory Research Center questioned Guier and Weffenbach about their findings. McClure later came up with the idea of reversing the idea so it be used by ships for navigation. McClure teamed up with Richard Kershner and drew up plans for a navigation system using satellites. It was later adopted and prefected for the United States Polaris Submarine program. The system was called Transit and was in use for over 30 years until 1996. It was not only used by Navy, but also by merchant marine ships, civilians and was even used to position oil rigs.

The work of these great physicists paved the way for the current GPS system that powers our Magellans and Garmins that we use for geocaching.