History of GPS – Part I
The U.S. Navy backed two programs, Transit and Timation, that served as predecessors for GPS. Transit, developed by the John Hopkins Applied Physics Laboratory under Dr. Richard Kirschner in 1959, was made up of seven low-altitude satellites and used Doppler distortion for positioning purposes. The system was slow, required long observation times, and had limited coverage, but Transit demonstrated the viability and reliability of a space-based system.
In 1964, the Naval Research Lab, directed by Roger Easton, began work on Timation, a Navy satellite system that advanced the development of high-stability clocks, time-transfer capability and three-dimensional navigation. The atomic clocks carried in these satellites improved predictions of satellite orbits and became prototypes for early GPS satellites.
In 1968, the U.S. Air Force joined the game with support for an aerospace study designated System 621B. The strength of this technology was a new type of satellite ranging signal based on pseudorandom noise. This allowed for greater accuracy of up to a hundredth of a mile.
With the proliferation of navigation systems research among the branches of the U.S. military, the Department of Defense decided in 1968 to create a steering committee called Navigation Satellite Executive Committee (NAVSEG) that involved the Navy, Air Force and Army. The committee commissioned a number of studies and promoted collaboration and debate among the various satellite navigation groups. In 1973, the Deputy Secretary of Defense proposed a joint program office (JPO) to consolidate research efforts into one comprehensive concept. The Air Force was designated as the program manager, lead by Colonel Brad Parkinson.
It was under the JPO that the initial concept of the NAVSTAR GPS system was born, and like pieces of a puzzle, it incorporated the best all the available satellite navigation systems. The final plan combined signal structure and frequencies from the Air Force’s 621B with satellites orbits from the Navy’s Timation. In 1973, the Department of Defense approved the first phase in the creation of the NAVSTAR.
Between 1978 and 1985, the U.S. launched eleven of the first-generation of GPS satellites, designated as Block I. In addition to positioning and timing equipment, the U.S. government also equipped these satellites with nuclear detonation sensors starting in 1980. These devices enabled the detection of nuclear weapon explosions and assessment of nuclear attacks. GPS satellites continue to play a dual role in nuclear detection today and are instrumental in ensuring compliance with nuclear non-proliferation treaties.
With the basic building blocks of GPS in place, it was ripe for innovative applications that continue to today. Next week, read about how GPS made transition from a fledgling military concept to a versatile and widely used technology.
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Tags: GPS Tracking, History of GPS, LORAN, NAVSTAR, Richard Kirschner, Roger Easton
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April 30th, 2010 at 8:53 am
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