History of the Global Positioning System

by Caribou Betty

The history of the GPS was not an immediate Aha! or Eureka! moment, but a slow process over many years, taking bits and pieces from existing technology and adding to them.

  • Early 1940’s: Aircraft and naval vessels used a navigation system called LORAN, which stands for Long Range Navigation. Ships and aircraft would determine their position and speed by sending and receiving low frequency radio signals from stationary, land-based radio beacons up to 1,200 miles away. The use of LORAN was vital in determining a ships’ position in coastal waters.
  • 1955: Friedwardt Winterberg proposes in a paper to test Einstein’s General Theory of Relativity by using ultra accurate atomic clocks attached to man-made satellites orbiting the Earth. In 1955, the accuracy of atomic clocks was still a work in progress, and artificial or manufactured satellites did not yet exist. Some may have viewed Winterberg’s paper as a work in science fiction, but it laid the groundwork for the concept of the modern Global Positioning System.
  • 1957: The Soviet Union launches Sputnik, the first man-made satellite. Two physicists from the Applied Physics Laboratory (APL) in America used Sputnik’s radio transmissions and the Doppler Effect on those transmissions. Then they entered
    the data into a super-computer called UNIVAC to determine Sputnik’s exact location in space at any given time.
  • 1958: The deputy director of the APL, asked those same two physicists, William Guier and George Weiffenbach to invert the Sputnik location problem. In other words, if we know the location of a satellite in space, can we determine our location on Earth? The Polaris missiles were designed to be launched from submarines. But in order to hit the proper target, the submarine needed to know its own location, first. The result was the Transit navigational system.
  • 1960’s: Transit was the first navigation system in the world employing satellites. Used by the United States Navy, it was tested successfully in 1960. Five orbiting satellites were able to provide an accurate navigational fix once an hour.

The United States Air Force was simultaneously developing its own navigation system called MOSAIC (Mobile System for Accurate ICBM Control). MOSAIC was a radio-navigation system that was a three dimensional version of LORAN. The United States Air Force needed a navigational system that could keep up with the speed of their strategic bombers, and pinpoint accuracy for their nuclear arsenal of intercontinental ballistic missiles, (ICBM’s). By the late 1960’s the parallel U.S. Navy and Air Force programs began synthesizing into the idea of a single system.

Development of navigational systems in the 1960’s and 1970’s was very expensive, running into the billions of dollars. Even though improving the accuracy of navigational systems would benefit both the military and the civilians who utilize them, it was tough getting the research and development funding from the United States Congress. The “sell” to Congress and the American people, was the Cold War with Communism and the arms race with Soviet Union in particular. The threat of nuclear annihilation by the Soviet Union was enough to prompt Congress to fund newer, and improved navigation systems, and as a consequence, the birth of the Global Positioning System.

  • September 1973: A group of military officers at the Pentagon met and decided to combine the existing navigation systems such as Transit, Timation, 621B, etc. and refer to it as Defense Navigation Satellite System (DNSS). Later that same year DNSS was renamed Navstar. As more navigation satellites were being launched into space, a name was needed to describe the constellation of satellites orbiting the Earth in defense of the United States. The name created by the U. S. Department of Defense was Navstar-GPS.
  • 1978: The first of the Block-I GPS satellite was launched into orbit.
  • 1983: President Ronald Reagan issued a directive stating once the GPS system was fully developed, it would be available for civilian use as a common good. President Reagan did this as a response to a Korean Air Lines flight being shot down by the Soviet Union after the Korean Air passenger plane mistakenly flew into prohibited Soviet airspace. All 269 people aboard Korean Air, flight 007 were killed.
  • 1978 –1985: A total of eleven Block-I experimental satellites were put into orbit. Command & Control of the Block-I satellites was located in Colorado Springs, Colorado.
  • 1989-1994: Twenty-four Block-II GPS satellites were launched into space.
  • 1996: GPS satellites at that time sent two signals to receivers on or near Earth. The better quality of the two radio signals were reserved for use by the United States military. The inferior quality signal was referred to as Selective Availability. It was intentionally degraded for fear of enemies of the United States using the signal against us. President Clinton ordered the Selective Availability signal degradation to be turned off on May 1, 2000, based upon the recommendation of William Perry, U.S. Secretary of Defense.
  • 2000: Elimination of Selective Availability resulted in an immediate increase in the civilian radio signal accuracy, from 330 feet (100 meters) down to 66 feet (20 meters).
  • 2004: GPS is designated as a natural resource, owned by and operated by the United States Government. The National Space-Based Positioning, Navigation and Timing Executive Committee, which is chaired by the Deputy Secretary of Transportation and the Deputy Secretary of Defense, oversee the Global Positioning System. Committee members include Deputy Secretaries from the Departments of Commerce, State, Homeland Security, NASA and the Joints Chief of Staff.

2005 – Present: More modern satellites such as the Block IIR-M are launched, and the system continues with technological improvements and software upgrades.

The Russian government developed their own satellite navigation system called GLONASS, or Global Navigation Satellite System for use by their military. The Russian government made GLONASS available for civilian use in 2007. Other satellite navigation systems in various stages of development are the Chinese Compass, European Union’s Galileo, and India’s Regional Navigational Satellite System.

 

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