President Clinton Removes Global Positioning System Accuracy Constraints

By Keith Cowing
May 1, 2000
Filed under ,

GPS Block II satelliteAfter several years of study, President Clinton has removed the prohibition against the use of the high accuracy location capabilities of the Global Positioning System. Once reserved only for military uses such as cruise missile navigation, this enhanced capability is certain to result in a wide array of new consumer applications from rental car navigation to pinpointing 911 callers. GPS is an example of the immense potential of space-based systems to provide commercial and societal benefits on Earth.

The GPS system (also known as NAVSTAR) is composed of a collection of satellites orbiting 11,000 (20,200 km) miles above Earth in circular orbits inclined at 55 degrees. The satellites are arrayed in 6 orbital planes with 4 satellites orbiting in each plane. The system was inaugurated with the launch of the first GPS satellite in 1978. As the operational satellites were launched, it has grown to a constellation of 24 satellites.

GPS receivers on Earth use triangulation to determine a user’s location on the Earth’s surface. Up until today’s announcement, the accuracy available to someone using a civilian GPS receiver with C/A code is around 100 meters. Now the public will have access to the same accuracy heretofore only available to the US military which allows one to determine their location to within approximately 20 meters anywhere on (or above) Earth. Expect to see Space Shuttles using GPS very soon as they approach and dock with the International Space Station.

Meanwhile, not to be outdone, there is another positioning satellite system which may give the GPS some competition – Russia’s GLONASS system. With a commercialized Mir now taunting ISS ….

° Statement by the President Regarding the United States’ Decision to Stop Degrading Global Positioning System Accuracy, The White House

° President Clinton: Improving the Civilian Global Positioning System, The White House

° Interagency GPS Executive Board

° Fact Sheet: US Global Positioning System Policy, 29 March 1996

° GPS Primer, The Aerospace Corporation

° USNO NAVSTAR Global Positioning System, US Naval Observatory

° Global Positioning System, NASA JPL

° Global Positioning System, University of Michigan

° GLONASS Information Center

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.