ability to introduce errors at any time into the civilian signal to reduce its accuracy to about 300 feet.

Twenty-four Navstar satellites—each the size of a large automobile and weighing some 1,900 pounds —circle the earth in 11,000-mile-high orbits. The satellite system, built by Rockwell International and operated by the U.S. Air Force, was completed in 1993, 20 years after it was first conceived in the Pentagon. (Lockheed Martin Astro Space)

In March 1996, the White House announced that the highest level of GPS accuracy will be made available to everyone, and the practice of degrading civil GPS signals will be phased out within a decade. The White House also reaffirmed the federal government's commitment to providing GPS services for peaceful civil, commercial, and scientific use on a worldwide basis and free of charge.

The future of GPS appears to be virtually unlimited; technological fantasies abound. The system provides a novel, unique, and instantly available address for every square yard on the surface of the planet —a new international standard for locations and distances. To the computers of the world, at least, our locations may be defined not by a street address, a city, and a state, but by a longitude and a latitude. With the GPS location of services stored with phone numbers in computerized “yellow pages,” the search for a local restaurant or the nearest gas station in any city, town, or suburb will be completed in an instant. With GPS, the world has been given a technology of unbounded promise, born in the laboratories of scientists who were motivated by their own curiosity to probe the nature of the universe and our world, and built on the fruits of publically supported basic research.

In March 1996, the White House announced that the highest level of GPS accuracy will be made available to everyone, and the practice of degrading civil GPS signals will be phased out within a decade. The White House also reaffirmed the federal government's commitment to providing GPS services for peaceful civil, commercial, and scientific use on a worldwide basis and free of charge.