United States Updates Global Positioning System Technology

THE EARLY DAYS OF GPS

Like the Internet, which arose from a 1969 research project of the U.S. Defense Department, GPS began as a military research project in the 1960s and 1970s. The idea was to fly atomic clocks on satellites and use the data for navigation.

The system has several components: a constellation of 24 NAVSTAR satellites (operated by the U.S. Air Force) in Earth orbit with atomic clocks aboard, ground stations that control the system, five on-orbit spare satellites and receivers for users.

GPS satellite launches started in 1978, and second-generation satellites were launched beginning in 1989. The system became fully operational in 1995, with a signal for military users and a less-accurate signal for civilians, but the commercial market had begun to open up more than a decade earlier.

In 1983, Soviet jet interceptors shot down a Korean Air civilian airliner carrying 269 passengers that had mistakenly entered Soviet airspace.

Because crew access to better navigational tools might have prevented the disaster, President Ronald Reagan issued a directive guaranteeing that GPS signals would be available at no charge to the world when the system became operational. The commercial market has grown steadily ever since.

In 2004, President Bush issued an updated policy that keeps civilian GPS free of direct user fees.