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Chapter 2: Global Positioning System

Information Technologies of Tomorrow
The evolution of information technologies has surpassed expectations for more than a half-century, and the next
50 years hold even greater promise. As researchers improve the intelligence capabilities of computers — particularly the ability to imitate the human process of reasoning — they will become an integral support in key decision processes. Decisions that include large numbers of factors involving natural and human processes, such as those on the military battlefield, will benefit from this capability. Soldiers will carry wireless devices with sensors that will “read” their surroundings — physical terrain, air quality, and compass direction — as well as the soldier’s own vital signs. A tiny transmitter will continuously relay the data back to a command post for analysis by larger computers as part of an ongoing, real-time decision-making process. As a result, commanders will have many more options available at an earlier stage, improving the chances for military success.

Closer to home, we need only consider that there are an estimated 20 billion microprocessors embedded in products around the world other than computers: our cars, watches, air conditioners, microwav e ovens, and VCRs. Soon we will live in “smart houses,” where we will plug dishwashers, clocks, stereos, and other household appliances into the Internet along with the electric power grid. At that point, instead of e-mailing home to ask the family to start dinner, we’ll be able to e-mail our kitchen appliances directly and order them to move the lasagna from the refrigerator to the oven and cook it at 375° for 45 minutes. The ma rvels of the Information Age are limited only by the imagination of future engineers and consumers.

What would it be worth if you could pinpoint your location anywhere on Earth, whenever you might need to know it, to an accuracy within a few hundred feet, usin g only an inexpensive handheld device? Would you answer this question differently if you were an airline pilot concerned that you had drifted off course? What if you were general manager of a trucking company trying to save time and money as you schedule the next two days’ pickups and deliveries for a fleet of 200 long-haul trucks? What if you were a weekend sailor sending a distress radio call because you’re in danger?

During the past decade, real people like those described — and thousands of others in a wide range of scenarios — have relied increasingly on the Global Positioning System (GPS) to calculate precise location. This ability, undreamed of before the age of satellites, has already saved countless lives and dollars for those who use it.
GPS consists of a constellation of 24 satellites that orbit the Earth every 12 hours, each emitt ing radio signals coded with data about its position and the time — accurate to within a billionth of a second. The satellites are deployed so that every point on Earth can always receive signals from at least four satellites. Receivers on Earth interpret these signals to pinpoint their own positions, anywhere on the globe, at any time of day or night, in any kind of weather.

A Breakthrough Based on Basic Research
The GPS we use today would not have been possible wit hout basic scientific research in atomic and molecular physics or advances in satellite, launch vehicle, and telecommunications technology. GPS technology actually grew out of pure physics research, starting in the 1930s, by scientists studying the nature of the universe and how to measure time exactly. By the 1950s, this research had developed extremely accurate atomic clocks, which would later be crucial in developing the concept of GPS. The adve nt of space satellites, with the Soviet Union’s launch of Sputnik I in 1957, allowed scientists and engineers to envision a system of navigation that would rely on satellite signals keyed to precise timekeeping. By 1973, the Department of Defense had approved the navigational concept that became GPS. Rockwell International began building the Navstar satellites that make up the GPS constellaion, each the size of a large automobile and weighing slightly less than a ton. In 1978, the first GPS satellite became operational; by 1993, the full 24-satellite system was in use. Technological advances in solid state electronics, microchips, and microwaves also contributed to the commercial success of GPS. In 1983, the first GPS receivers cost over $150,000 and weighed more than 100 pounds. Today, a handheld GPS receiver weighing less than a pound can be purchased for less than $100.

Most Americans first became aware of GPS when the U.S. military used it successfully in the 1991 Gulf War to target “smart” bombs and cruise missiles. In the deserts of Kuwait and Iraq, GPS gave U.S. forces a precise and reliable sense of where they were in unfamiliar territory. GPS again made headlines in 1999, when a U.S. F-16 went down in the northwestern part of Serbia during Operation Allied Force in the liberation of Kosovo. The Ame rican pilot was rescued by NATO forces and taken to safety within a matter of two hours, thanks to GPS technology.