It may turn out to be the most far-reaching peacetime spinoff of the Cold War: a technology that brings military precision to civilian activities from taxi rides to wilderness treks, oil-spill cleanups to wildlife protection. The Global Positioning System uses radio signals beamed between satellites in orbit and receivers on Earth to "read" the location of people, places or things, moving or stationary. At the moment, though, anyone who's heard of GPS at all probably encountered it in luxury vehicles or rental cars boasting on-board navigation. By combining GPS and computer capabilities, scientists are creating powerful new tools for agriculture, transportation, industry, public works, recreation -- virtually any endeavor that requires knowing where something is or controlling its movement or placement.
Stanford scientists are in the thick of GPS-related research, and Professor Brad Parkinson, a guiding force in the field, says current applications of GPS are "only the beginning." Coming from Parkinson, the statement seems ironic, since GPS has been a huge part of his working life in the last 30 years. As an Air Force colonel with advanced degrees from MIT and Stanford, Parkinson led the Defense Department project that from 1972 to 1978 took GPS from concept to reality. The goal was a system that would help guide weapons to their targets and keep track of personnel and materiel. Now, Parkinson says, the biggest contribution of GPS may be "machine control," enabling no-hands navigation of commuter vehicles, heavy mining and construction machinery, even airplanes.
The professor's predictions aren't ivory-tower speculation. After he left the military in 1978, Parkinson, PhD '66, held top management positions at Rockwell International, Intermetrics Inc. and, in 1998, at commercial GPS pioneer Trimble Navigation. Since 1984, when he joined the department of aeronautics and astronautics at Stanford, Parkinson has built a research program devoted to nonmilitary applications for GPS, notably in the areas of aircraft, spacecraft and ground vehicle control. He is also program manager and co-principal investigator of NASA's $500 million Gravity Probe B experiment, which will use orbiting gyroscopes -- and GPS -- to test Einstein's General Theory of Relativity. His confidence in the technology springs from the Stanford team's successes as well as sales growth in the scant six years that GPS devices have been commercially available. "There are 3 to 4 million GPS receivers out there, and that comes close to doubling each year," he says in an interview at Gravity Probe B's campus quarters, where he has a second office.
At the heart of GPS is a man-made constellation of 24 satellites set in precise orbits 11,000 miles above Earth. These satellites carry atomic clocks and send out highly synchronized radio signals (see graphic, opposite) picked up by ground receivers, which can take various forms. (Wildlife managers have equipped elephants with GPS receivers mounted in neckpieces, while Casio brought out a GPS wristwatch prototype last year.) The receivers are programmed to "triangulate," using the locations of the satellites, the travel times of their signals and the speed of light to calculate distances. By measuring its distance from three different satellites, a receiver can determine and transmit its own position -- and by adding readings from a fourth satellite, it can compensate for distortions due to gravity and atmospheric conditions.
Early notions of such a system date back to 1957, when American scientists began to realize they could use radio signals from satellites like the Soviet Union's Sputnik to determine precise positions on earth. But throughout the 1960s, rivalry among the military branches and gaps in technology prevented the development of an integrated system. In 1972, Parkinson, then heading up the department of astronautics and computer science at the Air Force Academy, was tapped by Defense to attempt a miracle: head a joint program aimed at forcing the competing service arms to stop bickering and share ideas and resources.Parkinson used both engineering and diplomacy skills to push his team of more than 200 people forward on the $390 million mission to build the system, called Navstar GPS. "He carried the ball on the concept, got the funding, got the program established," says Glen Gibbons, editor of the magazine GPS World. Making such an unwieldy, ambitious project work meant integrating emerging satellite technology with sensors, precision clocks, orbital data, controls and complex calculations to offset errors. It also meant pulling together scientists and officials from the Air Force, Army, Navy, Marine Corps, Defense Mapping Agency, Coast Guard, Air Logistics Command and NATO.
According to Parkinson, the whole enterprise "came perilously close to cancellation." Defense authorities rejected the first GPS proposal presented to them in August 1973 on the grounds that it was really an Air Force creation, not a true joint effort. Parkinson pulled the project out of the fire. He gathered a dozen GPS program officials together and worked through the Labor Day weekend in a "neutral" room on the deserted fifth floor of the Pentagon. The result was a truly multiservice synthesis that gained speedy approval.
By 1978, Parkinson's team had launched and exhaustively tested a prototypical GPS system virtually identical to the one used today for applications as diverse as tracking icebergs and measuring the effects of tectonic shifts on Mount Everest. But it was to remain the exclusive domain of the military for almost two decades. It was a handheld GPS locator that led to the rescue of Air Force pilot Scott O'Grady, shot down over Bosnia in 1995. As recently as a year ago, the GPS satellite constellation was masterminding air strikes on Yugoslavia by America's arsenal of guided weapons.
Although it was obvious to Parkinson and others that GPS offered enormous commercial potential, the system was not fully available for civilian use until 1995 -- a decade after Parkinson hoped it would be. The government had spent $12 billion on the project, and still there were wrinkles. One was inaccuracy. In an effort to prevent enemies from using GPS to target the United States, the Defense Department built in an element of error (called "selective availability") to signals detectable by civilian GPS receivers. Left uncorrected, this margin of error could be as much as 150 meters, an unacceptable standard for many applications. But there is a way around it. So-called differential GPS (DGPS) offers accuracy to within a few centimeters in some cases. With DGPS, ground transmitters whose positions are known calculate the difference between their true locations and the locations specified by GPS satellites -- then broadcast corrections to receivers in their range.
Another obstacle to the marketing of GPS was prohibitive cost. But prices are dropping as miniaturization occurs, much as they did with computers. Today, GPS receivers can entail just a few integrated circuits, and a handheld device no bigger than a cell phone can be had for as little as $100. For $500, Casio plans to market what it calls the world's first wristwatch with built-in GPS to tell wearers where they are and -- when they input coordinates -- how far and in which direction their destination is.
Surveying was the first significant civil application of GPS. According to GPS manufacturer Trimble, today's receivers offer nearly instantaneous readings and require just one person, shaving the cost of a commercial survey from as much as $10,000 to less than $100. GPS has already taken off in industries requiring the dispatch of vehicles. FedEx uses it to track its planes and trucks, and thus its packages. As costs decrease, even relatively small operations such as San Jose's Outreach program, whose 160 vans carry disabled people to medical appointments every day, have adopted GPS to better organize pickups and drop-offs.
More applications suggest themselves all the time, says Trimble spokesman Mike Michelson. For example, archeologists and paleontologists have traditionally described the locations of their finds in relation to natural or man-made landmarks, which can be altered by weather or human intervention. GPS lets them record the location of a spot for future reference, regardless of whether a river changes course or a building gets demolished. Buoys equipped with GPS can monitor and communicate the movement of oil spills. Parkinson even sees the possibility of using differential GPS in land-mine clearance: robotic devices controlled by DGPS could clear the mines, and DGPS mapping could provide an accurate record of cleared areas. "It may be ironic," said Parkinson in a 1998 speech to the American Institute of Aeronautics and Astronautics, "that a system conceived for war could be used for such an important peacekeeping application."
GPS World editor Gibbons observes that GPS has been a success in specialty applications but "very disappointing to those who thought it would come along very quickly." Parkinson, however, is philosophical about lags between the advent of the technology and its widespread use. "The history of innovation being adapted by man, from electricity to computers, has been slower than expected," he says.
Some of Stanford's GPS-related research is finding a receptive market for commercial applications. On his office white board, Parkinson draws a typical path covered by a tractor operator in furrowing or bedding a field. "I can't imagine an activity that would be more mind-numbing," he says. If machine control could take over the driving, the operator could be there for emergencies but focus on other things, like examining the condition of the crop or fine-tuning pesticide or fertilizer treatments. GPS might one day guide the planting of certain crops in spiral patterns, allowing machinery to work the crop without having to stop, turn around and get back precisely on a plowing line, Parkinson says.
So it happened that anyone flying over a patch of farmland in central California two summers ago could have seen a perfectly formed, enormous S carved into the field. A team of Parkinson's graduate students had demonstrated that a driverless John Deere tractor, equipped with a GPS receiver linked to an automatic control system, could plow a field even in darkness or fog and achieve accuracy to within a few centimeters. In just 40 minutes, the tractor steadily plowed through John Deere's half-mile-square experimental field, executing perfect turns and reverses guided by a computer program. Mike O'Connor, PhD '98, one of the students, says his greatest satisfaction was that they could "turn a thesis into something that will really help farmers increase food production and lower pesticide use."
Farmers aren't so much looking to turn their backs on their tractors as to achieve greater efficiencies. Automation could reduce inconsistencies among drivers and the wasteful overlap of chemicals or seeds that results from imprecise tracks and awkward turns. At the farms that make up most of the American breadbasket, virtual flotillas of giant vehicles take to thousands of acres every day -- to plow, to spread chemicals and to harvest. What GPS may offer farmers is the capacity to reacquaint themselves with all the variations in their terrain and tailor what they plant and how they fertilize and water each part according to its individual conditions. Eventually, using GPS integrated with a computerized database, farmers could change treatments every few yards.
"As far as I'm concerned, GPS has already taken off," says Wayne Smith, project manager for sensors and control systems at John Deere Precision Farming. "We have 10,000 agricultural customers using GPS today."
Another Stanford project aims to help the nation's aircraft navigation. In 1994, Parkinson's students demonstrated a GPS-based control system, landing a Boeing 737 airplane on autopilot 110 times in succession, accurate to the centimeter. "We're hoping to adapt GPS to civil aviation needs," says Ray Swider of the Federal Aviation Administration, which funds the ongoing project. However, Swider points out that the FAA isn't ready to stake air safety to satellite signals that are still controlled solely by Defense.
Parkinson likes to call GPS "the ninth utility" -- after electricity, gas, telephone, water, sewer, garbage collection, TV and radio. He has wrestled with every aspect of the technology, from
research to marketing, and even took a sabbatical in 1998 to serve as chief executive of Trimble Navigation. In his nine months there, he backed the company away from the broad, consumer-licensing path that founder Charlie Trimble had pursued and refocused it on high-end uses like marine surveying and machine control, which he sees as the most promising market. At times, he says, that stint reminded him of missions he flew in Vietnam with a team developing an air-based weapons system designed to attack truck convoys. "The sniping at your reputation from investors on the Internet is somewhat akin to the enemy trying to kill you in battle," he says.
No matter what the investment analysts say, Parkinson insists that GPS technology will eventually become ubiquitous -- simply because it offers information on demand. "Knowing where you are, or where something is, is unifying," he says. For himself, Parkinson is glad to be where he is -- back on campus, out of the line of fire.
Joan O'C. Hamilton, '83, a Stanford contributing writer, is a columnist on high technology for Business Week. Additional reporting contributed by Ginny McCormick.
