Inventors Hall of Fame
DR. BRADFORD W. PARKINSON
Dr. Bradford W. Parkinson is widely recognized as the father of the Global Positioning System (GPS), the satellite-based, worldwide navigation system. He has been recognized as a Professor Emeritus of Aeronautics and Astronautics at Stanford University, has written two books on GPS, and has received eight patents.
As a young Air Force colonel in the 1970s, he was the person most responsible for synthesizing elements of competing navigational systems into a single, viable concept. His education, experience, and personality made him particularly well-qualified to lead the multi-service and civilian joint task force that created GPS.
Parkinson was born in Madison, Wisconsin on February 16, 1935, but grew up in Minneapolis. He credits his math teacher at the Breck School in Golden Valley for inspiring in him an early love of math and science. After high school Parkinson attended the Naval Academy, where he excelled in math and science and developed an interest in controls engineering. His electrical engineering professor, an Air Force officer serving as an exchange officer at the Naval Academy, suggested the educational opportunities in the Air Force were better, so Parkinson joined the Air Force after graduation.
While serving in the Air Force, Parkinson studied aeronautics and astronautics at the Massachusetts Institute of Technology (MIT) and controls engineering at Stanford University. His doctoral dissertation was on a version of a gyroscope.
He served as a guidance analyst at the Central Inertial Guidance Test Facility at Holloman Air Force Base, where his assignments included analysis of inertial guidance for ICBM's and inertial navigation systems in airplanes.
For a time he headed the Department of Astronautics and Computer Science at the Air Force Academy, where he was involved in the introduction of the AC-130 gunships into combat over Laos. The gunships had a sophisticated digital control system for cannons and howitzers. As a pilot during duty in Vietnam in 1969, he flew 26 combat missions. Parkinson says he gained a keen appreciation for what it was like to get shot at and the need for precision weapon delivery.
After his tour of duty in Vietnam, Parkinson was reassigned to the Space and Missile Systems Organization as the chief engineer, where his work was focused on advanced ballistic missile technology and maneuvering reentry vehicles controlled by inertial guidance systems.
. After 16 years of military service, Parkinson had acquired an in-depth understanding of inertial guidance navigation systems, advanced ballistic missile technology, and astrodynamics, and a familiarity with satellites.
Parkinson's work on the GPS program began in late 1972, when he was assigned to a U.S. Air Force program established to create a global navigation system using satellites. Initially the program was called 621B, a joint activity of the Air Force and The Aerospace Corporation.
Parkinson quickly realized the project's potential and says he became a zealot for GPS, "And zealots are not easily discouraged." He soon became manager, and later the director. During development of GPS he worked closely with Dr. Ivan Getting, the first president of The Aerospace Corporation.
Although now widely used in everyday life, the GPS program came perilously close to cancellation in 1973. In August, following Parkinson's presentation of the 621B program to the Defense Systems Acquisition Review Council, the program was cancelled.
The existence of competing programs and some technical issues doomed the 621B program at that time. 621B was based on the concept of generating the signal on the ground, sending it up to the satellite, and then retransmitting it. It had some vulnerabilities and inaccuracies, because with all the transfers of signals, maintaining precise time to an accuracy of nanoseconds would have been very difficult.
When the Soviet Union launched the first satellite, Sputnik 1, in 1957, two American physicists, William Guier and George Weiffenbach, at Johns Hopkins's Applied Physics Laboratory, decided to monitor Sputnik's radio transmissions. Within hours they realized that, because of the Doppler effect, they could pinpoint where the satellite was along its orbit.
The Navy's SPO (System Program Office) developed Transit, which put a code generator on the low-altitude satellites, and developed software to predict orbits. Another major program, Timation, led by Dr. Roger Easton at the Naval Research Laboratory, focused on orbiting clocks broadcasting an accurate time reference for use as a ranging signal to the receiver on the ground – used to measure the distance to the satellite – and navigation messages used to precisely calculate the position of each satellite in orbit.
In 1964, the U.S. Army orbited its first Sequential Collation of Range (SECOR) satellite used for geodetic surveying. The SECOR system included three ground-based transmitters from known locations that would send signals to the satellite transponder in orbit. A fourth ground-based station, at an undetermined position, could then use those signals to fix its location precisely.
When 621B was cancelled, it was suggested that Parkinson reconstitute the project using the best concepts of other programs and do so as quickly as possible. Working over the Labor Day weekend, Parkinson and his team of twelve talented engineers synthesized GPS out of the 621B, Transit, Timation and Secor programs, arrived at the basic concept of GPS, and drafted a seven-page paper describing GPS as it is known today. The concept is based on time and the known position of specialized satellites.
The revised plan called for a network of satellites, each broadcasting on the same signal frequency and outfitted with incredibly precise atomic clocks. A receiver on the ground would pick up the signals, the location of the satellite and the exact time the signal was broadcast to precisely determine its location on Earth.
The team then prepared detailed descriptive materials, and over the next three months Parkinson presented the GPS concept to every significant office in the Pentagon and the Department of Defense. The previous resistance no longer had a technical basis. In December, 1973, the team received the necessary approvals and funding to proceed.
Parkinson created and led the multi-service military development program office. The program was named Navigation System Using Timing and Ranging (NAVSTAR GPS). The joint program included Navy, Army, Air Force, and Marine Corps officers, but the staff was dominated by Air Force officers with advanced degrees. They received critical support from the civilian Aerospace Corporation. As the program's first manager, Parkinson was the "chief architect" of GPS during its conception, development, and implementation.
Parkinson guided GPS through the development phase, developing the GPS satellites, ground systems, user equipment and an extensive test program. The first GPS satellite was launched 44 months later -- lightning speed in the satellite business. This phase successfully launched the first GPS satellites, tested the user equipment, and verified its accuracy. With the validation complete, Parkinson retired from the Air Force in 1978.
The GPS signal is open to both military and civilian users, a decision Parkinson fought for vigorously, and to which he attributes the current usefulness of the technology. Although it eventually provided a substantial benefit to humanity, the primary objective was the precise delivery of bombs. Parkinson understood, as well as anyone, the benefit of precision weapon delivery. He said, if we can land airplanes within two inches of accuracy, " . . . there's no reason in my opinion that we can't devise systems and operational procedures to drop bombs within a meter or two of a target. With this accuracy it is possible to take out military targets, reducing or avoiding collateral damage. It is humanitarian in the sense that the military hits what the military has to hit, and does not hit things that should not have been hit."
Following his retirement from the military, Parkinson continued his involvement with GPS. As professor of Aeronautics and Astronautics at Stanford University, where he began teaching in 1984, he promoted new uses for GPS technology in nonmilitary applications. He inspired a new generation of GPS scientists to develop hundreds of system enhancements and applications. Under FAA sponsorship, Parkinson and his students developed a fully blind landing system for aircraft, a technology whose trial resulted in more than 100 successful landings of a Boeing 737 without human assistance. The same principles were used to develop the first GPS auto-guided farm tractor capable of tracking to a predetermined line within two inches on an unmarked field.
GPS is now a critical component of military operations and is used in many worldwide applications, such as national defense, air traffic control, mechanized farming, search and rescue, and tracking environmental change. Most cell phones now include GPS receivers capable of providing block-by-block directions for drivers and pedestrians. Civilian airplanes have also incorporated GPS receivers for navigation. With GPS, airplanes are now capable of performing landings on autopilot more precisely and safer than human pilots.
Parkinson was a co-recipient of the Charles Stark Draper Prize in February 2003, sharing the award with Dr. Ivan Getting. The Draper Prize -- the engineering profession's equivalent of the Nobel Prize -- recognizes engineering achievements that have led to important contributions to everyday life. The citation for the prize states: "For pioneering the concept and development of a Global Positioning System that, with incredible precision, tells you where you are and helps you get to where you want to be."
NOTE: This short biography has been compiled from information in the nomination form submitted to the Minnesota Inventors Hall of Fame, magazine articles, a 2003 Steven Strom interview with Dr. Parkinson, and other internet postings and sources.