40th Anniversary of Key DoD Decision on GPS - Inside GNSS

40th Anniversary of Key DoD Decision on GPS

Brad Parkinson

Brad Parkinson, the first director of the NAVSTAR GPS Joint Program Office, once said that his work with the Global Positioning System had led him to validate an interpretation of “prime law” suggested by a colleague: one thing leads to another

Forty years ago today, that principle culminated in a key decision by the Department of Defense to proceed with what became the GPS program.


Brad Parkinson, the first director of the NAVSTAR GPS Joint Program Office, once said that his work with the Global Positioning System had led him to validate an interpretation of “prime law” suggested by a colleague: one thing leads to another

Forty years ago today, that principle culminated in a key decision by the Department of Defense to proceed with what became the GPS program.

On December 17, 1973, after rejecting an earlier approach, the Defense System Acquisition and Review Council (DSARC) approved development of what is now known as the NAVSTAR Global Positioning System, marking the start of concept validation (Phase I of the GPS program). In the words of a RAND Corporation history of the GPS program, “The new concept was really a compromise system negotiated by Col. [Brad] Parkinson that incorporated the best of all available satellite navigation system concepts and technology.”

In a 1999 IEEE Oral History interview with Michael Geselowitz, Parkinson observed, “I happened to be placed in charge of GPS. I had all the right background, but I don’t claim that the underlying pieces that we synthesized — I didn’t invent all those. I had a strong hand in some of the innovations in the testing area and also the exact selection of how we were going to do things, but fundamental technologies were pieces that we stole. I think what was needed was someone to pull all that together in one package and tie it off with a bow and say, ‘That’s GPS.’ I was lucky. I was lucky to be there.”

As identified by RAND in an appendix to its 1995 study for the National Research Council, The Global Positioning System: Assessing National Policies, here are key milestones leading up to the seminal DSARC decision that gave rise to the world’s first GNSS system.

1959
TRANSIT, the first operational satellite-based navigation system, is developed by the Johns Hopkins Applied Physics Laboratory (APL) under Dr. Richard Kirschner. Although Transit was originally intended to support the U.S. Navy’s submarine fleet, the technologies developed for it proved useful to the Global Positioning System (GPS). The first Transit satellite is launched in 1959.

1960
The first three-dimensional (longitude, latitude, altitude) time-difference-of-arrival navigation system is suggested by Raytheon Corporation in response to an Air Force requirement for a guidance system to be used with a proposed ICBM that would achieve mobility by traveling on a railroad system. The navigation system presented is called MOSAIC (Mobile System for Accurate ICBM Control). The idea is dropped when the Mobile Minuteman program is canceled in 1961.

1963
The Aerospace Corporation launches a study on using a space system as the basis for a navigation system for vehicles moving rapidly in three dimensions; this led directly to the concept of GPS. The concept involves measuring the times of arrival of radio signals transmitted from satellites whose positions are precisely known. This gives the distances to the known satellite positions—which, in turn, establishes the user’s position.

1963
The Air Force begins its support of the Aerospace study, designating it System 621B. By 1972, the program has already demonstrated operation of a new type of satellite-ranging signal based on pseudorandom noise (PRN).

1964
Timation, a Navy satellite system, is developed under Roger Easton at the Naval Research Lab (NRL) for advancing the development of high-stability clocks, time-transfer capability, and 3-D navigation. Timation’s work on space-qualified time standards provided an important foundation for GPS. The first Timation satellite is launched in May 1967.

1968
DoD establishes a tri-service steering committee called NAVSEG (Navigation Satellite Executive Committee) to coordinate the efforts of the various satellite navigation groups (Navy’s Transit and Timation programs, the Army’s SECOR or Sequential Correlation of Range system). NAVSEG contracted a number of studies to fine-tune the basic satellite navigation concept. The studies dealt with some of the major issues surrounding the concept, including the choice of carrier frequency (L-Band versus CBand), the design of the signal structure, and the selection of the satellite orbital configuration (a 24- hour figure 8s constellation versus “Rotating Y” and “Rotating X” constellation).

1969–1972
NAVSEG manages concept debates between the various satellite navigation groups. The Navy APL supported an expanded Transit while the Navy NRL pushed for an expanded Timation and the Air Force pushed for an expanded synchronous constellation “System 621B.”

1971
L2 frequency is added to the 621B concept to accommodate corrections for ionospheric changes.

1971–1972
User equipment for the Air Force 621B is tested at White Sands Proving Ground in New Mexico. Ground and balloon-carried transmitters simulating satellites were used, and accuracies of a hundredth of a mile demonstrated.
 
April 1973

The Deputy Secretary of Defense determines that a joint tri-service program be established to consolidate the various proposed positioning/navigation concepts into a single comprehensive DoD system known as the Defense Navigation Satellite System (DNSS). The Air Force is designated the program manager. The new system is to be developed by a joint program office (JPO), with participation by all military services. Colonel Brad Parkinson is named program director of the JPO and is put in charge of jointly developing the initial concept for a space-based navigation system.

August 1973
The first system presented to the Defense System Acquisition and Review Council (DSARC) is denied approval. The system presented to DSARC was packaged as the Air Force’s 621B system and therefore not representative of a joint program. Although there is support for the idea of a new satellite-based navigation system, the JPO is urged to broaden the concept to include the views and requirements of all the services.