A short history of GPS development

SCHRIEVER AIR FORCE BASE, Colo. --  GPS IIF satellite. (USAF Graphic)

SCHRIEVER AIR FORCE BASE, Colo. -- GPS IIF satellite. (USAF Graphic)

SCHRIEVER AIR FORCE BASE, Colo. -- Today, technological advances occur seemingly in the blink of an eye.  As a culture, humankind takes for granted the technology that influences our everyday lives.  I remember watching the original Star Trek series on television and marveling at the communications devices they used.  Now, flip phones are the antiquities of the late 20th century.  As a child, I once saw a photograph of a computer that took up nearly an entire room.  Today, they fit in our pockets.  When I began in scouting, navigation meant having a compass and a map, and a sense of adventure.  Today's navigation, based on radio signals from orbiting satellites, grants many of us the luxury of knowing where we are and how to get where we want to go at the touch of a screen.  The road to that capability, however, was a long one.

When the Soviets launched Sputnik in October 1957, physicists and scientists at John Hopkins University's Applied Physics Laboratory, listening to the "beep, beep, beep" of the satellite's signal, were inspired to contemplate the use of Doppler shift, the change in the timing of the satellites signal used to determine the vehicle's location in orbit, in a reverse process to determine a precise position on earth.  Radio Direction Finding had been around since World War II.  That however, only provided two-dimensional location.  As the Air Force worked toward the development of Intercontinental Ballistic Missiles, the need for a three-dimensional locating and guidance system for those missiles was evident.

The Naval Research Laboratory had been experimenting with positioning satellites since 1960, when it launched the first of its Transit satellites.  These satellites used the concept developed at the Advanced Physics Laboratory to provide Navy ships and submarines with two-dimensional (longitude and latitude) positioning information.  This capability was also made available to commercial shipping.  The satellite, however, did not include a timing signal.  In 1964, the Navy launched the first of its Time and Navigation (TIMATION) satellites.  TIMATION showed that the use of passive ranging techniques using highly accurate clocks could for the basis of a revolutionary new satellite navigation system providing three-dimensional coverage.  The United States Army also experimented with satellite positioning, developing the Sequential Collation of Range satellite.  This small geodetic satellite system operated using three fixed stations and a fourth on the location to be determined.  The SECOR satellite program preceded TIMATION and provided additional knowledge and technologies that would be used in the development of the Global Positioning System.

The Air Force also began working on the development of a space-based radio navigation system, ultimately designated Program 621B.  Eventually, the Navy's TIMATION program and the Air Force's Program 621B merged and became the Navigation Satellite Timing and Ranging program with the Air Force serving as the executive agency.  The Navy's TIMATIOJN-3 satellite, became the first launch under the NAVSTAR program, but did not carry the Global Positioning System moniker.  Instead, the satellite was designated Navigation Technology Satellite (NTS) - 1 and launched on July 7, 1974.  The satellite operated for five years.  Following a second NTS launch June 23, 1977, the first NAVSTAR GPS launch occurred on Feb. 22, 1978 from Vandenberg AFB, California.  Over the next seven years, the Air Force successfully launched ten developmental GPS satellites, which were controlled from Vandenberg Air AFB. 

On Sept. 26, 1985, Falcon Air Force Station opened and the 2d Space Wing began the arduous process of planning and preparing to formally open the Consolidated Space Operations Center from which many of the Department of Defense's satellites, including the Global Positioning System, would be operated.  Four years later, on Feb. 14, 1989, the Air Force launched the first of the operational Block II satellites and by the year's end, on-orbit control of GPS satellites had transitioned to the 2nd Satellite Control Squadron (now 2nd Space Operations Squadron).  Within one year, the squadron and its GPS crews would be challenged as the United States and coalition partners initiated Operation DESERT SHIELD, the defense of Saudi Arabia. 

By Aug. 2, 1990, the date Iraqi armed forces crossed the border and began an occupation of Kuwait, the Air Force had launched eight operational Block II GPS satellites, with an additional eight developmental Block I satellites still on orbit.  This comprised only three-fourths of the planned operational constellation of 24 satellites.  As Desert Shield continued and coalition forces prepared for a probable action to force Iraqi military units from Kuwait (Desert Storm), the Air Force accelerated the launch schedule of GPS satellites and orbited a satellite in each month of October and November 1990.  The 1st Space Control Squadron crews quickly completed early orbit and check-out procedures and placed the satellites in operation in record time before handing them off to the 2 SCS for daily operations.  The 1 SCS (later renamed 1st Space Operations Squadron) continued to perform launch, early orbit, anomaly resolution, and end-of-life operations for the GPS constellation until 2008.

Although the GPS constellation would not reach full operational capability for four more years, U.S. military units had begun incorporating GPS capability into their forces.  Still, that process had been slow and many deploying units did not have GPS capability.   Army units, as well as individual soldiers and Marines, bought commercial GPS receivers, especially the small lightweight GPs receiver (SLGR) and the Trimble 1000M, to mount on their vehicles.  Air Force units hurriedly purchased GPS units to improve the accuracy of their bombs, rockets, and missiles.  At Schriever AFB, 1 SCS and 2 SCS crews developed a procedure to return a malfunctioning satellite to limited operational status, improving GPS accuracy in the theater of operations.

The air campaign for Desert Storm began on the morning of Jan. 17, 1991.  For many at home, news imagery of missiles going down building shafts and into windows illustrated the lethality and precision of GPS-guided munitions.  United States and coalition air forces quickly eliminated Iraq's command and control capability and its air force's ability to harass coalition ground forces.  When the ground offensive began in earnest on February 24, the U.S. Army reported about 4,000 GPS receivers assigned to its forces.  The Global Positioning System allowed these units to advance in a featureless desert at night, during inclement weather, and to engage Iraqi units with a lethal accuracy unknown to that point. 
GPS achieved full operational capability in April 1995 and in the subsequent 21 years, has become an unnoticed feature of modern life.  From the time stamp on ATM receipts, international banking, sports and recreation uses, search and rescue activities, humanitarian operations, and the ability of us all to make and receive cell phone calls and texts, GPS has become an integral part of our everyday activities. 

Today, the 2nd Space Operations Squadron operates the largest military constellation in the world with 30 operational satellites, providing highly accurate, all-weather position, velocity and timing data to users worldwide.  Around the world, there are 16 geographically separated sites housing ground antennas and stations that help to fly and monitor the GPS constellation.  The 2 SOPS works in conjunction with their reserve counterpart, 19 SOPS, to conduct launch, anomaly resolution, and disposal operations. LADO incorporates launch and early-orbit operations, including satellite activation, initial checkout and maneuvering to mission orbit. LADO also responds to all satellite emergencies, supports end-of-life testing, and executes satellite disposal operations as required.