by GPS Directorate
1/14/2014 - LOS ANGELES AIR FORCE BASE, El Segundo, Calif. -- The
Global Positioning System (GPS) Directorate celebrated the 20th
Anniversary of achieving Initial Operational Capability (IOC) for GPS
Dec. 8, 2013.
In 1973, the Navstar Global Positioning System Joint Program Office
(JPO), headed by then-Colonel Bradford Parkinson, developed the GPS
architecture and initiated efforts to field a prototype system to prove
the concept of space-based global navigation would work. Since that
time, GPS has evolved from an idea, to a prototype, to a global utility.
It continues to evolve, with modernization bringing forth new
capabilities for the 21st century.
Since the launch of the prototype Block 0 satellite June 22, 1977, GPS
has provided high quality navigation signals to suitably equipped users
across the globe. Beginning in 1978, after the first four developmental
Block-I satellites were launched, GPS started to provide full
4-dimensional positioning, navigation, and timing (PNT) services to
military and civilian users on a limited, but worldwide, basis. By 1985,
the seven remaining developmental Block I satellites were launched to
expand the availability of PNT services around both time and space. The
second stage of GPS began Feb. 14, 1989 when the first operational Block
II satellite was launched into orbit. More Block II and Block IIA
launches followed rapidly thereafter until, Dec 8, 1993, United States
Air Force Space Command (AFSPC) declared IOC for GPS when a grand total
of 24 Block I and Block II/IIA satellites were operating in their
individual orbits and providing the Standard Positioning Service (SPS)
to civilian users and the Precise Positioning Service (PPS) to
authorized military users.
After IOC, additional Block IIA satellites were launched to fully
populate the baseline operational constellation of 24 slots arranged in
six orbital planes --the remaining developmental Block I satellites
continued providing high quality navigation signals even though they
were not part of the baseline operational constellation. Once system
testing was complete,
AFSPC declared Full Operational Capability (FOC) for the GPS
constellation April 27, 1995, signifying the system met all requirements
with 24 operational Block II/IIA satellites in their assigned orbital
slots and providing both the military PPS and the civil SPS.
Today, the GPS constellation remains healthy, stable and robust with 31
operational satellites on-orbit broadcasting the PNT services 24 hours a
day, 7 days a week, 365 days a year. In the 20 years since IOC, GPS has
never failed to deliver on the global PNT service commitments made by
the Department of Defense in the PPS Performance Standard (PPS PS) and
in the SPS Performance Standard (SPS PS) - both of which trace directly
back to the original Global Positioning System (GPS) Standard
Positioning Service Signal Specification (SPS SS) which was officially
promulgated on Dec. 8, 1993 by the Assistant Secretary of Defense for
Command, Control, Communication and Intelligence (C3I) as the formal
document which defined IOC. Amazingly, though many Navstar satellites
have been launched and been decommissioned over the past 20 years, four
of the original Block IIA satellites which made up the IOC constellation
(SVN-23, SVN-26, SVN-34, and SVN-39) are still operating and providing
reliable PNT services as of this 20th Anniversary of IOC.
GPS has grown to become a vital worldwide utility serving billions of
users around the globe. GPS multi-use PNT services are integral to the
United States global security, economy, and transportation safety, and
are a critical part of our national infrastructure. GPS contributes
vital capabilities to our nation's military operations, emergency
response, agriculture, aviation, maritime, roads and highways, surveying
and mapping, and telecommunications industries, as well as recreational
activities. It is not an overstatement to say GPS is fundamental to
today's technical infrastructure and culture. GPS provides the 'winning
edge' to our warfighters and allies by delivering premier space-based
PNT services to the nation and the world.
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