©Mark
Ollig
The
global positioning system (GPS) we use in our car and smartphones is operated
and maintained by the US Air Force.
Currently,
the US Navstar GPS satellite constellation includes a network of 24 primary
satellites providing free navigational services to citizens located anywhere on
the planet.
Navstar
was first proposed as a global positioning satellite system by the Pentagon in
1973. Its first GPS I satellite was launched in 1978.
GPS
II satellites were sent into Earth-orbit beginning in 1989, with the last in
2016.
This
year, those satellites are in the process of being replaced by GPS III
satellites.
The
first set of GPS III satellites is named Block IIIA; the following set is
called Block IIIF.
GPS
III is the future generation Earth-orbiting US GPS navigational satellites.
The
first of 10 GPS Block IIIA satellites was launched Dec. 23, 2018, using a SpaceX
Falcon 9 rocket. It currently orbits the Earth twice every 24 hours at an
altitude of 12,550 miles. and will be undergoing testing for the next 12
months.
The
second GPS Block IIIA satellite is slated to be launched in July.
Block
IIIA satellites will provide three times better accuracy than current GPS II
satellites.
All
10 Block IIIA satellites are expected to be operational by 2022.
Looking
ahead, the first of 22 planned GPS Block IIIF satellites is scheduled to launch
in 2026, and the last in 2034. Their operating life is yet to be determined.
It’s
not publicized much, but since 1980, GPS satellites have been equipped with
thermonuclear detonation sensors for detecting nuclear explosions anywhere on
the planet. It is called The GPS Nuclear Detonation Detection System.
This
information is not classified; but, for the most part, not generally known by
the public.
If
a nuclear explosion did occur, the data from all satellites observing it would
be transmitted to ground stations for immediate processing.
Atomic
clocks are recognized as the most accurate time and frequency standard.
Each
Block IIIA satellite has a built-in rubidium atomic clock, which is
synchronized with the other satellites’ clocks.
There
are three GPS segments: space, control, and user.
The
US Air Force manages, performs upgrades, and maintains the space and control
segments of the GPS.
The
space segment is made up of the actively-operating GPS satellites transmitting
to Earth their orbiting position and other operating data.
The
control segment is comprised of 16 global monitoring stations geographically
located around the world. It also includes 11 command and control antennas.
The
master control station is located and operated by the 2nd Space Operations
Squadron at Schriever Air Force Base in Colorado Springs, CO.
The
personnel there ensures the GPS satellites stay in their proper orbit and
maintain clocking for correct timing. They also upload navigational data to the
spacecraft.
The
master control station is backed up by a fully-functioning alternate master
control station located at Vandenberg Air force Base in California.
Updates,
including software to protect against cybersecurity threats, are regularly made
to the control segments of the GPS.
The
user segment is the GPS receiver equipment (in our car or on our smart device)
we use to acquire data signals from GPS satellites.
The
streets and highway information presented on our GPS receiver screen are the
output from “moving mapping software,” which is decoding the triangulated
satellite signals, calculating, and then displaying our geographical position
and travel destination route.
The
operating lifespan for the new GPS Block IIIA satellites is 15 years, which is
25 percent longer than prior GPS satellites.
In
July, the second GPS Block IIIA satellite, named “Magellan” in honor of
Ferdinand Magellan, the Portuguese explorer, will be launched from Cape
Canaveral Air Force Station in Florida.
The
BeiDou Navigation Satellite System (BDS) is China’s version of our GPS.
April
20, China launched the 44th BDS satellite from the Xichang Satellite Launch
Center. The BDS website is http://en.beidou.gov.cn.
Russia’s
navigational satellite system is the Global Navigation Satellite System
(GLONASS). It has 26 (24 operational) Earth-orbiting satellites providing
worldwide coverage. Its website is https://www.glonass-iac.ru/en.
The
US government’s official GPS website is https://www.gps.gov.
Dated
July 27, 1983, the US Department of Energy Office of Scientific and Technical
Information’s 13-page paper, “The Nuclear Detonation Detection System on the
GPS Satellites,” can be viewed at https://bit.ly/2Vji5hm.
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| Illustration of a GPS IIIA satellite in Earth-orbit Source: gps.gov |
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| GPS III Space Vehicle 02 “Magellan” arrives in Florida in preparation for its July launch from Cape Canaveral Air Force Station. Source: gps.gov |
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| Illustration of a GPS II satellite in Earth-orbit Source: gps.gov |
