eleven o'clock ... do you know where your kids are? Would you like
to? One way to track them would be to have a GPS receiver installed
in the car! The GPS, or Global Positioning System, is one of the
hottest technologies around, and no wonder. Consider these diverse
scientists use GPS to study movements and feeding habits of
- Surveyors used GPS
to measure how the buildings shifted after the bombing in Oklahoma
GPS help settle property disputes between land owners.
archaeologists use GPS to guide research vessels hunting for
data has revealed that Mt. Everest is getting taller!
GPS answers five questions
- "Where am I?"
- "Where am I
- "Where are
- "What's the
best way to get there?
- "When will
I get there?"
GPS is the only system
today that can show your exact position on the Earth anytime,
in any weather, no matter where you are!
Like so many other high-tech developments, GPS was designed
by the U. S. military. The concept started in the late '60s
but the first satellite wasn't launched until February 1978. In
1989 the Magellan Corp. introduced the first hand-held GPS receiver.
In 1992 GPS was used in Operation Desert Storm. On March 1996 the
President decided to make GPS free for civilian users.
GPS has three 'segments':
The space segment now consists of 28 satellites, each
in its own orbit about 11,000 nautical miles above the Earth.
user segment consists of receivers, which you can hold
in your hand or mount in your car.
control segment consists of ground stations (five of
them, located around the world) that make sure the satellites
are working properly.
At first, the military did not want to let civilians use GPS, fearing
that smugglers, terrorists, or hostile forces would use it.
bowing to pressure from the companies that built the equipment,
The Defense Department made GPS available for non-military purposes,
with some restrictions. On May 1, 2000, President Clinton lifted
the restrictions, and announced that the option to degrade civil
GPS signals during emergencies would be phased out by 2010. The
federal government is committed to providing GPS technology
peaceful uses on a worldwide basis, free of charge.
Wormley's Global Positioning System Resources - Sam
Wormley's Web site provides numerous links to Web resources
on Global Positioning Systems. His site includes an extensive
bibliography of books on the subject of Global Positioning.
This educational observatory site also helps K-12 students
do real science via the Internet.
Global Positioning System Overview - These materials
were developed by Peter H. Dana, The Geographer's Craft
Project, and the Department of Geography at the University
of Colorado in Boulder. It provides an overview of global
positioning systems, a reference list, and related links
Coast Guard Navigation Center Global Positioning System
(GPS) - This Web site has general information about
GPS. It includes the United States policy statement regarding
(a GPS online game) - "A GPS device and a hunger
for adventure are all you need for high tech treasure hunting.
Here you can find the latest caches in your area, how to
hide your own cache, and what you need to get started in
this fun and exciting sport."
B., H. Lichtenegger and J. Collins. Global positioning
system: theory and practice. New York, Springer-Verlag,
c2001. 382 p.
of Navigation. Global positioning systems: papers published
in navigation. Alexandra, VA, Institute of Navigation.
1984-1999. 7 v.
GPS: principles and applications.
Edited by Elliott D. Kaplan. Boston, Artech House, c1996.
more print resources...
Search on "GPS,"
or "global positioning system"
in the Library of Congress Online
Positioning System Overview from The Geographer's Craft at University
Diagram of GPS "segments" from EPA
page on how Army used GPS tocontrol infestation of June bugs.
Sheriff on patrol with gps. Counterdrug
Technology Assessment Center
Earth \ NASA
- Goddard Space Flight Center Scientific Visualization Studio.
Earth \ photo
taken by the Galileo spacecraft
\ 1992 \ Destination Earth.