See: http://earth.agu.org/revgeophys/yunck00/node9.html
http://edu-observatory.org/gps/gps_accuracy.html
http://www.redsword.com/GPS/apps/general/misuse.htm
Both the NAVSTAR and GLONASS systems were
conceived as military systems, intended to augment
military
weaponry in times of war. However, GPS is a classic
example
of a dual use system. That is, one which has both
military and
civilian uses. In this case, GPS is an extremely
expensive
publiclly funded system which has potentially massive
civilian benefits.
Situations In Which Misuse Could Occur
Attacker vs. Country of Origin
In this case, the enemy
would be directly attacking the
GPS system's creator by
using it's own system against
it. Example: Iraq using
NAVSTAR augmented weapons
vs. the United States.
Attacker vs. Ally
In this case, the enemy
would be attacking an ally of the
GPS system's creator using
the GPS system. Example:
Iraq using NAVSTAR augmented
weapons vs. Saudi
Arabia.
Attacker vs. other nation
In this case, the attacker
would be attacking a nation
not allied with the GPS
system's creator. Example:
Libya using NAVSTAR augmented
weapons vs. Chad.
Types of Misuse
Intelligence collection
GPS combined with laser
rangefinding systems permits
accurate positioning of
potential targets from a
distance. Information resulting
from such data
collection can be attacked
at a later time using a variety
of methods. These would
include infantry assault, air
attack, artilltery, etc.
Augmentation of existing weapon systems
Potential for terrorist
use in short range mortar attacks.
Postprocessed mapping grade
differential GPS
combined with commercial
laser rangefinders could be
used to surreptitiously
map potential targets with
respect to potential hiding
spots for mortars. This
would allow for better first
shot accuracy with most any
indirect fire weapon.
Similarly, military artillery
batteries can shorten the
time needed to survey in
guns before they begin
operation. This is relatively
important in modern
warfare because artillery
batteries must move often to
keep from being hit from
counterfire. This principle is
demonstrated in the U.S.
Army's MLRS surface to
surface missile system.
The MLRS vehicle can carry up
to eight unguided rockets
in one tracked vehicle. An
inertial guidance system
in the vehicle is used to
position the vehicle and
aim the launch box at the
target. A single MLRS vehicle,
such as the one shown
below, can stop, aim, shoot
and leave within four
minutes while providing
the firepower of an entire
battery.
Integration into ballistic missile systems
A RAND study has shown that
the accuracy of short
range ballistic missiles
such as the Scud or the No Dong
I can be improved by 20%
to 25% by using the civilian
SPS GPS signals. The GPS
receiver is used to provide
more accurate boost phase
velocity measurements to
the guidance system. Differential
correction provides
little added benefit because
other systemic errors begin
to dominate. Longer range
ballistic missiles benefit
more because they are more
affected by boost velocity
errors.
Integration into cruise missile systems
Biological weapons can be
dispersed more easily and
more effectively from a
cruise missile than from a
ballistic missile. Even
civilian grade GPS provides
sufficient accuracy for
a low cost cruise missile to lay
down a biological toxin
such as anthrax in a desired
pattern.
RAND
The RAND Corporation is a federally funded research
group
that focuses on national and military issues. The
organization
was formed to be a U.S. Air Force think tank studying
nuclear weapons targeting issues in the '60s. RAND
has
several papers on GPS, some discussing the use of
GPS for
ballistic missile guidance. These papers may be
ordered
directly from RAND.