Military Lasers Will Change The Face Of Warfare Source: USA Today "The Air Force says the program is needed because 30
nations have more than 10,000 theater ballistic missiles on which they
can mountchemical, biological or nuclear warheads."
By the time Capt. James T. Kirk was blasting
fictitious Klingons with the starship Enterprise's phaser in 1966, the
Air Force had all but given up trying to invent a similar weapon to
shoot down missiles.
It didn't take long for scientists to conclude in the
early 1960s that the world's most powerful lasers were too weak to
punch holes in a missile and that aiming devices couldn't even come
close to tracking the fast-moving targets.
But today, the Air Force says, advances in a variety of
scientific areas from astronomy to airliner design have led
scientists to the brink of bridging that gap between science fiction
and reality.
A Boeing 747 jumbo jet is being built and outfitted
with one of the world's most powerful lasers. Within three years,
scientists say, this flying laser will shoot down its first Scud-type
missile much the way Capt. Kirk blasted those Klingons.
Backers say the airborne laser will change the way
America defends itself.
"We've got a weapon now that operates at the speed of
light," says Paul Shennum, vice president of the Airborne Laser
Program at the Boeing Co., which leads the private industry team
working on the project. "Try to develop countermeasures to a system
that deploys that kind of energy."
If the first airborne laser works as expected, six
more will follow. The cost of the program, from the first ground tests
to maintaining the seven aircraft for 20 years, is expected to be
$11.2 billion.
The Air Force says the program is needed because 30
nations have more than 10,000 theater ballistic missiles on which
they can mount chemical, biological or nuclear warheads. The
military likes the idea of using the laser to destroy these missiles
during their boost phase, when they are climbing out of enemy
territory. The warhead and other debris would fall close to the launch
pad, away from U.S. troops.
But beyond the military use, the scientific leap also
may lead to advancements in other areas, from spying to avoiding
turbulence on commercial airline flights.
"I think we're just beginning to open the door," says
Shennum, who compares the invention to the creation of radar or
stealth technology.
Fire One!
In the heart-pounding seconds after an enemy missile has
been fired at U.S. troops, an array of advanced technology aboard the
jet will focus on the airborne threat.
Today, missile launches are detected and tracked from
command centers in the USA. When crews back home determine
via satellites where the missile is heading, warnings are sent to
take cover.
The airborne laser jet will have a more sophisticated
laser tracking system that can pinpoint the position of the missile as
it races through the sky to within a fraction of an inch.
The jet, cruising at 40,000 feet hundreds of miles
from the missile, tracks the missile as it climbs at speeds ranging
from Mach 4 to Mach 5, or nearly five times the speed of sound.
For years the Air Force has tried to find a way to
down missiles during this boost phase, but the fastest tools in the
arsenal were fighter jets, which were too slow.
"You just can't close that loop with an F-15," says
Col. Mike Booen, director of the Airborne Laser System Program Office
at New Mexico's Kirtland Air Force Base. "Only the speed of light can
close that loop."
But the laser blast, which is invisible, is
vulnerable to distortion in the atmosphere.
Pockets of air that vary in temperature, the same
invisible forms responsible for the bumps air travelers know as clear
air turbulence, can act like prisms to distort the shape of the laser
as it passes through.
To counter this problem, designers use the lasers
that track the missile to measure the distortion in the air. By
measuring how much those lasers are distorted as they pass from jet to
missile and back again, computers calculate how to change the shape of
the laser weapon as it is fired.
Shaping the beam
The key to this trick is "rubber mirrors," which have
been perfected by astronomers looking through the atmosphere deep into
space. Astronomers found that when a crooked beam of light bounced off
a crooked mirror, it could result in a straight beam of light.
The mirror in the nose of the jet works the same way,
only faster, as the missile climbs through the air. Only a few microns
thick, this coated sheet of glass can be moved by finger-like
actuators to send the laser out in different shapes.
During the five-second shot, these actuators can move
thousands of times each second. The laser is distorted by the mirror
as it is fired and then is corrected by the air turbulence, which
basically focuses the beam on the target.
The laser team's understanding of turbulence may
someday help other scientists who are trying to perfect lasers to
detect and warn airline pilots of invisible turbulence. "We are
learning a lot about the atmosphere," Shennum says.
Since the mirror is really a flying telescope, it
could also be turned toward the ground for closer looks at the enemy.
Powerful blast
Within a few seconds after the missile is detected in
the air, the settings for the rubber mirror are determined, and the
laser can be fired.
The laser is created by the Chemical Oxygen Iodine
Laser, which mixes common chemicals in a way that produces an
uncommonly strong blast.
While it was the science of looking to the stars that
led to the rubber mirror, the laser is based on a development by a
telephone company.
The first carbon dioxide laser came in 1964 when a
Bell Telephone scientist named Charles Patel found that the gas was a
good medium for a laser. This kind of laser is now one of the most
powerful in the world.
But to work in flight, the beam must pass
uninterrupted from the back of the plane, where it is generated,
through the nose, where the rubber mirror is mounted. The team had to
devise shock absorbers for each part of the system to adjust for
in-flight bumps.
Engineers flew a test 747 around the world measuring
vibrations with 128 pressure sensors. The tests showed them how much
they did not understand about how jumbo jets bump in flight.
"You would think the Boeing Co. would understand how a
747 shakes, rattles and rolls," Shennum says. "But
passenger comfort is not like a laser."
As the laser passes through the nose turret in the
plane, it expands from a foot in diameter to 4 feet wide " the size it
will be when it hits the missile.
Within five seconds, the laser beam breaches the
shell of the missile's rocket booster, causing the missile to explode.
New way to fight
In battle, the plane would be protected by fighter
jets during its 12-hour mission. A tanker plane would refuel the
jumbo jet in flight after the first six hours of patrolling the skies.
Booen says the laser is designed never to miss its
target. It won't fire if it doesn't have a shot.
Another key technology of the '90s that allows
today's scientists to do what their 1960s counterparts could not is
the modern supercomputer.
The computer that Boeing used to design the 777
commercial airliner allowed the airborne laser team to combine the
work of 22 teams in 11 states to perfect the laser weapon system.
The computer allows engineers to put systems through
tests without taking the time to build each part.
"This Star Wars technology is reality today," Shennum
says.
"This is just the first step," Booen says. "The next
question is, how do we make it smaller? Can we put this on a fighter
jet? This really should alter the way America fights war."
By Robert Davis
September 5, 1998