A military and industry team announced this week that a Lockheed
Martin-built system here can control a laser beam to the levels needed for the
U.S. Air Forcešs Airborne Laser to kill attacking missiles.
Successful laboratory tests addressed a key issue in the development of the
weapon system: how to point and focus a laser accurately at a hostile missile
hundreds of miles away despite vibration in the aircraft and optical turbulence
in the atmosphere. All this in a laser-versus-missile battle that could last
only a few seconds. The experiments were conducted on a scaled-down demonstrator
version of a beam control system that functionally reproduced all elements of
the full-scale Airborne Laser beam control system.
These latest tests provided a firm foundation for the Air Force to proceed
toward the final design, manufacture and implementation of the Air Forcešs aircraft-based
theater missile defense system.
The Airborne Laser, or ABL, involves a Boeing 747-400 freighter aircraft that
will be modified to carry a high-energy laser. ABL is designed to operate over
friendly territory at altitudes above 40,000 feet. There, the aircraft can acquire,
track and accurately fire a lethal beam of laser energy on an attacking missile
shortly after that missile has been launched. It is during this portion of a
missile's flight the boost phase when the missile is most vulnerable. By
destroying a missile during this phase, there is a strong likelihood that its
warhead and debris will fall back on the country that launched it.
"This successful demonstration validates the tracking, pointing hardware
and algorithms approach necessary for the ABL mission," said Paul Shattuck,
Lockheed Martin Missiles & Space ABL program manager. "This clearly shows
the ABL program is ready to proceed into the critical design phase of the Program
Definition and Risk Reduction Program."
To ensure the sophisticated beam control flight system was properly designed,
Lockheed Martin developed a laboratory demonstrator to simulate the flight hardware
as well as the disturbances such as aircraft platform motion and atmospheric
turbulence to which the hardware must respond.
A major technical challenge for ABL is the long distances that a laser beam
must travel through the atmosphere, which causes distortion on that beam. These
atmospheric effects were measured by the Air Force and used by Lockheed Martin
in its demonstrator to create high-fidelity optical simulations. The data was
also used to make atmospheric-simulation optics that permitted reproducible
and controllable evaluations of the system's design.
"This testing approach will produce a final beam control design with greatly
diminished risk to performance and cost," explained Paul Shennum, Boeing
ABL program manager.
These laboratory tracking demonstrations started as a series of tests that
began in 1994 to ensure that scientists could correct for optical distortions
in the atmosphere and jitter (movement on the laser beam caused by aircraft
vibration). Aircraft-induced vibrations are attenuated using passive isolators
for the low frequency components and compensated with fast steering mirrors
for the high frequency components. The ability to control aircraft and atmospheric
disturbances to the 100 nanoradian level has been demonstrated in scaled testing
at the Palo Alto facility.
In the next phase of the laboratory beam control tests, measurements will be
made to determine the missile kill range and its variability under a full spectrum
of atmospheric turbulence under which ABL may have to operate.
The Airborne Laser program is managed by the ABL System Program Office at Kirtland
Air Force Base, N.M. The program office is part of the Space and Missile Systems
Center at Los Angeles Air Force Base, Calif.
