Airborne Laser
Source: Federation of American Scientists
The ABL weapon system will use a high-energy, chemical
oxygen iodine laser (COIL) mounted on a modified 747-400F (freighter)
aircraft to shoot down theater ballistic missiles in their boost
phase. A crew of four, including pilot and copilot, will operate the
airborne laser, which will patrol in pairs at high altitude, about
40,000 feet. The jets will fly in orbits over friendly territory,
scanning the horizon for the plumes of rising missiles. Capable of
autonomous operation, the ABL will acquire and track missiles in the
boost phase of flight. A tracking laser beam will illuminate the
missile, and computers will measure the distance and calculate its
course and direction. After acquiring and locking onto the target, a
second laser - with weapons-class strength - will fire a three- to
five-second burst from a turret located in the 747’s nose. The
missiles will be destroyed over the launch area.
The airborne laser will fire a Chemical Oxygen Iodine
Laser, or COIL, which was invented at Phillips Lab in 1977. The
laser’s fuel consists of the same chemicals found in hair bleach and
Drano - hydrogen peroxide and potassium hydroxide - which are then
combined with chlorine gas and water. The laser operates at an
infrared wavelength of 1.315 microns, which is invisible to the eye.
By recycling chemicals, building with plastics and using a unique
cooling process, the COIL team was able to make the laser lighter and
more efficient while - at the same time - increasing its power by 400
percent in five years. The flight-weighted ABL module will be similar
in performance and power levels to the multi-hundred kilowatt class
COIL Baseline Demonstration Laser (BDL-2) module demonstrated by TRW
in August 1996. As its name implies, though, it will be lighter and
more compact than the earlier version due to the integration of
advanced aerospace materials into the design of critical hardware
components. For the operational ABL system, several modules will be
linked together in series to achieve ABL’s required megawatt-class
power level.
Atmospheric turbulence, which weakens and scatters the
laser’s beam, is produced by fluctuations in air temperature [the same
phenomenon that causes stars to twinkle]. Adaptive optics relies on a
deformable mirror, sometimes called a rubber mirror, to compensate for
tilt and phase distortions in the atmosphere. The mirror has 341
actuators that change at a rate of about a 1,000 per second.
The Airborne Laser is a Major Defense Acquisition
Program. After the Concept Design Phase is complete, the ABL will
enter the Program Definition and Risk Reduction (PDRR) Phase. The
objective of the PDRR phase is to develop a cost effective, flexible
airborne high energy laser system which provides a credible deterrent
and lethal defensive capabilities against boosting theater ballistic
missiles.
The ABL PDRR Program is intended to show high confidence system
performance scalable to Engineering and Manufacturing Development
(EMD) levels. The PDRR Program includes the design, development,
integration, and testing of an airborne high-energy laser weapon
system.
In May 1994, two contracts were awarded to develop fully
operational ABL weapon system concepts and then derive ABL PDRR
Program concepts that are fully traceable and scaleable EMD. A single
contract team was selected to proceed with the development of the
chosen PDRR concept beginning in November 1996. Successful development
and testing of the laser module is one of the critical ’exit criteria’
that Team ABL must satisfy to pass the program’s first
’authority-to-proceed’ (ATP-1) milestone, scheduled for June 1998.
Testing of the laser module is expected to be completed by April 1998.
The PDRR detailed design, integration, and test will culminate in a
lethality demonstration in the year 2002. A follow-on Engineering
Manufacturing and Development/Production (EMD) effort could then begin
in the early 2003 time frame. A fleet of fully operational EMD systems
is intended to satisfy Air Combat Command’s boost-phase Theater Air
Defense requirements. If all goes as planned, a fleet of seven ABLs
should be flying operational missions by 2008.
Performance requirements for the Airborne Laser Weapons
System are established by the operational scenarios and support
requirements defined by the user, Air Combat Command, and by measured
target vulnerability characteristics provided by the Air Force
lethality and vulnerability community centered at the Phillips
Laboratory. The ABL PDRR Program is supported by a robust technology
insertion and risk reduction program to provide early confidence that
scaling to EMD performance is feasible. The technology and concept
design efforts provide key answers to the PDRR design effort in the
areas of lethality, atmospheric characterization, beam control,
aircraft systems integration, and environmental concerns. These
efforts are the source of necessary data applied to exit criteria
ensuring higher and higher levels of confidence are progressively
reached at key milestones of the PDRR development.
The key issues in the program will be effective range of
the laser and systems integration of a Boeing 747 aircraft.
More information
HERE
http://www.fas.org/spp/starwars/program/abl.htm