Space


Airborne Laser

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. The prototype ABL aircraft, dubbed the YAL-1A, made its first flight in July 2002. Development efforts are focused on integrating the system's sophisticated laser and tracking elements on board the airframe to support a planned intercept of a threat-representative short-range ballistic missile over the Pacific Ocean in late 2004.

As of late 2002, it appeared that the Airborne Laser's first missile intercept test, scheduled for the fourth quarter of calendar year 2004, might be postponed due to hardware problems. This lethality demonstration had been scheduled for 2003, but by early 2002 had slipped to the first quarter of FY-05.

Under the FY '04 budget plan released earlier in 2003, MDA intendeded to continue ground testing of the first ABL aircraft; conduct the first flight of the complete ABL Block 2004 weapons system; and proceed toward a lethality demonstration in 2004-2005. In April 2003 the MDA awarded a cost-plus-award-fee contract to Boeing in support of the Airborne Laser Block 2008 effort. The period of performance for this initial phase of the program is from April 2003 through March 31, 2004, MDA said. The value of this contract award is not to exceed $118 million, according to MDA.

The first YAL-1A is known as the Block 2004 aircraft. This aircraft was designed as a prototype rather than an operational asset. Although it will have a limited lethal capability for contingencies, much of the support equipment to generate the chemical laser's fuel at forward bases is not expected to be available until around 2006.

The second ABL aircraft - dubbed the Block 2008 - will contain a more powerful laser, incorporate other hardware and software refinements and have the support infrastructure to operate at forward bases. The higher-than-expected power output of the laser modules may mean fewer will be needed on the aircraft than originally thought.

To date, the program has been concentrating on activities associated with getting “first light” through six fully integrated laser modules, and integrating the beam control system. All Block 2004 efforts are focused on achieving a successful, live shoot-down of a ballistic missile during FY05.

In order to demonstrate system performance as soon as possible, the Block 2004 program will delay some integration and testing until after the ballistic missile shoot-down. For example, integration and testing of the Active Ranger System is now scheduled to occur after the shoot-down.

The program has also reorganized the High Energy Laser (HEL) Lethal Edge Irradiance characterization, reducing the number of tests and engagement geometries occurring prior to the ballistic missile shoot-down. This limits the amount of data available through FY05, for extrapolating ABL’s negation capabilities against other missile threat classes. HEL beam characterization flight tests will be re-planned to the degree possible after the shoot-down event. Characterization of the HEL beam should continue in the Block 2006 test program to increase understanding of ABL lethality.

A thorough lethality test program is planned in the Block 2006 program but is not completely funded. The plan addresses primary negation parameters and includes the procurement of about a dozen targets, their engagement flight tests, and the necessary preliminary lab and flight testing. The execution of this plan, combined with good HEL beam characterization, should result in a thorough understanding of ABL’s negation capabilities under a range of conditions and threats.