1. ASCMD,
4.3 AIR FORCE MISSILE DEFENSE R&D PROGRAMS
The committee did not have an opportunity to review all R&D programs sponsored by the Air Force that might be relevant to theater missile defense.
However, a number of committee members have had, in contexts unrelated to this study, extensive interactions with Air Force R&D programs, and they are aware that the Air Force is undertaking efforts in three areas:
• Improved sensors for TMD applications (e.g., improved performance of AMTI, GMTI, and electro-optical/IR sensors),
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• Improved BMC3 systems for TMD applications (e.g., weapon control systems), and
• Improved weapons for TMD applications (e.g., improved performance of air-to-air missiles, EW techniques, and laser weapons).
Because not all of the committee members had interactions with the Air Force R&D programs, only the programs that were briefed to the entire commit- tee by Air Force representatives will be covered here. These programs are relat- ed to laser weapon developments and are most significant in the context of the Navy’s NTW TBMD effort.
The Air Force’s BMD program is focused on the ABL project. The pro- posed ABL system will consist of a multimegawatt laser carried aboard a modi- fied Boeing 747 aircraft. The system is designed to engage TBMs during their boost phase at standoff ranges of several hundred kilometers. In theater, the ABL will not require penetration into enemy airspace and will be able to engage the shorter range threats. Nevertheless, it will possess a self-defense suite. Fur- thermore, although its primary mission will be missile defense, the system, by its nature, also opens opportunities for applications in other missions. These might include the following:
• The protection of high-valued airborne assets against surface-to-air missiles,
• The accurate determination of launch points, and
• The collection of postboost tracking data that would provide cues to the other BMD systems to enhance their performance.
The ABL program requires integrating a multi-megawatt COIL into the air- craft to kill boosting TBMs. The ABL laser system consists of three main segments:
• A laser segment to provide laser power;
• A beam control/fire control segment to acquire the target, align the laser, compensate for atmospheric distortion, and propagate the laser beam through the nose-mounted turret; and
• A BMC3 segment to provide surveillance, communication, planning, and central command and control of the ABL weapon system.
The turret assembly contains a 1.5-m-diameter primary mirror mounted on the nose of the aircraft. Six onboard infrared sensors will provide 360 deg of coverage to permit autonomous detection of boosting missiles. The aircraft will cruise at approximately 40,000 ft and thus be substantially above cloud layers.
The COIL radiates at a wavelength of 1.3 µ and is being designed to radiate multi-megawatts of energy so that it can heat missile structures to their failing point, causing a destructive kill of the missile.
If the development of the ABL is successful, it will prove to be a great asset to a theater commander-in-chief. It will have an engagement ability to destroy at least 20 enemy missiles. Depending on engagement geometry, atmospheric tur- bulence, and missile type, it could destroy up to twice that number or more.
With an in-air-refueling capability, the range and on-station endurance of a 747 implies that the availability of local in-theater basing will not be a major limita- tion of the ABL system. If the system performs as the Air Force projects—that is, as part of a tiered theater missile defense architecture operating in concert with various ground-based and sea-based systems—the ABL should provide a flexible, rapidly deployable response for expeditionary operations.
Although the committee believes that the development risks associated with the ABL are reasonable and that they are likely to be resolved successfully, some development risks do exist. They are as follows:
• The packaging and operation of the system on a 747 aircraft,
• Uncertainties related to optical propagation and beam spreading,
• The impact of countermeasures on the system’s lethality, and
• The false and missed alarm rates of the ABL’s autonomous target detec- tion system.
The Air Force has an active and well-funded effort under way to install and test the laser on a 747 aircraft. An important component of the research and test program deals with propagation and beam spreading, along with the problems associated with holding the beam on the most vulnerable part of the target.
The main operational issue that must be addressed is that the consumables used in the laser cannot be replenished on station. Therefore, any countermea- sure that increases the dwell time required for the laser to destroy the target directly decreases the capacity of the system. Coupled with the multiplier effect of the number of aircraft needed to ensure one aircraft continuously on station, this suggests that the mission capacity versus countermeasure trade-off is sig- nificant.
Assuming continued funding and no development delays, an airborne laser weapon designed to kill ballistic missiles in their ascent phase is planned for an initial operational capability between 2008 and 2010.
The committee was briefed on the use of a lower powered COIL laser on a low-flying aircraft for defense against cruise missiles. Such a system concept is not funded (nor should it be emphasized) and is not as important to the cruise missile defense problem as ABL is to the ballistic missile defense problem.
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