The Airborne Laser Anti-Missile Program

CRS Report for Congress
The Airborne Laser Anti-Missile Program
Updated February 18, 2000
Michael E. Davey
Specialist in Science and Technology
Resources, Science and Industry Division
and
Frederick Martin
(Consultant)
(An AAS/IEEE Congressional Fellow for 1998)

Congressional Research Service ˜ The Library of Congress

A^BSTRACT
This report describes technical issues and congressional options associated with the Air
Force’s attempt to build and install a multi-megawatt Chemical Oxygen Iodine Laser (COIL)
and a complex optical system to direct the laser to the target, in a modified Boeing 747 to
destroy short range missiles in their boost phase. As part of its FY2001 budget, the
Administration has proposed a significant restructuring of the ABL program which,
if approved by Congress, would delay the ABL’s first attempt to shot down a missile
from FY2003 to FY2005. The ABL program is currently in its Program Definition and
Risk Reduction (PDRR) phase, which is intended to produce a full-scale system, with a half-
power laser. The current estimated cost of the ABL is $11 billion, including $1.6 billion for
the PDRR phase. However, if Congress approves the restructuring of ABL, these costs will
increase. The report describes the major systems components, and reviews technical issues
associated with the three separate laser systems, the adaptive optics system (AOS) for
atmospheric compensation, and the nose mounted turret. The report concludes with several
policy options Congress may wish to consider regarding the future of the ABL program. This
report will be updated to reflect significant congressional actions or the achievement of ABL
programmatic milestones.

The Airborne Laser Anti-Missile Program
Summary
The Air Force is currently attempting to build and install a multi-megawatt
airborne laser (ABL) and a complex optical system to direct the laser to the target,
in a modified Boeing 747 to destroy theater ballistic missiles in their boost phase. As
an operational platform, the 747, along with its multi-megawatt Chemical Oxygen
Iodine Laser (COIL) is being designed to destroy missiles in the stratosphere above
40,000 feet (12 kilometers), within one to two minutes after launch, at ranges of up
to several hundred kilometers (km).
The 1991 “Gulf War” raised concerns about the destructive capacity that small
nations can possess in the form of short range missiles capable of carrying highly
destructive warheads. This capability motivated the U. S. military to seek an effective
means of defense against missiles of short to intermediate range, the so-called theater
ballistic missiles (TBM).
The ABL program is currently in its Program Definition and Risk Reduction
(PDRR) phase. The PDRR is intended to produce a full-scale system, with a half-
power laser. However, the FY2001budget proposal includes a significant
restructuring of the ABL program which, if approved by Congress, would delay the
ABL’s first attempt to shot down a missile from FY2003 to FY2005. Under the
current budget proposal, funding for the ABL program would be cut $903 million
between FY2001 and FY2005. The current estimated cost of the ABL is $11 billion,
including $1.6 billion for the PDRR. If the proposed restructuring is approved by
Congress, these costs would increase.
The Air Force contends that the ABL utilizes “mature” technology capable of
destroying enemy TBM at ranges up to hundreds of km. Others, including the Air
Force Scientific Advisory Board, have characterized ABL key technologies as
“experimental.” The congressionally mandated Independent Assessment Team (IAT)
identified a number of technical challenges facing the ABL including laser power
generation, laser beam pointing and tracking capabilities, prediction and compensation
of atmospheric distortion, and the use of enemy counter measures to defeat the ABL.
The IAT also indicated that the Air Force revised PDRR testing plan to address these
challenges should “reduce the risks and narrow uncertainties of the ABL program.”
Congressional concerns about the ABL have been expressed since its inception.
In FY1999 these concerns centered around two main issues. The first is the belief
that the Air Force had not adequately demonstrated the feasibility of the necessary
technology to begin “such significant investments” needed to complete PDRR. And
second, that testing necessary to make important decisions about the technological
viability of the ABL program will not occur until FY2003, just prior to ABL entering
EMD, one year after the Air Force is scheduled to order a second unmodified 747.
The Air Force conducted a number of additional tests in 1999 to address a number of
these congressional concerns. The results of these tests are discussed in the report.

Contents
Introduction ................................................... 1
A Brief History of Weapons at the Speed of Light.......................4
What It Takes To Build an ABL....................................4
Detecting the Missile.........................................8
The Chemical Oxygen Iodine Laser (COIL)........................8
Precision Tracking...........................................8
Adaptive Optics System (AOS)................................10
The Nose Mounted Turret....................................11
Systems Integration.........................................11
General Systems Operations......................................12
ABL Technical Challenges....................................15
BF/CF: Tracker and Adoptive Optics System (AOS)................16
COIL Power..............................................17
Atmospheric Turbulence.....................................18
The Nose Mounted Turret....................................19
Systems Integration.........................................20
Software Development......................................21
Field Operations and Life Cycle Costs...........................21
Congressional Concerns and Issues.................................22
Current Technical Issues.....................................22
The COIL................................................22
Beam Control / Fire Control..................................23
ABL Testing..............................................27
ABL PDRR Schedule.......................................28
Counter Measures..........................................29
FY1999 Authorization and Appropriations........................32
FY2000 Authorization and Appropriations........................34
Conclusion ................................................... 35

The Airborne Laser Anti-Missile Program
Introduction
Air Force Restructures the ABL Program
As part of its FY2001 budget, the Administration has proposed a significant
restructuring of the ABL program which, if approved by Congress, would delay the
ABL’s first attempt to shot down a missile from FY2003 to FY2005. Under the current
budget proposal, funding for the ABL program would be cut $903 million between
FY2001 and FY2005. The Air Force requested $148.6 million for the ABL in FY2001,
$92 million below the planned level of $241 million. Congress appropriated $309 million
for ABL in FY2000. The ABL is designed to shot down theater ballistic missiles during
their boost phase.
The $11.3 billion program is currently in its PDRR phase ($1.6 billion) and was
scheduled to move into an EMD program in March of 2003. If Congress were to
approve this proposal (which is likely to receive considerable opposition in both the
House and Senate), it is likely that the program would not enter EMD until after 2005.
Further, according to the Air Force, programmatic delays will result in significant cost
increases for the entire ABL program.
The Air Force has placed the ABL on its unfuded priority list (UPL) that is
submitted to Congress. This list consists of Service programs, in order of priority, that
the they would fund if Congress appropriated more for defense spending than originally
requested by the Administration. The FY01-FY05 ABL UPL request restores $873
million of the proposed $903 million reduction. The Air Force $241 million plan request
for ABL.
The PDRR plane has recently begun its 18 month modification to accommodate the
six module COIL and the 14,000 pound nose turret and related structure that will be
used in both ground and flight test of the modified ABL system. If the restructuring
program is implemented all of the major programmatic milestones dates, contained in
this report, will be delayed by a minimum of two years.
.
The Air Force is currently attempting to build and install a high powered airborne
laser (ABL) in a modified Boeing 747 to destroy theater ballistic missiles in their
boost phase. As an operational system, the 747, with its multi-megawatt chemical
laser is designed to destroy missiles in the stratosphere above 40,000 feet (12
kilometers) within one to two minutes after launch, at ranges of several hundred

kilometers. If the Air Force’s Program Definition and Risk Reduction (PDRR)¹
activities meet their technological expectations, a modified ABL is scheduled to
achieve its first shoot down of a missile in FY2003.
The 1991 “Gulf War”raised concerns about the destructive capacity of short
range missiles (often referred to as Scud missiles) capable of carrying highly
destructive warheads. The growing possibility that developing countries may be able
to deliver chemical, biological, or nuclear weapons has motivated the United States
to seek an effective means of defense against missiles of short to intermediate range,
the so-called “theater” missiles. Each of the three Services is developing theater
missile defense systems. The Army and Navy are developing five Theater Air and
Missile Defense (TAMD) systems (to counter lower tier, or short range missiles
within the Earth’s atmosphere and upper tier long range missiles above the Earth’s
atmosphere or in the upper atmosphere) under the Ballistic Missile Defense
Organization (BMDO). While the ABL program is managed and funded by the Air²
Force, it is coordinated with BMDO. From an operational perspective, it is designed
to be integrated with the other Services’ TAMD systems.
The ABL has several characteristics which are unique with respect to the other
TAMD systems. First, the ABL is designed to destroy its missile in the boost phase,
within approximately the first two minutes of flight. For reasons that will be
discussed in the report, unlike other TAMD weapons, the ABL laser is unable to
destroy a missile once the boost phase is complete. Second, the ABL will be capable
of detecting and locating the missile from the moment it is launched (under ideal
conditions, e.g. minimal cloud cover) and throughout the boost phase. While the ABL
is being designed to coordinate its effort with the other Services’ theater defense
activities, the ABL, would be capable of operating independently of the other
Services’ TAMD systems.
Third, the ABL also serves as a surveillance vehicle. Its precision tracking and
projection of target destinations of missiles and aircraft can be passed on to the Army
and/or Navy theater operations command for use with other missile defense assets.
Fourth, the ABL could be designed to attack other airborne threats such as aircraft
and anti-aircraft missiles, and ground base threats using optical sensors for detection
and guidance. Finally, given the planned mobility of the ABL, the Air Force contends
it can be deployed to an area or region of potential conflict within 24 hours and
quickly repositioned as the conflict shifts in direction or extent. Thus the Air Force

According to DOD the primary purpose of a PDRR is to demonstrate critical manufacturing¹
practices by gathering engineering data for the engineering, manufacturing and development
(EMD) phase and building a prototype in order to enhance program confidence by shooting
down several missiles at appropriate ranges. This involves examining alternative program
acquisition strategies in order to develop program costs, including total life cycle costs. A
successful PDRR should ensure that technology, manufacturing, and support risks “are well
in hand,” before moving into EMD.
For further details see: Congressional Research Service, Theater Air and Missile Defense:²
Issues for Congress, by Robert Shuey and Lisa Meyer, CRS Issue Brief 98028, updated
regularly.

views the ABL as a highly flexible weapon that can also help attain its core mission
of securing and maintaining air superiority during conflict.
The actual success of a “directed energy” weapon depends on the killing range³
of the weapon, in this case a high powered chemical laser. Other critical parameters
of the ABL are the accuracy with which the laser can be pointed, the length of time
the laser stays on target, and the energy the laser can place on the missile. While the
Air Force has a long history in experimenting with laser weapons, the ABL would be
the first fully integrated computer controlled system for target detection, tracking, and
firing a multi-megawatt laser as an anti-missile weapon.
Three advances in technology since the early 1980s have increased the
possibility that a successful ABL can be built: 1) the increased power and speed of
microprocessors needed for the evaluation of complex algorithms (mathematical
formulas) for systems operations and control; 2) steady improvements in the
development of adaptive optics to insure the arrival of the sufficient laser power on
the target; and 3) the steady improvements in the development of an efficient, light
weight chemical laser. Without all three of these developments this program would
not now be feasible. However, there remain some complex technical challenges that
must be overcome in order for the ABL to be built and successfully tested.
Responding to congressional concerns and the recommendations of the
congressionally established Independent Assessment Team (IAT), the Air Force added
risk reduction activities and significantly expanded the PDRR test program, and
revised its estimates life-cycle cost of the ABL program. This estimate includes $1.6
billion (a $300 million increase) for the current Program Definition and Risk
Reduction (PDRR), $1.1 billion for the engineering and manufacturing development
(EMD) phase, $3.6 billion for the production phase, and $4.4 billion for 20 years of
operations and support. If the Air Force’s PDRR activities meet its technological
expectations, a PDRR prototype ABL is scheduled to achieve its first shoot down of
a test missile in late FY2003. If this shoot down is successful, the program will move
to a two year EMD program in FY2004, assuming that the long lead items have been⁴
ordered.
The report begins with a brief history of laser research in the Air Force. This is
followed by a description of the major subsystems that make up the ABL. Next the
report provides an overview of the technical and programmatic challenges confronting
the ABL program. The paper concludes with a discussion of congressional issues and
options regarding ABL.

A directed energy weapon kills its target by delivering energy to it at or near the speed of³
light. Includes lasers and particle beam weapons.
Spending estimates from official Air Force documents.⁴

A Brief History of Weapons at the Speed of Light⁵
The Department of Defense (DOD) has been exploring the possibility of using
lasers as both offensive and defensive weapons since the early 1960s. By the mid-
1960s all three Services had established task forces to study the use of lasers as
potential future weapons. In the early 1970s, the Air Force contracted with General
Dynamics Corporation to build an Airborne Laser Laboratory (ALL) and with Hughes
Aircraft to design and build a Airborne Pointer Tracker laser. In 1983, after nearly ten
years of research, the Air Force announced that the ALL had managed to “destroy⁶
or defeat” five AIM-9 Sidewinder air-to-air missiles and a BQM-34 drone.
These tests did demonstrate that a high-powered laser (but with much less
power than the ABL laser) mounted in an airplane could destroy a missile. Further,
the ALL use a human to initiate the separate computer controlled pointing and
tracking system, shot at a range of only 10 km, and, did not utilize atmospheric
compensation to correct the distortion of the laser beam. The table below presents
some key dates in the Air Force’s quest to develop an airborne laser.
What It Takes To Build an ABL
The ABL is a complex system of state-of-the-art technologies. It utilizes three
powerful lasers, a variety of infrared sensors, and delicate precision optics. Powerful
computers and complex software control its operation. The ABL is composed of
several major subsystems which address the functional requirements of detection,
tracking, aiming and adjusting the lethal laser beam, and destruction of the missile. A
final challenge involves integrating the subsystems into a working weapon on board
a specially modified aircraft.
The term ABL designates an aircraft carrying a multi-megawatt laser and a⁷
complex optical system to direct and “refocus” the laser beam, as it travels through
the atmosphere, towards the target. The ABL system is designed to cruise in a safe
Table 1 Brief History of Air Borne Laser
YearActivity

1970'sAirborne Laser Laboratory (ALL) experiments with a CO Laser testing²

& early 1980'svarious directed energy possibilities.

1983ALL demonstrates the destruction of a missile with a laser, at short range.

1980'sLaser radar tracking widely used for short, horizontal ranges.

Table developed by CRS, information provided by the Air Force.⁵
Air-to-air missiles are aircraft mounted missiles designed to shoot down enemy airplanes.⁶
The potential power level of the COIL laser is classified information.⁷

1980'sAdaptive optic systems actively researched and demonstrated in the
laboratory, leading to applications in observational astronomy.
1980 - 1985 MIRACL/SLBD a ground based Deterium Floride laser destroys a variety of
missiles at short ranges.

1987COIL laser module produces 25 kW output at 1.315 micrometers.

1993 - 1995Tests, measurements, and analysis to develop techniques for adaptive optics to
compensate for air turbulence ( i.e. ABLEX 1993, ABLE-ACE 1995, et al).

1996COIL demonstrates high power capability in one module.

1996Active tracking of boosting missiles demonstrated at short ranges (Black
Brant Active Track).

1997MIT/LL demonstrate closed loop tracking and AOS beam compensation on⁸

static target (Firepond Project) at 5.4 km. Demonstration design scaled to

200 km at a bandwidth of 100 Hz.

1997Boeing successfully tests modified 747 scaled configurations for the nose
turret and exhaust manifold in a wind tunnel.
1998, MayLockheed Martin (L-M) tracking, laboratory tests demonstrate tracking to

100 nano-radian (0.02 arc seconds of angle) accuracy.

1998, JuneAuthority to Proceed-1 (ATP-1), OSD and AF give authority to proceed with
some conditions.
1998, JulyHigh power laser tests of exterior coatings to prevent heat damage of
representative deformable mirror are successful.
1998,COIL tested with new, light weight components, achieving 110% of required
Septemberpower at a weight of 1410 kg.

Massachusetts Institute of Technology, Lincoln Laboratory ⁸

zone of a combat theater, behind friendly lines, where it can detect, track, and fire the
high powered laser to destroy theater ballistic missiles (TBM) launched from the
enemy territory. For technical reasons, missile destruction must take place during the
boost phase of the missile and above the clouds, at elevations in excess of 40,000 feet.
Below this altitude atmospheric visibility can be obscured by clouds, and the
atmosphere has a great deal of turbulence. These two conditions can hinder the
detection and precision tracking of the missile early in its boost phase, thereby
limiting the lethality of the chemical oxygen iodine laser (COIL).⁹
One of the advantages of early destruction of the missile is that the warhead
with its payload is likely to fall onto enemy soil. Older TBMs (e.g. scuds) have a
range of about 200 km- 300 km, while new TBMs have ranges that can exceed 1,000
km, depending on the payload, and the material the missile is made from (i.e.
aluminum or steel).
As previously indicated, the ABL is designed to be completely autonomous in
that it can detect, locate and destroy a missile without assistance. Figure 1 shows a
layout of the ABL in the aircraft. The multi-megawatt COIL laser is positioned in the
rear portion of the fuselage. The lethal beam travels in a helium filled tube to the
beam control unit in the nose of the aircraft. The beam control unit compensates
(focuses) the beam and projects the beam through a window in the nose of the
aircraft, directing it at a target hundreds of kilometers distant. In addition, there are
infrared sensors and trackers for detecting and locating additional missiles while the
ABL is engaging an identified target.
The ABL will have to carry the chemical laser fuel on board the aircraft (see
figure 1). The Air Force estimates that the current laser fuel carrying capacity will
allow the high powered laser an estimated 20 to 40 shots at a number missiles, before
requiring the plane to return to base for refueling the weapon. However, capacity
could be less than 20 to 40 shots depending on the duration of each shot, which is
expected to last a number of seconds depending on range and atmospheric
disturbances.
The following sections describe the major subsystems that comprise the ABL.¹⁰

Chemical lasers produce power as a high-energy beam of concentrated light derived from⁹
chemical reactions, in this case between excited oxygen and iodine atoms.
Most of the following descriptions are taken from official Air Force documents.¹⁰

Beam Control/Fire Control
Key Design Highlights
^{Tracking & AOS}^{Mid-optical Bench}
^{Beam Tube}^Lasers
^Foward^{COIL Laer Module (6)}^{ABL Personnel}
^Bearing^{Aft Optical Bench}
^Support
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^Laser^{System E/E Racks}^Bulkhead^Turret
^{COIL Laser}^Electronics^Window^Assembly
^Fuel^{Main Optical Bench,}
^{Tracking and AOS}^-Nose-mounted turret for lowest optical
^Components disturbance - wind tunnel validated
- Adaptive optics for atmospheric
compensation - brassboard validated
- Common Path/Common Mode sensing
and controls - experimentally validated
- Vibration isolation data - flight validated
- ATP/Fire Control algorithms optimized -
anchored models, ground test validated
Figure 1: ABL System Configuration in a 747F-400 Boeing Aircraft
Source: Air Force Briefing at Lockheed-Martin, October 28, 1998

Detecting the Missile
First, the missile must be detected and located. This may take place with either
on-board sensors designed to detect the heat radiated by the exhaust plume from the
rocket, or, alternatively, a satellite or other surveillance vehicles that can detect and
locate the firing of a rocket in the theater of action or war zone.
The ABL aircraft will carry several Infrared Search and Track Sensors (IRSTs),
which will allow the tracking of more than one missile launch. IRSTs is used to detect
signal characteristics of hot missile exhaust. Once the launched missile has been
located, these IRSTs establish an initial coarse track of the missile trajectory. As
information on the trajectory accumulates it will be conveyed to the main ABL
computers. The detection and coarse tracking equipment employs mature
technologies which have been used on military aircraft and satellites for a number of
years.
The Chemical Oxygen Iodine Laser (COIL)
The COIL is a dual-line, multi-module laser operated as a single, unstable
resonator (continuous beam), with the cavity mirrors installed midship and a pair of
turning prisms at the rear to complete the beam path (see Figure 1). Located near the
exit mirror, a “deformable” mirror cleans up the beam profile as it leaves the laser.
Chemicals for fueling the laser, along with the plumbing are stored in the central and
rear portions of the fuselage.
According to the Air Force, the COIL laser provides sufficient power to destroy
missiles up to several hundred kilometers under various atmospheric conditions. The
initial PDRR demonstration aircraft will use six lasers (2 rows, 3 lasers in each row)
to producing more than a megawatt (MW) of power. The actual operational system
will have 14 lasers (2 rows 7 lasers in each row) which will produce several
megawatts of power (see Figure 2). This is a significantly higher level of power than
has been produced with a continuous or semi-continuous ground based chemical laser.
Lasers are inherently inefficient devices, in that they convert only a small fraction of
the input energy into laser light energy; most of the energy is dissipated as heat. The
limited availability of electrical power on an aircraft precludes using electrically
powered lasers of the megawatt size. The chemical laser uses the energy resulting
from the chemical reaction of several chemicals to power a laser without massive use
of electrical power. The COIL chemical energy is supplied by the reaction of
hydrogen peroxide and chlorine. To obtain its destructive power this laser must
sustain high power output for a number of seconds and produce a high quality beam.
Designing and constructing the high power laser for installation aboard an aircraft are
some of the more difficult engineering challenges for this project.
Precision Tracking
This section and the following two sections on adaptive optics and the nose
mounted turret describe the Beam Control/Fire Control system (BC/FC). Located
forward in the airplane is the Beam Control/Fire Control system comprising a

ABL System Design
Figure 2: ABL System Design from PDRR to EMD
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complex optical system which tracks the missile, the atmospheric compensation
subsystem, and the 1.5 meter laser beam steering mirror, mounted in the rotating nose
turret with the 1.74 meter window (see Figure 2).
The ABL system uses the coarse tracking data from the IRSTs sensors to initiate
the precision tracking system to direct the lethal laser. The tracking unit operates as
a separate laser radar system. A powerful, pulsed laser is directed at the target. Some
of the light is reflected off the target missile and returns to the tracking unit on board
the airplane. A detector collects this light and a computer processes the sensor signals
to form an image of the missile. The tracking laser locks onto this image to track the
trajectory of the missile. This is a time critical operation. The ABL must lock onto the
missile within several seconds depending on the range of the missile.
The ABL system requires this tracker to locate, within tens of centimeters, the
front of the missile at distances of several hundred kilometers. The need to
concentrate the energy from the lethal laser onto the body of the missile drives this
high precision requirement. Moreover, when the tracking system first locks onto the
missile it may only be traveling at mach 1. But, by the time the system is ready to fire¹¹
the COIL laser the missile will be traveling at mach 2 or faster and continually
accelerating until burn-out or destruction.
The tracking subsystem consists of a number of mirrors including the output
mirror, 1.5 meters in diameter, that directs the lasers at the target. The mirrors are
mounted on a special bench that keeps them in precision alignment. The COIL's beam
is directed through some of the same optics to the missile. The tracking laser has a
slightly different wavelength than that of the COIL and thus the tracking laser
operates independently of the COIL.
Adaptive Optics System (AOS)
As the COIL beam propagates through the atmosphere to the target missile it
encounters turbulence, water droplets, ice crystals, and temperature variations which
can distort the beam and cause it to lose focus on the missile (see Figure 1). A very
common phenomenon, such distortion can be seen by viewing a distant object through
air rising off hot pavement. If the COIL beam encounters atmospheric turbulence it
will, if uncorrected, lose focus and become ineffective in destroying the missile. The
purpose of the AOS is to compensate for the beam distortion to ensure the beam has
sufficient coherent energy to destroy the missile.
Here is how it works. A separate "beacon" laser generates a string of rapid light
pulses which scatter off the missile. In the same manner as the tracking laser, the
AOS collects and analyzes the scattered pulses to measure the distortion produced by
the atmosphere. The AOS utilizes this measurement to reshape a special computer
controlled deformable mirror, which distorts the outgoing COIL beam to compensate
for the distortion resulting from atmospheric turbulence. Experience with
astronomical applications and other laboratory studies have shown that this beam
compensation will focus more energy on the missile target, maintaining its lethality

Mach 1 is equal to the speed of sound or approximately 1150 feet per second, at sea level.¹¹

instead of losing it because of dispersion in the atmosphere. The ratio of the focused
power in the actual beam to that of a perfectly focused beam is known as the strehl
ratio (SR).
However, it is important to note that if the initial beam produced by the COIL
is insufficient in terms of power and/or coherence, the AOS will not be capable of
“correcting” what the COIL was unable to produce initially.
The Nose Mounted Turret
Another crucial component of the ABL is the approximately 12,000 pound turret
in the nose of the modified 747 aircraft. The turret carries both the 1.74 meter
window and the 1.5 meter pointing mirror. The latter is mounted on a gimbal that
rotates the mirror to point the laser beams at the target. The turret field of regard
covers the forward hemisphere of the aircraft, and the aft portion almost to the
wings.The nose window is a critical optical component for ABL All three laser
beams, the passive image of the missile plume for the plume tracker, and the return
signals for the fine tracker and the atmospheric compensation subsystem, pass through
this window.
Aside from purely structural engineering, the window has several system level
requirements: 1) the shape, location, and installation must minimize the exterior
boundary layer turbulence around the window so as to minimize optical distortion in
the COIL beam; 2) beam distortion (birefringence) due to mechanical and thermal
strain in the window must be minimized; and 3) there must be low absorption and
scattering of the laser light as it passes through the window and is reflected off the
target back to the ABL optical system.
Systems Integration
Boeing is the prime contractor and is responsible for overall management of the
ABL program, including the significant challenge of systems integration. Boeing has
developed plans to modify a 747-400 aircraft for the ABL. Besides accommodating
the COIL and the BC/FC, two major components of Boeing’s aircraft modifications
are: 1) the rotating nose window which also carries the 1.5 meter pointing mirror,
and 2) the laser gas exhaust system. Since the interior of the aircraft, will be noisy,
particularly when the lasers are operating, Boeing is investigating the need for
enhanced communication equipment among the flight crew and ABL operators.
The ABL computer controlled command and control center must coordinate all
the activities of the three lasers on board. This includes acquiring the initial
information on the location of the missile launch, initiating the pointing laser, the
precision tracking laser and the subsequent follow on activities of the tracking laser
beam adaptive optics system (AOS), concluding with the firing the COIL. All of this
must take place in 30 seconds or less as the missile accelerates to high velocity in its
boost phase.
To aid in the systems integration tasks, Boeing is using the CATIA, a
sophisticated computer design tool used in building its commercial aircraft. This

computer design tool allows Boeing, or any other ABL contractor, to make a
“blueprint” change in one ABL subsystem that will automatically be reflected in other
subsystem drawings, if necessary. The software engineering makes use of the existing
Boeing Open System Architecture and all builds are tested in a virtual ABL facility
at Boeing.
General Systems Operations
Cruising in a safe fly zone, probably behind the battle lines, the ABL is capable
of operating as an autonomous platform designed to detect, target, and destroy
theater missiles aimed at local military assets. ABL relies on either its on-board
detecting equipment, or standard airborne or satellite detection equipment now in
service to detect a missile launch. Once located, the ABL initiates its laser radar
tracking subsystem to lock on to the moving missile and track its position to high
accuracy. The AOS, utilizing a second laser, sends and receives signals from the
target to measure the atmospheric turbulence in the path of the laser beams. The
AOS converts these measurements into corrections that help “re- focus” the power
of the COIL beam on the target. In a matter of seconds, the multi-megawatt, COIL
is focused on the missile for several seconds, depending on the distance to the target,
to destroy the missile.
Below an altitude of 12.5 kilometers (about 41,000 feet) atmospheric visibility
can be obscured by clouds and atmospheric turbulence. These two conditions would
greatly hinder the detection and precision tracking of the missile early in its boost
phase, and they can limit the lethality of the system. Consequently, the general
consensus among the engineers and the Air Force is that the best time to attack the
missile is as it enters the stratosphere, above the clouds where there is less
atmospheric turbulence, and before the boost phase terminates. Notably, the latter
part of the boost phase also coincides with large acceleration and stress on the missile.
The ABL is designed to destroy the missile during the boost phase because: 1)
the rocket is highly vulnerable to disruption while it is under power; 2) it is relatively
easy to detect and track its exhaust plume; and 3) the laser beam destroys by
destructive heating of the stainless steel missile body.
Figure 3 displays the characteristic features of a typical short range missile. The
main body of the missile, between the conical warhead and the engine at the base of
the missile, is mostly fuel tanks. The warhead is about two meters in length, and the
engine, comprising turbo pumps and a combustion nozzle , occupies about two meters
at the base of the missile. At take off, 75-80% of the weight of the rocket is fuel
contained in a thin metal casing. The six to eight meters of the main body carries the
fuel, oxidizer, and a guidance system; it is considered the most vulnerable region for
the laser. Focusing the tracking laser on the warhead provides the information
needed to guide and focus the lethal laser

[6] Because an enemy missile may
have chemical or biological sub-
munitions, a goal of boost-phase
defense is to have it fall as close as
possible to the attacker’s territory.
As shown here with the Iraqi al-
Husayn as an example, the earlier a
missile’s thrust is terminated, the
shorter its range.
Figure 3: Typical short or medium range missile
Source: The Airborne Laser, G. Forden, IEEE Spectrum, September, 1997

on the missile body in an effort to penetrate one of the fuel tanks. As the laser heats
the missile casing to a high temperature, the combination of internal fuel pressure and
axial stress on the missile from the thrust of the engine may cause one or more of the
following:
<The internal fuel pressure may rupture the tank and the fuel will leak out.
At a minimum, the rocket would prematurely terminate its boost phase and
fall short of its target destination.
<The launching forces on the rocket under acceleration may collapse the
body of the rocket causing it to fragment and the warhead would veer off
and possibly fall in the vicinity of the launch site.
<Less likely, leaking fuel may detonate and destroy the rocket and its
warhead.
It is important to note that destroying the missile does not automatically destroy
the warhead; its ultimate fate is largely speculative at this time. The reason for this
is in the dynamics of launching a ballistic missile, which is similar to firing a rifle. The
launch begins with an explosive burst of energy for a minute or two, the boost phase,
followed by four or five minutes of coasting to the target. The rocket launches
vertically. About one-third of the way through the boost phase it has attained the
velocity of mach 1 and an altitude of more or less five kilometers. At this point the
rocket thruster shifts to aim the rocket at the target. The boost phase continues for
another 30 or 40 seconds at which point the missile is traveling many times the speed
of sound and is climbing through an altitude of 30 or 40 kilometers (18-24 miles). The
missile or warhead coasts on the remainder of its trajectory to the target. Some long
range ballistic missiles may have the capability of small mid-course corrections and
some detach the warhead from the rocket at the end of the boost.
Table 2: Approximate Values for SCUD Missiles Currently Fielded¹²
Parameter SCUD-A SCUD-B SCUD-C/ NODONG
al-Husayn
Length (m)11.2511.2511.2515.5
Diameter (m)0.880.880.881.3
Range (km)3003005001000
Payload (kg)9859857001000
Fuel Fraction0.740.740.770.80
Boost Time (sec)707087.570*
No. of Engines1114
* Others, including Boeing, estimate a considerably longer boost phase.

Table developed from data in, Analysis of the North Korean NoDong Missile,¹²
Wright & Kadyshev, Science & Global Security, Vol 2, N. 4, 1994; various articles
in IEEE Spectrum, September 1997; and private communication with Geoffrey
Forden, at the Congressional Budget Office.

All of the above launch estimates scale in time with the range of the missile as
indicated in Figure 3. A scud type missile going for a target at 100 kilometers arrives
in two minutes with a boost phase of 30 or 40 seconds. However, at 600 kilometers
the missile arrives at the target in six or seven minutes, with a boost phase of 70 to 90
seconds. Table 2 lists the principal attributes of the missiles currently in the field.
Also, it is possible to reduce the payload in order to obtain a marginal extension of the
range.
The Air Force also sees the ABL performing other defensive and offensive TMD
missions in the theater operations. Besides destroying the missiles, the Air Force
contends ABL could track them with high precision providing essential information
to the Army and Navy terminal defense operations and warn the target areas of the
impending attack. The Air Force is currently analyzing the potential of ABL to defeat
airborne threats (i.e. aircraft and missiles) for self protection and the protection of
other high value airborne assets in the immediate combat area.
There are many thousands of older SCUD missiles deployed around the world
with a range of 300 km or less, which, according to the Air Force, the ABL is well
designed to attack and kill. While some critics consider that long range missiles will
be inaccessible to the ABL, the Air Force contends that the ABL could provide an
additional capability against these missiles and essential information on their
trajectories.
ABL Technical Challenges
As previously noted, the basic requirement for the ABL is to destroy a missile
from a range of several hundred kilometers, within a couple of minutes after launch.
At shorter operational ranges ( distances less than half of the expected ABL
operational range) it is likely that the Air Force can build an airborne laser system¹³
that would knock down a missile shortly after it was launched, under reasonably ideal
conditions. But can a system be built that will deliver energy to a missile at ranges of
several hundred km sufficient to destroy the missile? This is the essential question
that defines the system's efficacy. Why is the range parameter chosen? Although the
Air Force emphasizes the existence of thousands of short range SCUD missiles
scattered around the world, Table 2 shows an evolving trend towards longer range
and high thrust missiles for theater operations. This implies that either the ABL must
penetrate into enemy territory or destroy the missile from a long range. In addition to
range, the lethality of the ABL during combat depends on other parameters such as
the variety of atmospheric conditions in which it will operate, the variety of counter
measures that could be employed, and the system’s ability to respond to random
events, such as the launching of several missiles simultaneously.
The following sections examine performance estimates and technical challenges
for the major subsystems, as well as overall systems integration. The analysis is based
on basic scientific principles and information on relevant technologies found in the
open literature. The objective of the analysis is to determine the extent to which a

Because of classification concerns, specific operational distances of the COIL can not be¹³
revealed.

system is capable of destroying a missile in its boost phase at ranges of up to several
hundred kilometers.
BF/CF: Tracker and Adoptive Optics System (AOS)
As part of the beam control, fire control (BC/FC) system, the tracker and the
adaptive optics system (AOS) uses relatively new technology that has been widely
implemented in modern astronomy but has never been employed with high power
lasers such as the COIL. The Air Force has performed a number of experiments on
AOS components to determine how atmospheric turbulence affects the propagation
of a laser beam. One such experiment (The Firepond Experiment) involved a short
range (5.4 km), closed loop tracking test on a static target at the MIT Lincoln
Laboratory which demonstrated that the strehl ratio (SR--level of beam coherence)
for an uncompensated beam can be increased by a factor of four with an AOS. This
demonstration simulated the ABL conditions for a range of 218 km in the
stratosphere. It is also important to note that the target was not moving.
One of the key components of the AOS is the deformable mirrors which
modulate the laser beam to compensate for atmospheric distortions. The final AOS
optics bench will utilize three 30 cm deformable mirrors with 261 computer controlled
actuators. A 10 cm version of this mirror, with the appropriate number of actuators
and special optical coating to prevent the mirror from over heating, has been built and
tested at laser power levels exceeding those expected in the fully operational system
ABL.
A working model of the tracking system has been tested at both the Lincoln
Laboratory and in the Lockheed Martin (LM) laboratory. According to Lockheed
Martin, it utilized simulated atmospheric turbulence and achieved the required
tracking accuracy specified by the Air Force's ABL functional requirements. Both the
AOS and the tracking system are using an electron beam charged couple detector
(EBCCD), a relatively new technology, for a high efficiency, low noise imaging
detector. There will be two of these EBCCD sensor units on the ABL, one for the fine
tracker and one for the wavefront sensor.
Despite the success of the Lincoln Laboratory test, the Independent Assessment
Team (IAT) indicated that atmospheric compensation has not yet been demonstrated¹⁴
at operational flight altitudes. The IAT report noted that while the initial detection of
the missile launch plume should not be difficult, the steps leading to the destruction
of the missile will be very challenging. Once the missile has been detected, the ABL
pointing and tracking lasers must “acquire and measure the distance to the apparently
small, dim target with a ranging laser; and then while maintaining very tight jitter
control, precisely place and hold on the missile two medium-power laser illuminator

As Part of the FY1999 Defense Authorization Act, Congress directed the Secretary of¹⁴
Defense to charter an Independent Assessment Team to review the technical and operational
aspects of the ABL program.

beams, or, tracking beams (that will generate returns that might be noisy and weak)
and a turbulence compensated COIL laser beam.”¹⁵
While the Air Force ABL officials are confident that the pointing and tracking
lasers will meet operational requirements, others in the Air Force, as well as the other
two Services, are concerned that the tracking laser may not be capable of tracking
theater ballistic missiles (TBM) at the longer operationally required distances. The
IAT has recommended that the AF conduct more rigorous dynamic testing (using
moving surrogate targets, including airplanes and other appropriate targets) in order
to gather more data on the operational effectiveness of the pointing and tracking
lasers.¹⁶
COIL Power
Once the target has been acquired, the COIL beams high power out the turret
window and onto the target. The energy deposited on the target causes the missile
casing to heat, and when the local temperature reaches the yield (destructive)
temperature for the metal, the internal stresses on the casing will cause it to fail and
the missile will break up. The success of the COIL is critical to the future of the ABL
as currently designed. An airborne laser of this magnitude has never been built. The
four major design drivers are: weight, size, power, and beam quality. In September
of 1998, a single laser module with the appropriate size required for the aircraft, and
flight-weighted to 3104 pounds (1410 Kg), was tested to better than 110% of design
power. From this test, the engineers have initiated some design improvements to be
implemented for the next version of the flight-weighted COIL.
However, a recent General Accounting Office (GAO) report questioned the
validity of the COIL power and quality measurements for two reasons. First, the AF
tested a flight weighted COIL that contained some key components which were not
representative of the COIL that will be deployed in the operational ABL. Second,
while the AF indicated that beam quality was satisfactory, the AF did not “fire the
laser” and simultaneously measure beam power and quality. Although the AF
measured output power directly, beam quality was estimated using software models.¹⁷
While it is not always possible or practical to “hot” measure the beam quality of a high
energy laser, using software models to estimate beam quality for a flight weighted
laser that has never been fired raises obvious concerns. AF representatives have noted
that their approach for measuring power and quality complies with scientifically
accepted methods for estimating power and beam quality during the testing and
development of a high energy lasers. The Chairman of the IAT, Thomas Marsh
indicated that he had confidence in the Air Force’s test results of the COIL.

Assessment of Technical and Operational Aspects of the Airborne Laser Program. March¹⁵

9,1999. Secretary of Defense comments on IAT report, P. 7.

Report of the Airborne Laser Program Independent Assessment Team. February 1, 1999.¹⁶
P. 5.
General Accounting Office. Defense Acquisitions, DOD Efforts To Develop Laser Weapons¹⁷
for Theater Defense. GAO/NSIAD, 99-50. March 1, 1999. P. 7.

The Air Force not scheduled to “hot” test the entire PDRR laser sub-system (i.e.
all six modules) for power and beam quality until July of FY2002, only 14 months
prior to the first scheduled lethal intercept in late FY2003. For the COIL to destroy
missiles at hundreds of kilometers it must produce a beam of exceptional quality. If
the beam quality is not sufficient, the COIL may not be able to deliver enough energy
on the target required to cause the missile to fail during the boost phase.
Based on general scientific principles and estimated laser power levels, beam
compensation factors, and the rate of metal heat absorption, CRS has estimated the
time it takes to locally heat the missile casing to the elastic (destructive) yield
temperature. These estimates are also based upon the range values extrapolated from
the ABL experiments at the MIT Lincoln Laboratory in 1997.
These estimates suggest that at the shorter operational ranges, the ABL, if it
operates as advertised, is likely be effective against TBM. This estimate is based on
remaining boost phase times for 2 mm thick exterior steel casing of the missile .¹⁸
However, at greater operational ranges for similar casings, the time required to
destroy the missile may exceed the time left in the boost phase. Given these potential
operational limitations, it appears that a fully functional ABL system at longer
engagements ranges could be vulnerable to counter measures. For example, a counter
measure which lowered the return signals for the tracking and AOS could cause the
COIL beam to wander and defocus, and increase the dwell time to longer than the
boost phase time. Moreover, if more than one missile is launched at the same time,
these estimates suggest that a single ABL may not have the time to engage both
missiles at longer operational distances. However, it is important to note that,
according to the AF Air Combat Command, ABL exceeds operational range
requirement for all classes of scud missilies.
Atmospheric Turbulence
As mentioned above, turbulence in the lower atmosphere (below 12.5 km) will
weaken (attenuate) and defocus the laser beams. The Air Force has devoted
considerable effort estimating and correcting for this attenuation. The primary
approach will be to try to engage the missile above the troposphere utilizing the AOS
to compensate for beam distortion (approximately 12.5 km, above 40,000 feet).
Below 12.5 km, the Air Force will apply the AOS to the COIL laser beam to
compensate for atmospheric defocusing. Based on the earlier work at Phillips
Laboratories, the gathering of atmospheric turbulence data (ABLEX and ABLE-ACE
tests), and the 1997 Lincoln Laboratory's Firepond experiment, the Air Force is
confident that the AOS will meet its basic operational requirements for the ABL.
The IAT noted that the ultimate value of the ABL depends on actual turbulence
to be at or below current AF estimated values. However, as noted by the IAT, much
of the AF’s current turbulence estimates are derived primarily from non-optical
measurements in regimes that may not be representative of the anticipated laser beam
path of the proposed operational system. The IAT recommended that “the AF

The details of the estimates and potential time frames for destruction based on missile¹⁸
distances are classified and can not be discussed in the report.

undertake a comprehensive atmospheric measurement program under conditions that
more accurately represent the operational environment of the ABL.” ¹⁹
The Secretary’s response to the IAT findings also noted “that turbulence in
excess of the design specification along the slant path between ABL and its intended
target can reduce ABL’s maximum lethal range and increase dwell times, even at
lesser ranges.” The complication is that there appears to be no clear method for
estimating turbulence levels along a slant path “to a particular threat location at a²⁰
given point in time.” The AF will collect more turbulence data in order to develop
tactical options for addressing this issue.
Further, even when operating above the troposphere, at greater operational
distances, the curvature of the Earth causes a portion of the laser beam to pass
through the troposphere, introducing that turbulence into a portion of the beam path.
Consequently, it is likely that at greater operational distances the laser beams will
sometimes encounter atmospheric defocusing and attenuation, and may not have
enough time to destroy the missile in its boost phase.
To address OSD and congressional concerns about the ability of the AOS to
track and compensate for atmospheric turbulence, the Air Force to accelerate a series
of tracking and illumination tests from North Oscura Peak (NOP) in New Mexico.
Using both fixed and moving targets, out to a range in excess of 50 km, a series of
comprehensive tests on tracking and the AOS, focusing on beam compensation and
scoring will be conducted to validate the operation of these crucial BC/FC
subsystems. These tests will scale to ABL engagements of 300 to 400 kilometers in
range. However, its important to note that the AF will be utilizing a surrogate laser
and replica of the BC/FC system, not the actual hardware that will fly in the ABL.
The Air Force conducted additional AOS testing at NOS in July of 1999 in
which a scaled laser was aimed at a target 50km away. The test facility included a
functional equivalent of the AOS scheduled for the ABL with scaled mirrors and
power to replicate an ABL engagement of a target over a distance of 300-400km. At
the conclusion of these tests, the Air Force reported that the laser was able to place
sufficient energy on the target with atmospheric conditions three times worse than
the ABL is expected to operate in.
The Nose Mounted Turret
This nose turret is made with light-weight composites, carrying the 1.74 meter
window and a 1.5 meter mirror, two heavy glass objects (see Figure 1). The turret
rotates up to 260 in order to direct the lasers toward the target. Weighing⁰
approximately 12,000 pounds, the turret attaches to the aircraft from one end with a
large ring bearing. That it cantilevers from a pressure bulkhead on the aircraft poses
an interesting structural problem. The azimuth overroll gimbal for the turret’s field
of regard covers the forward hemisphere and aft almost to the wings of the aircraft.

Op Cit. Secretary of Defense response to IAT report, P. 6.¹⁹
Op Cit. Secretary’s response. P. 9.²⁰

Moreover, the turret is shaped and designed to minimize the turbulent boundary layer
on the window to preserve the integrity of the laser beam. This is probably a unique
structure for an aircraft, somewhat reminiscent of machine gun turrets on World War
II bombers.
To address these concerns, a tenth scale model of the turret was built and tested
in a wind tunnel to determine how to control the boundary layer to eliminate
turbulence that would de-focus the laser beams. A scaled, 20 inch version of the
window was made to verify the manufacturing process and the quality of the final
window. As long lead items, the initial blanks for the window and mirror have been
ordered, and fabrication of the window has begun. The turret, window, and mirror
assembly are not scheduled to be incorporated into the integrated COIL, tracking, and
AOS testing until the second quarter of FY2001.
Systems Integration
One of the most demanding challenges facing the ABL program is assembling
the subsystems into a fully integrated and operating system aboard an aircraft. With
the Airborne Laser Laboratory (ALL) program in the 1970s and 1980s, the Air Force
has had experience assembling a several hundred watt laser and optics system aboard
an aircraft. Nevertheless, the ABL multi-megawatt laser and precision tracking system
breaks new ground in systems integration. Boeing, the prime contractor, will
construct a special system integration laboratory (SIL) at Edwards Air Force Base to
assemble and test the COIL exactly as it is configured in the aircraft. The facility will
have provisions for simulating the behavior of the aircraft and subjecting the COIL to
the shake, rattle, and roll it will experience aboard the 747.
While the COIL is being tested in the SIL, the BC/FC system will be installed in
the aircraft along with the Battle Management, Command, Control, Communications,
Computers, and Intelligence (BMC4I) system and a surrogate laser in place of the
COIL (see Figure 2). The integrated system will be fully tested on the ground and in-
flight with improvements made as required to bring it to full operational capability.
Large ground-based multi-megawatt lasers (i.e. MIRACLE, NOVA, and NIF
(the latter two at the Lawrence Livermore National Laboratory)) all require
extremely rigid and stable mounting systems because any small misalignment could
cause a catastrophic failure of one or more optical components. Further, high power
lasers must be contained in exceptionally clean, stable environments to prevent the
destruction of optical components, such as mirrors. The ABL requires that the three
laser beams (tracking, beacon, and COIL) be co-aligned to within a few micro meters.
No aircraft can provide that level of rigidity and stability needed to maintain the
integrity of the ABL, so the plan for the ABL is active alignment. That is, several
auxiliary lasers will constantly monitor and reposition key optical components to
maintain alignment. The Air Force believes that this system can in real time adjust to
the flexing of the aircraft as it flies.
In addition to protecting the optical components, the active alignment system
is to assure the precision needed to direct the laser beams at the target missile. The
concepts of the active alignment system have been studied and demonstrated in the
Lockheed Martin (LM) laboratory brass-board mock-up of the ABL optical system.

LM has demonstrated, under simulated flight conditions, that the active alignment
system can maintain the alignment of the BC/FC systems in flight.
Software Development
The computer system and attendant electronics will use commercial equipment,
packaged in commercial assemblies. The software is designed and developed in
modules and tested in the Boeing Open System Architecture (BOSA) for
communications and operating systems.
The software architecture consists of five major components: 1) BMC4I
software for the conventional missile detection and IR tracking, and the overall
communication and coordination package; 2) Laser control software; 3) BC/FC
control software for the optical systems for tracking and adoptive optics; 4) GS,
ground support software; and 5) and operational software. This represents a
substantial package of first generation integrated software modules that could pose
some risk to the overall PDRR schedule.
In October of 1999, the ABL software team successfully demonstrated the the
integrated battle management hardware and software systems. This system is designed
to ensure that the ABL can accurately detect and identify a ballistic missile and pass
that information on to the bean system or another platform if the ABL is out of
range. This is the last test in for the “Build-1A,” the basic software architecture for
ABL’s battle management system that controls the six infrared missile search and
track sensors.
Field Operations and Life Cycle Costs
The complexity of the ABL would demand considerable field support for its
operation. Fuel for the COIL, spare electronics, and spare optical components are
required. In addition, to support two ABL aircraft on station 24 hours per day
requires a total fleet of seven aircraft with at least four and possibly five aircraft
stationed in the theater of operation. The current Air Force estimate for ABL support
and operating personnel totals 300. At this time CRS has not seen a cost estimate for
the operations.
The Air Force has estimated the costs for engineering, manufacturing and
development (EMD) at $1.1 billion and $3.6 billion for the production of seven
operational aircraft by the end of 2009. The Air Force estimates $4.4 billion for the
20 year operational cycle for the ABL aircraft. Although single components and
commercial components have been shown to exceed derived requirements for the
EMD, no subsystem assembly has undergone life-cycle testing in an ABL simulated
environment. Consequently, the failure rate and maintenance requirements for
components and subsystems in the ABL environment can only be inferred from
experience with other systems. In sum, the EMD, production, and life cycle costs,
totaling $9.1 billion, are necessarily somewhat uncertain, with true costs
undetermined at this time.

Congressional Concerns and Issues
Current Technical Issues
The legacy of the Airborne Laser Laboratory and technology maturation over
the past decade have led the Air Force to believe that a multiple, parallel path program
(developing and testing key ABL components simultaneously, often referred to as
concurrency) is the shortest route to a successful ABL. Therefore, the Air Force has
embarked on a program of acquiring long lead items such as the components for the
nose turret and the 747 while completing the technology development and fabrication
of the COIL and the Beam Control/Fire Control (BC/FC) subsystems. This approach
could lead to rapid progress and perhaps lower systems costs, but it has its obvious
risks.
The COIL
As previously indicated, the extent to which the COIL laser can engage and
successfully destroy an enemy missile in the boost phase is critical to the ultimate
success of ABL. According to the AF, past R&D efforts and recent test results
suggest that the COIL, as currently designed is capable of destroying missiles at
operationally required distances during the boost phase. However, others suggest that
significant testing and redesign of the COIL laser will likely be required before the
program moves into EMD, primarily because of the immaturity of the technology²¹
and the unique environment in which the laser must operate (in an airplane that is
constantly flexing and vibrating). If these concerns materialize, the ABL program
could experience significant delays that might become very costly if they result in
suspension or modification of the long lead procurement items such as the second
unmodified 747, the turret window, and the 1.5 meter pointing mirror.
Air Force representatives characterize the COIL as mature technology. While
the AF claims that a flight weighted COIL laser module has successfully completed
initial testing, reaching 110% of required power and acceptable beam quality, others,
including GAO, have questioned the validity of this claim, because the AF has not
simultaneously measured the COIL test model beam for power and quality. Again,
it is important to note that the COIL must simultaneously produce a beam of sufficient
power and quality in order to destroy a missile, at a variety of distances, in limited
periods of time. If the COIL laser does not work as planned the AF will not have a
usable weapon system. Consequently, Congress could request that the AF conduct
a “hot test” (in late 1999 or early 2000, when additional COIL ground tests are
already scheduled to occur) of the flight weighted COIL laser in order to assure that
the laser can meet both power and beam quality parameters necessary to engage
TBMs successfully.
The Air Force argues that the challenges confronting the successful development
and deployment of the laser are engineering in nature and can be dealt with over the

United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept²¹
of Operations, SAB-98-04, February 1998, p. 11.

next 18 months according to the schedule. The Air Force is scheduled to test an
updated flight model COIL until early in FY2000, and is scheduled to demonstrate its
air-worthiness in the third quarter of 2001 (see Figure 4). The first hot fire test of the
PDRR COIL laser is scheduled to occur until July of 2002, prior to the 2003 missile
destruction test.
In June of 1999, the Air Force ran additional tests of the COIL laser. During
these tests, the Air Force reported that the flight weighted laser (FLM) module
achieved 107% of required power. Further the laser operated at high power for more
than 15 seconds, longer than most anticipated operational laser shots.
In late August of 1999, a 300 gallon tank containing concentrated hydrogen
Peroxide (HP) blew up at the TRW COIL testing facility. The FLM was not damaged
in the explosion. The HP in the tank was used to cool the testing equipment in the
laser, not as a fuel for the flight weighted laser. After the equipment was cooled with
HP, basic hydrogen peroxide (BHP) was injected into the laser as fuel for testing the
COIL. This procedure was repeated every time the COIL laser was tested.
The Air Force contends that after repeated use of HP, inadequate cleaning of the
flow tubes may have allowed the HP to contaminate the BHP, which is used to power
the COIL laser. Air Force officials note that this would not occur in the actual ABL
system because BH would be run through the laser before the aircraft takes off and
not reused. However, Victor George, a scientist with over 30 years of experience in
designing and building lasers noted that if the contamination came from the main
laser’s mixture of BHP and not from not from a contaminate due to the reuse of BH,
such an occurrence would be troubling. The Air Force argues that there is no proof²²
that the BHP was the source on the contamination.
Beam Control / Fire Control
As described earlier, the BC/FC includes the missile precision tracking (both
internal to the 747 and external) subsystems, and the AOS beam compensation
subsystem.
A major technical issue is the successful development of the AOS. The ultimate
success of the AOS is dependent on the extent to which the Air Force computer
models accurately characterize atmospheric turbulence in order to “correct” beam
distortion. The purpose of the AOS is to modulate the shape of the laser beam in
order to compensate for the distortions introduced by the atmosphere and thus keep
maximum beam power focused on the target.
Based on its atmospheric turbulence experiments (e.g. ABLEX (1993), ABLE-
ACE (1995), Firepond (1997)), and other experiments, the Air Force contends that²³
it has collected sufficient atmospheric turbulence data to develop accurate computer

Explosion Raises Questions Over Airborne Laser, New Technology Week. Oct. 12, 1999.²²
P. 12
A succession of experiments the Air Force carried out to test and validate the concept of²³
adoptive optics for ABL applications.

simulated models of atmospheric turbulence. The program director of ABL contends
that there is a strong correlation between their computer generated turbulence models
and the actual atmospheric turbulence data the Air Force has been collecting for the
past five years. The Air Force is confident that its atmospheric compensation models
will permit the COIL to shoot down a missile at various distances in a variety of
atmospheric conditions. The Air Force has programs in place to continue the G21
collection of atmospheric data and update its algorithms, and for studying advanced
concepts in beam compensation.
Others, including the IAT, have argued that the Air Force has not collected
sufficient atmospheric turbulence data to operate the ABL in a variety of potential
conflict scenarios. While recognizing that the ABL might be effective against targets
at nominal ranges in ideal weather conditions, the Air Force Scientific Advisory Board
(SAB) suggested that “ the ambitious character of the compensation design, together
with the incompleteness of the turbulence data... gives rise to legitimate uncertainty
and even skepticism about the ultimate feasibility of delivering adequate irradiation
on target.” The SAB suggested that the Air Force collect more atmospheric data in
order to document what is “known and unknown about turbulence and the
assumptions made in modeling the weapon performance.” The IAT strongly²⁴
endorsed the need to collect more atmospheric turbulence data.
As previously indicated, AOS is relatively new technology although it has been
widely implemented in modern astronomy. The Air Force has successfully utilized
such technology for a variety of astronomical purposes at its Starfire Optical Range.
The Air Force contends that its success in aiming a laser at a target in space and
utilizing computer controlled deformable mirror to compensate for atmospheric
distortion demonstrates that AOS will be successfully deployed in the ABL.
However, astronomers have pointed out that the AOS system employed for the
ABL is far more complicated than those used in astronomy. They note that
astronomers are pointing a single laser vertically through a turbulent thin vertical layer
of atmosphere, typically 15 km-60 km, as compared to hundreds of kilometers of
atmosphere the three ABL lasers would have to propagate through. Further, while
astronomers have their lasers and AOS mounted on top of a concrete slab, the ABL
AOS must make rapid, critical beam adjustments while operating in a moving airplane
that will be subjected to significant turbulence and vibration as it travels through the
atmosphere.
The Air Force has conducted a number of experiments to determine how
atmospheric turbulence distorts the COIL laser beam, and the extent to which the
AOS can “correct” the distortion. In one such experiment, Firepond, MIT’s Lincoln
Laboratory demonstrated that at a short range (5.4 km), utilizing computer controlled
tracking test on a static target, the beam compensation improved by a factor of four
utilizing an AOS. According to the Air Force, the experiment was designed to
simulate ABL flight conditions for ranges over most of the system’s projected battle
space.

United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept²⁴
of Operations, SAB-98-04, February 1998, p. 10.

Nevertheless, Congress, DOD in response to the IAT report, and the Air Force's
SAB have expressed concern about the adequacy of such tests, given the experimental
nature of AOS technology. In its FY1999 defense appropriations Act, Congress
instructed the Air Force to accelerate testing of its AOS. The SAB noted that beam
control and turbulence compensation testing should “document and describe the
technical features of the design and the uncertainties that need to be tested...tests that
will demonstrate or resolve the issues and the schedule for the testing.” In response²⁵
to these concerns the Air Force has scheduled a series of tracking and beam
compensation tests from North Oscura Peak (NOP) in New Mexico. Using both fixed
and moving targets, out to a range of 50 km, the Air Force will conduct
comprehensive tests on tracking and beam compensation. Electronic scoring will be
conducted against airborne target boards mounted to an aircraft flying at scaled
ranges and velocities to represent ABL attack scenarios. These tests will utilize a
surrogate tracking laser and AOS (positioned on the ground), to validate the
operation of the ABL BC/FC system. Additional tests, utilizing the same surrogate
subsystems, will be conducted against missile targets in FY2000.
Another issue which has not been raised extensively is the tracking accuracy of
the ABL beams. In order to keep the beam focused on the missile, the ABL system
must maintain a very precise (on the order of a few microns) alignment of the optical

United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept²⁵
of Operations, SAB-98-04, February 1998, p. 11.

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components mounted in the aircraft. The technique for maintaining this precision is
to have an internal alignment laser and optical components to make rapid, precise
adjustments to the three laser beams to keep them co-aligned. The design has been
tested in the laboratory, but the “reality” testing will occur when the BC/FC system
is mounted in the aircraft which is scheduled for the third quarter of FY2002. The
stability of this alignment system is crucial to the success of the ABL.
ABL Testing
As described at the start of this section, the Air Force has embarked upon a dual
path program of engineering and fabrication of key technologies, and the acquisition
of long lead components. The 747 has a 24 month delivery time and the turret
window has a lead time of 36 months. These lead times have implications for the
EMD phase of this program. The testing regimen for the PDRR derives from this
context (see Figure 4).
Congress has expressed concerns about the adequacy and timing of the ABL
testing program. In its FY1999 defense authorization report, the Senate Armed
Services Committee (SASC) noted that much of “the testing necessary to make well
informed judgements about the technical viability of the ABL program will not begin
to occur until fiscal year 2002, just prior to the program entering EMD.” (In²⁶
actuality, long lead purchases and design work for the EMD phase commences in the
fourth quarter of 2002, the year before the final testing of the PDRR program). The
Committee also noted that the first time the Air Force plans to collect optical data on
the performance of a laser fired horizontally through the atmosphere is during the last
quarter of fiscal year 2002, during its first attempt to shoot down a missile just prior
to milestone II review. Some Air Force officials have expressed concerns about the²⁷
testing protocols because many of the tests, prior to FY2002, do not involve the
actual hardware that will be flown on the ABL. They have noted that integration
testing of the AOS and the COIL is not scheduled to occur until September of
FY2002.
Air Force documents state that its PDRR testing program is designed to
demonstrate that key ABL technologies are mature and ready for an ABL weapon
system. The scope of the testing is gradually increased, going from proving
components, to integrating components, to proving subsystem, to full systems testing.
The Air Force says that these subsystems had been demonstrated previously to
adequate levels of proficiency either individually or in another application and that
earlier Airborne Laser Laboratory success has provided a valuable legacy of working
with airborne lasers.
While the PDRR testing plans characterize certain key subsystems of ABL as
mature technology ready for the insertion into the ABL, others disagree. The Air
Force Scientific Advisory Board (SAB) characterized ABL key technology (AOS and

Senate Armed Services Committee, National Defense Authorization Act for Fiscal Year²⁶^th^nd

1999, 105 Cong., 2 sess., 1998, S. Rpt. 105-189. P. 136.

Ibid., P. 137²⁷

the COIL) as “experimental systems.” Others have pointed out that “mature”²⁸
technology means a capability that has proven itself numerous times under a variety
of circumstances.
The IAT stated that “given the large investment in the initial flight test system,
the stated PDRR objective of demonstrating a representative TBM target kill appears
too limited.” Given the size of the PDRR investment, the IAT suggested the ABL
PDRR should expand its testing protocols in order to gather additional data and²⁹
expand the test envelope for both the aircraft and targets. DOD’s response to the
IAT noted that while additional testing will increase near-term costs and delay ABL’s
initial operational capability (from 2008 to 2009), the added tests will ensure that the
expenditures required for the ABL’s EMD phase are justified.³⁰
While the expanded ABL testing program may help the Air Force gain valuable
knowledge about critical subsystems, in most instances the tests will not utilize the
actual hardware that will fly on the PDRR ABL. In order to address congressional
concerns, as well as other program critics, the Air Force could utilize as much actual
PDRR hardware as possible in its future testing. For example, this could include
within practical feasibility, demonstrating AOS capabilities during North Oscura Peak
testing scheduled to begin in 1999 and continue into 2000.
ABL PDRR Schedule
Another issue closely aligned with testing is the challenge of integrating all of the
major ABL subsystems. The Air Force has recently revised its integration schedule,
strengthening the ABL test protocols by adding additional PDRR tests focusing on
beam control, atmospheric compensation utilizing AOS risk reduction in beam
control, and atmospheric characterization. (see Figure 5).
Despite these additions, overall systems integration remains a formidable
challenge. While the Air Force has delayed initiating systems integration activities by
a year, the time period for completing systems integration activities remains essentially
the same. Aircraft integration will begin the fourth quarter of FY2001 with the
BMC4I system. At this time the BC/FC will be installed in the aircraft along with³¹
a surrogate for the COIL. This almost complete ABL system will be flight tested and
made ready for the COIL by the third quarter of FY2002. Beginning in the fourth
quarter of FY2001 the Air Force plans to assemble the COIL in the systems
integration laboratory ( SIL). The COIL will be assembled and subjected to in-flight
conditions in the SIL while the BC/FC is undergoing its flight tests. Then the COIL
will move on to the aircraft in the first quarter of FY2003. This will be the first time
all of the major subsystems of the ABL will be tested as an integrated weapon system.

United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept²⁸
of Operations, SAB-98-04, February 1998. P. 10.
Op Cit. IAT, p. 5.²⁹
DOD’s response to the IAT report. P. 6.³⁰
BM/Battle Management, CI/Command, Control, Communications, Computers and³¹⁴
Intelligence

This allows about six months before the ABL is scheduled to shoot down a missile
during flight tests.
This would appear to be a very aggressive schedule for both the key technologies
and the system integration and testing prior to the flight tests. The SAB report, of
February 1998 on the ABL, expressed reservations about the PDRR schedule.
The program evolution as currently planned is rational in its sequencing of tests,
but the schedule appears to be unrealistically brief in the flight test phase. Past
experience with high power laser systems and large beam directors suggests that
new and difficult problems will surface in that phase, and many flights and targets
will be needed to sort them out. It would be advisable for the SPO to develop
contingency plans to prepare for the possibility that the current success-oriented
schedule is not achieved.³²
This would also be the first time that the system’s operational software would
be tested. The SAB study is about one year old and although the program has made
significant progress since its release, the integration phase is often the most critical in
any project. Any significant delays caused by underperformance in the project will
likely increase its overall cost.
Regarding the EMD, the Air Force has scheduled procurement of the long lead
components and design efforts to commence in the fourth quarter of FY 2002. This
includes the purchase of the second unmodified 747 aircraft. Under this schedule, the
Air Force would be committed to buying a second modified 747 one year before the
flight test and evaluation phase for the PDRR is completed, including the actual
shooting down of a missile in late FY2003. Moreover, the aircraft will not be modified
until one year after PDRR demonstrations are complete. This could be an issue for
Congress and the independent review team to consider. A second window was
purchased under the PDRR program as a risk reduction backup for an item with a 36
month lead time. Unless the PDRR program should need the second window, it will
be used for the EMD phase of the project.
Counter Measures
An issue that appears to be receiving greater attention in Air Force ABL
documents is a discussion on counter measures that an adversary may employ to
reduce or defeat the intent of the ABL. While much of this discussion would
necessarily occur in a classified environment, the Air Force SAB has recommended
that the Air Force improve its response to both current and long term counter
measures. Others have suggested that since the ABL is not scheduled to be
operational until 2009, it seems reasonable to expect that the Air Force should
examine the potential evolution of both technical and tactical counter measures.

United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept³²
of Operations, SAB-98-04, February 1998, p. 10.

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In the near term, the Air Force might want to examine the prospects of an
adversary applying a very high polish on the outer casing of the missile, in an attempt
to make tracking and targeting more difficult. In the long term, the SAB and others
have argued that potential adversaries could harden existing or new TBM against
attack. They could also build a new missile that has a shorter boosting time, thus
reducing potential ABL engagement times, or employ early release of sub-munition
payloads. However, it is important to note that the ABL design may make it a more
effective weapon against missiles carrying submunitions than other TAMD systems.
Another counter measure would be to spin the missile when it is launched which³³
then could take longer to destroy because of laser heat dispersion. In terms of
tactical counter measures the enemy could launch missiles from ranges beyond ABL's
striking ability, or quickly move a missile and attack before the ABL is deployed. In
most instances a potential adversary would be likely to employ a mixture of technical
and tactical counter measures which could seriously compromise the operational
capability of the ABL. The IAT recommended that the AF undertake an aggressive
test and analysis program to “gain a thorough understanding of the effectiveness of
such counter measures. This information will be needed to support an informed³⁴
Milestone II decision at the conclusion of PDRR. “
In September of 1998, the Air Force announced that it is forming an independent
Directed Energy Countermeasures Assessment Team (DECAT) to examine potential
technical and tactical counter measurers that might be employed by an adversary to
defeat the ABL. The director of this team will report to Air Force Headquarters, not
to the Director of the ABL program office. Nevertheless, key congressional
committees may want to participate in closed briefings with the Air Force, and other
independent experts, to examine the potential short and long term operational
consequences of various technical and tactical counter measures likely to be employed
against the ABL. The Air Force and/or Congress could request the LCAT to develop
potential counter measure tactics that could be deployed and tested during the latter
stages of PDRR testing.
The recent acknowledgment that the Russians are developing a new surface to
air missile (SAM) with a range of 250 miles raises serious operational counter
measure concerns for the ABL. The 250 mile range is 10 times the range of SAMs
used in Kosovo that made it difficult for U.S. military commanders to successfully
prosecute the air campaign. Referred to as the S-400, the 250 mile SAM is not
scheduled to be operational until 2005. According to individuals inside and outside
of the Pentagon, the new SAMs’ extended range will require important platforms such
as the ABL to “stand off”much further than originally planed when shooting at³⁵

missiles.
United States Air Force Scientific Advisory Board, Airborne Laser Scenarios & Concept³³
of Operations, SAB-98-04, February 1998, p. 7.
Op. Cit. IAT Report. p.7.³⁴
John Donnelly, Defense Week, Sept. 27,1999. Coming SAMs have 10 Times Grater Range³⁵
Than Today’s, Vol. 20, Number 38. P. 14.

However, Air Force officials note that the Service has not lost any high-value
assets such as the Boeing E-3 Airborne Warning and Control System (AWACS) or
the Northrop-Grumman E-8 Joint Surveillance Target Attack Radar System (Joint
STARS) to a SAM or fighters since such systems became operational. The Air Force
contends that it is capable of protecting the ABL from similar threats that have
confronted AWACS and Joint STARS. Nevertheless, these systems have not had to
confront SAMs with greater ranges, speed and the ability to engage 6 separate
targets.
FY1999 Authorization and Appropriations
Congressional questions have been raised about the ABL program from its
inception. In FY1994 Congress raised concerns about the Air Force’s request of
$3.845 million for airborne laser technology development. The FY1994 Senate
appropriations report denied the request stating that “a recently released study on
Boost Phase Intercept (BPI) determined that ABL was one of the riskiest approaches
to attacking ballistic missiles immediately after launch.” The report also noted the
$773 million cost to develop an ABL demonstrator through FY2001 was not
affordable. Congress appropriated $1.945 million for ABL technology in Fy1994,
with the stipulation that the Secretary of the Air Force provide a rationale for
pursuing this technology and documentation that the program is fully funded in the³⁶
Future Years Defense Program.
Essentially, past congressional concerns have centered around two main issues
that were raised in the Senate’s FY 1997 Defense Authorization report. The first is
that the Air Force had not adequately demonstrated (through testing) that the key
technologies were ready to be assembled into an ABL. And second, that the ABL
concept of operations would not allow “the system to be cost and operationally
effective.” In regard to the second issue the Committee wrote that in terms of
operations “ the ABL will be forced to stand off approximately 90 kilometers from
the forward edge of the battle area... but the ABL will have a range well below 500
kilometers...in most cases below 300 kilometers. This means that the ABL will have
very little capability against short-range (300 km) missiles and longer-range missiles³⁷
launched from significant distances behind the forward edge of the battle area.”
In its FY1999 defense authorization report, the Committee again raised these
two issues, noting that “the Air Force had not adequately demonstrated the feasibility
of the necessary technology to begin such significant investments.” The report stated
that the testing necessary to make important decisions about the technological
viability of the ABL program will not occur until FY2002, just prior to ABL entering
EMD. [In fact PDRR flight testing is one year following budget commitments to

Conference Committee, Making Appropriations for the Department of Defense for the³⁶^rd^st
Fiscal Year Ending September 30,1994, and Other Purposes. 103 Congress 1 sess., 1993
H. Rpt. 103-339. P. 134.
Senate Armed Services Committee, National Defense Authorization Act for Fiscal Year³⁷^th^2nd

1997, 104 Cong., sess. 1996, S. Rpt. 104-267. P. 180.

EMD (see figures 4 & 5).] The Committee again questioned the cost and operational
viability of the program. ³⁸
The authorization conference report instructed the Secretary of Defense to form
an independent assessment team (IAT) of experts from outside of the DOD to review
the technical and operational aspects of the ABL program. By March 15, 1999, the
IAT was to assess the following:
1) Whether additional ground testing or other forms of data collection
should be completed before initial modification of the commercial
aircraft to the ABL configuration;
2) The adequacy of exit criteria for the program definition and risk
reduction phase of the ABL; and

3) The adequacy of current ABL operational concepts.³⁹

The report also reduced the $292.2 million request by $57 million,
recommending $235.2 million, and limiting FY1999 spending to $185 million until 30
days after the Secretary of Defense submits the IAT report to Congress. The IAT
report was submitted to Congress on March 9, 1999.
Senate appropriators have also called for additional testing of the COIL laser
prior to proceeding to system integration activities in FY2001. In its FY1999
appropriations report, the Committee stated that the Air Force has failed to
demonstrate propagation and lethality of the COIL. The FY1999 Appropriations
Conference Report directs the Air Force to "conduct a meaningful ground
demonstration of the capability to produce a high energy beam, compensate the beam
for atmospheric disturbances, and measure the deposition of laser energy on a target
under realistic test conditions. " The Conferees reduced the budget request by $25⁴⁰
million to $267.2 million to reduce concurrency in the program and to incorporate
lessons learned from the tests back into the ABL program.
The Air Force contends that its testing program has been carefully structured to
ensure that the critical risk areas associated with the various ABL subsytems have
been properly characterized through a prudent testing and evaluation process. The Air
Force states that the ABL subsystem test plan will address all the issues raised by
Congress prior to the start of systems integration activities in 2002. For example, in
response to the appropriators’ call for additional testing of the lasers and AOS, the
Air Force will accelerate its planned time table for the NOP tests on a mock-up of the
BC/FC subsystem and a surrogate high power laser from early in 2000, to the
beginning of 1999. The COIL laser will undergo a long series of tests at each stage

Senate Armed Services Committee, National Defense Authorization Act for Fiscal Year³⁸^th^nd

1999, 105 Cong., 2 sess., 1998, S. Rpt. 105-189. P. 136.

Conference Committee, The Strom Thurmond National Defense Authorization Act for³⁹^th^nd
Fiscal Year FY1999, 105 Cong., 2 sess., 1998, H. Rept. 105-736, P. 32 and 33.
House Committee on Appropriations, Making Appropriations for the Department of⁴⁰
Defense for the Fiscal Year Ending September 30, 1999, and for Other Purposes.105th^nd
Cong., 2 sess. 1998, H. Rpt. 105-746. P. 148.

of development culminating in a full, six module subsystem in the SIL by midyear of

2002.

In response to Congress, and the findings of the IAT, the Air Force has
expanded ABL’s testing and risk reduction activities, adding more flight tests, and
more attempts at shooting down TBM representative targets under a variety of
operational circumstances (not just a single “representative target”) before
recommending moving ABL to EMD in FY2004.According to the Air Force, the
$25 million reduction and the call for more testing has led to a 12 month delay in
some elements of the program, and an estimated cost increase of $300 million for the
PDRR.
FY2000 Authorization and Appropriations
As part of the FY2000 defense authorization bill (P.L. 106-65) Congress took
additional steps to reduce concurrency (developing and testing key ABL components
simultaneously, versus developing and testing key components one-at-a-time or
sequentially) in the ABL program. The Senate Armed Services Committee report (S.
Rpt. 106-50) noted that the Secretary of Defense must develop an acquisition strategy
for the ABL that strikes an appropriate balance in managing risk and concurrency.
The legislation instructs the Secretary of the Air Force not to begin modification of
the PDRR aircraft (which Boeing delivered in January of 2000) until the Secretary of
Defense certifies to Congress that test and analysis results based on the following
activities:

1. The North Oscura Peak dynamic test program;

2. Scintillometry data collection and analysis;

3. The contermeasures test and analysis effort;

4. The letality/vulnerability program; and⁴¹

5. Reduction and analysis of other existing data.

Congress wants to be sure that all the ABL major subsystems meet minimal
operational requirements before the PDRR plane is modified. Any modification could
prevent the Air Force from returning the plane to Boeing if a major technical obstacle
arose during PDRR testing.
Congress also instructed the Air Force not to modify the second aircraft (The
EMD plane with a scheduled delivery date of 2003.) until the PDRR plane
“successfully completes a robust series of flight test that validates the technical
maturity of the ABL program and provides sufficient information regarding the
performance of the system across the full range of its validated operational⁴²
requirements.” Modification of the EMD aircraft was scheduled to begin prior to the
completion of PDRR testing, including the actual destruction of a theater ballistic
missile in 2003.

Senate Armed Services Committee, National Defense Authorization Act for Fiscal Year⁴¹^th

2000, 106 Cong., 1st sess., 1999, S. Rpt. 106-50. P. 149.

Op. Cit. S. Rpt. 106-50. P. 150.⁴²

Conclusion
The current PDRR testing schedule is likely to present Congress with a series of
difficult decisions. First, as previously discussed, given the uncertainties surrounding
the COIL, Congress may wish to request that the AF “hot fire” the PDRR laser in
order to simultaneously measure beam power and quality, rather than waiting until
FY2002 when the PDRR laser is scheduled to be “hot tested” in the SIL, and on the
airplane in FY2003.
Second, under the current schedule, the Air Force is to purchase a second
modified 747 one year before PDRR flight tests of all the major subsystems are
completed. Given concerns expressed about the maturity of crucial ABL technologies,
Congress may consider delaying the purchase of a second aircraft until after PDRR
testing is completed. Nevertheless, postponing the purchase of long lead items would
predictably lead to additional cost increases and delays in deploying the ABL. It is
important to note that modification of the 747 begins a year after the Air Force places
its order for the plane. This raises the possibility that if the Air Force were to order
the plane as scheduled, Boeing could take the plane back for commercial sale if ABL
is delayed indefinitely, (prior to the actual modification of the plane) at no or minimal
cost to the government.
A third major issue Congress may face centers around the future of the ABL
program and laser weapons in general. As indicated in this report, there is some
concern that the ABL may not be capable of demonstrating that it can meet the Air
Force’s operational requirements as it moves to engineering, manufacturing and
development (EMD). Given that the Air Force will have spent over $1 billion on the
ABL before entering EMD, Congress could decide to extend the PDRR testing
schedule until the ABL demonstrates that the system will be capable of meeting its
operational requirements. Or, if the ABL encountered considerable science and
technology challenges during PDRR testing, Congress could consider using the ABL
as a research and development (R&D) platform that may eventually lead to the
establishment of a different or reconstituted ABL acquisition program.
Fourth, given the desire in and outside Congress to develop laser weapons,
Congress may want to pursue the R&D option even if the Army’s and Navy’s upper
and lower tier TAMD are likely to be operationally ready prior to the deployment of
the ABL. Unlike other TAMD systems, if ABL works as advertised, it may be better
designed for destroying missiles carrying submunitions, before the submunitions are
deployed.
Fifth, if ABL PDRR testing reveals a number of significant scientific and
technical challenges, Congress could decide to cancel the ABL program. If this
occured, Congress could then instruct the three Services and the Defense Advanced
Research Projects Agency to initiate a number of research and development activities
that would eventually lead to a variety of laser based weapons.
Finally, Congress could decide that the current reconfigured ABL program
reduces risks to sufficient levels that would allow the program to proceed to its
expanded PDRR flight tests schedule in FY2003. With additional testing, the

collection of additional atmospheric data and the validation of the AOS compensation
capabilities, Congress and the Air Force could decide that the only practical way of
determining if the ABL will work as designed is to flight test the PDRR plane against
a variety of targets.