While the other armed services have taken a "wait and see" posture toward lasers as a means of destruction--they have long been used as target designators and as sensor "blinding" devices--the Air Force is pressing ahead on its own, having decided that laser technology is ready to be used in a weapon ideal for theater ballistic missile defense.

The planned system, called the Airborne Laser, is one of the two research and development efforts designated as USAF's top priorities. (The other is the F-22 air superiority fighter.) The service touts it as nothing less than a "revolution in warfare" that portends huge changes in the speed at which future battles will be fought.

"The technical challenges are well understood, ... and we have a wealth of enabling technologies available that have already been invented," Program Director Col. Michael W. Booen said at an Air Force Association briefing for industry at AFA headquarters in Arlington, Va. "It's a pretty aggressive schedule, but we are 'buying down' the risks so that ... there are no big surprises that could seriously upset the schedule."

Booen added that the day of laser weapons "is closer than you might think."

Assuming that the Pentagon and Congress continue to fund the ABL at the requested rates--and so far they have--the first ABL aircraft capable of performing at least limited theater ballistic missile defense missions will be available in late 2002. Under the same conditions, the full planned fleet of seven aircraft is to be operational in 2008. The estimated cost of development and procurement: $6.1 billion.

The payoff is expected to be high. The operational concept calls for ABL aircraft to orbit in airspace over friendly territory, much in the manner of USAF's E-3 Airborne Warning and Control System or E-8 Joint Surveillance and Target Attack Radar System aircraft, and watch for the plumes of a ballistic missile launch. Should a Scud-type enemy missile be fired, the ABL airplane will be able to detect the launch, track the missile, target it with a low-power laser, and then focus a multimegawatt chemical oxygen-iodine laser on its body.

This could be done from "hundreds of miles away," Booen said, noting that the specific range is classified. The generated heat will weaken and rupture the missile skin, causing the entire missile to either explode or tear itself apart while still in the boost phase.

Besides the speed of the missile's destruction, confirmation that it was indeed destroyed would come almost instantaneously, greatly helping in the overall defense equation.

The ABL will use an infrared search and track mechanism. However, it won't be the IRST system being developed for the F-22 fighter but one already used on the Navy's F-14 Tomcat fighter. "We want to minimize the risk in the program," Booen noted. The IRST on the F-14 is a known quantity; that of the F-22, though sure to be more advanced, is still in development.

Likewise, the ABL will be able to take advantage of some 157,000 lines of computer code already written for the AWACS, in another example of using off-the-shelf elements to cut cost and risk.

Under current Air Force plans, the developmental model of the ABL will be able to carry enough chemical fuel for 20 shots at a cost of about $1,000 apiece; the fully operational version will carry a magazine capable of 40 shots. The number of shots and fuel consumed depend on the type of target and distance to it.

The need for a better theater missile defense was demonstrated in the Gulf War in 1991, when a Scud missile fired by Iraq flew toward Dhahran, Saudi Arabia. It was intercepted by an Army Patriot missile, but when the booster fell apart, the warhead fell on an American barracks, killing 28 troops. There are today more than 30 countries with short- to medium-range ballistic missiles, and more are expected to acquire them because such weapons are relatively cheap.

"There will be a tremendous deterrent effect from this system," Booen said of the ABL. Because the airborne laser system will destroy a missile soon after launch, its warhead--be it chemical, biological, conventional, or nuclear--would fall back on the territory of the nation that fired it. Faced with the ABL, an enemy would soon learn that ballistic missile attacks could be highly counterproductive.

Reinforcing the deterrent value is the fact that the ABL will be able to engage multiple targets in quick succession and carry enough chemical laser fuel on board to conceivably shoot down as many as 40 missiles--reducing an enemy's potential for overwhelming it by launching TBMs in multimissile salvos.

In addition, ABL will be joined by the Army's Theater High-Altitude Air Defense system and, if the theater of operations is close enough to an ocean, the Navy's Area- and Theater-Wide missile defense systems, all of which use missiles for terminal defense against incoming missiles.

The ABL by itself would probably not be able to handle mass launches of TBMs, but "we will make the problem significantly easier for the point-defense systems" such as THAAD and Patriot, Booen asserted.

Most of the critical technologies already are in hand. In addition to the IRST, the laser itself is well understood and has already been demonstrated at 120 percent of the necessary power levels. Also available are the "adaptive optics," or deformable mirror, in the system's 1.5­meter telescope. These compensate for atmospheric turbulence and thereby allow the laser beam to remain narrowly focused-a product of Strategic Defense Initiative development from the 1980s. The airplane which will carry it all is an off-the-shelf Boeing 747-400F freighter, with over 30 years' experience behind it and a worldwide maintenance, parts, and support system already in place.

"There's a 25-year legacy of knowledge ... out there of trying to operationalize lasers," Booen noted, referring to the Airborne Laser Laboratory, a converted 707 testbed airframe which, in the late 1970s and early 1980s, demonstrated a limited laser capability against air-to-air missiles and drones.

Among the lessons learned from the laser lab were "system integration ... and beam control." These tasks are different on the ABL, but the older system provided an outline of where the program's toughest challenges may lie, Booen said.

A five-year plan to obtain the first ABL system was chosen not just to expedite the fielding of a capability deemed urgent for troop protection but also because "that's about as far out as people in Washington tend to look, nowadays," Booen said. Financing programs that go beyond the five-year budget cycle have fared poorly in the budget deliberations of recent years.

In addition to its primary mission of shooting down TBMs, the ABL will also have some inherent capability to perform other, "adjunct" missions such as surveillance, protection of other high-value airborne systems, defense against cruise missiles, and suppressing enemy air defenses.

A Boeing-led industrial team that includes TRW and Lockheed Martin was awarded the contract for ABL program definition and risk reduction just over a year ago. The team will first produce a half-power system, which will demonstrate the effectiveness of the ABL against live launches of typical TBMs. If successful, the team will go on to develop and build the more capable system.

Top of the Clouds

The initial airplane-known as the YAL-1A Attack Laser-will have six laser modules on board. The modules "are like batteries," said Booen. "When you put more of them together in series, you get more power." At this stage, fabricating, flying, and testing the first "flight weight" laser modules is the top program challenge and priority. The all-up version will have 14 laser modules.

While the ABL will be able to compensate for different atmospheric conditions, it cannot shoot through clouds. For that reason, the ABL will fly at 40,000 feet, above the clouds, and shoot missiles once they break through the undercast, if any. On cloud-free days, it would be possible to engage earlier.

Booen said that weather balloons and program personnel are collecting atmospheric information in the skies over the Korean peninsula and the Persian Gulf as "representative" areas where the atmosphere has different effects on laser propagation. The two areas are being looked at "because those are the main areas of interest right now, ... areas where we might have to deploy the ABL," he said.

A typical TBM will break out of the clouds some 40 seconds into its flight. The ABL will need about 10 seconds to lock onto the target and will lase it for between 18 seconds and a minute, depending on its distance and trajectory.

Harry E. Schulte, Air Force program executive officer for weapons, said that it won't matter if the target missile is polished to a mirror-like finish; the laser beam, focused to a spot the size of a large frying pan, will still be able to heat up the missile skin sufficiently to cause it to rip apart.

"Armoring the missile is not an effective countermeasure, either," Schulte said, since the additional weight required would make it hard to get the missile off the ground in the first place.

At $1,000 a shot, the ABL system will be considerably more cost-effective on a per-target basis than other missile defense systems which "use a missile to hit a missile," Booen noted. A single ABL shot will be at least 50 times cheaper than a typical air-to-air missile.

The laser will be fired from a rotating turret mounted on the nose of the aircraft. Different versions of the turret are now being examined in a wind tunnel to find the optimum configuration.

Booen observed that the ABL has "inherent deployability" and can fly from the continental US to any overseas contingency within 24 hours, already loaded with its first magazine of laser fuel and carrying an augmented crew. With air-refueling capability, it can remain aloft and shooting as long as the laser fuel holds out, without the need to stage out of a foreign base.

As for replenishment, a single C-17 can lift enough laser fuel to a forward operating base to allow the ABL to engage 140 more targets. The ABL has "an incredibly small airlift footprint," Booen noted, especially when compared to other systems in the ballistic missile defense architecture.

With the ability to look for targets in a full 360-degree arc, the ABL will be able to instantaneously compute not only the launch point but the intended impact point of a TBM and relay this information to the theater commander and the chief of missile defense, so other BMD systems can be cued.

Knowing the launch point would allow attack airplanes to vector immediately to the vicinity to destroy any other missiles being readied for launch at that site, greatly simplifying the kind of vexing targeting problem first seen during the "Scud hunt" in the Gulf War.

In Roving Sands '97, an exercise conducted earlier this year at White Sands, N.M., the ABL was gamed into the scenario. Booen reported that the theater commander in chief "kept the ABL in the air" even after its laser fuel was exhausted because of the rich intelligence and surveillance data it was able to provide.

The exercise proved valuable, Booen said, because officers at 9th Air Force "really didn't know much about the Airborne Laser" and were able to see it in simulated action and learn "how to best employ it." For example, a tactic was developed of "moving the orbit up" closer to "the front lines" as air superiority was achieved and maintained; this allowed greater coverage of the enemy's territory.

The ABL will also be able to cue-and be cued by-planned Space Based Infrared System satellites.

When the Air Force has seven ABL aircraft available around 2008, the typical response to a contingency will be to send five aircraft so that a 24-hour watch can be maintained. Two would likely remain in the US for training, test, or depot purposes and could also serve as a reserve in the event of a second contingency arising elsewhere in the world.

The system will be considered to have reached true Initial Operational Capability with the delivery of three full-up ABL airplanes in 2006.

The program office is insisting that the first test aircraft be deployable and combat-capable "because of the JSTARS lesson," Booen said. Joint STARS was in operational test when the 1991 Gulf War broke out, and two test airplanes were drafted into service for that conflict. The system got its shakedown in real-world conditions and performed beyond expectations. The lessons learned from that deployment, however, led to many revisions and changes; it was not until this year that the "full-up" Joint STARS was declared operational.

The ABL project office has calculated that the seven fully operational laser airplanes will cost $4.9 billion over 20 years to maintain and operate, making for a total program cost of $11 billion.

Booen said constructing the flight weight laser module is the toughest challenge. The program office wants to significantly cut the weight of the airplane because such a weight reduction would allow the aircraft to remain aloft longer without aerial refueling and reduce the fuel penalty for operating at a higher altitude, if such was necessary.

With the current off-the-shelf materials and design available, the demonstrated laser module weighs 5,536 pounds. The planned weight of the flight weight laser module is 3,104 pounds, and the goal is a production module weighing in at just 2,020 pounds. The weight reductions will be accomplished with new materials and a streamlined design.

The ABL program office is also pursuing as many streamlined acquisition procedures as possible, Booen noted. The program office itself is limited to no more than 50 persons-"unprecedented for a program of this magnitude," he noted-and many commercial practices are being used to keep costs down. For example, the Air Force will buy the 747-400F aircraft "just as if we were United Airlines or Federal Express ... and we will pay just like a commercial customer," with a time payment plan and a minimum of red tape.

"We're getting the best price the Air Force has ever gotten" on an airplane of such complexity, Booen asserted. The selling price is around $145 million per "empty" airplane, without the laser system aboard.

Furthermore, the system program office is leaving more of the tasks usually done by the government to the contractors, who warrant the system in exchange for less oversight of the many steps involved in its construction.

Booen noted that, within the Air Force acquisition community, "not everybody is convinced" that commercial practices are the best way to obtain high technology systems, particularly those on which so much is riding. "We have to do some selling of this concept," he said.

However, the system itself is proving highly impressive to regional commanders in chief. Booen said he has taken a "road show" around to regional CINCs to explain the ABL's mission and capabilities. According to Booen, "They wanted us to buy more airplanes. That's a strong show of support."

Booen also noted that he has been asked whether the program could be accelerated, given the tremendous benefits it offers to protecting troops based abroad.

He said, however, that "right now, we're on a reasonable schedule" that is neither too risky nor too expensive. While shifting the program into a higher gear would be possible, the benefit would be measured in gains of only months rather than years. "We couldn't shave two years off the program," given the long lead time of components such as the 1.5-meter telescope, which must be carefully ground in a lengthy and complex process.

By mid-1997, the program was within one percent of its targeted cost and within two percent variance of its planned schedule, Booen noted.

The Airborne Laser, Booen asserted, will "revolutionize warfare ... much in the same way that stealth and radar did." While those programs were developed in complete secrecy, which "can be helpful" in developing a revolutionary weapon, the ABL is being developed "all in the white," or out in the open, avoiding the often significant costs and delays inherent in compartmentalization and ultrasecrecy.