Pentagon Accelerates Fielding of High-Power Laser Weapons to Counter Drone and Missile Threats
For decades, military laser weapons promised revolutionary capability but rarely moved beyond laboratory testing and field demonstrations. That is beginning to change. The Pentagon's decision to award nLIGHT Defense and Lockheed Martin Aculight agreements worth an initial $86 million, with a combined program ceiling of $847 million, reflects an effort to turn high-energy laser prototypes into deployable weapons against drones and cruise missiles. The immediate goal is to field containerized systems beginning at about 150 kilowatts of power, then scale them into the 300- to 500-kilowatt range needed to tackle harder and faster targets. The sudden interest in laser weapons has less to do with realizing a science fiction dream than with the brutal economics of modern air defense. Militaries increasingly face inexpensive drones that can overwhelm defenses through sheer numbers. Shooting down a relatively cheap unmanned aircraft with a missile costing hundreds of thousands or millions of dollars may work tactically, but it becomes difficult to sustain during a prolonged attack. A laser changes that equation. Once the military has paid for the weapon, its power supply and cooling system, each engagement mainly consumes electricity. That gives laser weapons what defense officials call a "deep magazine": they can continue firing as long as the system can generate enough power and shed enough heat. Traditional air-defense systems cannot do that. Every missile launch removes one expensive interceptor from a finite supply that must be manufactured, transported, stored and reloaded. The comparison is not quite as simple as "a few dollars of electricity versus a multimillion-dollar missile." Laser systems remain expensive and require substantial support equipment. Still, their marginal cost per shot could make them valuable against the high-volume drone and missile attacks now shaping military planning. What does 150 kilowatts actually mean? Laser power ratings can sound abstract, but they are reasonably straightforward. A 150-kilowatt-class weapon is powerful enough to engage unmanned aircraft and other relatively vulnerable aerial targets when the system can maintain a focused beam on them. The next step, between 300 and 500 kilowatts, would give the weapon more energy to damage tougher targets in less time. The Pentagon sees that class as more suitable for cruise missile defense. Power alone does not determine whether a laser will actually work, however. The system must detect the target, track it precisely and hold the beam on one vulnerable point long enough to cause structural damage, ignite fuel, disable controls or destroy a critical component. The farther away the target is, the harder it is to shoot down. The beam must also remain tightly focused as it travels through the atmosphere. Air turbulence can distort it, while clouds, fog, smoke, dust and heavy moisture can absorb or scatter its energy. That means lasers will not replace missiles. They will add another layer to air defenses, giving commanders a cheaper option when conditions and target geometry allow it while preserving missiles for threats that lasers cannot reliably engage. The race for more power The Pentagon is not stopping at 500 kilowatts. Under the High Energy Laser Scaling Initiative, or HELSI, nLIGHT is working toward a one-megawatt-class laser. The company demonstrated a 300-kilowatt-class system during an earlier phase and later received additional contract options that increased its Phase 2 award from $86 million to $171 million. The three-year effort aims to produce a one-megawatt-class prototype. How powerful is a megawatt laser? One megawatt equals one million watts. Concentrating that energy into a controlled beam creates the potential to attack much more demanding targets. A quick physics refresher helps put that number in perspective. A watt measures how quickly energy is delivered, and one watt equals one joule per second. A joule, as many elementary physics students will know, is roughly the energy required to lift a medium-sized apple one meter off the ground. A one-megawatt laser delivers about one million joules every second, concentrated into a beam. If engineers can keep that beam tight and hold it on the target, surfaces heat, coatings burn, metals soften and structures fail quickly. At that power level, the question is no longer whether the laser is powerful. It is whether engineers can aim it, hold it in place and keep the weapon from cooking itself. A one-megawatt weapon is not simply a 300-kilowatt laser with the power turned up. Higher power creates more heat, places greater demands on electrical generation and makes beam quality increasingly difficult to maintain. Engineers must package the laser, optics, tracking equipment, power supply and cooling hardware into something military forces can move and operate outside a laboratory. nLIGHT uses an approach called coherent beam combining. Rather than building one enormous laser, the system combines multiple laser sources so they behave like a more powerful single beam. The company says it is trying to preserve beam quality while shrinking the full weapon into a transportable package. Its directed-energy systems are intended to support layered land and naval defenses against drones, rockets, artillery, mortars and missiles. nLIGHT wants to fit a ruggedized system into a standard shipping container while leaving room for precision long-range tracking and adaptive optics. That engineering challenge has defeated earlier laser programs. The US military has pursued directed-energy weapons for decades, including the Boeing YAL-1 Airborne Laser, a modified 747-400F fitted with a chemical laser intended to destroy ballistic missiles during their boost phase. The aircraft demonstrated the concept but proved too costly and operationally cumbersome to become a practical weapon. I attended a Boeing briefing in California on the YAL-1 program in early 2010. A general in an olive-drab uniform, his chest covered with brightly colored service ribbons, described the concept to a roomful of reporters. Smiling, he offered a gruesome illustration of what this kind of weapon could do. A laser aboard a US military aircraft, he said, could "melt the head off Saddam Hussein from three miles away." Saddam Hussein had already been dead for years, but the comment painted a vivid picture. I raised my hand and asked whether he worried that US adversaries would eventually acquire the same technology and use it against us. The general's smile faded. He shrugged. "Weapons proliferate," was all he said. Modern solid-state and fiber lasers avoid some of the problems associated with large chemical systems, but they still need enormous amounts of electrical power, precise beam control and effective cooling. The difference now is that weapons and military technology can proliferate at something closer to commercial speed. Cheap drones, loitering munitions and increasingly autonomous systems are spreading rapidly, forcing militaries to find defenses that do not always involve firing another explosive projectile. Jamming, spoofing, blinding sensors and damaging electronics have become part of the defensive mix. So have lasers. An unlikely defense company nLIGHT finds itself in an unusual position. For years, it was a mostly anonymous company building high-power fiber lasers for industrial applications. Think sheet-metal cutting for commercial heating and ventilation systems that eventually end up on the roof of an office building. Very few people would have identified nLIGHT as an emerging defense contractor, much less a potentially important one. The company's founder and longtime CEO, Scott Keeney, began his career as director of manufacturing at Pacific Coast Feather, a bedding company that produces pillows and comforters. That background hardly screams "future player in the military-industrial complex." Then the threats changed, and the Pentagon su