Last week, Lockheed Martin used its Advanced Test High Energy Asset (ATHENA) laser to mangle a Ford F-150. The test once again proved that dollar for dollar, lasers may be the most efficient weapon system known to man for sparking breathless overexcitement and sloppy science fiction references in the media amounting to "Pew! Pew! Pew Pew Pew!"
Weapons break things. They often do this by applying enough energy or force to an object to crush, shatter, explode, or otherwise dramatically exceed a target's physical limits. In the case of conventional weapons — e.g., knives, guns, and bombs — this mainly consists of pressure from a blast or kinetic energy delivered by sharp, jagged, and/or pointy things.
Lasers, like any other weapon, transfer energy to a target. But instead of transferring something concrete like kinetic energy via a bullet, lasers impart thermal energy via light. Battlefield lasers work much the same way that a magnifying glass held over hapless ants on a sidewalk works on a sunny day: They don't usually cause a dramatic explosion — they just melt, heat, or cook the unholy bejeezus out of something. Until it breaks.
Strictly speaking, if you quickly send enough thermal energy into an area, it can melt or vaporize stuff — or even turn it into plasma — and that can result in a kinetic reaction that in turn can blow the stuff up. But today's military lasers have power levels that are nowhere near high enough to do that.
Super slow-motion video of lasers blasting very small things
But never fear, all hope is not lost. While fragments, shrapnel, and projectiles have the advantage of putting a lot of energy on target all at once, lasers have the advantage of being able to continue applying energy. A laser is searing and persistent. It is the burning shame of weaponry.
Pointing a laser at the same spot for a long time won't necessarily cause it to explode, but it will melt a hole in it. As you may have figured out from your own experiments as a juvenile delinquent with a magnifying glass, this is a pretty good way to break something.
Some targets, like tanks, take forever to break with a laser. However, other military targets are far more delicate. For example, some missiles rely on their skin for structural integrity; zapping a hole in the side of a missile can cause it to tear apart under flight conditions. Aircraft are more robust, but underneath that thin, lightweight exterior are things like fuel tanks and critical electronics. So even if blowing a tank apart with a laser won't be an option anytime soon, many flying objects are fair game.
You may be wondering: If lasers do well against things slightly more delicate than tanks, what about stuff that's way more delicate than tanks — like people in general, or the human eye in particular? In one of those uncommonly rare turns of civility and common sense, most nations have foresworn the use of lasers to blind people, in the Protocol on Blinding Laser Weapons.
Long before lasers were used to melt holes in things, they were introduced on the battlefield as sensors, rangefinders, and target designators. It didn't take long for some smart spark long to figure out that 1) it would be really easy to permanently blind people with lasers, and 2) it would suck if a conflict generated unending streams of soldiers who were permanently blinded as soon as they hit the battlefield. "Join the Army! See the world! Very briefly!"
And so the militaries of the world decided that blinding soldiers with lasers was too dickish even for warfare. Granted, there is nothing that says you can't melt someone's hand off with a laser — but there's no way for a laser to do that while also being eye-safe. Therefore, anti-personnel lasers are pretty much off the table for everyone.
But they can still eff up missiles and whatnot. That said, if a laser takes even a few seconds to melt through the side of a flying thing, it's not going to work very well because your target would need to be super cooperative and not do anything like roll over, jiggle, or otherwise try to stop getting melted by your laser. Hence, what Lockheed has done in terms of increasing power is important: The less time it takes to melt a missile, the better.
Lockheed is demonstrating a technique called "spectral beam combining." In a nutshell, that involves combining several smaller beams into a larger one. Combining three 10 kilowatt lasers into a single 30 kilowatt output is easier and requires a lot less energy than making a single 30 kilowatt laser. And that's enough to melt the hell out of the manifold of a small truck engine.
Unfortunately for those in the military laser business, telling the public that you can zap through a specified thickness of aluminum at a certain range in 1.2 seconds instead of 1.9 seconds doesn't get you a lot of likes on Facebook. So these guys did what a lot of enterprising laser folks do: They developed a demonstration in which they melted the heck out of something to which the public can relate.
As Lockheed's press release puts it: "The ground-based prototype system burned through the engine manifold in a matter of seconds from more than a mile away. The truck was mounted on a test platform with its engine and drive train running to simulate an operationally relevant test scenario."
Can we expect to see the military using ground-based lasers like this to protect our shores from hordes of pickup trucks and/or technicals? Not any time soon, because that would be dumb. If you can hit a pickup truck with a laser, you can also hit it with a gun or a missile.
But this gets back to the fact that lasers are no slouch against comparatively flimsy airborne targets. Lockheed's press release about ATHENA mentions that it is part of the Area Defense Anti-Munitions (ADAM) system. That system is part of the broader family of what are called C-RAM (counter-rocket, artillery, and mortar) systems. In the interests of completeness, C-RAM systems can (at least in theory) be used as or are complementary to Very Short Range Air Defense (VSHORAD) systems used to blow away missiles and drones — at least in theory. Generally, C-RAM systems are used to defend an area, like a base, from unruly neighbors who keep lobbing rockets, artillery, and mortars at you.
Israel's Iron Dome is the best-known C-RAM system out there, and it has racked up quite a success rate in defeating the many explosive nastygrams launched from Gaza into southern Israel; Iron Dome uses missiles to intercept and destroy incoming rockets before they can hit anything. But the high-tech missiles that Iron Dome uses are far more expensive than the DIY redneck rockets used by Hamas; it takes an interceptor costing about $100,000 to blow a $1,000 Hamas rocket out of the sky — a 100 to 1 cost ratio in favor of the attacker. Even worse, a rocket-based C-RAM system can be overwhelmed by a sufficiently coordinated opponent who launches enough rockets to overwhelm the defenses.
Other C-RAM systems, like America's Phalanx or Germany's delightfully named Nächstbereichschutzsystem MANTIS, use Gatling guns that fire a thousand or more rounds per minute (in other words, 15 bullets per second). Those are considerably cheaper than the missile systems, but still aren't perfect.
And this is where lasers could really make their mark. Once you've eaten enough R&D investment to figure out how to get an operationally useful laser C-RAM system on the battlefield, the economics of playing defense change dramatically. Rather than having a C-RAM/VSHORAD system fire a $100,000 missile to take out a $1,000 rocket, they can use a laser to take out a $1,000 rocket for less than a buck. Now instead of a 100 to 1 cost ratio in favor of the attacker, it becomes 1,000 to 1 in favor of the defender.
Between the inability of lasers to blow up tanks, the general disinterest in using lasers to zap people, and lasers' exceptional ability to make bombardment an expensive and ineffective proposition for enemies, lasers may be shaping up to become one of the few weapons that actually ends up making warfare a bit less warlike.
Follow Ryan Faith on Twitter: @Operation_Ryan