Late last month, officials from the Army and from Boeing presented to the press what appeared to be a working version of a mobile laser cannon. Parked in front of an American flag was an eight-wheel, 19-ton heavy truck. Affixed to the top of that truck was a laser beam controller, used to aim and fire lethal rays of coherent light.

There was only one thing missing from this $38 million High Energy Laser Technology Demonstrator: the laser itself.

The actual ray gun is being built under an entirely separate Army program — one that won’t be complete for another five years. Integrating the truck and the laser together could take another year or two on top of that. In other words, don’t expect a working laser cannon until at least 2017.

The Pentagon devotes about $550 million annually to a mind-bending myriad of researching and development projects, all designed make lasers and other so-called “directed energy weapons” a reality. Some programs are for lasers tucked into bombers, like Darpa’s  High Energy Liquid Laser Area Defense System. Some are for ships. Others are for trucks. But they all have a common denominator: the blasters are still far from combat ready. At this rate, even the interminable Afghanistan war could well be over before America has any semblance of a ray gun arsenal.

For decades, military scientists promised that lasers were the weapons of tomorrow, just around the corner. But the vats of toxic chemicals used to power the lasers made them all-but-useless in a real-life war. So the Pentagon shifted its efforts about five years ago, to solid state, electric-powered lasers, which would be easier to carry into combat. In 2009, one of those lasers hit what’s believed to be battlefield strength, firing pulses of about 100 kilowatts. That’s like 1,000 lightbulbs, shining on exactly the same spot and in the same wavelength.

It was an impressive laboratory feat. It wasn’t something you could to take Afghanistan, however. Nor was there a vehicle that could carry the weapon to war. The laser was big, fragile, and required giant cooling units and generators to keep it blasting. So the Army started last year a “Robust Electric Laser Initiative,” or RELI, to squeeze that laser into something that could fit on a truck — and keep its cool and its power in combat.

The idea is to build a set of rugged modules that can covert 30 percent of their electric power into laser power. Chain four of these 25 kW modules together, and you should have the heart of a working laser weapon. Lockheed Martin, Raytheon, Northrop Grumman, and General Atomics all have introductory design contracts, worth $42 million all told. The final RELI modules are supposed to be done by 2016 or so.

Hauling those laser modules, the Army hopes, is a truck an awful lot like the one they showed off last month. On top is a beam control system. It not only lets the soldier in the truck’s front cab operate the laser, explains Army program manager Terry Bauer.

“It also takes light, conditions it, focuses and aims the light at whatever you’re shooting at,” he says. “Plus, it’ll take input from another sensor, telling you where to look for what you want to destroy.”

The High Energy Laser Technology Demonstrator, or HEL TD, truck will now roll out to the White Sands Missile Range in New Mexico. It’ll plug into a series of outside lasers there for testing. The first won’t be much stronger than a light bulb. Eventually, the Army will connect that 100 kW laboratory laser to the truck, and hopefully start zapping all kinds of munitions that today threaten American troops. Then it’ll wait for those RELI modules to get done. By 2018 or so, the Army hopes to be ready for a “decision point” (.pdf) about the laser, and whether it has an “Army application” or not.

Meanwhile, Darpa and the Air Force have their own electric laser weapon plans. The Pentagon’s mad science agency recently gave General Atomics a $40 million contract for what they hope is the final phase of the decade-long, $120 million effort to build a pair of laser modules that could generate 150 kW of laser power. Unlike the Army’s laser, this one pumps out a “continuous wave” (.pdf) of coherent light.

Weighing about 1,650 pounds combined, the modules would make the High Energy Liquid Laser Area Defense System about “ten times smaller and lighter than current lasers of similar power,” Darpa promises. Testing at White Sands could begin by late 2012, according to an agency memo (.pdf), where HELLADS will begin “demonstrating lethality against artillery, rockets, and missiles at tactically significant ranges.”

But HELLADS isn’t supposed to stay on the ground. It’s meant to be put into an aircraft — specifically, into the forward bomb bay of a B-1B bomber. The Air Force is busy, prepping the plane for its blaster. Exactly how long this Electric Laser on Large Aircraft program will take, and how much it will spend, isn’t entirely clear. But since ray guns in the sky have all kinds of issues — like turbulence, and that nasty boundary layer effect around an aircraft’s wing — that a ground laser would never encounter, it’s a fair bet that America’s laser-blasting bomber won’t be ready much sooner than its laser-blasting truck.

Photos: U.S. Army