Laser Weapons – Warfare at light speed DOWN THIS tiled corridor, light does muscular, noisy work. Lasers dig dirt and weld metal. They pound aircraft parts into shape. In Bob Yamamoto’s lab, light devours. He straps on emerald green goggles. A technician stabs a fire button and calls out the computer countdown. “Three … two … one …” Then … nothing. Just a buzz of electronics and an ephemeral glow in this darkened room at Lawrence Livermore Laboratory. But inside Yamamato’s target chamber, a block of steel spits flame and molten metal. In those two seconds, 400 blasts of light poured into slabs of clear, manmade garnet. Swollen in energy, the crystal’s atoms then unleashed torrents of infrared light to ricochet 1,000 times between two mirrors and multiply, finally escaping as 400 pulses of pure, square beam. Kilowatt for kilogram, this is the world’s most powerful solid-state laser. Its invisible beam drilled Yamamoto’s inch-thick steel plate in two seconds. Add larger crystals and it will eat steel a mile or more away. “What we’re building,” Yamamoto explains, “is a laser weapon.” After sinking 40 years and billions of dollars into beam weapons, defense scientists are on the cusp of what could be a military revolution — warfare at the speed of light. “We’ve made a quantum leap here,” said Randy Buff, solid-state laser program manager for the U.S. Army’s Space and Missile Defense Command. “We’re anxious to get out there and do something.” No longer are laser guns the stuff of Hollywood and Strategic Defense Initiative fantasy. Instead of laser-guiding bullets and “smart” bombs, the Pentagon inside of a decade could be armed with a beam weapon that is near-instantaneous, gravity-free and truly surgical, focusing to such hair-splitting accuracy that it could avoid civilians while predetonating munitions miles away. A laser arms race already is under way, chiefly in California. The prize is billions of dollars. Three families of high-energy beams — powered by combusting chemicals, electron accelerators and crystals, such as Yamamoto’s — are vying for the Pentagon’s eye. Defense contractors are sniping at each other’s designs, and corporate alliances are shifting. But no one seems to doubt that battle lasers — perhaps mounted on Humvees, jet fighters and unmanned aircraft — could knock down previously untouchable targets such as artillery shells, mortars, surface-to-air missiles and even cruise missiles at ranges of up to dozens of miles in good weather. In clear air above the clouds, a high-powered laser could lance out 500 miles to destroy rising ballistic missiles. “If we had them today, they’d be at the former Saddam Hussein International Airport, making sure no one gets off a shoulder-launched missile at an aircraft,” said Mike Campbell, a laser expert at General Atomics in San Diego. By coaxing a huge power boost out of tiny laser diodes like those in CD players, scoreboards and supermarket scanners, scientists are squeezing unprecedented power out of lasers made of exotic crystals — distant cousins of the world’s first laser, which Theodore Maiman fashioned from a ruby cylinder in 1960. The latest breed of solid-state lasers now are poised to break the dominance of giant, chemical gas-powered beams with compact, mobile weapons that can run off a Humvee’s diesel engine or a jet fighter’s turbine. Experts liken this evolution to the shift from 1950s vacuum tubes to the solid-state transistors now driving everything electronic. “We think the whole thing’s going to go solid state,” said Lloyd Hackel, chief of laser science technology at Livermore Lab. “Gas lasers are sort of the vacuum tubes of lasers. They work, but in terms of density, intensity and reliability, it’s going to go solid state.” No coherent military plan The Pentagon’s economic power places the military at the decisive center of this transition. So far, however, experts say the Defense Department has no coherent plan for speed-of-light weapons research, scattering projects among the Air Force, Army and Navy. As an offshoot, few in the Pentagon are grappling with the implications of highly mobile laser forces: Are military computers and commanders ready for entirely automated weapons that deliver instant, lethal blasts of energy and can be retargeted in seconds? Lasers under testing for air defense already offer that capability. Fully automated firing on offensive targets is a short step behind. “When you develop the capability to track, target and destroy something in a second, then the temptation to remove humans from the decision cycle becomes very great,” said Loren Thompson, chief operating officer at the Lexington Institute, an Arlington, Va.-based defense think tank. Will U.S. forces fire lasers on humans? International treaty forbids the use of lasers for blinding people. But there is no legal ban on striking humans. U.S. Special Operations Command wants to load a medium-power laser alongside artillery and miniguns on a future version of the AC-130 gunships that since Vietnam have been a mainstay of special forces attacks on ground targets. The laser’s power could blow tires and ignite gas tanks, but wouldn’t be lethal for tanks or armored vehicles. “It would be a very long-range, ultra-accurate sniper rifle,” suggests John Pike, a weapons expert and director of GlobalSecurity.org. The likely targets, Thompson said, “would be some sort of lighter vehicle or combustible structures or it could be people. Remember we’re talking about a system that can be instantenously retargetable.” Will the payoff of battle lasers sufficiently outweigh their huge drawback — loss of power and range in bad weather, fog, dust and smoke — that the U.S. military will shift toward fair-weather operations? Is the United States willing to defend or attack satellites with lasers? The Air Force’s Airborne Laser is to start test-firing against missiles in 2004. But the longer range of its laser in the thinner, upper atmosphere brings space vehicles within targeting. How will other nations respond? Experts believe the United States could enjoy a near monopoly on battle lasers for years. But under what circumstances will it justify their use in the face of likely international opposition? Well before the end of the Cold War, Pentagon technocrats talked of “transformation” of the military — a fusing of electronic eyes, fast communications and data crunching with precision weapons to wage war at hyperspeed and high efficiency. But despite compressing the time to identify and attack adversaries, U.S. weapons are still chained to the slow, Newtonian physics of explosives, chemical propellants and metal projectiles, and are still restrained by gravity. Ballistic warheads can strike at speeds greater than Mach 20. But readying them for launch takes several minutes at least and delivering them several more. Lasers race to target at roughly Mach 860,000. “There’s no problem with dodging the bullet,” said the Lexington Institute’s Thompson. With that allure, the Bush administration has specified that the signature vehicles, aircraft and vessels of the next-generation military accommodate futuristic weapons. Defense contractors are shoehorning laser bays into future fighters, tilt-rotor aircraft and helicopters. Humvees are going to hybrid diesel engines, and the Navy’s new DDX destroyer to all-electric drive. The military wants to cuts its logistical burden of fuel supply, but a secondary reason is extra electrical power for energy weapons. “They would have substantial surplus capability for some power-hungry weapon of the future, and whether that would be a laser or a microwave gun or a rail gun isn’t certain,” said GlobalSecurity’s Pike. The era of battle lasers began in the mid-1990s, when military scientists in New Mexico burned a hole in a Scud missile standing miles away. Soon after, a powerful chemical laser funded by the Pentagon and the Israeli Defense Force began blasting rockets and artillery shells out of midair. Scientists think such lasers have promise for knocking down mortar shells. Mortars and artillery are so lethal for infantry that they account for nearly half of U.S. combat deaths in Iraq. But no effective defense exists. ‘Let your imagination go’ “Nobody thought that could be done,” said Josef Scwartz, program manager for the Mobile Tactical High Energy Laser at Northrop Grumman. “Everybody thought you’d just hide in a hole. Now you have the ability to shoot it out of the sky. And if you can do that, you can let your imagination go.” Defense theorists already are performing computer simulations of laser battles. “What it does is change the battlefield,” said Thomas McGrann, a military operations analyst who runs battle simulations in Livermore Lab’s Q Division. “What we’re seeing is, he fires something at me, I knock it down. Anywhere from one to three kilometers out, I’m going to suppress his fire. And when he sends his UAVs (unmanned aerial vehicles) up — and they’re hard targets to kill — I can take them out. An Army guy says he’s taking fire from a wooded hillside. We start a fire there.” But forget about “Star Wars” and blaster pistols knifing the air with multi-colored beams. Visible lasers so far don’t pack sufficient punch over distance to be useful weapons. The laser battlefield will be largely invisible. Targets will explode, break apart in midair or burst into flame without apparent cause. Soldiers won’t buckle themselves into a laser cannon. The earliest battle laser systems are designed to defend U.S. troops and aircraft against airborne shells and missiles. That means computerized systems for tracking, targeting and firing faster than humans can react. And the world’s first laser weapons won’t be worn on the hip: The most technically mature candidates are sprawling monstrosities weighing 50 tons and filling the better part of a Boeing 747 or, in the case of Northrop’s MTHEL, a full-sized drug store, backed by chemical tanks or factories to recharge the lasers. That’s been the story of laser weapons for years. Chemical lasers are proven at delivering high-powered beams at great distances — if they have enough chemicals. Scwartz’ challenge is shrinking its laser by a fifth, to fit inside two cargo containers, packed inside a C-130 cargo plane. “Can we do it?” he said. “We think we can.” But some Army officials are wary of hauling tanks of flammable, toxic chemicals into a war zone. A former Pentagon official noted that a .50-caliber armor-piercing/incendiary bullet could ignite a toxic explosion. Once the laser stops firing, it must vent hot chemicals. That chemical and thermal signature could make a weapon traveling in two tractor trailers a conspicuous target. Ultimately, battlefield lasers will have to be more compact, mobile enough to fit in the tail of the helicopter, in the belly of a jet fighter or in the backseat of a Hummer. “Solid-state lasers seem to be the ideal for laser weaponry,” Thompson said. “The basic design seems to be less complicated than either free-electron or chemical lasers and it seems to be more easily incorporated, say, into a fighter. They have more potential over the long run because of their potential compactness and the flexibility of their power sources.” The most powerful electric laser is taking shape in Yamamoto’s lab at Lawrence Livermore, where pursuit of hydrogen fusion has produced two generations of laser jocks and the world’s most powerful solid-state lasers. “If you want something small enough and light enough to put on a Humvee or the back of a copter and have enough oomph to do something, the way to do it is a solid-state laser,” Yamamoto said. Experts agree battle lasers need at least 100 kilowatts of power. The Pentagon wants to see who will get to 25 kilowatts first in 2004. Yamamoto is a veteran builder of lasers and atom smashers. Next to those, the laser weapon sitting on his lab bench is easy: It’s modular. He just adds another 4-inch slab or two of manmade garnet and surrounds it with diodes. He expects to beat 25 kilowatts by Christmas and double it early next year. To reach 100 kilowatts will take more and bigger slabs. Yamamoto’s problem is heat. Lasing makes the crystals warm inside and corrupts the light beam. Eventually, the slabs can crack and shatter. They’re thick and don’t cool well in chilled water or gases. Livermore’s laser designers had a simpler idea: Build two or more of the compact lasers in cassettes and rotate them when hot. A leap in efficiency But the real innovation that makes solid-state lasers worthwhile for defense are high-power diodes. Instead of using flashlamps like Maiman’s ruby and the National Ignition Facility, Yamamoto’s laser is pumped by more than 8,000 diodes. They’re 10 times as efficient. In theory, that means a liter of everyday Army diesel fuel costing as little as $1 will generate enough rapid-fire laser pulses to destroy a standard airborne missile. The job now falls to Patriot missiles costing $3 million apiece. The question is, will solid-state lasers that today resemble science projects, full of glass, mirrors and banks of sensitive electronics take the beating of battle? “You have to get these lasers out in the field to see if they work. If you hit a bump in the road, do they hold up? Do you need five Ph.D.s to make them work?” said General Atomics’ Campbell. Moreover, all laser guns will, for the forseeable future, remain fair-weather weapons. Airborne particles and vapor diffuse the beam and cut its range enormously. Smart adversaries will attack under cover of smoke or inclement weather. “In the first order, lasers are not going to work on bad days,” Campbell said. “They’re just not.” But then, neither do so many of the optical sensors on which U.S. forces depend for information-accelerated warfare. “I’m sure there will be many games to be played in measures and countermeasures and counter-countermeasures,” said Northrop’s Scwartz. But the rule of thumb is “if you see a target, you can kill that target.”