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Sunday, April 19, 2015

Fire the Lazor

A classic feature of science fiction for ages but laser weapons are likely coming up soon. Will we see the Phasers of Star Trek or the staple gun lasers of Space 1999 anytime soon, doubtful. But there more usefulness in the larger scale.


Get Ready: Laser Weapons Are Almost Here

The development of small, cheap lasers means that the era of real-life ray guns may be finally at hand.

May 1977 saw the premiere of an epic tale in which an evil empire deployed powerful directed-energy weapons in its quest for total domination. Star Wars was first shown in the same month, but Aviation Week’s serial scoops on the Soviet Union’s supposed development of laser-based missile defenses were a hit in their own right.

Inspired by ultra-hawkish Maj. Gen. George Keegan, just retired as chief of U.S. Air Force intelligence, they suggested that the Soviets were preparing to end the Cold War on their own terms—by threatening the West with destruction from behind a laser-powered shield. Within a few years, the Star Wars title had been co-opted for the Pentagon’s own Strategic Defense Initiative....

To quote the 1980s, "Like, wrong." Time Magazine titled it "Star Wars", not the Pentagon.

Talking about megawatt-class space-based lasers just 17 years after the first laboratory-bench laser was like expecting the Wright Brothers to build a 747. The SDI quickly found that only Darth Vader could make them work. Russia’s own space-based laser program—which in fact was a kludge, built in response to the SDI—crashed along with the 80-ton Polyus spacecraft in May 1987. The SDI’s impractical Airborne Laser lumbered on until 2011. The only thing of consequence that any of them destroyed was confidence in laser weapons.

Today, expectations and technology have converged—and practical high-energy laser (HEL) weapons may be close to combat-ready.

New HEL weapons are smaller than the 1980s monsters, with a goal of 100 to 150 kilowatts—less than a tenth of what the SDI had in mind—and powered by electricity rather than rocket-like chemical systems. Modest power permits more precise optics and—in some cases—the use of commercial off-the-shelf fiber laser sources, improving beam quality and reducing cost. (There are two vital statistics in laser weapons: One is raw power and the other is beam quality, or the ability to focus that power on a small spot at a distance of a kilometer or more.)

Star Wars lasers were intended to hit things that missiles could not touch. The new generation exploits different characteristics: a magazine as deep and easily replenished as the fuel tank, and a low cost per shot; Rheinmetall, a German arms company that’s developing a laser carried by an armored vehicle, says that each shot uses a Euro’s worth of energy—roughly, a dollar. They are designed to deal with targets that missiles can’t engage affordably.

A mini-drone, for example, doesn’t carry weapons but is a threat because it can target ground forces for artillery. It’s cheaper than any surface-to-air missile, but a laser can blind it, destroy its payload or shoot it down. Rocket and mortar defense is another application. The Iron Beam laser, being developed by Israel’s government-owned missile-make Rafael, is a logical follow-on to the Iron Dome missile system, which is practical and affordable only because it ignores rockets that will fall on open ground: That will no longer work when weapons are guided.

Close behind the systems already shown off by Rheinmetall, Rafael and Europe’s MBDA—certainly not a technological leap away—is the new “Gen 3 HEL” technology being developed by General Atomics Aeronautical Systems to fit on an Avenger unmanned air vehicle.

The company claims that the Avenger-carried version could combine 150 kW power with high-beam quality and that it can fire 10 times between 3-minute recharges. As well as arming the Avenger, it might fit in the 3,400-pound pod that Boeing designed for the Advanced Super Hornet, the next generation of its F/A-18 jet. A bomber or a special-operations C-130 could carry it easily. Other versions could put up to 300 kW on target, the company says, and a ground-based—but flight-weight—system is being prepared for its first tests outside the laboratory.

Why lasers? A magazine as deep as a fuel tank, and a low cost per shot. One arms company that’s developing a laser carried by an armored vehicle says that each shot uses about a dollar’s worth of energy.
This is a tipping point, because what you can do with 150 or 300 kW also depends on what you’re trying to protect. If the goal is to knock down a supersonic anti-ship cruise missile (the focus of some long-running Navy programs), there are two problems. Water in the atmosphere—whether humidity, rain or spray—attenuates laser energy, and a damaged cruise missile can still hit the target in the form of a ton of high-speed burning trash. But if the target being protected is an evasively maneuvering aircraft, it will often be in clear, dry air; and it is enough to destroy the missile’s seeker, put a hole in the radome or weaken the motor tube to cause a miss, even at well-sub-kilometer range.

Shooting a small, fast target is a laser’s forte, because what makes it new as a weapon is its instantaneous impact. The century-old basic air warfare problem—figuring out where the target is going to be when the bullet or missile gets there—is over.

Two laser-armed fighters in a formation could act as escorts, with 20 quick shots to defeat a pop-up threat. A bomber on a maritime strike mission would be able to penetrate the outer zone of a hostile fleet’s defenses. Countermeasures are expensive: mostly they mean trying to harden the missile, invariably adding weight.

Conversely, improving laser power and beam quality are engineering challenges, not alter-the-laws-of-physics problems. Something like a 500 kW, 2,000-pound weapon—just over twice the weight of an internal M61 Gatling gun, its feed system and ammunition—would mean another tipping point for air warfare. Provided that adaptive optics can be developed to fire the laser through friction-heated air, a moderately agile laser-armed supercruiser would be a tough target, whether or not it was stealthy. A laser fighter would not need extreme agility, either to put weapons on target or to evade enemy fire.

But the near- to mid-term developments will have an impact: Consider the reaction if, between now and 2020, a version of China’s long-lived, utilitarian H-6 medium jet bomber emerges with a functioning, fractional-megawatt missile zapper. It’s a lot more likely than orbiting strategic-defense lasers were in 1977—and could well cause panic on a similar level...

Cheaper and more effective. To quote the 80s again, "Like, cool!" :<)

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