WASHINGTON: Lasers are déclassé even in science-fiction nowadays – the guys in Avatar and Mass Effect shoot bullets – and the big Air Force and Army laser programs of the last decade were ignominiously cancelled. So I was surprised at last week’s Navy League Sea-Air-Space conference to hear “directed energy” technology mentioned by no less a figure than Vice-Chief of Naval Operations Adm. Mark Ferguson as an area where the defense industry should invest.
In what is unlikely to be coincidence, the Navy’s new favorite think-tank, the Center for Strategic and Budgetary Assessments, had issued a report making the case for laser weapons just days before.
“DoD should support the U.S. Navy as the ‘first adopter’ for weaponizing an SSL [solid state laser] capable of producing a sustainable 100-plus kilowatt beam of laser energy,” the report declared. “Surface ships with sufficient power, space, and cooling are particularly well-suited as platforms for SSLs that could become part of an integrated network to defend against UAVs, cruise missiles, and fast attack craft.”
Why this coming together of lasers, the Navy, and CSBA? The Navy (and the Air Force) love CSBA because of its work on AirSea Battle, the intellectual armature for long-range air and naval operations across the vast Pacific in a future clash with China. But alongside the AirSea Battle concept, and indeed underlying it, CSBA’s collective obsession of much longer standing is the spread of smart weapons, once a Western monopoly but now proliferating to unfriendly states and even well-connected irregulars like the Iranian-backed Lebanese group Hezbollah. CSBA sees the spread of missiles as endangering America’s capacity to project power overseas: Even if they can’t reach the U.S. homeland, ballistic missiles threaten our forward bases, shore-launched cruise missiles our ships, surface-to-air missiles our planes, and anti-tank missiles our ground forces. Their biggest concern is that a well-funded adversary like China, or Iran on a more limited scale, could integrate these missiles into an “anti-access/area denial” system that can shoot down or sink US forces trying to approach, keeping American power at bay for fear of heavy casualties. AirSea Battle is all about defeating such a system.
While the US military has invested heavily on anti-missile defense, however, the current systems all shoot down incoming missiles by shooting other missiles at them. That’s the trail blazed by the famous Patriot missile system in the 1991 Gulf War – although the Patriot’s success rate against Iranian Scuds turns out to have been exaggerated – and followed by every other anti-missile system since, from the Ground-Based Midcourse Defense out in Alaska to the Standard missiles on Navy Aegis ships at sea. The technological problem here, as Dwight Eisenhower famously put it, is that trying to shoot down a missile with another missile is like “shooting a bullet with a bullet”: The target is about as fast as the system trying to intercept it, making a shoot-down difficult, and because interception is so technically difficult, an interceptor missile ends up costing at least as much as an incoming one, making defense expensive. In fact, CSBA’s report calculates that US interceptor missiles cost anywhere from $3.3 million apiece, for the latest Patriot, to $15 million, for the latest Standard, while a modernized Scud of the kind North Korea exports costs just $1 to $3 million each. That’s not just a budgetary problem, it’s a tactical one, because the defender may run out of missiles before the attacker does.
Lasers are – potentially – the answer for both parts of the “shooting a bullet with a bullet” problem. First and most obviously, laser beam moves at the speed of light, 671 million miles per hour, about 50,000 times faster than the fastest missile ever built. Even though the beam may have to stay on target several seconds to burn out the missile, that’s still a simpler targeting problem. Second and more crucially, once you’ve built your laser weapon, the cost of each shot is fairly low, and you can keep shooting as long as you have power. Instead of a limited number of expensive anti-missile missiles, an anti-missile laser enjoys effectively infinite ammunition. That reverses the current ugly equation, in which offense is cheaper and easier than defense, and makes defense feasible again.
Of course, that was the promise of the cancelled Air-Borne Laser (ABL) as well, an Air Force anti-missile laser that filled an entire Boeing 747 and never met expectations. That system’s biggest problem was that it consumed toxic chemicals to power each shot; not only did the laser require elaborate low-pressure piping to keep the chemicals in a gaseous state, but it eventually used the chemicals up and had to reload – undercutting lasers’ theoretical advantage of infinite ammo. The Army had its own chemical laser program, THEL (Tactical High-Energy Laser), which was also cancelled because the system took up several truckloads and was too hard to move.
CSBA thinks the chemical-laser approach is worth resurrecting for fixed defenses at American forward bases, where the system’s size and immobility would not be an issue: say, at the US Navy base in Bahrain, in easy reach of Iranian missiles, or the Air Force base at Osan, South Korea, in easy reach of both North Korea and China. After all, the easiest way to take out American airpower is not by shooting it out of the air, where it makes an elusive target, but by blowing up the big, immobile bases from which it must fly.
“DoD is pouring billions into advanced technologies, including stealth, to ensure our future air forces remain survivable–in the air,” argued the report’s lead author, Mark Gunzinger, in an email to Breaking Defense. “If their forward bases are not survivable, however…well, you get the point.”
But Gunzinger sees the most potential in what are called solid-state lasers, which use a permanent solid material, similar to fiber-optic cable, instead of expendable chemicals. A solid-state laser able to shoot down incoming missiles would still be big, because of power and cooling requirements, so the logical platform to mount one would be a Navy ship.
“By 2018, it should be possible for the Navy to field a ship-based solid-state laser to defend against anti-ship cruise missiles, aircraft including UAVs, and fast attack craft,” wrote Gunzinger. “Current-technology SSLs could be integrated into naval vessels such as the DDG-51 [Aegis destroyer], or even the LCS [Littoral Combat Ship].” Such laser ships would provide mobile anti-missile defense to US forces advancing against an “anti-access/area denial” system.
Ironically, lasers make lousy offensive weapons. The power requirements to burn through a bunker or an armored vehicle, as opposed to a relatively thin-skinned missile, are still well out of reach. And because lasers can only fire in a straight line, they’re actually an inferior form of artillery to old-fashioned howitzers, which can fire in a ballistic arc over a hill or over the horizon at targets they can’t see. (Gunzinger suggests bouncing laser beams off mirrored UAVs, but that adds a point of vulnerability that the enemy can shoot down). As defensive weapons against incoming missiles, however, lasers are the best option out there, if we can just get them to work – which, of course, requires an investment that everyone is reluctant to make in an era of shrinking budgets.