The Army's eight-wheeled laser truck that zaps enemy missiles

Using lasers to shoot down missiles has long been one of the military's objectives, but implementing the technology has proven easier said than done. That may be changing: On Sunday, Boeing revealed the newest version of the HEL TD (High Energy Laser Demonstrator), a laser-equipped Army truck capable of shooting down all sorts of deadly projectiles in the blink of an eye. Here, a brief guide:

What is the HEL TD, exactly?

It's a heavy-duty, eight-wheeled, 500-horsepower, all-terrain truck that comes packing a 10-kilowatt solid-state laser system designed to blast missiles out of the sky. Boeing first revealed the HEL TD in June 2011, but recently added new components to make it more powerful.

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Why a laser?

It's hard to defend against short-range projectiles like rockets and mortars because they're often airborne for just a few seconds, "providing little time to take cover," says Damien Gayle at the Daily Mail. Using heavy artillery to knock them out of the sky might "inadvertently hit friendly forces in the process." A laser, on the other hand, which moves at the speed of light (186,000 miles per second), can zap enemy missiles with "unprecedented precision and swiftness" — as long as a source of electricity is nearby.

How powerful is this laser?

The HEL MD's 10-kilowatt laser is actually "fairly modest compared with the power levels the Pentagon aims to achieve," says Jonathan Skillings at CNET. The defense agency is aiming high, and hopes to build and implement 100-kilowatt "weapons-grade" lasers in the near future.

When will the HEL TD actually make it out onto the field?

Boeing's been testing similar technology for a long time. In May 2009, it shot down a handful of unmanned aircraft using lasers from its Matrix and Laser Avenger systems. And other defense contractors, like Raytheon and Northrop Grumman, are also working on similar anti-projectile systems based on light. As for the HEL MD, the system will be subjected to field testing for the next 12 months, and a final version of the laser truck is expected to be completed by February 2015.

Sources: CNET, Daily Mail, Optics.org, Ottawa Citizen