Improvised explosive devices are one of the biggest threats to soldiers in Afghanistan and across the world. They unleash a shock wave that can travel about 1,000 feet per second and hit with a pressure of 100 pounds per square inch. The U.S. Army's standard-issue Kevlar combat helmet absorbs some of that force, but it isn't designed to protect the soldier's face from shock waves, which studies suggest can pass through the eyes, nose and mouth to the brain. Nor does it prevent a soldier's head from jerking around, which can cause brain damage. Fortunately, Army researchers are exploring new designs that could someday protect troops from these hazards.