The U.S. military has been after self-guided bullets for years. Now, government researchers have finally made it happen: a bullet that can navigate itself a full mile before successfully nailing its target.

The breakthrough comes courtesy of engineers at the government's Sandia National Laboratories. They've successfully tested a prototype of the bullet at distances up to 2,000 meters – more than a mile. The photo above is an actual image taken during one of those tests. A light-emitting diode was attached to the bullet, showing the amazing pathway that the munition made through the night sky.

The lab's day-to-day operations are run by an auxiliary of Lockheed Martin. Of course, Lockheed's been a longtime partner in the military's quest for the ultimate self-guided munition. In 2008, they scored a $14.5 million contract as part of Darpa's "Exacto" program, which sought to develop sniper rifles with guided bullets. They've also been involved in the agency's "One Shot" initiative, which is trying to develop scope-mounted lasers that can help snipers compensate for weather conditions.

Each self-guided bullet is around 4 inches in length. At the tip is an optical sensor, that can detect a laser beam being shone on a far-off target. Actuators inside the bullet get intel from the bullet's sensor, and then "steer tiny fins that guide the bullet to the target." The bullet can self-correct its navigational path 30 times a second, all while flying more than twice the speed of sound.

The innovation involved some major changes to typical bullet design, which involves grooves inside the barrel to make the bullet spin and therefore fly in a straight line. Researchers had to eliminate that spinning to allow the bullets to twist and turn towards their target. Instead, they used those tiny fins – similar to those on a dart – to keep the bullet aloft while allowing it a full range of motion to navigate through the air.

Even with an ace marksman, researchers found that a typical unguided bullet – operating in real world conditions that might include crosswinds or changes in air density – would miss a target that was a half-mile away by nine meters. A guided bullet, however, could get within eight inches of that same target.

For a little more perspective, consider the world record in shooting accuracy: It currently belongs to British Army sniper Corporal Craig Harrison, who shot two Taliban operatives from a mile-and-a-half away. And Harrison performed that feat under "perfect" conditions.

[UPDATE]: Plenty of readers complained that the video accompanying this story didn't, you know, explain anything. Enter the delightful folks at Taiwan's Next Media Animation. They've created a helpful dramatic reenactment that sheds a little more light on how the military's self-guided bullets will ruin your next pleasure craft ride.

Photo/Video: Sandia National Laboratories; NMA