When Navy Academy graduate Robert Heinlein wrote The Moon is a Harsh Mistress in 1966, he was perhaps the first writer to describe the operation of an electromagnetic railgun. The concept was not new, with a railgun like patent being issued in the U.S. in 1918. The power requirements and the inability to produce materials that could withstand the forces produced limited the concept until recently.
The United States Navy has a working model of a railgun. On October 31, 2011, it fired its 1,000th shot. The materials science and the ability to power such a weapon have caught up with the concept itself.
An electromagnetic railgun uses a magnetic field produced by two metal rails and the projectile to launch the projectile. The magnetic field cannot move the rails so the force is directed to the projectile. The projectile can leave the gun at extremely high speeds, many times the speed of sound. The offical speed is currently Mach 7.5 or 7.5 times the speed of sound, 5,760 miles per hour.
None of the projectiles will use an explosive. Their destructive potential is the combination of their mass and their speed. Kinetic weapons like this offer the advantage of reducing collateral damage that explosive weapons do not. In addition, the ships carrying the railgun would have no magazines filled with high explosive, improving their survivability in an attack.
Materials science and physics are at the heart of this research. The 1,000 shot railgun is six meters long and 50 millimeters in diameter. It is disassembled after every shot and examined for the effects from the shot. The components become very hot from the friction generated during the shot.
The eventual goal is the routine production of a 64 megajoule railgun that can be deployed on Navy ships. It would have a range of around 230 miles and a fired projectile would take less than six minutes to reach its target. The energy delivered to the target would be the equivalent of being hit by a 64 ton object traveling at 100 miles per hour.
The railgun offers even more reach. In theory, a properly constructed and well powered railgun could launch projectiles ballisticly, thousands of miles away, or even into space. Costs for projectiles will be far less than those for artillery shells, missiles and warheads. Deployment of even the simplest railgun is years away but the 1,000 shot is a milestone for this science fact.