Photo: Jack Thompson

TRUE BELIEVER: Harry D. Fair, director of the Institute for Advanced Technology, has for the past three decades championed research into electromagnetic guns. Refining the technology has proved thorny, but renewed interest in the United States, China, and elsewhere could finally lead to usable systems in the near future.

You have to be an optimist to work in this field, given all the tribulations you’ll inevitably encounter, day after day, year after year. If the EM gun community has an Optimist in Chief, it would be Harry D. Fair, director of the Institute for Advanced Technology at the University of Texas, Austin [see photo, “True Believer”].

Fair began working on electromagnetic launch in the mid-1970s. Back then he led a team of physicists at Picatinny Arsenal, the U.S. Army outpost in northwestern New Jersey responsible for building better guns. “We used to get together at the Mt. Hope Inn and talk over Reuben sandwiches,” he recalls. “We came to the conclusion that chemical propulsion had reached its asymptote” for both guns and rockets. What the Army needed was a radically new propulsion technology.

The key word here is “radical.” “We looked at catapults, storing energy in rubber bands. We called our discussions the ‘Nutty Ideas’ project,” Fair says, with a laugh. Eventually, two related technologies stood out, both based on electromagnetism: railguns and coilguns.

A railgun has few parts: a pair of parallel conducting rails inside a barrel, an armature that rides the rails, and a projectile in front of the armature [see diagram, “Gun Control”]. A jolt of dc current applied to one rail will travel up it, across the armature, and down its mate, completing a circuit and filling the gun’s barrel with an intense magnetic field. The barrel contains the pressure of this field, known as the Lorentz force, and so the only part that can yield to the pressure is the movable armature. The armature shoots out of the barrel, along with the projectile, at speeds as high as tens or even hundreds of kilometers per second—at least in theory. The most powerful conventional gun, by contrast, maxes out at about 2 km/s (about 4500 miles per hour).

The coilgun takes advantage of the fact that an electrical current flowing through a coil of wire creates a magnetic field. The barrel of a coilgun consists of one or more such coils, with a projectile in the center. The coils are powered on and off in succession, and each coil creates its own magnetic field; the field either pushes or pulls the projectile to the next coil. Timing is everything: if the coil energizes too soon or too late, it slows the projectile instead of accelerating it. A maglev train is a very long and very slow variation of a coilgun, although a coilgun requires a pulsed power source, whereas a maglev does not. One maglev design calls for jet engines instead of magnetic propulsion.

These ideas have been around since at least 1901, when a crowd gathered at the University of Oslo to witness the first public firing of a 6.5-centimeter-caliber, 4-meter-long coilgun, built by Kristian Birkeland. The test was suggestive of tribulations to come: a short circuit caused the gun to self-destruct in a burst of sparks and flame, and Birkeland soon turned his attention to fertilizer production.

During World War II the Germans and Japanese toyed with electromagnetic guns, with limited success. The German team built and tested the first large-scale railgun, which accelerated a 10-gram projectile to 1.08 km/s; however, the projectile melted in the process. The Japanese opted to develop a coilgun; though the plan was to project a 2-kilogram slug to a speed of 2 km/s, the machine achieved only 335 meters per second.

After the war, UK researchers tried to improve on the German railgun, while U.S. researchers investigated coilguns. The U.S. machine’s peak performance was to launch an 86-gram projectile at a speed of only about 200 m/s—even less than the Japanese had managed years earlier. At the 1957 Hypervelocity Impact Symposium, U.S. Air Force scientists bluntly concluded, “It is not likely that electro­magnetic gun techniques will be successful in the near future.”

None of that history deterred Fair and friends at the Picatinny Arsenal. They were tantalized by the possibility of using electromagnetic guns as an extremely cheap means of launching ­materials into space. To boost something just to low-Earth orbit by standard propulsion today costs upward of US $20 000 per kilogram. Their back-of-the-envelope calculations, by contrast, put the cost of EML at an astonishing $1 per kilogram. Even accounting for inefficiencies in the equipment, EM launches would be cheaper than chemical rockets by a factor of thousands.

Fair’s office shelves are still crowded with books about space flight—The High Frontier: Human Colonies in Space, by Gerard K. O’Neill, Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets, by John S. Lewis, to name a couple. But mining the sky had to wait, for even researchers with giant ambitions must go where the money is. And for nearly the entire history of EML, that has meant building systems that break things and kill people.