The U.S. Department of Defense wants to test a directed energy weapon in space, one that it hopes will someday destroy ballistic missiles moments after launch. The weapon, a so-called neutral particle beam, would be boosted into space and tested from orbit in 2023.
Neutral particle beams don’t get as much attention as lasers but are attractive in their own right. The weapons work by accelerating particles without an electric charge—particularly neutrons—to speeds close to the speed of light and directing them against a target. The neutrons knock protons out of the nuclei of other particles they encounter, generating heat on the target object.
Particle beams are effectively the “heat rays” or even “death rays” of science fiction. Unlike lasers, which burn the surface of a target, particle beams penetrate beyond the surface to affect its interior. This makes particle beams immune to measures that can deflect lasers, like brightly polished, mirror-like surfaces. A sufficiently powerful beam could generate enough heat to burn a target, igniting its fuel supply, melting it and rendering it aerodynamically unstable, or frying a missile’s onboard electronics.
A neutral particle beam requires an accelerator to produce the atomic or subatomic particles that make up the beam. The accelerator must produce a tremendous amount of particles in very short amount of time, then release them in a focused beam. A weaponized neutral particle beam would also need a power supply, a power storage system, and staging system to feed energy to the accelerator. Finally it would require an aiming system and either onboard sensors or communications links allowing it to take targeting cues from other space or air-based sensors or a centralized battle management system.
In 1989, as part of the U.S. Strategic Defense Initiative (“Star Wars”) the U.S. launched a neutral particle beam accelerator into space aboard a rocket. The (BEAR) project launched the accelerator from White Sands Missile Range to an altitude of 124 miles, where it successfully tested, “(neutral particle beam) propagation characteristics in space and the effects on spacecraft components.” The satellite was recovered intact after reentry.
, the Pentagon wants to test a neutral particle beam weapon from orbit in 2023. Officials believe technological advances over the past three decades make such a weapon more viable, especially the getting it small enough to launch into space part. Previous particle beam designs had large accelerators and power supplies, but officials believe they could probably design a weapon that could be launched into orbit. The Pentagon is holding the door open for the possibility such a system still isn’t doable, but is setting the goal for a 2023 test.
The Pentagon evidently hopes to use particle beams to destroy ballistic missiles for the so-called “boost phase intercept” missile defense role. Once launched, ballistic missiles swiftly accelerate through and beyond Earth’s atmosphere to low earth orbit. Once there, one or more individual warheads separate from the missile and then continue on their own trajectories to the same or separate targets.
Boost phase missile defense calls for shooting down ballistic missiles seconds after launch, while they are still accelerating, and before they have released their warheads. This simplifies matters greatly for the defender but has a number of problems, particularly getting the interceptor close enough to enemy territory to hit the missiles in time. The Pentagon evidently believes that space-based directed energy weapons—like lasers or particle beams—could react fast enough to shoot down ballistic missiles in the boost phase.
Will it work? There are a lot of technical issues that need to be resolved to make space-based particle beams work. The neutral particle beam will need to hold a coherent beam over the 1,000 kilometers or so from low-earth orbit to the ground. The system will need a sufficiently portable power supply. The Pentagon will need to figure out how to detect a launching missile, pass the data to a satellite, and then have that satellite engage the missile. It will also have to figure out how many satellites it will need, and since objects in low-earth orbit do not remain stationary, will need a fleet of satellites to ensure that one or more will be over the target in the event of a launch. These are all issues Washington wrestled with in the 1980s—and then failed to deploy a usable system. Only time will tell if things are different this time around.