The Pentagon has a new secret weapon to neutralize sites containing chemical or biological weapons: rocket balls. These are hollow spheres, made of rubberized rocket fuel; when ignited, they propel themselves around at random at high speed, bouncing off the walls and breaking through doors, turning the entire building into an inferno. The makers call them "kinetic fireball incendiaries." The Pentagon doesn't want to talk about them, but published documents show that the fireballs have undergone tests on underground bunkers.

There are plenty of bombs which could destroy a lab, and bunker-busting weapons can tackle hardened underground facilities. But blowing up weapons of mass destruction is not a good idea. Using high explosives is likely to scatter them over a wide area, which is exactly what you want to avoid.

Two special high-temperature incendiary bombs — named "CrashPAD" and "Shredder" — were quietly rushed into service for the use against WMDs few years ago. CrashPAD is based on the Mk.84 bomb and is intended for soft targets; the BLU-119/B Shredder is a modified BLU-109 bunker-buster for hardened or underground targets. The filler for both is a combination of explosive and incendiary, which is more effective than explosive alone, but hardly safe. An explosion causes overpressure and releases a plume of hazardous material. However, without any explosive the incendiary will not be adequately dispersed.

The incendiary must also maintain the temperature for a prolonged period, to ensure that anything dangerous is destroyed. That means heating up the entire structure for more than just a few seconds. Existing incendiaries tend to burn fiercely but quickly.

One solution is replacing the standard explosive or incendiary with a load of kinetic fireballs, described in this proposal. Each fireball is a hollow spherical shell with a hole in it; when the inside is ignited, the hole acts as a rocket nozzle. The kinetic fireballs eject an extremely high-temperature exhaust which will heat up the surrounding volume to over 1,000 F within seconds. Their random ricocheting around ensures that they will fill any space they occupy, and they are capable of diffusing throughout a multiroom structure.

This really is rocket science. The inventor, Kevin Mahaffy, was an engineer at Air Force Research Laboratory's Rocket Propulsion Division, and spent three years as the Chief of the Motor Branch overseeing solid and hybrid rocket propulsion. Mahaffy's company, Exquadrum Inc., has received contracts from the Pentagon's Defense Threat Reduction Agency, or DTRA, which is tasked with tackling WMD threats.

The DTRA acknowledges that the fireball project progressed under an SBIR program completed in 2006. The culmination was a 2,000-pound BLU-109 bomb, filled with a payload of fireballs, and tested against a multiroom bunker. DTRA would not comment on any more recent developments. However, I discovered a later contract running from 2006 to 2008, which indicates that the fireballs were taken further — possibly into some kind of low-rate production. The DTRA declined to comment further and suggested that I try filing an Freedom of Information Act request — a polite way of telling me to go away. I contacted Mahaffy directly about the fireball technology, but he was understandably unable to comment even on uses not related to the DTRA work.

The kinetic fireballs might be an effective way of dealing with chemical and biological WMDs safely. They might also be effective against nuclear facilities, as again they can effectively spread destruction throughout a complex without breaking it open and spreading radioactivity.

Smaller fireball payloads have been suggested for shoulder-fired rockets and grenades for tactical use. The DTRA is known to be interested in a payload for the 84mm SMAW rocket launcher for agent defeat; at present, ground forces have no tactical options for dealing with a suspected chemical/biological lab operated by terrorists or others.

They might find other uses for the fireballs as a "low collateral-damage technology." A warhead filled with fireballs offers a way to take out all the occupants of a building without causing it to collapse, and without damaging any adjacent structures. No blast, no fragmentation. Of course incendiary weapons can cause media and political backlash, but as the increasing deployment of thermobarics has shown, this need not be an obstacle.

For the present kinetic fireball technology seems set to stay on the secret list. And if you're running a chem/bio weapons lab and assuming they won't risk attacking you — be afraid.

Photo: Gizmodo