EVER watched Star Trek and wondered what it must feel like to be hit by a phaser set to 鈥渟tun鈥�? If you鈥檙e unlucky enough to be caught up in a riot in the future, you may well find out. Because the latest idea in non-lethal weapons is a laser that can knock you off your feet.
If it works, it could change the way the military and law enforcement authorities deal with civil disturbances. They claim that this laser is more accurate than plastic bullets, more controllable than tear gas and more flexible than either, and it can be fired accurately from up to 2 kilometres away.
It sounds like a triumph of innovation, yet no one wants to talk about it. Its developer, Mission Research of California, will not comment. The Institute for Non-Lethal Defense Technologies is silent on the matter. A leading scientist in the field says he is 鈥渘ot at liberty鈥� to discuss the topic. And he can鈥檛 even tell me why. The Joint Non-Lethal Weapons Directorate (JNLWD) at Pennsylvania State University is the driving force behind the project, yet it took five months to deliver a statement answering my questions. And it could hardly have been less informative.
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But the existence of the Pulsed Energy Projectile (PEP), as this weapon is called, is scarcely a secret. In the last financial year, US government budgets show that it received $3,173,000 in research funding.
Maybe no one wants to comment because of the way it works: the PEP will be a tough sell for any public relations team. If it鈥檚 fired at you, the laser vaporises the first thing it hits. That could be your shirt 鈥� or your skin. This creates a plasma that heats the surrounding air so fast that, basically, the air explodes. The resulting shock wave will knock you to the floor.
If it sounds like just another crazy military concept, it鈥檚 not. The PEP is now in the late stages of development and, judging from JNLWD documents, should hit the streets by 2006. The current plan is to mount the laser on a truck, plane or helicopter, fire it from a safe distance, and stop rioters, snipers or soldiers without risking harm to military personnel. In June, USAF Special Operations Command proposed converting a B-2 bomber so that it could perform vertical take-off and carry, among other things, non-lethal lasers to blast people, such as gunmen in crowds, from a couple of kilometres away. This airborne capability is something the US military has been seeking since the ugly scenes in Somalia in 1993 (see 鈥淔ire on the madding crowd鈥�).
Information about the PEP is extremely hard to come by. Halfway through researching this article, someone shut down the JNLWD鈥檚 online library. All US military websites are undergoing a 鈥渄etailed security review鈥� at the moment. But some clues come from the accountants鈥� trail (see 鈥淪how me the money鈥�) and if you look hard enough, you can glean some technical details.
The best source seems to be a report written by Harry Moore of the US Army Tank-automotive and Armaments Command, Picatinny, New Jersey. In 2000, Moore presented the PEP concept to a joint services meeting on small arms. His presentation is still available on the Internet ().
Moore鈥檚 report shows that the PEP wasn鈥檛 always so politically correct. It started out 10 years ago as the Pulsed Impulsive Kill Laser (PIKL) and came into being as a result of a stubborn problem encountered during the Strategic Defence Initiative (SDI) 鈥淪tar Wars鈥� programme. Part of the SDI plan was to use lasers to shoot down incoming ballistic missiles. But tests showed that, when a high-powered laser is fired at a metal target, the target absorbs far less energy from the laser than expected. The reason for this is the inverse Brehmsstrahlung effect.
Brehmsstrahlung 鈥� German for 鈥渟lowing down radiation鈥� 鈥� occurs when a moving electron is slowed down; part of its energy is emitted as a photon. The opposite, inverse Bremsstrahlung, happens when an electron absorbs a photon and speeds up.
When the laser first strikes the target it causes intense heating, vaporising the surface and creating a plasma, essentially a cloud of charged particles. This then absorbs the rest of the incoming laser light. The plasma gets hotter, but the target remains intact.
Shock tactics
Although the effect scotched the original aim of burning a hole in the target, SDI researchers reasoned that it could still be put to good use. At high energy levels, you get the shock wave effect generated by the PEP.
The discovery set off the PIKL programme to see whether this laser-created shock wave could do real damage. In 1992, the Los Alamos National Laboratory began developing a prototype laser, while the Air Force鈥檚 Armstrong Labs investigated the biological effects of infrared laser pulses.
The Los Alamos team built a deuterium fluoride chemical laser, firing pulses 3 to 5 microseconds long with an energy of more than 300 joules. It had a range of about 2 kilometres, and produced a detonation with two effects: mechanical shock and ablation (erosion of a layer) of the target surface. The target ablation was considerable. The laser produced a rapid series of pulses that could 鈥渓iterally chew through target material鈥�, according to the Moore report. So in 1998 Mission Research started work on the PEP鈥檚 precursor, the Pulsed Chemical Laser, the idea being to build a practical weapon for both lethal and non-lethal use.
The project was renamed the PEP in 2000, and it seems that the proof-of-principle chemical laser was good enough to make it worth developing an operational system. Again, details are hard to come by, but in the same year John B. Alexander, chairman of the National Defense Industrial Association Non-Lethal Defense Conference, gave an insight into its performance. Writing in National Defense magazine, he said the PEP鈥檚 effects include 鈥渁 dramatic flash, nearly deafening sound, and substantial kinetic impact鈥�. That impact, Alexander adds, is well above that of any beanbag round or plastic bullet. And in case one hit isn鈥檛 enough, Mission Research is developing a quick-fire 鈥淕atling gun鈥� version.
Alexander also mentions some of the PEP鈥檚 effects on a target鈥檚 body. They include pain, susceptibility to chemical agents (if skin is destroyed), lesions, temporary paralysis, choking, fibrillation and disorientation. According to J眉rgen Altmann, a physicist at the University of Dortmund and a specialist in the effects of non-lethal weapons, such effects would require 20 to 100 kilojoules per pulse. That鈥檚 a far higher energy than was used for the original bioeffects test. Whatever the energy of the current prototype, Altmann says, such a system must be assessed independently before it鈥檚 rolled out. He believes there鈥檚 nothing sci-fi about the PEP 鈥� he used to work with deuterium fluoride lasers and says the weapon is technically plausible. Whether it鈥檚 non-lethal, however, is another matter.
He speculates that the blast pressure from a hit in the mouth or nose, for example, could rupture a lung if the laser鈥檚 energy were set too high. An impact on the chest could damage internal organs. Of course, someone hit in the eye could be blinded, either with this or most of the existing laser weapons (New 杏吧原创, 7 September, p 5). But the PEP would be particularly vicious: the shock wave would be like having a grenade go off in your eye socket.
Altmann points out, however, that it鈥檚 impossible to make an intelligent judgement of the risks, or to find out what really happens if you are hit by this laser, as there鈥檚 simply not enough information in the public domain. The JNLWD didn鈥檛 answer my questions about the PEP鈥檚 effects on the body, and the Armstrong reports on the biological effects of the PIKL have never been circulated outside the military community. In the past, Leik Myrabo of Rensselaer Polytechnic Institute, Troy, New York, has helped journalists with this kind of enquiry. He has done a lot of work in the field of laser propulsion and I thought he鈥檇 be sure to know the kind of power needed for such a project. But he says he is no longer in a position to talk about military impulsive lasers and would not be quoted.
As a classified programme, the PEP has been subject to a high level of security, ostensibly to stop potential enemies from developing countermeasures. But it has also shielded the weapon from public scrutiny and the potential embarrassment of public testing. After all, it may not work in the field.
Don Walters of the Naval Postgraduate School in Monterey has carried out research into laser propagation and points out that dust or smoke could hinder the PEP. Pulsed lasers produce a very high electric field that can ionise the atmosphere along their path, particularly when the air contains particles such as dust. 鈥淭he intense field near the particle surface ionises the air, producing a plasma that absorbs and stops the laser energy,鈥� Walters explains. This has been a problem for high-powered pulsed lasers almost from the outset, and it is not clear how the PEP will overcome it. The JNLWD pointedly didn鈥檛 answer my question on this either.
So the PEP remains an enigma, barely visible behind its veil of secrecy. It exists, certainly, but can it work as a non-lethal weapon? We may not know if it鈥檚 ready, safe or in service until the first hapless soul is struck down in the street. If that鈥檚 you, do let us know how it feels 鈥� if you can.
Fire on the madding crowd
The US military feel they have good reason to develop something like PEP. They think it is just the kind of weapon that could have saved lives in situations such as the riots in Somalia in 1993.
A mob attacked UN troops in the capital Mogadishu, so US helicopters were sent in to help. Lacking a non-lethal option, they opened fire with 20-millimetre cannon, killing a number of women and children. Not long after, the Somalis were dragging dead US servicemen around the streets. The tragedy spurred the US drive for the ultimate non-lethal weapon.
Many existing non-lethal options for crowd control have inherent problems. Chemical weapons such as CS and CN gas and OC pepper sprays are indiscriminate and can be carried off on the wind. Also, their effects vary 鈥� some people are unaffected by them, while others suffer severe adverse reactions. And it鈥檚 difficult to guarantee that kinetic-energy weapons such as baton rounds or plastic bullets, rubber stingballs and bean-bag rounds won鈥檛 kill. To keep them non-lethal, baton rounds must have a low velocity and a large diameter 鈥� preferably large enough to prevent them penetrating an eye socket 鈥� to spread their impact over a greater area. But this gives a projectile with poor ballistic performance, increasing the chance of hitting an innocent person.
The US military now have more exotic options in development. One is the Active Denial System (ADS), basically a dish that fires a beam of 95 GHz microwaves at a crowd, heating people鈥檚 skin and forcing them to move away. The Air Force Research Laboratory (AFRL) in New Mexico tested it on human volunteers last year (New 杏吧原创, 27 October 2001, p 26) and plan to fit it to trucks or low-flying aircraft for use in peacekeeping situations or to control riots.
But the AFRL says the ADS won鈥檛 be used until its legality as a weapon has been reviewed. There鈥檚 also fierce opposition to the system: critics say the ADS could cause cancers, for instance, or blind anyone hit in the eye by it. Tests for such problems are being carried out on rats, and the AFRL is not expecting the ADS to be cleared for use before 2006. The PEP, an equally radical and controversial solution to crowd control, is likely to face the same hurdles.
Show me the money
The war against terror may have closed the door on many technological details of the non-lethal weapons programme, but published government accounts can still tell us a thing or two.
In the financial year 2002, the PEP project spent $3 million on developing hardware and assessing its effects on a likely target. Another $2 million is planned for next year. But this may be only the tip of the iceberg. Thanks to the war on terror, Special Operations forces received a lot of extra cash for technology development this year, up from $11 million last year to $62 million, with $55 million earmarked for a tactical lethal/non-lethal airborne laser to be ready for production by 2005.
Such a laser could be a device like the PEP, which can be used at low power to stun or at high power to kill. There are also proposals to harness the accuracy of high-powered lasers and use them as non-lethal weapons. The idea is that they could destroy weapons, tyres, communications aerials and so on without harming enemy personnel.
Some programmes, such as the Agile Target Effects programme, are funded by the US Army鈥檚 Classified R&D budget of $200 million. And airborne lasers could draw on the US Air Force鈥檚 more generous 鈥渂lack budget鈥�, estimated at $6.7 billion.
