A weapon that fires a beam hundreds of metres to induce unbearable pain is ready to be unleashed on the world – what should be done with it?

THE pain, when it comes, is unbearable. At first it’s comparable to a hairdryer blast on the skin. But within a couple of seconds, most of the body surface feels roasted to an excruciating degree. Nobody has ever resisted it: the deep-rooted instinct to writhe and escape is too strong.

The source of this pain is an entirely new type of weapon, originally developed in secret by the US military – and now ready for use. It is a genuine pain ray, designed to subdue people in war zones, prisons and riots. Its name is Active Denial. In the last decade, no other non-lethal weapon has had as much research and testing, and some $120 million has already been spent on development in the US.

Many want to shelve this pain ray before it is fired for real but the argument is far from cut and dried. Active Denial’s supporters claim that its introduction will save lives: the chances of serious injury are tiny, they claim, and it causes less harm than tasers, rubber bullets or batons. It is a persuasive argument. Until, that is, you bring the dark side of human nature into the equation.

The idea for Active Denial can be traced back to research on the effects of radar on biological tissue. Since the 1940s, researchers have known that the microwave radiation produced by radar devices at certain frequencies could heat the skin of bystanders. But attempts to use such microwave energy as a non-lethal weapon only began in the late 1980s, in secret, at the Air Force Research Laboratory (AFRL) at Kirtland Air Force Base in Albuquerque, New Mexico.

The first question facing the AFRL researchers was whether microwaves could trigger pain without causing skin damage. Radiation equivalent to that used in oven microwaves, for example, was out of the question since it penetrates deep into objects, and causes cells to break down within seconds.

The AFRL team found that the key was to use millimetre waves, very-short-wavelength microwaves, with a frequency of about 95 gigahertz. By conducting tests on human volunteers, they discovered that these waves would penetrate only the outer 0.4 millimetres of skin, because they are absorbed by water in surface tissue. So long as the beam power was capped – keeping the energy per square centimetre of skin below a certain level – the tissue temperature would not exceed 55 °C, which is just below the threshold for damaging cells (Bioelectromagnetics, vol 18, p 403).

The sensation, however, was extremely painful, because the outer skin holds a type of pain receptor called thermal nociceptors. These respond rapidly to threats and trigger reflexive “repel” reactions when stimulated (see diagram).

To build a weapon, the next step was to produce a high-power beam capable of reaching hundreds of metres. At the time, it was possible to beam longer-wavelength microwaves over great distances – as with radar systems – but it was not feasible to use the same underlying technology to produce millimetre waves.

Working with the AFRL, the military contractor Raytheon Company, based in Waltham, Massachusetts, built a prototype with a key bit of hardware: a gyrotron, a device for amplifying millimetre microwaves. Gyrotrons generate a rotating ring of electrons, held in a magnetic field by powerful cryogenically cooled superconducting magnets. The frequency at which these electrons rotate matches the frequency of millimetre microwaves, causing a resonating effect. The souped-up millimetre waves then pass to an antenna, which fires the beam.

The first working prototype of the Active Denial weapon, dubbed “System 0”, was completed in 2000. At 7.5 tonnes, it was too big to be easily transported. A few years later, it was followed by mobile versions that could be carried on heavy vehicles.

Today’s Active Denial device, designed for military use, looks similar to a large, flat satellite dish mounted on a truck. The microwave beam it produces has a diameter of about 2 metres and can reach targets several hundred metres away. It fires in bursts of about 3 to 5 seconds.

Those who have been at the wrong end of the beam report that the pain is impossible to resist. “You might think you can withstand getting blasted. Your body disagrees quite strongly,” says Spencer Ackerman, a reporter for Wired magazine’s blog, Danger Room. He stood in the beam at an event arranged for the media last year. “One second my shoulder and upper chest were at a crisp, early-spring outdoor temperature on a Virginia field. Literally the next second, they felt like they were roasted, with what can be likened to a super-hot tingling feeling. The sensation causes your nerves to take control of your feeble consciousness, so it wasn’t like I thought getting out of the way of the beam was a good idea – I did what my body told me to do.” There’s also little chance of shielding yourself; the waves penetrate clothing.

Raytheon is now building smaller versions for law enforcement or commercial maritime use – designed to be placed inside buildings, such as prisons, or mounted on ships for defence against, say, pirates. And soon there could be handheld versions of the pain ray. Raytheon has developed small experimental prototypes, one of which is about the size of a heavy rifle and is intended for police use.

Recently, other nations have begun to develop their own pain rays. While the US systems remain the most advanced, early research is also under way in Israel, and in 2012 the Russian government announced a plan to build their own version.

So why hasn’t the technology been used yet? Senior military leaders in the US have long argued that deploying the weapon for crowd control in hostile settings would prevent escalation of violence. It was shipped to Afghanistan in 2010, but was returned unused. And recently, a report by the US State Department argued that non-lethal weaponry could have helped prevent the 2012 assault of the US consulate in Benghazi, Libya, and recommended its introduction at similar outposts. Active Denial wasn’t singled out by name, but it would be the obvious choice.

The crucial unanswered question that has held back Active Denial until now is whether it could cause unanticipated effects on the body. So what does the evidence say?

Early AFRL tests in the late 90s explored the potential for burns, using a small laboratory set-up that exposed a few square centimetres of skin on volunteers’ backs. After-effects appeared to be rare and mild, so the testing programme was scaled up.

Since then, more than 11,000 people have been exposed to the beam. In total, the US Department of Defense claims there have been only eight burn injuries: six were pea-sized blisters, and the other two required medical care but recovered without complications. If these numbers truly reflect the reality, at less than one injury per 1000 exposures, this would seem to compare well against other non-lethal weapons, such as tasers. The US National Institute of Justice (NIJ) claims that three out of 1000 people experience significant injury from such electroshock devices. (It is worth noting that this statistic is disputed by manufacturers, and refers to use in the field, not controlled testing.)

What about other effects on the body? Could millimetre waves cause cancer? What is the effect on sensitive regions like the eyes or genitalia?

As non-ionising radiation, millimetre waves are relatively unlikely to be carcinogenic. Still, studies were carried out on mice over twelve weeks. The results, published in the journal Carcinogenisis, indicated that the radiation was not a cancer risk (vol 22, p 1701).

Peer-reviewed studies have also explored the effect on eyes – with and without glasses, contact lenses and goggles. These experiments, on primates, concluded that the eyes would have to be held open to cause damage, but the innate blink reflex when exposed to the ray makes that virtually impossible. As for reproductive organs, an additional study found no effects on sperm motility or morphology.

Further research has tested the potential impact in pacemakers, metal implants and similar medical issues, none turning up specific risks. Some of the testing has wandered out into the esoteric: a test to see whether drinking vodka increased the drinker’s tolerance to the pain, or whether wearing make-up made any difference – neither does.

This body of medical research has been scrutinised by various military expert panels. But perhaps the most persuasive review came from an independent group of academic researchers called the Human Effects Advisory Panel (HEAP), assembled to assess the quality of the science in 2002, 2004 and 2007. They concurred with the findings, concluding that Active Denial presents “a low probability of injury”. In fact, the panel reported that they were impressed by the research effort. As one HEAP member put it: “Other research endeavours should be so thorough.”

Nonetheless, some are continuing to object to the technology’s introduction. There is a potential for serious harm to human beings, they say, which no medical review could anticipate.

These objections were brought into focus in 2010, when local news media in Los Angeles reported that a prison, the Pitchess Detention Center, was about to try a new tool to break up fights between inmates. That tool was a civilian version of Active Denial developed by Raytheon, called the Assault Intervention Device. This variant of Raytheon’s pain ray technology was smaller than the military version – it was designed to be mounted on a ceiling in shared areas, with a beam 10 centimetres in diameter.

The organiser of the trial, Bob Osborne, former commander at the LA County Sheriff’s Department, says he was confident that it would reduce injuries in both inmates and prison staff. The methods currently used to deter inmates from brawling – batons or bare hands, usually – cause heavy bruising or even break bones, he says.

Indeed, an independent advisory panel convened by the US Department of Justice gave the Pitchess trial the green light on the basis that “the risks of injury due to the system are minimal”. The panel’s only mandate was that “specific and detailed” medical data should be kept on every use of the weapon. “We felt very comfortable recommending go ahead, with that caveat,” says Cynthia Bir at Wayne State University in Detroit, Michigan, a member of the panel.

Yet on the eve of going live, the trial was cancelled. It was not over health concerns, explains Chris Tillery of the NIJ’s Office of Science and Technology. Like Osborne and the panel, Tillery supported the trial. The test was shut down, he says, because of an unexpected outcry in the media and elsewhere about the potential for abuse of the technology.

And this goes to the heart of the moral dilemma raised by a technology that can induce pain invisibly. It may be medically safe if used properly, but in the wrong hands, it could also be a tool of oppression or torture.

Since the effects on the skin are usually invisible, the weapon’s use for torture or punishment could go unnoticed, or be denied outright. Jürgen Altmann, a physicist at the Technical University of Dortmund in Germany – one of the most vocal critics of Active Denial – has also pointed out that if the same person was repeatedly targeted in the same place in quick succession they could suffer from second-degree burns or worse. In fact, the problem of abuse had been raised long before the Pitchess trial was approved, but since every use was to be recorded, it was not considered an important enough factor to stop it going ahead.

Use and abuse

Experience with tasers suggests that abuse concerns are legitimate. Tasers have become a byword for excessive use of force by overzealous police officers. Not only that, numerous case reports – and YouTube videos – attest to such electroshock weapons being used on children, old people and peaceful protesters, not to mention animals. “The problem with tasers is that they are inherently open to abuse, as they are easy to carry and easy to use and can inflict severe pain at the push of a button, without leaving substantial marks,” says Angela Wright of Amnesty International.

She argues that non-lethal weapons like tasers should only be used as a last resort, as an alternative to firearms, and nothing less. This would rule out the proposed Assault Intervention Device in prisons from the start.

Given the controversy over potential abuse, it may well be that fear of lawsuits halted the Pitchess trial. “Cruel and unusual punishment” is explicitly mentioned in the Eighth Amendment to the US Constitution. And while the Assault Intervention Device was not intended to punish, a legal challenge is all too conceivable. Even a failed legal challenge would bring disastrously bad publicity.

The NIJ is now conducting a review of the use of Active Denial systems in domestic law enforcement, but until it announces its results, pain rays for non-military use in the US will remain on hold. Osborne is disappointed. He says the lengthy NIJ review process that is anticipated will effectively kill the prison project. “We will continue to have to use impact weapons that are virtually guaranteed to cause injury,” he says.

Non-lethal weapons like Active Denial cannot promise the bloodless resolution of conflict, but they do promise to make things a bit less bloody. Still, it is clear that there are no easy answers about if and when this technology should be used; about whether the potential for harm via abuse outweighs the harm avoided by replacing more damaging weaponry. The question facing those charged with making these decisions, then, is this: do we prefer an unpredictable world of pain, or the deadlier devil we know?

David Hambling is a writer based in London

http://www.newscientist.com/article/mg21829162.300-pain-ray-the-us-militarys-new-agony-beam-weapon.html?full=true