Active denial system
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Active_denial_system".

Humvee with ADS mounted

The Active Denial System (ADS) is a non-lethal, directed-energy weapon developed by the U.S. military.¹ It is a strong millimeter-wave transmitter used for crowd control (the "goodbye effect"²). Informally, the weapon is also called pain ray.³ Raytheon is currently marketing a reduced-range version of this technology.⁴ The ADS is currently being considered for deployment in the Iraq War.

Effects

The ADS works by directing electromagnetic radiation, specifically, high-frequency microwave radiation at a frequency of 95 GHz⁵ (a wavelength of 3.2 mm), toward the subjects. The waves excite water molecules in the epidermis to around 130 °F (55 °C), causing an intensely painful sensation of extreme heat. While not actually burning the skin, the burning sensation is similar to that of a light bulb being pressed against the skin.⁵ The focused beam can be directed at targets at a range of just under half a kilometer, or about 550 yards.⁶ The device can penetrate thick clothing, although not walls.⁶

At 95 GHz, the frequency is much higher than the 2.45 GHz of a microwave oven. This frequency was chosen because, due to the stronger absorption of water at those frequencies, they penetrate the skin to a depth of less than 1/64 of an inch (0.4 mm),⁷ which is where the nerve endings are located.

A spokesman for the Air Force Research Laboratory described his experience as a test subject for the system:

"For the first millisecond, it just felt like the skin was warming up. Then it got warmer and warmer and you felt like it was on fire.... As soon as you're away from that beam your skin returns to normal and there is no pain."

Electromagnetic radiation cannot pass through a conductor, so the effect can be shielded by a conductive mesh or foil which forms electromagnetic shielding around the target.

While the effects can be unpleasant, ADS has undergone extensive testing since its inception more than 12 years ago. Research into whether or not the device will cause long-term health effects has been inconclusive. Many aspects of the research are classified, making independent evaluation impossible. The beam is designed only to affect an individual for a short moment, due to safety presets and features, but these settings can be overridden by the operator.⁸ According to a public release, there have been over 10,700 "shots" by ADS.⁹

The ADS is currently only a vehicle-mounted weapon, though U.S. Marines and police are both working on portable versions.^{citation needed}

Demonstration

A fully operational and mounted system was demonstrated on January 24, 2007, at Moody Air Force Base, Georgia. A Reuters correspondent who volunteered to be shot with the beam during the demonstration described it as "similar to a blast from a very hot oven - too painful to bear without diving for cover."¹⁰

Controversy

Closeup of a "Desk top" millimeter wave projector. This simulates the feeling of the ADS beam in a small dime-sized region.

The effects of this radio frequency on humans have been studied by the military for years, and much, but not all, of the research has been published openly in peer-reviewed journals. A listing of many of these articles can be found on the military Joint Non-Lethal Weapons Program ¹¹ website on the ADS page.¹²

The early methodology of testing, in which volunteers were asked to remove glasses, contact lenses and metallic objects that could cause hot spots, raised concerns as to whether the device would remain true to its purpose of non-lethal temporary incapacitation if used in the field where safety precautions would not be taken. Proponents of the system claim that these tests were early in the program and part of a thorough and methodical process to demonstrate the safety and effectiveness of the technology, which has now involved more than 600 volunteer subjects and some 10,200 exposures. As safety was demonstrated in each step of the process, restrictions were removed, and now, according to ADS proponents, there are no restrictions or precautions necessary for volunteers experiencing the effect.¹³

Critics cite that although the stated intent of the ADS is to be a non-lethal device designed to incapacitate temporarily, easy modifications or incorrect use by the operator could turn the ADS into a more damaging weapon that could violate international conventions on warfare (although at this time, ADS has gone through numerous treaty compliance reviews and legal reviews by AF/JAO, and in all cases complies with every treaty and law).¹⁴ Long-term exposure to the beam may cause more serious damage, especially to sensitive tissues, such as those of the eyes. Two people have received second degree burns after exposure to the device.¹⁵¹⁶ (The actual number of injuries, according to Dr. Stephanie Miller of AFRL/RHDR, is a total of eight—the two previously mentioned, and six others, who healed without medical intervention.)^{citation needed}

A recent news article criticized the sheer amount of time it is taking to field this system, citing the potential it had to avert a great deal of pain and suffering in volatile areas around the world.¹⁷

A "table top" ADS being tested

Silent Guardian

The defense contractor, Raytheon, has developed a smaller version of the ADS, named the Silent Guardian. This stripped-down model is primarily marketed for use by law enforcement agencies, the military and other security providers. The system is operated and aimed with a joystick and aiming screen. The device can be used for targets up to 550 m away.⁵

Michael Hanlon—who volunteered to experience its effects—described it as "a bit like touching a red-hot wire, but there is no heat, only the sensation of heat." Contrary to Raytheon's claims that the pain ceases instantly upon removal of the ray, Hanlon said that the finger he subjected "was tingling hours later."¹⁸

Contracts

On September 22, 2004, Raytheon was granted an FCC license to demonstrate the technology to "law enforcement, military and security organizations."¹⁹

On October 4, 2004, the United States Department of Defense published the following contract information:

Communications and Power Industries (CPI), Palto Alto sic, Calif., is being awarded a $6,377,762 costs-reimbursement, cost-plus fixed-price contract. The contractor shall design, build, test, and delivery a two to 2.5 megawatt, high efficiency, continuous wave (CW) 95 gigahertz millimeter wave source system. The contractor shall perform extensive modeling, simulation, experiments, and testing to the maximum capabilities of their facilities (which shall no less than one megawatt peak RF output) that will ascertain the final CW capabilities of the source. The contractor also shall provide input for the requirements for the government's test stand, which will serve as a full power facility in the future. At this time, $900,000 of the funds has been obliged. This work will be complete by January 2009. Negotiations were completed September 2004. The Air Force Research Laboratory, Kirtland Air Force Base, New Mexico, is the contracting activity (FA9451-04-C-0298).²⁰

See also

• Heat Ray
• Directed-energy weapons
• Radiation
• Long range acoustic device
• Area denial weapons, to prevent an adversary from occupying or traversing an area

References