Active Denial System
The Active Denial System is a directed-energy weapon developed by the U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it works by heating the surface of targets, such as the skin of targeted human beings. Raytheon had marketed a reduced-range version of this technology. The ADS was deployed in 2010 with the United States military in the Afghanistan War, but was withdrawn without seeing combat. On August 20, 2010, the Los Angeles Sheriff's Department announced its intent to use this technology to control incarcerated people in the Pitchess Detention Center in Los Angeles, stating its intent to use it in "operational evaluation" in situations such as breaking up prisoner fights. As of 2014, the ADS was only a vehicle-mounted weapon, though U.S. Marines and police were both working on portable versions. ADS was developed under the sponsorship of the Department of Defense Non-Lethal Weapons Program with the Air Force Research Laboratory as the lead agency. In 2014, there were reports that Russia and China were developing their own versions of the Active Denial System.
Mechanism and effects
The ADS works by firing a high-powered beam of 95 GHz waves at a target, which corresponds to a wavelength of 3.2 mm. The ADS millimeter wave energy works on a principle similar to a microwave oven, exciting the water and fat molecules in the skin, and instantly heating them via dielectric heating. One significant difference is that a microwave oven uses the much lower frequency of 2.45 GHz. The short millimeter waves used in ADS only penetrate the top layers of skin, with most of the energy being absorbed within 0.4 mm, whereas microwaves will penetrate into human tissue about.The ADS's effect of repelling humans occurs at slightly higher than, though first-degree burns occur at about, and second-degree burns occur at about. In testing, pea-sized blisters have been observed in less than 0.1% of ADS exposures, indicating that second degree surface burns have been caused by the device. The radiation burns caused are similar to microwave burns, but only on the skin surface due to the decreased penetration of shorter millimeter waves. The surface temperature of a target will continue to rise so long as the beam is applied, at a rate dictated by the target's material and distance from the transmitter, along with the beam's frequency and power level set by the operator. Most human test subjects reached their pain threshold within 3 seconds, and none could endure more than 5 seconds.
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.
Like all focused energy, the beam will irradiate all matter in the targeted area, including everything beyond/behind it that is not shielded, with no possible discrimination between individuals, objects or materials. Anyone incapable of leaving the target area would continue to receive radiation until the operator turned off the beam. Reflective materials such as aluminum cooking foil should reflect this radiation and could be used to make clothing that would be protective against this radiation.
Following approximately ten thousand test exposures of volunteers to ADS beams, a Penn State Human Effects Advisory Panel concluded that ADS is a non-lethal weapon that has a high probability of effectiveness with a low probability of injury:
- no significant effects for wearers of contact lenses or other eyewear
- normal skin applications, such as cosmetics, have little effect on ADSʼs interaction with skin
- no age-related differences in response to ADS exposures
- no effect on the male reproduction system
- damage was the occurrence of pea-sized blisters in less than 0.1% of the exposures.
Safety studies
Many possible long-term effects have been studied, with the conclusion that no long-term effects are likely at the exposure levels studied. However, overexposures of either operators or targets may cause thermal injury. According to an official military assessment, "In the event of an overexposure to a power density sufficient to produce thermal injury, there is an extremely low probability that scars derived from such injury might later become cancerous. Proper wound management further decreases this probability, as well as the probability of hypertrophic scarring or keloid formation."- Cancer: A mouse cancer study was performed at two energy levels and exposures with a 94 GHz transmitter: a single 10-second, 1 W/cm2 exposure, and repeated 10-second exposures over a two-week period at 333 mW/cm2. At both energy levels, no increase in skin cancers was observed. No studies of higher energy levels, or longer exposure times have been performed on millimeter-wave systems.
- Cornea damage: Tests on non-human primate eyes have observed no short-term or long-term damage as the blink reflex protects the eye from damage within 0.25 seconds.
- Birth defects: Millimeter waves only penetrate 0.4 mm into the skin, making direct damage to the testes or ovaries impossible.
- Blisters and scarring: Pea-sized blistering due to second degree burns occurred in a very small minority of tested exposures, which have a remote potential for scarring.
ADS Safety Studies have been independently reviewed by a non-government human effect advisory panel.
History
Development
Two Active Denial Systems were developed under a Defense Department "Advanced Concept Technology Demonstration" Program from 2002 to 2007. Unlike typical weapons development programs in the Defense Department, ACTDs/JCTDs are not focused on optimizing the technology; rather they are focused on rapidly assembling the technology in a configuration suitable for user evaluation.Contracts
On September 22, 2004, Raytheon was granted an FCC license to demonstrate the technology to "law enforcement, military and security organizations."On October 4, 2004, the United States Department of Defense published the following contract information:
Demonstration
The military has made the ADS available to the media for demonstrations on a number of occasions. A fully operational and mounted version of the system was demonstrated on January 24, 2007, at Moody Air Force Base in 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." An Associated Press reporter who volunteered to be engaged stated "They certainly convinced me that the system could help save the lives of innocent civilians and our young service members". A CBS News correspondent did an in-depth story on ADS in March 2008. A demonstration was conducted for the media on March 9, 2012, at Marine Corps Base Quantico, Virginia.Afghanistan deployment
On June 21, 2010, Lt. Col. John Dorrian, a spokesman for the NATO forces commander General Stanley McChrystal, confirmed in an e-mail to Wired reporter Noah Shachtman that the ADS was deployed in Afghanistan. The spokesman added however that the system had not yet been used operationally.The ADS had been removed from service in Afghanistan by July 19, 2010. A former Principal Deputy Assistant Secretary of Defense noted that the recall of ADS from Afghanistan was an "opportunity missed" and "the non-lethality of the ADS system could prove useful in a counterinsurgency operation where avoidance of civilian casualties is essential to mission success."
Potential deployment against civilians
In September 2020 it was revealed that federal officials had explored the use of the device and the Long Range Acoustic Device to disperse civilians protesting outside the White House in June of that year, but had been advised that the National Guard was not currently in possession of either device.Additionally, In August 2020, it was revealed that the use of the device had allegedly been considered in 2018 on the Mexico-United States border to prevent further illegal immigration. However Kirstjen Nielsen, then secretary of homeland security, rejected any use of the device, and forbade it being discussed again. This was reported on by the New York Times following information from two former officials, however a spokesperson would deny those claims.