29 December 2005

Pain and Anxiety

Word on DefenseTech (see also MilitaryDOTcom and Wonkette) is that the Army wants to deploy the “Active Denial System” to Iraq essentially immediately. Pausing for a moment to penetrate the Orwellian name, I remind the reader that the ADS is a microwave system that looks like a prop from a Godzilla movie, and creates pain without (supposedly) actually cooking the target. The system is described at length at GlobalSecurity. The plan (dubbed Project Sheriff) is to send 15 truck-mounted systems to Iraq, while a more deployable airborne version is developed.

The system operates at 95 GHz. (That’s a frequency roughly 1,000 times higher than the FM band.) The beam is absorbed within the upper millimeter or so of skin; a 2 second burst raises the skin temperature to roughly 50°C. The burst is too short to burn, but it stimulates the nociceptors (more specifically, I am told, the C polymodal nociceptors) to produce an intense sensation of pain and a strong reflex to withdraw. The pain of a 5 second exposure is said to be intolerable.

The decision to get Project Sheriff under way was made by Army Col. Robert Lovett, the project manager for the Rapid Equipping Force, which tries to substantially reduce the time that it normally takes to get newly developed technology into the field. In an October 11 memo to the Deputy Undersecretary of Defense for Advanced Systems and Concepts, Col. Lovett asked to stop the ADS-1 ACTD (advanced concept technology demonstration – basically, a set of experiments to show that the system is not so risky as to threaten the budgets of future users), and redirect it to immediate deployment to Iraq. “System 1 capabilities have, to date, been sufficiently demonstrated in the ACTD to prove its value to the solider,” Lovett says in the memo. “System 1 current operating constraints can be mitigated if used in Iraq during the November through March time frame without modification.”

Operating constraints? Ah, yes. You’ve got a microwave oven, don’t you? When you cook a TV dinner, the instructions tell you to wait a minute after cooking, to allow the temperature to even out. Reflections within the oven produce zones of constructive interference where the microwave intensity is significantly above the average, and so the food gets extra hot. Of course, the bad guys aren’t in an oven, but there are still lots of opportunities for reflections and focusing. The operator has to be able to judge the power level required given the distance of the targets, while avoiding circumstances that could lead to unhealthy reflections (e.g., too many cars, shop awnings, etc.).

The ADS has been tested on human volunteers for several years. Details of tests in 2003 and 2004 were obtained under the Freedom of Information Act by Edward Hammond, director of the Sunshine Project. – an organization campaigning against the use of biological and non-lethal weapons. They were set up to prevent as much as possible any reflection or focusing – by excluding contact lenses and eyeglasses, and various types of buttons and zippers. Oh, and they took metallic objects (keys, coins, etc) away from the test subjects, to avoid hot spots – the same reason that you don’t leave a fork in the microwave. Even so, one volunteer was burned when the operator used the wrong power setting.

I have personal interest in this, because of my background in radio astronomy. These frequencies have been of interest to students of interstellar chemistry since the 1970s, because a number of the relatively simple molecules found in star-forming clouds have measurable emission in this range. (For example, the fundamental emission of carbon monoxide is at 115 GHz.) We observe them with telescopes equipped with fancy versions of FM receivers, mixing the celestial radiation with a nearby frequency generated by a local oscillator to produce much lower frequency signals that are easier to handle. Because the frequencies are so high, you can’t use wires, so the sky and local oscillator signals are piped together via hollow waveguides.

In the earliest receivers, the feed pipe carrying the sky signal was open to the outside, which meant that bugs could fly in and create excess noise. As the last step in tuning the receiver, we would often squint down the feed to check that it was clear. That stopped, though, when an engineer pointed out that half the radiation from the local oscillator was coming out the feed – right into the inquiring eye. He noted that prolonged exposure, even at such low power levels, might have long-term impacts, like tendency to cataracts.

Now, I’m not saying that those volunteers at Kirtland AFB are in trouble. I’m just saying that part of the infrastructure development in Iraq ought to involve training optometrists.


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