Here's how the U.S. Air Force wants to hunt the next generation of its enemies: A tiny drone sneaks up to a suspect, paints him with an unnoticed powder or goo that allows American forces to follow him everywhere he goes – until they train a missile on him.

On Tuesday, the Air Force issued a call for help making a miniature drone that could covertly drop a mysterious and unspecified tracking "dust" onto people, allowing them to be tracked from a distance. The proposal says its useful for all kinds of random things, from identifying friendly forces and civilians to tracking wildlife. But the motive behind a covert drone tagger likely has less to do with sneaking up on spotted owls and more to do with painting a target on the backs of tomorrow's terrorists.

Effectively tracking foes has become a high priority – and deeply secret – research effort for the Pentagon, which has struggled at times to sort out insurgent from innocent in places like Afghanistan. The Navy has a $450 million contract with Herndon, Virginia's Blackbird Technologies, Inc. to produce tiny beacons to make terrorists trackable. The Defense Department has been pouring serious cash – $210 million that they'll admit to – to find advanced new ways to do this so-called "Tagging, Tracking and Locating" work, as Danger Room co-founder Sharon Weinberger noted in Popular Science last year.

The research she cataloged is as mind-boggling as it is varied. Ideas range from uniquely-identifiable insect pheromones to infrared gear that tracks people with their "thermal fingerprint." One company, Voxtel, makes tiny nanocrystals that can be hidden in clear liquids and seen through night vision goggles.

A 2007 briefing from U.S. Special Operations Command on targeting technology stated that SOCOM was looking for "perfumes" and "stains" that would mark out bad guys from a distance. The presentation listed a "bioreactive taggant" as a "current capability" next to a picture of what looks like a painted or bruised arm.

Another tracking technology is "smart dust" – a long-forecast cloud of tiny sensors that stick to target human or his clothes. And that seems to be what the Air Force wants its mini drone configured for.

The solicitation floats the idea of dropping a "dust-like" cloud of electromagnetic signal-radiating taggants, either on top of the target or in his path so that he'll walk into it. To do that, they'd need to either do some high-altitude "crop-dusting" of the target or launch a small munition that would blow out the taggant in mid-air when it was nearby.

It may be a signal that the smart-dust technology is at least feasible enough to plan a vehicle around. In her article, Weinberger notes that Darpa-funded researchers had drones that could drop clouds of taggants the size of a grain of rice as early as 2001.

It's hard to say for certain, but accounts of drone targeting tech from Taliban and al-Qaida leaders indicate that the current tracking beacons – which rely on radio frequency pulses, radar or infrared flashes – pale in comparison to some of the proposals. According to statements from a Pakistani Taliban commander, the U.S. gives local spies tracking "chips" in their cell phones in order to train Hellfire missiles on militants. The battery-powered infrared beacons that al-Qaida says it found spies using, are a well-known technology that dates back to at least 1984.

What form will the Air Force's dusting drone take? The Air Force states the design isn't set in stone – they're open to "other innovative methods" – so it's as-yet unformed. But the "References" section of the solicitation name-checks a 1997 study for Darpa, "Small Scale Propulsion: Fly on the Wall, Cockroach in the Corner," [pdf] which may contain some clues.

The study examines the feasibility of Micro Air Vehicles (MAVs) on the battlefield to deliver a payload of taggants or explosives and mentions that while animal-like robots would be great, the technology to replicate their movement isn't quite available yet. Al-Qaeda might want to keep an eye out for strange birds in the coming years, because one of the companies mentioned in the 1997 study as having promising MAV technology, AeroVironment, has been perfecting a robotic hummingbird that can fly remotely for up to 10 minutes.

Photo: divemasterking2000/Flickr

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