Drones’ sci-fi glow masks complications

James Nicholson

Names like “Predator” and “Reaper” make drones seem like either nightmarish weapons of death controlled by unseen hands, or awesome tools of destruction to strike fear into our enemies, depending on what side of the argument you are on. But are drones infallible? Do they live up to their hype? An engineering team at UT led by  Aerospace Engineering professor Todd Humphreys revealed a glaring Achilles’ heel in drone navigation systems last June that could deconstruct their presumed near-mythical invulnerability.

As it turns out, drones do not use some esoteric location-mapping technique accessible only to the brightest aerospace and computer engineers; they use GPS — not much more sophisticated than the GPS in your smartphone — which receives radio signals from satellites in orbit around Earth and uses them to triangulate position. GPS receivers are vulnerable to manipulation by a technique called “spoofing.” 

Spoofing requires a transmitter no wider than your average desk top to send radio signals that are calibrated to match satellite signals in shape, though with slightly elevated intensity. Once the GPS receiver on the drone gets the new stronger signal, it will give this fake signal priority over its original signal, allowing the team with the spoofing device to trick the drone into going off course.

It is easy to see the initial implications of such a device. If terrorists or unscrupulous individuals were able to use spoofing to their advantage, drones would likely be rendered nearly useless, like blind airline pilots trying to make a landing. Worse yet, with adept maneuvering they could be used as blunt weapons, flying into aircraft and buildings on the ground. 

However, spoofing has limited effectiveness on U.S. military drones deployed overseas. Whereas your average American uses a free-form GPS system, the U.S. military uses a complex system of encryption to protect its drones. Thus it is unlikely that any terrorist group or criminal organization could get their hands on enough resources to successfully spoof those systems. 

Individual governments, on the other hand, do have the resources to take down a U.S. military drone in the right circumstances, and it is believed that Iran used a large array of spoofing signals to capture a Sentinel stealth drone on Dec. 4, 2011. If a country puts enough resources into it, even the most advanced drones in the world can be rendered useless by spoofing.

Drones employed by the highest echelons of the U.S. military and the CIA overseas are one thing, but those are not the only drones used in the US. Around 10 drones fly from Corpus Christi along the U.S.-Mexico border year-round, operated by the U.S. Customs and Border Protection agency. According to Humphreys, they probably do not employ the GPS encryption system used by their cousins overseas.  As a result, they’re open targets for spoofing.

Spoofing devices are not easy to make; the one used by UT took three Ph.D.s three years and $1,000 to build. But it’s getting easier. Through software-defined radio, Humphreys says that the difficulties in creating a spoofing device will become “a coding issue, not a radio issue.” As the technology spreads, it will be less about technical pitfalls than an individual coder’s ability to work the system.

At the moment, however, the U.S. drone program is state-of-the-art, and its issues are moral rather than technical. As the United Nations investigates the legality and civilian casualties incurred by drone strikes, and a previously classified Justice Department memo detailing the U.S. government’s defense of the drone program was leaked to the public, it seems like the drone program is becoming as much of a problem as it is an asset. Though drones might seem like the weapons of the future, we need to consider seriously whether their benefits outweigh their moral, legal and technical hurdles.

Nicholson is an archaeology freshman from San Antonio.