Another reason to be wary of increasing reliance on unmanned drones in the US: They could be easily hijacked by terrorists. A University of Texas researcher illustrated that fact in a series of test flights recently, showing that GPS "spoofing" could cause a drone to veer off its course and even purposely crash. This is particularly worrisome, given that the US is looking to grant US airspace to drones for domestic jobs including police surveillance or even FedEx deliveries.
"In 5 or 10 years you have 30,000 drones in the airspace," Professor Todd Humphreys tells Fox News. "Each one of these could be a potential missile used against us." That's because "spoofing," a new technology, can manipulate navigation computers—and practically anyone can have access to a spoofer, seeing as Humphreys built his very advanced model for just $1,000. Non-military drones are particularly at risk, because they will use civilian GPS—which is easier to manipulate, since it's not encrypted. (Read more drones stories.)