Washington (CNN) -- It wouldn't take much effort to hijack a drone over U.S. airspace and use it to commit a crime or act of terrorism, an aerospace engineering expert told a House subcommittee Wednesday.
Todd Humphreys showed members of a House homeland security subcommittee how his research team was able to commandeer an $80,000 drone using store-bought global positioning system (GPS) technology.
Drones, including ones used by police agencies, are vulnerable to hacking because they use unencrypted GPS information for navigation.
"If you can convincingly fake a GPS signal, you can convince an (unmanned aerial vehicle) into tracking your signal instead of the authentic one, and at that point you can control the UAV," said Humphreys, an assistant professor specializing in orbital mechanics at the University of Texas.
Humphreys said hacking and spoofing to take control of a drone can be done from miles away.
The U.S. military uses encrypted GPS on drones flying in war zones such as Afghanistan. To use similar technology on all drones would increase costs dramatically, according to Government Accountability Office (GAO) officials who attended Thursday's hearing on Capitol Hill.
GAO officials have suggested that the Homeland Security Department and the Federal Aviation Administration collaborate in regulating drones. But the Department of Homeland Security has, up to this point, been unwilling to accept a role in regulating drones, according to Rep. Michael McCaul, R-Texas.
DHS officials were repeatedly chastised by committee members for failing to show up for Thursday's hearing.
"The Department of Homeland Security mission is to protect the homeland. Unfortunately, DHS seems either disinterested or unprepared to step up to the plate to address the proliferation of unmanned aerial systems in U.S. airspace, the potential threats they pose to our national security, and the concerns of our citizens of how drones flying over our cities will be used, including protecting civil liberties of individuals under the Constitution," McCaul said.
Drones are currently a growth industry in the aviation sector, with scores of new companies competing for a slice of the market. And if they can clear hurdles that currently limit their deployment in friendly airspace, pilotless planes of all shapes will be taking to the air on missions to watch over us.
Just what sort of reconnaissance the drones will do and how such uses might infringe on civil liberties was a hot-button issue at Thursday's hearing.
Privacy advocates are seeking tighter regulation, arguing that anyone can purchase a drone and use it to peek into backyards and places that typically are private.
"We're looking at procedures...to make sure drone operators are not allowed to utilize their drones for purposes outside of what they were initially licensed for," said Amie Stepanovich of the Electronic Privacy Information Center, a privacy advocacy group.
"If we don't address this now, we believe that there will be a visceral reaction from the American public." Stepanovich said.