Thanks to activists like Robert Greenwald and his new film Unmanned: America’s Drone Wars, many Americans are well aware of the ominous threat of weaponized aerial drones. Few, however, know that the United States Navy also has a drone program. From TIME Swampland:
While you were out shopping Sunday for those last-minute holiday gifts, the Navy pushed ahead with its own vision of an underwater sugar plum: a fleet of “long endurance, transoceanic gliders harvesting all energy from the ocean thermocline.”
And you thought Jules Verne died in 1905.
Fact is, the Navy has been seeking—pretty much under the surface—a way to do underwater what the Air Force has been doing in the sky: prowl stealthily for long periods of time, and gather the kind of data that could turn the tide in war.
The Navy’s goal is to send an underwater drone, which it calls a “glider,” on a roller-coaster-like path for up to five years. A fleet of them could swarm an enemy coastline, helping the Navy hunt down minefields and target enemy submarines.
Unlike their airborne cousins, Navy gliders are not powered by aviation fuel. Instead, they draw energy from the ocean’s thermocline, a pair of layers of warm water near the surface and chillier water below.
The glider changes its density, relative to the outside water, causing the 5-foot (1.5m)-long torpedo-like vehicle to either rise or sink—a process called hydraulic buoyancy. Its stubby wings translate some of that up-and-down motion into a forward speed of about a mile (1.6 km) an hour in a sawtooth pattern. As it regularly approaches the surface, an air bladder in the tail inflates to stick an antenna out of the water so it can transmit what it has learned to whatever Captain Nemo dispatched it to the depths…
[continues at TIME Swampland]