Navy Drones Take to the Sea

The Navy is seeking 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. But in a new twist, the Navy has found a way to power an eventual fleet of 150 submersible drones from the ocean itself, increasing deployment times and cutting fuel costs.

The drone, known as the Slocum Glider, changes density in response to the outside water, causing the 5-ft.-long (1.5 m) torpedo-like vessel to rise or sink through the ocean’s thermoclines, or bands of warm and cool water at and below its surface. The stubby wings translate some of that up-and-down motion into a forward sawtooth-like path at about a mile an hour (1.6 km/h).

Much of the work such gliders do is oceanographic, collecting data about water temperature and currents. The drone transmits such information–used to generate better sonar images–to headquarters by sticking its tail-borne antenna out of the water. But the drones are also being enlisted to scout enemy coastlines, where they could help the Navy hunt down minefields and target subs without putting sailors at risk.

–MARK THOMPSON