It’s been the Navy’s dream for years: undersea drones that can swim entire oceans. But it’s been thwarted by science’s inability to build propulsion and fuel systems for a journey of that length. Still, the Navy’s top officer and its mad scientists think that some recent research could help turn the dream into an ocean-crossing reality.
“I’m very much desirous of that end-state, cross-ocean, as feasible,” Adm. Jonathan Greenert, the chief of naval operations, told reporters on Friday. “There are a few propulsion systems that can give you that range — 30-day, 45-day. The fuel needed, regrettably, is extensive, and that drives the size, so we’re not there yet.”
What might get the Navy there: academic projects that have propelled robo-subs thousands of miles, and foreign oceanographic research into the briny deep.
Why would you want a robot sub when you’ve got, say, stealthy manned subs like the U.S.S. Jimmy Carter? Because the robots can help the manned subs. If the Carter, say, can deploy a fleet of robotic scouts that can fan out across the oceans and relay aquatic information back to the mothership, it’ll give the Navy a huge advantage over its rivals. And that’s on top of the drone subs’ potential for hunting mines or distracting torpedoes without putting a submariner in jeopardy. Or even, someday, shooting torpedoes of their own.
For now, though, that’s a long way off. The Navy’s current fleet of undersea drones resemble torpedoes in their design, and they’ve got similar ranges and sensing capabilities — that is, not much. Drone subs are in their Ford Model T phase. In 2010, Greenert’s predecessor, Adm. Gary Roughead, all but begged the contractors, engineers and robotics experts at the Navy’s science and technology conference to build him the undersea drone equivalent of a Camaro.
So far, not so much. But there’s a new wave of research that might expand the range of drone subs. The mad scientists at the Office of Naval Research point to Rutgers University (full disclosure: my alma mater), which a few years ago sent its yellow drone “glider,” the Scarlet Knight (yes, it’s yellow for some reason), over 4600 miles of Atlantic Ocean, a trip that took 221 days. The Knight, partially funded by the Navy, is electric powered, though, and so it needs to recharge — a dicey proposition in the briny deep. And it doesn’t descend to the depths of the ocean.
A robo-sub called URASHIMA does. In 2005, the drone, built by the Japanese oceanographic research agency JAMSTEC set a world record for unmanned aquatic exploration by diving to the seafloor and traveling across it for nearly 200 miles. That’s nowhere near as far as Greenert wants, but the oceanographic research drone’s sensors and on-board computer create programmable destinations and adjust to sea conditions, which are crucial for long-range exploration.
Greenert pointed to a few others. “Penn State’s got some good ideas. Johns Hopkins comes through with some ideas. I’m going to go out and mine that again,” he said. (Johns Hopkins is reportedly developing a new drone for deep-sea exploration, building on a decade of undersea engineering.) Among Greenert’s concerns: keeping fuel requirements down so that the drone sub doesn’t become a bloated, stealthless, slow husk weighted down by its energy supply.
For the near term, the Navy’s going to experiment with unmanned subs that can’t swim as far. The Office of Naval Research is developing its own glider, the Persistent Littoral Undersea Surveillance system, or PLUS. It’s a diesel-electric robot for “shallow water” environments that tops out at about 620 miles.
Lessons from PLUS and the other experimental drones will get the Navy thinking about how to crack the ocean-spanning robo-sub problem. “That will be key in the undersea domain,” Greenert said, “to remain our edge.”
External link: http://www.wired.com/dangerroom/2012/03/ocean-drones/