(Corrects weight of mine in 15th paragraph of story published May 10.)
Underwater mines are lurking in critical waterways around the world. Low-tech but highly destructive, they can blow up ships, destroy oil and natural-gas pipelines and wipe out telephone and Internet cables.
By U.S. Navy estimates, about 50 countries stock more than 250,000 maritime mines that could be dropped in the world’s oceans, Bloomberg Businessweek reports in its May 14 issue. China has the most extensive and sophisticated inventory of mines, according to naval analysts. If Iran had shut down the Strait of Hormuz earlier this year, as some of its officials threatened, its strategy probably would have involved deploying its stockpile of mines.
“We have traditionally been under-equipped for the mine- sweeping mission” because U.S. allies picked up that role in the aftermath of World War II, says Andrew Krepinevich, president of the Center for Strategic and Budgetary Assessments in Washington. “Right now the Navy is looking at mine-sweeping because the problem is getting bigger.”
The Navy currently relies on a small fleet of ships and divers dispatched from submarines to find mines and defuse them. Trained dolphins, equipped with cameras and sensors, also sniff them out. With the Pentagon facing as much as $1 trillion in budget cuts over the next decade, finding money for those missions “is going to be a huge challenge,” says Captain Duane Ashton.
Counting on Knifefish
Instead, the Navy plans to rely on the Knifefish, an underwater drone that Ashton’s Unmanned Maritime Systems Program Office is developing. The Knifefish is 19 feet long (5.8 meters), weighs 1,700 pounds (771 kilograms) and is powered by lithium-ion batteries. Shaped like a torpedo, it will roam the deep seas for 16 hours at a time -- unpiloted.
The Navy is spending $170 million over the next five years to design and buy eight of the robots from General Dynamics Corp. (GD:US) and Bluefin Robotics Corp. It says it expects to deploy the first Knifefish in 2016, acquiring 52 by 2034.
The drones are an upgrade from a small fleet of remote- controlled underwater vehicles the Navy has used since the 1990s to comb shallow harbors and clear debris for ships. After these vehicles make out suspect objects, the Navy must send in divers to investigate further.
The more powerful Knifefish sweeps for mines by sending out low-frequency sound signals. When they bounce off a man-made object, the drone develops an image that it takes back to analysts aboard its mother ship.
It “can tell a mine from a refrigerator littering the bottom of the sea,” Ashton says.
The challenge for the Navy lies in programming the drones to operate without a pilot directing them via a cable, which would restrict their reach in deep water.
‘Can’t Just Joy-Stick’
“The ocean is so big that you can’t just joy-stick” drones, says Tom Curtin, a former scientist at the U.S. Office of Naval Research. Sea floors aren’t well-mapped and change constantly due to shifting currents and weather. Unlike their aerial cousins, underwater drones can’t connect with satellites or GPS to navigate when they’re submerged.
Eventually officials hope to build underwater drones 10 times as large as the Knifefish that could blow up mines, says Thomas Swean, team lead for ocean engineering and marine systems at the Office of Naval Research.
First the military has to develop better power sources so the bigger drones “can last three months instead of two days” without needing a recharge, Swean says.
Beyond the Navy, the gas and oil industry deploys drones for pipeline surveys and inspecting ocean rigs. Researchers use them for studying ocean warming and exploring under the Arctic ice cap.
Hydroid Inc., based in Pocasset, Massachusetts, a subsidiary of Kongsberg Maritime AS of Norway, has underwater vehicles from the small, 80-pound Remus 100 used for post-storm inspections of the sea to the deepwater Remus 6000 that was deployed to find debris from Air France Flight 447, which crashed off the coast of Brazil in June 2009.
Lockheed Martin Corp. (LMT:US) is promoting its 10-foot-long Marlin underwater robot to inspect oil rigs and undersea pipelines in the Gulf of Mexico, replacing towed vehicles that do the job now. Boeing has been touting its Echo Ranger unmanned submarine for similar missions.
The market for underwater unmanned vehicles may grow about 80 percent to 2,400 worldwide by 2016, says Steven Kopits, managing director in the New York office of Douglas-Westwood LLC, a marine market researcher based in Canterbury, U.K. The robots are priced from $50,000 for small ones used in shallow water to $1 million for a fully autonomous deepwater vehicle.
Underwater vehicles can roam the seas with more autonomy than aerial drones, says Gary Roughead, a former chief of Naval Operations who is now a fellow at the Hoover Institution at Stanford University in California.
“As much as people have been taken with unmanned aerial vehicles, you haven’t seen anything yet,” Roughead says.
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