The U.S. Navy is developing a new mine-detecting Unmanned Surface Vehicle (USV) engineered to sweep across the ocean in search of mines using magnetic and acoustic technologies, service officials said.
“We have an Unmanned Influence Sweep System (UISS) which consists of a boat with no people on it with a magnetic and acoustic device that it tows, called the Unmanned Surface Sweep System (US3). Together, this will allow us to replace the MH-53 helicopters that we use today in the legacy fleet to do these kinds of mine sweeps,” said Capt. John Ailes, Mission Modules program manager, Littoral Combat Ship (LCS).
The Navy plans to award a contract to up to two industry teams to build the new boat next year, following the release of a draft Request for Proposal to industry in December 2012, said Navy spokesman Matt Leonard.
The effort, which began with the Office of Naval Research, is now part of the Navy’s current testing and development of a series of integrated next-generation counter-mine technologies for its Littoral Combat Ship (LCS), a near-shore multi-mission platform engineered to bring a wide range of counter-mine, surface warfare and anti-submarine capabilities to the fleet, service officials said.
The technologies are part of the LCS’ Mine Counter-Measures (MCM) Mission Package, a combination of sensors, vehicles, weapons systems, modules, aircraft and crew members integrated to bring a new combination of mine-detection and neutralization systems to the fleet.
The service plans to conduct fabrication and formal testing of two Low Rate Initial Production units from 2015 to 2017, to be followed by Initial Operational Capability in 2017, he added.
Overall, the MCM Mission Package incorporates a host of technologies engineered to be implemented in specific “increments” depending upon their developmental timetable; the first increment, now being tested in waters off San Diego on board the USS Independence, an LCS variant, combines airborne and underwater mine-detection sensor capabilities.
For instance, Increment 1 incorporates the MH-60 S Sea Hawk helicopter’s Airborne Laser Mine Detection System (ALMDS), a high-tech sensor engineered to use laser technology to scan the water for mine threats at the shallow end of the water column.
“This is the first time the Navy has used lasers searching through the top of the water column to find mines,” Ailes explained. “For the rest of the water column we use a sonar technology.”
The MH-60S also utilizes an Airborne Mine Neutralization System, currently in Low Rate Initial Production, Ailes added.
“The mine neutralization system consists of a carriage. The carriage lowers down and it has neutralizers on it. It uses a fiber optic cable so that when you send the neutralizer out you can drive it into the target. The helicopter operator has both an optical display as well as a sonar display,” he added.
When in proximity to a mine, the Airborne Mine Neutralization System uses a camera with onboard halogen illumination to allow for positive identification prior to detonation; the system uses self-propelled explosive neutralizers to destroy mines, Navy officials explained.
The sonar display comes from another element of the MCM Mission Package called the Remote Multi-Mission Vehicle (RMMV), a diesel-powered semi-submersible with a snorkel tube and communications mast, Ailes explained.
The RMMV is equipped with an AQS-20A mine-hunting sonar device engineered to send and receive sound-wave “pings” through the ocean, analyzing the return signal, Ailes said.
“This allows us to take the ships out of the mine field. The sonar can be lowered depending upon what depth you are searching,” Ailes explained. “Today when you want to go into a mine field, you take a wooden ship in there with people on there. Now, we can send these unmanned systems into the mine field.”
In fact, the RMMV system recently finished up what the Navy calls a reliability growth plan designed to identify and address every potential failure mechanism. “We can now go many hours without an operation mission failure,” Ailes explained.
Sonar technology can help identify the shape, size and distance of a potential threat object by analyzing acoustic signals in relation to the time it takes them to travel, Ailes explained. Since the speed of sound is a known value, the distance a sound wave travels can be determined through an algorithm, providing the location of an object such as a mine.
“Ping by ping you can see things. You put the acoustic energy in and it comes back and you see a response in time and in amplitude --proportional to target strength or a measure of the cross-sectional energy. Different objects have different responses. We teach the operators what a mine looks like and it takes some training,” Ailes added.
At the same time, the Navy is currently in the process of upgrading the sonar technology used on the LCS’ MCM Mission Package to a higher-resolution “synthetic aperture sonar” currently used on submarines, Ailes explained.
This will enable sonar operators to more quickly and easily make determinations regarding what is a mine – and what is not.
“With higher resolution you can more easily tell the shape. As we introduce this incrementally, it will become easier on the operator. What that means is a lower false alarm rate and also less training to get to that same level of proficiency,” he said.
The Navy is also developing a low-frequency broadband sonar, called Knifefish, able to detect clusters of mines buried beneath the ocean floor using synthetic aperture sonar, Ailes added.
“This sonar has the properties which can find things even if they are buried. It measures the density of the signal coming back,” he said.
Knifefish is a 19-foot long, 1,700-pound Unmanned Underwater Vehicle (UUV), a propeller driven mine-sweeping robot made by General Dynamics Advanced Information Systems and Bluefin Robotics.
Formal testing and Low Rate Initial Production of four Knifefish systems will take place from 2014 to 2017, culminating in Initial Operational Capability delivered to the LCS MCM Mission Package in 2017, Leonard explained.
Knifefish, which is able to search for and map mines, emerged from research conducted by the Naval Research Laboratory, Leonard added.
At the same time, Electro-Optical sensors, some of which can be configured onto the end of the AQS-20A are also often used to positively identify mines.
The airborne mine-detection systems are designed to work in tandem with the sonar so that the upper and lower portions of the “water column” are sufficiently swept for mines in an integrated fashion, Ailes said.
The second increment of the MCM Mission Package includes the use of the Fire Scout Vertical Take-off-and-Landing Unmanned Aircraft Systems (UAS); the Fire Scout is engineered with a special, high-resolution mine-detecting sensor able to determine if mines are buried underneath beach sand along the coastline, called Coastal Battlefield Reconnaissance and Analysis (COBRA), Ailes added.