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Navy Dives Deeper Into Mine Countermeasures

July 2001
By Maryann Lawlor
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Tomorrow’s sensor technologies take aim at a tenacious threat.

Autonomous underwater vehicles, unmanned aircraft and miniature tracked vehicles all rigged with enhanced mine-detecting capabilities will assess a dangerous area before troops disembark from ships, providing them with information about what lies beneath. Outfitting battle groups with these relatively small yet powerful technologies will allow them to conduct mine countermeasures independently so that amphibious units can proceed quickly with their missions.

Because mines are comparatively low-technology and low-cost weapons, they continue to be used to prohibit beachfront landings.  Mine countermeasure experts call them the asymmetrical, asynchronous method of warfare. With a few million dollars of equipment, adversaries can deny access to a few billion dollars worth of military power, they explain. Advances in sensor and communications technologies will help diffuse this threat, which has hindered troop movement for decades.

At KERNEL BLITZ 2001, a large-scale biennial amphibious landing exercise held this spring near Camp Pendleton, California, the U.S. Navy’s 3rd Fleet and the U.S. Marine Corps’ I Marine Expeditionary Force took a closer look at how today’s technology will address these formidable weapons. This represents the first time mine countermeasure technology has been examined during the exercise.

KERNEL BLITZ is designed to enhance sailor and Marine training in the complexities of brigade-sized amphibious assault operations. This year’s exercise involved approximately 25 ships, 75 aircraft, and 15,000 sailors, Marines, soldiers, airmen and Coast Guardsmen. In addition to premiering mine countermeasure (MCM) technology, the 2001 event also was the first KERNEL BLITZ to involve multinational forces. Troops from Canada, Australia and Great Britain also participated in the exercise.

The Navy has been exploring the concept of equipping battle groups with their own MCM for several years. Historically, a separate fleet of specialized ships and helicopters would have to be called in to find and destroy mines. Under the new approach, these systems, which would be organic to Navy battle and amphibious ready groups, would complement existing dedicated, in-theater capabilities or hunt for mines in areas where no forward-deployed MCM specialist forces are present. This organic capability will include surface, submarine and airborne systems with advanced sensors that can detect, classify and in some cases neutralize mines. Because the on-site groups have the equipment onboard, they will be able to conduct the MCM activity then continue with the operation quicker and more safely.

The Office of Naval Research (ONR), Arlington, Virginia, sponsored the advanced MCM technologies examined during KERNEL BLITZ 2001. The systems are being developed to detect, identify and classify mines in shallow and very shallow waters. They exploit recent advances in sensors, especially lasers, sonar and television-like imaging; robotics, which host the sensors and include a variety of autonomous underwater vehicles (AUVs); and networking and signal processing technologies. Teams of government, industry and academic partners developed the MCM systems that reduce the number of humans required to enter the dangerous waters just off shore to clear mines prior to expeditionary operations.

According to Capt. Robert T. Schnoor, USN (Ret.), deputy manager of organic mine countermeasures, ONR, countering mines on a beach, the approach to a beach or in a waterway is a complicated mission, and the various methods employed can interfere with an amphibious mission.

“If we can get some good intelligence about the mines being deployed by an adversary—where they are, when they’ve been placed there—then we have a leg up on finding the mines and taking care of them. The toughest part is the beginning of the job—finding the mines. We need to exploit the technology to find the mines. Then, we need the algorithms for analyzing the information to find out what’s going on. The software that can pick out those mines and obstacles on the beach out of the imagery is what is needed,” Capt. Schnoor explains.

Once the on-site teams can determine where the mines are located, they can begin clandestine clearing work. In addition to using satellite images, the ONR is examining other equipment that can gather intelligence. The AUVs play a major role in this effort. They can be preprogrammed to navigate through an area while using sonar to collect information about the undersea environment. They then return to the launching craft with data about the conditions and objects at the sea bottom. The AUVs can be more effective than human divers, the captain says, because they can move faster, dive deeper and stay on station longer.

The battlespace preparation autonomous underwater vehicle (BPAUV), developed by the ONR and Bluefin Robotics Incorporated, Cambridge, Massachusetts, was among the technologies examined at KERNEL BLITZ. The 10-foot-2-inch by 1-foot-9-inch vehicle features flexible survey systems and can be operated from a ship or boat. A behavior-based control architecture facilitates the ability to specify mission objectives, and users can construct missions by employing the established library of behaviors within the system. Because BPAUV is fully autonomous, communications do not take place between the AUV and the launching craft while the reconnaissance mission is underway.

Capt. Schnoor relates that during tests at KERNEL BLITZ his team was impressed by BPAUV’s ability to stay on station for up to 12 hours. Coming into the event, ONR officials expected the AUV to operate for only 4- to 8-hour missions.

In addition to BPAUV, KERNEL BLITZ participants also tested Cetus II, a hover-capable unmanned underwater vehicle (UUV) developed by Lockheed Martin/Perry Technologies, San José, California. According to Gary Trimble, director, marine automation and robotics engineering at the company, other UUVs and AUVs must continue moving during operations, while Cetus II can hover and thoroughly assess an underwater object. Vehicles that must maintain forward motion work in tandem with the hover-capable craft. The former is sent out to evaluate the environment; the latter returns to areas of interest to gather additional information.

Cetus II, which is about the size of a sea trunk, carries high frequency sonar and low-light video imaging equipment to obtain high-quality images of underwater objects from more than 19 feet away. The sensor data is logged onboard and downloaded when the vehicle is recovered.

KERNEL BLITZ presented a new challenge to testing these types of MCM systems, Capt. Schnoor opines. The equipment has been tested off the coast of Panama City, Florida, where weather and water conditions are relatively clear. In comparison, conditions near Camp Pendleton featured stronger winds and limited visibility on the seabed. Despite these factors, the underwater sonar still did a commendable job of detecting underwater contacts, the captain relates.

Not all MCM systems tested at the exercise look like minisubmarines or operate under the water. The surf zone crawler reconnaissance vehicle, for example, is the size of a large breadbox and resembles a toy remote-control tractor-tread car. Squads of the vehicles can be sent out to scout or map out potential amphibious approach lanes through the surf zone.

Foster-Miller Incorporated, Waltham, Massachusetts, and the Navy’s Coastal Systems Station, Panama City, Florida, are partnering in the surf crawler research. They are developing practical techniques for navigation, communication, sensing and autonomous control.

Each robot carries a suite of close-range sensors to detect mines and obstacles while at the same time reject clutter. The current plan is to release a squad of crawlers to search a predetermined region of the sea bottom. When it finds an object that could be threatening, it would report to a remote human operator and provide an image for identification.

According to Tony Aponick, vice president at Foster-Miller, the crawlers are not preprogrammed. When a group of the vehicles is dropped in a designated location, they would map out the area by simply milling about. One possible tactic would be to release the robots into an area suspected of containing mines, use them to verify the existence of the mines, then detonate the crawlers after a specified amount of time, Aponick explains.

The team is currently addressing two concerns about this strategy. First, the detonation of the crawlers may not destroy all of the mines located in the area. During combat, this result, while not ideal, is an improvement over entering an area without any MCM whatsoever. However, when mines are being cleared from an area to provide safety to residents, this result would be unacceptable. In addition to the less-than-perfect eradication of the mines, the Navy is also concerned about the impact the explosions would have on the environment, Aponick says.

While robots are getting up-close-and-personal with mines in the water, sensors on board aircraft will help troops assess a potentially dangerous situation from above. These technologies currently are being tested on small manned airplanes, which saves money, but the equipment is designed to be installed on unmanned aerial vehicles (UAVs).

The airborne remote optical spotlighting system (AROSS), developed by Areté Associates, Sherman Oaks, California, comprises a digital camera that is mounted in a stabilized turret located on the underside of the aircraft. The camera collects time series data about the surf area. Once the craft is back on the ground, analysts view the information and can determine the location of mines based on how waves break over certain locations.

According to Robert Madson, senior engineer, Areté, currently the data cannot be transmitted in real time. This capability may be available in the future. AROSS has demonstrated that it can perform with the Navy/Marine Corps future vertical takeoff UAVs, Madson says. In addition to mine detection, it could also be used to spot navigational hazards and for littoral zone bathymetry and currents assessment as well as precise tactical targeting, he adds.

The ONR also is investigating technologies that will analyze all of the data that is collected by this equipment. At KERNEL BLITZ, participants examined the Summus Sonar Juggler, a proof-of-concept side-scan sonar image processing software package. The tool set analyzes the Navy’s unified sonar image processing system, or UNISIPS, side-scan sonar images.

Current Juggler modules include a fast segmentation of high-reverberation/high-clutter and featureless/low-reverberation regions, identification of sand ridge areas, detection of cast shadows and their geometric and statistical properties, and identification of pockmark areas.

Capt. Schnoor points out that processing the vast amounts of environmental data has become a problem, so the Navy is investing in technologies that will help analyze it. In addition to the large quantity of information collected during one surveillance mission, the service must address the continuous stream of data that must be collected as the environment changes. This information supports command decisions about where mines may be hidden and how best to search for them, the captain explains.

KERNEL BLITZ participants also examined technologies that will support moving data quickly to where it is needed. “We want to relay the information from underwater to an airborne vehicle and then on to a ship. These technologies worked well during KERNEL BLITZ. The environment is a challenge. In the areas of breaking surfaces, there is a lot of ambient noise because of the surf,” Capt. Schnoor offers.

The next step for MCM systems is to continue improving the various aspects of the technologies. “Is there a better sonar processor that we could put in the vehicle? We are incorporating different sensors on different vehicles, and we will continue to refine the technology and capabilities,” he says.

In the immediate future, the U.S. Naval Special Warfare Command, San Diego, has acquired remote environmental monitoring units, or REMUS, developed by the Oceanographic Systems Lab, Woods Hole Oceanographic Institution in Massachusetts. REMUS vehicles, which are low-cost UUVs, will be replicated and will enter service with the Navy Seals at the beginning of fiscal year 2002, Capt. Schnoor states.