A new epoch––autonomous underwater vehicles (AUVs)––promises a radical change in undersea warfare at just the time when conventional technology is becoming less and less affordable throughout the naval world.
The greatest threat to warships and commercial shipping is not anti-ship missiles or torpedoes, but rather mines.
Potential adversary navies have on the order of 386,000 naval mines––China 80,000; Iran 6,000; North Korea 50,000; and Russia 250,000––facilitating anti-access/area-denial (A2/AD) strategies, while U.S. Navy assessments indicate that a million mines are in the inventories of more than 50 navies world wide.
The nub of the problem is keeping up with the global threat, which today includes weapons of some 300 different types, from rudimentary but still-dangerous World War I-era contact mines to highly sophisticated, multiple-influence, programmable weapons, many available on the open market.
Insurgents throughout the Middle East have been attacking Western forces with improvised land mines––IEDs––and surely the naval equivalent is coming. Indeed, underwater IEDs can be fashioned from 50-gallon drums, and even discarded refrigerators. Defeating the terrorist UWIED threat was the focus of the April 2016 International MCM Exercise in the Persian Gulf, which brought together 30 countries’ MCM and explosive ordnance disposal (EOD) forces.
And minelaying is unfortunately relatively easy.
In 1984, Libya mined the Red Sea, with as many as 19 commercial vessels damaged by mines. In 1991, in preparation for operations in the Arabian Gulf, the U.S. Navy tried to monitor Iraqi minelaying. The Navy knew that its mine clearance force was limited, so it hoped to avoid areas that had been mined. The Iraqis had specialized minelayers, which were monitored, but they were not sufficient, so the Iraqis also used all sorts of small boats, which proved difficult to monitor. The two U.S. ships that were mined in the Gulf, the helicopter carrier Tripoli––ironically, the mine countermeasures (MCM) flagship––and the guided missile cruiser Princeton, were in areas believed not to have been mined at all.
The problem navies face is that mines and mine-like objects have to be detected, examined and, if a mine, neutralized one by one before a harbor, waterway or naval operating area can be declared safe.
Not only is such examination tedious, but also it is dangerous and requires considerable specialized technology.
How long would a report (which might be false) that a merchant ship had dropped a string of mines in, say, Rotterdam or Los Angeles/Long Beach, close that port?
Given the shrinking number of super-ports in the world, what would be the impact of closure for, say, a month or two?
Once the port reopened, how confident would anyone be of its safety?
It takes human intelligence to decide whether an object on the bottom of the sea, which might be covered in marine growth, is a mine or junk or something natural.
The world’s minehunting ships deploy underwater robots that use sonars and underwater cameras to examine objects on the seabed detected by short-range sonars on board the ships.
Even the robots often cannot come very close to the objects, which might be triggered by their presence.
Once the humans on board the minehunting ship decide that an object seen by the robot is a mine, the robot is withdrawn, a charge is laid near the supposed mine, and it is detonated.
The minehunting ship cannot proceed to the next object until the last has been dealt with.
The robot cannot go far from the minehunter because the short-range sonar on board the minehunter guides it and in most cases the robot is tethered to the ship.
Even worse, the charge often neutralizes the mine without visibly destroying it, so that minehunting demands automatic charting of what objects have and have not been detected and neutralized.
None of this would be a great problem if minehunters (and their expert crews) were inexpensive and therefore numerous.
Once virtually every navy had large numbers of minesweepers, after all, the sweepers were more or less expendable. Minehunters are not. They have to be built so that they do not set off the mines they are hunting.
Their mine-recognizing personnel are difficult to train, so there are not many of them.
No navy in the world can afford a large fleet of minehunters, but the technique of mine hunting is slow, on the order of days if not longer depending on the nature of the threat and the marine environment.
It would not take many mines to paralyze a large port or close a strategic strait.
Many minehunters working together could clear such an area quickly––but there is no way that many minehunters of the current type can be fielded by any navy, even the wealthiest.
The Autonomous Solution
AUVs are a proven way out of this problem, which is likely to increase as navies and terrorists alike realize the potential of sea mines.
They are already well aware that the lifeblood of the regimes they hate is the oil moving on tankers. The Iraqis and Iranians certainly understood as much during their “tanker war” in the 1980s, as did Libya in the 1984 mining of the Red Sea. Mines were a horrific problem.
The “A” in AUV means that the device operates essentially on its own and carries sensors and data recorders. It is so small that it is most unlikely to set off a mine, and it can range far ahead of the ship employing it.
The ship does not assign the AUV to examine a target of interest it has detected.
151117-N-AC237-239 VIRGINIA BEACH, Va. (Nov. 17, 2015) Sailors from Mobile Diving and Salvage Unit (MDSU) TWO launch the MK 18 underwater unmanned vehicle (UUV) during a training evolution at Joint Expeditionary Base Little Creek-Fort Story. The training helps provide MDSU TWO Sailors with famililiarization of the MK 18 UUV for future missions. (U.S. Navy photo by Mass Communication Specialist 2nd Class Benjamin Wooddy/Released)
MK 18 Mod2
VIRGINIA BEACH, Va. (Nov. 17, 2015) Sailors from Mobile Diving and Salvage Unit (MDSU) TWO launch the MK 18 underwater unmanned vehicle (UUV) during a training evolution at Joint Expeditionary Base Little Creek-Fort Story. The training helps provide MDSU TWO Sailors with famililiarization of the MK 18 UUV for future missions. (U.S. Navy photo by Mass Communication Specialist 2nd Class Benjamin Wooddy/Released)
Instead, it orders the AUV to search an area, which can be far from the ship. It may have sufficient intelligence to classify objects, filtering out the mass of objects on the seabed and simplifying the task of the humans who must ultimately decide whether an object is worth attacking.
AUVs can now navigate well enough that they can effectively report where these objects are.
Once the human on board the controlling ship decides that a particular target of interest, some other device can be vectored to attack it.
Unlike an unmanned aircraft, it cannot easily communicate continuously back to a controller, because underwater communication is limited (and in a coastal area it may also be limited by underwater terrain).
When it encounters obstacles, for example, the AUV must decide what to do (that has been an obstacle to rapid AUV development). The AUV must incorporate sufficient intelligence that it need not be embedded in a complex shipboard combat system. All it needs is a mission-planning system, which can reside on a laptop computer, and initial alignment of its navigational system. The memory that contains the commands also contains whatever data the AUV collects.
Typically the data gathered during the mission is downloaded once the AUV is recovered.
As an alternative, the AUV can transmit back what is on board as part of the mission and continue searching.
Because the AUV, and not the control ship, goes into the minefield, there is no need to build a special low-signature (i.e., brutally expensive) ship; any ship that can deploy an AUV will do and, in practice, has done. Importantly, the ship does not have to proceed through a potential danger area step by step. It can launch several AUVs, and they can explore different parts of the area at the same time.
It is as though there were many minehunters, working in parallel, each working much faster than in the past. This is the thinking behind the MCM mission modules embarked on the U.S. Navy’s littoral combat ships.
Fast and relatively inexpensive clearance operations can have enormous tactical and strategic consequences.
Leading the Revolution
The AUV revolution is being led by Hydroid, a U.S. company now owned by Kongsberg of Norway.
The Office of Naval Research began the program with the Woods Hole Oceanographic Institution in 1991 with at-sea tests using the REMUS 100 (the number indicating maximum depth in meters) carried out in 1993. (Hydroid was spun off from Woods Hole in 2001 and began developing and producing REMUS AUVs. Kongsberg acquired Hydroid in 2008.)
It entered combat in the Middle East in 2003 as REMUS 100 (a 7.5-inch diameter man-portable AUV the U.S. Navy now calls the MK18 Mod 1). This was the first AUV to be proven in combat and in mid-2016 was being used by 19 navies, with more than 250 systems fielded.
The U.S. Navy adopted the AUV because its experience in the 1991 Gulf War (Desert Storm) demonstrated that conventional minehunting could not possibly clear areas rapidly enough. Very shallow water was an even more difficult proposition, typically requiring divers.
The U.S. Navy and the Marine Corps formed a Very Shallow Water Mine Countermeasures detachment (Naval Special Clearance Team 1) consisting of SEALs, EOD personnel, and Marines. They bought MK18 Mod 1s. Typically they were launched by hand from RHIBs (rigid hull inflatable boats) with minimal adaptation. The 80 lb Mod 1 offers 6- to 8-hour endurance and a maximum depth of 100m, so it proved useful for inshore work.
The operations in Iraq showed what AUVs could do, and they revealed a need for a longer-range version, which used off-the-shelf components. This larger Mod 2 (REMUS 600) has the same 12.75-inch diameter of a lightweight torpedo but greater length and hence greater weight (800 lbs), has an endurance of 20 to 24 hours, and can dive to 600m. The greater size of this AUV was dictated by its larger lithium-ion battery, which offers 11-17 Kw-hours, compared to 1 KwH for Mod 1.
This version inspired a 2011 U.S. Fifth Fleet JUONS (Joint Urgent Operational Need Statement) for this capability to augment its existing, aging MCM Force.
The MK18 systems were proven as highly successful with greater than 98% availability, low maintenance and easy operation. As a result the Navy opted to return four of the Avenger Class MCM ships to the United States, replaced by a very small but effective team of AUVs, 11-meter RHIBs and their operators. In the two years since the first MK18 Mod 2s arrived in Bahrain they have carried out more than 900 missions.
Based on this experience, the U.S. Navy created an Expeditionary MCM Company (about 25 personnel, a mix of hydrographers and EOD divers) equipped with multiple MK18 Mod 1 and one Mod 2 AUVs.
Real-world performance has been so good that in November 2015 the Navy asked for additional MK 18s to be delivered by September 2017, at a cost of about $8.7 million.
Several other navies are now using REMUS 600s to equal effect. In all, more than 90 REMUS 600 models have been delivered as of mid-2016.
Like Mod 1, Mod 2 can be deployed from an adapted 11-meter RHIB. A surface ship using a variety of launchers and recovery devices can also deploy it. One such device (“Stinger”) can fit into a standard MilVan, and thus can be emplaced on board many ships not normally used for mine countermeasures.
The RHIB and its hardware can be transported anywhere on board a cargo aircraft, such as a C-130. That is far better mobility than a slow minehunter, which can deploy over long distances only on board a heavy-lift merchant ship.
Moreover, the RHIB and the AUVs need far less port support than a minehunter, and they absorb far fewer personnel. They reduce minehunting to the really crucial personnel, the ones who examine sonar images to decide whether an object on the bottom is or is not a target of interest.
All of these AUVs are modular, accommodating various alternative sonars such as forward-looking sonars, small synthetic aperture sonars, and side-scan sonars, and also low-light-level cameras (and underwater lights).
Many of these AUVs are carried by minehunters and deployed using their cranes. However, the important point is that they can be deployed far more flexibly. The minehunters already cost far too much and their numbers are accordingly shrinking in every navy.
Many navies have used larger ships such as survey ships as minehunter mother ships in major clearance operations, placing key command and control systems on board the unspecialized ship.
Now the AUVs make it possible to eliminate the minehunting ships completely, the mother ship handling multiple AUVs to cover areas much more quickly (not to mention, far more safely and covertly).
During the 2016 multi-national RIMPAC (Rim of the Pacific) exercise, the Navy deployed MK18 Mod 2 Kingfish AUVs on board the littoral combat ship (LCS) USS Freedom. The Royal Canadian Navy deployed the Norwegian Hugin 1000 (operated by a Norwegian crew) aboard HMCS Sasketoon and Yellowknife.
The dock landing ship Pearl Harbor was used as a staging base for coalition divers, unmanned vehicles, and marine mammals. Unmanned vehicle teams from Australia, Japan, and Germany were on board. The mine countermeasures part of RIMPAC, conducted off Southern California, involved 77 missions by autonomous unmanned vehicles (mainly Swordfish, Kingfish, and Hugin).
The previous RIMPAC 2014 had employed MK18s; this one used AUVs on a larger scale. This RIMPAC was the first to employ the LCS to operate an expeditionary AUV system, and it was also the first time the dock landing ship functioned as a base.
“This was the LCS’s first major exercise with the MK18s,” an industry official noted. “We tracked 77 successful Kingfish sorties and experienced no issues.”
The LCS operation was particularly significant. LCS was conceived as a modular ship, but that generally meant developing mission modules that had to be integrated into the ship’s combat system. In this case the expeditionary mine countermeasures detachment and its AUVs simply came on board. No integration was needed; the LCS happened to be a platform of convenience.
The stand-alone mission system easily launched and operated the AUV. A stand-alone computer displayed and compared data from a series of missions to enable human operators on the ship to decide whether an object was a mine. Mine-like objects were investigated further by clearance divers. The operators, moreover, were able to maneuver their AUVs around the crowded ships and piers of a harbor.
The Revolution Continues
The success of surface-deployed AUVs has inspired the U.S. submarine force to conceive an underwater constellation of linked AUVs and fixed devices on the sea floor. AUVs turn a submarine from an extremely capable platform operating on its own into a mother ship for multiple unmanned vehicles that enormously expand its effective footprint.
As in minehunting, they capitalize on a few extremely capable and valuable humans by giving them the maximum automated capacity.
That is the revolution––using automation where we can and saving people for the creative jobs, the jobs involving judgment that only humans can do. Nothing can change the sheer vastness of the sea, even of a littoral area.
It seems that only AUVs can make up for the rising cost of the people and the ships we deploy.
|Author:||Dr. Norman Friedman and Dr. Scott C. Truver|