Drones have become an essential platform for any military and they have changed the shape of recent conflicts. Their slow speed and small radar cross-section have created a lot of challenges for conventional sensors and weapons to detect and engage them. Many technologies have been developed for their detection and neutralization vast range of platforms, from small, homemade devices to large, sophisticated uncrewed aerial vehicle (UAV) platforms.
New actors are quickly emerging including autonomous uncrewed underwater vehicles (UUVs), which bring an entirely new challenge to your subsea defence operations. Unmanned underwater vehicles (UUV) are any vehicles that are able to operate underwater without a human occupant. Smaller and cheaper autonomous underwater vehicles (AUV) are today very capable and gaining users. Large autonomous underwater vehicles are more expensive but they offer capabilities in some missions and applications that no other platforms can offer.
Within the last decade, interest in UUV to be part of specific military, industrial and academic missions and applications have increased due to technological innovation and the evolution of their sensor payload. Missions such as persistent surveillance, anti-submarine warfare, oceanography and mine coutermeasure are amongst those where UUV capabilities far exceed those offered by other platforms.
Uncrewed platforms in the underwater domain present an entirely new set of challenges for friendly forces. UUVs are ideal for information gathering. They may collect intelligence information through ISR missions including intelligence collection of all types (imagery, acoustic, water profiling), target detection and localization, and mapping (e.g. Intelligence Preparation of the Battlespace (IPB) and Oceanography). UUVs are uniquely suited for information collection due to their ability to operate at long standoff distances, operate in shallow water areas, operate autonomously, and provide a level of clandestine capability not available with other systems.
In an operational context, a UUV is launched from a platform of opportunity, submarine, surface ship, or even an aircraft or shore facility and then proceeds to the designated observation area. It then performs its mission, collecting information over a predetermined period of time. It autonomously repositions itself as necessary, both to collect additional information and to avoid threats. The information collected is either transmitted back to a relay station on demand or when self cued (i.e., when the vehicle records a threat change and determines that transmission is necessary)
The environment is almost the perfect blend of protection measures for potential foes where they benefit from cover from subsea terrain and noise, as well as naturally occurring fauna, animals and debris. In busy ports and harbours, vessels and crews are under substantial danger, with traditional detection systems like cameras and radars offering very little visibility underwater if at all. This makes the reliable detection of underwater intruders of any form a notoriously tricky problem, but in the case of subsea drones that are small and extremely quiet, it can seem almost impossible.
Confined spaces in ports and harbours are notoriously difficult, noisy acoustic environments. The vessels themselves are sources of noise as they come and go. In addition, shallow waters create a complex thermal structure affecting the sound velocity profile that in turn limits the performance of your acoustic systems.
Fortunately, acoustic sonar systems can be deployed to stand up to them. Only by making the right design choices, it is possible to detect hostiles using sonar. Once a target is detected, it must also be classified and distinguished from marine fauna, otherwise potential foes could be missed, or crews sent to investigate harmless objects in dangerous environments. Telling apart a harbour seal from a terrorist diver or UUV is a determination that must be made correctly, or the consequences could be dire.
Just as UAVs went from ISR to offensive roles, UUVs will also take an offensive role in underwater conflicts. UUV technologies have been evolving from defensive to more offensive roles. UUVs increasingly play a critical role in antisubmarine warfare (ASW) and perform missions such as placing and monitoring sensors on the sea floor to track enemy submarines. They can gather intelligence on opponents, detect and neutralise mines, hunt submarines and chart the ocean floor. They could, potentially, detonate warheads. And they could take part in a coordinated attack on an enemy submarine in conjunction with ‘friendly’ submarines and surface vessels.
Swarms of autonomous underwater drones could be deployed to hunt ballistic-missile submarines, targeting a cornerstone of nuclear deterrence. Groups of networked unmanned vehicles swim around independently, carrying out high-level processing and sharing information between other members of the submerged fleet, ultimately carrying out detection and classification of enemy assets including submarines and passing the information to a command and control centre, or carrying out their own prosecution, is threatening.
Several reports indicate that Russia has been working on a ‘killer underwater drone’ since 2015. The ‘Cephalopod’ is designed for the underwater battlefield. Undersea warfare expert H.I. Sutton says that it can target shipping but its torpedoes are intended to destroy submarines.
A RAND Corporation report, Emerging trends in China’s development of unmanned systems, said Beijing had been funding 15 different universities for research programs for UUVs. Reports indicate that China is also developing low-cost unmanned UUVs for a variety of military applications, including ‘suicide’ attacks on enemy vessels.
Experts have pointed to future role in laying mines on the battlefield. To lay a minefield a UUV would have to be much larger, large enough to carry a useful number of mines. U.S. is the first sea power to start building extra-large unmanned underwater vehicles (XLUUVs). But other navies are also entering the arena, including Britain and Japan. And China, Russia, and South Korea also have large UUV projects.
The U.S. Navy’s Boeing Orca underwater drone could play an offensive role in future conflicts. The Orca design will be even larger and therefore could patrol further and could carry more. The Orca is up to 85 feet long, an order of magnitude larger than anything else out there as the moment. It has a flexible payload section which is large enough to carry multiple torpedo sized payloads.
Emerging technologies like unmanned underwater vehicles (UUVs) add to the complexity of the battle space and disrupt the status quo. Emerging capabilities suggest that the sea-based leg of the triad of missile submarines, land-based intercontinental ballistic missiles and crewed bombers will increasingly become vulnerable.
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