Navy unleashes drone swarms and laser tech against sophisticated sea mines, safeguarding crucial waterways from rising threats.
By Kris Osborn, Warrior
Helicopter-mounted lasers, undersea drones and high-speed surface vessels equipped with advanced sonar are all current mine countermeasure methods now deployed by the U.S. military, yet many are likely to wonder how they might perform against Iranian mines in the current conflict.
Undersea mines have been a threat in the Strait of Hormuz for many years, yet the current war with Iran has thrust the concern to the forefront of Pentagon consciousness, as senior defense and Trump administration leaders deliberate potential courses of action. Will the U.S. send a Navy-Marine Corps combined force to secure the Strait? How might the U.S. Navy counter drone swarms, small boats and Iranian sea mines?
Mines can be tethered to the ocean floor to explode on impact, linger just beneath the surface, buried beneath the bottom of the ocean and set to detonate by undersea soundwaves. Mines are as ubiquitous as they are dangerous, and often cheap for adversaries to acquire, yet they are also increasingly sophisticated and proliferating at a concerning rate.While mines can of course cause casualties, destroy ships and present real “kinetic” threats, they are also used to simply “deny” access to a sensitive area or make the price of entry simply too high for manned vessels to operate.
Drone Boats & Sonar
It may seem almost too obvious to mention the growing importance of drones, sensors and unmanned boats when it comes to finding and exploding or neutralizing enemy mines. In recent years, the US Navy has been fast-tracking a growing suite of AI-enabled, high-tech multi-domain mine countermeasures to include laser sensors scanning the top portions of the water column, small semi-autonomous mine-hunting drones such as Raytheon’s Barracuda or side-scanning AQS-20 towed synthetic aperture sonar lowered beneath highly maneuverable groups of unmanned boats sending data to a manned host ship.
Naval Sea Systems Command has also for years been working with industry to develop, assess and analyze mine-neutralization technologies for its high-speed drone boat called the Mine Countermeasures Unmanned Surface Vehicle (MCM USV) -- a multi-mission surface drone countermine platform designed to hunt and destroy mines autonomously using sonar. As a result, the current exploration of mine-neutralization technology is happening alongside the ongoing integration of advanced sonar mine-hunting payloads onto the USV -- the AQS-20 and AQS-24.
Mine-Hunting Drones
When networked together, manned boats performing command and control can observe and benefit from a semi-autonomous mine detection and destruction progress wherein a lowered sonar system such as the AN/AQS-20C can work in tandem with the Barracuda to find, identify and wirelessly detonate otherwise touch to counter mine threats.The AQS-20 is a submersible cylinder-like system with four built-in sonars to find mines from the “sea-floor to the near surface in a single pass,” Raytheon data explains. It operates with side-scanning synthetic aperture sonars, a “wide-band” forward-looking sonar and a “digital gap” filler sonar to surveil mines underneath. Using acoustic ID technology, the AQS-20 generates a high-resolution “rendering” or “image” of a threat object using advanced automatic target recognition.
As communications and networking technologies continue to evolve rapidly, drones will increasingly be able to function in a cross-domain capacity, meaning across air, sea, land and undersea operations. A human at a control station, using a low bandwidth connection, can perform command and control functions without needing to actually drive the vessels. Algorithms governing autonomous maritime navigation have progressed to the point where USVs can more effectively “perceive” and respond to their surrounding environment while in transit. Small, high-tech autonomy kits can be integrated onto unmanned surface vessels. The kits, called Control Architecture for Robotic Agent Command and Sensing, or CARACaS, are engineered to provide USVs with an ability to handle dynamic operational situations; this can include the execution of search patterns, harbor defenses, surveillance or even swarm boat attacks.
Laser Mine Detection
The US Navy can also deploy a MH-60S helicopter-mounted laser system to scan and detect underwater mines. The now-operational technology, called Airborne Laser Mine Detection System (ALMDS), enables efficient, high-speed shallow water mine detection for the Navy’s Littoral Combat Ship or other helicopter-launching service vessels such as amphibious assault ships. Instead of using more narrowly configured, mechanized or towed mine detection systems, ALMDS massively expands the surface area from which mine detection takes place. Naturally, this enables shallow-water warships such as the LCS to have a much safer sphere of operations as commanders will have much greater advanced warning of mine-cluttered areas.
The ALMDS pod is mechanically attached to the MH-60S with a standard Bomb Rack Unit 14 mount and electrically via a primary and auxiliary umbilical cable to the operator console, according to a statement from the systems maker, Northrop Grumman. Northrop Grumman weapons developers explain that the system does not use bombs, but rather flies at a specific altitude and speed to emit laser beams at a certain rate. Cameras underneath the helicopter receive reflections back from the water which are then processed to create images.
The camera or receiver on the helicopter is called a Streak Tube Imaging LIDAR (STIL). The laser is released in a fan pattern, and photons received back are transferred into electrons, creating a camera-like image rendering.Northrop information on ALMDS further specifies that the system can operate in both day and night operations without stopping or towing equipment in the water. ALMDS could provide occasion for the ship to alert other surface and undersea vessels about the location of enemy mines. In fact, Northrop writes that ALMDS provides accurate target geo-location to support follow-on neutralization of the detected mines.
Counter-Mine Laser Research
Some of the technical details of the ALMDS system are further delineated in a research paper written by Arete Associates – a science and technology consulting firm with a history of supporting entities such as the Office of Naval Research and the Air Force.
“A high resolution 3-D image of the scene is produced from multiple sequential frames formed by repetitively pulsing the laser in synchrony with the CCD (Charge Coupled Device) frame rate as an airborne platform "push broom" scans or as a single-axis scanner on a ground-based platform scans the laser fan beam over the scene,” the Arete Associates essay titled “Streak Tube Imaging LIDAR For 3-D Imaging of Terrestrial Targets, writes. “The backscattered light from the objects and the terrain intersecting the fan beam is imaged by a lens.”
STIL technology, while only recently becoming operational with ALMDS, has been in development as a maritime surveillance system for many years. A 2003 study from the Naval Surface Warfare Center cites how “pulsed light” sent out from a three-dimensional electro-optic sensor STIL system can “identify objects of interest on the ocean bottom.” The Arete essay also talks about STIL technology also being developed and tested for use as a “missile seeker” by weapons and a sensor system for an Air Force C-130 aircraft.