Subsea Combat Mission Sets Converging and Expanding
Recent advancements in undersea systems illustrate the ongoing convergence of sea mines, autonomous underwater vehicles (AUVs), and torpedoes, as well as the emergence of seabed strike as a distinct mission set.
Anduril Industries recently unveiled the Copperhead family of "high-speed underwater munitions," underscoring how advancements in subsea communication, propulsion, navigation, and autonomy continue to drive the transition to multi-mission uncrewed underwater combat vehicles.
- The Copperhead comes in two variants - a 21-inch diameter vehicle, analogous to the U.S. Navy's Mk-48 heavyweight torpedo, and the Copperhead-M, a 12.75 inch diameter vehicle, analogous to the U.S. Navy's Mk-54 lightweight anti-submarine warfare (ASW) torpedo.
- The vehicle is reportedly capable of a 30-knot sprint speed, however its power source, endurance, and range are undisclosed.
- While company promotional materials show vehicles with conventional propellers, the display models at this year's Sea-Air-Space exposition featured toroidal propellers, which would provide greater efficiency and stealth.
- Depending on the vehicle's endurance, multiple Copperheads could conceivably be deployed from a fleet of extra-large AUVs, such as the Dive-XL - the basis for the Royal Australian Navy's Ghost Shark XL-AUV - to engage undersea targets, seed a mobile, wide-area, swarming minefield within the water column, or deploy to the seabed to attack infrastructure or await future activation via acoustic signal.
Other systems currently under development suggest a broader trend toward multi-role underwater strike platforms capable not only of traditional intelligence, surveillance, and reconnaissance (ISR) missions, but also kinetic seabed engagement.
▶︎ Leidos recently unveiled Sea Dart, a low-cost family of small AUVs which, in addition to performing ISR and ASW decoy roles, could be weaponized to attack seabed targets.
- The vehicle has a 19 hour endurance, enabling standoff deployment and/or short-term loitering.
- A depth rating of 600 meters (1968 feet) would enable it to target a wide range of undersea infrastructure.
- The Sea Dart is currently available in 6 and 9 inch (152 and 226 mm) diameters, with a 12.75 inch (323 mm) under consideration.
- To compensate for its smaller payload, multiple Sea Darts could be deployed from a larger underwater vehicle to simultaneously attack a single target.
▶︎ RTX announced that testing continues on the Barracuda, a semi-autonomous mine neutralizing underwater vehicle that could be repurposed as a seabed strike weapon.
- As currently designed, the vehicle is deployed from a canister launcher aboard a mine countermeasures (MCM) unmanned surface vehicle (USV).
- Once in the water, the neutralizer vehicle separates from its surface communications buoy and proceeds to the target, tethered via fiber optic cable to enable real-time operator control. (In this way, the vehicle is a blend of standoff remotely operated vehicle (ROV) and AUV.)
- While the maximum depth of the Barracuda is undisclosed, based on its mission and deployment method it is likely rated between 100 and 300 meters.
- Repurposing Barracuda for deeper seabed strike missions would require increased pressure tolerance and a longer communications tether (or, alternatively, a switch to untethered acoustic communications (ACOMMS) or fully autonomous operations).
▶︎ Areté was awarded a Navy SBIR/STTR contract to develop REMORA, a novel AUV payload delivery system.
- REMORA, enables expendable payloads (markers, beacons, effectors) to deploy externally from a cylindrical AUV without the need for hull modifications or additional launcher hardware.
- The system attaches to the AUV via high-strength vacuum force, remaining neutrally buoyant during transit and becoming negatively buoyant upon release, all with minimal impact on hydrodynamics or endurance.
- A custom release mechanism enables the AUV to self-deploy the payload using a high-frequency, through-hull ACOMMS signal.
- As REMORA can be scaled up to accommodate large payloads, a blended wing body underwater glider (BWBUG), such as Northrop Grumman's Manta Ray, could accommodate multiple REMORAs in order to deploy clusters of kinetic effectors against seabed targets.
The seabed strike mission will increase in importance as underwater infrastructure proliferates, and will require platforms capable of locating and neutralizing stationary, hardened underwater targets.
- Torpedoes, as currently designed and employed, are expensive, single-use platforms optimized for engaging mobile targets on the surface or within the water column using wake, acoustic, or magnetic homing, and would be overpowered and sensor-limited in a seabed strike role.
- AUVs offer a low-cost, modular platform, capable of low-speed maneuverability, long endurance, and the ability to integrate tailored sensor and payload packages for detecting, localizing, and engaging fixed seabed targets.
CIVILIAN AND MILITARY SEABED INFRASTRUCTURE
| CATEGORY | INFRASTRUCTURE TYPE | DESCRIPTION |
|---|---|---|
| Telecom & Data | Submarine Fiber Optic Cables | Global Internet and communications backbone, unprotected beyond landing zones. |
| Repeaters and Power Feed Equipment | Amplify signals along long-haul cables; powered from shore. | |
| Cable Junction Boxes/Branching Units | Enable splitting of main lines to secondary destinations; can be targeted for disruption. | |
| Energy | Subsea Pipelines | Transport oil or gas between countries, offshore fields, coastal facilities. |
| Manifolds and Valves | Control flow and direction in pipeline networks; critical junction points. | |
| Subsea Wellheads | Located on the sea floor; connect to offshore platforms or Floating Production, Storage, and Offloading (FPSO) facilities. | |
| Subsea Power Cables | Transmit power to/from offshore installations or between countries. | |
| Subsea Power Stations | Nuclear, li-ion, fuel cell, or energy harvesting powered chargers used to power seabed infrastructure, such as the Teledyne Subsea Supercharger. | |
| Environmental & Scientific | Cabled Ocean Observatories | Collect long-term oceanographic data; fixed to the seafloor with shore uplinks. |
| Seismic Sensors | Used for earthquake detection or tsunami warnings. | |
| Environmental Monitoring Nodes | Track marine pollution, temperature, salinity, or mining impact zones. | |
| Military & Intelligence | Seabed Sensor Arrays | Fixed or distributed sensor networks used to monitor undersea activity, such as the Integrated Undersea Surveillance System (IUSS), or modular, deployable arrays for tactical or expeditionary applications. |
| Autonomous Weapon Nodes | Pre-positioned strike elements, such as encapsulated torpedo batteries, on or near the seabed. | |
| Command & Control & Communication (C3) Relays | Acoustic or underwater optical wireless transceivers to filter and amplify underwater transmissions. | |
| Navigational Aids | Underwater GNSS systems (analogous to DARPA's POSYDON), or long base line (LBL) transducers. | |
| Hardened Sensor Arrays | Resilient, possibly camouflaged nodes embedded in natural features. | |
| Maritime & Industrial | Mooring Blocks | Heavy anchors for surface or subsurface buoys and structures. |
| Subsea Mining Equipment | Used to extract polymetallic nodules or rare earth metals from the ocean floor. | |
| ROV/AUV Docking Stations | Recharging or data transfer points for unmanned vehicles. | |
| Underwater Tunnels / Transit Tubes | Fixed infrastructure under the sea floor, typically near shore. |
Seabed strike planning will need to account for the effects of hydrostatic pressure on warhead efficiency and explosive performance.
- Ambient pressure increases linearly with depth — approximately 10 atmospheres at 100 meters, 30 at 300 meters, and 100 at 1000 meters.
- Higher hydrostatic pressure resists the expansion of the explosive gas bubble, a key component of underwater blast damage, reducing both shock wave intensity and bubble-collapse energy.
- Greater depths generally require higher-yield warheads to achieve equivalent destructive effects, though not always proportionally.
- Modest yields could cause disproportionate damage to pre-stressed targets at depth, as ambient pressure pushes certain structures closer to failure thresholds
- At shallow to mid-depths, precision emplacement of small, ROV/AUV-deployed munitions may be sufficient; deeper targets may require increased yield, improved stand-off delivery, and pressure-hardened fusing for mission success.
CONCLUSION:
Recent developments in modular UUV platforms reflect a growing convergence of mine warfare, torpedo functionality, and autonomous undersea operations. Emerging systems such as Copperhead, Sea Dart, Barracuda, and Remora illustrate the trajectory toward multi-role effectors capable of executing both traditional ISR missions and kinetic engagements against both subsea and seabed targets. While operational constraints such as endurance, depth tolerance, and payload capacity persist, the integration of strike capability into autonomous platforms marks a substantive broadening of the undersea mission set and a potential inflection point in subsea warfare.
