As the recent Israeli shootdown of a Hezbollah UAV reminded us, it is relatively easy to destroy an unmanned aircraft. But what about the proliferating numbers of unmanned undersea vehicles? The growth in these systems for naval applications will inevitably result in the requirement to counter an adversary’s underwater drones. Detection of a small man-made object moving underwater is not trivial, but also becoming easier with the advent of technologies such as high-resolution imaging sonars and Light Detection And Ranging (LIDAR) systems.
However, once an AUV is detected, how can it be destroyed? This problem set isn’t new. Mini-subs and combat swimmers have threatened ships in port since World War II. The old school way of dealing with frogmen is to drop a concussion grenade over the side of a boat. Alternatively, some navies have experimented with dolphins to counter swimmers. These sorts of mammal-based systems could conceivably be trained to work against AUVs. Other advanced technology developments will allow mammals to stay out combat.
Super-cavitating bullets, like those produced by US-based PNW Arms and Norway-based DSG Technology (see video) offer a potential weapon for defeating AUVs. According to PNW Arms, “supercavitation is the use of cavitation effects to create a bubble of gas inside a liquid large enough to encompass an object traveling through the liquid, which greatly reduces friction drag on the object and enables the achievement of very high speeds.” DSG Technology’s Multi-Environment Ammunition allows ordnance ranging in size from 4.5 mm through to 155 mm to transit from air to water or vice versa. Conceivably, AUVs could be detected and engaged from the air. The U.S. Navy’s AN/AWS-2 Rapid Airborne Mine Clearance System (RAMICS) technology demonstrator used a helicopter equipped with a blue-green LIDAR to locate mines near the surface, then a 30 mm super-cavitating round to neutralize them at depths of up to 60 meters. The program was cancelled in 2011 due to technical and budgetary issues.
Super-cavitating rounds also open up the possibility of hunter-killer unmanned undersea vehicles, guarding a port from other AUVs, mini-subs, and swimmers. Submariners often remind other sailors that the best ASW weapon is another submarine and the same may be true with AUVs. However, discriminating between an AUV and a similarly sized fish or marine mammal before pulling the trigger might be difficult without some sort of corroborating data, or image recognition algorithms.
Unmanned naval systems are rapidly reaching the limitations of physics with regard to their endurance. Current internal combustion and electrically powered systems have several drawbacks. In addition to range/weight issues, liquid fuel engines make for noisy UAVs which can compromise missions in some circumstances, such as intelligence, surveillance, and reconnaissance. Electrically-powered UAVs are quiet, but batteries do not approach the energy contained within a similar weight of fossil fuel. This article clearly explains the physical limitations of current battery technologies. Modern lithium-ion batteries are problematic due to their propensity to catch fire and explode. SOCOM’s billion dollar Advanced SEAL Delivery System (ASDS) fire illustrated why navies are not keen on carrying lithium-ion batteries at sea, especially undersea. Clearly, alternative power technologies are in high demand.
Previously, we highlighted the use of ship-based lasers to power future UAS. The video below discusses these tests, along with a propane-powered variant. Planned upcoming flight tests will demonstrate the ability to keep a Stalker Small Tactical UAS aloft using a laser for two to three days.
For long-endurance surface and underwater vehicles where speed is not a mission requirement, wave power and buoyancy-driven gliders are viable alternatives. Another possibility for powering future autonomous sea-floor crawlers or UUVs is the benthic microbial fuel cell. Naval drones will require continued innovations in power to allow performance necessary to meet future operational requirements.
Paleo-Wireless: Communicating in the Swarm
In 2002, LtGen Paul Van Riper became famous for sinking the American fleet in a day during the Millennium Challenge exercise; he did so by veiling his intentions in a variety of wireless communications. We assume wireless to mean the transfer of data through the air via radio signals, but lights, hand signals, motorcycle couriers, and the like are all equally wireless. These paleo-wireless technologies are just what ComBots need for signal security.
ComBot vulnerabilities to wireless hacks are of particular concern for planners. Data connections to operators or potential connections between ComBots serve as a way for enemies to detect, destroy, or even hijack our assets. While autonomy is the first step in solving the vulnerability of operator connections, ComBots in the future will work as communicating teams. Fewer opportunities will be provided for subversion by cutting the long link back to the operator while maintaining the versatility of a small internally-communicating team. However, data communication between ComBots would still be vulnerable. Therefore, ComBots must learn from LtGen Van Riper and move to the wireless communications of the past. Just as ships at sea communicate by flags and lights when running silent or soldiers might whisper or motion to one another before breaching a doorway, ComBots can communicate via light, movement, or sound.
Unlike a tired Junior Officer of the Deck with a NATO code-book propped open, computers can almost instantly process simple data. If given the capability, a series of blinking lights, sounds, or even informative light data-transmissions could allow ComBots of the future to coordinate their actions in the battlefield without significantly revealing their position. ComBots would be able to detect and recognize the originator of signals, duly ignoring signals not coming from the ComBot group. With the speed and variation of their communications, compressed as allowed by their processing power, ComBots can move through the streets and skies with little more disruption than a cricket, lightening bug, or light breeze. High- and low-pitch sounds and infrared light would allow for communications undetectable to the average soldier.
LtGen Van Riper melded a deadly combo of new weaponry with old communications to build a force capable of, with the greatest surprise, wiping out a force armed with the greatest technology in every category. Utility, not technology, is what gives us the edge in the battlefield. Sometimes it is a combination of the old and new that allows for the potency. Perhaps, one day, ComBots will be set loose into the battlefield where they will operate more as a pack driven by sight and sound than a military formation managed over a data link.
GPS: How About a Map?
The Texas incident has broken open the doors on a previously low-key vulnerability for ComBot systems, navigation. While speculation is rife as to how the CIA lost a drone in Iran, it is quite clear that the researchers in Texas were able to spoof a ComBot into destroying itself. Spoofing of externally-based navigational systems is a potential way to turn aerial ComBots in particular into weapons against us. It is often forgotten that systems that are “autonomous” still rely on outside guidance references that can be manipulated. While civilian GPS is less secure than military-grade GPS, the potential for GPS spoofing to lay-low a combat force is a chilling one. However, the solution can be found by augmenting legacy techniques with modern processing.
Terrain Contour Matching (TERCOM) and Digital Scene Mapping Correlation (DSMAC) are non-GPS methods of navigation that specifically use internal recognition of local terrain and urban landmarks to maneuver Tomahawk missiles. This is another way of, “looking around and reading a map.” Processing power advances since the system was first introduced during the Cold War mean greater amounts of recognition data can be processed in shorter amounts of time by smaller platforms. ComBots deployed to specific areas can upload local data to allow localization based on terrain from high altitude or Google-maps-style scene matching from rooftops or even street-by-street. With adaptive software, ComBots could even “guess” their location if the battlefield changes due to combat destruction, noting changes in their environment as damage is done. While GPS can be spoofed, unless the enemy has been watching too much Blazing Saddles, DSMAC and TERCOM will be nigh impregnable navigational systems.
This defense for ComBot operations can also act as a navigational redoubt for a fighting force. The downing of GPS satellites or the spoofing of signals effects everyone using electronic navigation systems. Aerial ComBots outfitted with TERCOM and DSMAC could act as a secondary GPS system in an area with a GPS outage. If signals are jammed or satellites taken out, warfighters or other navigationally lesser-developed ComBots could triangulate their positions based on the system of ComBots with locations determined by TERCOM and DSMAC. By adding these recognition systems to autonomous drones, commanders will defend ComBots from hijackers and combatants from the choking fog of war.
Riding the Wave
The key to the safe and effective use of ComBots is to avoid the extremes of optimists and luddites. Optimists will look far into the realm of capability before necessarily researching vulnerabilities, abandoning the old for every shiny new development. Luddites will make certification and security processes long and complicated, cowering from the strange light new technology brings; ComBots would run on Windows 95 and take 30 minutes to log on to themselves. It is best to advance fearlessly, but take our hard-learned lessons with us. Non-digital communications, aka speech and signals, and localized navigational systems, aka carrying maps, offer ComBot developers a shield against interlocutors. Our new dogs will be best defended by some of the oldest tricks.
Matt Hipple is a surface warfare officer in the U.S. Navy. The opinions and views expressed in this post are his alone and are presented in his personal capacity. They do not necessarily represent the views of U.S. Department of Defense or the U.S. Navy.
After months of patient progress the drones reached their targets. Over the span of a few weeks they silently arrived at their pre-assigned loiter boxes (lobos) in the many harbors of Orangelandia. Having been launched from inconspicuous commercial vessels in major shipping lanes, the transit time was shortened by a good month. Yet for the few who knew of the operation, the anxious waiting was plenty long enough. The policy makers monitored the gliders’ headway via secure satellite datalinks and assured themselves that the operation, sold as a precautionary measure, was warranted in light of heightened tensions with Orangelandia.
As the weeks passed tensions only increase. Orangelandia declared its claimed EEZ closed to all foreign military vessels and threatened to sink any violators. After making good on its promise in a naval skirmish against a neighbor with rival claims to an island chain, Orangelandia was given an ultimatum by the U.N. Security Council* to stand down. With no sign of the occurring, the policy makers decide it’s time to act.
Darkness falls in Orangelandia. Satellites command the gliders forward. They drift further into the harbors, their targets are naval vessels they’ve monitored for days. The sailors on watch see and hear nothing more than what they attribute to the usual debris floating by on a moonless night. The gliders release their payloads – smaller drones that specialize in climbing the hulls of ships. After clamoring aboard the weatherdecks, the small machines avoid the sealed doors of the ships’ airlocks and feel out the superstructures, their goals the exhaust stacks for the ships’ engines and generators.
On a few ships at anchor the drones encounter humming engines and generators, beckoning the heat-seeking drones. Burrowing past the louvers the drones drop down through ducts and move towards the ships’ mechanical hearts. As the heat of the exhaust on the active vessels melts the drones’ exterior sheathing, thermal-triggered explosives carried in the drone cores detonate, delivering mission kills and rendering the ships immobile for weeks-to-months of critical repair. On the inactive ships it takes longer for the drones’ schematics-recognition features to determine the stacks’ location but the outcome is more devastating. The drones are able to move further into the exhaust system’s interior, detonating once progress is blocked, and increasing the likelihood of destroying the engines or generators themselves. Within the span of a night the majority of Orangelandia’s in-port fleet is crippled.
The above passage is of course a piece of fiction, and not very good fiction at that. But it doesn’t have to be. The technology to enable the scenario exists and will become more sophisticated and cheaper in the coming years. This is also far from the only way to imagine a “Drone Pearl Harbor,” as slightly different capabilities hold the potential to impact the way an attack could play out.
In developing a concept of operations for a stealth drone attack the ability to give the execute order is a sticking point. The technologically easiest course of action would be to simultaneously make both the decisions to set up for and to execute the strike at the beginning of the decision cycle, launching the drone operation as a “fire and forget” (or rather “fire and wait patiently”) strike. Yet few policy makers will want to make an irreversible decision far in advance of the impact of the effects. The decision to attack Orangelandia may be correct in the context of the 7th of the month, but not the 21st. One needs only remember the desperate attempts to recall the nuclear-armed bombers of Dr. Strangelove to grasp the concept.
However, any attempt to move the “execute” decision point later than the “set up” order, as I did in my example, faces technical hurdles. A direct transmission signal requirement would make the drones vulnerable to detection and possible hijacking or jamming. Using broadcast signals to transmit orders and obscure their location means leaving the drones even more susceptible to hijacking and jamming as Orangelandia could constantly emit signals to that end. Similar vulnerabilities exist when the drones are given reporting requirements, so an informed balancing of the need for one- or two-way communication and concerns over the exposures those needs create is necessary.
Variations on a Theme
The above scenario was played out against a generic surface ship. Other types of naval vessels have more accessible points of entry; and the job of penetration is made easier at less-stringent damage control settings that leave hatches and air locks open. Additionally the ways, means, and follow-on considerations of a drone sneak attack are also variable, but can be roughly broken down into fouling attacks, as in the scenario above; direct attacks; and cyber-attacks.
In a fouling attack, the drone payload would be used to achieve a mission kill against a critical piece of shipboard equipment. The drone would need the ability to locate that piece of equipment through some type of sensor – visual, thermal, chemical, etc. External targets, such as a ship’s propellers, would be the easiest to target. The benefit of a fouling attack is that the payload could be a small explosive, limiting drone’s size, likelihood of detection, and propulsion requirements for a trans-oceanic voyage. It could even be the drone itself, outfitted with special equipment or configuration options to inflict the maximum damage on the piece of critical gear. As an example imagine a piece of corrosive wire wrapping itself around the same hypothetical propeller. Again, the execute order in this type of attack could be withheld until very late in the decision-making process while the glider drones do “circles of death” in their lobos.
In a direct attack the glider drone would carry a weapon payload designed to inflict maximum kinetic damage. Such an attack would require less sophisticated targeting internal to the drone and could be used to attempt to disable a large portion of the ship’s crew and/or sink the ship. As with fouling attacks, direct attacks would be easier to conduct once the glider was on station and could incur the same delayed-decision benefits, the increased explosives requirement would increase the drone’s size and detectability.
In the last type of attack, a payload drone would find a way to penetrate the ship and access the ship’s industrial control systems (ICS), which operate things such as the ship’s main engines, to introduce a Stuxnet-like virus. Such drone would need to be small enough to fit through minuscule spaces or blend in during the process of crew traffic opening and shutting airlocks. The drone would also have to be the most advanced to successfully navigate around the ship unseen and interface with ICS through diagnostic, patching, or external monitoring ports. Such a drone could delay the policy-maker’s execute order until well after infection, potentially expanding the decision timeline until well after the drone has achieved its mission and the vessel has gotten underway. This delay would come at the cost of the very difficult task of being able to transmit the final execute order to the newly infected ICS, so the decision to infect the systems would more realistically have to be paired with the decision to execute virus’s programming. On the plus side, a cyber/drone sneak attack could potentially disguise the source of the attack, or even that an attack has occurred, unlike the other two types of attack, providing policy makers with further options than simply a kinetic attack.
That these courses of action are possible says nothing of whether executing any of them would be wise. The risk and potential repercussions of each course of action is as varied as the ways in which such an attack may occur. This is one reason I have attempted to draw out the effects different technologies have on moving the decision points. But possible they are, so it would be wise to both think of ways to take advantage of the options as new tools for policy makers, and think of ways to defend against them that don’t rely on weary roving deck watches. A few defensive options that come to mind include more stringent damage control settings in port, a thorough examination of the vulnerability of vessels and shipboard access points to drone penetrations, detection systems for drone penetrations, drone SIGINT detection and jamming, and possible external hardening of berths. But this is probably a good jumping off point for another post and your thoughts.
Scott Cheney-Peters is a surface warfare officer in the U.S. Navy Reserve and the former editor of Surface Warfare magazine. He is the founding director of the Center for International Maritime Security and holds a master’s degree in National Security and Strategic Studies from the U.S. Naval War College.
The opinions and views expressed in this post are his alone and are presented in his personal capacity. They do not necessarily represent the views of U.S. Department of Defense or the U.S. Navy.
*So no, Orangelandia is clearly not China, a veto-wielding member.