In its 35-year existence from 1981 to 2016, the Strategic Studies Group (SSG) served as an incubator of revolutionary naval warfare concepts for 11 Chiefs of Naval Operations (CNOs). Its work subtly influenced maritime strategy and, as often, described hardware or systems that would later insinuate themselves into a more conventional acquisition process. By many accounts, SSG XXVIII in 2009 was the last group to issue a landmark exposition of future warfighting concepts, one that rationalized the employment of unmanned systems across a range of Navy warfare communities.
One such concept that merits reexamination in an era of great power competition is the effector payload module (EPM). The EPM was envisioned as a deployable, submerged, serviceable, conditioned, hibernating multiuse womb that would hold in readiness a variety of sensors or weapons that could deepen warfighting capacity in the early phase of an intense exchange with a great power competitor. To borrow from Vice Admiral Thomas Rowden's description of distributed lethality, EPMs would permit the Navy, when operating offensively near China’s declared first island chain, “to ‘spread the playing field,’ providing a more complex targeting problem” while creating more favorable conditions to project power where required.
The EPM Concept
In the 2009 study, the SSG provided only the sparest description of an EPM. Consistent with that year’s study theme of unmanning to disaggregate, and disaggregating to penetrate hostile antiaccess, area denial environments, they proposed a "separation of weapons across the domains into multiple readily deployable launchers," named effector payload modules. The SSG’s investigation did not go deeper than a graphic illustration and a suggested weapon load, inviting further speculation as to how an EPM might be constructed.
Assuming Standard Missiles (SM)-3 and -6 as the preferred multiuse weapon load, single missile canisters grouped in a truncated four-canister version of the standard eight-canister module of the Mk-41 vertical launcher system, would establish the baseline configuration for an EPM magazine. This quadruple canister package would be joined around a central uptake shaft for rocket exhaust gas management. The girth of the quadruple pack might be extended only slightly to accommodate a launch sequencer unit, motor control panel to exercise authority over moveable hatches and drains, and programmable power supplies.
A means for remote activation and launch would require an extendable antenna, receiver, and processor. A launch-control unit would be positioned remotely, perhaps shipboard or airborne and could be relayed through overhead means, with connectivity to the EPM’s antenna. The four-canister arrangement would be encased in a watertight aluminum shell surrounding the outside dimensions of the EPM, acting much like a spar-type buoy. The spar buoy shape would best mitigate the heave and roll in an open ocean emplacement, providing the optimum shape for "stability in a deep-draft, slender-body design," and the shell itself would enclose enough volume to allow for slightly positive buoyancy of the EPM. A ventral compartment containing rechargeable long-life batteries would help stabilize the EPM in an upright position.
A mooring anchored to the sea floor might be the optimal design for fixed emplacement, however may narrow deployment to ocean depths of 1,000 feet or less because of a finite limit on the length and strength of the mooring line. This could constrain mooring options in the western Pacific Ocean to those areas where the undersea geography is predominated by ridges or plateaus, subjecting the EPM and its mooring to stronger currents. A slack mooring might be preferred, with a primary consideration being the length of mooring line required. In this case, "the mooring line, chain, and shackles hang under their own weight relying on the reserve positive buoyancy" of the EPM to support them.
Deployment and Recovery
EPMs would most likely be inserted in the western Pacific before hostilities occur, with indications and warnings of an imminent threat, and in the time remaining before the airspace and seaspace surrounding probable deployment areas becomes contested. The SSG, in its study, suggested sea surface launch from Wasp-class amphibious assault ships or San Antonio–class amphibious transport docks, whereby a floating EPM could be towed out of the well deck by support craft and released. An option not considered by the SSG would be a less obtrusive deployment from a littoral combat ship (LCS). An estimate of mission bay volume inside an Independence-class LCS suggests as many as ten EPMs could be stored in readiness in the mission bay for deployment by crane out of the stern door of the ship. Ten EPMs loaded with SM-6 missiles could be emplaced in submerged position containing as many as 40 missiles in ready magazines. For covert deployment in contested areas, the SSG recommended considering ejecting EPMs from the payload tubes of Virginia-class submarines. This would necessarily be slower and a more deliberate process than a surface launch.
In every situation, the life of the EPM is a consideration, particularly as it relates to battery life and seakeeping. Design provisions could be made for recharging by passing ship or submarine if longer duration required. More likely, EPMs would be recovered within a few months by the same means they were deployed. If an EPM were discovered by a possibly hostile entity before its use, further provision in the design could permit flooding or detonating when a tripwire is actuated. Once deployed and in place, however, the question for operators is when and how best to exploit the capability.
The EPM in Antisurface Warfare
In a possible future war with the People's Liberation Army Navy (PLAN), the Navy would face the conundrum of having its surface combatants outranged by PLAN weapons of greater speed and mass. Until that imbalance can be reversed with targeted investment in U.S. missile upgrades, the EPM may offer a means to offset the PLAN advantage. If a field of EPMs, charged with SM-6 missiles, could be sowed along PLAN surface combatants’ likely avenues of approach, they could create an opportunity for striking inside the effective range of Chinese antiship missiles.
Such a scenario might unfold with early detection, classification, and tracking of the PLAN combatants by a MQ-4C Triton unmanned aerial vehicle operating at 55,000 feet in the western reaches of the Philippine Sea. The Triton would, in turn, cue an airborne F-35C on patrol at 35,000 feet from an approaching carrier strike group whose screening surface combatants are still well outside the effective range of the PLAN’s ship-borne missiles. The F-35C would obtain a track, and, by connecting with the EPM directly, initiate the launch sequence and initially guide the SM-6 to its target. This scenario adapts the essential elements of naval integrated fire control (NIFC), substituting the EPM for the U.S. surface combatant as the missile shooter to get inside the effective range of the PLAN missiles. The effect is to exploit surprise by presenting an off-axis missile attack that degrades PLAN capability and complicates their countertargeting.
Defense Against Antiship Ballistic Missiles
Further complicating U.S. Navy operations inside the first island chain is the prospect of defending against antiship ballistic missiles launched from the Chinese mainland. A SM-3-laden EPM field, deployed surreptitiously on the edges of the Taiwan Strait, might be employed to neutralize, or at lease mitigate, that threat in the early phase of an attack on an approaching carrier strike group.
A scenario might unfold that involves initial detection of a Chinese DF-21 launch by overhead means. The approaching carrier strike group could signal the E-2D early-warning aircraft to select an enhanced tracking sector mode on its radar to detect and track the missile while still in its boost phase. With a good track, the E-2D would link directly to the EPM to initiate a launch of single or multiple SM-3s. The result would be earlier engagement with the antiship missiles to obtain better intercept geometry for the SM-3. This would attrite the salvo of antiship missiles that might be anticipated in a saturation attack and preserve SM-3 missile inventory organic to the carrier strike group that it likely will need for midcourse or terminal phase intercept of Chinese missiles that might leak through.
Conventional Prompt Strike
In a conventional confrontation with China, U.S. Navy carrier strike groups can expect attacks in depth, emanating from follow-on attacks by antiship missiles from mobile launchers, or waves of land-based aircraft carrying air-to-surface cruise missiles. An effective counter, one that is immediate and responsive from long distance, could disrupt follow-on attacks. One goal of hypersonic missile development has been to enable the “ability to strike targets anywhere on Earth with conventional weapons in as little as an hour, without relying on forward-based forces.”
Most hypersonic research to date has centered on ballistic missiles with conventional warheads as the preferred delivery means to provide the requisite speed, but also the range to strike from outside the theater. A principal concern in this regard is the risk of miscalculation, and potential nuclear escalation, if the flight profile of an inbound conventionally armed ballistic missile is misinterpreted. Cruise missiles launched from distance would present a different flight profile, one less likely to be confused with a possible nuclear attack. Here, the EPM, loaded with hypersonic cruise missiles, and clandestinely deployed in the Taiwan Strait or East China Sea, could offset the range shortcoming of the missile. From those waters, inland targets on the Chinese mainland as deep as 100 miles from the coastline, could theoretically be reached within five minutes of launch.
EPM: Additive for Growing the Force
The EPM essentially is a concept for distributed lethality. It failed to gain advocacy—perhaps because of the Navy Department’s determination to preserve and grow the number of ship hulls in an era of budget sequestration.
The budgetary challenge to preserve and grow ship hulls has not abated. To squeeze more capacity from limited funds, Navy leaders are conjuring a force structure that will delegate more tasks to “lightly manned vessels that can be fielded in greater numbers and can be distributed more widely across a theater.” Yet, the Navy’s large unmanned surface vessel, and proposed medium unmanned surface vessels, fall short in delivering on the promise of fully disaggregated operations. By requiring a hull, power plant, fuel, and crew accommodation—even for optionally manned vessels—the Navy must plan for life-cycle procurement and sustainment costs that will compete for resources with manned surface combatants, and may not deliver a range of multimission capability for the resources expended.
EPMs, however, rooted in the notion of remotely positioning a ship’s weapons magazine to increase warfighting capacity while reducing the attendant infrastructure, can achieve distributed lethality at a fraction of the attendant cost of additional hulls. If disaggregation operations are the priority, EPMs are right platform for the future Navy.