Problem Scope: Extended Area Protection & Survivability
The Extended Area Protection and Survivability (EAPS) Science and Technology (S&T) Program Architecture Study will provide concept definition, requirements analysis, functional analysis, and design synthesis, and establish a baseline architecture to enable stationary/mobile 360 degree hemispherical extended area protection and survivability of future Army combat unit assets from direct and indirect fires, including rocket, artillery and mortar (RAM), Unmanned Aerial Vehicle (UAV), and Cruise Missile (CM) threats while minimizing cost, weight, and space allowing forimproved deployment and mobility. Currently, no existing or programmed system has the capability to negate unguided rockets and mortar/artillery projectiles with mechanical fuzes after they are launched. Only a limited capability exists to negate UAV reconnaissance capabilities at sufficient range to preclude detection, identification, and targeting. Protection and survivability capabilities in Army combat units faced with this threat needs to be demonstrated to deter or defeat those enemy capabilities.
Bill Nourse, program manager of the U.S. Army’s Extended Area Protection & Survivability (EAPS) program, describes the area air defense operational scenario as being broken down into an inner tier, comprising of the ranges up to 10 km, and an outer tier for defended ranges beyond 10 km . The outer tier is focused on defending against large threats, such as ballistic and cruise missiles, unmanned aerial vehicles, and rotary wing aircraft. The inner tier is primarily focused on the smallerthreats, such as rockets, artillery, and mortars, and potentially even on outer tier “leakers”. As shown graphically in Figure 5, the inner tier is further broken down into a Short Range Inner Tier (SRIT) for ranges between 500-2000 m and a Long Range Inner Tier (LRIT) for ranges between 2-10 km.
Nourse describes several of the potential advantages of solutions addressing each of the inner tier options. A solution required to only defend the SRIT has the attributes of earlier fielding and lower unit cost when compared to a solution designed to defend the LRIT. In addition, threats that have very short times of flight may only operate within the SRIT. However, the ability to protect moving assets may only be addressed by a solution that can defend at the LRIT level. Nourse suggests that a mix of both short and long range shooters might be the most cost effective solution.
Dr. Jim Baumann, the Deputy EAPS program manager, lays out the basic air defense weapon engagement kinematics as given in Figure 6. This is independent of the type of interceptor solution, for example a gun fired projectile can be launched to intercept the target, or a directed energy (DE) weapon can be used to heat up the target’s warhead causing detonation. The basic timeline of events is as follows.
A surveillance radar (SR) detects a threat fired from a certain distance with the intention of hitting some defendable asset, and firm track is established. A flight control radar (FCR) establishes a firm track of the threat trajectory to establish a fire control solution. When a solution is established, the air defense interceptor is launched (or if a DE weapon is used, system lasing initiation begins). The time up to this point is known as the System Reaction Time (SRT). The interceptor flight time, or DE lasing dwell time, determines the point at which the threat is killed, and the distance to the defendable asset is the Keepout Distance.