Because this study is focused on networking, the committee is interested in the range of weapons (that is, the extent of the area over which they can exert influence), in their information requirements for guidance (that is, what information sensors must see and what information the infrastructure must deliver promptly to the shooter or to the weapon), and in their command support requirements (that is, what needs derive from planning and coordination functions). However, the committee first categorizes weapons according to their missions and required information support and then discusses guidance, acceptable time late, volume of data required, and allowable target location error as a function of their target sets.
D.1 MISSIONS, WEAPONS, AND REQUIRED COMMAND AND INFORMATION SUPPORT
D.1.1 Power Projection
Naval doctrine publications define power projection as “application of offensive military force against an enemy at a chosen time and place.” In consonance with the Joint Vision 2010 definition of precision engagement,1 the top-level requirements for power projection may be said to include the following:
Strike anytime, anywhere,
Incapacitate many targets of many different kinds,
Predict and assess results, and
Sustain operations in a high tempo,
Losses to own force,
Collateral damage, and
Force size and cost.
Current and programmed naval weapons for power projection are launched from manned attack aircraft, surface combatants, and attack submarines.
D.1.1.1 Attack Aircraft and Air-Launched Strike Weapons
The Navy’s principal attack aircraft today are the carrier-launched F/A-18 C/ D and F-14, and the vertical-take-off-and-land (VTOL) AV-8, used principally for close air support.
The F/A-18 E/F is scheduled for initial operational capability in the next few years, and the Joint Strike Fighter program is in the advanced development stage. As an example of weapons payload capability, the F/A-18 E/F will deliver several thousand pounds more than 500 miles from the carrier without refueling.
Naval tactical aircraft will rely principally on the Joint Tactical Information Distribution System (JTIDS) as the link for updating target information for situational awareness and strike coordination. The Global Broadcast System may also provide key data for targeting and situational awareness. The naval aviation community recognizes the value of connecting aircraft to external sources. For example, a major component of the Joint Strike Fighter program is a trade-off study to determine how much command, control, communications, computing, intelligence, surveillance, and reconnaissance (C4ISR) equipment the aircraft should carry on board and how much it can rely on off-board sources to provide. Reducing aircraft cost is a driver in the study.
Air-launched weapons are often categorized by their flight range into direct attack (R < 15 nautical miles), standoff from point-defense (15 < R < 60), and standoff from area defense (R > 60). The joint direct attack munition (JDAM) has become the weapon of choice for many direct attack missions. A JDAM is built by attaching a kit with Global Positioning System/Inertial Navigation System (GPS/INS) guidance and fin controls to an existing 1,000 or 2,000 lb free-fall bomb. (A kit for 500 lb bombs is planned for later introduction.) Other older man-in-the-loop precision-guided munitions (e.g., Maverick with electro-optical (EO) or infrared (IR) guidance) will remain in the inventory but production will cease. In the near future, the joint standoff weapon (JSOW), a gliding weapon with a GPS receiver and an INS, will become the weapon of choice for standoff
from point defense missions. The rocket-propelled high-speed antiradiation missile (HARM) will also be in this range category. It is being upgraded to add GPS to its INS. For standoff from area defense the Navy prefers the soon-to-be-fielded standoff land attack missile-expanded response (SLAM-ER). The Air Force favors the joint air-to-surface standoff missile (JASSM) that is also being developed and tested for compatibility with carrier aircraft and the carrier environment. These are jet-powered cruise missiles guided with GPS/INS and imaging IR terminal seekers. The JASSM will have automatic target recognition (ATR) capability. The SLAM-ER will initially have a data link for man-in-the-loop operation; ATR is planned for later introduction.
Guided (“smart”) submunitions represent a category of future possibilities. The Army and Air Force have under development various systems that the Navy could employ. The Brilliant Anti-Armor Technology submunition uses a combination of acoustic and infrared sensors to search a several-miles wide area and home on motorized ground targets. The bomb live unit (BLU)-108 submunition, used in the Air Force’s sensor-fused weapon and the Army’s search-and-destroy armor munition (SADARM) 155 mm artillery munition, dispenses spinning disks that find targets with IR sensors and then fire projectiles into them.
Another possible future concept is an uninhabited combat air vehicle (UCAV), which can be thought of as in between (in size and capability) a recoverable cruise missile and a pilotless attack aircraft. Some UCAV concepts assume development of a new class of 250 lb munitions. The Defense Advanced Research Projects Agency (DARPA) has a program under way to develop a prototype, and the Naval Air Systems Command’s Advanced Development Office has initiated an exploratory effort.
Another possibility is a Mach 5 to 7 hypersonic weapon (ramjet, possibly with supersonic combustion) with perhaps 300 nautical mile range to kill time-critical and buried targets. The Office of Naval Research (ONR) and DARPA are cooperating on an exploratory development effort.
D.1.1.2 Combatant Ships and Ship-launched Weapons
The Navy’s Aegis cruisers and destroyers and DD-963 class destroyers can carry Tomahawk cruise missiles. Most of these ships have the vertical launch system (VLS), which stores missiles in 90 to 120 cells. Tomahawk and all versions of standard missiles are stored one per VLS cell.
Since its first use against Iraq in January 1991, Tomahawk has become a weapon of choice for deep strikes in limited military actions and for defense suppression prior to major military actions utilizing manned aircraft. Tomahawk is a 1,000 nautical mile range jet-powered cruise missile with GPS/INS guidance, terrain-contour matching, and an optical map-matcher for terminal update. A new variant, Block IV, is under development for initial operational capability around 2003. Block IV will enable in-flight retargeting through ultra-
high-frequency satellite communications and will reduce weapon cost, among other things. Block IV will enhance considerably U.S. tactical responsiveness and flexibility in unmanned deep strike operations against fixed and relocatable targets.
The surface Navy currently has almost no capability to provide fire support to defend U.S. Marine Corps light maneuver units. The 5-inch guns on Aegis ships have an effective range of about 14 nautical miles. However, the surface Navy is developing the extended-range guided missile (ERGM) by adding rocket power and GPS guidance to a submunition-dispensing artillery shell. The ERGM will enable accurate fires to a range of 63 nautical miles. In a remanufacturing program, the Navy is adding GPS to convert existing, obsolete standard missiles (built originally for air defense) into the land-attack standard missile (LASM). The LASM will enable accurate fire to over 100 nautical miles. ERGM and LASM will be retrofitted to Aegis ships.
The Navy has a major program under way to develop a new destroyer class, the DD-21, which will have strike as its principal mission. The DD-21 may carry as many as 700 ERGM rounds in its magazine. Like the Joint Strike Fighter program, the DD-21 program has significant efforts under way to trade onboard and offboard C4ISR capabilities in the interest of reducing platform cost.
The DD-21 appears to be the Navy’s opportunity to address its naval surface fire support problems in a fundamental way. An advanced gun system (AGS) is in the early stages of concept exploration as part of the DD-21 program. The Navy also appears committed to developing an advanced land attack missile (ALAM) as an associated program within the DD-21 Program Executive Office. The Army Tactical Cruise Missile System (ATACMS), a GPS-guided, submunition-dispersing tactical ballistic missile, is a candidate for this role. Another possibility is a smaller rocket that the DD-21 could carry in greater numbers.
D.1.1.3 Attack Submarines and Submarine-launched Weapons
U.S. Navy attack submarines are capable of launching Tomahawks. Those of the 688-I class have a dozen vertical tubes in the bow for carrying Tomahawks, and the missiles can be fired from their torpedo tubes as well. Attack submarines have participated in many of the operations this past decade in which Tomahawks have been launched.
In recent years, the submarine community has shown an interest in expanding the submarine’s role in strike operations. Conversion of ATACMS for submarine launch has been considered in order to give the attack submarine a naval fire support capability. Others have questioned whether the submarine’s few weapons could make a difference in a naval fire support role.
D.1.1.4 Primary Command and Information Support Requirements of Strike Weapons
A key requirement for effective, precise operations with many of the above-mentioned weapons is a rapid, accurate means of obtaining GPS coordinates for large numbers of targets. A number of development efforts are under way that address this issue. The Navy’s ability to kill emergent or time-critical targets is limited primarily by targeting and command and control (C2) time lines, but if these time lines were improved, then missile fly-out times would limit effectiveness.
The Navy’s growing reliance (and that of the other Services) on GPS is a source of concern because of the inevitability of a significant GPS jamming threat. A number of complementary ways to deal with the GPS threat are as follows:
Increase the resistance of GPS receivers to jamming by use of advanced signal recovery algorithms and tighter coupling with the inertial navigation system;
Develop low-cost, low-drift-rate microelectromechanical inertial navigation systems;
Use controlled radiation pattern arrays to maximize antenna sensitivity in the direction of the GPS satellites, while steering an antenna null in the direction of jammers;
Use alternate means of navigation update, e.g., precision terrain map-matchers; and
Attack the jammers, at least the powerful ones.
The Navy’s means of killing moving targets are effectively limited to man-in-the-loop aircraft operations at close range. Killing moving targets at long range will require new weapons or adaptations to existing weapons as well as new targeting and command and control capabilities. Sections D.22.214.171.124 to D.126.96.36.199 address this issue in more detail.
Mission planning and mission rehearsal systems for tactical aircraft are becoming increasingly sophisticated and increasingly important to mission success. They rely on databases for photography, threat location and capabilities, terrain elevation, and weather forecasts.
Tomahawk mission planning, now performed strictly at just two facilities ashore (Cruise Missile Support Activities), is moving to carrier and then to cruiser and destroyer operations. Will control of Tomahawk, ERGM, and LASM be integrated on Aegis ships? Will control of Tomahawk, AGS, and ALAM be integrated on the DD-21? The Navy is grappling with these issues at present.
Systems for dynamic battle management do not exist. Such systems are needed for coordination of tactical aircraft strikes, Block IV Tomahawk strikes,
and naval surface fire support. They are especially needed because the Navy is, and perhaps always will be, limited in firepower. Efficiency is essential. Tactical aircraft can carry only a few weapons into the fray; surface ships are developing new capabilities to project more power at greater ranges, but they too will be limited in any extended operation. Another significant requirement is deconfliction, ensuring that U.S. forces do not fall victim to friendly fire.
D.188.8.131.52 Target-Weapon Pairing
Targets influence the choice of weapons and consequently the data and network support needed to allow their launch and successful execution of mission.
D.184.108.40.206 Fixed Targets
Fixed targets are either structures (buildings, bridges, dams, tunnel entrances, large antenna structures, and so on) or distributed facilities (railroad switch yards, fuel storage areas, warehouses, entrenched troops, and so on).
Weapons that are used to attack fixed structures usually have relatively large unitary warheads, which for greatest effectiveness, need to be delivered to their aimpoint with an accuracy of a few meters. Examples are bridge abutments, transformer banks that feed a large factory complex, or command bunkers used to direct an adversary’s operations. The weapons set used for such targets include the Tomahawk, JDAM, SLAM-ER, laser-guided bombs, and, where precision is not a prerequisite, Mark-80 series bombs. The guidance for weapons in this class is based on the use of one or more of the following: GPS/INS, image correlation for terminal guidance, semiactive laser guidance, or in the case of Maverick, man-in-the-loop.
Attacks on fixed targets are generally not time critical. The information needed to support an attack or re-attack with such weapons must be supplied in times that are compatible with the generation of the daily air tasking order (ATO). Although the data rates needed to support the employment of such weapons may be modest, the total amount of information needed may be large. For image-guided weapons such as the Tomahawk, the number of images needed to plan an individual strike is about 10. Depending on the size of the field of view and contrast and resolution needed, each image may contain between 107 and 108 bits. If 100 weapons are launched in a day, the amount of data needed to launch such an attack will be between 1010 and 1011 bits.
If the targeting network does not incorporate distributed, locally available databases, the transfer of that many bits of data from a central data repository to a forward-deployed strike planning cell in a fraction of a day will require the availability of data links that can support data transfer rates of at least 1 to 10 Mbps. Afloat planning cells for Tomahawk missions normally contain imagery
libraries that contain much of the imagery needed to support strike mission planning. Operational experience indicates that the supplementary imagery needed to support mission planning can be transmitted in a timely fashion through the use of existing long haul data links.
One may imagine future Tomahawk strikes that involve the release of 1,000 rather than 100 weapons within a day. Such strikes would require either data transfer rates that are 10 times current rates or distributed databases that are significantly larger than the imagery libraries currently available on forward-deployed platforms.
Increasing the size of deployed imagery libraries would appear to be perfectly compatible with both existing and projected data storage technology.
D.220.127.116.11 Fixed-area Targets
Targets in this category are usually attacked with weapons carrying submunitions dispensing warheads. Weapons used for attacks upon distributed targets include ATACMS, JSOW, ERGM, and, if procured by the Air Force, JASSM. These weapons transport different size payloads of submunitions. Thus their lethal footprint varies from a few hundred meters for ATACMS to a few tens of meters for ERGM.
The information support needed for weapons in this class is relatively modest. The weapons generally have GPS/INS guidance, and target location errors of a few tens of meters can be tolerated. Thus, only modest amounts of data need to be provided prior to release of weapons in this class. The situation may change if GPS jamming forces a change in the guidance system to terrain-aided navigation. In such circumstances, the data transfer problem would be comparable to the data transfer problem needed to support the planning of a large Tomahawk strike.
D.18.104.22.168 Nonfixed Targets
Nonfixed targets are grouped by the committee into three subclasses designated as relocatable, ephemeral, and moving. This distinction is made because these three classes of targets tend to tolerate rather different levels of latency in the information networks that support their launch.
D.22.214.171.124 Relocatable Targets
That class of targets that may be moved at the adversary’s discretion is designated as relocatable targets. Targets in this category include, for example, tanks, trucks, armored vehicles, and missile batteries. Although targets in this category often remain in a single location for extended periods of time, they are difficult to attack on the same basis as is used in an ATO cycle devoted to attacks on stationary targets. Reports from both Operation Desert Fox and the Kosovo
campaign indicate that each adversary, knowing the ATO cycle time and the time of passage of imaging satellites or of unmanned aerial vehicles (UAVs), would relocate his assets by several hundred meters before the expected arrival of NATO strike weapons.
Unless a weapon delivery capability is co-located with, or is under the tactical command of, a sensor platform that is capable of redetecting relocated targets, the rate of success encountered when targets of this class are attacked with GPS/ INS-guided weapons will be low. A network that can cope with target relocation must be rather specialized. The ideal sensor platform for the detection of target relocation is the Joint Surveillance and Target Attack Radar System (JSTARS) whose moving-target indicator (MTI) radar detects moving targets provided that they are not masked by terrain obscuration or dense foliage. When the targets stop moving, they are no longer detectable by MTI radar. However, the location of the point where the radar lost contact with the moving target is the current target location. That point can be attacked if a weapon-equipped platform is within weapon range and has data links that allow it to be cued by JSTARS.
Weapons available to attack relocatable targets are well matched to their target set. They include JDAM, JSTARS, sensor-fused weapons, ERGM, HARM, and so on. These weapons should perform well provided that an appropriate tactical network is established that permits attacks on targets immediately after they have been located by a sensor system.
D.126.96.36.199 Ephemeral Targets
Ephemeral targets are normally hidden from detection by conventional sensors (radar, EO/IR, and signal intelligence) and are exposed to possible detection and attack for periods of a few minutes while they execute their mission. Examples might be the Iraqi “shoot-and-scoot” Scud missiles; North Korean artillery that emerges from a cave, fires a few rounds, and then retreats into concealment; or a guerrilla band that undertakes an attack and then disbands and becomes indistinguishable from the general population.
Currently, the U.S. Navy has no weapon sensor combination that can effectively engage an ephemeral target from any significant standoff range. Admittedly, if an ephemeral target emerges when an armed and ready F/A-18 is within weapon range, the target will have a high probability of being destroyed.
A component of the Navy (ONR) is working on a sensor weapon system based on the scenario of using a surveillance UAV that patrols an area where an ephemeral target is thought likely to emerge. Upon detection of a valid target, the UAV alerts a firing platform at sea and passes on the target’s coordinates. With no C2 delays, the remote platform is presumed to fire a supersonic weapon capable of traveling at an average Mach number of about 11.25. The weapon would arrive at the target (300 miles distant from the launch platform) within 2.5 min of initial target detection.
Obviously significant technological advances would need to be realized before such a scenario could be reduced to practice. In the interim, the Navy will probably opt for pragmatic solutions. Sensor platforms accompanied by well-armed weapon carriers will patrol areas that have high probabilities of hiding ephemeral targets. The weapon of choice will probably be something as modest as JDAM and the data link will be JTIDS.
D.188.8.131.52 Moving Targets
Targets in motion at the time of their detection by a remote sensor present a particular problem to a launch platform that attempts to attack them from beyond line of sight or long standoff distances. A subsonic weapon that is launched at a target from a 30 km distance might have a time of flight of about 1.5 min. During the weapon’s time of flight, a ground target moving at 40 km/h will have moved about 1 km. Under such circumstances, the probability of target kill will be low unless the target’s motion was compensated for by choice of aim point prior to weapon release or unless the weapon had a sensor and data link that allowed continuous update of its aim point.
D.184.108.40.206 Suppression of Enemy Air Defense
The weapons employed for the suppression of enemy air defense (SEAD) include the AGM-88, the high-speed anti-radiation missile, and a number of other air-to-surface missiles including the Hellfire missile used on the Apache Helicopter, the AGM-65 Maverick, the JSOW, and the JDAM.
Employment of these weapons for SEAD operations requires network support. HARM homes on the radar signals used to guide enemy air defense missiles, has a relatively short kinematic range, and for best results must be provided with target location uncertainty of less than about 2 km. Radiating targets may be localized by EA-6B aircraft, theater electronic intelligence (ELINT) aircraft, or national sensors. If the HARM is launched by the same EA-6B that provided the localization of the radiating target, then the supporting network and weapon release command authority is contained within a single air frame.
A true information network is required when the aircraft that launches the HARM depends on off-board sensors mounted on remote aircraft or national assets. Hostile radars do not radiate continuously. Thus, if such a radar is geolocated by a sensor system that is remote from the HARM launch platform, the network latency must be extremely low so that the geolocation information can be passed to the weapon launch platform before the target radar has ceased to radiate.
Upgrades are being considered to increase the HARM weapons system’s propulsion range, improve its capability against radars that cease to radiate, and
increase its warhead lethality. Although these projected improvements will provide better overall weapon performance, they should not result in reduced requirements for network support. HARM will continue to need relatively accurate target geolocation information, and with increased kinematic range, it will be even less tolerant of network latency than it currently is.
Air-to-ground SEAD weapons that are used to attack nonradiating air defense weapons (antiair or small shoulder-fired infrared (IR) guided missiles) are completely dependent on information networks for knowledge of target location. Aircraft that launch air-to-ground missile (AGM)-type weapons generally do not have sensors that provide detection and localization of nonradiating camouflaged weapons with a high area sweep rate. To the extent that fixed, nonradiating, camouflaged targets can be detected by EO/IR or synthetic aperture radar (SAR) imaging sensors, aircraft or national sensors specifically configured for the purpose are usually tasked to perform the function. The information derived from such sensors is passed to a SEAD battle manager who assigns aircraft and weapons to specific targets. The committee notes in passing that no operational sensor can detect shoulder-fired missiles on a consistent basis. In Kosovo, keeping aircraft at sanctuary altitudes and standoff ranges that could not be reached by either antiair or shoulder-fired missiles solved the problem.
Evolutionary improvements are scheduled for all AGM-type missiles. As in the case of the HARM, these improvements will result in significant improvements in weapon performance, but they will not result in a reduction of network support requirements.
SEAD also includes the requirement to eliminate defensive enemy fighters through air-to-air combat or through their destruction while on the ground. Since air-to-air combat is a component of fleet air defense, it is discussed in the next section.
D.1.2 Theater Missile and Air Defense
Littoral warfighting produces many challenges for the theater missile and air defense (TMAD) component of naval warfare. Mission effectiveness and efficiency in use of TMAD weaponry require the following:
Common awareness of the operational situation,
Ability to effectively coordinate defensive measures, and
Capacity for defense in depth.
Defense in depth is accomplished by two primary methods. The first method is through deployment of missile defense units into a geographic arrangement that assures multiple opportunities to engage and re-engage threats. The second method is through deployment of weaponry with varying fly-out ranges from a central location. Capable planning tools are needed to support development of
doctrine and tactics and force laydown. Additionally a suitable array of sensor capabilities must be available to support timely detection, control, and engagement for both techniques of providing defense in depth.
This discussion begins with the innermost layer of defense in depth, ship self-defense, and works outward through the progressively longer-range layers.
D.1.2.1 Ship Self-Defense
The primary threat for shipboard self-defense systems is the antiship cruise missile. Challenging aspects of the evolving threat include lower target signatures in the radio frequency (RF) and infrared spectra, higher speeds, programmed and responsive maneuvers, onboard countermeasures, ability to conduct time-of-arrival control during raid attacks, and difficult-to-destroy payloads. These threats may be launched from aircraft, surface or submerged vessels, and land-based locations within the littoral environment.
The weapons for ship self-defense include the Close-In Weapons System (a closed-loop gun system) and short-range surface-to-air guided missiles such as the rolling airframe missile (RAM) (rocket-powered and guided by IR and passive RF). Both weapons are designed for short-range operations and require targeting to come from the defending ship. Off-board information will be used to support development of a composite target track suitable for cueing of local detection and tracking systems.
D.1.2.2 Area Air Defense
The primary threat for area air defense systems are the antiship cruise missile and the supporting systems such as launch platforms and countermeasures (e.g., standoff jamming). Challenging aspects of the evolving missile threat are the same as for ship self-defense. The added challenge is to avoid degradation in performance due to standoff countermeasures and raids.
The weapons for area defense include the family of standard missiles (rocket-powered and guided in terminal homing by semiactive RF and, on the IVA version, IR) and the evolved sea sparrow missile (ESSM) (rocket-powered and guided by active RF). These weapons are designed for longer-range fly-outs and could be supported with targeting from off board the firing ship. Off-board information will be used to support development of a composite target track suitable for cueing of local detection and tracking systems, management of sensor resources, and scheduling of engagements.
D.1.2.3 Air-to-Air Combat
Combat air patrols are established for the purpose of destroying enemy air-
craft before they can come close enough to the U.S. surface force to release their weapons.
Success is dependent on many factors including pilot training and tactics, aircraft agility and signature suppression, airborne sensors, support by early warning sensors on surveillance aircraft, the effectiveness of electronic countermeasures, and lastly the effectiveness of air-to-air weapons.
Modern concepts of air superiority are based on an integrated air defense network that provides information derived from sensors on airborne early-warning aircraft such as the E-2C or Airborne Warning and Control System (AWACS), to a battle manager who assigns targets to patrolling fighter aircraft. (Note that the battle manager is generally located on either the AWACS or the E2-C aircraft.) Cued fighter aircraft use their on-board sensors (radar and forward-looking infrared) to acquire hostile aircraft and launch their weapons. For air-to-air engagements, the concepts and doctrines of network-centric warfare are well established. Although the performance of existing network links has some limitations, air-to-air weapons are well supported by information networks.
Although the AIM-54 Phoenix weapon with a kinematic range of 150 km has been available for many years, because of restrictive rules of engagement, its use in combat has been rare. In recent years, the basic weapons for air-to-air engagements have been derivatives of the AIM-9 family of IR-guided missiles and the AIM-120 active radar-guided missiles. AIM-120 missiles currently have kinematic ranges on the order of 20 nautical miles (about 39 km). AIM-9 class missiles are reported to have kinematic ranges of about 10 km.
The overall thrust of the Navy and Air Force plan is to remain with existing AIM-9X and AIM-120 class missiles and to concentrate on pre-planned product improvements (P3I) in the areas of propulsion (kinematic range), off-boresight capability, hard-kill countermeasures, and integration into a network-centric model. The stated long-range goal is to neck down to a single, dual-range, air-to-air weapon that might be introduced about 2015.
In the continuum of air warfare, U.S. capabilities that include network support capabilities, AWACS and E2-C sensors, ELINT, National systems, aircraft performance, electronic warfare, and pilot training have given the United States an edge that has resulted in an enviable record in recent air combat.
In the area of seeker performance acquisition range and off-boresight performance are the critical performance parameters. U.S. air-to-air weapons hold advantages in ordnance lethality over those of other nations, and the P3I programs in this area are exciting, particularly with respect to accuracy and payload size. Missile size is important, particularly in stealth platforms with internal carriage requirements. If the missile cannot be accommodated internally in a stealth aircraft, much of the advantage of the stealth treatment may be lost.
The air-to-air weapons program is inherently designed to be evolutionary in nature. Performance improvements have been incremental but steady. The technology being used in the program is at the forefront of propulsion and warhead
technology. New and exciting leaps in technology are being realized. Current weapon performance is significantly better than it was 10 or 15 years ago. Although the goals of current weapon improvement programs such as a 25 percent increase in weapon range (for the same weapon volume) and a 15 percent increase in weapon velocity may seem relatively modest, they may well mean the difference between success and failure in air-to-air combat.
Air-to-air weapons are relatively mature in the sense that current weapon capabilities may be well up on the curve of realizable performance. As long as incremental performance improvements can be achieved at reasonable cost, support for such work is likely to continue. Although one may applaud the results achieved by a high-quality incremental program, one cannot escape wondering whether new approaches to air-to-air combat based on improved network capabilities should be explored.
As an example, success in a short-range air-to-air encounter depends among other things on how far off boresight an IR-guided weapon can be fired. This issue is being addressed with significant success. Nevertheless, if one asks what an incremental improvement in an off-boresight capability translates into in the time domain, the answer is generally about a few tenths of a second.
The dependence of future air superiority on such marginal incremental capabilities is not very reassuring. Clearly, until better concepts based on network-centric operations are developed, such incremental efforts should be continued. However, one would hope that the development of improved information networks, improved sensor resolution, and weapons will allow (even under restrictive rules of engagement) air targets to be engaged at much longer standoff ranges than current capability permits. Ultimately, with the potential advantages of network-centric operations, close-range air-to-air engagements should not be allowed to occur. The survival of U.S. aircraft should not be allowed to depend on a marginal enhancement in current off-boresight capability.
D.1.2.4 Land-attack Cruise Missile Defense
The primary threats for land-attack cruise missile defense (LACMD) systems are surface-target-strike cruise missiles. Challenging aspects of the evolving missile threat are the same as for ship self-defense.
The weapons for LACMD include the standard missile as well as aircraft-launched air-to-air missiles such as Sidewinder (rocket-powered and guided by IR) and the advanced medium-range air-to-air missile (AMRAAM) (rocket-powered and guided by active RF).
D.1.2.5 Tactical Ballistic Missile Defense
The primary threat for tactical ballistic missile defense (TBMD) is medium-to long-range tactical ballistic missiles, including conventional weapons as well
as weapons of mass destruction. Challenging aspects of the evolving threat include lower target signatures in the radio-frequency and infrared spectrums, higher speeds, programmed and responsive maneuvers, unintentional and intentional countermeasures, ability to conduct time-of-arrival control during raid attacks, and difficult-to-destroy payloads.
Shipboard weapons for TBMD include the Standard Missile-2 Block IVA (area tactical ballistic missile defense) and the Standard Missile-3 (theater-wide tactical ballistic missile defense). The SM-3 features a hit-to-kill exo-atmospheric interceptor with electro-optical guidance.
D.220.127.116.11 Primary Command and Information Support Requirements of Air Defense Weapons
As discussed above, mission effectiveness and efficiency in the use of theater missile and air defense weaponry require the following:
Common awareness of the operational situation,
Ability to effectively coordinate defensive measures, and
Capacity for defense in depth.
The committee discussed how to achieve defense in depth. Operational situational awareness is facilitated by gathering battlefield information from distributed sensors (in space, in the air, on land, or at sea). The content, accuracy, and latency of the information may vary widely. Additionally, information about portions of the theater or the threat may be quite sparse. The challenge is to develop a robust network of capabilities for gathering, processing, and disseminating the best possible information needed by the warfighters. Since warfighter needs do vary with time (e.g., planning versus real-time combat) and type of unit, the network must provide for flexibility in information access and display.
Coordinating defensive measures in a fully developed theater is needed to avoid ineffective and inefficient use of the limited number of guided missiles available, as well as to avoid incidents of friendly fire. A classic technique, in the absence of a distributed capability for fire control, is to divide the battlespace into regions or sectors. A combatant is assigned a portion of the battlespace; any threat entering the battlespace is to be engaged. This approach is generally slow to adapt to changes in availability of defensive units, provides little lead time to shooters, and retains significant inefficiencies.
The need exists for a dynamic system capable of the following:
Assessing sensor and weapon resource availability,
Determining probability of kill for each shooter,
Providing sufficient lead time and fire-control quality data to the preferred and next-in-line shooter,
Ensuring a means to command or determine that a shot has been taken against the designated threat missile, and
Accurately confirming threat missile kills.
The area air defense commander (AADC) system is being developed to meet these needs.
A single integrated air picture is a requirement for theater missile and air defense in order to accomplish the following:
Support planning and doctrine development, and
Permit effective real-time coordinated engagements (e.g., make weapon assignments, confirm engagements, issue re-engage orders).
Weapons in the theater-missile and air-defense mission require accurate fire control information in order to do the following:
“Gridlock” sensor-to-shooter coordinate and time-reference frames,
Discriminate threat from associated countermeasures and environments using multispectral and spatially separated sensors (including space-based sensors), and
Make real-time kill assessments and distribute that information for use in coordinated defense.
TMAD weapons require timely fire control information in order to do the following:
Maximize battlespace and defense in depth by providing fire-control quality data before the shooting ship is capable of detecting and engaging on a local target track;
With lower-quality data, permit cueing of local (or other) detection and tracking systems; and
Distribute target and engaging missile track data to permit effective coordinated engagements (up to and including forward-pass concepts).
The previously mentioned cooperative engagement capability is being developed to meet these needs.
D.1.3 Undersea Warfare
The weapons of undersea warfare are primarily torpedoes and mines. Navy emphasis in this warfare area at the moment is on defense, particularly to detect and counter sea mines. In the future, however, the submarine threat is expected to re-emerge as a high priority.
D.1.3.1 Mine Warfare
Sea mines are a class of weapon that has significant deterrent effects on submarine and surface-ship operation in areas where they have been deployed. In effect, they are weapons that have been programmed to detonate on recognition of the signature of specific targets. They respond to signatures detected by their organic sensors that have been subjected to the thresholds set by internal logic gates.
The U.S. Navy does not have an aggressive program for the introduction of new classes of sea mines. Improvements are programmed for sensor performance, signal processing, acoustic signature reduction, and resistance to sweeping and countermeasures. Although there are no plans to incorporate sea mines into a network-centric warfare concept, there are R&D programs working toward this objective.
D.1.3.2 Countermine Warfare
Expeditionary forces prefer to deal with mines by detecting and avoiding them. If covert detection is not required, airborne sensors can usually detect some classes of mines more rapidly than they can be neutralized. Sweeps, both mechanical and influence, detect as they neutralize, but their coverage rate is small.
Marine Corps doctrine calls for standoff forces that hold large stretches of coast at risk and then make rapid attacks before the enemy can reinforce the intended landing area. This doctrine requires that mine clearing be performed in stride and not alert the enemy of the intended landing area.
Among the weapons that are being developed to support in-stride clearing and breaching in very shallow water are large, rocket-deployed nets festooned with explosive charges. The charges clear a landing lane by detonating or displacing the mines.
D.1.3.3 Antisubmarine Warfare
Current undersea weapons include variants of the Mark-46 and Mark-48 torpedoes and sea mines. Although U.S. torpedoes can be used in an antisurface ship mode, they are primarily configured as antisubmarine warfare (ASW) weapons. Sea mines can be employed in either an ASW or in an antisurface ship mode.
Torpedoes are large and expensive weapons. Only a relatively small number are carried in ASW patrol aircraft or in submarines (where they compete with Tomahawk missiles for the available launch tubes). Thus they are not released unless a significant probability exists that a target submarine has been correctly
classified and has been localized to within the acquisition capabilities of the torpedo’s sensors and kinematic range.
As the radiated signatures of submarines decreases, and as stealth technology reduces their active sonar cross section, opportunities to use torpedoes will tend to decrease. Information networks that combine the output from multiple spatially separated sensors will become increasingly necessary to position a firing platform close enough to its target that a torpedo can be released and subsequently be guided to the victim submarine.
ASW has always been fought as a form of network-centric warfare. First, a database must be established that identifies the training, deployment, and maintenance cycles of an adversary’s submarines. Overhead imagery, communications interceptions, and human observers provide information concerning the submarine’s predeployment status. A submarine’s departure from port can be monitored by similar means. Its objective and likely area of deployment often can be inferred from the current political situation or from historical patrol patterns.
If an undersea surveillance system can provide occasional detections, and partial track information, then mobile reacquisition platforms (submarines and ASW aircraft) can be vectored to a projected point on the enemy submarine’s assumed track. Once in an area where there is a high probability of encountering an enemy submarine, local networks of passive and or active acoustic sensors supplemented by nonacoustic sensors, may be established to allow close enough localization of the target to allow release of a wire-guided torpedo. Some modern torpedoes contain high-frequency sonars that define the target structure with sufficient fidelity to allow aimpoint selection. Other torpedo sensors are based on wake homing. When a submarine launches a torpedo, information and guidance commands between the weapon and launch platform are transferred over a fiber-optic link. In the case of an air-launched torpedo, communications between the weapon and launch platform requires a fiber-optic umbilical between the torpedo and a surface buoy that is in radio contact with the airborne launch aircraft.
Although difficulties still exist, and not all platforms have full or continuous connectivity, the data links that are necessary to support a network-centric concept of ASW and torpedo usage exist. The most difficult links to operate are those to a deeply submerged submarine, to an air-launched torpedo, and to a networked tactical sensor field. The data rates for these links are typically no more than a few kilohertz. In the case of a submarine that cannot, for operational reasons, deploy a surface-piercing antenna, communications must be on a scheduled broadcast basis. Network broadcasts of this type have of course been employed almost since the beginning of submarine operations.
The U.S. Navy has no current funded program to introduce an entirely new torpedo. Current weapons will be subject to incremental improvements that will provide improved engines (better speed and range) improved on-board signal processing (enhanced resistance to countermeasures, improved target resolution and aimpoint selection), and increased stealth to avoid alerting the target before
the torpedo has closed to within a range that precludes escape by target maneuver. None of these foreseen or programmed improvements should stress the bandwidth or latency requirements of existing ASW networks.
The technology exists to develop an antitorpedo torpedo. Such devices are capable of traveling at speeds approaching 200 knots (about 370 km/h). If launched in a timely fashion, they could be used to save a ship or submarine from an incoming torpedo. The concept of operations would involve a closed network that employs an acoustic sensor to detect an incoming torpedo and a processing node that correctly classifies the torpedo and alerts a weapon-release control authority. Since minimum latency could be tolerated between detection and release of the antitorpedo torpedo, the system would need to operate in a largely autonomous mode. To date, no R&D program in support of this concept has been funded.
Although ASW sensors and tactics may be unique, ASW is an important warfare element of the tactical situation and is one of the battle group’s concurrent tasks. In contrast to the other warfare elements, ASW operations concentrate less on weapons delivery and more on detection and classification-situational awareness. Since ASW situational awareness will be derived from networked distributed sensors, ASW could again become an important beneficiary of network-centric technology.
The dramatic progress in threat quieting and the shift from blue water to the complex transitional littorals is driving the development of ASW initiatives toward active acoustics, nonacoustics, and network-centric concepts. Littoral ASW operations tend to be asset intensive, and battle group assets are required to operate in concurrent multiwarfare situations. The fundamental problem, both in blue water and littorals, is the loss of long-range continuous target tracking using platform-centric, legacy-sensor, and traditional operations. Today, operators are presented with short-range intermittent detection opportunities in a high-clutter environment, making classification difficult and dynamic. The response to this problem is to emphasize off-board sensors, distributed field processing, and network-centric information processing. A network-centric approach to ASW offers the potential for improved detection, classification, and asset allocation through sensor data fusion, collaborative analysis, and joint planning.
The battle group is required simultaneously to maintain the subsurface, surface, air, and land battle scenes while allocating assets in dynamic and shifting circumstances. The battle group must conduct ASW while conserving platforms and staffing for concurrent missions. Significant progress against the quiet littoral threat may result from recent advances in computing and communications technologies that support a network-centric approach to ASW. Generating a common tactical picture would make it possible for a target to be detected, classified, tracked, and engaged faster than currently is achievable with today’s platform-centric approach. Battle group elements would become part of a grid of sensors and processing stations. Their positions, search tactics, and sensor setup
could be optimized for sensor performance and environmental conditions. Clutter and false alarms could be resolved more readily through the use of a composite information base derived from all platform sensors over the course of operations. Target signature features across the whole search area could be evaluated to generate potential target tracks and a clutter map. Environmental drivers such as detailed bathymetry and sound propagation characteristics could be collected and analyzed to optimize the battle force ASW disposition. For all this to happen, it becomes necessary to provide an architecture that facilitates vertical and horizontal transfer of sensor information, a coherent tactical picture, hypothesis of intent, and assessment of potential options. The architecture would enable collaborative planning, multiple tactical decision aids, data fusion, advanced displays, and vulnerability assessments.
D.1.3.4 Primary Command and Information Support Requirements for Undersea Weapons
Information support for mining operations is more in the realm of intelligence and environmental support than tactical support. Situational awareness is needed to protect the mine-laying platform.
The most important information in support of countermine activity is the information that can be obtained about mine locations without revealing U.S. interest in the area. The use of covert mine reconnaissance from undersea platforms, aircraft, and space is generally intelligence preparation for littoral operations. Networked mine countermeasures will be important for situational awareness during amphibious operations.
Success in ASW is increasingly dependent on the ability to fuse seemingly disparate information and to reject false alarms from high-clutter littoral environments. Stealthy targets in these environments defy long-range continuous detection and tracking by legacy sensors. “Sniffs and whiffs” may accrue from different sensors on different platforms at different times, and revealing their common origin depends on network-centric fusion processing. In addition, contact fusion must extend beyond kinematic information alone. The summary of the target features derived from individual sensors can be shared, providing a more complete understanding of the target and enhancing the target classification process. The operational force must exploit environmental conditions, historic patterns, operational intelligence, event relationship, classification clues, and subjective evaluations. The operational success depends on being able to collect and share appropriate information across the force.
Common tactical decision aids and means for collaborative planning in this warfare area are required to provide the force commander with timely tactical interpretations, force planning, and tactical option reduction. Tactical decision aids should incorporate previous search results from all platforms and should help the force ASW commander resolve potential target contacts, given the limi-
tations on force assets, sensor performance, and requirements for continued search. The common tactical picture provides the scarce resource; real-time cueing by the stimulating platform will be needed.
D.2 SUMMARY OF NAVAL WEAPON SUPPORT NEEDS
This section summarizes information support requirements for weapons across all warfare areas, characterizing the needs in terms of accuracy of target location, data timeliness, and volume of data.
Several attributes characterize weapons and determine which weapons are appropriate for targets of interest. Weapon guidance type strongly influences the complexity and volume of information required for weapon employment. Weapon range and average speed establish the critical time span over which targeting information must remain current, whether it is provided at launch or updated in flight. Finally, either the weapon’s seeker field of regard or its warhead lethal radius determine the accuracy with which location of the target must be provided to the weapon. Other attributes of the target such as its hardness, size and shape, dwell time, and signature are important factors in making the appropriate weapon/target pairing. In addition, the target environment may have a strong impact on weapon selection. In urban warfare, for example, high priority may be placed on controlling collateral damage. The following paragraphs examine naval weapon and target attributes in appropriate combinations.
D.2.1 Weapon Guidance
There are four broad categories of weapon guidance: open loop, geodetic, closed loop, and ATR. Figure D.1 categorizes naval weapons expected to be in inventory circa 2010.
D.2.1.1 Open Loop
In open-loop guidance, a trajectory is imparted to the weapon that is calculated to cause it to hit its intended aim point. The weapon makes no in-flight corrections of any kind. Naval weapons in this category include ballistic artillery and gun rounds, rockets, bombs, and aircraft cannon. Engagement times (time of flight) of these weapons range from seconds to tens of seconds.
Geodetic weapons are programmed to be guided to a two- or three-dimensional coordinate in space and to dispense submunitions, detonate by contact fusing, or detonate by internally generated command. The weapon may maintain its geospatial reference through continual GPS updates. This category includes
many new weapons, e.g., JDAM, JSOW, ERGM, LASM, Tomahawk Block III (in certain modes), and others in the conceptual phase, e.g., the round for the advanced gun system and the advanced land-attack missile. Typical engagement times of these weapons span from tens of seconds through hundreds of seconds to about 2 h for Tomahawk.
D.2.1.3 Closed Loop
Weapons with closed-loop guidance usually have some form of seeker on board. Its implementation may either be self-contained or retain a person in the loop via a data link. Weapons in this category include the Mark-48 torpedo; many strike weapons such as SLAM-ER, HARM, laser-guided bombs, Maverick, and Hellfire; and antiair weapons such as the SM-2, ESSM, RAM, AIM-120, and AIM-9. Engagement times are normally tens of seconds to several minutes. A few weapon systems employ closed-loop guidance without a seeker. For example, the close-in weapon system (CIWS) shipboard radar measures projectile miss distance and corrects the gun’s aim. The projectile’s time of flight can be a fraction of a second to several seconds. As another example, Tomahawk’s digital scene matching area correlation (DSMAC) is not a seeker (it never “sees” the target), and yet the navigation corrections it provides and the use of a relative coordinate system to guide to the target location qualifies it as a closed-loop system. The future addition of a data link to the Tomahawk will permit providing target updates to the weapon, in effect providing closed-loop guidance.
D.2.1.4 Automatic Target Recognition
Automatic target recognition is an extension of closed-loop guidance wherein the seeker is capable of recognizing an intended target among false contacts. That is, the seeker can automatically recognize and reject objects protected by rules of engagement. The Navy currently has no weapons in its inventory capable of ATR.
D.2.2 Acceptable Time Late
Tolerable latency of targeting data varies significantly with the dwell time or speed of the target, as shown in Figure D.2. Data supporting the targeting of fixed targets (both area and structure) may be days, months, or years old. However, current identification must be provided, as was illustrated in the recent NATO bombing of the Chinese embassy in Belgrade. Relocatable targets require more timely targeting, varying from hours to minutes, depending on the mobility of the target. For example, an attack against complex surface-to-air missile sites or tent encampments may be successful with data hours old, whereas counter-battery attacks against missile launchers may require targeting-quality data available to an appropriate weapon system in minutes. Weapons employed against airborne targets need targeting data no more than seconds or milliseconds old.
D.2.3 Volume of Data Required
Figure D.3 attempts to summarize the volume of data required to target individual naval weapons. Developed to measure stress on communication and data links in time of crisis, it considers the total number of bits required to transmit perishable information needed to target the weapon.
Operational drivers include the following:
In-flight updates on target location to some air defense weapons throughout flight (SM-2, AIM-120, and ESSM);
Imagery transmitted from surveillance sensor to image-processing station for identification of a target and precise extraction of its geographic coordinates. The committee assumes this is the principal method of targeting the JDAM, JSOW, LASM, ALAM, and Tomahawk (in GPS-only mode);
Imagery transmitted from surveillance sensor to image-processing station for identification of a target and rough extraction of its geographic coordinates and retransmission of the image to a mission rehearsal system. The committee assumes this is the principal method of targeting SLAM-ER and one of the methods used for targeting unguided bombs;
Seeker images transmitted to aircraft crews controlling SLAM-ER or Maverick;
Passing of geographic coordinates from on-scene forward observers to naval fire control systems and on to weapon-launch platforms (ERGM, AGS, artillery, guns);
Passing of geographic coordinates from ground controller to close support aircraft (rockets, bombs, cannon);
Imagery transmitted from surveillance sensor to image-processing station for identification of target, creation of image references to be loaded onto the weapon prior to launch, and precise extraction of the relative coordinates between scene centers and targets (Tomahawk in DSMAC mode); and
Transmission of Tomahawk missions from planning center to launch platforms.
Figure D.3 does not include data already generally available (e.g., weather data) or nonperishable data (e.g., terrain elevation data that may nevertheless be vital to the mission).
D.2.4 Acceptable Target Location Error
Guided weapons are normally provided with an aim point. For many reasons, the aim point may be imprecisely located or defined. Targets that are selected from well-registered imagery may be geolocated to within a meter or less. Targets that are located by signal intelligence (SIGINT) or radar bearings may be located within an error ellipse whose longest axis might be 1 or 2 km. Moving targets must be tracked continuously by a sensor in order to provide a weapon with a target location.
The maximum allowable target location error (TLE) will depend on the warhead of the weapon used, the guidance system, and the nature of the target.
Figure D.4 displays permissible TLE for naval weapons. As a weapon that homes on a radiating signal, HARM can operate successfully with a TLE as great as 1 km. Its probability of target destruction is much higher if the weapon is launched in a target-range-known mode than if it is launched in a target-range-unknown mode.
The TLE for fixed area targets varies with warhead size and with the number of rounds that will be fired at a given area. A weapon such as ERGM that has a relatively small warhead is most effective if the TLE is 20 m or less. A weapon with a large warhead such as ATACMS, which has a lethal diameter of 200 m, can be effective even if the TLE is 100 m.
Air-to-ground weapons with unitary warheads generally are most effective if the TLE is less than 10 m. Air-to-air and air defense weapons that operate under closed-loop guidance can be effective even if their initial TLE was between 100 and 1,000 m. On the other hand, a weapon such as CIWS will be ineffective if the TLE exceeds 1 m or so.