Time-critical strike is certainly one of the most important components of modern warfare and accordingly warrants a significant investment of ONR's resources. The importance of time-critical strike is also reflected in the significant S&T investments in this area by the Air Force and by the Defense Advanced Research Projects Agency (DARPA). Some components of the Time Critical Strike Future Naval Capability (TCS FNC) program appear to be coordinated closely with parallel DARPA and Air Force programs. Other components represent efforts that are unique to naval requirements.
The integrated product team that provides guidance for the TCS FNC has identified many capability gaps and the enabling capabilities needed to defeat five classes of targets:
Expeditionary warfare targets with naval fires;
Relocatable targets at range;
Short-dwell mobile targets at range;
Moving targets at range; and
Active hard and deeply buried targets at range.
Because of resource limitations, the TCS FNC is not scoped to try to eliminate all of the gaps in the capabilities needed to defeat the five classes of targets.
Many factors determine success in time-critical strike. In the sense that it is used in that term, “time” is the sum of the times needed for the following:
For identifying and geolocating a valid target;
For deciding to attack the target; and
For a weapon to travel from its launch point to its intended target.
The word “critical” refers to the fact that the sum of the times listed above must be less than the total
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program 4 Thrusts of the Time Critical Strike FNC Program OVERVIEW Time-critical strike is certainly one of the most important components of modern warfare and accordingly warrants a significant investment of ONR's resources. The importance of time-critical strike is also reflected in the significant S&T investments in this area by the Air Force and by the Defense Advanced Research Projects Agency (DARPA). Some components of the Time Critical Strike Future Naval Capability (TCS FNC) program appear to be coordinated closely with parallel DARPA and Air Force programs. Other components represent efforts that are unique to naval requirements. The integrated product team that provides guidance for the TCS FNC has identified many capability gaps and the enabling capabilities needed to defeat five classes of targets: Expeditionary warfare targets with naval fires; Relocatable targets at range; Short-dwell mobile targets at range; Moving targets at range; and Active hard and deeply buried targets at range. Because of resource limitations, the TCS FNC is not scoped to try to eliminate all of the gaps in the capabilities needed to defeat the five classes of targets. Many factors determine success in time-critical strike. In the sense that it is used in that term, “time” is the sum of the times needed for the following: For identifying and geolocating a valid target; For deciding to attack the target; and For a weapon to travel from its launch point to its intended target. The word “critical” refers to the fact that the sum of the times listed above must be less than the total
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program time that a mobile or relocatable target remains where it was projected to be located at the time of weapon launch. Thus, if the military leadership of an adversary is determined to be in a specific building, that building will be a critical target only as long as the group of interest remains within the targeted building. In the event that the target is in continuous motion, the time-critical strike problem converges to the moving-target problem. The word “strike” in this context refers to the capability of delivering a weapon of sufficient accuracy and lethality to destroy the target while it is still a valid target. Traditionally there have been two approaches to the time-critical strike problem. One has been to reduce the times needed to identify, geolocate, and decide to attack targets. When the target sensor and the weapon are on the same platform (as, for example, on a manned strike aircraft), the problem is somewhat less complex. If a pilot locates a target with onboard sensors or with the aid of a ground observer, and if the pilot's rules of engagement are satisfied, a weapon can be released. In such situations, the time-critical strike problem is simplified. A more difficult situation occurs when the sensor that detects the target is not colocated with the weapon release platform. In that case the decision-making process can be long compared with the dwell time of the time-critical strike target, and the time of flight of the weapon can be significant. The second approach is to reduce the weapon's time of flight to the target once it has been launched. There are two traditional ways to reduce weapon time of flight: (1) produce a weapon system (rockets or hypersonic weapons) that travels long distances at extremely high speeds and (2) develop loitering weapon delivery systems (uninhabited air vehicle (UAV)-borne or with sustained cruise capability) that can remain near a suspected critical target area for extended periods of time and attack the target from short ranges when commanded to do so. Given the ensemble of future military situations that may confront our forces, both approaches are important and should, to the extent permitted by budget constraints, be included in a TCS FNC program. The TCS FNC is comprised of eight separate thrusts, all of which relate to some individual aspect of the complex time-critical strike problem. Depending on the specifics of an individual conflict, the significance of these thrusts may vary from being highly significant to marginal. The TCS FNC thrusts are as follows: Cruise missile real-time retargeting; Image and video analysis; Enhanced target acquisition and location system; Precision strike navigation; Mission-responsive ordnance; High-speed antiradiation demonstration; Weapons imagery link; and Gun barrel erosion (and fatigue). Pursuant to the constraints of the FNC process and its budget, no attempt is made within the TCS FNC to find more global solutions to the overall problem of engaging time-critical targets by naval forces. Instead, the effort addresses about seven specific limitations of current systems. Among the longer components of the total time required for the time-critical strike process is the time required to locate and identify valid military targets with sufficient certainty to allow a military commander to authorize the release of a weapon to that target. The image and video analysis thrust addresses the problem of reducing the time required for target identification using electro-optical imagery produced by specific sensors such as the F/A-18 SHARP electro-optical system and/or by the synthetic aperture radar (SAR) imaging sensor on the Global Hawk and/or the Predator.
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program No other thrust is being supported under the TCS FNC that will result in sensors that allow more rapid and efficient target detection in difficult environments or sensors that will better discriminate between military and civilian targets or between military targets and decoys. The cruise missile real-time retargeting and mission-responsive ordnance thrusts may be interpreted as a limited approach to the development of a loitering weapon capability that would allow the rapid engagement of critical targets once they have been detected and authorized for attack. The main limitation of this approach is that the loiter time of a cruise missile such as the Tomahawk is probably limited to about an hour at most. Thus, these thrusts represent an important but fragmentary approach to development of the overall capabilities needed for successful true loitering weapons. In summary, unless the thrusts that are contained in the TCS FNC currently under way are rejected by the intended transition recipient, it is recommended that they should be pursued to completion. Looking to the future, the committee recommends that the current thrusts should be replaced by a more meaningful program that reflects Joint (Navy and Air Force) priorities for TCS such as in Chapter 2, “Responding to Operational Requirements” and “Recommended New Program Areas.” The committee's assessment of the eight thrust areas that make up the TCS FNC are provided in the next section. PROGRAMS REVIEWED Thrust 1: Cruise Missile Real-Time Retargeting Overview The objective of this program is to produce a capability that employs Tomahawk cruise missiles (submunition variants) against time-critical targets by leveraging LADAR seeker technology from the low-cost autonomous attack system weapon system. The evolving CONOPS assumes that a Tomahawk missile is launched against a primary target or makes a brief excursion to attack a new target and, in the future, will be placed into loiter. If a time-critical target were detected while the missile is in flight or in loiter position, target data would be sent to a strike cell coordinator, who would overlay the target data on a georegistered database. The Tomahawk would then be retargeted while in flight or in its loiter position. Two minutes before reaching the main target area, the missile would receive target update data. The Tomahawk's LADAR seeker would then be used to locate and identify the targets and to activate the Tomahawk's submunition dispenser. If the target is killed or hides prior to attack, the Tomahawk would be placed back in loiter (subject to fuel constraints). The key technical challenges identified in the development of this CONOPS are the following: Form, fit, and function for an eye-safe tactical Tomahawk seeker, Compact size, Low power, Thermal management, 200 g shock hardening, Low cost, Timely ATR processing of dense target areas, and Predictable and reliable performance of ATR, sensor manager, and search algorithm under conditions of target obscuration, confusers, and moderate clutter.
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program The technology demonstration program is divided into four build phases, with planned completion in FY05. Findings This thrust is proceeding in a well-organized manner with well-defined objectives and milestones. The perception of the committee is that the greatest area of risk relates to use of an automatic target recognition (ATR) algorithm that will be used to control the dispersal of submunitions. The committee is confident that the ATR algorithm will work well in situations where few confusing targets exist and where the probability of causing collateral damage is low. Unfortunately, there are many situations that do not meet these criteria or where the rules of engagement demand very high confidence that the ATR algorithm will not permit attacks on unintended targets. If total dependence on an ATR algorithm proves, in some situations, to be unacceptable to a local commander, alternative capabilities —e.g., the data link being developed under the weapons imagery link (WIL) thrust—should be explored for incorporation into this excellent weapon concept. WIL would allow the inclusion of man-in-the-loop capabilities to cover situations where the use of an ATR algorithm might not provide enough confidence in the ability to avoid collateral damage and satisfy rules of engagement constraints. Recommendations This program should be pursued as scheduled. More effort should be devoted to verifying the ATR algorithm that is selected for inclusion in the weapon. Provision should be made for eventually including the product of the WIL thrust if it is successful. Thrust 2: Image and Video Analysis Overview The objective of this program is to accelerate the exploitation of tactical imagery to improve targeting and battle damage indication capabilities against real-time-critical mobile targets. Sources of tactical imagery currently being addressed are the infrared/electro-optical sensor in the shared advanced reconnaissance pod (SHARP) carried by the F/A-18 aircraft and on the Global Hawk UAV SAR. The stated goals of the image and video analysis (IVA) thrust are as follows: Focus of attention subsystem (FOAS): provides automatic detection of relocatable targets in SHARP imagery; Automatic imagery registration subsystem (AIRS): automatic registration of tactical imagery to digital point position database (DPPDB); Automatic battle damage indication: automatic detection of indications of battle damage in SAR imagery; and Image compression: automatic compression of tactical imagery while maintaining target information. The IVA program is envisioned to provide integrated software capabilities that can be transitioned to the Joint Services Imagery Processing System-Navy (JSIPS-N) image exploitation system via soft-
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program ware modifications to the Tactical Imagery System and to the Precision Targeting Workstation in the 2006–2007 time frame. Findings The limitation of the FOAS of IVA is that available systems address only nonobscured targets when there is light clutter in the vicinity of the target. The goal is to develop new techniques that will achieve an 80 percent probability of detection with a false alarm rate of 0.01 per frame. The idea is to partition images into regions of uniform clutter and provide overlays that will process out the clutter in each such region. Known false targets will be eliminated on a detection map, and recent changes will be noted. The FOAS is designed to reduce the burden of work on a human image analyst. The objective of AIRS development is to achieve automatic registration of tactical imagery against national and digital point position databases. The goal is to achieve tie-point registration through a least-squares adjustment to referenced tie points. Work on battle damage detection and on image compression will not start until fiscal year 2005. The anticipated payoff of the IVA thrust is to improve the performance of JSIPS-N targeting for TCS against relocatable targets through the use of aided man-in-the loop image exploitation. The sense of the committee was that this problem was being approached somewhat in isolation and that it addressed only part of the chain. As was pointed out by the briefers, the problem has several parts, which can be described as follows. First is the correlation and fusion of area scenes from different sensors with different viewing angles, distances, different optical and RF spectrums, different resolution, and different display media. Second is the discrimination of potential objects of interest from normal terrain and vegetation, especially when camouflaged, based on unique signatures. Third is placing those objects in the context of the area to determine combat identification for a strike decision and, fourth, providing the strike mission plan and the data necessary for the shooter to approach, properly designate, and engage the target with the SHARP system as primary onboard sensor. Three observations are offered. First, multispectral sensing of the same scene is key to the target recognition and false alarm problem and should be exploited in the solutions being pursued. Second, high-speed, scene-to-scene correlation can often be best implemented using special-purpose, array-processing hardware and software. Third, the translation of one sensor platform's scene view to another sensor platform's view of the same area and their correlation and fusion and, later, the generation of a weapon lay down and shooter view can make use of modern commercially available terrain-rendering engines. These engines must be supplied with the GPS/inertial navigation information on each sensor platform and with the digital, theater-specific terrain databases that must be developed prior to theater entry. This process generates a rapidly adjustable “God's-eye” viewpoint to create common views by all sensors that can then be correlated. The committee noted that some excellent related work going on in the responsive targeting and precision guidance D&I thrust may help in the specific SHARP application being addressed here. Recommendations This effort should be pursued to completion following the present schedule. The work on battle damage detection should be accelerated. The USAF and the National Reconnaissance Office are sponsoring related efforts. Coordination with these related efforts should be established if it does not already exist.
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program Thrust 3: Enhanced Target Acquisition and Location System Overview The objective of this program is to improve target location accuracy and timeliness for the remote targeting systems used by Marine Corps forward observers and forward air controllers. The main source of setup time latency and target location inaccuracy is the current magnetic sensor used to provide target-bearing measurements. The enhanced target acquisition and location system (ETALS) will replace the magnetic sensor with a gyrocompass that has the following characteristics: Calibration time under 2 minutes; Azimuth accuracy to about 0.5 degrees (4.36 milliradians (mils); Weight under 2 lb; and Cost less than $7,500 in quantity. A secondary ETALS objective is to provide the capability for using the advanced eye-safe range-finder observation set (AEROS) to communicate digitally with the target handoff sensor, thus creating a seamless, low-cost daytime targeting system. The target location error (TLE) of the present operational system is driven primarily by the azimuth error, which provides a circular error probable (CEP) of 50 m at a range of 5 km. Improving the azimuth error to less than 5 mils will have diminishing returns, as current GPS position errors become the dominant error source. Unless differential GPS is employed, a 0 mil error azimuth determination system would have a TLE of 8.6 m regardless of range. Finding ETALS is progressing well toward transition to Program Manager Ground Weapons. Recommendation Continue the present program to transition. Thrust 4: Precision Strike Navigator Overview Missiles are normally guided to their intended target by an inertial measurement unit (IMU). The reference gyroscopes in the IMU drift. In an unjammed environment, GPS measurements are used to correct for the drift of the gyroscopes and ensure that the weapon is guided to its intended target. When GPS signals are jammed and the IMU drift cannot be removed, the weapon will miss its intended point of impact. For relatively short time-of-flight (TOF) weapons such as the joint direct-attack munition (JDAM) a low-drift-rate gyro will reduce or eliminate the need for a GPS update to offset gyroscopic drift. Thus a short TOF weapon with a low-drift-rate gyroscope would be immune to the effects of GPS jamming. Low-drift-rate gyroscopes are available, but their current costs are large compared to the cost of a
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program weapon such as JDAM. A low-cost, low-drift-rate gyroscope would greatly improve the performance of guided weapons that are potentially vulnerable to GPS jamming. The objective of this program is to demonstrate a high-level hybridization in the electro-optics of a low-cost fiber-optic gyro. The hybridization will allow for high accuracy IMU performance in a jamming environment at a price appropriate for tactical weapons. Specific program goals are as follows: Gyro bias stability of better than 0.02 degrees per hour, Projected unit production cost of $6,000 for a three-axis IMU, and Achievement of glide weapon CEP objective without the help of GPS. Findings If the goals of this program are achieved, the performance of short TOF weapons in the presence of GPS jamming will be made robust at an affordable cost. The initial prototypes produced under this thrust achieved the desired performance (less than 0.02 degree/hr). Unfortunately, they were not amenable to low-cost, high-rate production. Work is continuing on a design that can be produced at high rates of production and low cost. Recommendation Given the military importance of this program, this thrust should be pursued to a successful completion. Thrust 5: Mission Responsive Ordnance Overview The objective of the mission responsive ordnance (MRO) program is to develop and demonstrate ordnance technologies that will enable a single cruise missile payload to defeat unitary, area, and dispersed land targets. Implementation is planned in conjunction with the retargetable tactical Tomahawk (TT) cruise missile. The MRO payload is an integrated payload assembly constructed of multiple, guided, dispensable payloads termed kill vehicles (KVs). These KVs are distributed around an explosive-loaded integral charge (IC). The IC is packaged within the structure of the payload, providing the missile with a warhead when all KVs have been dispensed. The KVs are free-falling, fragmenting warheads, which are controlled by an independent guidance, navigation, and control system; thus they can be independently targeted through the two-way data link available on the TT. The IC that remains after the KVs have been dispensed is designed to be used against a default hard target. Findings As presented to the committee, work on the MRO thrust appears to have been initiated in the current fiscal year (FY02). The technology transfer plan was signed on April 2, 2002. Efforts to date seem to have been limited to planning and preliminary tests of warheads and KV dispenser concepts. Many concepts have been suggested for submunitions to be carried and dispersed by large cruise
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program missiles such as the TT. The area-attack version of the Tomahawk land-attack missile dispenses BLU-97 submunitions. These are effective against soft targets such as parked aircraft, vehicles, radar vans, and troops in the open. Other concepts postulate the use of multiple brilliant antitank (BAT) weapons. No evidence of analysis was presented to support the view that the payload being designed for inclusion in the TT was somehow optimized for many missions or that it offered more flexibility and tactical utility than other submunition concepts. Subject to the constraints of the volume and weight available within the cargo (warhead) section of the TT, many submunition configurations are possible. For example, submunitions to attack wide-area soft targets such as truck convoys, enemy air defense, and personnel could significantly enhance their lethality with a very capable miniaturized proximity fuze for each submunition. (The committee understands that some work is going on in this area by China Lake (California) under Naval Air Systems Command sponsorship.) This thrust is in its early stages. Even if further analytic effort shows that other submunition configurations are more advantageous than the one being considered, the technology being developed is important. As an example, the committee was impressed with the concept of submunition distribution in which the submunition initially penerates the missile wall. Recommendation Although the TT has only limited loiter capability, the committee regards its development with efficient submunitions as an important component of the TCS FNC and recommends that it be supported strongly. Thrust 6: High-Speed Antiradiation Demonstration Overview The basic antiradiation missile in current use by the Navy and Air Force is the AGM-88E. Although an excellent and effective missile, it does not incorporate new technology that has been developed since its introduction into service. In the high-speed antiradiation demonstration (HSAD) thrust supported under ONR's TCS FNC, an attempt will be made to demonstrate an improved booster that will incorporate the following: Nozzleless booster, Variable-flow ducted rocket, Tail-controlled steering, and Tail and throttle controlled autopilot. If the HASD is successful it will be incorporated into the design of the new high-speed antiradiation missile (HSARM), which will replace the AGM-88. The HSARM will provide increased standoff range, time-critical response, increased probability of target kill as a result of increased antiradiation homing accuracy, and increased terminal seeker accuracy. Because of its increased speed, range, and low-observable propulsion and steering (relative to the AGM-88E), the HSARM should be more effective than the AGM-88E for the mission of destruction of enemy air defense. The AGM-88 is largely used for suppression of enemy air defense.
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program Findings Although the objectives of this thrust are highly laudable, the technical challenges are daunting. Among them is the need to develop an integral rocket ramjet booster with no ejecta that will deliver a specific impulse greater than 200 sec along with a ducted rocket ramjet that can deliver a ramjet Isp greater than 850 sec. In addition, program success will require the development of a throttle valve with extended housing and plunger survivability. Operation times greater than 850 sec will be required along with a turndown ratio greater than 10:1 Performance of the vehicle-level propulsion system will be higher than that of any system yet tested in the U.S. technology base. Nevertheless the committee was encouraged by the good prognosis. The development of this advanced propulsion system is proceeding according to a well-laid-out plan. No technological showstoppers appear to have been encountered to date. This thrust is well integrated into the long-term development plans of PMA-252, the program manager for the AGM-88E, and it is coordinated with the efforts of the Air Force Research Laboratory Propulsion Directorate. Recommendation This program should be pursued until transition takes place and the development of the HSARM begins under PMA-242 sponsorship. Thrust 7: Weapons Imagery Link Overview An ability to control weapons in flight and to redirect them to an emergent target would greatly enhance the ability of naval and joint forces to execute time-critical strike. Such a capability requires a data link that is robust in the face of defensive jamming. The existence of a two-way link between the weapon launch platform and the weapon will permit weapons with imaging sensors to report-back potential targets in the field of view of the weapon's sensor. At a minimum, such a report-back capability will provide positive indications of the weapon's impact on its target and will greatly assist decisions on re-attack. At present the only available weapon imagery data link is the AWW-13, which is an analog link of limited capability. The objective of the weapons imagery link (WIL) program is to develop such a link for the standoff land-attack missile, expanded response (SLAM (ER)). This effort is tightly integrated into the ongoing development plans for PMA-258, the program manager for the SLAM (ER). Findings The approach being pursued in this thrust is to develop a time-division-multiple access (TDMA) link that will support 25 simultaneous transmissions to and from weapons. Antijam capability will be achieved through frequency hopping and short dwells. Data will be interleaved in many channels. As a result, many frequency channels can be totally jammed, but the data will be fully recovered. “Stacked nets” use different hopping patterns. Although hopping collisions can occur, their impact is handled by
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2002 Assessment of the Office of Naval Research's Air and Surface Weapons Technology Program forward error correction. The use of short dwells is designed to defeat intelligent jammers. The dwell time will be set to counter the response time of intelligent follower jammers in threat scenarios. The data link being designed in this thrust is a modern TDMA system that is somewhat reminiscent of LINK-16. The management of this link and processes for subscriber access will be complex but not intractable. In addition to the issues of link development, this program is addressing a number of associated hardware and software issues that are complex and present some degree of development risk. As the program is currently configured, it only addresses the development of a data link for the SLAM (ER). The installation of this data link onto other weapons would require specific hardware and software changes. The committee was disappointed to learn of the stovepipe nature of this development. Recommendations This thrust is tightly integrated into PMA-258's plans for the SLAM (ER) missile. The program should be supported to its scheduled transition, so that a high-performance modern replacement can be found for the AWW-13 data link. The committee recommends the development of an expanded CONOPS, including UCAVs or loitering platforms, for this data link. Thrust 8: Gun Barrel Erosion (and Fatigue) Findings Refractory materials and metal matrix composites and functionally graded materials that have been developed under Army and Navy SBIR programs, and Benét Laboratories/Watervliet Arsenal are working on key enabling technologies for this FNC program. The goal is to decrease erosion and increase fatigue life. This is a new program that is just getting under way. Two advanced barrel technologies (refractory and composite materials) are being developed concurrently. Experimental validation of designs is made difficult because full-scale testing of gun barrels is costly, and there are serious and challenging issues surrounding how one extrapolates and demonstrates fatigue life and erosion rates using scale models to simulate many cycles of gun firing. Recommendations A D&I activity to develop scaling laws for fatigue life and erosion rates should be undertaken that will permit small-scale model data to be extrapolated to full scale with confidence. Existing databases and expertise developed by the Air Force on fatigue of metal matrix composites should be utilized in deciding on appropriate materials. New processing techniques—e.g., explosive cladding—should be seriously considered for implementation, and integrated barrel designs that bring the materials and manufacturing processes should be given high priority.