Precision guided munition

In modern war, the role of precision guided munition is increasingly being optimized by the military commanders to avoid collateral damages which helps overcoming the pitfall of public opinion as war causes lot of unwanted damages.

In fact, the evolution of new technologies has, in many ways, changed what defines a precision weapon.

For the first quarter of the 21st Century, the military commanders are looking not only for weapons that can hit a specific small target, but do so with variable levels of lethality; that can be redirected-or even terminated-in-flight; can be used in any environment, with or without GPS; and can use electronics to change the shape of an explosion, which also requires precise timing of the detonation.

Arising from historical antecedents in the First and Second World Wars, the specific technologies that made precision guidance a reality in the late 1960s were, nevertheless, the unique product of concerted actions taken within the US military, the federal government, and civilian industry.

Precision weapons did not emerge as a natural consequence of technological change, but were consciously constructed in response to the purposes, ethics, and values of American society.

Certainly the creation of important enabling technologies, notably lasers and semiconductor integrated circuits, played a decisive role in the development of these advanced weapons.

However, the emergence of guided weapons is inexplicable without also considering America’s evolving defence policy; the military doctrine that translated that policy into specific weapon systems and twentieth-century wartime demand, which stimulated research and development by providing added urgency, requirements, and resources.

Entering America’s arsenal at the height of cold war tensions, PGMs provided an appealing alternative to the largely impotent nuclear bombs and missiles that had become the centerpiece of US military strategy.

Post-Vietnam military operations highlighted a marked shift in emphasis away from mass destruction in favor of inflicting precise, controlled damage.

Reliance upon this technological innovation has produced a remarkable three-tiered revolutionary transformation in munitions technology, armed conflict, and US national security policy.

At the dawning of the twenty-first century, one thing humanity is not suffering from is a shortage of brave new technologies. The real challenge for the historian of technology lies not in finding a suitable subject, but in making sense of the exponentially expanding spectrum of technology that has inundated human existence.

Examining individual technological innovations may provide valuable historical insight, but only provided that one selects those particular technologies from which broader conclusions might be drawn.


In the selection of historical examples, military technology has long been neglected. In his 1990 analysis of trends within the discipline, noted historian of technology John Staudenmaier concluded that, despite its obvious influence on technical design and funding priorities for research and development, the relationship between technology and the military remains a relatively underdeveloped research area.

This unfortunate trend, not unlike a similar tendency among scholars ofAmerican history, perhaps stems from the erroneous conclusion that warfare and related military affairs have played a more or less uniform role in Western civilization, and can therefore justifiably be consigned to those specializing in military history.

The development and use of technology for military advantage is hardly unique to the American experience. Technology has shaped warfare in important ways since Herodotus first historicized armed conflict in the fifth century B.C.

In more recent centuries, such technological innovations as gunpowder, iron ships, and airplanes have played a decisive role in the development of Western warfare.

However, following the Industrial Revolution of the nineteenth century, the United States clearly developed a uniquely American way of war-one dependent upon a strategy of annihilation and the efficient employment of technology to defeat its enemies.

This unique way of war, built upon the strength of superior numbers and mass production, was epitomized by Ulysses S Grant in the final phase of the American Civil War.

And, while later military planners and leaders stuck with Grant’s overall strategy, they continually looked for ways to reduce the cost in lives, frequently turning to more and better technology as the antidote to decrease the bloodshed intrinsic to the strategy of annihilation.

While numerous specific technologies have been cited in conjunction with the ongoing revolutionary changes in warfare, the key elements of the revolution in military affairs have been reducing risks to friendly personnel and reducing diplomatically costly forms of collateral damage to enemies.

Therefore, if RMA has transformed the American way of war, as some have argued, there can be no doubt that precision guided munitions are the sine qua non of this new way of war.

In fact, it will be demonstrated that PGMs have proven revolutionary in a number of ways, bringing about what Thomas Kuhn would certainly have characterized as paradigm changes on at least three distinct levels.

In addition, because this study contends that PGMs have affected national security policy in significant ways, it will be useful to evaluate what they have achieved militarily, and whether or not American policymakers have perhaps overestimated what PGMs can accomplish for them strategically and politically.

Drawing such themes out of the story will, it is hoped, provide valuable insight into how people perceive and cope with technological change more generally.

Another underlying purpose of this study will be to shed light on the sources of technological innovation.

The resulting cold war policies of massive retaliation and flexible response rested upon radical new technologies, including ballistic missile guidance systems, but left American policymakers with few real options.

The relative neglect of military battlefield capabilities, and particularly accurate tactical bombing, left America ill-prepared to fight a conventional war, as became painfully obvious in Vietnam.

Review in RMA

An examination of the specific contributions made by participants within the military, government, and civilian industry further illuminates the process by which innovative military technologies are selected and created.

The use of precision guided munitions in the Vietnam War, and particularly the Linebacker air campaigns of 1972, marked a watershed in the application of modern air power. Thus, it is critical to an understanding of the long-term effects PGMs have had on military strategy and, consequently, national security policy.

During the final year of this conflict, newly acquired guidance technology allowed US forces to foil a major enemy offensive against South Vietnam without reversing the rapid troop draw down already well underway.

Clearly, this new technology created attractive new choices and options for American policymakers.

Crises and events in and around the Middle East, including the Arab-Israeli Wars, the US raid on Libya, and ultimately the Persian Gulf War, proved instrumental in fostering an ever-increasing demand for precision weapons.

Recent military operations by the United States have highlighted a dramatic shift in America’s use of the military instrument of power. An analysis of recent American military interventions throughout the past two decades seems to indicate that air power has become the defacto coercive arm of American national security policy.

In tracing the development of PGMs, from the rudimentary radio controlled weapons of the 1920s to the state of the art laser-guided munitions of the Vietnam era and beyond, it is clear that these weapons did not emerge simply as a natural consequence of technological change.

With the advent of PGMs, the US finally achieved its goal of a surgical strike capability and proceeded to incorporate it into its military strategy.

This dissertation will attempt to assess just how effectively the policies relying upon this technology have been in attaining America’s national security goals.

The level of precision available in 1991, while revolutionary, is several generations obsolete less than two decades later. But what is now being developed in military and industrial labs will make today’s PGMs seem even more crude by comparison, in less than a decade. Perhaps much sooner. In a progression from hitting a specific building to hitting a specific room, the next generation will, among other things, turn the foot soldier into a precision strike weapon, able to navigate without GPS thanks to a chip in his boot, and to fire guided bullets at targets like would-be snipers before they have a chance to fire at him.

Most PGMs today depend heavily on GPS for location and navigation, adding some advanced sensors for terminal target identification and guidance. Advances in inertial navigation systems (INS) also have added to the precision of weapons now deployed to Iraq and Afghanistan.

Future strategy

The future will be more focused on revolution than evolution, involving new technologies to enhance the precision of precision strike weapons.

Most of these efforts are still in research and development-especially at the Defense Advanced Research Projects Agency (DARPA)-with a significant number expected to leave the lab for fielding in the next decade.

A wide range of precision strike-related programs are scattered among several DARPA offices, such as Defense Sciences (DSO), Strategic Technology (STO), Microsystems Technology (MTO), Information Processing Techniques (IPTO). Some may share components or break- through technologies or ultimately may be combined to achieve a specific goal.

Precision Inertial Navigation Systems (PINS) is an effort to address the vulnerabilities of GPS navigation-jamming, spoofing, blind spots, etc.-by using ultra-cold atom interferometers to reduce the positional accuracy drift of INS by several magnitudes to achieve near-GPS accuracies.

Such a system could be used as a backup in case of GPS denial, or as an alternative to GPS on some platforms.

Basically, an atom interferometer takes a cloud of about 1 billion Cesium or Rubidium alkali atoms and cools them to a temperature one-millionth of a degree above absolute zero. Lasers then launch those atoms into an ultra-high vacuum enclosure, where their path is measured.

“We use one laser beam to split the cloud of atoms, making them behave like they are in two places at the same point in time. We then use another laser pulse to recombine those atoms and, in that process, are able to determine the interference between the two paths that cloud took,” said James Halnker, a leading arms expert.

“What happens during that time when the two atom waves are separated tells us about the inertial forces that have acted on those atoms. And that inertial force is what we are after in a navigation system.

“Our current challenge is to improve the sensor bandwidth to enable operations with a 10G input, so it is not only useful underwater, but will be a navigation technology available for aircraft and missile applications, as well. The predominant challenge is improving the sensor bandwidth, miniaturizing and integrating subsystems to enable that.”

EXtreme AC curacy Tasked Ordinance (EXACTO) uses a combination of a maneuverable bullet and a real-time guidance system to track the target and deliver the projectile to target.

Technology development includes the design and integration of aero-actuation controls, power sources, and sensors, according to DARPA.

The components must fit into the limited volume of a 50-caliber projectile and be designed to withstand a high acceleration environment. The EXACTO technology is planned for transition to the Army by 2012.

Based on a new 50 caliber BMG gun and improved scope, EXACTO would incorporate a variety of technologies, including fin-and spin-stabilized projectiles, internal or external aero-actuation control methods, projectile guidance technologies, tamper proofing, small stable power supplies, as well as advanced sighting, optical resolution, and clarity.

“DARPA’s goal is to remove the effect on accuracy of target motion and random variances in the environment through use of a guided bullet,” explains DARPA program manager Dr. Lyn Beamer (IPTO).

“Such variances cannot be accounted for in the initial aim point and include unknown winds, range-to-target, altitude differences between shooter and target, and round-to-round differences, among other factors.”

One benefit is that EXACTO no longer requires snipers to take several calibration shots to “walk” to the target for long-range shots or shots in adverse conditions, which avoids warning the target and risking their position.

EXACTO is mid-way through phase I, which will demonstrate all key components, concluding with a simulation tying hardware together in a software environment to evaluate system performance. Phase II will demonstrate a working prototype.

New programs

Counter-Sniper Program (C-Sniper)could be seen as the counter-weight to EXACTO, intended to detect and neutralize enemy snipers before they can engage US forces.

A primary objective is to deliver a field testable prototype as an integrated part of another DARPA program-Crosshairs.

Able to operate day and night from a moving vehicle, C-Sniper will provide data and controls to point and track an on-board weapon the human operator then can use to engage the target before the enemy can fire.

According to DARPA, challenges to designing a combat-capable system include detecting enemy snipers carrying weapons before they fire a shot by determining where the shot may come from; developing techniques to reject clutter; reducing system design complexity by keeping the number of moving parts to a minimum; and integrating C-Sniper with Crosshairs on military vehicles.

The purpose of the Crosshairs system is to detect enemy bullets, rocket-propelled grenades (RPGs), and mortars fired at US military vehicles, and then prevent them from striking the vehicle.

“Crosshairs is really a set of five capabilities, and it’s modular, so every vehicle may not have the full set,” says DARPA program manager Dr Karen Wood (STO).

“Crosshairs capability includes being able to answer the question, ‘What’s coming in at me? What’s the threat? And where is the shooter?’ The next capability is, ‘How do I respond?’ The third is controls and display-now I have a piece that tells me where in the scene the shooter or shooters are, so I can designate targets or improve my situational awareness.

“The fourth capability is networking. We use EPLARS (Enhanced Position Location and Reporting System) compatible radios, which are military standard, to network to the vehicles around me so they know there’s a shooter over here shooting this particular threat. The fifth capability is an active protection system. In Crosshairs, we’re using another DARPA technology called Iron Curtain, which defeats an incoming RPG round; we’re looking at some of the more advanced rounds right now, as well,” Wood says.

Micro inertial navigation technology (MINT)seeks to create high-precision navigation aiding sensors that directly measure intermediate inertial variables, such as velocity and distance, to mitigate the error growth encountered by integrating signals from accelerometers and gyroscopes alone.

The goal is to combine microscale inertial sensors and velocity sensors into an integrated circuit with very low power requirements, using energy harvesting technologies to replace batteries.

MINT would enable a variety of new applications, such as incorporating the sensor suite into the sole of a shoe for accurate and precise velocity sensing using zero velocity updating (ZUPTing) events while walking.

In a GPS-denied environment, such as urban canyons or thick jungle canopy, that could provide navigation accuracies equal to or exceeding GPS, even after several hours of walking.

Phase I has demonstrated an average position error of four meters at the end of a half-hour walk, which is several orders of magnitude better than the direct, uncompensated integration of inertial information.

Digital use

Position and orientation are expected to be projected on a digital map and perhaps shared with a squad.

“We also are exploring some new initiatives when self-calibration algorithms will be applied to sensors themselves, thus limiting the growth of error, and a new self-calibration paradigm and ZUPTing-on-a-chip, which is based on Earth magnetic field updates,” says program manager Dr Andrei Shkel (MTO). “Those potentially new developments will be directly applicable to terminal guidance and other non-ground navigation/guidance.”

A second DARPA goal is to combine inertial measurement units (IMUs) and velocity sensors for unmanned aerial vehicle (UAV) flight controls, enhancing the ability of several UAVs to navigate in close proximity while avoiding collisions.

“The focus is to develop a precision zero velocity event detection sensor and incorporate it with a chip-scale MEMS IMU. The information is processed by the Zero Velocity Update Algorithm, resetting the Kalman Filter estimator when a zero velocity event is detected (i.e., foot touching the ground),” Shkel says.

“Effectively, the performers are exploring several concepts for a personal micronavigation device that uses a high-resolution, gait-corrected IMU.”

Navigation-grade integrated micro gyroscopes (NGIMG)involves the development of tiny, low-power, rotation rate sensors that can provide navigational accuracy in GPS-denied environments for individual soldiers, micro-UAVs, unmanned underwater vehicles and even insect-sized robots.

With CSACs and location-tracking algorithms that harness additional kinetic information, chip-scale NGIMG’s should allow man-portable, dead-reckoning devices with unprecedented precision,with and without GPS.

DARPA believes the subsequent growth in applications also is expected to generate a need for high-volume manufacturing that, combined with wafer-level batch fabrication methods enabled by MEMS technology, should substantially lower the cost of miniature navigation systems and further fuel expansion NGIMG applications.

According to Shkel, who also is program manager for NGIMG and CSAC, among the enabling technologies required for NGIMG are chip-scale atomic precession, spin-stabilization of Rubidium and Cesium isotopes, duality of elastic waves and electrostatic levitation and high-speed spinning of micro-structures.

Chip-scale atomic clock program (CSAC) program is designed to create ultra-miniaturized, low-power atomic time and frequency reference units that will achieve, relative to present approaches, a 200X reduction in size and a 300X reduction in power consumption, with no loss in accuracy.

A projected application is a wristwatch-size, high-security UHF communicator and jam-resistant GPS receiver, but overall CSAC could drastically improve channel selectivity and density for all military communications.

It also will enable ultra-fast frequency hopping in synchronized spread-spectrum communication for improved security and jam resistance and strong encryption in data communication.

GPS introduction

In military GPS receivers, it will greatly improve the jamming margin in high-jamming environments, reacquisition capability, and position identification accuracy. In surveillance applications, CSACs can be used to improve resolution in Doppler radars and enhance accuracy of location identification of radio emitters.

Other uses include missile and munitions guidance, robust electronic and information defence networks, and high-confidence, friend-or-foe identification.

Shkel says stable atomic transitions between energy levels and laser cooling of atoms on a micro-scale are among the required enabling technologies for CSAC, which already has been selected by the Army for its Manufacturing Technology efforts and will be tested for performance in a weightless environment aboard the International Space Station in 2010.

In combination, CSAC and NGIMG offer “a self-contained position, orientation and timing solution on a single chip,” he adds. “It will not require any external signals and cannot be affected by weather, interference or deception by enemies.”

US Army, Air Force, and Navy labs and dozens of contractors, working both government-funded and internal development programs, also are pushing the state-of-the-art in precision.

One approach involves the use of Shortwave Infrared (SWIR) imaging sensors for terminal guidance systems. For example, Goodrich ISR Systems in Princeton, is developing two-dimensional photodiode arrays that are sensitive from about 900 to 1700 nanometers-the SWIR band-which contains the majority of wavelengths for laser sources.

“That can be a 1-micron target designator, a 1.5-micron eye-safe laser, etc.,” notes David G Dawes, Goodrich’s business development manager for US Department of Defense (DOD) applications.

“We also can extend that to shorter wavelengths, down to 700 nanometers, via a special process that gives us the ability to capture near-IR, most importantly the 850-nanometer laser pointers used by most weapons aiming sights.

“So an imaging sensor can see and confirm where designators are targeting; at present, most systems have a ‘point-and-pray’ mode of operation-praying they hit the right target. To get confirmation you are on target, you need to see the laser spot; our sensor is one of the few that can do that. It also could be used defensively, to determine if you are being lased for a missile launch.”

Lighter weight, ultra-sensitive imaging sensors also may enhance the capabilities of UAVs for intelligence, reconnaissance and surveillance (ISR) missions, enhance the targeting capabilities of weaponized UAVs or, eventually, become part of a PGM seeker.

“It’s all about discrimination and positive ID of targets, especially in an urban theater of operations. Having seekers that can discriminate and track targets with better precision is the direction we’re going-and imaging sensors are the key enablers for that effort,” Dawes says.

“And the key enablers for those sensors mean being able to see targets in all kinds of environments and weather conditions, with all the contextual clues you really need for good identification rather than just detection.

SWIR has advantages in having an intuitive visible light quality-the image it produces is similar to what you would get in the visible arena, based on reflected light.

“Thermal images are based on emitted light from objects themselves and you lose all the details of surface texture needed to really identify an object as a specific target. And, on top of all that, you have the ability to see lasers. All of this is in a compact 90g package, with smaller ones in development with higher resolution.”

Goodrich also is involved in a DARPA program called Dual-Detector Ensemble (DuDE), which uses a SWIR focal plane on which a microvelometer long-wave detector layer has been deposited.