National Missile Defense - Technological Issues Technical Overview Deployment Possible Countermeasures Software and Testing Technical Overview The proposed National Missile Defense system (NMD) is a land-based ballistic missile defense system with space-based sensors, designed to eliminate a small number (5 - 20) of ballistic missiles aimed at targets within the United States. It is composed of five parts: Ground-Based Interceptors (GBI):  The ground-based interceptor component of the NMD system is the part that actually destroys nuclear warheads. It is composed of a multistage booster rocket containing an Exoatmospheric Kill Vehicle (EKV). Upon obtaining a firing solution, the GBI is launched from the underground silo in which it is normally stored. Once the GBI has exited the atmosphere, the Exoatmospheric Kill Vehicle is released, and it uses its built-in thrusters to adjust its course as necessary to intercept the warhead. NMD Battle Management, Command, Control, and Communications (BM/C3):  The NMD BM/C3 component, which is essentially the "brains" of the entire system, is divided into two further parts: NMD Battle Management, Command and Control (BM/C2): This subelement controls the NMD system. Tracking information gathered by the NMD sensor net is transmitted to the BM/C2, which then processes the data and assigns targets to the GBI component. This subsystem is responsible for battle management decisions. NMD In-Flight InterceptorCommunications System (IFICS): This subelement is a distributed network of ground relay stations designed to facilitate communications between BM/C2 and launched GBIs. X-Band/Ground-Based Radars:  These sensor arrays begin tracking incoming ballistic missiles sometime during the mid-course phase. The targeting and trajectory information these radars provide are instrumental for GBI guidance. Upgraded Early Warning Radars (UEWR):  The ground-based portion of the missile early detection system, UEWR are phased- array surveillance radars that are designed to detect and characterize small targets near the horizon. Space-Based Infrared System satellites (SBIRS): The SBIRS satellites comprise the space-borne component of the missile early detection system, capable of detecting missile launches from anywhere in the world. The proposed concept of operation of the NMD system is summarized in this image. In essence, instead of a defense umbrella that focuses on destroying incoming ballistic missiles via spaceborne weapons platforms during all phases of missile flight, the NMD aims at elimination of ballistic missiles near the end of the mid-course phase. The flight of a ballistic missile can be divided into three phases. The first phase is the boost phase, which comprises the approximately 3-5 minutes right after the missile is launched. During this phase, any multiple independently-targeted re-entry vehicles (MIRVs) or decoys contained within the missile have not yet been released. The next phase is the post-boost or mid-course phase, which is the approximately 30-40 minutes the missile spends outside the atmosphere in transition to its target. At the beginning of the mid-course phase, any MIRVs or decoys are released, and forms what is known as the threat cloud. The last phase is the terminal phase, and is the last fifteen minutes during which the MIRVs and decoys re-enter the atmosphere on their way to the target. The purpose of the NMD system is to eliminate the MIRVs near the end of the mid-course phase but before re-entry into the atmosphere. If a ballistic missile is launched from anywhere inthe world, space-borne SBIRS satellites and early warning radars will immediately detect the launch and begin transmitting preliminary trajectory information to BM/C3. Somewhere during the mid-course phase, the X-band/ground-based radars lock onto the elements in the threat cloud, providing accurate targeting information for the ground-based interceptors. Near the end of the mid-course phase, GBIs are launched, and these interceptors will discriminate between legitimate warheads and decoys in the threat cloud, and destroy the warheads. Back to Table of Contents Deployment The deployment of the NMD system is divided into three phases. The first phase, Capability 1 (C1), must be capable of defense against the Threshold threat, as defined by the Capstone Requirements Document (CRD). This document is classified, but the Threshold threat is said to consist of an attack by five single-warhead ballistic missiles, with easily discriminated decoys and other countermeasures, such as chaff, flares, and jammers. C1 has an estimated deployment date of 2005. The second phase, Capability 2 (C2), must be capable of defending against fairly sophisticated payloads. The Threshold threat in this case consists of either a) five single-warhead ballistic missiles with a few (estimated four) decoys that cannot be discriminated (and thus must be destroyed), as well as other countermeasures, or b)twenty-five single-warhead ballistic missiles with simple decoys and other countermeasures. C2 has a deployment date of 2007. Capability 3 (C3), the third phase, must be able to defend against a) twenty single-warhead ballistic missiles with approximately five decoys that cannot be discriminated each, and other countermeasures, or b) fifty single-warhead missiles with simple decoys. This capability is to be fielded in 2010-2015. Back to Table of Contents Countermeasures "The simple fact is that we do not yet have the technology to field a national missile defense. We have, in fact, put some $40 billion into the program over the last 10 years. But today we do not technologically have a bullet that can hit a bullet." - Gen. Henry H. Shelton, Chairman of the Joint Chiefs of Staff, Sea Power Magazine,   February 1999. The technology behind NMD is not yet technologically proven. We have no reason to believe that in a realistic combat situation the system would perform its duty reliably. Indeed, numerous possible methods exist that would likely be able to either defeat or simply overwhelm the system. One simple technique would be to encase the warhead of a ballistic missile in a mylar balloon wrapped with aluminum foil. The foil would obscure the heat signature of the warhead, leaving the very large balloon as the only target for the interceptor. The planned NMD system uses a kinetic-kill technique, which means only a direct hit would disable a warhead. Since the warhead would occupy only a small fraction of the interior of the balloon, an interceptor would most likely pass harmlessly through the balloon and miss the warhead altogether. Moreover, a system could easily be designed such that after the balloon has been popped, another would immediately inflate around the warhead. This would make it substantially more difficult for an interceptor to destroy the warhead. (1) Numerous decoys could also be deployed to confuse the targeting system of the defense system. Though image analysis techniques have been improving, the task of discerning warheads from deliberately similar looking decoys is very difficult. Balloons and fake warheads could misguide many interceptors. Also, strategies are available to directly target the components of the national missile defense system. Detonating a nuclear device outside the Earth's atmosphere could create an electromagnetic pulse (EMP). Such an attack might be able to disable satellites and other electronic equipment involved in NMD. Russia already has many of these technologies. The Topol-M missile is already capable of releasing space-based "chaff" to confuse the NMD defenses and carrying multiple warheads (up to 6) to overwhelm the defenses. The missile also carries maneuverable warheads, capable of changing course after being released from the rocket in order to evade interceptors. Finally, the Topol-M has a shorter engine burn time designed to minimize launch detection. (1) Although the stated mission of NMD is not to defend against major nations like Russia or China, the existence of this technology means emerging military threats (North Korea, Iraq) may be able to easily produce them. A group chaired by Andew Sessler of the Lawrence Berkeley National Laboratory warns, "Any country capable of deploying a long-range missile would also be able to deploy countermeasures that would defeat the planned National Missile Defense system." (2) Also, Russia has not been in a very financially secure position during the last decade and may be persuaded to sell such technology to garner much needed revenue. Back to Table of Contents Software and Testing Issues "At present, we must conclude that SDI, given its complexity, lies beyond the limits of software engineering. And even if we could build such a system, the fact that we could not test it under realistic conditions would make it impossible to achieve the necessary level of confidence in its effectiveness." - Eric Roberts and Steve Berlin, "Computers and the Strategic Defense Initiative,"   Computers In Battle - Will They Work?, 1987. One of the primary reasons the original Strategic Defense Initiative project was not feasible was because the BM/C3 software that would be required to integrate the potentially thousands of space-based and ground-based sensors and weapons platforms could not possibly be rendered absolutely fault-free. Now that the concept of ballistic missile defense has been revived, the same question must be asked again. It is true that the current National Missile Defense project has less stringent criteria than the original SDI. Instead of having a large number of space-based and land-based defensive systems focused at shielding the United States from massive nuclear attack, the purpose of the NMD is to defend against fairly small numbers of ballistic missiles using a network of space and land based sensors and land-based interceptors. Theoretically, creation of BM/C3 software that would be capable of identifying nuclear warheads and destroying them should be possible. However, even if this software is written, the question of testing is uncertain. Testing was one of the major obstacles in the SDI program. There is no way to accurately simulate a massive ballistic missiles attack. With the reduced number of targets planned for the NMD, it might be possible for limited and fairly realistic test to be run on certain components of the system. However, as the recent Exoatmospheric Kill Vehicle tests have shown, ballistic missile interception technology is still far from feasible. it is not known whether the failures of the EKV were due to hardware of software problems. However, software behavior is inherently more difficult to characterize than hardware behavior, so even if the failures had been due to hardware, there are most certainly potential failures lurking in the software component. As an interesting side note, the simulation software for the NMD, which is being produced by Boeing, has been delayed by more than four months (3). Not only are there probably problems with the software itself, but there are even problems getting the software delivered. Since President Reagan introduced the Strategic Defense Initiative in 1983, seventeen interceptor tests have taken place. Of these tests only three have been considered successful. However, two of these so-called "successful" tests were later established to have been rigged. The only real successful test seems to be the one that took place in October of 1999, when an interceptor successfully destroyed a dummy warhead with only one decoy. However, the first test to operate with a partially integrated system took place in January of 2000 and failed due to the failure of the homing sensors on the EKV. There will only be one more test before President Clinton makes his deployment decision in June of 2000. (4) Back to Table of Contents *The technical information on this page was obtained from the Federation of American Scientists' Special Weapons Monitor page.