Strategic Analysis

Strategic Analysis:
A Monthly Journal of the IDSA

April 2000 (Vol. XXIV No. 1)

 

A Failure Revisited: Closer Look at the Jan 2000 NMD Test
By Dean Mathew *

 

The Integrated Flight Test ( IFT 4 ) on January 18, 2000, of the US National Missile Defence (NMD) programme did not live up to the expectations of the Ballistic Missile Defence (BMD) community in the United States. The interceptor failed to 'kill' the attacking missile.

A modified Minuteman II missile launched from the Vanderberg Air Force Base(VAFB) in California towards the Marshal Islands in the Pacific, over a distance of 7,700 km, played the attacking Inter Continental Ballistic Missile(ICBM). An interceptor missile took off from the Kwajalein Missile Range(KMR) in the Marshal Islands about 20 minutes later, and attempted to engage the simulated warhead deployed by the ICBM. A Kinetic Kill Vehicle(KKV), released by the interceptor about two and a half minutes into the flight was to hit and 'kill' the warhead while it was still outside the atmosphere at an altitude of about 220km. The mock-warhead escaped, re-entered the atmosphere and splashed into the Pacific Ocean later. Referred to as the Integrated Flight Test No:4 (IFT 4), the January 18, 2000, episode was the first when major elements of the proposed NMD architecture were integrated into a real-time test. It was also the second attempt to actually intercept an ICBM-type target outside the earth's atmosphere.

 

Introduction

The National Missile Defence(NMD) programme, aimed at protecting the continental United States(CONTUS) from limited ICBM attacks, was launched in the year 1997 by the US Ballistic Missile Defence Organisation(BMDO). The system architecture and objectives were similar, in a limited way, to those considered in the Star Wars(SDI) programme. Cutting-edge technologies, some of them still nascent, were to play pivotal roles even at the 'feasibility demonstration' level of the programme.

With an unprecedented sense of urgency, the US administration asked the BMDO to prepare a Defence Readiness Review or Deployment Readiness Recommendation (DRR) by the summer of 2000. The US President's decision on the deployment of the system will be based on this recommendation and a re-assessment of the perceived threats.

 

The sense of urgency

The decision to initiate a DRR after a total of three tests has been totally unprecedented in US history. It is surprising that a country where it is mandatory for products of defence research to undergo a rigorous qualification process laid down by the 'Military Standards'(MILSTD), has actually decided to consider NMD deployment after two successes out of three tests. Moreover, only one of them needed to be a 'fully integrated systems test'. The official rationale for this urgency is that the perceived threat to the CONTUS from Weapons of Mass Destruction(WMD) is a reality that could happen sooner than later.

The perception clearly describes the threat as a 'limited' ICBM attack from one or more of the 'rogue' nations(say, Iran, Iraq, North Korea, Libya etc.) and 'non-national' actors like terrorist organisations, which are working hard to develop delivery systems (say, ballistic missiles) for nuclear, chemical and biological warheads. The threat is perceived as 'limited' in the sense that firstly, these entities will not have the wherewithal for mounting an all-out attack on the CONTUS and secondly, the level of technology that goes into building these missiles would be rather primitive vis-à-vis that of the US. In a broader definition of a 'limited' ICBM threat, a limited-scale accidental or unauthorised launch from Russia or China is also included. The current programme aims at the feasibility to defend against an 'unsophisticated'* attack of up to 20 warheads against the US.

 

The Programme

The NMD programme was laid down in 1997 on a '3 plus 3' schedule; an initial three years' window for development and tests leading up to a fully integrated system test during 1999-2000. In case a decision is taken to deploy the system after the tests in the year 2000, then the operational capability will be achieved in the following three years' window. Later, in an attempt to provide a reasonable incubation period for emerging technologies, it has been decided to stretch the second window to five years, effectively placing the programme on a '3 plus 5' schedule. 1

Though the formal launching of the NMD programme on a '3 plus 3' schedule was dated 1997, its genesis can be traced back to the first and second reviews (Jun/Jul, 1987 and Sept, 1987) of the SDI programme conducted by the Defence Acquisition Board of the US Secretary of Defence. As a fall-out of these reviews, a Phase I architecture was approved and six specific components of the SDI programme were cleared for further demonstration and evaluation. In this phase, the mission was to enhance deterrence against a Soviet first-strike and the planned defence involved thousands of interceptors based on ground as well as in space.

Meanwhile, there was considerable debate within the US calling for a realistic assessment of the SDI programme.* In 1989, the Bush administration decided to hold a review of the national security requirements and Ambassador Henry F. Cooper** was requested by the Secretary of Defence Richard Cheney to carry out an independent review of the SDI programme. Cooper submitted his report in March, 1990, and in it he spelt out the concept of refocusing the programme, which later came to be known as Global Protection Against Limited Strikes(GPALS). The GPALS was to protect the US, US forces overseas and its friends and allies against limited ballistic missile strikes. The concept involved hundreds of interceptors based on the ground as well as in space. The corner-stone of the concept was a path-breaking idea that later came to be known as Brilliant Pebbles.***

In January,1991, President Bush formally announced the reorientation of the SDI programme to the GPALS. 2

The break-up of the Soviet Union, the end of the cold war and the lessons from the 1991 Gulf War had influenced the reorientation of the US BMD efforts to a great extent. The end of the cold war and a much meeker Russia considerably reduced the threat of a massive, sophisticated ICBM attack on the US. On the other hand, the Gulf War drove home the reality of the threat posed by the theatre (short-range) ballistic missiles in the hands of Third World countries to the US forces and their allies on overseas campaigns. Moreover, the Gulf War and its consequences set the tone for future threats that could reach the US homeland by 'hostile' or 'irrational' entities with access to missile as well as Weapons of Mass Destruction(WMD) technologies. With this background, the BMD efforts were channelised into two distinct thrust areas viz. the Theatre Missile Defence (TMD)* and the National Missile Defence (NMD).

The Missile Defence Act of 1991, through subsequent amendments, paved the way for liberal funding of technology development activities through multi-institutional contracts during the next five years. The FY 1996 Defence Authorisation Bill called for the 'development for deployment' of an NMD system capable of defending the entire US. President Clinton vetoed this bill partly because of the 'deployment' clause which would have violated the ABM treaty. The Congress passed a new authorisation bill without the 'deployment' mandate, which received Presidential approval.**

In April, 1997, the BMDO established the Joint Programme Office(JPO) for the National Missile Defence programme after submitting the cost-benefit analysis report that was required by the FY1997 Defence Appropriation Conference Report. The JPO was to be responsible for the design, development and demonstration of an NMD system to defend the US from Ballistic Missile attacks, by the year 2003, which came to be known as the '3 plus3' NMD programme of the Clinton administration.

The DoD budget request for FY 2001 has $10.4 billion included through fiscal 2005 for the programme. If approved, the budget would allow DoD to upgrade the existing early warning facilities, provide 100 ground-based interceptors and fund additional testing.

 

The Architecture

The current NMD architecture has three principal components; 3

The Long-range Sensors acquire, track and identify the Re-entry Vehicles(RV) among debris and decoys, provide tracking information to the BMC3 and gather data to verify destruction of the RV. The Ground-Based Interceptors, capable of intercepting the RVs beyond the earth's atmosphere, receive and process the in-flight target updates, perform target selection and achieve target destruction. The BMC3 performs the integration of target warning and tracking data, preparation of engagement plans and the final battle execution.

Long-range Sensors

The long-range sensors in the NMD architecture include three types of target tracking sensors;

The UEWR is an upgrade of the existing, large, fixed, phased array early warning radar network. The primary role of these radars will be to track the targets during their mid-course phase,* mainly to cue** the more precise X-band radars.

The XBRs are X-band radars, stationed in the US and/or forward deployed, designed to acquire the incoming warheads, track them, distinguish them from decoys and assess whether they have been destroyed, after the engagement. They are configured to operate at sufficiently high frequencies and use advanced Digital Signal Processing (DSP) techniques to achieve better target resolution, superior to the existing levels. These radars are expected to perform more effectively against closely-spaced warheads, debris, and penetration aids. 4

The Space-Based Infra Red Satellite (SBIRS) system is a proposed network of early warning satellites in 'low' as well as 'high'(SBIR low and SBIR high) geo-synchronous orbits. This network will eventually replace the existing Defence Support Programme (DSP) satellites. Both SBIR and DSP satellites use Infra Red (IR) sensors to detect and track ballistic missiles throughout their flight. Once in place, the SBIRS will provide the 'over the horizon' acquisition and tracking of ballistic missiles. These satellites will detect the missiles during the launch phase and will continue tracking them while simultaneously* gathering information on them.

Ground-Based Interceptors

The Ground-Based Interceptor(GBI) of the NMD consists of a rocket booster and an Exo-atmospheric Kill Vehicle (EKV). The task of the rocket booster is to take the EKV to an area, probably in outer space, where it can locate the incoming missile in mid-course phase. Once separated from the rocket booster, the EKV will function autonomously. It will have its own set of sensors, propulsion, communications and guidance to undertake the interception. It is a 'Hit-to-Kill' concept wherein the destruction is achieved by physically smashing into the target at a very high speed. The enormous amount of kinetic energy transferred in such high-velocity collisions will practically atomise the physical matter involved, whatever their original form may have been. A hundred such interceptors are budgeted in the current programme.

Battle Management Command, Control and Communication (BMC3) System

The BMC3 is the 'nerve centre' of the NMD architecture. It holds the key to plan, co-ordinate, direct and control the weapons and sensors in near-real-time situation, across the globe.* It will be a ground-based set-up located in the CONTUS.

 

Integrated Flight Tests(IFT)

Considering that a majority of the technologies that may go into realising the NMD programme is better described as 'cutting-edge-level' and still evolving, the most logical way to build up the architecture is to integrate them incrementally. The approach, hence, will be to begin with assessing emerging element technology capabilities, followed by system technical performance and finally, the overall system maturity. Accordingly a series of Integrated Flight Tests (IFT) are planned under NMD, which are designed to;

IFT 1A and IFT 2 were to provide an assessement of the GBI sensor technology and performance, IFT 3 and IFT 4 were to evaluate the target discrimination and actual interception of RVs by EKVs and IFT 5 was identified as the initial integrated system test, evaluating the feasibility of the current NMD system performance. 5

These flight tests serve as an assessment of incremental system maturity. With the phased inclusion of various system components, as and when they become technologically feasible, the test structure will themselves evolve into comprehensive NMD integrated system tests.**

The Concept of Surrogation

It is interesting to learn how the BMDO used the idea of surrogation in structuring the Integrated Flight Tests to avoid the risk of rushing with nascent technologies. Except for the exo-atmospheric kill vehicle and its sensor package, surrogates have been used for all other major components, which are yet to mature, in the NMD architecture, during these tests. 6 True to the philosophy of IFTs, the level of surrogation was reduced progressively as and when the actual system prototypes became available. Optimum use of existing facilities like the Global Positioning System(GPS)* and the DSP satellites are two cases in point.

Integrated Flight Tests 1A & 2 ( IFT 1A & IFT 2)

The first two flight tests of the NMD programme were structured as 'fly-by' experiments to evaluate the performance of the sensor package developed for the EKV, simultaneously by two contractors Boeing and Raytheon. The principal objectives were to collect target signature data, to evaluate the sensor package performance as it would occur in the actual mid-course engagement environment in space, validate the up-link communication with the BMC3 and evaluate the target discrimination algorithms.

During both tests, the target complex (the mock-warhead plus decoys) was launched aboard a specially configured Minuteman II from VAFB, towards KMR, over the Pacific. The EKV sensor payload was launched from KMR aboard a Payload Launch Vehicle(PLV, a general purpose booster rocket) which released the payload at a pre-determined point in space. The planned in-flight rendezvous with the target complex was achieved on both occasions.** The sensor payload flew by the target complex, achieving the mission objectives successfully. 7

The Raytheon EKV

The Exo-atmospheric Kill Vehicle(EKV) is the 'Weapon System' of the programme and infact, the most ambitious of all the developmental activities taking place within the NMD architecture.

It is a 'Hit to Kill' vehicle, nick-named Smart Rock, which is supposed to destroy the target by crashing into it at a very high speed (about 2,200 m/sec). A dedicated booster will deliver the EKV at a suitable point in space from where it will function autonomously. The EKV, a state-of-the-art product, will have an up-link transmission facility with BMC3, an onboard navigation and guidance package, a sensor package consisting of a high-performance telescope, two multi-wave-band IR focal plane arrays sensors, one visual sensor, a cryogenic cooling assembly to support the IR arrays, propulsion systems and onboard power supplies. The Inertial Measurement Unit ( IMU, incorporating a laser gyroscope), which is responsible for guiding the EKV to the vicinity of the target, is supplemented by a confirmation using 'stellar navigation'.*

The EKV will use its sensors to detect the target complex based on the preliminary data supplied to it , select the right target and guide itself to a direct , high-speed collision with it using onboard computers, guidance, control and propulsion systems.

Integrated Flight Test 3 (IFT 3)

The IFT 3 (October, 1999) was the first attempt to actually discriminate an RV among decoys, within a target complex, and destroy it. Also under evaluation was the kill vehicle's deployment and orientation, in space.

The attacking ICBM deployed a target complex consisting of a mock-warhead and a (metal coated) balloon into a ballistic trajectory. The interceptor took off about 20 minutes later and released an EKV at a pre-determined location. Within a few minutes, the EKV guided itself to the mock-warhead, destroying it.**

Integrated Flight Test 4 (IFT 4)

The IFT 4 was a landmark test in the NMD programme . It was structured as a real time exercise, more complex than the previous test (IFT 3), with much lesser levels of surrogation . For the first time a prototype of the BMC3 element was integrated into the architecture for the real-time management of the episode. Again, for the first time a prototype, ground-based XBR was tried out as the principal sensor for tracking the target ( keeping the GPS option as stand-by for contingencies). In the EKV, the field of view of the sensor telescope was double that of IFT 3.

At 9:19 pm, Eastern Time, on January 18, 2000, the ICBM (modified Minuteman II missile) took off from the VAFB. Later, the RV and a balloon were deployed in a ballistic trajectory as planned. The targeted area was the Marshal Islands in the Pacific at a distance of 7,700 km. The estimated total flight time was around 30 minutes . The missile was promptly detected by the DSP satellites which alerted the BMC3 at Colorado, and provided the computed trajectory parameters. The BMC3 alerted all the radars in the network and cued the prototype XBR in the Kwajalein island, Hawaii.

The early-warning radars on the US west coast picked up and tracked the missile all the way across the horizon. At about 20 minutes into the flight, the prototype XBR picked up the target complex as soon as it appeared on the horizon.

The data gathered by the early-warning radars and the XBR were provided to the BMC3 which cross-checked the data with GPS ( for confirmation ) and worked out an engagement plan. The plan was relayed to the BMC3 centre at Kwajalein Atoll and was uploaded into the GBI . The interceptor took off (all in less than a minute's time). The BMC3 continued receiving the target data from the XBR and the target update was provided to the interceptor at the designated time, while in flight.

The EKV was released at about two and a half minutes into the flight . At that point the target complex was almost 2,250 km away from the EKV . The EKV stabilised itself and attempted the first 'star shot'. The 'star shot' was successful and the EKV aligned itself accordingly. A little while later, it attempted a second 'star shot', which ran into trouble. It did not see the expected constellation straightaway. The EKV resorted to a detailed procedure (termed first step function) as per the algorithm, saw the constellation this time and aligned the orientation accordingly. By then it had reached the area where the target complex was expected.

The EKV opened its sensors in an attempt to search for the target complex. Apparently, it saw the mock-warhead and the balloon straightaway. It successfully discriminated the mock-warhead from the balloon, using the visual sensor, and prepared for the end game. At this point, the target was handed over to the IR sensors. The IR sensors (two of them) were to maintain the 'lock-on' on the target during the end game (which lasts for about six seconds ), till target destruction.

At this point, there was a 'black-out'. The 'six seconds' passed by quietly. Nothing happened at '29 minutes, 49 seconds' after the ICBM had taken off from VAFB ( which was the estimated moment of interception as per the engagement plan worked out by the BMC3) .

The mock-warhead escaped, re-entered the atmosphere and splashed into the ocean, tracked all the way till splash-down. The EKV continued the flight, re-entered the atmosphere, broke up and was burnt out on re-entry.

The news was made public on January 19, 2000 by an official press release by the DoD 8 . The media called the test a 'failure' as the target 'escaped' and termed the $100 million that went into staging the test as 'wasted'.

Quick Analysis

The test had seemed to work well, better than expected, at every stage till the last six seconds. All the new prototypes integrated into the architecture functioned exceedingly well. A quick analysis pointed at a probable failure of both IR sensors during the end game, in turn rendering the EKV virtually blind during those crucial moments. 9

 

The Failure Revisited

Objectively, the 'failed' IFT 4 had too many 'firsts' to its credit;

And it was the first time, admittedly, both the IR sensors failed during the end-game.

The probable reason for providing two identical IR sensors for the same job was to provide redundancy considering the critical nature of the job. But, if it is confirmed in the final analysis that both the units had failed, it will indicate a failure of some element common to both. It can be either the common cryogenic cooling assembly which is supposed to cool the sensitive IR elements or the power supply source. In hindsight, it appears as if the Raytheon engineers failed the very idea of redundancy by tying down IR units to a couple of common elements which, incidentally, were critical.

Grey Areas

The end game where the EKV tries to collide with the RV draws from the best of engineering technologies of the day, some of which are still nascent . When one tries to visualise, the dynamics of the game may prove to be more gripping than 'shooting a bullet with another bullet'!

The end game begins when the EKV is at about 40 km from the target. The target will be moving at a speed of about 4,400 m/s . The EKV will be doing a speed of about 2,200 m/s. Essentially, the feat attempted by the EKV is equivalent to 'passing' through an imaginary 50cm x 50cm x 50cm box moving through space at an incredible velocity of 4,400 m/sec. The accuracy demanded, in time as well as space, is unheard of in the known history of engineering technology. An execution error of a billionth of a second can make all the difference.

The first point in question is an algorithm or a 'guidance law' that can accomplish this kind of an interception, which has an incredible element of uncertainty. The likely candidate here must be a probable breakthrough in contemporary research in the field of modern guidance laws like the 'Optimal Control Guidance Law'.

Another challenging area is that of 'control engineering', which is responsible for converting solutions provided by the guidance law into physical responses that will continuously maintain the EKV on a collision course during the end game. Nothing short of rewriting electro-mechanical engineering text-books will make things possible in the given circumstances.

Till recently (till IFTs 1A, 2 & 3 to be precise), an effective discrimination of a warhead from other decoys, during the midcourse phase, was considered virtually impossible (The only solution thought of was to destroy all of them using a nuclear-tipped interceptor !). Travelling through a near-vacuum environment in space, the entire cloud will be moving at identical speeds. The near absence of atmosphere will render the thermal signatures almost indistinguishable. The physical appearances can be doctored to make the warheads and the decoys to look alike. The only way, probably, to discriminate will be by a very precise mapping of their surface reflectivity and absorption indices with respect to the ambient radiation. These indices can cause minute variations among the thermal signatures of the objects in a target complex, depending on the materials they are made of. Hence, the discrimination excercise will involve very precise visible and IR mapping, backed by a super-efficient algorithm for data processing. With abundant reservations aired about a likely 'stage-managed' discrimination during IFT 3 using an obviously bigger balloon, it may well turn out that the 'discrimination package' has not matured enough to handle a real-time situation, left to itself.

 

Conclusion

The most important factor which makes the NMD programme unique is that it is about the protection of the US cities and their population, which, in turn, makes the civilian targets equally or more important than military targets. In a military sense, it may be acceptable to lose military assets in case a defence fails, but it will be politically unimaginable, especially in the US, to risk millions of civilian lives. This alone explains the extreme demands on the technologies that are to go into the NMD in comparison to those in other current BMD programmes, including the varieties of TMD.

If one considers the level of technological demands that were placed on the IFT 4, and the objectives/lessons achieved/learned, the test has been more of a 'success' than a 'failure'. The $100 million has not gone down the drain. What happened till the last six seconds was no mean achievement. And, what did not happen during the last six seconds could well have been due to a simple oversight during the design stage. On the other hand, if the final analyses point at something other than the IR sensors, then the solution lies in the technological advances yet to happen or just around the corner.

Finally, the sad reality is that even a proven, effective NMD system will still leave the US vulnerable to attack by other means. The ICBMs are just one dimension. There are many more which can dodge the proposed National Missile Defence.

 

Epilogue

Since the inception of the SDI programme, the United States has spent almost $ 50 billion to develop a national missile defence system. The DoD budget request for FY 2001 has included another $ 10.4 billion through fiscal 2005 for the programme. This money will fund upgradation of existing early-warning facilities, building a new radar complex in Alaska, a hundred Ground-Based Interceptors and additional tests. Alaska is chosen because a set-up at the current ABM base at North Dakota will not be in a position to offer cover to Alaska. Moreover, the perceived ICBM threats are expected mainly over the western horizon. But, the US east coast will be pushed to the fringe of the 'umbrella' if it is based in Alaska.

The precise form the proposed NMD system will take is not clear yet, but indications are that some of the features envisaged will violate the ABM treaty in its present form.

 

Endnotes

Note *: Research Fellow, IDSA.  Back.

Note 1: US Department of Defence News Briefing, January 20, 1999.  Back.

Note 2: ".....I have directed that the Strategic Defence Initiative programme be refocused on providing protection from limited ballistic missile strikes, whatever their source. Let us pursue an SDI programme that can deal with any future threat to the United States, to our forces overseas and to our friends and allies....": President George Bush, quoted from the text of the State of the Union Address, January 29, 1991.  Back.

Note 3: BMDO Fact-sheet No.JN-99-07, "National Missile Defense Integrated Test Programme", March 1999, Ballistic Missile Defense Organisation, External Affairs, 7100 Defense, Pentagon, Washington DC.  Back.

Note 4: BMDO Fact-sheet No. JN-98-06, "Component Elements of the NMD System", March 1998, Ballistic Missile Defense Organisation, External Affairs, 7100 Defense, Pentagon, Washington DC.  Back.

Note 5: Ibid at 3 above.  Back.

Note 6: Ibid at 3 above.  Back.

Note 7: BMDO Fact-sheet No. JN-99-08, " Ground Based Interceptor Sensor Flight Tests ", March 1999, Ballistic Missile Defense Organisation,, External Affairs, 7100 Defense, Pentagon, Washington DC.  Back.

Note 8: US Department of Defense News Release No. 024 - 00, January 19, 2000, The Office of the Assistant Secretary of Defense (Public Affairs), Washington DC.  Back.

Note 9: US Department of Defense News Briefing , January 19, 2000, by the Office of the Assistant Secretary of Defense(Public Affairs), Washington DC.  Back.