Report of the APS Advisory Committee for Technical Studies on National Missile Defense
December 20, 2000
Committee Members: John F. Ahearne, W. R. Frazer, Steve Koonin, Frederick K. Lamb (Chair), Kumar C. Patel, Roberta P. Saxon, Jeremiah D. Sullivan
Officio Members: James S. Langer, George H. Trilling, Judy Franz
A. Questions addressed by the Advisory Committee
The APS Advisory Committee on National Missile Defense was appointed by the President of the APS to consider whether the APS should initiate a study of aspects of national missile defense (NMD) and, if so, to assist in identifying possible leaders and members of a study group.
The Advisory Committee addressed the following questions:
- What is the current status of the U.S. NMD program and what are the key technologies and technical issues?
- Are there important technical issues that would be appropriate for the APS to study?
- If there are important technical issues that would be appropriate for an APS study, should the APS conduct a study now?
- If so, which issues should be considered by the study?
- If the APS conducts a study, should it be classified, unclassified, or mixed?
- If the APS conducts a study, who would be appropriate leaders and members of the study group?
In addressing these questions, the Advisory Committee consulted widely and deliberated carefully before formulating its recommendations.
B. Advisory Committee recommendations and explanations
The Advisory Committee unanimously makes the following recommendations:
1. The APS should initiate as soon as possible a study of several key technical issues related to proposed NMD systems.
After reviewing the status of current and proposed missile defense programs and technologies, the Advisory Committee concluded that (a) there are important technical issues that can be meaningfully and appropriately addressed by an APS study of NMD and (b) the results of such a study could have a significant impact, by making an important contribution to the nation's understanding of these issues and affecting upcoming decisions concerning NMD. The Committee therefore recommends strongly that the APS initiate such a study as soon as possible.
The Committee also recommends that the APS conduct a series of follow-on studies (see below).
2. The APS studies of national missile defense should address technical issues that have a substantial physics content and should be rigorous and objective.
The APS has a reputation for careful and objective technical studies. Its studies therefore have very high credibility and have had a large impact. The APS studies of NMD should continue this approach. The Advisory Committee believes there are important technical issues related to NMD technologies and systems that have a large physics component and are therefore appropriate for study by the APS.
3. The initial APS study of NMD issues should focus on several important technical questions related to boost-phase intercept technologies and systems for national missile defense.
The Advisory Committee considered the full range of technical issues related to NMD technologies and systems that would be appropriate for an APS study and concluded that the best course would be for the APS to begin with a study focused on technical issues related to boost-phase intercept. There were several reasons for this decision:
(a) There are significant questions related to boost-phase intercept where careful and rigorous application of basic physical principles seems likely to lead to important conclusions. An APS study of these questions is therefore opportune and appropriate.
(b) Proposals for boost-phase-intercept NMD systems are under active consideration and are currently receiving widespread attention.
(c) The Committee believes it is important for the APS to complete an initial study of NMD in a very timely fashion, for the reasons discussed in point 4 below. In order to achieve this goal, the scope of the initial study must be fairly limited.
(d) Technical issues relating to boost-phase-intercept technologies and systems have received much less attention and scrutiny than technical issues relating to the current NMD program, which relies on mid-course intercept. An APS study of boost-phase intercept is therefore likely to have a more immediate and substantial impact than would a study of the current NMD program, which has already received considerable public scrutiny and is now being further critiqued.
The specific boost-phase technical issues that the Committee recommends studying are discussed below in Section C.
The Committee does believe that there are important technical questions concerning the current NMD architecture and program and mid-course intercept technologies and systems in general that are both very important and appropriate for study by the APS. Some of these questions have been the subject of recent studies by other groups and committees. The Committee expects the current mid-course intercept NMD program to be continued for at least several more years and therefore expects that these technical questions will remain relevant. The Committee believes that a study of the current NMD architecture and program would be likely to have more impact in a year or two than it would at present. The Committee recommends that the APS consider a follow-on study to the initial study proposed here that would address some of the important technical questions concerning mid-course intercept technologies and systems.
4. Every effort should be made to complete the initial study within nine months.
Important decisions concerning NMD are likely to be made early in the next administration and will commit the U.S. for years to come. Therefore every effort should be made to complete the initial study within nine months, so that its results are available when these early decisions are made.
5. The proposed study of boost-phase intercept should be unclassified.
Initially a large majority of the Advisory Committee believed that any APS study should be classified. However, after carefully considering the current situation and the pros and cons, the Committee unanimously concluded that an unclassified study could address the technical issues listed in Section C in a highly credible and meaningful way and is the only viable approach. The principal reasons for this conclusion are:
(a) There is a wealth of information in the open literature about the technologies and systems relevant to boost-phase intercept. Important technical issues can be addressed using basic physical principles. An unclassified study of these issues would therefore be meaningful and credible.
(b) Waiting for decisions concerning access and cooperation would delay the start of the study by many months, especially because the U.S. is in the midst of a difficult and possibly contentious transition between administrations. Such a delay would significantly diminish the value and impact of the study.
(c) Conducting a classified study does not guarantee access to all or even most of the relevant classified information. Some relevant agencies and individuals may not cooperate and may later charge that important classified information was not considered. After careful investigation and consultation with various officials and individuals, the Committee concluded that an APS study of NMD might not receive cooperation from the relevant individuals and agencies.
(d) Considering classified information would mean that the results of the study could not be released until it has been reviewed by all the relevant agencies. This would certainly delay release of the report by several months and could delay it much longer, greatly diminishing its value and impact.
(e) Conducting a classified study would significantly constrain the pool of individuals available to serve as members of the study group.
(f) Although the conclusions of an unclassified study can be criticized as being based on incomplete information, the Committee believes that an unclassified APS study of boost-phase intercept would have a very high degree of credibility because many of the most important issues can be addressed using basic physical principles and because of the very strong reputation the APS has for conducting careful, objective, and rigorous studies of technical issues.
The Advisory Committee therefore concluded that the proposed study of boost-phase intercept technologies should be unclassified. The study group should include a number of scientists who have knowledge and experience in the relevant military programs.
6. The study group should be given some flexibility in deciding which specific technical issues to pursue.
Although the Advisory Committee believes that the technical issues identified in Section C are important and appropriate for the proposed study, the technical and policy context of the study could change and the study group may find that some issues are more or less suitable for detailed study. The Advisory Committee therefore recommends that the study group be given some latitude in deciding which specific issues to consider in depth.
7. A liaison committee should be created to facilitate communications between the Society and the NMD study group. A committee of knowledgeable APS members should review the report of the study group.
The Advisory Committee recommends that APS appoint a few members of the Executive Board and a member of the Panel on Public Affairs to serve as a liaison committee to facilitate communications between the Society and the study group and to serve as a sounding board for the study group as it makes decisions concerning the direction and timing of the study.
As with past APS studies, the report of the boost-phase-intercept study group should be reviewed by a committee appointed by the APS, before it is released.
8. APS should conduct a series of NMD studies over the next few years.
In addition to technical issues related to boost-phase intercept technologies and systems, the Advisory Committee identified several other important technical issues that could be meaningfully studied by an APS study group. Issues relating to the currently proposed mid-course NMD system have already been mentioned. Other issues identified by the Committee include certain testing and evaluation questions. Some of these issues are listed in the Appendix.
The Advisory Committee did not recommend that the initial study consider these important issues only because of the need to keep the scope of the initial study limited in order to make it manageable and timely. The Committee believes it is very important for the Society to address these issues over time, in order to provide the public and policy makers with a more balanced and comprehensive understanding of the overall situation.
Many institutions and organizations that have sought to provide useful technical input to policy decisions have found that comprehensive, long-term studies of major and complex technical question frequently have a disappointingly limited impact, because the decisions to which they are relevant have already been made by the time the study is complete. The Advisory Committee believes that this problem can be mitigated by conducting a series of shorter, more focused studies of related technical issues.
The Advisory Committee therefore recommends that the APS build on the proposed short-term study of boost-phase intercept to develop a new model for how APS addresses large and complex technical issues with important political and policy implications by initiating a series of studies of NMD technical issues over the next several years. These studies need not and probably could not be carried out by a single study group, but it may be helpful to draw on the experience of prior study groups and maintain continuity by having some members of earlier studies participate in the later ones. Some of these studies could be classified studies, if this approach seems important and workable at the time they are initiated.
Recommended focus of the initial study of NMD technical issues
1. The Advisory Committee recommends that the initial study focus on the following questions related to boost-phase intercept by hit-to-kill weapons:
1.1 Could one use existing radars or IR sensors to provide useful missile-track information to a boost-phase interceptor and kill vehicle (KV)? Are there other radar or IR sensor technologies that could provide useful missile-track information to a boost-phase interceptor and KV?
1.2 What are the constraints imposed on the sizes and weights of boost-phase interceptors and kill vehicles by the velocities and accelerations and geographic coverage needed to achieve intercept? What are the implications for basing modes and the ability to counter possible threats?
1.3 What is the phenomenology of missile plumes and what KV sensor capabilities would be needed to see the rocket exhaust and the hardbody through the expanded plume? Can existing sensor technologies provide these capabilities? Can other sensor technologies provide these capabilities? What kind of homing capabilities would be required?
1.4 Is it technically feasible to adapt the THAAD or Navy Theater-Wide TMD systems for a boost-phase intercept system?
1.5 What warning times are physically possible, what response times would be required, and what are the command and control implications?
2. The Advisory Committee recommends that the study group also summarize (perhaps in a separate chapter of their report) the current status of the Airborne Laser (ABL) program and the technical challenges involved in using airborne lasers for boost-phase intercept of ICBMs.
The technology of airborne lasers is significantly different from the technology of hit-to-kill weapons. Also, the ABL program is a very substantial program. Thorough study of the ABL program would therefore broaden the technological scope of the study significantly beyond the technology of hit-to-kill weapons, adding significantly to the task of the study group and requiring that it include many members with expertise in lasers and laser propagation. This would likely add substantially to the time required to complete the study. On the other hand, it is important that the APS not leave the proposed ABL system unaddressed.
It is the Committee's view that these difficulties can be largely avoided by including a summary of the current status of the ABL program and the technical challenges facing the use of airborne lasers for intercepting ICBMs in their boost-phase. Preparing such a summary would require only that several study group members have expertise in this area and would not increase substantially the task of the study group.
3. The Advisory Committee recommends that the report of the boost-phase intercept study group include a chapter that places its analysis of boost-phase intercept systems in context by summarizing the most important and challenging unresolved technical issues relevant to the current mid-course intercept NMD program, including testing and evaluation issues.
As discussed above, the Advisory Committee recommends that the current, mid-course intercept NMD system not be the main focus of the proposed initial APS study of NMD, in order to keep the study manageable and have a finished report in time to affect important decisions. However, it is important that the APS not leave the impression that these issues are resolved or unimportant, which could happen if there is no mention of them in the report of the boost-phase study group. There is precedent for mentioning technical issues relevant to related programs. The DEW Study Group report identified but did not discuss in detail important related issues, such as the role of kinetic energy weapons; command, control, communication, and intelligence; computing hardware; software creation and reliability for battle management; and overall system complexity. An appendix of the DEW report discussed systems integration issues.
The Advisory Committee recommends that the APS address more fully the important and challenging unresolved technical issues relating to the currently proposed mid-course intercept NMD technologies and systems, including testing and evaluation issues, in follow-on studies.
D. Suggestions for Study Group Leaders and Members
The Advisory Committee has compiled a list of qualified people who would be appropriate as leaders or members of the proposed study and has discussed this list with the APS President and President-elect.
Appendix: Recommended topics for follow-on studies of NMD
In addition to the technical issues related to boost-phase intercept technologies and systems cited above, the Advisory Committee identified numerous technical issues that are important and would be appropriate for study by the APS. The following list is intended to be illustrative rather than definitive.
1. The current mid-course intercept NMD program
Are there countermeasures to mid-course intercept that are likely to be effective against current and near-term intercept technologies?
Is it likely to be technologically feasible for a state that has developed ICBMs to deploy possibly successful countermeasures to mid-course intercept?
2. Testing and evaluation
Testing is generally restricted to two test ranges (White Sands and the Pacific Test Range), which means that the test conditions differ from operational conditions in many ways, including (but not limited to) the missile and interceptor trajectories, intercept geometries, relative velocities, altitudes, and day or night conditions. How important are these differences and how much uncertainty do they introduce in whether the system will work as planned?
How much extrapolation is required in going from tests to operational conditions? What impact does this have on the realism and adequacy of the tests?
How robust is the currently planned NMD system likely to be, given that (according to the Rumsfeld Commission Report) it will very probably encounter unexpected radar and IR signatures and countermeasures?
Given a certain effectiveness requirement, how many and what types of tests would be needed to determine with high confidence whether the system has achieved the required level of effectiveness? What uncertainties are introduced by possible countermeasures?
3. Airborne lasers for boost-phase intercept
The Advisory Committee believes there are many important physics questions related to the use of airborne lasers for boost-phase intercept that could be addressed by a more detailed study of this technology. Such a study could build on the analysis of boost-phase intercept using lasers contained in the 1987 report of the APS Study Group on Directed Energy Weapons, noting the technical problems with laser ABM weapons identified in the DEW study and describing the extent to which these problems have or have not been solved in the intervening period, in the context of airborne lasers.
A study of airborne lasers should probably focus on technical issues-- such as horizontal propagation of laser beams--that do not depend on the details of the laser itself.