The Controversy Over The APS Report
Given the highly charged political atmosphere surrounding SDI, it is not surprising that the manner in which the council presented the report stimulated some very strong reactions to the report itself. Fortunately, neither the president's science advisor nor the senior officials of SDIO confused the council's statements with the report itself. Although they clearly would have preferred a more optimistic tone, they accepted the report with reasonably good grace. Shortly after the report was issued, Louis C. Marquet, deputy director of SDIO for technology, declared in a press interview: "I think, frankly, that they carried this study out in a very responsible fashion. … I frankly think that both of us gave each other A's. … There was nothing in their report which says we're completely out of our minds, that something is beyond the laws of physics." A handful of the most fanatical advocates of the project had a different response. Ordinarily, the opinions of such a small group would not matter very much to the general public. But given the highly charged politics and exuberant rhetoric that have surrounded SDI from the beginning, their reaction had at least a short-lived impact. The core members of the group were Lowell Wood of the Livermore Laboratory; Gregory H. Canavan of the Los Alamos Laboratory; Angelo Codevilla,
a fellow at the Hoover Institution and formerly a member of Senator Wallop's staff; and Frederick Seitz, a former president of the National Academy of Sciences and then chairman of the official SDIO advisory committee and of the unofficial Marshall Institute study group. A few congressmen well known for their strong advocacy of the president's initiative worked closely with the group.
The counterattack on the APS study was launched at a special seminar and press conference staged by some of SDI's congressional advocates. At these events Seitz said that the report was not worthy of serious consideration: "I know of no precedent, in my long association with the American Physical Society, for the issuance of so seriously flawed a document as this." It contains "numerous errors, inconsistencies and unrealistic assumptions," he said, that are, "as far as we can tell, always in one direction—such as to make the plan for defending the American people against a Soviet nuclear attack seem more difficult than it really is." The thrust of this remark, to the effect that the APS report reflected the putative political biases of its authors, also permeated the remarks of the others who spoke at that seminar and press conference. Seitz also criticized the report for ignoring kinetic-energy weapons, despite the clear understanding on the part of the study group and the relevant government officials that this type of weapon had been omitted deliberately. Later, Seitz elaborated on his views by saying that the whole experience reminded him of the 1930s when the German scientists adjusted their scientific views to conform to the demands of the Nazi leadership. Wood added that the executive summary of the report was written "with a political goal in mind," and that he and Canavan noted that none of the six "very senior and eminent reviewers" had worked on the technological areas at issue "for at least a quarter of a century." They added that two of the six had publicly opposed the SDI before the report came out and two others had privately expressed reservations about it. Wood later changed this to "five of whom had taken public positions against SDI."
This same group also found fault with a number of technical details in the report and presented papers describing its flaws at various congressional seminars, hearings, and press conferences already cited. The APS study group considered all of the charges, conceded that the report contained some ambiguities, and issued a measured but firm reply: "On the whole, we stand by the findings of the Report, and we consider the arguments posed in these two [Wood and Canavan] papers to be without merit." The details of these charges and replies are not easily summarized
or paraphrased, but perhaps the flavor of the situation can be conveyed with the following examples.
One of the issues in controversy was the prospect for chemical laser weapons. Wood and Canavan charged that the study group had misstated the facts. In particular, they noted that the executive summary of the APS report had asserted that such lasers had been tested to date only at a power level of 200 kw, whereas in fact lasers of this type had been operated at more than a megawatt. Thus, the technology of chemical lasers did not have to be extrapolated nearly as much as the APS study had estimated in order to achieve the brightness needed for space-defense applications.
The APS group replied by first noting that its original draft had actually presented a higher value for the laser power levels already achieved experimentally, but that in its last full meeting, the group was informed by SDIO officials that for reasons of security the conclusion must read 200 kw. Even so, the statement in the report was not as misleading as it might at first appear because the higher power levels, while actually achieved, were produced in lasers whose output beams were substantially less well focused than those needed for the ultimate application, and the particular laser involved in the higher power experiments "cannot be scaled to significantly higher powers" in the range of those needed for the ultimate application.
Wood and Canavan charged that the report's conclusion that a ground-based excimer laser would require a larger source of power—1 gigawatt (1 billion w)—was inconsistent with its own calculations, which should have led to the conclusion that only 6 mw (6 million w) were needed. The study group responded by pointing out that the critics confused the calculations for impulse kill with those for thermal kill. For an impulse kill, the report estimates that a 100-megajoule laser would be required: Canavan arrives at a lower requirement by assuming a smaller diameter spot on the target, based on a much shorter engagement range and a larger mirror than the study group considered workable. For a thermal kill, where energy efficiency is much lower, the APS found that power of 1 gigawatt (gw) would be necessary—a calculation not disputed in the Canavan study. Finally, the group noted, SDIO's own actions in relegating the excimer laser to a "back up" technology indicated disagreement with Canavan's assertion that excimer lasers "could be legitimately scaled in a single step to the levels required, from present modules."
Wood and Canavan claimed that a 4 mw free-electron laser would be
adequate for purposes of strategic defense, and could operate at 40 percent efficiency. Thus, only 10 mw of delivered power would be required, rather than the 1 gw the APS calculated. The study group replied that Wood and Canavan reached their conclusion by assuming that the efficiencies achieved in an experimental "ETA accelerator" at Los Alamos could be achieved in FELs configured for the more demanding requirements of boost-phase intercept. "To our knowledge," the group reflected, "no one—including the SDIO itself and the laboratories, including Los Alamos and Livermore, building the FELs—currently predicts efficiencies for such devices that are anywhere close to those obtained on ETA."
Another issue raised by Wood and Canavan concerns the power supply needed for space-based satellites. The APS report noted that nuclear reactors would probably be required to provide "station keeping" or "housekeeping" power for satellites carrying surveillance and directed-energy kill mechanisms. Wood and Canavan contended that the study group had greatly exaggerated the need for electrical power by assuming that a continuous supply of between 100,000 and 700,000 watts would be needed for each of the one hundred satellites in the hypothesized architecture. Although that level of power could only be met by nuclear reactors, "the power needed for satellite housekeeping," according to Wood and Canavan, "is not hundreds of thousands of watts, not for any of the satellites considered in any of the 'baseline architectures' by the SDI program." The satellites under actual consideration, they claimed, would require only a few thousand watts, which are "routinely supplied" by solar photovoltaic cells and storage batteries. Higher levels of power would be needed, they pointed out, only if the satellites were to include radar units, "but the SDI has no plans for radars on any of the satellites in any of its baseline architectures."
The study group replied that the upper limits of its estimates did in fact take account of the power requirements for satellites bearing radar units, evidently on the assumption that in some proposed configurations, radar units would be mounted on at least some of the satellites. The lower limit, the study group acknowledged, was "about a factor of two higher than the estimates provided for us by SDIO officials … not an unreasonable disagreement on such a speculative engineering project." The SDIO's lower limit of 50,000 watts, the group noted, was itself considerably higher than the several thousand watts posited by Wood and Canavan.
Did the APS estimates grossly exaggerate the power needs defined by
the SDIO? Since its inception, SDIO has been cooperating with NASA and the Department of Energy in a joint project known as "SP-100" (for Space Power - 100 kw). SDIO's interest in the project reflects the finding of the Fletcher Committee that "the overall success of certain concepts is highly dependent upon the ability to generate tremendous amounts of electrical power." In its 1986 report to Congress, SDIO observed that SP-100 "is the cornerstone of the research and technology effort seeking long-term continuous power supplies." The project was needed both "to provide moderate continuous power levels for a variety of projected SDIO needs" and for other civil and military space missions.
In order to determine the official administration view of this matter, Rep. Edward Markey (D., Mass.) asked the Department of Energy to assess the objection raised by Wood and Canavan to this part of the APS report. On behalf of the department, Under Secretary Joseph F. Salgado replied that he had to "take strong exception to Dr. Wood's claims. There may be some people who have the same view as Dr. Wood, both within the external to SDIO, but the official documents provided to us and the decisions reached in concert with the Director of SDIO indicate that higher power levels are required." In a detailed commentary attached to the letter, the department noted that it "strongly disagrees with Dr. Wood's contentions regarding SDIO's 'housekeeping' power requirements," because current SDI studies indicate requirements 'from a few 10's of kWe to over 100 kWe for non-burst power duty cycles." The commentary noted that "the overall SDI architecture is still under development, and therefore the power requirements cannot be precisely defined," adding that "history would indicate that the power requirements will rise with changing mission requirements." Although some SDI staff specialists had expressed interest in lower power levels, "SP-100 technology was baselined in all of the recently sponsored SDI space power system architecture studies for providing 'housekeeping' power."
Whatever the eventual outcome with respect to power requirements for a space-based system involving directed-energy weapons, the SDIO's statements and the view expressed by the Department of Energy made it obvious that Wood and Canavan, not the APS report, grossly misstated the officially adopted parameters of the SDIO with respect to projected power levels.
These exchanges are typical of the controversy between Wood and Canavan on the one hand and the majority of informed specialists on the other. The latter are more skeptical about the prospects for strategic defense. The details of the arguments put forward by Wood and Canavan
are frequently accompanied by polemics and ad hominem remarks that serve only to confuse the nonexpert and make the argument as a whole hard to follow. Although polemics are not unknown in exchanges among partisans on such issues—and anti-SDI forces have used similar tactics—in this case the attack misfired and only weakened the optimists' position in the eyes of other technical specialists.